A LABORATORY STUDY ON THE
UTILIZATION OF GBFS AND FLY ASH
TO STABILIZE THE EXPANSIVE SOIL
FOR SUBGRADE EMBANKMENTS
Koteswara Rao. D Venkatesh Ganja & Venkatesh Jagarlamudi Professor Graduate Students – 2012
Department of Civil Engineering University College of Engineering
JNTUK KAKINADA KAKINADA- 533 003, A.P, INDIA
Email: [email protected]
ABSTRACT
The problems with expansive soils have been recorded all over the world. In monsoon they imbibe water and swell and in summer they shrink on evaporation of water there from. Because of this alternative swelling and shrinkage lightly loaded civil engineering structures like residential buildings, pavements and canal linings are severely damaged. It is, therefore, necessary to mitigate the problems posed by expansive soils and prevent cracking of structures. Many innovative foundation techniques have been devised as a solution to the problem of expansive soils. The chief among them are sand cushion technique, cohesive non-swelling (CNS) layer technique and under reamed piles. Stabilization of expansive clays with various additives has also attained lot of success. The various additives used for stabilizing expansive soils are lime, calcium chloride, fly ash, GBFS, gypsum, rice husk ash and others. Experiments were done to find out all characteristics of these materials and the mix of the stratified embankment materials. The fly ash, through its pozzolanic activity gave an improved strength and the cohesive soil gave enough cohesion for slope stability and to resist erosion. The use of GBFS in the mix ensured higher strengths.
KEY WORDS: Fly ash, GBFS, OMC, MDD, CBR
1.0 INTRODUCTION
The volume changes in swelling soils are the cause of many problems in structures that come into their contact or constructed out of them.The black cotton soils of India have liquid limit values ranging from 50 to 100 per cent, plasticity index ranging from 20 to 65 % and shrinkage limit from 9 to 14 %. The comprehensive review of literature shows that a considerable amount of work related for the determination of deformation characteristics and strength characteristics of expansive soil worldwide. From various contributions, the investigations on strength characteristics of expansive soil conducted by S.Narasimharao et.al (1987,1996), Sridharan et.al (1989), Mathew et.al(1997), G.Raja Sekaran et.al(2002) and Ali.M.A. Abd-Allah(2009) are worthy of note. Improving the strength of soil by stabilization technique was performed by Supakji Nontananandh et.al(2004) and Can Burak Sisman and Erhan Gezer(2011). The effect of electrolytes on soft soils were explained by Sivanna, G.S (1976);Anandakrishnan et.al (1966); Saha et.al (1991); Rao, M.S et.al(1992);Sivapullaiah, P.V. et al (1994); Bansal et.al(1996); S. Narasimha Rao et.al(1996); Appamma, P.,(1998); Chandrashekar et.al (1999);G. Rajasekaran et.al (2000);J. Chu et.al (2002);Matchala Suneel et.al (2008). The effect of steel industrial wastes on soft soils were presented by Ashwani Kumar et.al (1998); Bhadra, T. K et.al (2002); Dr. D. D. Higgins (2005); Koteswara Rao (2006,2011);
1.1 OBJECTIVE
1.1.1 GENERAL
1.1.2 GRANULATED BLAST FURNACE SLAG (GBFS)
GBFS is produced when molten slag in the temperature range of 12500c and 15000c from the blast furnace is chilled rapidly by a water jet resulting in vesicular, vitreous material of predominantly coarse sand particles. GBFS has an ability to hydrate in the presence of water to more stable compounds. It, is therefore, seems to have a great potential for use as a binder for stabilization of road bases and sub bases. In road construction almost all countries use blast furnace slag to replace natural aggregates, either for blanket courses, bases or sub bases. In order to develop suitable specifications for using granulated slag in road sub base, detailed laboratory investigations were undertaken, in which GBFS in different proportions of locally available soil and fly ash were mixed and subjected to different tests to study the atterberg limits and strength characteristics of the various mixes.
1.1.3 AIR COOLED SLAG
Air cooled blast furnace slag is produced by putting the molten slag into a pit where it is allowed to cool slowly in open air. Crystallization takes place slowly in open air. Crystallization takes place resulting in materials, like, a fine- grained igneous rock. Because of its similarity to igneous rocks, it has found extensive use as concrete aggregate, road surfacing stone and road base course material. When air cooled blast furnace slag is crushed and screened, its physical properties make it particularly suitably as an aggregate, both coated and uncoated. In order to replace it in place of road aggregate, it is required to be hard, durable and tough.
