International Journal of Scientific & Engineering Research, Volume 4, Issue 9, September-2013 72

ISSN 2229-5518

Evaluation of Cost Effective Material for

Maintenance of Flexible Pavement

Mr. Sagar B. Patil1, Prof. Dhananjay S. Patil2

Abstract— Pavements represent an important infrastructure facility in all countries. Two important parameters for good pavements are pavement design and materials. A good design of bituminous mix is expected to result in a mix which is adequately strong, durable and at the same time environment friendly and economical in order to maintain the pavement.

This work is undertaken to prepare cost effective material for maintenance of flexible pavement. By using industrial wastes steel slag and foundry sand as a replacement material for fine aggregate in bituminous mix and ground granulated blast furnace slag as a replacement material for fillers in bituminous mix. Fillers play an important role in engineering properties of bituminous paving mixes. Conventionally stone dust, cement and lime are used as fillers.

Index Terms— steel slag, ground granulated blast furnace slag, foundry sand

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1 INTRODUCTION

oads are very important national investment and require maintenance to keep them in a satisfactory condition and ensure safe passage at an appropriate speed and with low road user cost. Late or insufficient maintenance will in-
crease the ultimate repair costs, inconvenience and reduce
safety. Pavement maintenance is therefore an essential func-
tion and should be carried out on a timely basis. From the
budget allocation plan of India the amount for maintenance and repairs of highways is Rs. 1089.49 crores in 2010-2011 and Rs. 1272.49 in 2011-2012 for a length of 33,20,596 km. Hence amount of maintenance per kilometre in 2010-2011 is Rs. 3281 and in 2011-2012 is Rs.3832. is it sufficient for pavement maintenance? It is necessary to develop cost effective material for pavement maintenance.
Generally a bituminous mixture is a mixture of coarse ag-
gregate, fine aggregate, filler and binder. Two things are of
major considerations in flexible pavement engineering–
pavement design and the mix design. A good design of bitu-
minous mix is expected to result in a mix which is adequately (i) Strong (ii) Durable (iii) Resistive to fatigue and permanent deformation (iv) Environment friendly (v) Economical. A mix designer tries to achieve these requirements through a number of tests on the mix with varied proportions and finalizes with the best one.

Objective of Bituminous Mix Design:

Bituminous concrete consists of a mixture of aggregate contin- uously graded from maximum size , typically less than 25 mm, through the fine filler that is smaller than 0.075 mm. Suf- ficient bitumen is added to the mix so that the compacted mix will have acceptable elastic properties. The bituminous mix design aims to determine the proportion of bitumen, filler, fine aggregate, and coarse aggregate to produce a mix which is

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• Mr. Sagar Bhimrao Patil is currently pursuing masters degree program in M. Tech. Civil, R I T Sakharale, Dist. Sangli, Maharashtra state, India. (email:sagarpatil.civil47@gmail.com)

• Prof. Dhananjay S. Patil is currently Associate Professor, Department of Civil Engineering, Rajarambapu Institute of Technology,Rajaramnagar, Islampur, Dist. Sangli, Maharashtra, India

workable, strong, durable and economical. The objective of the mix design is to produce a bituminous mix by proportioning various components so as to have-
1. Sufficient bitumen to ensure a durable pavement
2. Sufficient strength to resist shear deformation under
traffic at higher temperature
3. Sufficient air voids in the compacted bitumen to allow
for additional compaction by traffic
4. Sufficient durability
5. Should be economical.

2 INTRODUCTION TO FLEXIBLE PAVEMENT MAINTAINANCE:

2.1 Meaning of Flexible Pavements:

Flexible pavements are constructed of several layers of natural granular material covered with one or more water- proof bituminous surface layers, and as the name imply, are considered to be flexible. A flexible pavement will flex (bend) under the load of a tyre. In flexible pavements, the load distri- bution pattern changes from one layer to another, because the strength of each layer is different. The strongest material (least flexible) is in the top layer and the weakest material (most flexible) is in the lowest layer.

