WHAT
WAS NOT POSSIBLE YESTERDAY IS POSSIBLE TODAY
Dr Vilas Deshmukh (M.Sc, .PhD) Material Scientist, ACC Limited Consultant
ACC Concrete, India- 400607
Abstract
Millions of rupees are spent on
rehabilitation of roads in India. There is a pressure from people on municipalities
for pothole free roads. The author in this paper in detail studied ultra thin
white topping and grouted macadam as two alternate technologies for cheaper and
long lasting roads
The author has first time used Grouted Macadam (GM) for the
rehabilitation of damaged Bituminous Roads in Mumbai Municipal Corporation(BMC)
in the year 2000. In the year 2003 the same technology grouted macadam was used
in Surat Municipal Corporation. The year 2000, the acceptance of the GM
technology was bit early but today it has an edge over the conventional Bituminous
Macadam (BM) .This is because bitumen cost has shoot up many fold in last two
years.
The author has also first time used TWT(Thin White Topping) and UTWT(Ultra
thin white topping) for the repairs of damaged bituminous roads in Thane Municipal
Corporation. The technology is so popular that about 25km roads have been laid.
The technology became popular that DD SAHYADRI TV channel has telecast the
programme on UTWT (ultra thin white topping). It is an opportunity to all
concern for infrastructure in this country to immediately adopt these technologies.
Keywords: Ultra thin white topping, UTWT, Thin white topping, TWT, Rural
roads, Village roads, Grouted macadam,
Introduction
Rural roads mostly made of bituminous macadam are in bad shape because of severe climatic
conditions and non availability of funds for maintenance . The concrete roads
are recommended because of no severe climatic condition affect the performance
of concrete roads.
The main constrain is the cost .There is general perception of the
construction fraternity the concrete roads are costly. The old pundits of the
pavement industry are familiar with asphalt pavement because last five decades
the asphalt roads are made over concrete. People are not aware of significant
development in concrete admixture and its effect on strength and performance.
It is possible to produce concrete at much cheaper cost.
India
with growing industrialisation needs good quality roads. All over the world two
types of roads are built asphaltic and concrete. Asphaltic roads are popular
all over the world because of the economic consideration and fast laying
procedure. Even in our country also asphaltic roads are very much popular but
asphaltic roads in our country do not last .besides there is no maintenance of
the roads due to lack of funds ,which is a common feature in India.
Millions
of rupees are required for resurfacing of the roads. In Mumbai city alone millions
of rupees are wasted on fuel loss and hours of
time loss due to bad roads. It takes four to six hours to reach Santa Cruz air
port from Thane, a distance of thirty kilometres
I)Indian
road
In
India almost 80%of passenger traffic and about 65% of freight movement is
handled by the road networks. In
general, roads in India are primarily bitumen based macadamised roads However a
few of the national highways have concrete roads. In some location such as in
Kanpur, the British built concrete roads are still in use. The concrete roads
are less popular prior to 1990s because of less availability of cement then.
However over the years with large supply of cement in the country and the
virtues of concrete roads, they are once again gaining popularity. Concrete
roads are weather proof and required lower maintenance than compared to
bituminous roads. Because bitumen is obtained from imported crude oil and due
to other factors concrete based roads proved to be most cost effective in the
long run in future.
There is
a situation where funds are limited and the existing bituminous roads do not
last. There is also pressure of fellow citizens on the need for good roads due
to increasing population, and increasing vehicular traffic.
The
Associated Cement Companies, a leading cement and concrete producing company
extensively studied technologies namely grouted macadam and ultra thin white
topping which is a solution to the above mentioned problems of roads and their
technologies. The author started working in the year 1998 and has used the
multidisciplinary approach to study the above mentioned technologies The
technologies grouted macadam and ultra thin white topping were developed
strictly keeping in mind the total cost of the implementation and were ready to
use which was a solution in an integrated approach catering to a varied
requirements of road making and its maintenance.