1.1.4 FLY ASH
Power generation is the most vulnerable criterion of modern civilization where thermal process takes lead in comparison with hydro-electricity and others, owing to its easiness and availability of main ingredient that is coal. Nearly 70% of India's total installed power generation capacity is 'thermal' of which coal based generation is about 90%. But at the same time, disposal of huge quantity of fly ash generated from the power plants is a burning problem. This is detrimental to animal and plant life, since it pollutes the environment as well as it requires large area for its disposal, when availability of land is getting scarce day by day. Most of the plants now are facing shortage of dumping space for these waste materials. According to report of concerned authority, the accumulated fly ash in 2010 over the country was about 110 Million tonnes which is expected to be 140 Million tonnes by the year 2020. This necessitates effective utilization of this accumulated fly ash is being felt by the engineers and scientists. Utilization in the field of Civil Engineering extends ample scope for consuming bulk volume efficiently and economically.
Fly ash in a moist but unsaturated condition displays an apparent cohesion due to the tension of the retained capillary water but this cannot be relied upon for long term stability analysis and concluded that the strength property of major interest is angle of shearing resistance. Most of the fly ash shows an effective angle of shearing resistance of .about 32-35 degrees which is a typical value of coarse sand and it is highly permeable material. It possesses a varying colour from cream to dark brown or grey. It consists of 70% silica and alumina, a considerable amount of carbon and some crystalline matter (courtesy to VTPS, Vijayawada).
1.2 MATERIALS USED
Expansive soil
Fig.1 Plasticity Chart
Table 1: Properties of Expansive Soil
S. No. Property Value
1. Atterberg Limits:
Liquid Limit (%) Plastic Limit (%) Plasticity Index
47 22 25
2. Classification CI
3. Compaction Properties: Optimum Moisture Content (%) Maximum Dry Density kN / m3
19.5 1.49 4. Un-Soaked C.B.R. (%)
Soaked C.B.R. (%)
8.28 0.95 5. Specific Gravity
Fee Swell Index (%)
2.62 160 6. At O.M.C Condition:
Cohesion kN / m2 Angle of Internal Friction(O0 ) Bulk density kN / m3
71 6 19.4 7. At fully saturated Condition:
Critical angle of internal friction 1 (00) Critical cohesion c 1 kN / m 2
0 55
GBFS
Table 2: Physical Properties of GBFS
Sl.No. Property Value
1. Grain Size Distribution Poorly graded sand
2. Atterberg Limits NP
3. Compaction Properties: Optimum Moisture Content (%) Maximum Dry Density kN / m3
12.80 14.20 4. Un-Soaked C.B.R. (%)
Soaked C.B.R. (%)
12.80 11.50
5. Specific Gravity 2.52
6. Cohesion kN / m2 Angle of Internal Friction(O0 ) Bulk density kN / m3
0.00 35 16.10 Fly Ash
Fly ash was used in this study was collected from VTPS, Vijayawada, India.
Table 3: Physical Properties of Flyash
S. No. Property Value
1. Grain Size Distribution: Gravel (%) Sand (%) Silt (%) Clay (%)
---- 85 11 04
2. Atterberg Limits: NP
3. Compaction Properties: Optimum Moisture Content (%) Maximum Dry Density kN / m3
20.7 13.5 4. Un-Soaked C.B.R. (%)
Soaked C.B.R. (%)
5.50 3.15
5. Specific Gravity 2.1
6. At O.M.C Condition: Cohesion kN / m2 Angle of Internal Friction(O0 ) Bulk density kN / m3
8.00 31 16.29 7 At fully saturated Condition:
Critical angle of internal friction 1 (00) Critical cohesion c 1 kN / m 2
18 11.00
1.3 DAMAGES CAUSED BY EXPANSIVE SOILS ON PAVEMENTS AND EMBANKMENTS
1.4 STABILIZATION OF EXPANSIVE SOILS
Soil Replacement
Remove expansive soil entirely or to a considerable depth and replace with non-expansive soil (Zeitlen,1969; Chaturvedi, 1977; Ordemir et al.., 1977; Snethan et al., 1979; Chen, 1988). Generally the expansive soil extended to greater depths economically allow complete removal and replacement (Nelson, 1991). This method can be adopted only when expansive soil extends to a shallow depth and no expansive soil is available in abundance in the vicinity of construction.
Surcharge Loading
The expansive soil is loaded with a pressure to counteract swelling. This method is generally applicable only for soils with low and moderate swelling pressures where some heave can be tolerated viz., Secondary Highway Projects (Nelson, 1991). Chen (1988) claimed that at a relatively shallow depth beneath the structure, the intensity of added stress is small and swelling may occur below this level.
Heat Treatment
Russians have developed thermal stabilization technique to stabilize the expansive clays. This consists of blowing preheated air under pressure through boreholes. Uppal (1986) reported that the plasticity of soil decreases as temperature increases until 500°c and soil become non-plastic, but the effective depth of burning with mobile furnace is hardly 2.5 inches and consequently the technique is uneconomical.
