Bangalore is facing problems due to old municipal solid waste dump yards situated close to the expanding city as they are in the expansion zone of growing city. These dump yards needs to be reclaimed for infrastructure development such as roads, buildings and other needs. To reclaim the old dump sites, it is necessary to know the characteristics of solid waste, more particularly the geotechnical properties. The characteristics of dumps sites are not generally suitable for foundations of most types of structures coming on them and their properties need to be improved. Also their characteristics vary change with aging due to their degradation. This paper presents the results of stabilization of dumped waste by addition of pozzolanic material such as fly ash. Laboratory tests such as Direct shear and California Bearing Ratio (CBR) have been performed on dumped waste with fly ash. It was found that addition of 20% of fly ash the shear strength of dumped waste has increased considerably. Also CBR of stabilized waste dumps, which is important in the reclamation of dumped sites, has been analyzed. It was that CBR of stabilized dumps was higher value for 5 mm penetration than for 2.5 mm penetration and tests were conducted to confirm the same. It was observed that the improvement in CBR is promising and further studies are required to improve to the material to form suitable for foundations.

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STABILIZATION OF WASTE DUMP USING FLYASH
B. P. Naveen1
, P.V.Sivapullaiah2
, T.G.Sitharam3
and A.K. Sharma4
1, Research Scholar, Dept. of Civil Engg. IISc, Bangalore,
Email: bpnaveen@civil.iisc.ernet.in
2, Professor, Dept. of Civil Engg.,IISc, Bangalore,
Email: siva@civil.iisc.ernet.in
3, Professor, Dept. of Civil Engg.,IISc, Bangalore,
Email: sitharam@civil.iisc.ernet.in
4, Research Scholar, Dept. of Civil Engg. IISc, Bangalore,
Email:anilkr@civil.iisc.ernet.in
ABSTRACT: Bangalore is facing problems due to old municipal solid waste dump yards
situated close to the expanding city as they are in the expansion zone of growing city. These
dump yards needs to be reclaimed for infrastructure development such as roads, buildings and
other needs. To reclaim the old dump sites, it is necessary to know the characteristics of solid
waste, more particularly the geotechnical properties. The characteristics of dumps sites are not
generally suitable for foundations of most types of structures coming on them and their
properties need to be improved. Also their characteristics vary change with aging due to their
degradation. This paper presents the results of stabilization of dumped waste by addition of
pozzolanic material such as fly ash. Laboratory tests such as Direct shear and California
Bearing Ratio (CBR) have been performed on dumped waste with fly ash. It was found that
addition of 20% of fly ash the shear strength of dumped waste has increased considerably. Also
CBR of stabilized waste dumps, which is important in the reclamation of dumped sites, has been
analyzed. It was that CBR of stabilized dumps was higher value for 5 mm penetration than for
2.5 mm penetration and tests were conducted to confirm the same. It was observed that the
improvement in CBR is promising and further studies are required to improve to the material to
form suitable for foundations.
KEYWORDS: California Bearing Ratio, Direct shear, Municipal solid waste, Waste dump
INTRODUCTION:
Solid Waste Management is a very complex common problem in both developing and
developed countries. Improper management in developing countries results in dirty public areas,
waste recovery in the streets, dumping of garbage into streams and rivers, or open dumps leading
to men, women and children made through the waste subjecting all of them to all kinds of
diseases and accidents. The problem is aggravating due to rapid population growth, industrial
development and changing eating habits and wide spread use of disposable containers. Many
cities including Bangalore are also facing problems due to old dump yards situated close to the
expanding cities (Naveen et al. 2013). These dump yards needs to be reclaimed for growing
needs of the city infrastructure development. Already several of them have been reclaimed