Ultra thin white topping & Grouted macadam technologies
|
Instant Pothole filling material
|
Airport runways, port roads
|
Intersection of roads / junctions
|
Bridge decks, internal society
roads and streets
|
Fig 1: Application of the technologies
As per the authors survey of rural
roads out of 33lack km of length only 2lakh kilometre carry heavy traffic from
30MSA(Million standard axle) to 200 MSA and only about 50000 kilometre may be carrying more than 100
MSA. Majority of village roads and ODR(other district roads) of about 28 lack
kilometre must be carrying traffic less then 3MSA.Considering the present road construction activity the same
will need 175 cubic meter of aggregate every year which is creating
environmental issue .Large requiring of sand also creating problem of
underground water. Heavy consumption of diesel and bitumen is increasing our
burden of foreign exchange .Most of the village roads are seriously affected
due to inadequate provision of maintenance grand.
About 90% length is metalled and top
WBM(wet bound macadam) layer is seriously affected and not in traffic worthy
condition .The black topped village roads are also heavily damaged due to lack
of renewal cost. Huge funding is required to revive these assets to proper standards
.we therefore plan such specifications and develop technology which can result
into more durable assets at minimum affordable cost. All low volume roads are usually
provided with thin bituminous surfacing which require constant maintenance of
potholes formed during rains. The roa also require major renewals such as
bituminous carpet and seal coat after every five years. if there is water
logging due to lack of drainage the bituminous surface may get damp within a
week of construction and entire investment is lost in a short time There is
need for suitable pavement material having expected life of 15 to 20 years
which is low in initial and maintenance cost not affected by water labour
intensive and employment generation and dust free environment.
In such situation
author has optimised the following technologies
1) White topping
2) Grouted macadam
II)White topping
technology : This technology is used for badly damaged metalled
road. Damaged blacktopped roads in
urban area are made traffic worthy condition by laying a concrete overlay
called “Thin White topping”(TWT) of M 40 grade concrete having thickness of
80mm to 150mm, depending on traffic intensity and assessing the strength of existing roads. Joints are cut at
800mm to 1000 mm in both direction and thus behaviour gets changed to large
paver size block wherein the lower strata is capable of taking the load. It is
proposed to adopt same principles to convert the existing damaged metalled
road.
2.1 )Historical development in urban pavement
technology at Thane Municipal Corporation(TMC)
The author in the year 2007 approached
city engineer Mr.K.D.Lalla and laid
first trail patch of UTWT(Ultra thin
white topping) in Thane city. The condition of the road is
without any pothole even after six years. The response was so positive that TMC incorporated UTWT in
their tender specification.
2.2)
Mix design for white topping as overlay for TMC
|
Material
|
Kg/M3
|
Rs/Kg
|
Cost
|
Density
|
Volume
|
|
cement
|
360
|
5.5
|
1980
|
3.15
|
114.29
|
|
flyash
|
150
|
1.8
|
270
|
2.25
|
66.67
|
|
micro silica
|
0
|
22
|
0
|
|
|
|
sand
|
917
|
0.6
|
550.2
|
2.69
|
340.89
|
|
metal-2
|
450
|
0.6
|
270
|
2.88
|
156.25
|
|
metal-1
|
550
|
0.6
|
330
|
2.88
|
190.97
|
|
admix
|
3
|
107
|
321
|
1.23
|
2.44
|
|
water
|
160
|
0.4
|
64
|
1
|
160.00
|
|
fibre
|
0
|
225
|
0
|
|
1031.51
|
|
2590
|
|
3785.2
|
|
|
|
COMPRESSIVE STRENGTH
|
7-DAYS
|
25mpa
|
|
|
28-days
|
40mpa
|
|
Powder content(kg)
|
510.00
|
|
|
|
water/powder
|
0.88
|
88
|
|
|
past content
|
0.33
|
36
|
|
|
sand content
|
0.33048015
|
35
|
|
|
coarse aggregate
|
0.33661683
|
28
|
|
|
|
|
|
Table 1: Mix Design
for Cityl Roads
2.3) Methodology The following methodology was adopted
for laying the TWT.
