Rural roads mostly bituminous roads are in bad shape because of severe climatic conditions in our country. Funds for maintenance are not available resulting very bad condition of road in our country. The concrete roads are recommended for our country because 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 is very 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 rate
According to Mr.P.Bongirwar out of 33lack km of length only 2lakh kilometre carry heavy traffic from 30MSA to 200 MSA and only about 50000 kilometre may be carrying more than 100 MSA. Majority of village roads and ODR 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 grands.
omt 90% length is metalled and top WBM layer is seriously affected and not in traffic worthy condition .The black topped village roads are also heavily damaged due to lack of renewal coat. 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 road is usually provided with thin bituminous surfacing which require constant maintenance of potholes formed during rains. The road 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.
The author has categorised the village roads as roads villages turning cities and village roads.
The city roads The traffic of the city road is of cars ,rickshaws, buses, trucks etc. The axle load is of 10MSA.The thickness of the road is 100mm based on IRC -78. The optimum mix design is given below.
Historical development in urban pavement technology at TMC
MIX DESIGN FOR WHITE TOPPING AS OVERLAY
for TMC CORPORATION
MATERIAL
|
kg/M3
|
RS/KG
|
COST
|
DENSITY
|
VOLUME
|
cement
|
360
|
6.00
|
2160
|
3.15
|
114.29
|
flyash
|
150
|
2
|
300
|
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
|
140
|
420
|
1.23
|
2.44
|
water
|
160
|
0.4
|
64
|
1
|
160.00
|
fiber
|
0
|
225
|
0
|
1031.51
| |
2590
|
4094.2
|
COMPRESSIVE STRENGTH
|
7-DAYS
|
25mpa
| |
28-days
|
40mpa
| ||
510.00
| |||
water/powder
|
0.88
|
88
| |
past content
|
0.33
|
36
| |
sand content
|
0.33048015
|
35
| |
coarse aggregate
|
0.33661683
|
28
| |
.THIN WHITE TOPPING IS GRDUALLY BECOMING POPULAR IN URBAN AREAS The author has developed the above mix design and first time laid 100meter stretch of white topping in thane city in the year 2008.The project was successful and 25 kilometre white topping is done in thane city .The methodology is given below. The life cycle study certainly prove that white topping is cheaper than conventional bituminous roads
FIG1 Milling of existing bituminous road
FIG2 Sub base preparation
Fig3 concrete laying
FIG4 UTWT Topping
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 The concrete used was totally different than conventional concrete.
1. 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.
2. The SCC technology is used to achieve concrete to spread of its own weight.
3. First time the joint cutting is avoided by placing geopolymer strips of 50mm in 150mm concrete at regular interval.
Three fundamental changes in concrete technology made it possible to give concrete roads to villages in 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 concrete road at kunde bangar wadi under the scheme of prime minister of gram Sadak yogna
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
|
140
|
420
|
1.23
|
2.44
|
water
|
150
|
0.4
|
60
|
1
|
150.00
|
994.97
| |||||
2519
|
3584.85
|
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
Gradation for metal i&ii
|
metal ii
|
metali
|
%passing
| ||
20mm
|
95-100
|
100
|
16mm
| ||
12.5mm
|
90-100
| |
10mm
|
25-55
|
40-85
|
4.75mm
|
0-10
|
0-10
|
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.
Historical work carried out in Bhangarwadi village near kalyan.is given below
FIG1 Mixer for making concrete,FIG2 Laying of channelFIG3 Placing of concreteFIG4Authorities inspecting the roadFIG5Ready to use road
For village roads normally crust consist of 300mm sub grade ,200mm GSB,150-
to 225 mm WMM 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 cmber.20mm carpet and seal coat is added as wearing course
As an alternate to above the levelling course itself could be converted in to white topping layer the structure could be on line of white topping technology.
The WBM of hand broken material/crushed aggregates of proper gradation are laid it will then be rolled and compactedThe entire surface then will be grouted with specially designed flow table grout and compacted again.