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without proper improvement causing distress to structures founded on them. To reclaim the old
dump sites it is necessary to know the intrinsic qualitative and quantitative characteristics of
solid waste as its increase demands alternative methods of handling, treatment and disposal. The
characteristics of waste change with aging due to their degradation with aging.
Geotechnical properties of the waste from dump site are generally don’t possess adequate
geotechnical properties to support foundations for infrastructure development activities. Most of
the prior dump sites have been reclaimed without proper treatment for laying road and
construction of foundation, many residential and industrial structures (Naveen et al, 2014).
These structures undergo large settlements and may also cause several failures. Further most of
the dumpsites or reclaimed for road works.
Need for Stabilization of dumped Waste for Pavements
Thus, there is a need to improve the geotechnical properties of waste particularly the
waste dump sites for road reclamation. Most commonly available and used stabilizing material
is Flyash and is very important in the reclamation of Dumped sites.
Flyash is a pulverized product from thermal power plants generated by the burning of
coal. Indian Power plants burn about 500 million tons of coal per year and produces 200 million
tonnes of fly ash at present, which shall grow by 900 mtpa (coal) and 350 mtpa (fly ash) by
2020. Most of the fly ash presently produced by electric utilities and industry is land filled or
stored in disposal ponds. The production of Fly ash is expected to increase to about 200 MT per
year by the year 2020. This would require about 4000 ha of land for the construction of ash
ponds. Generally one acre of land is required per megawatt of power generation. Continuous
studies have been carried out in India towards management of fly ash (FA), disposal and
utilization. Fly ash could be a cost effective substitute for Portland cement in some markets. In
addition, fly ash could be recognized as an environmentally friendly product, because it is a by-
product and has low embodied energy. According to the American Coal Ash Association
(ACAA), the largest utilization application of coal combustion fly ash is in concrete, concrete
products and grout. But Fly ash has also been used recently for paving roads, and as embankment
and mine fills. There are mainly two types of fly ash. Class F are generally low-calcium fly ashes
with carbon contents less than 5% but sometimes as high as 10%.Class C fly ash has a higher
percentage of calcium oxide and is more commonly used for structural concrete. Class C fly ash
normally is composed of high-calcium fly ashes with carbon content less than 2%. Though Fly
ash has been used in the above mentioned areas, its utilization in the field of stabilization of
dumped wastes is not explored.
Requirement for Road Reclamation
Almost all of road network in India consists of flexible pavements. The design of flexible
pavement is generally designed using California Bearing Ratio (CBR).

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Fig. 1.A Typical cross section of a flexible pavement
The performance of a pavement structure is related to the strength of underlying sub grade
layers. Fly ash is used to stabilize soils and is used in different layer of flexible pavements. Fly
ash compacted at optimum moisture content for a given compactive effort will have dry density
at its maximum and consequently the maximum shear strength. Strength in the form CBR values
forms an important basis for construction of many type of road construction. Typical layers of a
conventional flexible pavement includes seal coat, surface course, tack coat, binder course, prime
coat, base course, sub-base course, compacted sub-grade, and natural sub-grade (Fig. 1). For
flexible pavement, as per IRC 37:2001, design sub grade CBR values ranges from 2% to 10%
and design traffic ranges from 1 msa to 150 msa for an average annual pavement temperature of
35 degree centigrade. From the knowledge of several information and records of the pavement
thickness and the values of C.B.R and its suitability for the expected traffic volume, the correct
thickness can be designed (Table 1). Thus from this table it is found that CBR of 4 to 7% can
used as soil sub grades.
Table.1 Typical design CBR values for pavements
Layer Design CBR (%) Thickness
Bituminous Surfacing -- 8
Well graded gravel 95 13
Poorly graded gravel 20 19
Compacted Soil
Subgrade
7 15
Soil Subgrade 4 --
LITERATURE REVIEW
Stabilization refers to those techniques that reduce the hazard potential of a waste by
converting the contaminants into their least soluble, mobile, or toxic form. Significant
contributions have been done in the field of stabilization of contaminated soil using cement, fly
ash, etc. (Malviya and Chaudhary, 2006; Kogbara et al. 2003). But due to increasing cost of
cement, it is not encouraged to be utilized in such applications. Hence industrial waste materials
are being promoted which not only reduces disposal problems but will be economical also.