1) Milling 2) Sub-base preparation
3) Concreting 4) Curing
2.3.1)
Milling & Sub Base preparation: Milling is essential on old bituminous
roads to create rough surface for bonding the old bituminous surface with the
concrete overlay. Milling also
establishes the finished grade line. In addition, camber correction can be
achieved as required. A writgen milling
machine was used to mill the top few mm of the bituminous surface. The material removed from milling was used
for land filling. Engineers took precaution
to remove any loose material from the milled surface by brooming before placing
the concrete.
2.3.2) Sub Base preparation
Before placing concrete, bituminous surface was
wetted so that it does not absorb water from the concrete mix. Owing to its dark colour, the bituminous
surfaces store heat from the sunlight.
Watering helps bring down the surface temperature. Accordingly, water
was sprayed using a hose connected to a water tanker. However, care was taken to ensure that no
excess water remained on the surface. Stretches of roads showing sub grade
failure or settlement of pavement would not provide uniform support to the overlay. It was therefore necessary to remove and
replace sub-grade from such areas.
The sub-base preparation was an important step
of overlay process at Thane because often roads are dug up for laying electric
cables, sewerage pipelines, water pipelines, telephone cables and fiber optic
cables. The providers of these utility
services do not make good the dug up portions properly. Often the utility trench is covered without
adequate compaction and in such situations the overlay is bound to fail. Engineers took special precautions by
removing loose material from such trenches.
In filling them with 40 mm stone with proper compaction and covering
them with a 150 mm thick Dry Lean Concrete layer.
Fig 2: Milling
machine in operation
Fig 3: Layer of BM as sub base preparation
2.3.3).Treating
sewer chambers:-The surface around
manholes or chambers meant for accessing underground sewer pipelines are
vulnerable spots for overlay failure.
The existing chambers were raised to the road level. Engineers took precautions to strengthen the
area around manholes or chambers by reinforcing the concrete with a metal mesh
of 6-8 mm diameter steel wires. Engineers made provisions for placing utility
lines across the road by laying 200 mm diameter concrete pipes across roads
wherever needed. They improved surface
drainage by providing side drains whenever required.
2.3.4) Concreting
With the advent
ready mixed concrete industry in and around Thane, the many advantages
associated with ready mixed concrete were considered useful for UTWT projects.
They are
·
Accuracy of mix
concrete and calibration of the components.
·
Accuracy of
controlling the quality of the cement, aggregates, water and additives.
·
Superiority of the
mixing process quality due to absence of human error.
·
Accuracy and
centralized monitoring of quality control operation.
·
Avoidance of the
burden of storing raw materials at site during the production of concrete.
·
Reduction and time
saving of site work duration.
·
Consistent quality.
Engineers made the
use of ready mixed concrete compulsory in TWT projects, encouraged by these
advantages. The concrete of 3 day compressive strength of 40 MPa and flexural
strength of 4.5 MPa was used for overlay.
2.3.5) Curing
Immediately after
concreting, the initial curing was carried out by water spraying. Curing was
continued by resorting to ponding for seven days.
2.3.6) Joint cutting
The cutting of
joints is an important step for ensuring design performance from the TWT. The
overlay was cut within eight to ten hours after placing the concrete. The short joints of 1 meter by 1 meter were
cut to avoid cracking. The hot bitumen
was used as a sealant.
Using the above mix design, methodology and the
integrated approach of road development with proper drains, manholes and
shoulders, TMC engineers have successfully carried TWT projects on several
stretched of roads in Thane city. Figures 4 & 5 shows some of the roads
finished with TWT.
