sir
I am sending you two technologies UTWT and GROUTED MACADAM These technologies are tested at Surat city and Thane city road
I am always of the opinion that the technology should be cheaper and accepted by people who are the stake holder These technologies do not require any special type of equipment with existing machinery we can ovelay the damaged road
The time has come to adopt these technologies in Bombay city to get road of pothole free
Roads.
I have many anxious movement during development of UTWT and GROUTED MACADAM. It was great efforts from my side to make these technology successful and used by India .
The paper published by prof B.B.Pandey of kharagpur IIT in 2008 for village road is already used in the year 2000.in BMC where Mr Naik was commissioner BMC. .I have published a paper on international conference held in Delhi. and received the trophy for novel technology
I feel we should use technology which we have developed .let us decide that city road with UTWT and village road with grouted macadam
Dr Vilas Deshmukh+91-9869026667-
Dr.Vilas Deshmukh
Monday, December 6, 2010
dear fellow citizen
DEAR FELLOW CITIZENS
Join the movement started by Dr.V.V Deshmukh
Please refer the article on road overlays published on 22nd Nov 2010 in news paper DNA The two technologies UTWT and Grouted Mecadum developed BY Dr.Deshmukh when working in research and consultancy directorate .of ACC LTD
We are using these technologies in Surat and Thane. Both the technologies used in Surat Municipal Corporation and Thane Municipal Corporation have been successful
The people as stake holder have been consulted and are happy with the performance The technology is such that you can open the traffic in seventy two hours. We the citizens are fedup with potholes and bad quality roads. Accidents are increasing rapidly.but nobody is bothered.
Why are we insensitive to this problem.?
Dr.Deshmukh has given you the technology Therefore I appeal to the Politicians and people related to the PWD ,Zilla Parishad ,NGOS , Cement and Concrete producing people. to take this matter seriously.
We all need to take this option seriously and make an appeal to the government regarding this issue for the betterment of this nation.
DR.P.BONGIRWAR
DR.DESHMUKH
I am sure we will be successful to walk on pothole free roads in our life time The safety and security of citizens is the responsibility of the citizens and the government together
we can improve the quality of concrete and there by bring about an improvement of our demanding infrastructure.
Sunday, December 5, 2010
Sunday, October 10, 2010
pothole free bombay
THE SOLUTION FOR REPAIRS OF EXISTING DAMAGED BITUMINOUS ROADS OF BOMBAY MUNICIPAL CORPORATION
Dr Deshmukh is retired material scientist from ACC LTD. He has worked on concrete especially material suitable for pothole repairs and overlays on damaged bituminous road. The author has already worked with BMC and laid this material at SION circle and N.M.JOSHI MARG It has worked well. This product we have used in SURAT city and know the city is pothole free.
The UTWT ultra thin white topping I have used this material first time in thane municipal corporation as overlay on damaged bituminous road .The successful performance of the product led to decision of using same technology for ‘TMC internal roads.
You can visit to our any of the working site to get the new technology working. you can call even the BMC engineer
DR.V.V.DESHMUKH
9869026667.
Dr Deshmukh is retired material scientist from ACC LTD. He has worked on concrete especially material suitable for pothole repairs and overlays on damaged bituminous road. The author has already worked with BMC and laid this material at SION circle and N.M.JOSHI MARG It has worked well. This product we have used in SURAT city and know the city is pothole free.
The UTWT ultra thin white topping I have used this material first time in thane municipal corporation as overlay on damaged bituminous road .The successful performance of the product led to decision of using same technology for ‘TMC internal roads.
You can visit to our any of the working site to get the new technology working. you can call even the BMC engineer
DR.V.V.DESHMUKH
9869026667.
Saturday, October 2, 2010
Sunday, August 22, 2010
Breakthrough Concrete Mix Designs For Industrial Liners And Pavement Overlays.
Breakthrough Concrete Mix Designs For Industrial Liners And Pavement Overlays.
Dr.Vilas Deshmukh
SMC Infra Structure Pvt.Ltd,Thane, India
Preamble: The Road and Society( Science and Faith)
I was the ardent student of science write from the beginning but in my thirty years of experience in scientific world I have experience that science and faith not work separately but they go hand in hand. Our purpose of doing work is to get degree and acquire position in the scientific community. Once we achieve that we forget research and do administrative work. Almost all research organizations have similar attitude, knowing and conscious of this I had joined ACC LTD in seventies at the research station in Thane.
I was working in research and development group of ACC LTD where with the cooperation of my research heads, I got the opportunity to develop new methodology and various kinds of products to lay roads which are cheaper, fast and durable. I will mention the names of people who are responsible directly or indirectly for this work. While I was busy in the development, I was introduced to various technologies from different people on different occasions, whose mention I am making in the following contributions of the scientists. Mr. Sondur then working for MBT introduced fifth generation admix carboxyl ether which has helped me to make the concrete mix workable in less, water to cement ratio. Dr A.K.Chatterjee concrete technologist ex-director ACC LTD author of many books in nineties in collaboration with Materials Research Laboratory (MRL USA ) started working on new generation cementitious material namely on chemically bonded ceramic(CBC). I had the opportunity to work with Dr Rustom Roy, Dr. Dela Roy, Prof Barry Smith from whom I have learnt the concept of packing density, which I am using in my work. And to our surprise because of the admix and improvements in material packing, I could make the concrete whose compressive strength is of the order of 1500kg/cm2 to 2000kg/cm2 the formulation of mix to achieve properties like ceramic metal became possible Then Mr. A.K.Pathak, President ACC LTD though typical production person transfer to research and consultancy directorate as if sent by some power to lead research team. He saw the commercial potential in work on CBC and because of corrosion, erosion, abrasion resistant properties used in liners in pipes and bents as liners we named it DRC-densified reinforce composite. The product has replaced conventional cast basalt used as liners. We have developed about ten products based on these applications and today the company manufactures it and supplies such cement to thermal power and chemical plants. Mr. Mittal ex-ACC employee, working with Benani cement, wanted to put slag dryer for their Benani cement plant in Dubai. We used our resistant DRC material which is it not different from conventional thinking of using the new material which has been used in market. I have completed that job with help of Pakistani people, which is an example of professionalism. We have used modified concrete of 25mm layer on damaged bituminous road. While we were working on this DRC material, Mr. A.K.Pathak president saw the commercial potential of it and we started making roads for Bombay Municipal Corporation The product called ACC MARG was launched and at many sites we successfully used this product. With our limited manpower, we undertook projects in Surat and made the city pothole-free. Further, we developed concrete with high early strength which has helped us opening the traffic on the road within merely three days. Then came Mr. K.D.Lala chief engineer Thane Municipal Corporation, unaware of the potential of ACC MRAG, in spite of the risk of failure, allowed me to experiment the product which has today become successful and the road is in service for last three years in Thane city. Then under the leadership of Mr.Suhas Mehta of SMC Infrastructure Pvt. Ltd, he has made possible alternative to concrete road. The product was placed first time in Ghantali lane, Thane city. with the initiative of the Thane municipal corporator. It was the first concrete road which was ready the next day for traffic The traffic and pedestrians started believing in the potential of the product when they used the road very next day.
Then came the another chapter, Mr. Bongirwar retired secretary of PWD and advisor to many concrete roads dams and bridges of India, pushed the product UTWT to Prime Minister Gram Sadak Yogana (PMGSY) and promised them to give the concrete road in bituminous cost. The mix is developed by author at marginally higher cost than conventional bituminous road and ready to apply village road of India
The then minister of gram sadak yojana (PMGSY) sent me to the chief engineer of this project in Maharashtra and what a surprise he took the major lead to implement this technology. Today we have received the permission to start on an experimental basis the concrete road from central government. The villagers who were deprived of roads will get opportunity to progress. The dream of common man has come to some extent near to reality.
Few common man reactions
First pedestrian:How is it possible concrete road of 100mm thickness and that to with out removing the old bituminous road ?
Second pedestrian: reflecting on a road in their locality, made their mind full with positive thoughts and responded that the road is so good even if I think of spitting on the road one, will think twice, finally not do it.
Third pedestrian: The old man was happy because of fast work He could walk next day with no trouble.
Fourth one : The people from Rabodi locality, Thane were reluctant to have the road in their area. Their negative thinking turned into positive and started appreciating the development work. Thanks to local leader of locality to convince the product to Rabodi people.
Each person whom I have mentioned above was an expert in their respective fields of working. But all has helped me to develop above mentioned product.
Is it not strange to meet all scientists at required time to go at higher step? I have given you the link of the videos of the concrete road which are cheaper and faster
• MVI_3807.AVI- http://www.youtube.com/watch?v=RFbZYfSaPl8
• mvi_4522.avi- http://www.youtube.com/watch?v=b9uyYNGF3Dg
• http://www.youtube.com/user/vilasdes#p/a/u/0/b9uyYNGF3Dg
• UTWTThane- http://www.youtube.com/watch?v=QQqFk2Zwjdc
Ten years back, the first thing I have made a mould of lord Ganesh out of my new material. And last year I have successfully laid UTWT when at that time also elephant was present at the site
Introduction :
Recent years have seen the development of many new advances in cementitious materials as ceramic like materials formed as the result of chemical reactions occurring at or near ambient temperatures. These new advances have occurred as a result of manipulating the microstructure and controlling the chemistry or both, of cements. These advances have led to the development of new families of high performance cementitious materials including very high strength materials. Some of these materials cross the boundaries of what have been defined as traditional cementitious materials, and the term chemically bonded ceramics has been used to classify these new materials. CBCs are defined at or near ambient temperatures. These new novel cements or CBCs follow the general rules of behavior of cementitious materials in certain respect. The strength of hardened paste increases as the ratio of water to cement is reduced. Because the residual porosity, its distribution and the excess uncombined molecular water are responsible for most of the limitations on the properties of conventional hardened cement paste. Many attempts have been made to reduce the amount of water used in processing. The situation has changed beginning in about 1970 as new approaches have led to the development of more advanced cement matrix composites.
1) Densification by pressure and heat
The bonds limiting the strength of cement paste are normally thought to be weak van der waals forces Before 1970,the potential strength of cement paste at theoretical density had never been approached because considerable porosity (20 to 30% or more total porosity) always remain after complete hydration of cement. Following this research resulted in achieving very high strengths by warm pressing. Compressive strengths up to 650 Mpa (compared to more typical 30 Mpa) tensile strength up to 68 Mpa and values of youngs modulus up to 40 Gpa were attained. Enormous increases in strength resulted from the removal of most of the porosity and the generation of very homogenous fine microstructure with porosity's as low as 2%.
2) Micro defect free cement.
The warm pressed cements discussed in the previous section were successful but not easy to produce in large amounts due to the high pressure used. The next step was to develop more easily processed materials. .Another innovation was the engineering of a new class of high strength materials, the MDF cement. MDF refers to the absence of relatively large voids or defects which are usually present in conventionally mixed cement paste because of entrapped air and inadequate dispersion. In the MDF process 4 to 7% of one of several water soluble polymer is added as a rheological aid to permit cement to be mixed with very small amount of water., subsequent high shear mixing produces a plastic cohesive mixture which can be shaped by extrusion or other forming technique and which sets in times ranging from minutes to hours. The highest strength materials have been prepared with calcium aluminate cement. Control of the particle size distribution for optimum particle packing was also considered important for generating strength. A final processing stage in which entrapped air is removed by applying modest pressure or heating at 80 0C resulted in a paste that is free of large defects. with excellent mechanical properties. Very low porosity's were achieved <1% as well as flexural strength of 150 Mpa. compressive strength of 300 Mpa and a young’s modulus of 50 Gpa. When MDF material is exposed to moisture, the polymer phase which MDF cement where constitute 30% on a volume basis, swells and softens. This property of MDF cement has restricted the use of its in application where water is used.
3) DSP and other densely packed systems
An important class of new materials termed DSP (Densified systems containing homogeneously arranged ultrafine particles) was first elucidated in detail by Bache The new class of materials is defined as materials with matrix comprising of 1) Densely packed particles of a size ranging from 0.5 to 100micron usually cement 2) Homogeneously arranged ultra-fine particles ranging in size from 50 A0 to 0.5 microns usually silica fume, arranged in the spaces between the larger particles. The combination of densely packed silicafume and cement was found to benefit for a combination of reasons
1) The silica particles are smaller than even the finest cement produced by grinding and therefore pack more easily into the spaces between the cement particles.
2) The silica particles are spherical in shape
3) The particles are chemically less reactive than cement, which eliminates the problem
of too rapid hardening encountered with very fine cement
4) Finally with added dispersing agents a low water requirement may be achieved.
Numerous investigations have contributed to the understanding of the effects of fine particles in densely packed cementitious materials. With 15% silica fume replacement of cement thwere are 2000000 particles of silica fume for each grain of portland cement in a concrete mixture. Concrete containing 5 to 15% silica fume have high compressive strengths up to 100 Mpa flexural strength up to 12 Mpa and young’s moduli (up to 34 Gpa)and have very low permeability to water (10-9 um).The microstructure of the critical interfacial zone between cement paste and the aggregates in concrete is more dense and uniform than when conventional pastes are used and the bond between paste and other embedded materials such as aggregates and fibers appears to be improved. The most striking results have been found with silica fume substituted pastes and DSP systems. Compressive strengths of up to 270 Mpa or higher with young’s moduli up to 80 Gpa were achieved in preparations with up to 20 to 25% silicafume at a water to solid ratio of 0.12 to 0.22 through mechanical compaction. Such materials are used to resist mechanical erosion in impeller screws for moving coal and fly ash and in flooring to industrial area. This material retains a compressive strengths of 300 Mpa up to about 500 0c and 200 Mpa at about 700 0C
Silica fume hydration reactions.
Properly dispersed silica fume particles when used in propertions to replace up to 10 % of cement significantly reduces the bleeding and segregation of the mixtures and may be used in higher proportions. Silica fume contains particles as fine as 0.1 microns or less which partially dissolve in saturated Ca(OH)2 solution in a time as early as 5 to 15 minutes, and a SiO2 rich hydrates is deposited in layers or films on the silica fume particles. Despite the early rapid reaction much silica fume is remained for later slow reaction. The fume particles play an important role in various composites when they surround each cement grain, densifying the matrix, filling the voids with the strong hydration products and improve the bonding with aggregates, and reinforcing materials such as fibers. Silica fume by reacting with alkali also affords a protection against the alkali aggregate type reaction occurring between a cement pore solution and glass fiber.
Particle packing in concrete.
The Toufar/Aim model of dry particle has been verified as adequately modeling the dry packing of mixers of powder, each with a different size distribution. Typically in the model ,materials with three different size distributions may be mixed .Furthermore, the characterization of the size distribution can be modeled by a commonly used procedure describe by Rosin-Rammler. Input to this PC-based algorithm consists of the experimentally determined tap density of each component and the characteristic diameter of the distribution as described by D in Rosin-Rammler fitting equation. The results of applying this algorithm to concrete systems have provided the mathematical basis for formulating concrete mixtures which were developed through field experience in the concrete placement. Its applications should prove useful in monitoring the quality of concrete in the design stages and to maximize performance.
Discussion and summary
The particle packing and hydration reactions in DSP cement pastes are responsible for the fine micro structural development. These complex reactions involve phase solubility, accelerating and retarding effects of a multiphase, multiparticle size distribution material, and surface effects at the solid-liquid interface. This particle packing combined with chemical reaction is extremely important for developing strength. The initial degree of dispersion of cement and fume in the paste strongly influences the development of the final hardened paste microstructure. The ultra fine particles can fill the intergranular interstices and produce a dense paste structure reflected in a high strength. Super plasticizers should be used to minimize the water demand and adequately disperse the fine particles, resulting in dense products with fine pore size, very low permeability and low ionic diffusivity. Despite the rapid early hydration, much silica fume remains unreacted until a later stage. Physical and chemical characteristics together influence the hydration kinetics. Silica fume ordinarily accelerates the early Portland cement hydration, largely because of its very high surface area, increasing the heat development and resembling high early strength cement. Fume also disperses the hydration product, provides for deposition of C- S-H and thereby fills the pore interstices with fine hydration products. The mechanical properties of some high strength DRC -type materials have been summarized in table given below
Product Name : ACCresist
Technology used : CBC/DSP
Raw materials used : 1) Cement OPC-53G /Calundum/Cal-Al-75
2) Sand
3) Calcined bauxite
4) Brown fused alumina
5) Silicon carbide
6) Fine quartz
7) Micro silica
8) Fibers
9) Plasticizer
10) Fly ash
11) Basalt
Chemical Analysis of raw materials
Basalt Slag CB Flyash Microsilica Microsilica*
SiO2 50.6 34.9 3 58.4 85.3 95.1
Al2O3 13.4 15.2 86.6 31.1 2.1 1
Fe2O3 12.4 1.6 4 5.2 3.5 0.2
CaO 10.2 35.7 1.5 0.3 0.8 0.1
MgO 6.3 6.9 0.1 0.7 3.7
LOI 1.7 1.6 0.6 1.5 3.8 1
Na2O 2.21 0.25 0.9 0.08 0.25 0.1
K2O 0.68 0.39 0.02 1.05 0.09 0.1
TiO2 2.18 0.18 4.25 1.4
SO3 0.2 0.2
Mn2O3 0.15 0.6 0.03
BFA Meta-K OPC Calundum HAC Fine quartz
SiO2 1.1 51.1 20.8 4.7 0.4 99
Al2O3 94.9 45.7 4.7 50.5 75.76 0.4
Fe2O3 1.2 0.6 3.7 4.4 0.2 0.1
CaO 0.2 0.1 63.3 32.9 23.25 0.1
MgO 0.1 0.1 0.1
LOI 0.14 1.2 1.8 1.3 0.1
Na2O 0.07 0.09 0.4
K2O 0.02 0.02 0.03
TiO2 2.47 1 0.8
SO3 2.9
Mn2O3
f-CaO 1.7 0.11
Raw material specks
OPC
IS 12269,1987
1) C3S (45-50%)
2) C3A ( 5-8%)
3) Blains Surface 3000-3500 cm2/g
4) PSD D50 25-40 microns,
90microns=3%Max
5) OPC-53 is used
CB
1) Al2O3 >85%
2) TiO2 < 7%
3) SiO2 <5%
4) CaO <2%
5) Apperent porosity 12% max
Microsilica Source Elkem-920U Low temperature application<300oc
SiO2 >85%
LOI <5%
Microsilica High temp application Source Pooja enterprise
SiO2 >90%
LOI < 2%
Fine quartz
SiO2 >90%
PSD D50 < 5-8 microns
90 microns=3%max Calundum
BS915 Part 2,1972
Compressive strength in water
1-day 300kg/cm2
3-day 400kg/cm2
Setting time 30 minutes
High alumia cement
IS 4031
Setting time 30 minutes
Compressive strength
1-Day Air curing 350 kg/cm2
at 110 0c 600kg/cm2 Brown fused alumia
Al2O3 >95%
TiO2 < 3%
CaO = 1% max
Fe2O3=1.5 % max
Fly ash
As per IS 3812,part I
Sp.Surface .>3200cm2/g
LR =40 kg/cm2
CR =80% of control
Blast furnace slag
As per IS 12089
Glass content >85%
MgO<17%
SIC
Purity =85%,Fe2O3=1%max
Purity =95%,Fe2O3=0.7%max
Plasticizers
1) Sodium salt of sulphonated napthalene formaldehyde condensate
B.D. =0.6
2) Polycarboxylic ether
Relative density =1.1
The procedure of manufacturing of DRC powder.
The above raw materials with following proportions are used to make different grades of ACCResist
Material wt%
Aggregates 30-50
Cement (OPC,HAC,SAC) 5.0-40
Quartz fine 10.0-15.0
Silica fume 5.0-10.0
Fly ash 10.0-50.0
Metakeolin 5.0-10.0
Plasticizer 0.5-3.0
Water 5.0-10.0
Preperation of ACCResist powder
1) The raw materials are weighed accurately and blended in a ball mill for 35 minutes.
2) The batch size is 1 MT
3) 5 kg representative sample is removed and sent for analysis.
4) Parameters like density,compressive strength,flexural strength are measured.
5) The finished powder with proper identification is stored in HDP bag with plastic liner
6) The powder is sent to the place where insitu application of casting is carried out.The casting
is carried out under the supervision of RCD personnel.
Mixing of powder
1) The panmixer ( 40 rpm minimumrotor speed ) of 300 litre capacity is used for mixing powder.
2) The dry powder is mixed in the above mixer for two minutes
3) 3/4 quantity of measured water (potable) is added and mixed for further five minutes.The exact
quantity of water to be added during mixing is told to the client during supply of the material.
4) The measured quantity of additive is added and the material is mixed for further five minutes.
5) The measured quantity of desired fibers is added during mixing.
6) The mix is used for insitu casting or preshaped articles.
Preparation of ACCResist
ACCResist is used as a corrosion,erosion,abrasion resistant material.There are seven grades of
ACCResist depending on the abrasion resistance reqired to be used for particular application.