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Depending upon the specific chemical properties cementitious based materials have been used to
treat soils/sludge contaminated with semi volatile organic contaminants. But studies related to
the stabilization of MSW are not known. Bookter and. Ham (1982) has discussed about a method
for the analysis of refuse stability has been developed and tested by analyzing refuse obtained
directly from test lysimeters and actual landfills across the United States. Results obtained from
the actual landfill situations are compared to those obtained from the test lysimeters of known
refuse age in order to determine the degree of refuse stability in each landfill in relation to depth
and location. Also, the results obtained from landfills of different geographical locations,
different climatic situations, and different configurations are compared. Stabilization treatment
can be done in different processes such as sorption processes, organic processes, Processes that
use: (pozzolana, fly ash, lime and Portland cement), Macro-encapsulation, Micro-encapsulation).
Hence in this paper the strength of the dumped waste and the CBR values after
stabilization with fly ash are studied.
WASTE SAMPLECOLLECTION AND TESTING METHODOLOGY
Illegal Dumping of municipal solid waste (dumped waste)
Illegal dumping of MSW is found next to Mavallipura landfill site area. This waste was
brought in by the municipal and contract Lorries before the landfill was in operation.
Fig. 2.Illegal dumping of municipal solid waste (Dumped waste)
This waste includes newspaper, junk mail, today’s meal scraps, pieces of bread, roti,
waste rice, raked leaves, dust grass clippings, broken furniture, abandoned materials, animal
manure, sewage sludge, industrial refuse or street sweepings etc. and this waste was dumped in
the open site, for the past 10 years in the form of a heap (of approximately 2.5m wide and 2m
height). The waste was found mixed with the local soil around due to many reasons such as
wind, disturbance by animals, etc. From this heap sufficient quantity of Dumped waste is
collected and kept in closed bags and carried to the laboratory for testing.

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Fly ash characteristics
The Fly ash that has been used in this present study was collected from the Raichur
Thermal Power plant which is in Raichur district of Karnataka state, India. The properties of Fly
ash are mentioned below in Table 2.
Table 2: Physical properties of Fly ash
Properties Fly ash
Colour Ash colour
Specific gravity 2.01
Liquid limit (%) 32
Plastic limit (%) Non-Plastic
Plasticity index (%) Non-Plastic
OMC (%) 22%
MDD (kN/m3
) 12.46
TESTING METHODOLOGY
Direct shear
In many geotechnical engineering problems the value of the angle of internal friction and
cohesion of the soil involved are required for the design. Direct shear test is used to predict these
parameters quickly. The direct shear device is used to determine failure envelopes for soils.
Sample preparation: The mass (M) of the wet sample (Dumped waste) at the required moisture
content (w) to give the desired density (d) shall be calculated. A batch of sample thoroughly by
mixed with 20% fly ash and water to give the required water content. Pour the weighed amount
of sample in the direct shear mould and kept it for 7 days curing. After curing the sample the
testing was done on until the specimen fails or at arrival of shear displacement of approximately
20 percent of the specimen length. Three tests are conducted at different normal loads. Tests
were performed in accordance with IS: 2720 (Part 13):1986.
California Bearing Ratio (CBR)
California Bearing Ratio (CBR) test is a compressive nature penetration test. This test is an
empirical test first developed in California, USA, for estimating the bearing value of highway
sub-bases and sub grades. The test is specifically used to determine the mechanical strength as
well as the potential strength of road sub grades and base courses materials including the
recycled material generally used for road and airfield pavements. CBR value is a percentage
comparison with the standard crushed rock from California and thus this test is a comparison
test. The CBR test was conducted as according to IS: 2720 Part 16 (1997).
Sample Preparation: The mass (M) of the wet sample (Dumped waste) at the required moisture
content (w) to give the desired density (d) shall be calculated. A batch of sample is thoroughly
by mixed with 20% fly ash and water to give the required water content. Then mould is fixed on
the base plate. Place the filter paper inside. Pour the weighed amount of sample in the mould.
Sample is tamped by the steel rod during the process of pouring and makes the top surface