Fig 4: Laying of white topping in progress Fig5: Typical Thin White topping road
In SCC the mix is governed by the above mentioned parameters namely
powder content, water/powder ratio, pest content, sand content and coarse
aggregate.
.
III)Historical development in rural
pavement technology at Murbad Thane
The Thane unit of PMGSY made history by adopting
/experimenting technology which is different than regular prescribed method of
Road building In the month of April 2011 thane unit of PMGSY was successful in laying 150 mm of PQC on
150mm of GSB(Granulated Sub Base) The concrete used was totally different than
conventional concrete.
The M-40 Grade concrete is made
by using 290kg of cement. The reduction in cement quantity was possible by
using additives like flyash, silica fume, GGBS etc. and by
using water reducing admixture like BASF Glenium sky, Glenium 276 etc.
The SCC(Self Compacted Concrete)
technology is used to achieve concrete to spread of its own weight.First time
the joint cutting is avoided by placing geo-polymer strips of 50mm in 150mm
concrete at regular interval.
Three fundamental changes in
concrete technology made it possible to give concrete roads to villages at slightly
higher cost. The white topping has made distinct difference in the output.
1.
Maintenance free roads for next fifteen
years
2.
Acceleration of rural economy.
3.
Saving in raw material namely lime stone by less use of cement.
Few
photographs of the concrete road at Kundebangar Wadi under the scheme of Prime
Minister of Gram Sadak Yogna (PMGSY) in a sequence in Fig 6.
Mix design for PMGSY:
SCC concrete
|
MATERIAL
|
kg/M3
|
RS/KG
|
COST
|
DENSITY
|
VOLUME
|
|
cement
|
290
|
5.40
|
1566
|
3.1
|
93.55
|
|
flyash
|
200
|
1.8
|
360
|
2.25
|
88.89
|
|
sand
|
355
|
0.6
|
213
|
2.69
|
131.97
|
|
crush stone
|
355
|
0.75
|
266.25
|
2.88
|
123.26
|
|
metal-2
|
536
|
0.6
|
321.6
|
2.88
|
186.11
|
|
metal-1
|
630
|
0.6
|
378
|
2.88
|
218.75
|
|
admix-BASF-B-276
|
3
|
107
|
321
|
1.23
|
2.44
|
|
water
|
150
|
0.4
|
60
|
1
|
150.00
|
|
|
|
|
|
994.97
|
|
2519
|
|
3485.85
|
|
|
|
slump flow
|
400mm
|
|
|
ycone
|
8sec
|
|
|
water/cementitious
|
0.306122
|
|
|
|
|
|
|
|
|
|
Gradation for crush stone and sand
|
%PASSING
|
|
10MM
|
100
|
|
4.75MM
|
90-100
|
|
2.36MM
|
60-95
|
|
1.18MM
|
30-70
|
|
600MICRON
|
15-34
|
|
300MICRON
|
5_20
|
|
150MICRON
|
0-10
|
|
Gradation for metal i&ii
|
metal ii
|
metal i
|
|
%passing
|
|
|
20mm
|
95-100
|
100
|
|
16mm
|
|
|
|
12.5mm
|
|
90-100
|
|
10mm
|
25-55
|
40-85
|
|
4.75mm
|
0-10
|
0-10
|
Table 2: Mix Design for Rural Road
Flyash should be from field 3 residue on 45 micron is 10%
A trail stretch of about 900m with above technology has been done for a
project near Kalyan Feasibility and cost advantage has been proved beyond
doubt.
IV)Historical work carried out in Bhangarwadi village near Kalyan is
given below
Fig 6: Six photos ( from left to right in two rows) indicating the sequence of laying the rural
road-Mixer for making concrete, Laying of channel, Transport of Concrete, Placing
of concrete, Finished road, and Ready to use road open on third day.