The grades are as follows
E-05 : Sand as aggregate and OPC
E-10 : Calcined bauxite as aggregate and OPC
E-20 : Brown fused alumina as aggregate and OPC
E-30 : Silicon carbide as aggregate and OPC
E-10T : Calcined bauxite as aggregate and HAC
E-20T : BFA as aggregate and HAC
E-30T : SiC as aggregate and HAC
Curing of ACCResist
1) The ACCResist is cured in waterbath at 80 0c for 24 hrs.
2) ACCResist is also cured by spraying water
Properties of ACCResist
Grades E-05 E-10 E-20 E-30
Compressive strength,Mpa
BIS4032,1985
1 day 40 65 60 50-60
3 days 70 80-100 90 90
7 days 90 110 100 100-110
28 days 100 130 120 120
Flexural strength,Mpa
BIS4032,1985
1 day 9 11 9 9
3 days 12 15 13 13
7 days 13 19 18 19
28 days 15 22 20 20.0+
Hardness of aggregate,Modified 8 12-Nov 12 13
Moh's scale
Casting shrinkage %,ASTM 806-82 0.2 0.2 0.2 0.2
Particle size,mm 0.0001-4.0 0.0001-4.0 0.0001-4.0 0.0001-4.0
Density (when cast)gm/cc 2.5 2.6 2.7 2.8
Max.temp.of application(0c) 300 300 300 300
Wear resistance BS 1902 part-1A 15-20 13-15 10 6.0-9.0
Water absorption %IS 1237 0.5 0.5 0.5 0.5
Grades E-10T E-30T
Compressive strength,Mpa 140 95
Flexural strength,Mpa 17 15
Hardness of aggregate,Moh's scale 11.0-12.0 13
Casting shrinkage %,ASTM806-82 0.2 0.2
Particle size,mm 0.0001-4.0 0.0001-4.0
Density(when cast)gm/cc 2.7 2.8
Max.temp.of application (0c) 1200 1200
Wear resistance BS 1902 part-1A 10 6
Water absorption %IS 1237 0.5 0.5
The ACCResist is used for following application
1) Transportation of fine coal at Wadi
2) Slag dryer at Binani cement,Dubai
3) VRM duct at Gagal
4) Bends for fine coal transportation at Chanda
5) Fly ash slurry handling pipeline at TNEB
6) Fly ash slurry handling pipeline at ABB
7) Fly ash slurry handling pipeline at MELCO
8) Flue gas duct at chandrapur electricity board
Fast track compositions
cement 450 550 150 275
calundum 400 275
fly ash 115 15
sand 850 850 1000 1000
metal-2 400 400
metal-1 350 350 850 850
sky 2.7 2.7
pozolith 3 3
suparex 70 70
gypsum 200 130
water 200 180 120 120
strength
six hrs 10Mpa 9Mpa
comp.12hrs 11Mpa 14Mpa
comp.24hrs 24Mpa 31Mpa 23Mpa 15Mpa
Flexural
six hrs 2.8mpa 2mpa
12hrs 2.2mpa 3mpa
24hrs 3.2mpa 4mpa 3.1mpa 2.5mpa
ACCMarg: Methodology for application as flexible wearing course
Introduction
ACCMarg technology is described as a flexible composite consisting of an open-graded bitumen coated aggregates filled with a special cement grout. The joint-less surface is approximately 25 to 100 mm thick, applied to an existing asphalt or concrete pavement. The primary use of ACCMarg on road surfaces is to provide strengthening and resurfacing, for higher durability against fuel spillage, resistance to abrasion and rutting. ACCMarg has been applied to various types of pavements in India over the past few years. These include bridge decks, road junctions, roads sections etc. Based on the experience to date ACCMarg pavement can withstand abrasive action from heavy vehicles, heavy point loads, and pavement deterioration from fuel spills.
Materials and construction
The coated aggregates mixture is a porous bituminous course and is placed using standard paving techniques. Mix design procedure is used to determine the optimum binder content. The aggregate gradation is part of the ACCMarg technology. Rolling the surface with a predetermined number of passes produces a surface with 25-30 percent voids. The air voids content is critical since the grout cannot penetrate the mix if sufficient voids are not present.
After laying the porous mix, grout is introduced into the voids. The grout is composed of a proprietary material of ACC, which is wet mixed and poured into coated aggregates surface. The excess grout is squeezed over the surface and removed to improve skid resistant.
Procedure for Construction
The construction procedure is developed based on extensive research and data of field experience of ACC team.
SPECIFICATIONS
WEARING COURSE FOR PAVEMENTS
Scope of Work
The work shall consist of the general requirements for mixing and placing of coated aggregate filled with a grout. It includes the requirements for aggregate, binder, mixing at asphalt plant/ mixer, surface preparation, spreading and compacting of mix, mixing and pouring of grout
The composite shall consist entirely of aggregate coated with hot bitumen.. The voids in the finished mixture must comprise between 25 and 30 % of the total volume. The wearing course shall be laid in a thickness of 25 mm constructed of porous coated aggregates and filled with grout .
Coated Aggregate mixture: The mixture shall be as given in Table 1.
Table 1: Coated aggregate mix proportion
Material
Proportion
Bituminous material
3.8-4.0%
Aggregate
96-96.2 %
1. 1. Mix design shall conform with the requirement and the aggregates shall have a maximum size of 15 mm... After laying and rolling the Air Voids shall be in the range of 25-30%
2. Materials
2.1 Aggregate
The aggregates shall be chosen from basalt, granite, grit stone etc. The nominal size of the aggregates shall be as per requirement and in keeping with the thickness of the pavement. The aggregates shall have a maximum size of 15 mm and minimum of 5mm. The property specs is attached
Bituminous Material and Tack Coat
The bitumen shall be bitumen of 60/70 grade as per penetration test.
Modified Bitumen Emulsion as per ACC specifications. The bitumen content in emulsion is measured as per IS 8887-1995.
ACCMarg Grout:
The grout shall be made using ACCMarg dry powder.It is cement based with mineral and chemical additives. The wet mixed grout shall be made at site in a mixer. The grout property specs is attached
3. Equipment
3.1 Mixing Plant
Aggregate coating shall be produced in a Hot Mix Asphalt mixing plant/ Mixer
3.2 Mix Transportation
Mixed bitumen coated aggregates from hot mix plant shall be transported to the site in tipper trucks constructed so as to prevent loss or undue segregation of materials after loading.
3.3 Rollers
Only steel-wheel rollers of 8-10 ton, max without vibration shall be used. Use of pneumatic rollers and vibratory rollers is prohibited.
3.4 Mixing and pouring of grout
The ACCMarg grout shall be mixed in a mixer at brought to the site in wheel barrow/suitable equipments and laid.
4. Surface Preparation
The surface of the existing black top road shall be cleaned of all foreign material and broomed free of dust and all pot holes are repaired.
The tack coat of bitumen emulsion shall be applied at a rate of 0.5 kg/m2 as indicated in the specification.. The Tack Coat shall be evenly applied to the surface. The specs is attached
5. Mixing, Spreading and finishing
Mixing, spreading and finishing shall be a continuos operation. During the tack coating and the paving work only road roller necessary for the execution of the paving work shall be allowed on the coated aggregate course.
6. Installation of ACCMarg grout
No traffic on the laid porous coated aggregate should be allowed before application of the grout. The porous aggregate course shall be free of any loose particles or other contaminants.
Mixing and pouring shall be a continuous operation. Not more than 3 hour shall elapse between water addition and the time of completion of grout laying.
ACCMarg Composite
Property parameter Method of test Value
Compressive Strength(28days),Mpa on 4" core of composite IS-516 4
Abrasion resistance in mm IS-1237 4
ACCMarg Grout
% X
PC 53 G45 50
Suraksha
PSC cement
Fly ash C class
Fly ash F class 55 45
Micro silica
Pozzocrete 83
Pozzocrete 60
GGBS
Metakaolin 5
Glenium- 51
0.5 0.5
W/Cementitious ratio
0.28 0.26
compressive strength(kg/cm2)
1 day 80 200
3 days 250 450
7 days 370 500
28 days 500 620
Property parameter
Method of test Value
Density, kg/m3 IS 1528 -XII 1700-2000
Compressive strength, MPa, (3 days) IS 516
15-20
Compressive strength,MPa, (28 days) IS 516 50
Property parameter
Method of test Value
Density, kg/m3 IS 1528 -XII 1700-2000
Compressive strength, MPa, (3 days) IS 516
15-20
Compressive strength,MPa, (28 days) IS 516 50
The above does not constitute the specification of ACCMarg. Depending on the project requirement, project specific specifications are drawn.
Specification for aggregate, bitumen content for coating and the grade of bitumen are given below:
In case of aggregate, the following is the sieve analysis :
Sr.No. IS sieve designation % weight passing **
1 15-10 mm 80-100
2 10-5mm 0-20
3 0-5 mm 0-5
**The tolerance shall be +/- 5% by weight
Aggregate specification
Property parameter
Method of test Value
Flakiness and elongation index IS 2386 Max 30%
Aggregate Impact value IS 2386(Part-4) Max 30%
Los Angeles Abrasion value IS 2386(Part-4) Max 30%
Water absorption IS 2386(Part-3) Max 2%
Binder specification
Property parameter
Method of test Value
Bitumen content in emulsion IS-8887,1995 65%
Bitumen content in BM IS-8887 1995 3.8-4.0%
Bitumen Grade IS -1203-1978 60-70
This development is reported as research paper in NCCBM international seminar .The paper has received best paper award. The Copy has been attached here with. The product properties are studied by CRRI.The report is attached here with.
Trials with Metakeoline as substitute to Elkem Microsilica in GR-II
Experiments are conducted during mansoon,month of July
Cement 55 55 55 55 55 55
Flyash 40 40 42 42 43 43
Himacem 5 3 2
Microsilica 5 3 2
Glenium 0.5 0.5 0.5 0.5 0.5
Water 28 28 28 28 28 28
W/C 0.28 0.28 0.28 0.28 0.28 0.28
Slury second 30 30 30 30 30 30
Batch size(Kg) 100 100 100 100 100 100
Mixer type Concrete Concrete Concrete Concrete Concrete Concrete
Compressive strenght(kg/cm2)
1-Day 120 110 115 110 110
3-Days 430 385 400 350 300
7-Days 540 460 535 525 510
28-Days 550 510 540 544 570
Concrete with SBR Coated aggregates
% Cost Rs/kg I II III IV VII VIII
Wadi OPC - 53 G 3 9 16 10 17 17 17
Fly ash 1 9 16 10 0 8 8
Metal - I 0.25 28.4 32.25 47 25 25 24
Metal - II 0.25 28.4 0 0 25 25 25
Sand 0.5 17.8 34 33 33 24 24
Glenium - 51 160 0 0.037 0.025 0.1 0.05 0.1
Glenium stream 92 0 0.006 0.003 0 0 0
Conplast SP - 500 90 0.09 0 0 0 0 0
Microsilica 25 0 0.75 0 0 0 0
SBR - Latex 70 0 1 0 0 1 2
Water 7.2 13 12.2 6.8 6.5 4.25
Slump (mm) 5 30 30 35
Slump flow (mm) 600 600
Density(kg/m3) 2200 2300 2490 2630
Cost/100kg 67.2 184.2845 72.526 96 161.5 239.25
Compressive strength(kg/cm2)
1 day 60 70 30 147 200 282
3 day 140 95 75 249 337 446
7 day 206 130 85 357 440 597
28 day 340 215 110 479 460 703
Flexural strength(kg/cm2)
1 day
3 day 35
7 day 50 30 9 39 58 76
28 day 70 50 20 60 86 83
ACCMarg with SBR coated aggregates
Experiment
Grout II (OPC : 55, FA: 40, Microsilica : 5) was poured into it.
Slurry second: 15 sec
Compressive strength (3 day)
Grout : 141 kg/cm2
Composite : 75 kg/cm2
Trial at BANDRA KURLA COMPLEX
Experiment :
used for the trial at BANDRA KURLA COMPLEX on 10/11/04
Age kg/cm2
1day 150
1) Lavalling course (LC) THICKNESS 10MM AREA 10728 sq.metrs
Material Quantity
K-Sand 3mm 110.92 MT
Cement OPC 53 G 59.0 MT
Flyash 59.0 MT
Silicafume 7.0 MT
Suparex 1.18 MT
2) ACCFlor : Thickness 8mm area 10728 sq.metrs
Material Quantity
K-Sand -25 meah 107.5 MT
Cement white 64.5 MT
Fine quartz 32.25 MT
Silicafume 10.75 MT
Glenium 2.15 MT
Fibers 0.4mm dia *10mm length 10.75MT
Baige colour 1.61 MT
Remarks
1) We are using dahanu flyash in all our composition.Hence if there is not much difference in price of fly ash at site than the flyash from AHAMADABAD ELCTRICITY , DAHANU flyash is recommended.
2) M/S S.S.Associates is ready to set a fiber cutting unit at bridgestone site.Cutting fiber is time consuming process hence order to be placed immediately.
.
FLOOR IN BRIDGESTONE TYRE FACTORY IN PRITHUMPUR AT MADHYA PRADESH
PROPERTY COMPARISION OF ACCFlor toppings with M25 CONCRETE
PROPERTIES ACCFlor M25 Concrete REMARKS
COMPRESSIVE STRENGTH (Kg/cm2) 1000 250 More load bearing capacity
FLEXURAL STRENGHT(Kg/cm2) 150 30 More bending /stress bearing capacity
HARDNESS (Moh's) 7-8 5-6
ABRADIBILITY INDEX(Marshal Morgen Test (
10-13 25-30 Life expectancy four times for trollys and tract vehicle movement
CHLORIDE PENETRATION (coulombs),ASTM 1202,Rapid chloride penetration test 12,00,000 3000-4000 Four hundred times higher , Excellent corrosion resistance
ELECTRICAL RESISTIVITY(ohm-cm) 7,50,000 3000 250 times higher
WATER ABSORPTION(%) 0.5 10
PERMEABILITY COEFFICIENT(m/sec) 0.5*10-12
100*10-12
Salient features
1) Abrasion resistant
2) Corrosion resistant
3) Impervious to oil
4) Dust free , hygienic and easy to clean
5) Available in different colours
6) Ready to use floor in two days
7) Chemical resistant
Repair of Bridge decks of Bumbai-Pune express highway using ACCMARG Technology of ACC-LTD.
The Mumbai-Pune Express highway is the first modern expressway in the country. The ministry of surface transport during the seven five year plan identified this corridor as amongst the three most congested national highway corridors and proposed it to be developed as part of national expressway system.
The 100 kilometer long stretch that winds up the hill and literally flies over the twin hill station resorts of Lonavala and khandala 600 m up in the western ghats. It continues its impressive routes into the inland plateau towards Pune The views while travelling up the western ghats looking towards mumbai are quite spectacular. The number of civil engineering structures on this express way are
Underpass 26
Overpass 20
Major bridges/viaducts :6
Minor bridges :21
Box/slab culverts :81
Cart tracks/pedestrian crossing :33
Railway bridges :2
Interchanges :4
It is indeed a pleasure ride to reach Pune in two hours from Mumbai using the express way. Such a marvel piece of work in the history of Indian road was not with out few blemices.
The 75 mm thick reinforced concrete wearing course over bridge decks was cracking. The cracking was may be due to many reasons. There were many articles in news paper stating the reasons of cracking. The problem of cracking was more severe at bridge decks at Khandala,kune and kusgaon.These threee bridge decks of roughly 60,000 square meter were cracking and there were potholes on the decks even before one year of opening the traffic.
The MSRDC the main body responsible for building the Mumbai-Pune express highway approached ACC to give solution to this severe problem. The ACC at that time has developed ACCMARG technology which can exclusively used for resurfacing of damaged concrete and bituminous roads.The same was used to solve the problem.
ACCMARG TECHNOLOGY
ACCMARG technology can be described as a semi flexible surfacing process consisting of open graded asphalt concrete filled with a special cement grout. The joint less wearing surface is approximately 30 to 100 mm thick applied to an existing asphalt or concrete pavement. The primary use of ACCMARG on road surfaces to provide protection against fuel spillage and resistant to abrasion and rutting. ACCMARG has been applied to various types of pavements in India. These includes bridge decks, road intersections. roads sections etc. The material has been tested in and around Mumbai on several high trafficed roads. Based on the experience to date ACCMARG pavement can withstand abrasive action from heavy vehicles, heavy point loads and pavement deterioration from fuel spills.
MATERIALS AND CONSTRUCTION
The open graded bituminous macadam mixture is similar to a porous bituminous course and is placed using standard paving techniques. The mix design procedure is used to determine the optimum bitumine content. The aggregate gradation is part of the ACCMARG technology. With a bitumine content of about 4% and rolling the surface with a predetermined number of passes produces a surface with 25-30% voids. The air voids content is critical since the grout canot penetrate the mix if sufficient voids are not present.
After laying the porous bituminous mix it is allowed to cool only then is the grout introduced into the voids.The grout is composed of a proprietary material of ACC which is wet mixed and poured onto the open graded bituminous surface.The excess grout is squeezed out by brooming the surface.
PROCEDURE OF CONSTRUCTION.
The ACC’S expert team visited L&T site at Lonawalla on 25 th December 2002.The three bridge decks at Khandala, Kune and Kusgaon were damaged and around 60000 sq meter area covering all the three bridge decks were to be repaired using ACCMARG technology
The badly cracked concrete panels were removed and fresh concrete panels were laid. The rest of the panels with surface cracks and before damaging further were used as such for ACCMARG placement.
.M/S Lonawalla construction limited which is local party who has supplied the aggregates to L&T for their concrete making has been finalized for bituminous macadam placement. The general requirement of mixing and placing the open graded macadam includes requirements of aggregates, bituminous binder, hot mix asphalt plant, surface preparation, spreading and compacting of porous bitumen macadam. The asphalt mixture is of two component mixture as given in Table-1
Table-1:Asphalt mix proportion.
Material Proportion
Bituminous material 3.7-4.3%
Aggregate 95.8-96.2%
M/S Lonawalla construction has used bituminous of 60/70 grade as per penetration test from BPCL. The aggregates used were from Chakan area 30km away from Lonawalla .The aggregates used are of following specifications.
Test VALUE
Water absorption 1.6%
Aggregate impact value 24.75%
Aggregate abrasion value 29.8%
There was a challenge to ACC team to execute ACCMARG laying job in two months time without stopping the vehicular traffic. The job started from the right carriage way of Kune bridge which is 430 meters long and 11 meters wide. Out of two lanes of right carriage way one lane was kept open for traffic and the other was used for ACCMARG laying. Fourty eight hours were required for ACCMARG placement with curing period of 36hrs.
The concrete surface is cleaned and emulsified bitumen Hincol is used as tack coat and 30 mm hot bituminous macadam is placed using paver.The mixing,spreading and finishing should be a continuous operation.Not more that two hours should be elapse between porous asphalt is mixed and the time of completion of rolling.During tack coating and the paving work only traffic necessary for the execution of the paving work was allowed on asphalt base course pavement. The paved bituminous macadam is rolled with 10 ton steel wheel roller to obtained 25-30% voids. The thickness of bituminous macadam and necessary camber is monitored at regular interval.
Mixing and pouring of grout.
The M-60 grout was made using ACCMARG dry powder and water at ready mix concrete plant of L&T situated at Kusgaon few kilometers away from the site. The grout was brought to the site in transit mixers. Grout mixing, pouring and spreading was a continuous operation. Not more than three hour should elapse between water is added to the mix and the time of completion..The ACCMARG pavement is cured for further 32 hrs and open to traffic. After completion of write carriage way left carriage way was completed by similar fashion.
ACCMARG laying at Khandala which is 670 meter long and 11 meter wide amd Kusgaon which is 1090 meter long and 15 meter wide were completed. The entire job is copleted by second week of march.In case of Kune and khandala decks the ACCMARG 30mm thick is laid expansion joint to expansion joint with taper near the joints.In case of kusgaon deck the expansion joints were raised by 30 mm by welding the circular metal bar to the existing expansion joints and then 30 mm ACCMARG is laid throughout.
The job was completed in time and handed over to client L&T. This experience has proved ACCMARG as unique wearing course material for PAVEMENT OVERLAYS
REFERANCE
Ultra Thin White Topping to re-strengthen infrastructural structures and
pavements
P. Buitelaar
Contec ApS, Højbjerg, Denmark
C.R. Braam
Delft University of Technology, Delft, The Netherlands
METHODOLOGY FOR PAVEMENT APPLICATION AS WEARING COURSE
Procedure for construction: The construction procedure is development based on the field experience of ACC team.
Scope of work: The wearing course shall be laid in a thickness of 30mm constructed as 20mm thick M-15 grade concrete and 10 mm concrete modified polymer with ACC-RCD specifications. The work shall consist of the general requirements for mixing and placing concrete. It includes requirements for aggregate, binder, surface preparation ,spreading and compacting the concrete.