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-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
0.0 2.0 4.0 6.0 8.0 10.0 12.0
VolumetricStrain(%)
Shear Strain (%)
Norma stress:50kPa
Normalstress:100kPa
Normalstress:150kPa
0.00
20.00
40.00
60.00
80.00
100.00
120.00
0.00 2.00 4.00 6.00 8.00 10.00 12.00
ShearStress(kPa)
Shear Strain (%)
Normal Stress=50kPa
Normal Stress=100Kpa
Normal Stress=150kPa
roughly level. Then a filter paper was placed on the top of the sample and spacer disc was
inserted. Mould has to be kept for 7 days curing. After curing, mould is kept in the testing
machine with the base plate in position and the top surface exposed. Plunger shall be kept under
a load of about 4kg so that full contact is ensured between the surface of the specimen and the
plunger. Stress and strain dial gauges are set to initial zero-reading. Load is applied to the
penetration plunger at the rate of penetration equal to 1.25mm per minute. The maximum load
and penetration is recorded for a penetration of less than 12.5mm. California Bearing Ratio test
was carried out as per IS: 2720 (Part 16):1986 procedure.
RESULTS AND DISCUSSION
Strength of Dumped waste with 20% flyash by Direct shear tests
Fig 4 shows the typical shear strain versus shear stress response under different normal stresses
for Dumped waste with 20% fly ash. Normal stress versus shear stress at 10% deformation was
plotted and the shear strength parameters were calculated based on the Mohr-Coulomb failure
criteria. Based on the analysis of the data, friction angle is 44°and no cohesion. A summary of
the dumped waste with 20% fly ash results is presented in Table 3.
Fig. 3. Shear stress vs. shear strain for Dumped waste with 20% fly ash
Fig. 4.Volumetric strain vs. Shear strain for Dumped waste with 20% fly ash

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Fig.5 shows the volumetric strain versus shear strain for Dumped waste with 20% fly ash mix.
From this graph we can observe initially sample get compressed and then sample starts swelling
(dilatation) for normal stress of 50 kPa hence dilatancy angle found to be 26.35° for 100kPa and
150kPa dilatation was not observed.
Table 3: Direct shear test results for Dumped waste with 20% fly ash mix
Normal stress
(kPa)
Peak shear stress
(kPa)
Φ
(Degrees)
50 32.9
44100 73.67
150 108.80
CBR Values of Dumped waste after stabilization with Fly Ash
Table.4 shows the comparison results of CBR test for waste without fly ash and 20% fly
ash.From fig 6 & 7 show the load versus penetration for Dumped waste without Flyash and with
20% Fly ash. The CBR value of 5mm penetration is found to be 1.2%.
Fig. 5. Load vs. Penetration for Dumped waste without fly ash
Fig. 6. Load vs. Penetration for Dumped waste with 20 % fly ash

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Table 4: Comparison of CBR test results for Dumped waste
Dumped waste
Sample
CBR value of 5mm
penetration
Waste +20% Flyash 1.2
Without stabilization 0.6
CONCLUSION
Based on the tests conducted on waste samples collected from dump site the following typical
values are obtained:
 It was found that addition of 20% of Fly ash improves the shear strength particularly due
to increase in coefficient internal friction angle without increasing cohesion intercept.
 The strength is still not sufficient and there is need to use higher amount of fly ash to
effectively stabilize the dumped waste.
 CBR value of the stabilized waste dump is 1.2 % as against CBR of subgrade soil of 4%.
With higher amounts of fly ash the waste dumps are promising for construction of proper
pavements.
REFERENCE:
 Bookter, T.J., and Ham, R.K., (1982). “Stabilization of solid waste in landfills,” Journal
of Environmental Engineering, vol.108, No.6, pp 1089–1100.
 Kogbara, Reginald B., Abir Al-Tabbaa, Yaolin Yi, and Julia A. Stegemann. "Cement–fly
ash stabilisation/solidification of contaminated soil: Performance properties and initiation
of operating envelopes." Applied Geochemistry 33 (2013): 64-75.
 IS: 2720 (Part 13)–1997. “Methods of test for soils,”Direct shear test. Bureau of Indian
Standards.
 IS: 2720 (Part 16)-1997. “Methods of test for soils,” California Bearing Ratio Test of
Soils. Bureau of Indian Standards.
 Malviya, Rachana, and RubinaChaudhary. "Factors affecting hazardous waste
solidification/stabilization: a review." Journal of Hazardous Materials 137, no. 1 (2006):
267-276.
 Naveen.B.P., Sivapullaiah.P.V.,Sitharam.T.G., " Disposal options for solid waste of
Bangalore city based on its characteristics", IJEWM, Vol.12,No.1,2013,pp77-88.
 Naveen.B.P. Sitharam.T.G., Sivapullaiah.P.V. “Evaluating the Dynamic Characteristics
of Municipal Solid Waste for Geotechnical Purpose”, Current Advances in Civil
Engineering, Vol.2, No.1, Jan.2014, pp.28-34.