Recently further reduction in concrete
cost is possible by using reactive flyash from TATA thermal power plant. The
flyash is different from other Indian flyash .because the TATA power uses Indonesian
coal for firing. The chemical composition of Indian and Indonesian flyash is
given below
|
Element
|
INDONESIAN
COAL
|
INDIAN COAL
|
|
·
SiO2
|
·
33.9
|
·
57.5
|
|
·
Al2O3
|
·
20.4
|
·
29.8
|
|
·
Fe2O3
|
·
19.8
|
·
5.8
|
|
·
CaO
|
·
14.9
|
·
0.4
|
|
·
MgO
|
·
5.8
|
·
1.0
|
|
·
Na2O
|
·
0.54
|
·
0.07
|
|
·
K2O
|
·
0.93
|
·
1.55
|
|
·
TiO2
|
·
0.70
|
·
1.3
|
|
·
SO3
|
·
0.8
|
·
0.08
|
|
·
Carbon
|
·
1.6
|
·
2.2
|
|
·
LOI
|
·
2.2
|
·
2.4
|
|
·
IR
|
·
40.8
|
·
92.9
|
Table 3: Chemical composition of Indian
and Indonesian Flyash
Chemical analysis of typical Indian coal flyash and Tata
power Indonesian coal flyash is given in table 3
V)Benefits of using TATA POWER
Flyash
·
More
replacement of cement by flyash
·
The
early day strength is not reduced
·
Production
of green concrete.
The strength data of various
compositions is studied and the results are given below:
|
cost/RS
|
3-DAYS
|
7DAY
|
28DAYS
|
56DAYS
|
w/b
|
exp.conducted
|
|
original mix
|
2665.8
|
16.96
|
20.47
|
37.63
|
46.91
|
0.38
|
BASF
|
|
260+100pfa
|
2546.75
|
12.99
|
18.79
|
29.96
|
42.28
|
0.38
|
BASF
|
|
250opc+100pfa
|
2511.65
|
13.28
|
17.81
|
32.38
|
38.78
|
0.38
|
BASF
|
|
250opc+90pfa
|
2519.2
|
12.9
|
38.19
|
33.06
|
36.97
|
0.38
|
BASF
|
|
240opc+90pfa
|
2501.1
|
12.77
|
18.76
|
38.19
|
39.01
|
0.38
|
BASF
|
|
240opc+100pfa+20alcofine
|
2809.75
|
12.79
|
20.3
|
33.63
|
43.01
|
0.38
|
BASF
|
|
230opc+100pfa+20alcofine
|
2711.65
|
11.24
|
16
|
29.26
|
41.44
|
0.38
|
BASF
|
|
210opc+90pfa+30alcofine
|
2842.2
|
14
|
19.53
|
35.18
|
39.13
|
0.38
|
BASF
|
|
290opc+200pfa
|
2445
|
18
|
25
|
38
|
|
0.34
|
Pune Engineering
College
|
|
290opc+200pfa from tata power
|
3265
|
25
|
35
|
51
|
|
0.35
|
BASF
|
Table
4: Strength data of various compositions and their results
Fig 7: Tata
flyash effectiveness on Compressive strength
For village roads normally crust
consist of 300mm sub grade ,200mm GSB(Granulated sub base),150-to 225 mm WMM(Wet mix macadam) 20MM carpet and seal coat. Carpet and seal
coat does not add to strength but act as dust proof course. It also prevents
the sucking of blindage from WMM due to pneumatic tyre and thereby prevents the
damage to WMM/WBM surface. Most of the village roads are metal led and for the
want of maintenance grand top later is worn out. Almost top 75mm to 100mm WBM/WMM Layer is heavily
damaged in such cases normally additional 75mm to 100mm WBM/WMM layer is added and road is
restored to proper camber.20mm carpet and seal coat is added as wearing course
As an alternate to above
the levelling course itself could be converted into impervious top layer of
grouted macadam.