1) Materials
1.1) Aggregates: The aggregates shall be chosen from basalt, granite, grit stone etc.The size of the aggregates shall be as per requirement and in keeping with the thickness of the pavement for 20mm thick M-15 grade concrete layer the aggregates shall have maximum size of 12mm and minimum size of 5mm.and for 10mm top layer of cement modified polymer the aggregates shall be grit stone of size between 5mm and 1mm.The aggregates shall be tested for aggregate crush strength, aggregate impact value, moisture content and deleterious constituents as per IS-2386-1963.
1.1.1)Storage and handling of aggragates.Sufficient quantity of aggregates should be crushed in advance so that tere is adquate supply of matching aggregates available in the site.The aggregates that have become mixed with earth or foreign material shall not be used.The aggregates contaminated with fine dust are screened before use.
1.2) Cement: The cement shall be used of ordinary portland cement(OPC-43&53) ,Portland slag cement(PSC) and portland pozzolana cement (ppc).It is to be tested for physical and chemical properties as per IS-269-1967,445-1964 and 1489-1967.
1.2.1) Storage and handling of cement: Supply of cement shall be co-ordinated with its consumption so that it is not stored right through the rainy season. Cement having lumps which have been caused due to improper storage or by pressure due to over loading of bags shall not be considered for use unless these lumps can be easily powered with pressure between fingers. Before such cement is used the sample containing lumps shall be tested to fulfill minimum requirement. The cement should not be stored longer than three months.
1.3) Flyash : The flyash of any field from thermal power plant is used. The ash shall be dry and tested as per IS-3812 dated 1989.
1.4) Sand : The fine sand shall be free from soft particles,clay,shale,loam,cemented particles,mica and other foreign matter.The sand shall not contain substances more than the following
Clay lumps 4.0%
Coal and lignite 1>)%
Material passing IS sieve no 75 micron 4.0%
1.5) Microsilica:It is a biporduct of silicon industry.There are many grades of microsilica available in market.We use Elkem's 920u undensified microsilica.The party should rovide the test certificate.
1.6) SBR Latex:It is copolymer of styrene and butadine.It is anionic in nature and stabilised with nonnoninionic stabillisers.The solid content in SBR LATEX SHOULD BE 45%+1%.and the butadiene content should be 30-35%.
1.7) Plasticizer :Fourth generation polycaboxyl ethers are used.The MBT 's Glenium-51 is used
1.8) Viscosity modifier.: MBT's glenium stream -II is used as viscosity modifier.
1.9) Water : Water used shall be potable and chemically tested as per IS -456-1964.
2.0) Mixing : The concrete mixer/the mini batching plant is used for making self compacted concrete(SCC).The aggregate sand ,binder as specified in ACC COMPOSITION I &II is added in mixer .The dry material is mixed for minute and 3/4 quantity of total water is added .The mixing is continued for a minute.The Measured quantity of additive I &II are added seperately along with the remaining quantity of water.The mixing is continued for further one minute and the mix is tested for a mix property called slump flow.The mix is filled in slump cone and the mix is spread on the ground by lifting the slump cone from the ground.The diameter of the concrete spread on the ground is measured.The measured diameter should be between 600mm to 700mm.The SCC is ready for use,.
3.0) Surface preperation: The old bituminous surface on which the fresh concrete is laid shall be cleaned.The potholes if any shall be filled with bituminous macadam and rolled for compaction.Any loose material shall be removed.The clean surface shall be made wet by sprikalling water.
4) ing of 20mm SCC concrete. The concrete shall be placed on the prepared base between the form work.The concrete shall not be droped from a height greater than 90 cm and shall be deposited with in 20 minutes from thr time of discharge from the mixer.The metal angle of 30mm height is used for form work.The first 20 mm thick layer is adjusted by sliding a rod with 10mm metal sheet is welded across the lenth of the rod over the 30mm angle.
3.1) The strength of the concrete shall be ascertain from cube specimens as specified.During the progress of the work cube samples shall be casted for testing at 3,7 and 28 days.The sampling and testing shall be in accordance with IS 1199 &516 RESPECTIVELY.
4)Laying of 10mm cement modified polymer over 20 mm laid concrete.
Mixing and making concrete is similar as described earliar.The difference is specified amount of SBR lattex is added in order to coat the aggrgate.The sequence of addition is first aggregate to be added in mixer and coated with SBR Latex.After coating of aggragate with sbr latex binder,addtives and the water to be added similar way described earliar.The top 10 mm layer is added on earliar 20 mm layer after two hoursand not after six hours of placement of first layer.The horizontal rod is used for levalling and final final finish is done with roller.The strength of the concrete is measured as per IS516.
The fresh concrete shall have the slump flow between 600mm to 700mm.
5) Curing:The surface is to be kept moist for first 12 hrs.The conventional curing method of ponding is strictly avoided.The road is to be opened for traffic after 3 days.
6) Joints : Joints are cut after every 3.5 meters. The cut width of 2-5mm is fille with bitumen.In case of total 30 mm thickness 20 mm from the top is cut.
7) Properties:
8)
9) MODIFIED CONCRETE TECHNOLOGY FOR PAVEMENTS
10)
11)
12) The prime minister Gram Sadak Yogana (PMGSY) ,the government of India project to improve the connectivity in rural India.
13)
14) The scheme is getting positive response from the people The flexible pavement is recommended for cheaper in cost and fast in laying though the life of the road is short and maintenance of the road starts with in a year. More over the quality of the bitumen and its content is questionable.
15)
16) The author visit at different rural location under stood that the black topping is rejected by the people .The solution is concrete road with comparable cost with flexible solution.The PMGSY Maharashtra unit successfully found the solution by modifying the concrete technology. which is durable ,cost effective and easy to lay .The concrete which has been used in both the application relaying of damaged bituminous road and on new roads. The self compacted concrete is made by using more amount of powdery material which contain cement ,flyash and slag etc.The M40 concrete is prepared with half the quantity of cement and adding flyash which is a by product of thermal power plant.
17) The following table will give you the details of the concrete used .The study is carried in Contech group
18) Table no 1: To show the details of Mix Design of Concrete to be used as substitute to flexible pavement in PMGSY scheme
Trial No.& Trial Date Cement Flyash Micro Silica Water Sand 10 mm 20 mm Density, Kg/Cum Admixture
NS CS Qty Brand
Kg/Cum
354 22/6/09 248 269 nil 150 469 314 447 516 4.5 Glenium
356 22/6/09 266 218 nil 150 nil 591 617 632 3.4 Glenium
19)
Trial No.& Trial Date Workability, Slump, mm Compressive Strength, Mpa
0 mts 30 mts 60 mts 90 mts 120 mts 1D 3D 7D 28D 56D 90D
354 22/6/09 610 610 520 28.75 54.5 74
356 22/6/09 360 75 26 50 63
20)
21) The concrete is developed by PMGSY Maharashtra division under the supervision of Dr.V.V.Deshmukh material scientist and Mr.P.Bongirwar retired secretary of PWD.. The concrete is designed in such a way that the cost is marginally higher than the flexible road .
22) The concrete is used by TMC thane municipality for internal roads and is with out maintenance working for last three years. The photograph of the road is given below.
23)
24)
25)
26)
Dr.Vilas Deshmukh
SMC Infra Structure Pvt.Ltd,Thane, India
Preamble: The Road and Society( Science and Faith)
I was the ardent student of science write from the beginning but in my thirty years of experience in scientific world I have experience that science and faith not work separately but they go hand in hand. Our purpose of doing work is to get degree and acquire position in the scientific community. Once we achieve that we forget research and do administrative work. Almost all research organizations have similar attitude, knowing and conscious of this I had joined ACC LTD in seventies at the research station in Thane.
I was working in research and development group of ACC LTD where with the cooperation of my research heads, I got the opportunity to develop new methodology and various kinds of products to lay roads which are cheaper, fast and durable. I will mention the names of people who are responsible directly or indirectly for this work. While I was busy in the development, I was introduced to various technologies from different people on different occasions, whose mention I am making in the following contributions of the scientists. Mr. Sondur then working for MBT introduced fifth generation admix carboxyl ether which has helped me to make the concrete mix workable in less, water to cement ratio. Dr A.K.Chatterjee concrete technologist ex-director ACC LTD author of many books in nineties in collaboration with Materials Research Laboratory (MRL USA ) started working on new generation cementitious material namely on chemically bonded ceramic(CBC). I had the opportunity to work with Dr Rustom Roy, Dr. Dela Roy, Prof Barry Smith from whom I have learnt the concept of packing density, which I am using in my work. And to our surprise because of the admix and improvements in material packing, I could make the concrete whose compressive strength is of the order of 1500kg/cm2 to 2000kg/cm2 the formulation of mix to achieve properties like ceramic metal became possible Then Mr. A.K.Pathak, President ACC LTD though typical production person transfer to research and consultancy directorate as if sent by some power to lead research team. He saw the commercial potential in work on CBC and because of corrosion, erosion, abrasion resistant properties used in liners in pipes and bents as liners we named it DRC-densified reinforce composite. The product has replaced conventional cast basalt used as liners. We have developed about ten products based on these applications and today the company manufactures it and supplies such cement to thermal power and chemical plants. Mr. Mittal ex-ACC employee, working with Benani cement, wanted to put slag dryer for their Benani cement plant in Dubai. We used our resistant DRC material which is it not different from conventional thinking of using the new material which has been used in market. I have completed that job with help of Pakistani people, which is an example of professionalism. We have used modified concrete of 25mm layer on damaged bituminous road. While we were working on this DRC material, Mr. A.K.Pathak president saw the commercial potential of it and we started making roads for Bombay Municipal Corporation The product called ACC MARG was launched and at many sites we successfully used this product. With our limited manpower, we undertook projects in Surat and made the city pothole-free. Further, we developed concrete with high early strength which has helped us opening the traffic on the road within merely three days. Then came Mr. K.D.Lala chief engineer Thane Municipal Corporation, unaware of the potential of ACC MRAG, in spite of the risk of failure, allowed me to experiment the product which has today become successful and the road is in service for last three years in Thane city. Then under the leadership of Mr.Suhas Mehta of SMC Infrastructure Pvt. Ltd, he has made possible alternative to concrete road. The product was placed first time in Ghantali lane, Thane city. with the initiative of the Thane municipal corporator. It was the first concrete road which was ready the next day for traffic The traffic and pedestrians started believing in the potential of the product when they used the road very next day.
Then came the another chapter, Mr. Bongirwar retired secretary of PWD and advisor to many concrete roads dams and bridges of India, pushed the product UTWT to Prime Minister Gram Sadak Yogana (PMGSY) and promised them to give the concrete road in bituminous cost. The mix is developed by author at marginally higher cost than conventional bituminous road and ready to apply village road of India
The then minister of gram sadak yojana (PMGSY) sent me to the chief engineer of this project in Maharashtra and what a surprise he took the major lead to implement this technology. Today we have received the permission to start on an experimental basis the concrete road from central government. The villagers who were deprived of roads will get opportunity to progress. The dream of common man has come to some extent near to reality.
Few common man reactions
First pedestrian:How is it possible concrete road of 100mm thickness and that to with out removing the old bituminous road ?
Second pedestrian: reflecting on a road in their locality, made their mind full with positive thoughts and responded that the road is so good even if I think of spitting on the road one, will think twice, finally not do it.
Third pedestrian: The old man was happy because of fast work He could walk next day with no trouble.
Fourth one : The people from Rabodi locality, Thane were reluctant to have the road in their area. Their negative thinking turned into positive and started appreciating the development work. Thanks to local leader of locality to convince the product to Rabodi people.
Each person whom I have mentioned above was an expert in their respective fields of working. But all has helped me to develop above mentioned product.
Is it not strange to meet all scientists at required time to go at higher step? I have given you the link of the videos of the concrete road which are cheaper and faster
• MVI_3807.AVI- http://www.youtube.com/watch?v=RFbZYfSaPl8
• mvi_4522.avi- http://www.youtube.com/watch?v=b9uyYNGF3Dg
• http://www.youtube.com/user/vilasdes#p/a/u/0/b9uyYNGF3Dg
• UTWTThane- http://www.youtube.com/watch?v=QQqFk2Zwjdc
Ten years back, the first thing I have made a mould of lord Ganesh out of my new material. And last year I have successfully laid UTWT when at that time also elephant was present at the site
Introduction :
Recent years have seen the development of many new advances in cementitious materials as ceramic like materials formed as the result of chemical reactions occurring at or near ambient temperatures. These new advances have occurred as a result of manipulating the microstructure and controlling the chemistry or both, of cements. These advances have led to the development of new families of high performance cementitious materials including very high strength materials. Some of these materials cross the boundaries of what have been defined as traditional cementitious materials, and the term chemically bonded ceramics has been used to classify these new materials. CBCs are defined at or near ambient temperatures. These new novel cements or CBCs follow the general rules of behavior of cementitious materials in certain respect. The strength of hardened paste increases as the ratio of water to cement is reduced. Because the residual porosity, its distribution and the excess uncombined molecular water are responsible for most of the limitations on the properties of conventional hardened cement paste. Many attempts have been made to reduce the amount of water used in processing. The situation has changed beginning in about 1970 as new approaches have led to the development of more advanced cement matrix composites.
1) Densification by pressure and heat
The bonds limiting the strength of cement paste are normally thought to be weak van der waals forces Before 1970,the potential strength of cement paste at theoretical density had never been approached because considerable porosity (20 to 30% or more total porosity) always remain after complete hydration of cement. Following this research resulted in achieving very high strengths by warm pressing. Compressive strengths up to 650 Mpa (compared to more typical 30 Mpa) tensile strength up to 68 Mpa and values of youngs modulus up to 40 Gpa were attained. Enormous increases in strength resulted from the removal of most of the porosity and the generation of very homogenous fine microstructure with porosity's as low as 2%.
2) Micro defect free cement.
The warm pressed cements discussed in the previous section were successful but not easy to produce in large amounts due to the high pressure used. The next step was to develop more easily processed materials. .Another innovation was the engineering of a new class of high strength materials, the MDF cement. MDF refers to the absence of relatively large voids or defects which are usually present in conventionally mixed cement paste because of entrapped air and inadequate dispersion. In the MDF process 4 to 7% of one of several water soluble polymer is added as a rheological aid to permit cement to be mixed with very small amount of water., subsequent high shear mixing produces a plastic cohesive mixture which can be shaped by extrusion or other forming technique and which sets in times ranging from minutes to hours. The highest strength materials have been prepared with calcium aluminate cement. Control of the particle size distribution for optimum particle packing was also considered important for generating strength. A final processing stage in which entrapped air is removed by applying modest pressure or heating at 80 0C resulted in a paste that is free of large defects. with excellent mechanical properties. Very low porosity's were achieved <1% as well as flexural strength of 150 Mpa. compressive strength of 300 Mpa and a young’s modulus of 50 Gpa. When MDF material is exposed to moisture, the polymer phase which MDF cement where constitute 30% on a volume basis, swells and softens. This property of MDF cement has restricted the use of its in application where water is used.
3) DSP and other densely packed systems
An important class of new materials termed DSP (Densified systems containing homogeneously arranged ultrafine particles) was first elucidated in detail by Bache The new class of materials is defined as materials with matrix comprising of 1) Densely packed particles of a size ranging from 0.5 to 100micron usually cement 2) Homogeneously arranged ultra-fine particles ranging in size from 50 A0 to 0.5 microns usually silica fume, arranged in the spaces between the larger particles. The combination of densely packed silicafume and cement was found to benefit for a combination of reasons
1) The silica particles are smaller than even the finest cement produced by grinding and therefore pack more easily into the spaces between the cement particles.
2) The silica particles are spherical in shape
3) The particles are chemically less reactive than cement, which eliminates the problem
of too rapid hardening encountered with very fine cement
4) Finally with added dispersing agents a low water requirement may be achieved.
Numerous investigations have contributed to the understanding of the effects of fine particles in densely packed cementitious materials. With 15% silica fume replacement of cement thwere are 2000000 particles of silica fume for each grain of portland cement in a concrete mixture. Concrete containing 5 to 15% silica fume have high compressive strengths up to 100 Mpa flexural strength up to 12 Mpa and young’s moduli (up to 34 Gpa)and have very low permeability to water (10-9 um).The microstructure of the critical interfacial zone between cement paste and the aggregates in concrete is more dense and uniform than when conventional pastes are used and the bond between paste and other embedded materials such as aggregates and fibers appears to be improved. The most striking results have been found with silica fume substituted pastes and DSP systems. Compressive strengths of up to 270 Mpa or higher with young’s moduli up to 80 Gpa were achieved in preparations with up to 20 to 25% silicafume at a water to solid ratio of 0.12 to 0.22 through mechanical compaction. Such materials are used to resist mechanical erosion in impeller screws for moving coal and fly ash and in flooring to industrial area. This material retains a compressive strengths of 300 Mpa up to about 500 0c and 200 Mpa at about 700 0C
Silica fume hydration reactions.
Properly dispersed silica fume particles when used in propertions to replace up to 10 % of cement significantly reduces the bleeding and segregation of the mixtures and may be used in higher proportions. Silica fume contains particles as fine as 0.1 microns or less which partially dissolve in saturated Ca(OH)2 solution in a time as early as 5 to 15 minutes, and a SiO2 rich hydrates is deposited in layers or films on the silica fume particles. Despite the early rapid reaction much silica fume is remained for later slow reaction. The fume particles play an important role in various composites when they surround each cement grain, densifying the matrix, filling the voids with the strong hydration products and improve the bonding with aggregates, and reinforcing materials such as fibers. Silica fume by reacting with alkali also affords a protection against the alkali aggregate type reaction occurring between a cement pore solution and glass fiber.
Particle packing in concrete.
The Toufar/Aim model of dry particle has been verified as adequately modeling the dry packing of mixers of powder, each with a different size distribution. Typically in the model ,materials with three different size distributions may be mixed .Furthermore, the characterization of the size distribution can be modeled by a commonly used procedure describe by Rosin-Rammler. Input to this PC-based algorithm consists of the experimentally determined tap density of each component and the characteristic diameter of the distribution as described by D in Rosin-Rammler fitting equation. The results of applying this algorithm to concrete systems have provided the mathematical basis for formulating concrete mixtures which were developed through field experience in the concrete placement. Its applications should prove useful in monitoring the quality of concrete in the design stages and to maximize performance.
Discussion and summary
The particle packing and hydration reactions in DSP cement pastes are responsible for the fine micro structural development. These complex reactions involve phase solubility, accelerating and retarding effects of a multiphase, multiparticle size distribution material, and surface effects at the solid-liquid interface. This particle packing combined with chemical reaction is extremely important for developing strength. The initial degree of dispersion of cement and fume in the paste strongly influences the development of the final hardened paste microstructure. The ultra fine particles can fill the intergranular interstices and produce a dense paste structure reflected in a high strength. Super plasticizers should be used to minimize the water demand and adequately disperse the fine particles, resulting in dense products with fine pore size, very low permeability and low ionic diffusivity. Despite the rapid early hydration, much silica fume remains unreacted until a later stage. Physical and chemical characteristics together influence the hydration kinetics. Silica fume ordinarily accelerates the early Portland cement hydration, largely because of its very high surface area, increasing the heat development and resembling high early strength cement. Fume also disperses the hydration product, provides for deposition of C- S-H and thereby fills the pore interstices with fine hydration products. The mechanical properties of some high strength DRC -type materials have been summarized in table given below
Product Name : ACCresist
Technology used : CBC/DSP
Raw materials used : 1) Cement OPC-53G /Calundum/Cal-Al-75
2) Sand
3) Calcined bauxite
4) Brown fused alumina
5) Silicon carbide
6) Fine quartz
7) Micro silica
8) Fibers
9) Plasticizer
10) Fly ash
11) Basalt
Chemical Analysis of raw materials
Basalt Slag CB Flyash Microsilica Microsilica*
SiO2 50.6 34.9 3 58.4 85.3 95.1
Al2O3 13.4 15.2 86.6 31.1 2.1 1
Fe2O3 12.4 1.6 4 5.2 3.5 0.2
CaO 10.2 35.7 1.5 0.3 0.8 0.1
MgO 6.3 6.9 0.1 0.7 3.7
LOI 1.7 1.6 0.6 1.5 3.8 1
Na2O 2.21 0.25 0.9 0.08 0.25 0.1
K2O 0.68 0.39 0.02 1.05 0.09 0.1
TiO2 2.18 0.18 4.25 1.4
SO3 0.2 0.2
Mn2O3 0.15 0.6 0.03
BFA Meta-K OPC Calundum HAC Fine quartz
SiO2 1.1 51.1 20.8 4.7 0.4 99
Al2O3 94.9 45.7 4.7 50.5 75.76 0.4
Fe2O3 1.2 0.6 3.7 4.4 0.2 0.1
CaO 0.2 0.1 63.3 32.9 23.25 0.1
MgO 0.1 0.1 0.1
LOI 0.14 1.2 1.8 1.3 0.1
Na2O 0.07 0.09 0.4
K2O 0.02 0.02 0.03
TiO2 2.47 1 0.8
SO3 2.9
Mn2O3
f-CaO 1.7 0.11
Raw material specks
OPC
IS 12269,1987
1) C3S (45-50%)
2) C3A ( 5-8%)
3) Blains Surface 3000-3500 cm2/g
4) PSD D50 25-40 microns,
90microns=3%Max
5) OPC-53 is used
CB
1) Al2O3 >85%
2) TiO2 < 7%
3) SiO2 <5%
4) CaO <2%
5) Apperent porosity 12% max
Microsilica Source Elkem-920U Low temperature application<300oc
SiO2 >85%
LOI <5%
Microsilica High temp application Source Pooja enterprise
SiO2 >90%
LOI < 2%
Fine quartz
SiO2 >90%
PSD D50 < 5-8 microns
90 microns=3%max Calundum
BS915 Part 2,1972
Compressive strength in water
1-day 300kg/cm2
3-day 400kg/cm2
Setting time 30 minutes
High alumia cement
IS 4031
Setting time 30 minutes
Compressive strength
1-Day Air curing 350 kg/cm2
at 110 0c 600kg/cm2 Brown fused alumia
Al2O3 >95%
TiO2 < 3%
CaO = 1% max
Fe2O3=1.5 % max
Fly ash
As per IS 3812,part I
Sp.Surface .>3200cm2/g
LR =40 kg/cm2
CR =80% of control
Blast furnace slag
As per IS 12089
Glass content >85%
MgO<17%
SIC
Purity =85%,Fe2O3=1%max
Purity =95%,Fe2O3=0.7%max
Plasticizers
1) Sodium salt of sulphonated napthalene formaldehyde condensate
B.D. =0.6
2) Polycarboxylic ether
Relative density =1.1
The procedure of manufacturing of DRC powder.