2.2 Pavement deterioration and its types:

Pavement deterioration is the process by which distress (defects) develop in the pavement under the combined effects of traffic loading and environmental conditions. Distresses in flexible pavement are as follows:

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ISSN 2229-5518

13. Patching 14. Polished Aggregate

15. Water bleeding and pumping

2.3 Main Causes of Distresses In Pavement:

1) Traffic
2) Environmental condition
3) Method of construction and quality of construction material
4) Moisture infiltration.
Pavements fail prematurely because of many factors, there are
four primary reasons pavements fail prematurely:
• Failure in design
• Failure in construction
• Failure in material
• Failure in maintenance

2.4 Conventional Material used for Maintenance of

Flexible Pavement:

1. Slurry Seal Coat:

Slurry seal consists of a mixture of sand, Portland ce- ment, water, and emulsified asphalt mixed to a rich consisten- cy. It is spread in a thin layer over the pavement. Portland cement is added for stabilizing and setting the slurry. Slurry seal coats are normally used to fill cracks and minor depres- sions in older AC pavement.

2. Emulsified asphalt:

Emulsified asphalt is a mixture of asphalt cement and water. This asphalt/water ratio is about 60/40. The bitumen content in the emulsion is around 60% and the remaining is water. Sometimes a special type of emulsified asphalt is speci- fied in the Special Provisions. The special type of emulsified asphalt is 50/50 mixture of water and emulsified asphalt. An asphalt emulsion consists of three basic ingredients: asphalt, water, and an emulsifying agent.

3. Final seal (Rubber crumb slurry):

A slurry seal, using rubber crumbs instead of aggregate can be used to fill the wider active cracks. Hand tools are used to mix and apply this slurry seal.
The slurry consisted of the following mix by volume:
• Rubber crumbs 60%
• Stable grade bitumen emulsion 35%
• Cement 5%.

4. Micro surfacing:

Micro surfacing is a mix of polymer-modified emul- sion, well-graded crushed mineral aggregate, mineral filler (normally Portland cement), water, and chemical additives. The aggregate, mineral filler, emulsion, and water are mixed in a truck-mounted travelling plant, which is deposited into a spreader box. No compaction is needed, traffic may be al- lowed over the application within an hour after placement.

5. Pothole repair material:

The four components of a typical mix are:
• Coarse aggregate (retained on 2.36mm sieve)
• Fine aggregate (passing 2.36mm sieve but retained on
75µ)
• Filler (passing 75µ), may be cement.
• Binder: Bitumen etc.

6. Stone Mastic Asphalt (SMA) Mortar:

Mixture of asphalt cement (and any additives), filler (all material passing through 75 μ sieve) and fibres blended by volume.

3. EXPERIMENTAL STUDY

3.1 Material Used:

1. Steel Slag:

Steel slag, a by-product of steel making, is produced dur- ing the separation of the molten steel from impurities in steel- making furnaces.

2. Ground granulated blast furnace slag:

Blast Furnace Slag is a by product obtained in the manufac- turing of Pig iron in the Blast furnace and is formed by the combination of earthy constituents of iron ore with lime stone flux. Quenching process of molten slag by water is converting it into a fine, granulated slag of whitish colour.

3. Foundry sand:

Sand is used in the foundry industry mainly for making moulds for the casting. This sand is generally recycled. After a repeated use, they lose their characteristics and thereby be- coming unsuitable for further use in manufacturing process. This sand is usually discarded and dumped in the landfill as a waste.

4. Course aggregate:

The mineral aggregate most widely used in bitumen mixes are crushed stone, crushed or uncrushed gravel. Since mineral aggregate constitutes of approximately 88% to 96% by weight and approximately 80% by volume of the total mix. Their in- fluence upon the final characteristics of bituminous mixes is very great

5. Fine aggregate:

It shall be fraction passing 2.36 mm and retained on 75 µ sieve consisting of crushed stone or natural sand. Its function is to fill up the voids of the coarse aggregate. Here in this work natural sand is used as fine aggregate. It should be clean, hard, strong, free of organic impurities and free of silt and clay.

6. Cement:

It is the filler material used in bituminous mix which pass- es through 75 µ sieve. The fillers should be inert material. The cement should be fresh, have uniform consistency and free of lumps and foreign matter.

7. Bitumen:

Bitumen is the residue or by-product when the crude pe- troleum is refined. Bitumen is act as a binder in bituminous mix. Different grade of bitumen are used in different mix. Here we used 60/70 bitumen for preparation of bituminous mix.