VI)Grouted Macadam Technology
The composite
material comprises of porous asphalt skeleton into which cementitious grout is
poured completely filling the voids. This type of pavement has the potential to
combine the best qualities of flexible and rigid pavement. The best qualities are due to absence of joints because
of asphalt and long life due to high bearing capacity of concrete. The impervious surface of grouted macadam mixture provides good
protection to the foundation against the ingress of water.
Grouted Macadam consists of polymer coated aggregates with 25-30% voids
in which is poured a cementitious grout.
The grout is of improved cementitious binder which allows greater
penetration of the void structure of polymer coated aggregate (PCA) and hence
greater achievement of the theoretical packing density. The resulting material
is typically used as a wearing course between 25mm and 75mm in thickness.
This type of grouted material offers the
following benefits over a conventional bituminous material.
·
High resistant to permanent deformation
·
Fuel spill resistance
·
Lower temperature susceptibility
·
Higher Stiffness modulus.
Grouted Macadam consists of an open graded coated
aggregates with voids completely filled up with a special cement based grout.
The grout is a dry, ready mixed which, when mixed with water, is a very light
fluid material with high properties of penetration and internal cohesion.
Grouted Macadam is laid
jointless. The special coated aggregates provide the flexibility and the grout,
with its characteristic dense micro structure, high wear resistance and high
durability in aggressive environments.
Fig
7: sequence of laying Grouted macadam –laying bituminous macadam, pouring of
grout, scraping of grout to finish the road.
Details of the jobs conducted
at BMC(Mumbai municipal corporation) and
SMC(surat municipal corporation) are listed as 9 jobs at places from Lonavala
to Navi Mumbai, 20 jobs in Greater Mumbai, and outside Mumbai namely Surat,
Tikariya and Kymore. . The technology used is grouted macadam developed by the
author in ACC-RCD.
6.1
The CRRI(central road research institute)Report
Fig 8: Sion circle made pothole free evaluated by CRRI
The product properties are
studied by CRRI. The report is given below:
Laboratory Testing Of Grouted Macadam by CRRI
: The
performance evaluation of Grouted Macadam overlaid road sections was certified
by the Central Road Research Institute
(CRRI), New Delhi.. The team of CRRI scientist visited the Grouted Macadam
site in Mumbai on Aug.2002.. The periodic observations included are the
evaluated performance for skid resistance measurements using British Portable
Skid Resistance Tester, surface texture depth measurements and extraction of
pavement cores for determination of abrasion resistance, effect of water,
petroleum products and temperature on Grouted Macadam.
6.2)The skid resistant measurements Skid resistance
measurements were under taken on the representative locations under dry and wet
conditions of the pavement. Skid resistance values as obtained have been given
in Table 5
|
Location
|
Skid
Resistance Values
|
Minimum
Skid Resistance Requirements
|
Remarks
|
|
Dry
condition
|
Wet
condition
|
|
*Average
|
Range
|
*Average
|
Range
|
|
Inner lane
|
92
|
85 - 97
|
53
|
52 - 57
|
55
|
Good surface condition with coarse surface texture
|
|
Central lane
|
92
|
86 - 96
|
59
|
55 - 64
|
55
|
Good surface condition with medium to
coarse surface texture
|
|
Outer lane
|
91
|
87 - 95
|
55
|
55 - 56
|
55
|
Good surface condition with medium to
coarse surface texture
|
*Average based on ten observations. Table 5 : Skid resistance values
6.3) Texture depth measurements.