Rate analysis of technology similar to coalcrete
length
|
1000
|
m
| ||||
breadth
|
3
|
m
| ||||
thick
|
0.05
|
m
|
volume m3
|
150
| |||||
voids%
|
30
| |||||
total voids m3
|
45
| |||||
grout quality
|
%
|
m3
|
kg
|
ton
|
cost/ton
|
cost in Rs
|
cement
|
20
|
8.955224
|
19701.49
|
19.70149
|
5600
|
110328.4
|
aggrgate
|
70
|
31.34328
|
68955.22
|
68.95522
|
700
|
48268.66
|
flyash
|
10
|
4.477612
|
9850.746
|
9.850746
|
1800
|
17731.34
|
admix
|
0.5
|
0.223881
|
1100
|
1.1
|
150000
|
165000
|
sf
|
0
|
0
|
0
|
0
|
28000
|
0
|
total
|
341328.4
|
grout density
|
2200kg/m3
| |||||
cost in Rs
| ||||||
aggregate in tons
|
211.5
|
211500
| ||||
aggregate cost
|
211500
|
211500
| ||||
552828.4
| ||||||
box making with geopolymer
|
50000
| |||||
labour and machinery
|
110565.7
| |||||
tax
|
27641.42
| |||||
profit 20%
|
110565.7
| |||||
851601.1
| ||||||
m3
|
5677.341
| |||||
sq.meter
|
283.867
| |||||
FIG1Mixing of fine powder materials,FIG2 Spreading of hand broken stones across the damaged road,FIG3 Grout prererationFIG4 Pouring the groutFIG5Final road
The cementitious grouts
The high quality cheaper grouts are prepared. In order to keep the cost of the grout competitive additives like flyash, GGBS are used in large proportion. In order to keep the grout in suspension polymer based admixture is used..the pore volume is adjusted using lower size stone.
Few compositions of high strength cementitious grouts are given below
Compressive strength test results of grouts with Tata flyash
| ||||||||
CEMENT
|
55
|
55
|
45
|
45
| ||||
TFA
|
40
|
45
|
55
|
50
| ||||
SF
|
5
|
5
| ||||||
ADDITIVE
|
0.5
|
0.5
|
0.5
|
0.5
| ||||
WATER
|
20.6
|
20.3
|
18.3
|
18.6
| ||||
STRENGTH Kg/Cm2)
| ||||||||
1-Day
|
244
|
208
|
102
|
165
| ||||
3-Day
|
728
|
755
|
599
|
543
| ||||
7-Day
|
753
|
879
|
760
|
672
| ||||
28-Days
|
Results awaited
| |||||||
The grout using TATA flyash can achieve compressive strength of 100Mpa.
Comparison of modified grouts compositions with normal grout using SF
composition
|
Gr-II
|
50cement
|
35cement
|
30cement
|
45cement
|
50pozo
|
65pozo
|
70pozo
|
30pozo
| ||
30Dahanu
| |||||
comp.strength
| |||||
1-Day
|
199
|
293
|
189
|
133
|
134
|
3-Days
|
433
|
436
|
300
|
248
|
316
|
7-Days
|
528
|
526
|
450
|
430
|
480
|
28-Days
|
633
|
Pozocrete micronized flyash can replace costly silicafume
Trials conducted using slag cement
Slag cement
|
55
|
60
|
65
| ||||
flyash
|
40
|
35
|
30
| ||||
SF
|
5
|
5
|
5
| ||||
Additive
|
0.5
|
0.5
|
0.5
| ||||
water
|
27
|
26
|
25
| ||||
Compressive strength(kg/cm2)
| |||||||
1-Day
|
54
|
85
|
114
| ||||
3-Days
|
185
|
233
|
321
| ||||
7-Days
|
275
|
330
|
522
| ||||
28-Days
|
530
|
650
|
710
| ||||
Preparation of base for roads;
The damaged bituminous roads are cleaned and milled using milling machine. The 50mm thick of 30mm stone are laid on the damaged bituminous roads. rolled with vibratory roller and the high strength grout is poured in to the pores of the aggregate bed.
The 30mm aggregates are even prepared from the rock at site by hand braking.This will provide employment to rural youth.
The high quality cheaper grouts are poured into the 30mm stone laid on the damaged roads. rolled with vibratory roller and the grout is penetrated into the pores of the bed
The compressive and flexural strength of such roads tested inlab is found to be 40Mpa and 4.25Mpa respectively
It is observed that during the testing of compressive strength at some occassion the aggregates were fractured keeping the matrix strong.
Cost of the grout is Rs 4/kg which can be further reduced by at least one rupee by having dialog with admixture manufacturers.
The grout composition
material
|
Gr-1
|
Gr-2
|
cement
|
55
|
45
|
flyash
|
45
|
55
|
admixture
|
0.5
|
0.5
|
water
|
30
|
30
|
The cost of square meter road.
The cost of the road is approximately Rupees 350 per meter square.
The technology is rural friendly it requires only blender for grout preparation and pump to deliver the grout at site. Unskilled labour to brake the stone and labour to pour the grout. The cost can further be reduced.
IN THIS TECHNOLOGY THE 40MM STONE ACT AS SOLD PLASTIC CELL .AND THE GROUT RESTRICTS THE BOUNDRIES.
WE CAN SAVE THE ADDITIONAL COST OF PLASTIC CELL.
Conclusion
1) Affordable technologies are readily available to use
2) The citizen of India should examine these technologies
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