The above raw materials with following proportions are used to make different grades of ACCResist
Material wt%
Aggregates 30-50
Cement (OPC,HAC,SAC) 5.0-40
Quartz fine 10.0-15.0
Silica fume 5.0-10.0
Fly ash 10.0-50.0
Metakeolin 5.0-10.0
Plasticizer 0.5-3.0
Water 5.0-10.0
Preperation of ACCResist powder
1) The raw materials are weighed accurately and blended in a ball mill for 35 minutes.
2) The batch size is 1 MT
3) 5 kg representative sample is removed and sent for analysis.
4) Parameters like density,compressive strength,flexural strength are measured.
5) The finished powder with proper identification is stored in HDP bag with plastic liner
6) The powder is sent to the place where insitu application of casting is carried out.The casting
is carried out under the supervision of RCD personnel.
Mixing of powder
1) The panmixer ( 40 rpm minimumrotor speed ) of 300 litre capacity is used for mixing powder.
2) The dry powder is mixed in the above mixer for two minutes
3) 3/4 quantity of measured water (potable) is added and mixed for further five minutes.The exact
quantity of water to be added during mixing is told to the client during supply of the material.
4) The measured quantity of additive is added and the material is mixed for further five minutes.
5) The measured quantity of desired fibers is added during mixing.
6) The mix is used for insitu casting or preshaped articles.
Preparation of ACCResist
ACCResist is used as a corrosion,erosion,abrasion resistant material.There are seven grades of
ACCResist depending on the abrasion resistance reqired to be used for particular application.
The grades are as follows
E-05 : Sand as aggregate and OPC
E-10 : Calcined bauxite as aggregate and OPC
E-20 : Brown fused alumina as aggregate and OPC
E-30 : Silicon carbide as aggregate and OPC
E-10T : Calcined bauxite as aggregate and HAC
E-20T : BFA as aggregate and HAC
E-30T : SiC as aggregate and HAC
Curing of ACCResist
1) The ACCResist is cured in waterbath at 80 0c for 24 hrs.
2) ACCResist is also cured by spraying water
Properties of ACCResist
Grades E-05 E-10 E-20 E-30
Compressive strength,Mpa
BIS4032,1985
1 day 40 65 60 50-60
3 days 70 80-100 90 90
7 days 90 110 100 100-110
28 days 100 130 120 120
Flexural strength,Mpa
BIS4032,1985
1 day 9 11 9 9
3 days 12 15 13 13
7 days 13 19 18 19
28 days 15 22 20 20.0+
Hardness of aggregate,Modified 8 12-Nov 12 13
Moh's scale
Casting shrinkage %,ASTM 806-82 0.2 0.2 0.2 0.2
Particle size,mm 0.0001-4.0 0.0001-4.0 0.0001-4.0 0.0001-4.0
Density (when cast)gm/cc 2.5 2.6 2.7 2.8
Max.temp.of application(0c) 300 300 300 300
Wear resistance BS 1902 part-1A 15-20 13-15 10 6.0-9.0
Water absorption %IS 1237 0.5 0.5 0.5 0.5
Grades E-10T E-30T
Compressive strength,Mpa 140 95
Flexural strength,Mpa 17 15
Hardness of aggregate,Moh's scale 11.0-12.0 13
Casting shrinkage %,ASTM806-82 0.2 0.2
Particle size,mm 0.0001-4.0 0.0001-4.0
Density(when cast)gm/cc 2.7 2.8
Max.temp.of application (0c) 1200 1200
Wear resistance BS 1902 part-1A 10 6
Water absorption %IS 1237 0.5 0.5
The ACCResist is used for following application
1) Transportation of fine coal at Wadi
2) Slag dryer at Binani cement,Dubai
3) VRM duct at Gagal
4) Bends for fine coal transportation at Chanda
5) Fly ash slurry handling pipeline at TNEB
6) Fly ash slurry handling pipeline at ABB
7) Fly ash slurry handling pipeline at MELCO
8) Flue gas duct at chandrapur electricity board
Fast track compositions
cement 450 550 150 275
calundum 400 275
fly ash 115 15
sand 850 850 1000 1000
metal-2 400 400
metal-1 350 350 850 850
sky 2.7 2.7
pozolith 3 3
suparex 70 70
gypsum 200 130
water 200 180 120 120
strength
six hrs 10Mpa 9Mpa
comp.12hrs 11Mpa 14Mpa
comp.24hrs 24Mpa 31Mpa 23Mpa 15Mpa
Flexural
six hrs 2.8mpa 2mpa
12hrs 2.2mpa 3mpa
24hrs 3.2mpa 4mpa 3.1mpa 2.5mpa
ACCMarg: Methodology for application as flexible wearing course
Introduction
ACCMarg technology is described as a flexible composite consisting of an open-graded bitumen coated aggregates filled with a special cement grout. The joint-less surface is approximately 25 to 100 mm thick, applied to an existing asphalt or concrete pavement. The primary use of ACCMarg on road surfaces is to provide strengthening and resurfacing, for higher durability against fuel spillage, resistance to abrasion and rutting. ACCMarg has been applied to various types of pavements in India over the past few years. These include bridge decks, road junctions, roads sections etc. Based on the experience to date ACCMarg pavement can withstand abrasive action from heavy vehicles, heavy point loads, and pavement deterioration from fuel spills.
Materials and construction
The coated aggregates mixture is a porous bituminous course and is placed using standard paving techniques. Mix design procedure is used to determine the optimum binder content. The aggregate gradation is part of the ACCMarg technology. Rolling the surface with a predetermined number of passes produces a surface with 25-30 percent voids. The air voids content is critical since the grout cannot penetrate the mix if sufficient voids are not present.
After laying the porous mix, grout is introduced into the voids. The grout is composed of a proprietary material of ACC, which is wet mixed and poured into coated aggregates surface. The excess grout is squeezed over the surface and removed to improve skid resistant.
Procedure for Construction
The construction procedure is developed based on extensive research and data of field experience of ACC team.
SPECIFICATIONS
WEARING COURSE FOR PAVEMENTS
Scope of Work
The work shall consist of the general requirements for mixing and placing of coated aggregate filled with a grout. It includes the requirements for aggregate, binder, mixing at asphalt plant/ mixer, surface preparation, spreading and compacting of mix, mixing and pouring of grout
The composite shall consist entirely of aggregate coated with hot bitumen.. The voids in the finished mixture must comprise between 25 and 30 % of the total volume. The wearing course shall be laid in a thickness of 25 mm constructed of porous coated aggregates and filled with grout .
Coated Aggregate mixture: The mixture shall be as given in Table 1.
Table 1: Coated aggregate mix proportion
Material
Proportion
Bituminous material
3.8-4.0%
Aggregate
96-96.2 %
1. 1. Mix design shall conform with the requirement and the aggregates shall have a maximum size of 15 mm... After laying and rolling the Air Voids shall be in the range of 25-30%
2. Materials
2.1 Aggregate
The aggregates shall be chosen from basalt, granite, grit stone etc. The nominal size of the aggregates shall be as per requirement and in keeping with the thickness of the pavement. The aggregates shall have a maximum size of 15 mm and minimum of 5mm. The property specs is attached
Bituminous Material and Tack Coat
The bitumen shall be bitumen of 60/70 grade as per penetration test.
Modified Bitumen Emulsion as per ACC specifications. The bitumen content in emulsion is measured as per IS 8887-1995.
ACCMarg Grout:
The grout shall be made using ACCMarg dry powder.It is cement based with mineral and chemical additives. The wet mixed grout shall be made at site in a mixer. The grout property specs is attached
3. Equipment
3.1 Mixing Plant
Aggregate coating shall be produced in a Hot Mix Asphalt mixing plant/ Mixer
3.2 Mix Transportation
Mixed bitumen coated aggregates from hot mix plant shall be transported to the site in tipper trucks constructed so as to prevent loss or undue segregation of materials after loading.
3.3 Rollers
Only steel-wheel rollers of 8-10 ton, max without vibration shall be used. Use of pneumatic rollers and vibratory rollers is prohibited.
3.4 Mixing and pouring of grout
The ACCMarg grout shall be mixed in a mixer at brought to the site in wheel barrow/suitable equipments and laid.
4. Surface Preparation
The surface of the existing black top road shall be cleaned of all foreign material and broomed free of dust and all pot holes are repaired.
The tack coat of bitumen emulsion shall be applied at a rate of 0.5 kg/m2 as indicated in the specification.. The Tack Coat shall be evenly applied to the surface. The specs is attached
5. Mixing, Spreading and finishing
Mixing, spreading and finishing shall be a continuos operation. During the tack coating and the paving work only road roller necessary for the execution of the paving work shall be allowed on the coated aggregate course.
6. Installation of ACCMarg grout
No traffic on the laid porous coated aggregate should be allowed before application of the grout. The porous aggregate course shall be free of any loose particles or other contaminants.
Mixing and pouring shall be a continuous operation. Not more than 3 hour shall elapse between water addition and the time of completion of grout laying.
ACCMarg Composite
Property parameter Method of test Value
Compressive Strength(28days),Mpa on 4" core of composite IS-516 4
Abrasion resistance in mm IS-1237 4
ACCMarg Grout
% X
PC 53 G45 50
Suraksha
PSC cement
Fly ash C class
Fly ash F class 55 45
Micro silica
Pozzocrete 83
Pozzocrete 60
GGBS
Metakaolin 5
Glenium- 51
0.5 0.5
W/Cementitious ratio
0.28 0.26
compressive strength(kg/cm2)
1 day 80 200
3 days 250 450
7 days 370 500
28 days 500 620
Property parameter
Method of test Value
Density, kg/m3 IS 1528 -XII 1700-2000
Compressive strength, MPa, (3 days) IS 516
15-20
Compressive strength,MPa, (28 days) IS 516 50
Property parameter
Method of test Value
Density, kg/m3 IS 1528 -XII 1700-2000
Compressive strength, MPa, (3 days) IS 516
15-20
Compressive strength,MPa, (28 days) IS 516 50
The above does not constitute the specification of ACCMarg. Depending on the project requirement, project specific specifications are drawn.
Specification for aggregate, bitumen content for coating and the grade of bitumen are given below:
In case of aggregate, the following is the sieve analysis :
Sr.No. IS sieve designation % weight passing **
1 15-10 mm 80-100
2 10-5mm 0-20
3 0-5 mm 0-5
**The tolerance shall be +/- 5% by weight
Aggregate specification
Property parameter
Method of test Value
Flakiness and elongation index IS 2386 Max 30%
Aggregate Impact value IS 2386(Part-4) Max 30%
Los Angeles Abrasion value IS 2386(Part-4) Max 30%
Water absorption IS 2386(Part-3) Max 2%
Binder specification
Property parameter
Method of test Value
Bitumen content in emulsion IS-8887,1995 65%
Bitumen content in BM IS-8887 1995 3.8-4.0%
Bitumen Grade IS -1203-1978 60-70
This development is reported as research paper in NCCBM international seminar .The paper has received best paper award. The Copy has been attached here with. The product properties are studied by CRRI.The report is attached here with.
Trials with Metakeoline as substitute to Elkem Microsilica in GR-II
Experiments are conducted during mansoon,month of July
Cement 55 55 55 55 55 55
Flyash 40 40 42 42 43 43
Himacem 5 3 2
Microsilica 5 3 2
Glenium 0.5 0.5 0.5 0.5 0.5
Water 28 28 28 28 28 28
W/C 0.28 0.28 0.28 0.28 0.28 0.28
Slury second 30 30 30 30 30 30
Batch size(Kg) 100 100 100 100 100 100
Mixer type Concrete Concrete Concrete Concrete Concrete Concrete
Compressive strenght(kg/cm2)
1-Day 120 110 115 110 110
3-Days 430 385 400 350 300
7-Days 540 460 535 525 510
28-Days 550 510 540 544 570
Concrete with SBR Coated aggregates
% Cost Rs/kg I II III IV VII VIII
Wadi OPC - 53 G 3 9 16 10 17 17 17
Fly ash 1 9 16 10 0 8 8
Metal - I 0.25 28.4 32.25 47 25 25 24
Metal - II 0.25 28.4 0 0 25 25 25
Sand 0.5 17.8 34 33 33 24 24
Glenium - 51 160 0 0.037 0.025 0.1 0.05 0.1
Glenium stream 92 0 0.006 0.003 0 0 0
Conplast SP - 500 90 0.09 0 0 0 0 0
Microsilica 25 0 0.75 0 0 0 0
SBR - Latex 70 0 1 0 0 1 2
Water 7.2 13 12.2 6.8 6.5 4.25
Slump (mm) 5 30 30 35
Slump flow (mm) 600 600
Density(kg/m3) 2200 2300 2490 2630
Cost/100kg 67.2 184.2845 72.526 96 161.5 239.25
Compressive strength(kg/cm2)
1 day 60 70 30 147 200 282
3 day 140 95 75 249 337 446
7 day 206 130 85 357 440 597
28 day 340 215 110 479 460 703
Flexural strength(kg/cm2)
1 day
3 day 35
7 day 50 30 9 39 58 76
28 day 70 50 20 60 86 83
ACCMarg with SBR coated aggregates
Experiment
Grout II (OPC : 55, FA: 40, Microsilica : 5) was poured into it.
Slurry second: 15 sec
Compressive strength (3 day)
Grout : 141 kg/cm2
Composite : 75 kg/cm2
Trial at BANDRA KURLA COMPLEX
Experiment :
used for the trial at BANDRA KURLA COMPLEX on 10/11/04
Age kg/cm2
1day 150
1) Lavalling course (LC) THICKNESS 10MM AREA 10728 sq.metrs
Material Quantity
K-Sand 3mm 110.92 MT
Cement OPC 53 G 59.0 MT
Flyash 59.0 MT
Silicafume 7.0 MT
Suparex 1.18 MT
2) ACCFlor : Thickness 8mm area 10728 sq.metrs
Material Quantity
K-Sand -25 meah 107.5 MT
Cement white 64.5 MT
Fine quartz 32.25 MT
Silicafume 10.75 MT
Glenium 2.15 MT
Fibers 0.4mm dia *10mm length 10.75MT
Baige colour 1.61 MT
Remarks
1) We are using dahanu flyash in all our composition.Hence if there is not much difference in price of fly ash at site than the flyash from AHAMADABAD ELCTRICITY , DAHANU flyash is recommended.
2) M/S S.S.Associates is ready to set a fiber cutting unit at bridgestone site.Cutting fiber is time consuming process hence order to be placed immediately.
.
FLOOR IN BRIDGESTONE TYRE FACTORY IN PRITHUMPUR AT MADHYA PRADESH
PROPERTY COMPARISION OF ACCFlor toppings with M25 CONCRETE
PROPERTIES ACCFlor M25 Concrete REMARKS
COMPRESSIVE STRENGTH (Kg/cm2) 1000 250 More load bearing capacity
FLEXURAL STRENGHT(Kg/cm2) 150 30 More bending /stress bearing capacity
HARDNESS (Moh's) 7-8 5-6
ABRADIBILITY INDEX(Marshal Morgen Test (
10-13 25-30 Life expectancy four times for trollys and tract vehicle movement
CHLORIDE PENETRATION (coulombs),ASTM 1202,Rapid chloride penetration test 12,00,000 3000-4000 Four hundred times higher , Excellent corrosion resistance
ELECTRICAL RESISTIVITY(ohm-cm) 7,50,000 3000 250 times higher
WATER ABSORPTION(%) 0.5 10
PERMEABILITY COEFFICIENT(m/sec) 0.5*10-12
100*10-12
Salient features
1) Abrasion resistant
2) Corrosion resistant
3) Impervious to oil
4) Dust free , hygienic and easy to clean
5) Available in different colours
6) Ready to use floor in two days
7) Chemical resistant
Repair of Bridge decks of Bumbai-Pune express highway using ACCMARG Technology of ACC-LTD.
The Mumbai-Pune Express highway is the first modern expressway in the country. The ministry of surface transport during the seven five year plan identified this corridor as amongst the three most congested national highway corridors and proposed it to be developed as part of national expressway system.
The 100 kilometer long stretch that winds up the hill and literally flies over the twin hill station resorts of Lonavala and khandala 600 m up in the western ghats. It continues its impressive routes into the inland plateau towards Pune The views while travelling up the western ghats looking towards mumbai are quite spectacular. The number of civil engineering structures on this express way are
Underpass 26
Overpass 20
Major bridges/viaducts :6
Minor bridges :21
Box/slab culverts :81
Cart tracks/pedestrian crossing :33
Railway bridges :2
Interchanges :4
It is indeed a pleasure ride to reach Pune in two hours from Mumbai using the express way. Such a marvel piece of work in the history of Indian road was not with out few blemices.
The 75 mm thick reinforced concrete wearing course over bridge decks was cracking. The cracking was may be due to many reasons. There were many articles in news paper stating the reasons of cracking. The problem of cracking was more severe at bridge decks at Khandala,kune and kusgaon.These threee bridge decks of roughly 60,000 square meter were cracking and there were potholes on the decks even before one year of opening the traffic.
The MSRDC the main body responsible for building the Mumbai-Pune express highway approached ACC to give solution to this severe problem. The ACC at that time has developed ACCMARG technology which can exclusively used for resurfacing of damaged concrete and bituminous roads.The same was used to solve the problem.
ACCMARG TECHNOLOGY
ACCMARG technology can be described as a semi flexible surfacing process consisting of open graded asphalt concrete filled with a special cement grout. The joint less wearing surface is approximately 30 to 100 mm thick applied to an existing asphalt or concrete pavement. The primary use of ACCMARG on road surfaces to provide protection against fuel spillage and resistant to abrasion and rutting. ACCMARG has been applied to various types of pavements in India. These includes bridge decks, road intersections. roads sections etc. The material has been tested in and around Mumbai on several high trafficed roads. Based on the experience to date ACCMARG pavement can withstand abrasive action from heavy vehicles, heavy point loads and pavement deterioration from fuel spills.
MATERIALS AND CONSTRUCTION
The open graded bituminous macadam mixture is similar to a porous bituminous course and is placed using standard paving techniques. The mix design procedure is used to determine the optimum bitumine content. The aggregate gradation is part of the ACCMARG technology. With a bitumine content of about 4% and rolling the surface with a predetermined number of passes produces a surface with 25-30% voids. The air voids content is critical since the grout canot penetrate the mix if sufficient voids are not present.
After laying the porous bituminous mix it is allowed to cool only then is the grout introduced into the voids.The grout is composed of a proprietary material of ACC which is wet mixed and poured onto the open graded bituminous surface.The excess grout is squeezed out by brooming the surface.
PROCEDURE OF CONSTRUCTION.
The ACC’S expert team visited L&T site at Lonawalla on 25 th December 2002.The three bridge decks at Khandala, Kune and Kusgaon were damaged and around 60000 sq meter area covering all the three bridge decks were to be repaired using ACCMARG technology
The badly cracked concrete panels were removed and fresh concrete panels were laid. The rest of the panels with surface cracks and before damaging further were used as such for ACCMARG placement.
.M/S Lonawalla construction limited which is local party who has supplied the aggregates to L&T for their concrete making has been finalized for bituminous macadam placement. The general requirement of mixing and placing the open graded macadam includes requirements of aggregates, bituminous binder, hot mix asphalt plant, surface preparation, spreading and compacting of porous bitumen macadam. The asphalt mixture is of two component mixture as given in Table-1
Table-1:Asphalt mix proportion.