Texture depth
measurements were also made at representative locations where skid resistance
was measured. The standard sand of known density was used .A known volume of
fine sand of uniform particle size is poured on the road surface and the sand
is spread until all the cavities are filled. The mean texture depth of the
surface is calculated and the results are given in Table 6.
|
Lane
|
Mean
Texture Depth (mm)
|
Surface
Texture Classification
|
Remarks
|
|
Range
|
Average
|
Coarse
texture
|
Medium
Texture
|
Fine
Texture
|
|
Inner lane
|
0.37- 0.77
|
0.57
|
³0.50mm
|
0.50-.25mm
|
< 0.25 mm
|
Good surface condition with medium to
coarse surface texture
|
|
Central lane
|
0.80- 1.50
|
1.15
|
³0.50 mm
|
0.50-.25mm
|
< 0.25 mm
|
Good surface condition with coarse surface texture
|
|
Outer lane
|
0.60- 0.92
|
0.74
|
³0.50 mm
|
0.50-.26mm
|
< 0.25 mm
|
Good surface condition with coarse surface texture
|
Table 6: Mean texture depth of the surface
6.4) Traffic volume counts :
The daily
traffic flow was assessed based on 24 hours volume count. Cars, buses, trucks,
light goods and other commercial vehicles were recorded during the survey.
Shown in Table 8
|
Vehicle Type
|
Cars ( C )
|
Buses ( B )
|
Trucks ( T )
|
*Other Goods
Vehicles
|
|
Number of
vehicles
|
50329
|
9566
|
6271
|
5939
|
Table 7: 24
Hours Traffic Volume Count at Sion Circle
* Includes
Tractors/Tractor trolleys etc.
6.5) Abrasion resistant :
The
cylindrical cores of 100mm diameter and 20-50 mm height were cut from
representative locations. Core cutting was done using electrically operated (220v,1.8KW
)BOSCH portable core cutting machine. These core samples were tested for
abrasion as per IS 9284-1979.The abrasion test results of Grouted Macadam
sample are given in table-8.
|
Sr. No.
|
Sample No.
|
Percent loss
in weight
|
Tentative Suggested Maximum
Value of Abrasion 5Loss (%)
|
|
1
|
11
|
0.25
|
(I) concrete pavement
|
|
|
2
|
13
|
0.21
|
(a)With mixed traffic
including iron tyred traffic
|
= 0.16
|
|
3
|
14
|
0.21
|
( b) With
pneumatic
tyred traffic
|
= 0.24
|
|
4
|
15
|
0.29
|
(ii) Factory
floors
|
= 0.16
|
|
Average
|
|
0.24
|
(iii) Dockyard
|
= 0.16
|
|
|
|
|
(iv) Railway Platform
|
= 0.24
|
|
|
|
|
(v) Foot- path
|
= 0.40
|
Table 8: Abrasion test results of Grouted Macadam sample
6.6) Evaluation Of Grouted Macadam Vis-Vis Designed
Bituminous Material.
Bituminous mixes used
as surface courses of flexible pavement are visco-elastic materials and their
properties are dependent upon stress, strain and temperatures. The induced
strain in a bituminous material is attributable to viscous flow and increases with
loading time and temperature.
The other vital issue
associated with failure of bituminous surfacing is loss of adhesion between
binder and aggregate under the influence of water and also due to spillage of
petroleum fuel from vehicles. The bituminous mixes have to fulfill a wide range
of requirements to sustain traffic and environmental stresses. These are the resistance to permanent deformation and
fatigue \cracking, impermeable to protect lower layers of road from water,
durable to resist abrasion of traffic and effects of temperature., water and
oil spillage and contribute to pavement strength. It is important to study
effect of water, temperature and oil on a material while comparing a new
material like Grouted Macadam for its performance vis-vis bituminous material.