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3.2 Test Results:

1. Coarse Aggregate:
1. Water Absorption= 0.406%
2. Specific Gravity= 2.96
3. Fineness modulus = 7.49
2. Fine Aggregate:
1. Water Absorption= 1 %
2. Specific Gravity= 2.66
3. Fineness modulus = 2.57
3. Cement:
1. Fineness Test = 7%
2. Specific gravity= 3.15
4. Steel slag:
1. Water Absorption= 0.95%
2. Specific Gravity= 2.89
3. Fineness modulus = 3.29
5. Foundry sand:
1. Specific Gravity= 2.43
2. Fineness modulus = 3.091
6. Ground granulated blast furnace slag:
1. Specific Gravity= 2.94
2. Fineness Test = 6.5%

4. TESTING OF BITUMINOUS MIX AND RE- SULTS:

4.1: Brief Procedure of Marshall Test:

1. 1200gm aggregate are weighted and heated up to 154-
160 degree C.
2. Bitumen is heated 175 -190 degree C.
3. Aggregate & Bitumen are mixed thoroughly until a
uniform grey colour is obtained.
4. Marshall Mould diameter 100mm & 64mm ht com-
pacted with 75 blows on each face.
5. Mould is taken out kept under normal laboratory
temp for 12 hours.
6. It is immersed in water bath kept at a constant temp
60 degrees for 30 minutes.
7. Load is applied vertically at the rate of 50mm per
minute.
8. The maximum load at sample fails is recorded as the
Marshall Stability value.
9. Corresponding vertical strain is termed as the flow
value.

4.2: Test Procedure:

A specimen from the Water bath is removed and placed in the lower segment of the testing head. The upper segment of the testing head on the specimen is placed, and the complete assembly is paced in position in the loading machine. The dial gauge is placed in position over one of the guide rods. Read- ings of dial gauge and proving ring are recorded.

4.3: Parameters used:

1. Theoretical Maximum Specific Gravity of Mix:

Gt = 100/ (W1/G1+W2/G2+W3/G3+W4/G4) Where,
W1 = Percentage by weight of coarse aggregate in total mix
W2 = Percentage by weight of fine aggregate in total mix
W3 = Percentage by weight of filler in total mix
W4 = Percentage by weight of bitumen in total mix
G1 = Specific gravity of coarse aggregate
G2= Specific gravity of fine aggregate
G3= Specific gravity of filler
G4= Specific gravity of bitumen.

2 Bulk Density of mix:

Gm = weight in Air / (weight in air – weight in water) * 1 gm/ cm3

3 Volume of air voids:

Vv = ((Gt – Gm) / Gt) * 100

4 Voids in Mineral Aggregate (VMA):

VMA = Vv + Vb
Where,
Vv = Volume of air voids, Vb = Volume of bitumen.

5 Voids Filled With Bitumen (VFB):

Vb= Gm*(W4/G4) Where,
Gm = Bulk Density
W4 = Percent by weight of bitumen in total mix
G4= Specific gravity of bitumen.

4.4: Marshall Test Results:

The results of the Marshall test of samples and average Mar- shall Properties of Samples prepared with conventional mix for varying bitumen contents have been presented below:

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TABLE 5.1 RESULTS OF MARSHALL TEST FOR CONVENTIONAL MIX

From the test results optimum binder content selected as 6.5%.

TABLE 5.2 RESULTS OF MARSHALL TEST FOR REPLACEMENT OF FINE AGGREGATE AND FILLER MATERIAL BY 50%

TABLE 5.3 RESULTS OF MARSHALL TEST FOR 60%

REPLACEMENT OF FINE AGGREGATE AND FILLER MATERIAL (STEEL SLAG AS A FINE AGGREGATE AND GGBFS AS A FILLER MATERIAL)

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TABLE 5.4 RESULTS OF MARSHALL TEST FOR 70%

REPLACEMENT OF FINE AGGREGATE AND FILLER MATERIAL (STEEL SLAG AS A FINE AGGREGATE AND GGBFS AS

A FILLER MATERIAL)

TABLE 5.5 RESULTS OF MARSHALL TEST FOR 80%

REPLACEMENT OF FINE AGGREGATE AND FILLER MATERIAL (STEEL SLAG AS A FINE AGGREGATE AND GGBFS AS A FILLER MATERIAL)

TABLE 5.6 RESULTS OF MARSHALL TEST FOR 60%

REPLACEMENT OF FINE AGGREGATE AND FILLER MATERIAL (FOUNDRY SAND AS A FINE AGGREGATE AND GGBFS

AS A FILLER MATERIAL)