Material Proportion
Bituminous material 3.7-4.3%
Aggregate 95.8-96.2%
M/S Lonawalla construction has used bituminous of 60/70 grade as per penetration test from BPCL. The aggregates used were from Chakan area 30km away from Lonawalla .The aggregates used are of following specifications.
Test VALUE
Water absorption 1.6%
Aggregate impact value 24.75%
Aggregate abrasion value 29.8%
There was a challenge to ACC team to execute ACCMARG laying job in two months time without stopping the vehicular traffic. The job started from the right carriage way of Kune bridge which is 430 meters long and 11 meters wide. Out of two lanes of right carriage way one lane was kept open for traffic and the other was used for ACCMARG laying. Fourty eight hours were required for ACCMARG placement with curing period of 36hrs.
The concrete surface is cleaned and emulsified bitumen Hincol is used as tack coat and 30 mm hot bituminous macadam is placed using paver.The mixing,spreading and finishing should be a continuous operation.Not more that two hours should be elapse between porous asphalt is mixed and the time of completion of rolling.During tack coating and the paving work only traffic necessary for the execution of the paving work was allowed on asphalt base course pavement. The paved bituminous macadam is rolled with 10 ton steel wheel roller to obtained 25-30% voids. The thickness of bituminous macadam and necessary camber is monitored at regular interval.
Mixing and pouring of grout.
The M-60 grout was made using ACCMARG dry powder and water at ready mix concrete plant of L&T situated at Kusgaon few kilometers away from the site. The grout was brought to the site in transit mixers. Grout mixing, pouring and spreading was a continuous operation. Not more than three hour should elapse between water is added to the mix and the time of completion..The ACCMARG pavement is cured for further 32 hrs and open to traffic. After completion of write carriage way left carriage way was completed by similar fashion.
ACCMARG laying at Khandala which is 670 meter long and 11 meter wide amd Kusgaon which is 1090 meter long and 15 meter wide were completed. The entire job is copleted by second week of march.In case of Kune and khandala decks the ACCMARG 30mm thick is laid expansion joint to expansion joint with taper near the joints.In case of kusgaon deck the expansion joints were raised by 30 mm by welding the circular metal bar to the existing expansion joints and then 30 mm ACCMARG is laid throughout.
The job was completed in time and handed over to client L&T. This experience has proved ACCMARG as unique wearing course material for PAVEMENT OVERLAYS
REFERANCE
Ultra Thin White Topping to re-strengthen infrastructural structures and
pavements
P. Buitelaar
Contec ApS, Højbjerg, Denmark
C.R. Braam
Delft University of Technology, Delft, The Netherlands
METHODOLOGY FOR PAVEMENT APPLICATION AS WEARING COURSE
Procedure for construction: The construction procedure is development based on the field experience of ACC team.
Scope of work: The wearing course shall be laid in a thickness of 30mm constructed as 20mm thick M-15 grade concrete and 10 mm concrete modified polymer with ACC-RCD specifications. The work shall consist of the general requirements for mixing and placing concrete. It includes requirements for aggregate, binder, surface preparation ,spreading and compacting the concrete.
1) Materials
1.1) Aggregates: The aggregates shall be chosen from basalt, granite, grit stone etc.The size of the aggregates shall be as per requirement and in keeping with the thickness of the pavement for 20mm thick M-15 grade concrete layer the aggregates shall have maximum size of 12mm and minimum size of 5mm.and for 10mm top layer of cement modified polymer the aggregates shall be grit stone of size between 5mm and 1mm.The aggregates shall be tested for aggregate crush strength, aggregate impact value, moisture content and deleterious constituents as per IS-2386-1963.
1.1.1)Storage and handling of aggragates.Sufficient quantity of aggregates should be crushed in advance so that tere is adquate supply of matching aggregates available in the site.The aggregates that have become mixed with earth or foreign material shall not be used.The aggregates contaminated with fine dust are screened before use.
1.2) Cement: The cement shall be used of ordinary portland cement(OPC-43&53) ,Portland slag cement(PSC) and portland pozzolana cement (ppc).It is to be tested for physical and chemical properties as per IS-269-1967,445-1964 and 1489-1967.
1.2.1) Storage and handling of cement: Supply of cement shall be co-ordinated with its consumption so that it is not stored right through the rainy season. Cement having lumps which have been caused due to improper storage or by pressure due to over loading of bags shall not be considered for use unless these lumps can be easily powered with pressure between fingers. Before such cement is used the sample containing lumps shall be tested to fulfill minimum requirement. The cement should not be stored longer than three months.
1.3) Flyash : The flyash of any field from thermal power plant is used. The ash shall be dry and tested as per IS-3812 dated 1989.
1.4) Sand : The fine sand shall be free from soft particles,clay,shale,loam,cemented particles,mica and other foreign matter.The sand shall not contain substances more than the following
Clay lumps 4.0%
Coal and lignite 1>)%
Material passing IS sieve no 75 micron 4.0%
1.5) Microsilica:It is a biporduct of silicon industry.There are many grades of microsilica available in market.We use Elkem's 920u undensified microsilica.The party should rovide the test certificate.
1.6) SBR Latex:It is copolymer of styrene and butadine.It is anionic in nature and stabilised with nonnoninionic stabillisers.The solid content in SBR LATEX SHOULD BE 45%+1%.and the butadiene content should be 30-35%.
1.7) Plasticizer :Fourth generation polycaboxyl ethers are used.The MBT 's Glenium-51 is used
1.8) Viscosity modifier.: MBT's glenium stream -II is used as viscosity modifier.
1.9) Water : Water used shall be potable and chemically tested as per IS -456-1964.
2.0) Mixing : The concrete mixer/the mini batching plant is used for making self compacted concrete(SCC).The aggregate sand ,binder as specified in ACC COMPOSITION I &II is added in mixer .The dry material is mixed for minute and 3/4 quantity of total water is added .The mixing is continued for a minute.The Measured quantity of additive I &II are added seperately along with the remaining quantity of water.The mixing is continued for further one minute and the mix is tested for a mix property called slump flow.The mix is filled in slump cone and the mix is spread on the ground by lifting the slump cone from the ground.The diameter of the concrete spread on the ground is measured.The measured diameter should be between 600mm to 700mm.The SCC is ready for use,.
3.0) Surface preperation: The old bituminous surface on which the fresh concrete is laid shall be cleaned.The potholes if any shall be filled with bituminous macadam and rolled for compaction.Any loose material shall be removed.The clean surface shall be made wet by sprikalling water.
4) ing of 20mm SCC concrete. The concrete shall be placed on the prepared base between the form work.The concrete shall not be droped from a height greater than 90 cm and shall be deposited with in 20 minutes from thr time of discharge from the mixer.The metal angle of 30mm height is used for form work.The first 20 mm thick layer is adjusted by sliding a rod with 10mm metal sheet is welded across the lenth of the rod over the 30mm angle.
3.1) The strength of the concrete shall be ascertain from cube specimens as specified.During the progress of the work cube samples shall be casted for testing at 3,7 and 28 days.The sampling and testing shall be in accordance with IS 1199 &516 RESPECTIVELY.
4)Laying of 10mm cement modified polymer over 20 mm laid concrete.
Mixing and making concrete is similar as described earliar.The difference is specified amount of SBR lattex is added in order to coat the aggrgate.The sequence of addition is first aggregate to be added in mixer and coated with SBR Latex.After coating of aggragate with sbr latex binder,addtives and the water to be added similar way described earliar.The top 10 mm layer is added on earliar 20 mm layer after two hoursand not after six hours of placement of first layer.The horizontal rod is used for levalling and final final finish is done with roller.The strength of the concrete is measured as per IS516.
The fresh concrete shall have the slump flow between 600mm to 700mm.
5) Curing:The surface is to be kept moist for first 12 hrs.The conventional curing method of ponding is strictly avoided.The road is to be opened for traffic after 3 days.
6) Joints : Joints are cut after every 3.5 meters. The cut width of 2-5mm is fille with bitumen.In case of total 30 mm thickness 20 mm from the top is cut.
7) Properties:
8)
9) MODIFIED CONCRETE TECHNOLOGY FOR PAVEMENTS
10)
11)
12) The prime minister Gram Sadak Yogana (PMGSY) ,the government of India project to improve the connectivity in rural India.
13)
14) The scheme is getting positive response from the people The flexible pavement is recommended for cheaper in cost and fast in laying though the life of the road is short and maintenance of the road starts with in a year. More over the quality of the bitumen and its content is questionable.
15)
16) The author visit at different rural location under stood that the black topping is rejected by the people .The solution is concrete road with comparable cost with flexible solution.The PMGSY Maharashtra unit successfully found the solution by modifying the concrete technology. which is durable ,cost effective and easy to lay .The concrete which has been used in both the application relaying of damaged bituminous road and on new roads. The self compacted concrete is made by using more amount of powdery material which contain cement ,flyash and slag etc.The M40 concrete is prepared with half the quantity of cement and adding flyash which is a by product of thermal power plant.
17) The following table will give you the details of the concrete used .The study is carried in Contech group
18) Table no 1: To show the details of Mix Design of Concrete to be used as substitute to flexible pavement in PMGSY scheme
Trial No.& Trial Date Cement Flyash Micro Silica Water Sand 10 mm 20 mm Density, Kg/Cum Admixture
NS CS Qty Brand
Kg/Cum
354 22/6/09 248 269 nil 150 469 314 447 516 4.5 Glenium
356 22/6/09 266 218 nil 150 nil 591 617 632 3.4 Glenium
19)
Trial No.& Trial Date Workability, Slump, mm Compressive Strength, Mpa
0 mts 30 mts 60 mts 90 mts 120 mts 1D 3D 7D 28D 56D 90D
354 22/6/09 610 610 520 28.75 54.5 74
356 22/6/09 360 75 26 50 63
20)
21) The concrete is developed by PMGSY Maharashtra division under the supervision of Dr.V.V.Deshmukh material scientist and Mr.P.Bongirwar retired secretary of PWD.. The concrete is designed in such a way that the cost is marginally higher than the flexible road .
22) The concrete is used by TMC thane municipality for internal roads and is with out maintenance working for last three years. The photograph of the road is given below.
23)
24)
25)
26)
Wednesday, July 28, 2010
mr zagade commissionar pune
From 26th October 2009
Dr.V.V.Deshmukh
Managing Director
Surface Solutions Pvt.Ltd
Concrete technologies
Email vilasdes@gmail.com
Mobile 9869026667
To
Mr.Mahesh Zagade
The Commissioner
Pune Municipal Corporation
Sivaji Nagar
Pune 411005
Sub : UTWT at Bhosari colony in Pune city
Sir
The ULTRA THIN WHITE TOPPING (UTWT) which Pune Municipality is using for over lay to improve the damaged bituminous road is learnt by PMC Engineer along with contractor and consultant who visited our site in Thane which is developed by Dr.V.V.Deshmukh in consultation with Mr.P.Bongirwar. The same team have shown the successful demonstration to PMC engineer in Pune city.
Observing the performance of our work the Thane Municipality Corporation has sanctioned the budget of Rs 20 crores for UTWT to be used in city internal roads.
The present practice of that UTWT, which Pune Municipality Corporation is using, is not the correct technique and thereby not getting the expected benefits and this technique is optimised by us and proven from our experimental patch at Dahanukar Colony, Pune.
.
The following are the aspects that correct UTWT technology would help is
Cement use: one bag less per cubic meter which helps in reducing the carbon dioxide in the atmosphere and also the cost of surfacing. The idea of not using additive like fly ash, slag as substitute to cement is an old technique where as to achieve high strength we have to use this additive.
Use of fly ash: the fly ash, which is a by product of thermal power plant ,whose production of 100million tonnes per year and has problem of dumping., helps to be used as substitute to cement.
Process: the self compacted technique used by us in laying is faster and thus reducing times for unloading and completing the work faster. Use of machine
like vibrators for compaction is not required because of self compacting technique which is used by us. The mix which PMC is using is very harsh and takes two hours to unload where as our mix is semi self compacting and unloaded in half an hour.
The use of poly propylene strips helps to avoid cutting (1m X 1 m) , which results in less noise pollution and reduction of cost of Rs 100 per running meter.
The traffic can be opened in 72 hrs vs. 7 days, which reduces the inconvenience to pedestrians; less trouble to traffic diversion and traffic load to certain areas are avoided.
The above mentioned points are highlighted in light of correct UTWT technology which is today standardised by us
I also wish to highlight the following additional advantages of this UTWT technology.
Improved performance: The life of road is increased due use of UTWT than the bituminous road which saves maintenance cost and there is no rutting or wash boarding
In the recycle cost study it proves to be cheaper in the cycle of maintenance due to its longevity.
The light colour of the road increases illumino effect due to increased reflectivity and thereby reducing the heat content of the environment.
The less consumption of raw materials has direct bearing on the unit cost of the road surface laying.
Minimizes waste. Less material to landfill – most of the existing, worn asphalt pavement serves as a base for the UTWT, thus eliminating the need and expense to tear up and haul away the asphalt
Besides less cement consumption helps to earn Carbon credit and is lesser burden to environment.
Note: (1 ton of calcium carbonate the main raw product in manufacture of cement produces equivalent amount of carbon dioxide in atmosphere which is instrumental for global warming)
The world over to avoid the effect of global warming the use of flyash is giving the benefit if we can save carbon number.
In all the above mentioned contexts we should be given the chance to execute the above work in view of our experience in Thane and present work and the experimental patch at Pune.
Dr.Vilas.V.Deshmukh
Surface solutions Pvt. Ltd.
Cc
1 Vivek Kharwadkar, Addl.city engineer
2 Madhav Latkar, Development Engineer roads
Dr.V.V.Deshmukh
Managing Director
Surface Solutions Pvt.Ltd
Concrete technologies
Email vilasdes@gmail.com
Mobile 9869026667
To
Mr.Mahesh Zagade
The Commissioner
Pune Municipal Corporation
Sivaji Nagar
Pune 411005
Sub : UTWT at Bhosari colony in Pune city
Sir
The ULTRA THIN WHITE TOPPING (UTWT) which Pune Municipality is using for over lay to improve the damaged bituminous road is learnt by PMC Engineer along with contractor and consultant who visited our site in Thane which is developed by Dr.V.V.Deshmukh in consultation with Mr.P.Bongirwar. The same team have shown the successful demonstration to PMC engineer in Pune city.
Observing the performance of our work the Thane Municipality Corporation has sanctioned the budget of Rs 20 crores for UTWT to be used in city internal roads.
The present practice of that UTWT, which Pune Municipality Corporation is using, is not the correct technique and thereby not getting the expected benefits and this technique is optimised by us and proven from our experimental patch at Dahanukar Colony, Pune.
.
The following are the aspects that correct UTWT technology would help is
Cement use: one bag less per cubic meter which helps in reducing the carbon dioxide in the atmosphere and also the cost of surfacing. The idea of not using additive like fly ash, slag as substitute to cement is an old technique where as to achieve high strength we have to use this additive.
Use of fly ash: the fly ash, which is a by product of thermal power plant ,whose production of 100million tonnes per year and has problem of dumping., helps to be used as substitute to cement.
Process: the self compacted technique used by us in laying is faster and thus reducing times for unloading and completing the work faster. Use of machine
like vibrators for compaction is not required because of self compacting technique which is used by us. The mix which PMC is using is very harsh and takes two hours to unload where as our mix is semi self compacting and unloaded in half an hour.
The use of poly propylene strips helps to avoid cutting (1m X 1 m) , which results in less noise pollution and reduction of cost of Rs 100 per running meter.
The traffic can be opened in 72 hrs vs. 7 days, which reduces the inconvenience to pedestrians; less trouble to traffic diversion and traffic load to certain areas are avoided.
The above mentioned points are highlighted in light of correct UTWT technology which is today standardised by us
I also wish to highlight the following additional advantages of this UTWT technology.
Improved performance: The life of road is increased due use of UTWT than the bituminous road which saves maintenance cost and there is no rutting or wash boarding
In the recycle cost study it proves to be cheaper in the cycle of maintenance due to its longevity.
The light colour of the road increases illumino effect due to increased reflectivity and thereby reducing the heat content of the environment.
The less consumption of raw materials has direct bearing on the unit cost of the road surface laying.
Minimizes waste. Less material to landfill – most of the existing, worn asphalt pavement serves as a base for the UTWT, thus eliminating the need and expense to tear up and haul away the asphalt
Besides less cement consumption helps to earn Carbon credit and is lesser burden to environment.
Note: (1 ton of calcium carbonate the main raw product in manufacture of cement produces equivalent amount of carbon dioxide in atmosphere which is instrumental for global warming)
The world over to avoid the effect of global warming the use of flyash is giving the benefit if we can save carbon number.
In all the above mentioned contexts we should be given the chance to execute the above work in view of our experience in Thane and present work and the experimental patch at Pune.
Dr.Vilas.V.Deshmukh
Surface solutions Pvt. Ltd.
Cc
1 Vivek Kharwadkar, Addl.city engineer
2 Madhav Latkar, Development Engineer roads
Tuesday, July 27, 2010
mahesh zagade
/home/ashima/vilas/dr deshmukh/pune commissionar.doc
From 26th October 2009
Dr.V.V.Deshmukh
Managing Director
Surface Solutions Pvt.Ltd
Concrete technologies
Email vilasdes@gmail.com
Mobile 9869026667
To
Mr.Mahesh Zagade
The Commissioner
Pune Municipal Corporation
Sivaji Nagar
Pune 411005
Sub : UTWT at Bhosari colony in Pune city
Sir
The ULTRA THIN WHITE TOPPING (UTWT) which Pune Municipality is using for over lay to improve the damaged bituminous road is learnt by PMC Engineer along with contractor and consultant who visited our site in Thane which is developed by Dr.V.V.Deshmukh in consultation with Mr.P.Bongirwar. The same team have shown the successful demonstration to PMC engineer in Pune city.
Observing the performance of our work the Thane Municipality Corporation has sanctioned the budget of Rs 20 crores for UTWT to be used in city internal roads.
The present practice of that UTWT, which Pune Municipality Corporation is using, is not the correct technique and thereby not getting the expected benefits and this technique is optimised by us and proven from our experimental patch at Dahanukar Colony, Pune.
.
The following are the aspects that correct UTWT technology would help is
Cement use: one bag less per cubic meter which helps in reducing the carbon dioxide in the atmosphere and also the cost of surfacing. The idea of not using additive like fly ash, slag as substitute to cement is an old technique where as to achieve high strength we have to use this additive.
Use of fly ash: the fly ash, which is a by product of thermal power plant ,whose production of 100million tonnes per year and has problem of dumping., helps to be used as substitute to cement.
Process: the self compacted technique used by us in laying is faster and thus reducing times for unloading and completing the work faster. Use of machine
like vibrators for compaction is not required because of self compacting technique which is used by us. The mix which PMC is using is very harsh and takes two hours to unload where as our mix is semi self compacting and unloaded in half an hour.
The use of poly propylene strips helps to avoid cutting (1m X 1 m) , which results in less noise pollution and reduction of cost of Rs 100 per running meter.
The traffic can be opened in 72 hrs vs. 7 days, which reduces the inconvenience to pedestrians; less trouble to traffic diversion and traffic load to certain areas are avoided.
The above mentioned points are highlighted in light of correct UTWT technology which is today standardised by us
I also wish to highlight the following additional advantages of this UTWT technology.
Improved performance: The life of road is increased due use of UTWT than the bituminous road which saves maintenance cost and there is no rutting or wash boarding
In the recycle cost study it proves to be cheaper in the cycle of maintenance due to its longevity.
The light colour of the road increases illumino effect due to increased reflectivity and thereby reducing the heat content of the environment.
The less consumption of raw materials has direct bearing on the unit cost of the road surface laying.
Minimizes waste. Less material to landfill – most of the existing, worn asphalt pavement serves as a base for the UTWT, thus eliminating the need and expense to tear up and haul away the asphalt
Besides less cement consumption helps to earn Carbon credit and is lesser burden to environment.
Note: (1 ton of calcium carbonate the main raw product in manufacture of cement produces equivalent amount of carbon dioxide in atmosphere which is instrumental for global warming)
The world over to avoid the effect of global warming the use of flyash is giving the benefit if we can save carbon number.
In all the above mentioned contexts we should be given the chance to execute the above work in view of our experience in Thane and present work and the experimental patch at Pune.
Dr.Vilas.V.Deshmukh
Surface solutions Pvt. Ltd.
Cc
1 Vivek Kharwadkar, Addl.city engineer
2 Madhav Latkar, Development Engineer roads
From 26th October 2009
Dr.V.V.Deshmukh
Managing Director
Surface Solutions Pvt.Ltd
Concrete technologies
Email vilasdes@gmail.com
Mobile 9869026667
To
Mr.Mahesh Zagade
The Commissioner
Pune Municipal Corporation
Sivaji Nagar
Pune 411005
Sub : UTWT at Bhosari colony in Pune city
Sir
The ULTRA THIN WHITE TOPPING (UTWT) which Pune Municipality is using for over lay to improve the damaged bituminous road is learnt by PMC Engineer along with contractor and consultant who visited our site in Thane which is developed by Dr.V.V.Deshmukh in consultation with Mr.P.Bongirwar. The same team have shown the successful demonstration to PMC engineer in Pune city.