The properties of Grouted Macadam vis-vis Bituminous concrete (BC) using 60/70 grade bitumen used for aggregate
coating are given in Table 9
|
Properties
of Grouted Macadam vis-a-vis Bituminous Concrete using 60 / 70 grade bitumen
|
|
Properties
|
Values
of BC using
Bitumen
60 / 70
|
Grouted
Macadam
|
Limits
MORT
& IRC specification
|
|
Bulk
density, gm/cc
|
2.34
|
2.32-2.35
|
|
|
Marshall Stability , at 600C,
kg, (ASTM D 1559)
|
940
|
2270
|
820 (min)
|
|
Marshall flow at 600C, mm,
(ASTM D 1559)
|
3.2
|
4.2
|
2.0 - 4.0
|
|
Percent Air voids
|
4.2
|
|
3.0 - 6.0
|
|
Indirect tensile strength at 250C
, kg /cm2
|
5.7
|
13.8
|
ASTM D 4123
|
|
Stiffness Modulus at different
temperatures, kg/cm2 Poisson’s Ratio (m) = 0.35for bituminous materials and 0.25
for Grouted Macadam (ASTM D 4123)
|
150C
|
50920
|
184620
|
IRC - 37 - 2001 indicated value of elastic
modulus of BC mix as 31260 kg / cm2 for 60/70 and 19660
kg/cm2 for 80/100 bitumen at 25oC
|
|
250C
|
24990
|
100390
|
|
350C
|
10640
|
79650
|
|
450C
|
1920
|
54530
|
|
Reduction in stiffness modulus values , %,
(150C - 450C )
|
96
|
71
|
Not specified
|
|
Retained stability at 600C
immersion in water at 600C for 24 hours , % , ( ASTM D 1075)
|
80
|
93
|
75 (min)
|
|
Retained
indirect tensile strength at 250C immersion in water at 600C
for 24 hours , %, (ASTM D 4867)
|
85
|
95
|
80 (
min )
|
|
Loss of
material in diesel oil , 7 days immersion , %
|
4.2
|
0.3
|
Not
specified
|
Table 9 properties of
Grouted Macadam vis-vis Bituminous concrete (BC) using 60/70 grade bitumen
Fig 9: Elastic Modulus (MPa) of Bituminous Materials
and ACCMarg
Few illustrative pictures of Indian road before and after overlaying with
Grouted Macadam are given below
Fig
12: Typical road with potholes
Fig 13: A
bridge deck of Mumbai-Pune Expressway after overlaying with Grouted Macadam
VII) Conclusion
UTWT and
Grouted Macadam are two proven technologies for Indian infrastructure. The
grouted macadam was first used by Mumbai Municipal Corporation in the year 2000
and Surat Municipal Corporation is using it even in the year 2013.
The UTWT is first laid in Thane Municipal
Corporation and TMC is using the same technology even in the year 2013.These
two technologies are replacement to existing bituminous road.
Acknowledgement
1) The author acknowledges ACC Ltd where author has
the opportunity to work on these two technologies.
2) The author also acknowledge Mr.K.D.Lala city
engineer TMC for allowing to lay the trail patch of UTWT in Thane city in the
year 2007l
3) The author acknowledge Mr.P.Bongirwar for
introducing white topping in rural roads under the
scheme PMGSY
References
1) Dr Vilas Deshmukh 2011, “UTWT
for Eco-Friendly Roads” in Construction Business Today Vol No1 No 3 June
2) V.K. SINHA*, SATANDER KUMAR**
& R.K. JAIN***.“White Topping A Cost effective rehabilitation alternative
for preserving bituminous pavements on long term basis” Paper in Indian Road
Congress paper no Paper No. 538
3)Road Research Road Note No.27, "Instruction
for using British Portable Skid Resistance Tester" Department of
Scientific and Industrial Research, RRL HMSO London, 1960
4) NCHRP Report No.37, “Tentative
skid resistance requirements for main rural highways, HRB”, 1967.
5) Method of Test of Abrasion
resistance of concrete as per IS 9284-1979
6) ASTM D 4867
7) ASTM D 1075 and ASTM D3637
8) ASTM D 4123 and ASTM D 1559
9) Assessment of LTPP friction
Data, US Department of transportation, FHWA March 1999
10) The program which was telecast on
DD SAHYADRI TV channel can be viewed here http://www.youtube.com/watch?v=nCBFqbx9RRA&feature=plcp