TABLE 5.7 RESULTS OF MARSHALL TEST

70% REPLACEMENT OF FINE AGGREGATE AND FILLER MATERIAL (FOUNDRY SAND AS A FINE AGGREGATE AND GGBFS AS A FILLER MATERIAL)

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TABLE 5.8 RESULTS OF MARSHALL TEST

80% REPLACEMENT OF FINE AGGREGATE AND FILLER MATERIAL (FOUNDRY SAND AS A FINE AGGREGATE AND

GGBFS AS A FILLER MATERIAL)

TABLE 5.9 RESULTS OF MARSHALL TEST

REDUCTION OF COARSE AGGREGATE BY 20% AND REPLACING ALL FINE AGGREGATE WITH 50% STEEL SLAG AND 50% FOUNDRY SAND (USING CEMENT AS FILLER)

TABLE 5.10 RESULTS OF MARSHALL TEST

REDUCTION OF COARSE AGGREGATE BY 20% AND REPLACING ALL FINE AGGREGATE WITH 70% STEEL SLAG AND 30% FOUNDRY SAND (USING CEMENT AS FILLER)

1. The results for Marshall Stability with 60% replacement of fine aggregates using steel slag are more as compare to other trials; the stability values obtained are 495 kg, 492 kg, and 492 kg.
2. The results for Marshall Stability with 50% replacement of
fine aggregates using foundry sand are more as compare
to other trials made with foundry sand, the stability val-
ues obtained are 472 kg, 470 kg, and 472 kg.
3. Therefore optimum percentage replacement obtained
from Marshall Test results for steel slag is 60% and for
foundry sand is 50%.

5. COST COMPARISON OF MATERIAL

5.1: For Conventional Mix:

Considering for 10 m2 area:
Quantities of aggregate for 10 m2 area is 0.27 m3,
56 kg bitumen used per m3, for 0.27 m3 of
Aggregate= 15.12 kg bitumen is required, Volume of aggregate= 0.27m3
1. 10 mm-4.75mm 80% = 0.21 m3 *1050
= Rs. 220.50
2. 4.75 mm-75 µ 15% = 0.04 m3*1120
= Rs.44.80
3. Filler @ 5% = 0.020 m3*925

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= Rs. 18.50
Total cost of aggregate = 0.27 m3
= Rs. 283.80
Cost of bitumen = 15.12 kg
= 0.0151 tonnes*42000
= Rs.635.04

Total cost of mix = Rs. 918.84

It is the cost for normal mix.

5.2: Cost for Mix made with Steel Slag and Foundry

Sand:

Volume of aggregate = 0.27m3
1. 10 mm- 4.75mm 60% = 0.162 m3*1050
= Rs.170.10
2. 4.75mm-75 µ (50-50%)
Steel slag = 0.054*200
= Rs. 10.80
Foundry sand = 0.054*150
= Rs. 8.10
3. Filler @ 5% = 0.020 m3*925
= Rs. 18.50
Total =0.27 m3 = Rs.207.5
Cost of bitumen =15.12 kg
= 0.0151 tonnes*42000
= Rs.635.04

Total cost of Mix = Rs.842.5

Therefore saving in cost per10 m2 is Rs.94.39 by using steel
slag and foundry sand replacement for fine aggregates in bi-
tuminous mix by reducing 20% of coarse aggregates. Hence
saving in cost for 1 m2 is Rs.9.43.

6.0 CONCLUSIONS:

1. From the result and analysis of various properties of steel slag and foundry sand it is found that these ma- terials can be used as fine aggregates as replacement for natural sand and ground granulated blast furnace slag can be used as filler material as replacement for cement in bituminous mix.
2. Bituminous mixes prepared using conventional mix
at different bitumen content gives the optimum bitu-
men content as 6.5%.
3. Bituminous mixes prepared with 50% replacement of fine aggregates with steel slag and 50% replacement of cement with GGBFS gives the Marshall Stability value as 500 kg which is 30 kg more as compare to the other mixes.
4. Bituminous mixes prepared with 60% replacement of fine aggregates with steel slag gives the Marshall Sta- bility value as 495 kg, 492 kg, 492 kg which are high as compare to the other trials.
5. Saving in cost per 1 m2 is Rs.9.43 by using steel slag
and foundry sand replacement for fine aggregates in bituminous mix by reducing 20% of coarse aggre- gates.
6. By using steel slag and foundry sand in bituminous mix an environmental effects from wastes and dis- posal problems of waste can be reduced.

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