Observing the performance of our work the Thane Municipality Corporation has sanctioned the budget of Rs 20 crores for UTWT to be used in city internal roads.
The present practice of that UTWT, which Pune Municipality Corporation is using, is not the correct technique and thereby not getting the expected benefits and this technique is optimised by us and proven from our experimental patch at Dahanukar Colony, Pune.
.
The following are the aspects that correct UTWT technology would help is
Cement use: one bag less per cubic meter which helps in reducing the carbon dioxide in the atmosphere and also the cost of surfacing. The idea of not using additive like fly ash, slag as substitute to cement is an old technique where as to achieve high strength we have to use this additive.
Use of fly ash: the fly ash, which is a by product of thermal power plant ,whose production of 100million tonnes per year and has problem of dumping., helps to be used as substitute to cement.
Process: the self compacted technique used by us in laying is faster and thus reducing times for unloading and completing the work faster. Use of machine
like vibrators for compaction is not required because of self compacting technique which is used by us. The mix which PMC is using is very harsh and takes two hours to unload where as our mix is semi self compacting and unloaded in half an hour.
The use of poly propylene strips helps to avoid cutting (1m X 1 m) , which results in less noise pollution and reduction of cost of Rs 100 per running meter.
The traffic can be opened in 72 hrs vs. 7 days, which reduces the inconvenience to pedestrians; less trouble to traffic diversion and traffic load to certain areas are avoided.
The above mentioned points are highlighted in light of correct UTWT technology which is today standardised by us
I also wish to highlight the following additional advantages of this UTWT technology.
Improved performance: The life of road is increased due use of UTWT than the bituminous road which saves maintenance cost and there is no rutting or wash boarding
In the recycle cost study it proves to be cheaper in the cycle of maintenance due to its longevity.
The light colour of the road increases illumino effect due to increased reflectivity and thereby reducing the heat content of the environment.
The less consumption of raw materials has direct bearing on the unit cost of the road surface laying.
Minimizes waste. Less material to landfill – most of the existing, worn asphalt pavement serves as a base for the UTWT, thus eliminating the need and expense to tear up and haul away the asphalt
Besides less cement consumption helps to earn Carbon credit and is lesser burden to environment.
Note: (1 ton of calcium carbonate the main raw product in manufacture of cement produces equivalent amount of carbon dioxide in atmosphere which is instrumental for global warming)
The world over to avoid the effect of global warming the use of flyash is giving the benefit if we can save carbon number.
In all the above mentioned contexts we should be given the chance to execute the above work in view of our experience in Thane and present work and the experimental patch at Pune.
Dr.Vilas.V.Deshmukh
Surface solutions Pvt. Ltd.
Cc
1 Vivek Kharwadkar, Addl.city engineer
2 Madhav Latkar, Development Engineer roads
Sunday, July 11, 2010
flyash grout
Grout using black colour Tata flyash
% Rate/kg cost
Cement 20 3.5 0.7
tata black flyash 80 0.75 0.6
suparex 0.75 73 0.5
1.8
% Rate/kg cost
Cement 20 3.5 0.7
tata black flyash 80 0.75 0.6
suparex 0.75 73 0.5
1.8
activation of flyash
Dear Mr Dekmush,
do you mean European standards then its EN 197?
I have not done alkali activation of fly ash myself and its not done in
Holcim yet but I have done a literature review, the summary I have
attached. To activate Class F fly ash as in India will be quite difficult
as its a relatively coarse and low reactiv fly ash. You need high
percentages of activators which might cause problems with regards to
standard limits on Cl and alkalies and in application e.g. corrosion and
ASR reaction. Therefore we will test this new combination of grinding aids
and quality improvers from South Africa as send to you as it seems to work
quite well. Fly ash content could be increased from 32 to 38% at same
perfomance.
Economically its difficult to say if grinding or activation is more
economic as it depends on the % and type of activator and the Blaine.
Grinding has a certain limit for activation of fly ash cement as beyond
around 4000 Blaine the activation effect through surface increase is
compensated by higher water demand in the concrete. So beyond a certain fly
ash content it should be probably a combination of both mechanical and
chemical activation. The cheapest activator is NaCl which mainhly acts on
the clinker, NaOH is more fly ash specific but also more costly.
Coarse fly ashes with a high reactive SiO2 content >30% react very well on
grinding, we have seen it in some of our Eastern European plants.
Another promising option are multiple blends like fly ash/slag or fly
ash/limestone blends. They combine very well and when ground separately
fineness of the components can be adjusted to maximise performance. But I
think the IS does not allow it right now, may be in the future.
Generally you can say its possible to activate each fly ash its just a
matter of concentration and thats also the problem. The majority of R&D was
on either activation via suspension or at elevated temperatures or US
specific Class C fly ashes were used which have cement like properties,
there are Class C fly ash based binders in US marketed as shown in the
file. Except HolcimAct admixture which should work also with your
clinker/FA, I do not see a magic powder which will push the fly ash
activity, I see more a combination of measures be it even another grinding
system like vibrating mills, one large scale operational in Texas and use
of certain activators partially activating the clinker and partially
activating fly ash. May be it should be also mentioned that Lafarge did
tests with injecting HCl in the finished mill to activate fly ash by
etching the surface of fly ash particles but problem in this case was
corrosion of mill parts. Another option of course would be air
classification of fly ash to increase fineness and thus reactivitiy but
this requires CAPEX and has about 5USD/t operation cost and you have to
take care of the residue as well.
So all together I do not have a final solution, sorry. I would certainly
start with HolcimAct first and see if it works.
What is your current project and program and what are the targets you want
to achieve?
Best regards
Stefan Dietz
(See attached file: Fly_ash_maximation Holcim.ppt)(See attached file: EN
197-1 en.pdf)(See attached file: Fly ash standards.ppt)
_____________________
Stefan Dietz
Holcim Group Support Ltd
Corporate Commercial Services
Product Innovation and Development
Im Schachen
5113 Holderbank
Phone +41 58 858 64 12
Fax +41 58 858 64 09
Mobile +41 79 373 7983
stefan.dietz@holcim.com
www.holcim.com
This e-mail is confidential and intended only for the use of the above
named addressee. If you have received this e-mail in error, please delete
it immediately and notify us by e-mail or telephone.
do you mean European standards then its EN 197?
I have not done alkali activation of fly ash myself and its not done in
Holcim yet but I have done a literature review, the summary I have
attached. To activate Class F fly ash as in India will be quite difficult
as its a relatively coarse and low reactiv fly ash. You need high
percentages of activators which might cause problems with regards to
standard limits on Cl and alkalies and in application e.g. corrosion and
ASR reaction. Therefore we will test this new combination of grinding aids
and quality improvers from South Africa as send to you as it seems to work
quite well. Fly ash content could be increased from 32 to 38% at same
perfomance.
Economically its difficult to say if grinding or activation is more
economic as it depends on the % and type of activator and the Blaine.
Grinding has a certain limit for activation of fly ash cement as beyond
around 4000 Blaine the activation effect through surface increase is
compensated by higher water demand in the concrete. So beyond a certain fly
ash content it should be probably a combination of both mechanical and
chemical activation. The cheapest activator is NaCl which mainhly acts on
the clinker, NaOH is more fly ash specific but also more costly.
Coarse fly ashes with a high reactive SiO2 content >30% react very well on
grinding, we have seen it in some of our Eastern European plants.
Another promising option are multiple blends like fly ash/slag or fly
ash/limestone blends. They combine very well and when ground separately
fineness of the components can be adjusted to maximise performance. But I
think the IS does not allow it right now, may be in the future.
Generally you can say its possible to activate each fly ash its just a
matter of concentration and thats also the problem. The majority of R&D was
on either activation via suspension or at elevated temperatures or US
specific Class C fly ashes were used which have cement like properties,
there are Class C fly ash based binders in US marketed as shown in the
file. Except HolcimAct admixture which should work also with your
clinker/FA, I do not see a magic powder which will push the fly ash
activity, I see more a combination of measures be it even another grinding
system like vibrating mills, one large scale operational in Texas and use
of certain activators partially activating the clinker and partially
activating fly ash. May be it should be also mentioned that Lafarge did
tests with injecting HCl in the finished mill to activate fly ash by
etching the surface of fly ash particles but problem in this case was
corrosion of mill parts. Another option of course would be air
classification of fly ash to increase fineness and thus reactivitiy but
this requires CAPEX and has about 5USD/t operation cost and you have to
take care of the residue as well.
So all together I do not have a final solution, sorry. I would certainly
start with HolcimAct first and see if it works.
What is your current project and program and what are the targets you want
to achieve?
Best regards
Stefan Dietz
(See attached file: Fly_ash_maximation Holcim.ppt)(See attached file: EN
197-1 en.pdf)(See attached file: Fly ash standards.ppt)
_____________________
Stefan Dietz
Holcim Group Support Ltd
Corporate Commercial Services
Product Innovation and Development
Im Schachen
5113 Holderbank
Phone +41 58 858 64 12
Fax +41 58 858 64 09
Mobile +41 79 373 7983
stefan.dietz@holcim.com
www.holcim.com
This e-mail is confidential and intended only for the use of the above
named addressee. If you have received this e-mail in error, please delete
it immediately and notify us by e-mail or telephone.
Friday, July 9, 2010
About Flyash
Fy ash is one of the residues generated in the combustion of coal. Fly ash is generally captured from the chimneys of coal-fired power plants, and is one of two types of ash that jointly are known as coal ash; the other, bottom ash, is removed from the bottom of coal furnaces. Depending upon the source and makeup of the coal being burned, the components of fly ash vary considerably, but all fly ash includes substantial amounts of silicon dioxide (SiO2) (both amorphous and crystalline) and calcium oxide (CaO), both being endemic ingredients in many coal bearing rock strata.
Toxic constituents depend upon the specific coal bed makeup, but may include one or more of the following elements or substances in quantities from trace amounts to several percent: arsenic, beryllium, boron, cadmium, chromium, chromium VI, cobalt, lead, manganese, mercury, molybdenum, selenium, strontium, thallium, and vanadium, along with dioxins and PAH compounds.
more on flyash -
http://en.wikipedia.org/wiki/Fly_ash
Role of Flyash in Sustainable Development
Concrete, Flyash, and the Environment - Proceedings
A forum held 8 December 1998 - Sponsored by EHDD Architecture and Pacific Energy Center
Role of Flyash in Sustainable Development
P.K. Mehta
Good evening, it's very nice to see so many of my friends here. You have heard a very eloquent presentation that we all have a responsibility to do something about global warming. All of us, architects, structural engineers, designers and others, we participate in decision making about concrete mix design, the quality of concrete, and it is here that we can do something about global warming. As was mentioned earlier, each ton of portland cement we consume throws out into the environmental loading about one ton of CO2. So if we are producing 1.3 billion tons of portland cement annually, this emits 1.3 billion tons of CO2 into the environment.
And in 25 years we expect that the demand for portland cement in the world will double up. This is because the developing countries with large populations and rapid population growth, mostly in Asia, South America and Africa, where about 5 billion of the globe's 6 billion people live, still have a long way to go in terms of socioeconomic development. And you cannot tell them "please do not do what the developed countries have done to achieve a high standard of living." They require just as we do, reasonably decent housing for their children, reasonably decent roadways for travel, etc. With globalization of technology and economy, their aspirations are very high; every country wants its citizens to participate in an affluent lifestyle.
So there is no way to stop the demand for more concrete. But any additional portland cement clinker capacity that we build is going to load the environment with an additional one ton of CO2 per ton of cement. There is no shortcut, there is no way around it, half of the CO2 comes from the decomposition of limestone, which is a major raw material for making portland cement, and half of it comes from the fuel. Since coal is the cheapest fuel, we are going to continue to use it for making portland cement. The question is can we continue to meet the increasing demand for cement and concrete in a sustainable manner.
Fortunately, within this scenario a new player has emerged that can save us. And that player is flyash. There are some problems because most of the literature on flyash, research on flyash, and the flyash codes are obsolete. They are not updated, and it will take time to do so.
Meanwhile, let's look at the current materials, and the current science and technology. Let's satisfy ourselves intellectually and with the help of some laboratory work, some field tests, and some real buildings; and it's our hope that we can solve the problem.
With this background, my job is to give you a brief introduction as to what flyash is and what flyash can do in concrete today, based on the current state of our knowledge. Although many of you know about flyash, my effort will be to take even those who don't know anything about flyash right from ground level to the latest that we know about it. I will first spend a few minutes talking about the source, because typically people don't know about it.
One of the important issues I will describe are the mechanisms by which flyash influences the properties of concrete. Because if you understand the mechanism, you don't have to worry about codes and standards. Once you have a good understanding of the way things work, you can be courageous enough to take some steps. So I'll dwell on mechanisms, and finally give you a brief introduction to the very latest developments, which 10 years from now will probably become a part of conventional concrete technology.
Characteristics of Flyash
Flyash is a powdery substance obtained from dust collectors, whether they are electrical precipitators or baghouses, in electrical power plants which use ground coal as fuel. The U.S. produces about 60 million tons per year, some say 55 million, some say 50, but I've been hearing 55 million for about the last 10 years so it must be 60 million tons. Because of many of the stigmas attached to flyash, the consumption of flyash in the cement and concrete industry is no more that 6 million tons which is only about 10%. And once I tell you what flyash can do, I think that it's a disgrace that most of it is ending up in the landfills, creating lots of problems with our groundwater, air, and land.
The physical and chemical characteristics of flyash which I'm going to discuss, and their effect on the properties of concrete are mainly from an EPRI Report based on a study funded by EPRI [The Electric Power Research Institute] in the early 1980is at UC Berkeley where I work. I was the principal investigator on the research project. My comments are based on not one flyash, but on about 20 U.S. flyashes from the East Coast, the Midwest, the State of Washington, and from Canada; so it's representative of most flyashes, and this report is available from EPRI as report CS3314, published in January 1984. Most of my comments about the characteristics of flyash are based on this source.
Flyash Chemistry
First, unfortunately, the codes, ASTM and so forth, have a very heavy emphasis on the chemistry of flyash. For example "Class F flyash must have more than 70% total of silica, alumina, and iron oxide, and Class C has more than 50% of these oxides" etc. And people get confused because there is really no direct relation between the chemistry of flyash and the properties in concrete. Most of the properties of flyash in concrete are determined by the flyash mineralogy and particle size, and not by chemistry. Don't worry about these various chemical percentages, there is a big range and this range doesn't mean anything. I'm just showing the range to show you that there is a lot of variability, and people get worried about variability. They worry that "what if today I'm getting flyash with 48% silica and tomorrow it goes to 44%". It's not important, nothing will happen.
Flyash Mineralogy
Most important is the flyash mineralogy, and with regard to the mineralogy of flyash, 60-90% is glass. It starts out as impurities in coal, mostly clays, shales, limestone, and dolomite. They cannot be burned so they end up as ash, and at high temperatures they fuse and become glass. Because of the high speed of the flue gases, the molten glass turns into glass beads, or tiny spheres of glass. I'm emphasizing this because it's the kind of material if we didn't have it, we would have to invent it in order to improve the workability and durability of concrete.
For flyash in the U.S., there are two ASTM Classes, Class F and Class C that are based on total amounts of silica, alumina, and iron oxide present. This doesn't have much significance. In Europe and the rest of the world there is a recognition that if you want to make some differentiation based on the chemistry, then divide flyash based on it's calcium content, because the calcium content of flyash has a great influence on the type of glass. And if a material is mostly glass, we should only be worrying about what kind of glass it is. There is too much emphasis on the remaining stuff that is not glass. Remember flyash is 60-90% glass, and modern flyashes are much closer to 70-80% glass.
Low calcium flyash also contains non-reactive crystalline minerals; say you have 80% glass, with the 20% remaining being a non-reactive mineral like quartz, mullite, which is an aluminum silicate, hematite and magnetite, which are iron oxides, and a less reactive alumino silicate glass. There are two glass types. If you have high calcium flyash then the alumino silicate glass has also a lot of calcium in it and that glass is more reactive. So that's why Class C flyash gives you higher early strength compared to Class F, because Class C tends to have much more calcium oxide. High calcium flyashes also contain reactive crystalline minerals such as free lime, tri-calcium aluminate, tetra-calcium alumino-sulfate, and calcium sulfate, depending on the sulfur content of the ash. And all of these are reactive crystalline minerals and the glass is also much more reactive.
Flyash Particle Size
There are two parameters that determine the reactivity of flyash, one is the mineralogy, and the second is the particle characteristics. Now you should pay very careful attention to the particle characteristics. Particles are mostly glassy, solid and spherical. There are some hollow cenospheres and so forth, but let's not spend time on that because most important is that most of the flyash consists of glassy particles that are solid and spherical. There is also some unburned carbon present, depending on the efficiency of burning. Today's furnaces are very efficient; you may have only 1% carbon, and this carbon is in the form of highly micro-porous large particles, they are just like Swiss cheese, they are large but are not round or spherical because they are not a molten material, it's like charcoal or coke.
The particles of flyash range in size from 1 to 100 microns (1,000 microns is 1 mm, so this largest size particle, 100 microns, equals 0.1 mm). The average size is about 20 microns which is similar to portland cement average particle size. Now what is more important for you to remember is that more that 40% of the particles are under 10 microns, and particles under 10 microns, regardless of the type of flyash, are the ones that contribute to the 7 and 28 day strengths. Under 10 microns is the magic number. And particles about 45 microns and larger, which is 325 sieve residue may be considered as inert. They do not participate in pozzolanic reactions, even after one year, so they behave like sand.
So with flyash, don't worry about the Blaine surface area. What is most important is the particle size distribution. Particles below 10 microns are the ones which are really beneficial for early strength. Particles about 45 microns and larger are not so useful. Between 10 and 45 microns are the ones that slowly react between 28 days and one year or so. Most flyashes have less than 15 or 20% particles which are above 45 microns, and more than 40% particles which are under 10 microns.
In the EPRI study we also worried about whether the furnace design would have any affect on the reactivity of flyash, but we found that the furnace design did not affect flyash reactivity. We found that modern furnaces generally produce a flyash that is low in carbon. ASTM has a 6% limit on carbon in flyash used in concrete, but flyash produced today typically contains 1.0% to 1.5% carbon. And today's flyashes are high in glass, they are 80-90% glass, and have good reactivity. A flyash of this composition will have a good reactivity when its composed of a large proportion of fine particles. So don't go by the residue of the 325 mesh; it only tells you the particles which are inert. To judge flyash reactivity, you will have to find out what percentage of the particles are below 10 microns.
What is the significance of any unburned carbon particles? Unburned carbon particles influence mostly the water demand and the air entraining agent required. In the East Coast and the Midwest where concrete is exposed to freezing & thawing cycles, there is always air entrainment in concrete. In this case, the carbon content is something to worry about because it would influence the dosage of the air entraining admixture.
Again, to continue the conclusions from the EPRI study, we found that except for calcium, flyash chemistry has little influence on reactivity. So except for calcium, don't worry about silica, alumina, iron oxide, etc., they have nothing to do with the properties. The superior reactivity of high calcium flyashes is related to the composition of glass and the presence of reactive crystalline phases.
How Flyash Works
Now that you have learned about what flyash is, let's look at how it works. The first equation in the illustration (see figure 2.2) shows you the chemistry of hydration of portland cement. About 50% of portland cement is composed of the primary mineral tri-calcium silicate, which on hydration forms calcium silicate hydrate and calcium hydroxide. If you have a portland-pozzolan cement, and flyash is the pozzolan, it can be represented by silica because non-crystalline silica glass is the principal constituent of flyash. The silica combines with the calcium hydroxide released on the hydration of portland cement. Calcium hydroxide in hydrated portland cement does not do anything for strength, so therefore you use it up with reactive silica. Slowly and gradually it forms additional calcium silicate hydrate which is a binder, and which fills up the space, and gives you impermeability and more and more strength. This is how the chemistry works.
Figure 2.1 Photograph of flyash enlarged many times
Figure 2.2 Flyash combines with excess and unwanted large crystals of calcium hydroxide (CH) to form additional useful binder (C-S-H)
Now in order to understand the benefits of flyash use we have to look at the physical manifestations of the chemical reaction. There is something called a transition zone in concrete. So far we have looked only at the cement paste, but in concrete you have sand and gravel, and many properties of concrete are controlled by the strength of the interfacial bond between the aggregate and the cement paste, and that interfacial bond is called the transition zone. The transition zone in portland cement concrete is very weak because of the presence of large crystals of calcium hydroxide which find space here due to the wall effect next to the coarse aggregate particles. You can see very clearly in the slide, these large calcium hydroxide crystals, they do not really bind with the aggregate, and they can be easily detached and cracked. And it is these cracks which are the ones that are responsible for the lack of impermeability, or lack of water tightness in concrete. So if you are able to build a stronger transition zone, then you can eliminate micro-cracking, and improve the impermeability, as well as improve the chemical durability, and thus end up with a highly durable concrete.
Also, the particles of coarse aggregate, due to the wall effect, tend to trap water next to the aggregate, and therefore what you see on the surface of the concrete as the visible bleed water is only part of the mixing water. A large amount of mixing water ends up as a locally high water-cement ratio type of cement paste next to the aggregate particles. When you vibrate concrete this is what happens: you have part of the extra mixing water on the surface as the visible bleed water, and a very large amount of bleed water due to internally trapped water next to the coarse aggregate.
The next slide shows you what happens (see figure 2.3). As a result of local high water cement ratio paste next to the coarse aggregate, you form the large crystals of calcium hydroxide, very large crystals, and you have large pores left over making this an area of weakness. If there is any stress, if there is any drying shrinkage, any thermal shrinkage, any loading and unloading effect, then these stress effects could very easily rupture the concrete. It would rupture next to the coarse aggregate particles because of the high porosity, and because this area is filled up with something which is not very strong, these are large plates of calcium hydroxide which can be cracked very easily.
The next slide shows you that this is what actually happens in the field. (see figure 2.4). From a thin section of concrete that deteriorated in a few years, you can trace the micro-cracks with a fluorescent dye. Sea water or de-icing chemicals can permeate very easily through these micro cracks, many of which are interconnected with the cracks which exist next to the aggregate particles. Most of the causes for lack of durability of reinforced concrete, whether it's alkali aggregate reaction, or the corrosion of steel, or sulfate attack, they can be very easily linked to the permeability of concrete, to its lack of water tightness. And this lack of water tightness is not there in freshly cured concrete; it comes later due to environmental effects: heating and cooling, wetting and drying, and because you have built in areas of weakness which micro-crack very easily. When these micro-cracks interconnect, you have channels of flow from outside, and that's how the aggressive chemicals get into the concrete.
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Figure 2.3 Large calcium hydroxide crystals create a plane of weakness next to the coarse aggregate
Figure 2.4 Cross section of concrete showing interconnected micro-cracks adjacent to coarse aggregate.
CANMET Research
Next slide. There are two recent developments regarding high volume flyash concrete, one is the CANMET study which I mentioned earlier, and I want to show you some of the results using these mixes, and how they work. What happens to the voids in the transition zone if you increase the portland cement content of the concrete mixtures? The fine particles of cement in the internal bleed water would dissolve and you will still have voids although smaller in size. Now imagine what would happen if, instead of using the more reactive material (that is portland cement), you add fine particles of a less reactive material such as flyash and also reduce the water content of the concrete mix. You will end up with a less porous transition zone because these tiny glass beads of flyash will obstruct the channels of flow and will make the water-cement ratio more homogeneous in concrete by preventing the formation of local bleed water. And this is exactly what CANMET has found, by limiting the water content, and by introducing a large amount of flyash in the concrete mix. In this mix (see figure 2.5) there is 60% or 215 kg per cubic meter of flyash (360#/CY), 120 kg of mixing water (200#/CY), and 150 kg of cement (260#/CY). The water to cementitious ratio is limited to 0.32 due to the use of a super plasticizer, as well as due to air entrainment which is always required in Canada. So this is a typical CANMET mix, and the next slide shows the properties.
The bleeding with this mix ranges from very low to negligible due to the very low water content of this type of concrete, and also due to the obstruction of channels of flow, you don't expect bleeding on the surface. One of the negative side effects of this is, that you have to take proper care to prevent plastic shrinkage cracking. There are a lot of benefits to this material, but you will also have to learn about the negatives, what is the flip side of the coin. The flip side of the coin is you don't have the luxury of too much bleed water. The construction workers cannot take a coffee break and go away until the sheen is gone, and then come back and finish it. Because there is no sheen to go away, there is no bleed water at all, so you have to be aware of that.
Next slide. With the CANMET mix, the setting time is somewhat longer because remember, the cement content is less that 300 pounds here, and it is the cement that hydrates very, very quickly. It is the hydration of cement that forms calcium silicate hydrate, and as these fibers of calcium silicate hydrate grow, they tend to weave into each other and give you the time of set and strength. So if the cement content is low, naturally the time of set will be slow. But in general, the experience both from the laboratory and the field mixture is that high volume flyash concrete does not show unacceptable retardation in setting time, and demonstrates enough strength development to produce adequate strength at one day. They have obtained 10 MPa (1,500 psi) strength at one day in many of these mixes.
Next slide. Another very important advantage of flyash in concrete is the reduction of thermal cracking. Well known structural engineers who have been in the business for a long time, Professor T.Y. Lin, Professor Ben Gerwick, from their field experience can tell you that many of the problems in concrete are due to thermal cracking. Heat of hydration impacts are usually only considered in mass concrete, such as massive dams. But even in structures which are much less massive, only two or three feet thick, it is massive enough to accumulate enough heat of hydration to cause thermal cracking. So CANMET did a study on 10 foot x 10 foot x 10 foot cubes with a high volume flyash mix. Using this mix the temperature rise was only 35 degrees C compared to 65 degrees C in the control mix using only portland cement. This is a very significant advantage for the durability of concrete because thermal cracking would reduce the watertightness.
The typical compressive strengths that we get with this mix (see figure 2.6) is 8-10 MPa at one day, 35 MPa at 28 days, about 43 MPa at 91 days, and about 55 MPa at one year.
Next slide. Very important from the standpoint of sustainable development is the durability of structures. A lot of structural damage, especially in reinforced concrete, occurs due to the corrosion of steel. There is an ASTM test, rapid chloride penetration test ASTM C1202, where at 28 days 500 to 2,000 coulomb rating was found for the CANMET mixes (see figure 2.7). There is a table showing that anything less than 2,000 coulombs is a very low permeability concrete, so the permeability to CO2, and to chlorides which are responsible for the corrosion of steel is very low in the high volume flyash concrete. And this coulomb rating continues to improve, because many flyash particles react very slowly, pushing the coulomb value lower and lower.
A field test was undertaken by the University of Toronto. Preliminary data is shown in the next slide (courtesy of Professor Michael Thomas). In ten years you can see that the chloride penetration is negligible at about 1 inch depth of cover if you have 50% flyash in the concrete mix. It is an ongoing study in a tidal zone exposed to sea water, with 25 MPA concrete.
The next slide shows another advantage, this is based on a study by Professor Schiessl at the University of Aachen. In Europe they are very much concerned about dumping of industrial by-products because of the potential for ground water contamination. Flyash contains very small amounts of toxic elements, so they wanted to find out about the potential for the leaching of elements such as zinc, chromium, etc. Schiessl and his coworkers found out in the study that flyash concrete is very effective at immobilizing even externally added heavy metals in mortars. Test B is not a very good test, test C is the correct test for mortars and concrete, it is called the tank test and is a leach test on uncrushed specimens. They introduced into the mix, 185 mg of zinc per kg of mix. Then in the leach test they could only leach out 0.09 mg in 56 days. So it's not only that flyash concrete would prevent outside ions from getting in, but it also keeps whatever is in the concrete all tied up, it will not permit it to get out. If you have a toxic metal that has been immobilized by using flyash in concrete, rest assured that it will stay there. In the case of chromium from 53 mg of added chromium, only 0.15 mg could be leached out from the flyash mortar specimens.
Next slide. So this is the mix for the future. In the future, because of so many of these advantages, and much concern about sustainable development, we'll have not only portland cement in the concrete mix, we'll have silica fume and other pozzolans. And in this witches brew a super plasticizer, an air entraining admixture, or other chemical admixtures may be incorporated. This is the future.
Let me go back to a few more transparencies and then I'll finish. I mentioned the ASTM C1202 which is based on AASHTOis T277 test. A 1,000 to 2,000 coulombs current flow in a 6 hour test is a rating of low chloride permeability (see figure 2.8). This is usually a portland cement concrete with less than a 0.4 water cement ratio. If you want very low permeability, less than 1,000 coulomb rating, this is typical of an internally sealed pore system such as with a latex modified concrete. Such low permeability ratings can be obtained with ternary cement blends which I will discuss next.
Chloride Permeability Ratings per AASHTO T-277
Charge Passed
coulombs
Chloride Permeability
Typical of:
> 4000
High
Portland Cement Concrete
W/C > 0.6
2000 - 4000
Moderate
Portland Cement Concrete
0.4 < W/C < 0.6
1000 - 2000
Low
Portland Cement Concrete
W/C < 0.4
A forum held 8 December 1998 - Sponsored by EHDD Architecture and Pacific Energy Center
Role of Flyash in Sustainable Development
P.K. Mehta
Good evening, it's very nice to see so many of my friends here. You have heard a very eloquent presentation that we all have a responsibility to do something about global warming. All of us, architects, structural engineers, designers and others, we participate in decision making about concrete mix design, the quality of concrete, and it is here that we can do something about global warming. As was mentioned earlier, each ton of portland cement we consume throws out into the environmental loading about one ton of CO2. So if we are producing 1.3 billion tons of portland cement annually, this emits 1.3 billion tons of CO2 into the environment.
And in 25 years we expect that the demand for portland cement in the world will double up. This is because the developing countries with large populations and rapid population growth, mostly in Asia, South America and Africa, where about 5 billion of the globe's 6 billion people live, still have a long way to go in terms of socioeconomic development. And you cannot tell them "please do not do what the developed countries have done to achieve a high standard of living." They require just as we do, reasonably decent housing for their children, reasonably decent roadways for travel, etc. With globalization of technology and economy, their aspirations are very high; every country wants its citizens to participate in an affluent lifestyle.
So there is no way to stop the demand for more concrete. But any additional portland cement clinker capacity that we build is going to load the environment with an additional one ton of CO2 per ton of cement. There is no shortcut, there is no way around it, half of the CO2 comes from the decomposition of limestone, which is a major raw material for making portland cement, and half of it comes from the fuel. Since coal is the cheapest fuel, we are going to continue to use it for making portland cement. The question is can we continue to meet the increasing demand for cement and concrete in a sustainable manner.
Fortunately, within this scenario a new player has emerged that can save us. And that player is flyash. There are some problems because most of the literature on flyash, research on flyash, and the flyash codes are obsolete. They are not updated, and it will take time to do so.
Meanwhile, let's look at the current materials, and the current science and technology. Let's satisfy ourselves intellectually and with the help of some laboratory work, some field tests, and some real buildings; and it's our hope that we can solve the problem.
With this background, my job is to give you a brief introduction as to what flyash is and what flyash can do in concrete today, based on the current state of our knowledge. Although many of you know about flyash, my effort will be to take even those who don't know anything about flyash right from ground level to the latest that we know about it. I will first spend a few minutes talking about the source, because typically people don't know about it.
One of the important issues I will describe are the mechanisms by which flyash influences the properties of concrete. Because if you understand the mechanism, you don't have to worry about codes and standards. Once you have a good understanding of the way things work, you can be courageous enough to take some steps. So I'll dwell on mechanisms, and finally give you a brief introduction to the very latest developments, which 10 years from now will probably become a part of conventional concrete technology.
Characteristics of Flyash
Flyash is a powdery substance obtained from dust collectors, whether they are electrical precipitators or baghouses, in electrical power plants which use ground coal as fuel. The U.S. produces about 60 million tons per year, some say 55 million, some say 50, but I've been hearing 55 million for about the last 10 years so it must be 60 million tons. Because of many of the stigmas attached to flyash, the consumption of flyash in the cement and concrete industry is no more that 6 million tons which is only about 10%. And once I tell you what flyash can do, I think that it's a disgrace that most of it is ending up in the landfills, creating lots of problems with our groundwater, air, and land.
The physical and chemical characteristics of flyash which I'm going to discuss, and their effect on the properties of concrete are mainly from an EPRI Report based on a study funded by EPRI [The Electric Power Research Institute] in the early 1980is at UC Berkeley where I work. I was the principal investigator on the research project. My comments are based on not one flyash, but on about 20 U.S. flyashes from the East Coast, the Midwest, the State of Washington, and from Canada; so it's representative of most flyashes, and this report is available from EPRI as report CS3314, published in January 1984. Most of my comments about the characteristics of flyash are based on this source.
Flyash Chemistry
First, unfortunately, the codes, ASTM and so forth, have a very heavy emphasis on the chemistry of flyash. For example "Class F flyash must have more than 70% total of silica, alumina, and iron oxide, and Class C has more than 50% of these oxides" etc. And people get confused because there is really no direct relation between the chemistry of flyash and the properties in concrete. Most of the properties of flyash in concrete are determined by the flyash mineralogy and particle size, and not by chemistry. Don't worry about these various chemical percentages, there is a big range and this range doesn't mean anything. I'm just showing the range to show you that there is a lot of variability, and people get worried about variability. They worry that "what if today I'm getting flyash with 48% silica and tomorrow it goes to 44%". It's not important, nothing will happen.
Flyash Mineralogy
Most important is the flyash mineralogy, and with regard to the mineralogy of flyash, 60-90% is glass. It starts out as impurities in coal, mostly clays, shales, limestone, and dolomite. They cannot be burned so they end up as ash, and at high temperatures they fuse and become glass. Because of the high speed of the flue gases, the molten glass turns into glass beads, or tiny spheres of glass. I'm emphasizing this because it's the kind of material if we didn't have it, we would have to invent it in order to improve the workability and durability of concrete.
For flyash in the U.S., there are two ASTM Classes, Class F and Class C that are based on total amounts of silica, alumina, and iron oxide present. This doesn't have much significance. In Europe and the rest of the world there is a recognition that if you want to make some differentiation based on the chemistry, then divide flyash based on it's calcium content, because the calcium content of flyash has a great influence on the type of glass. And if a material is mostly glass, we should only be worrying about what kind of glass it is. There is too much emphasis on the remaining stuff that is not glass. Remember flyash is 60-90% glass, and modern flyashes are much closer to 70-80% glass.
Low calcium flyash also contains non-reactive crystalline minerals; say you have 80% glass, with the 20% remaining being a non-reactive mineral like quartz, mullite, which is an aluminum silicate, hematite and magnetite, which are iron oxides, and a less reactive alumino silicate glass. There are two glass types. If you have high calcium flyash then the alumino silicate glass has also a lot of calcium in it and that glass is more reactive. So that's why Class C flyash gives you higher early strength compared to Class F, because Class C tends to have much more calcium oxide. High calcium flyashes also contain reactive crystalline minerals such as free lime, tri-calcium aluminate, tetra-calcium alumino-sulfate, and calcium sulfate, depending on the sulfur content of the ash. And all of these are reactive crystalline minerals and the glass is also much more reactive.
Flyash Particle Size
There are two parameters that determine the reactivity of flyash, one is the mineralogy, and the second is the particle characteristics. Now you should pay very careful attention to the particle characteristics. Particles are mostly glassy, solid and spherical. There are some hollow cenospheres and so forth, but let's not spend time on that because most important is that most of the flyash consists of glassy particles that are solid and spherical. There is also some unburned carbon present, depending on the efficiency of burning. Today's furnaces are very efficient; you may have only 1% carbon, and this carbon is in the form of highly micro-porous large particles, they are just like Swiss cheese, they are large but are not round or spherical because they are not a molten material, it's like charcoal or coke.
The particles of flyash range in size from 1 to 100 microns (1,000 microns is 1 mm, so this largest size particle, 100 microns, equals 0.1 mm). The average size is about 20 microns which is similar to portland cement average particle size. Now what is more important for you to remember is that more that 40% of the particles are under 10 microns, and particles under 10 microns, regardless of the type of flyash, are the ones that contribute to the 7 and 28 day strengths. Under 10 microns is the magic number. And particles about 45 microns and larger, which is 325 sieve residue may be considered as inert. They do not participate in pozzolanic reactions, even after one year, so they behave like sand.
So with flyash, don't worry about the Blaine surface area. What is most important is the particle size distribution. Particles below 10 microns are the ones which are really beneficial for early strength. Particles about 45 microns and larger are not so useful. Between 10 and 45 microns are the ones that slowly react between 28 days and one year or so. Most flyashes have less than 15 or 20% particles which are above 45 microns, and more than 40% particles which are under 10 microns.
In the EPRI study we also worried about whether the furnace design would have any affect on the reactivity of flyash, but we found that the furnace design did not affect flyash reactivity. We found that modern furnaces generally produce a flyash that is low in carbon. ASTM has a 6% limit on carbon in flyash used in concrete, but flyash produced today typically contains 1.0% to 1.5% carbon. And today's flyashes are high in glass, they are 80-90% glass, and have good reactivity. A flyash of this composition will have a good reactivity when its composed of a large proportion of fine particles. So don't go by the residue of the 325 mesh; it only tells you the particles which are inert. To judge flyash reactivity, you will have to find out what percentage of the particles are below 10 microns.
What is the significance of any unburned carbon particles? Unburned carbon particles influence mostly the water demand and the air entraining agent required. In the East Coast and the Midwest where concrete is exposed to freezing & thawing cycles, there is always air entrainment in concrete. In this case, the carbon content is something to worry about because it would influence the dosage of the air entraining admixture.
Again, to continue the conclusions from the EPRI study, we found that except for calcium, flyash chemistry has little influence on reactivity. So except for calcium, don't worry about silica, alumina, iron oxide, etc., they have nothing to do with the properties. The superior reactivity of high calcium flyashes is related to the composition of glass and the presence of reactive crystalline phases.
How Flyash Works
Now that you have learned about what flyash is, let's look at how it works. The first equation in the illustration (see figure 2.2) shows you the chemistry of hydration of portland cement. About 50% of portland cement is composed of the primary mineral tri-calcium silicate, which on hydration forms calcium silicate hydrate and calcium hydroxide. If you have a portland-pozzolan cement, and flyash is the pozzolan, it can be represented by silica because non-crystalline silica glass is the principal constituent of flyash. The silica combines with the calcium hydroxide released on the hydration of portland cement. Calcium hydroxide in hydrated portland cement does not do anything for strength, so therefore you use it up with reactive silica. Slowly and gradually it forms additional calcium silicate hydrate which is a binder, and which fills up the space, and gives you impermeability and more and more strength. This is how the chemistry works.
Figure 2.1 Photograph of flyash enlarged many times
Figure 2.2 Flyash combines with excess and unwanted large crystals of calcium hydroxide (CH) to form additional useful binder (C-S-H)
Now in order to understand the benefits of flyash use we have to look at the physical manifestations of the chemical reaction. There is something called a transition zone in concrete. So far we have looked only at the cement paste, but in concrete you have sand and gravel, and many properties of concrete are controlled by the strength of the interfacial bond between the aggregate and the cement paste, and that interfacial bond is called the transition zone. The transition zone in portland cement concrete is very weak because of the presence of large crystals of calcium hydroxide which find space here due to the wall effect next to the coarse aggregate particles. You can see very clearly in the slide, these large calcium hydroxide crystals, they do not really bind with the aggregate, and they can be easily detached and cracked. And it is these cracks which are the ones that are responsible for the lack of impermeability, or lack of water tightness in concrete. So if you are able to build a stronger transition zone, then you can eliminate micro-cracking, and improve the impermeability, as well as improve the chemical durability, and thus end up with a highly durable concrete.
Also, the particles of coarse aggregate, due to the wall effect, tend to trap water next to the aggregate, and therefore what you see on the surface of the concrete as the visible bleed water is only part of the mixing water. A large amount of mixing water ends up as a locally high water-cement ratio type of cement paste next to the aggregate particles. When you vibrate concrete this is what happens: you have part of the extra mixing water on the surface as the visible bleed water, and a very large amount of bleed water due to internally trapped water next to the coarse aggregate.
The next slide shows you what happens (see figure 2.3). As a result of local high water cement ratio paste next to the coarse aggregate, you form the large crystals of calcium hydroxide, very large crystals, and you have large pores left over making this an area of weakness. If there is any stress, if there is any drying shrinkage, any thermal shrinkage, any loading and unloading effect, then these stress effects could very easily rupture the concrete. It would rupture next to the coarse aggregate particles because of the high porosity, and because this area is filled up with something which is not very strong, these are large plates of calcium hydroxide which can be cracked very easily.
The next slide shows you that this is what actually happens in the field. (see figure 2.4). From a thin section of concrete that deteriorated in a few years, you can trace the micro-cracks with a fluorescent dye. Sea water or de-icing chemicals can permeate very easily through these micro cracks, many of which are interconnected with the cracks which exist next to the aggregate particles. Most of the causes for lack of durability of reinforced concrete, whether it's alkali aggregate reaction, or the corrosion of steel, or sulfate attack, they can be very easily linked to the permeability of concrete, to its lack of water tightness. And this lack of water tightness is not there in freshly cured concrete; it comes later due to environmental effects: heating and cooling, wetting and drying, and because you have built in areas of weakness which micro-crack very easily. When these micro-cracks interconnect, you have channels of flow from outside, and that's how the aggressive chemicals get into the concrete.
------------------------------------------------------------------------
------------------------------------------------------------------------
Figure 2.3 Large calcium hydroxide crystals create a plane of weakness next to the coarse aggregate
Figure 2.4 Cross section of concrete showing interconnected micro-cracks adjacent to coarse aggregate.
CANMET Research
Next slide. There are two recent developments regarding high volume flyash concrete, one is the CANMET study which I mentioned earlier, and I want to show you some of the results using these mixes, and how they work. What happens to the voids in the transition zone if you increase the portland cement content of the concrete mixtures? The fine particles of cement in the internal bleed water would dissolve and you will still have voids although smaller in size. Now imagine what would happen if, instead of using the more reactive material (that is portland cement), you add fine particles of a less reactive material such as flyash and also reduce the water content of the concrete mix. You will end up with a less porous transition zone because these tiny glass beads of flyash will obstruct the channels of flow and will make the water-cement ratio more homogeneous in concrete by preventing the formation of local bleed water. And this is exactly what CANMET has found, by limiting the water content, and by introducing a large amount of flyash in the concrete mix. In this mix (see figure 2.5) there is 60% or 215 kg per cubic meter of flyash (360#/CY), 120 kg of mixing water (200#/CY), and 150 kg of cement (260#/CY). The water to cementitious ratio is limited to 0.32 due to the use of a super plasticizer, as well as due to air entrainment which is always required in Canada. So this is a typical CANMET mix, and the next slide shows the properties.
The bleeding with this mix ranges from very low to negligible due to the very low water content of this type of concrete, and also due to the obstruction of channels of flow, you don't expect bleeding on the surface. One of the negative side effects of this is, that you have to take proper care to prevent plastic shrinkage cracking. There are a lot of benefits to this material, but you will also have to learn about the negatives, what is the flip side of the coin. The flip side of the coin is you don't have the luxury of too much bleed water. The construction workers cannot take a coffee break and go away until the sheen is gone, and then come back and finish it. Because there is no sheen to go away, there is no bleed water at all, so you have to be aware of that.
Next slide. With the CANMET mix, the setting time is somewhat longer because remember, the cement content is less that 300 pounds here, and it is the cement that hydrates very, very quickly. It is the hydration of cement that forms calcium silicate hydrate, and as these fibers of calcium silicate hydrate grow, they tend to weave into each other and give you the time of set and strength. So if the cement content is low, naturally the time of set will be slow. But in general, the experience both from the laboratory and the field mixture is that high volume flyash concrete does not show unacceptable retardation in setting time, and demonstrates enough strength development to produce adequate strength at one day. They have obtained 10 MPa (1,500 psi) strength at one day in many of these mixes.
Next slide. Another very important advantage of flyash in concrete is the reduction of thermal cracking. Well known structural engineers who have been in the business for a long time, Professor T.Y. Lin, Professor Ben Gerwick, from their field experience can tell you that many of the problems in concrete are due to thermal cracking. Heat of hydration impacts are usually only considered in mass concrete, such as massive dams. But even in structures which are much less massive, only two or three feet thick, it is massive enough to accumulate enough heat of hydration to cause thermal cracking. So CANMET did a study on 10 foot x 10 foot x 10 foot cubes with a high volume flyash mix. Using this mix the temperature rise was only 35 degrees C compared to 65 degrees C in the control mix using only portland cement. This is a very significant advantage for the durability of concrete because thermal cracking would reduce the watertightness.
The typical compressive strengths that we get with this mix (see figure 2.6) is 8-10 MPa at one day, 35 MPa at 28 days, about 43 MPa at 91 days, and about 55 MPa at one year.
Next slide. Very important from the standpoint of sustainable development is the durability of structures. A lot of structural damage, especially in reinforced concrete, occurs due to the corrosion of steel. There is an ASTM test, rapid chloride penetration test ASTM C1202, where at 28 days 500 to 2,000 coulomb rating was found for the CANMET mixes (see figure 2.7). There is a table showing that anything less than 2,000 coulombs is a very low permeability concrete, so the permeability to CO2, and to chlorides which are responsible for the corrosion of steel is very low in the high volume flyash concrete. And this coulomb rating continues to improve, because many flyash particles react very slowly, pushing the coulomb value lower and lower.
A field test was undertaken by the University of Toronto. Preliminary data is shown in the next slide (courtesy of Professor Michael Thomas). In ten years you can see that the chloride penetration is negligible at about 1 inch depth of cover if you have 50% flyash in the concrete mix. It is an ongoing study in a tidal zone exposed to sea water, with 25 MPA concrete.
The next slide shows another advantage, this is based on a study by Professor Schiessl at the University of Aachen. In Europe they are very much concerned about dumping of industrial by-products because of the potential for ground water contamination. Flyash contains very small amounts of toxic elements, so they wanted to find out about the potential for the leaching of elements such as zinc, chromium, etc. Schiessl and his coworkers found out in the study that flyash concrete is very effective at immobilizing even externally added heavy metals in mortars. Test B is not a very good test, test C is the correct test for mortars and concrete, it is called the tank test and is a leach test on uncrushed specimens. They introduced into the mix, 185 mg of zinc per kg of mix. Then in the leach test they could only leach out 0.09 mg in 56 days. So it's not only that flyash concrete would prevent outside ions from getting in, but it also keeps whatever is in the concrete all tied up, it will not permit it to get out. If you have a toxic metal that has been immobilized by using flyash in concrete, rest assured that it will stay there. In the case of chromium from 53 mg of added chromium, only 0.15 mg could be leached out from the flyash mortar specimens.
Next slide. So this is the mix for the future. In the future, because of so many of these advantages, and much concern about sustainable development, we'll have not only portland cement in the concrete mix, we'll have silica fume and other pozzolans. And in this witches brew a super plasticizer, an air entraining admixture, or other chemical admixtures may be incorporated. This is the future.
Let me go back to a few more transparencies and then I'll finish. I mentioned the ASTM C1202 which is based on AASHTOis T277 test. A 1,000 to 2,000 coulombs current flow in a 6 hour test is a rating of low chloride permeability (see figure 2.8). This is usually a portland cement concrete with less than a 0.4 water cement ratio. If you want very low permeability, less than 1,000 coulomb rating, this is typical of an internally sealed pore system such as with a latex modified concrete. Such low permeability ratings can be obtained with ternary cement blends which I will discuss next.
Chloride Permeability Ratings per AASHTO T-277
Charge Passed
coulombs
Chloride Permeability
Typical of:
> 4000
High
Portland Cement Concrete
W/C > 0.6
2000 - 4000
Moderate
Portland Cement Concrete
0.4 < W/C < 0.6
1000 - 2000
Low
Portland Cement Concrete
W/C < 0.4
Thursday, July 8, 2010
advance cementitious material
Advanced cementitious materials
Dr.V.V.Deshmukh
Introduction :
Recent years have seen the development of many new advances in cementitious materials as ceramic like materials formed as the result of chemical reactions occurring at or near ambient temperatures. These new advances have occurred as a result of manipulating the microstructure and controlling the chemistry or both, of cements. These advances have led to the development of new families of high performance cementitious materials including very high strength materials. Some of these materials cross the boundaries of what has been defined as traditional cementitious materials, and the term chemically bonded ceramics has been used to classify these new materials. CBCs are defined at or near ambient temperatures. These new novel cements or CBCs follow the general rules of behavior of cementitious materials in certain respect The strength of hardened paste increases as the ratio of water to cement is reduced. Because the residual porosity, its distribution and the excess uncombined molecular water are responsible for most of the limitations on the properties of conventional hardened cement paste. Many attempts have been made to reduce the amount of water used in processing. The situation has changed beginning in about 1970 as new approaches have led to the development of more advanced cement matrix composites.
1) Densification by pressure and heat
The bonds limiting the strength of cement paste are normally thought to be weak van der waals forces Before 1970,the potential strength of cement paste at theoretical density had never been approached because considerable porosity (20 to 30% or more total porosity) always remain after complete hydration of cement. Following this research resulted in achieving very high strengths by warm pressing. Compressive strengths up to 650 Mpa (compared to more typical 30 Mpa) tensile strength up to 68 Mpa and values of youngs modulus up to 40 Gpa were attained. Enormous increases in strength resulted from the removal of most of the porosity and the generation of very homogenous fine microstructure with porosity's as low as 2%.
2) Micro defect free cement.
The warm pressed cements discussed in the previous section were successful but not easy to produce in large amounts due to the high pressure used. The next step was to develop more easily processed materials. .Another innovation was the engineering of a new class of high strength materials, the MDF cement. MDF refers to the absence of relatively large voids or defects which are usually present in conventionally mixed cement paste because of entrapped air and inadequate dispersion. In the MDF process 4 to 7% of one of several water soluble polymer is added as a rheological aid to permit cement to be mixed with very small amount of water., subsequent high shear mixing produces a plastic cohesive mixture which can be shaped by extrusion or other forming technique and which sets in times ranging from minutes to hours. The highest strength materials have been prepared with calcium aluminate cement. Control of the particle size distribution for optimum particle packing was also considered important for generating strength. A final processing stage in which entrapped air is removed by applying modest pressure or heating at 80 0C resulted in a paste that is free of large defects. with excellent mechanical properties. Very low porosity's were achieved <1% as well as flexural strength of 150 Mpa. compressive strength of 300 Mpa and a young’s modulus of 50 Gpa. When MDF material is exposed to moisture, the polymer phase which MDF cement where constitute 30% on a volume basis, swells and softens. This property of MDF cement has restricted the use of its in application where water is used.
3) DSP and other densely packed systems
An important class of new materials termed DSP (Densified systems containing homogeneously arranged ultrafine particles) was first elucidated in detail by Bache The new class of materials is defined as materials with matrix comprising of 1) Densely packed particles of a size ranging from 0.5 to 100micron usually cement 2) Homogeneously arranged ultra-fine particles ranging in size from 50 A0 to 0.5 microns usually silica fume, arranged in the spaces between the larger particles. The combination of densely packed silicafume and cement was found to benefit for a combination of reasons
1) The silica particles are smaller than even the finest cement produced by grinding and therefore pack more easily into the spaces between the cement particles.
2) The silica particles are spherical in shape
3) The particles are chemically less reactive than cement, which eliminates the problem of too rapid hardening encountered with very fine cement
4) Finally with added dispersing agents a low water requirement may be achieved.
Numerous investigations have contributed to the understanding of the effects of fine particles in densely packed cementitious materials. With 15% silica fume replacement of cement thwere are 2000000 particles of silica fume for each grain of portland cement in a concrete mixture. Concrete containing 5 to 15% silica fume have high compressive strengths up to 100 Mpa flexural strength up to 12 Mpa and young’s moduli (up to 34 Gpa)and have very low permeability to water (10-9 um).The microstructure of the critical interfacial zone between cement paste and the aggregates in concrete is more dense and uniform than when conventional pastes are used and the bond between paste and other embedded materials such as aggregates and fibers appears to be improved. The most striking results have been found with silica fume substituted pastes and DSP systems. Compressive strengths of up to 270 Mpa or higher with young’s moduli up to 80 Gpa were achieved in preparations with up to 20 to 25% silicafume at a water to solid ratio of 0.12 to 0.22 through mechanical compaction. Such materials are used to resist mechanical erosion in impeller screws for moving coal and fly ash and in flooring to industrial area. This material retains a compressive strengths of 300 Mpa up to about 500 0c and 200 Mpa at about 700 0C.
Silica fume hydration reactions.
Properly dispersed silica fume particles when used in propertions to replace up to 10 % of cement significantly reduces the bleeding and segregation of the mixtures and may be used in higher proportions. Silica fume contains particles as fine as 0.1 microns or less which partially dissolve in saturated Ca(OH)2 solution in a time as early as 5 to 15 minutes, and a SiO2 rich hydrates is deposited in layers or films on the silica fume particles. Despite the early rapid reaction much silica fume is remained for later slow reaction. The fume particles play an important role in various composites when they surround each cement grain, densifying the matrix, filling the voids with the strong hydration products and improve the bonding with aggregates, and reinforcing materials such as fibers. Silica fume by reacting with alkali also affords a protection against the alkali aggregate type reaction occurring between a cement pore solution and glass fiber.
Particle packing in concrete.
The Toufar/Aim model of dry particle has been verified as adequately modeling the dry packing of mixers of powder, each with a different size distribution. Typically in the model ,materials with three different size distributions may be mixed .Furthermore, the characterization of the size distribution can be modeled by a commonly used procedure describe by Rosin-Rammler. Input to this PC-based algorithm consists of the experimentally determined tap density of each component and the characteristic diameter of the distribution as described by D in Rosin-Rammler fitting equation. The results of applying this algorithm to concrete systems have provided the mathematical basis for formulating concrete mixtures which were developed through field experience in the concrete placement. Its applications should prove useful in monitoring the quality of concrete in the design stages and to maximize performance.
Discussion and summary
The particle packing and hydration reactions in DSP cement pastes are responsible for the fine microstructural development. These complex reactions involve phase solubility ,accelerating and retarding effects of a multiphase, multiparticle size distribution material, and surface effects at the solid-liquid interface. This particle packing combined with chemical reaction is extremely important for developing strength. The initial degree of dispersion of cement and fume in the paste strongly influences the development of the final hardened paste microstructure. The ultra fine particles can fill the intergranular interstices and produce a dense paste structure. Reflected in a high strength. Superplasticizers should be used to minimize the water demand and adequately disperse the fine particles, resulting in dense products with fine pore size, very low permeability and low ionic diffusivity. Despite the rapid early hydration, much silica fume remains unreacted until a later stage. Physical and chemical characteristics together influence the hydration kinetics. Silica fume ordinaraly accelerates the early portland cement hydrtion, largely because of its very high surface area, increasing the heat development and resembling a high early strength cement. Fume also disperses the hydration product, provides for deposition of C-S-H and there by fills the pore interstices with fine hydration products. The mechanical properties of some highstrength DRC -type materials have been summarised in table given below
Dr.V.V.Deshmukh
Introduction :
Recent years have seen the development of many new advances in cementitious materials as ceramic like materials formed as the result of chemical reactions occurring at or near ambient temperatures. These new advances have occurred as a result of manipulating the microstructure and controlling the chemistry or both, of cements. These advances have led to the development of new families of high performance cementitious materials including very high strength materials. Some of these materials cross the boundaries of what has been defined as traditional cementitious materials, and the term chemically bonded ceramics has been used to classify these new materials. CBCs are defined at or near ambient temperatures. These new novel cements or CBCs follow the general rules of behavior of cementitious materials in certain respect The strength of hardened paste increases as the ratio of water to cement is reduced. Because the residual porosity, its distribution and the excess uncombined molecular water are responsible for most of the limitations on the properties of conventional hardened cement paste. Many attempts have been made to reduce the amount of water used in processing. The situation has changed beginning in about 1970 as new approaches have led to the development of more advanced cement matrix composites.
1) Densification by pressure and heat
The bonds limiting the strength of cement paste are normally thought to be weak van der waals forces Before 1970,the potential strength of cement paste at theoretical density had never been approached because considerable porosity (20 to 30% or more total porosity) always remain after complete hydration of cement. Following this research resulted in achieving very high strengths by warm pressing. Compressive strengths up to 650 Mpa (compared to more typical 30 Mpa) tensile strength up to 68 Mpa and values of youngs modulus up to 40 Gpa were attained. Enormous increases in strength resulted from the removal of most of the porosity and the generation of very homogenous fine microstructure with porosity's as low as 2%.
2) Micro defect free cement.
The warm pressed cements discussed in the previous section were successful but not easy to produce in large amounts due to the high pressure used. The next step was to develop more easily processed materials. .Another innovation was the engineering of a new class of high strength materials, the MDF cement. MDF refers to the absence of relatively large voids or defects which are usually present in conventionally mixed cement paste because of entrapped air and inadequate dispersion. In the MDF process 4 to 7% of one of several water soluble polymer is added as a rheological aid to permit cement to be mixed with very small amount of water., subsequent high shear mixing produces a plastic cohesive mixture which can be shaped by extrusion or other forming technique and which sets in times ranging from minutes to hours. The highest strength materials have been prepared with calcium aluminate cement. Control of the particle size distribution for optimum particle packing was also considered important for generating strength. A final processing stage in which entrapped air is removed by applying modest pressure or heating at 80 0C resulted in a paste that is free of large defects. with excellent mechanical properties. Very low porosity's were achieved <1% as well as flexural strength of 150 Mpa. compressive strength of 300 Mpa and a young’s modulus of 50 Gpa. When MDF material is exposed to moisture, the polymer phase which MDF cement where constitute 30% on a volume basis, swells and softens. This property of MDF cement has restricted the use of its in application where water is used.
3) DSP and other densely packed systems
An important class of new materials termed DSP (Densified systems containing homogeneously arranged ultrafine particles) was first elucidated in detail by Bache The new class of materials is defined as materials with matrix comprising of 1) Densely packed particles of a size ranging from 0.5 to 100micron usually cement 2) Homogeneously arranged ultra-fine particles ranging in size from 50 A0 to 0.5 microns usually silica fume, arranged in the spaces between the larger particles. The combination of densely packed silicafume and cement was found to benefit for a combination of reasons
1) The silica particles are smaller than even the finest cement produced by grinding and therefore pack more easily into the spaces between the cement particles.
2) The silica particles are spherical in shape
3) The particles are chemically less reactive than cement, which eliminates the problem of too rapid hardening encountered with very fine cement
4) Finally with added dispersing agents a low water requirement may be achieved.
Numerous investigations have contributed to the understanding of the effects of fine particles in densely packed cementitious materials. With 15% silica fume replacement of cement thwere are 2000000 particles of silica fume for each grain of portland cement in a concrete mixture. Concrete containing 5 to 15% silica fume have high compressive strengths up to 100 Mpa flexural strength up to 12 Mpa and young’s moduli (up to 34 Gpa)and have very low permeability to water (10-9 um).The microstructure of the critical interfacial zone between cement paste and the aggregates in concrete is more dense and uniform than when conventional pastes are used and the bond between paste and other embedded materials such as aggregates and fibers appears to be improved. The most striking results have been found with silica fume substituted pastes and DSP systems. Compressive strengths of up to 270 Mpa or higher with young’s moduli up to 80 Gpa were achieved in preparations with up to 20 to 25% silicafume at a water to solid ratio of 0.12 to 0.22 through mechanical compaction. Such materials are used to resist mechanical erosion in impeller screws for moving coal and fly ash and in flooring to industrial area. This material retains a compressive strengths of 300 Mpa up to about 500 0c and 200 Mpa at about 700 0C.
Silica fume hydration reactions.
Properly dispersed silica fume particles when used in propertions to replace up to 10 % of cement significantly reduces the bleeding and segregation of the mixtures and may be used in higher proportions. Silica fume contains particles as fine as 0.1 microns or less which partially dissolve in saturated Ca(OH)2 solution in a time as early as 5 to 15 minutes, and a SiO2 rich hydrates is deposited in layers or films on the silica fume particles. Despite the early rapid reaction much silica fume is remained for later slow reaction. The fume particles play an important role in various composites when they surround each cement grain, densifying the matrix, filling the voids with the strong hydration products and improve the bonding with aggregates, and reinforcing materials such as fibers. Silica fume by reacting with alkali also affords a protection against the alkali aggregate type reaction occurring between a cement pore solution and glass fiber.
Particle packing in concrete.
The Toufar/Aim model of dry particle has been verified as adequately modeling the dry packing of mixers of powder, each with a different size distribution. Typically in the model ,materials with three different size distributions may be mixed .Furthermore, the characterization of the size distribution can be modeled by a commonly used procedure describe by Rosin-Rammler. Input to this PC-based algorithm consists of the experimentally determined tap density of each component and the characteristic diameter of the distribution as described by D in Rosin-Rammler fitting equation. The results of applying this algorithm to concrete systems have provided the mathematical basis for formulating concrete mixtures which were developed through field experience in the concrete placement. Its applications should prove useful in monitoring the quality of concrete in the design stages and to maximize performance.
Discussion and summary
The particle packing and hydration reactions in DSP cement pastes are responsible for the fine microstructural development. These complex reactions involve phase solubility ,accelerating and retarding effects of a multiphase, multiparticle size distribution material, and surface effects at the solid-liquid interface. This particle packing combined with chemical reaction is extremely important for developing strength. The initial degree of dispersion of cement and fume in the paste strongly influences the development of the final hardened paste microstructure. The ultra fine particles can fill the intergranular interstices and produce a dense paste structure. Reflected in a high strength. Superplasticizers should be used to minimize the water demand and adequately disperse the fine particles, resulting in dense products with fine pore size, very low permeability and low ionic diffusivity. Despite the rapid early hydration, much silica fume remains unreacted until a later stage. Physical and chemical characteristics together influence the hydration kinetics. Silica fume ordinaraly accelerates the early portland cement hydrtion, largely because of its very high surface area, increasing the heat development and resembling a high early strength cement. Fume also disperses the hydration product, provides for deposition of C-S-H and there by fills the pore interstices with fine hydration products. The mechanical properties of some highstrength DRC -type materials have been summarised in table given below
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