Moisture Control
The magnitude of damage caused by expansive soils is controlled by wettest and driest moisture content profiles and is altered with removal or replacement of soil moisture (Picornell and Lytton, 1987). Steinberg, 1992; Evans 1999; Marienfeld and Baker, 1999 stated that moisture barriers could be successfully used in many cases to control movements generated from expansive soil sub-grade. Chen (1988) stated that these control measures will only delay the process of moisture migration and il1 the course of time the soil gets totally saturated.
Chemical Stabilization
Petry and Armstrong (1989) claim that chemical stabilization of expansive clays consists of changing the physical and chemical environment with in and surrounding the clay particles whereby the clay require less water to satisfy the static imbalance and making it difficult for water that moves into and out of the system. The most active days are those with sodium cations in exchange complex and probably the most effective chemical stabilization of expansive soils occur when sodium ions are replaced by divalent or trivalent cations. Hundreds of chemicals have been tried to alter the characteristics of day minerals; for example ion exchange by the addition of divalent or trivalent salts, cation fixation in expanding lattice clays with potassium and water proofing with asphalt have all been attempted.
Cohesive Non-swelling (CNS) layer method
According to Katti (1978), cohesive forces develop up to a depth of 1.0 m to 1.2 m with saturation of expansive soil, which help to counter heave in the soil beneath even through the soil within the zone itself swells. The surface electrical charge of clay particle produces adsorbed water bonds and develops cohesion, resulting in creating an effective overburden pressure. The top layer of expansive soil is removed up to a depth of 1m and replaced by cohesive non-swelling soil (CNS) layer, which was saturated later. A CNS layer creates an environment similar to that, which prevails within a depth of 1m in expansive soil with equivalent cohesion to counter heave. Gravel is a good example of CNS material. Katti's specifications for a CNS material are hard. The cohesive soil upon saturation is rendered soft and may cause failure of footing. So Katti (1996) recommended the use of a mechanically stabilized mix (MSM) to be placed on the top of the CNS cushion to make soil strong enough to bear the load. The experimental result on the soil is given below.
1.5 EXPERIMENTATION
Proctor Compaction Tests
in increments of 5 % each for the first layer and GBFS was mixed with fly ash in increments of 5% each for the second layer. Then after finding out the optimum of fly ash needed we added expansive soil in increments of 5% each to find out the mix that qualifies the MOST specifications.
Direct Shear Tests
Direct shear tests were carried out in the laboratory using a standard direct shear testing machine as per the IS code. This helped us to understand how the C and ɸ values of the mix change when different a proportion of the mix is taken. For this soil was added in increments of 5% each.
CBR Tests
CBR tests were carried out to find out the CBR values of the mix and to find out the mix that satisfies the MOST specification for choosing the mix. The tests were carried out in standard equipment as per IS code. The results and the discussion of the tests will follow this chapter.
Atterberg Limits
Atterberg limits of the materials were found out to find out the index properties of fine grained soil. Liquid limit, plastic limit, plasticity index, and specific gravity and were found out.
1.6 RESULTS AND DISCUSSIONS
To find the optimum percentages of fly ash with expansive soil for lower layer, optimum amount of flyash and expansive soil with GBFS for upper layer direct shear tests and CBR tests are conducted by using different proportions flyash – soil and soil – flyash – GBFS.
Fig. 2 Layers Showing Subgrade and Embankment with their Properties
1.5.1 Proctor Compaction Test Results Of Treated Soil Used For Embankment
The table 6 shows the OMC and MDD results of treated soil with different proportions of flyash.
Table 6: Properties of C.I. Soil with Fly ash as an Admixture
S. No
Property Type of Mix
C. I. Soil CI+3%FA CI+4%FA CI+5%FA CI+6%FA CI+8%FA CI+10%FA
1. OMC (%)
MDD(g/cc)
19.50
1.462
20.22
1.480
20.96
1.520
22.51
1.590
24.10
1.560
25.60
1.48
25.65
1.5.2 CBR Test Results of Treated Soil Used For Embankment
The table 7 presents the CBR results of treated soil with different proportions of flyash.
Table 7: CBR Results of C.I. Soil in % Variation of Fly ash
S. No.
Property Type of Mix
C.I. Soil CI+5%FA CI+10%FA CI+15%FA CI+20%FA CI+25%FA CI+30%FA
1. Soaked
CBR (%) 1.50 1.80 2.28 3.24 4.40 3.50 2.00
It was observed that the soaked CBR increased with increasing percentage of flyash in the mix up to 20 % and started decreasing after that. Therefore the optimum flyash content in the mix is 20 %.
As per IRC: 37-1984 guidelines for design of flexible pavements the minimum soaked CBR value required for 1st layer is 3. The flyash content of 20 to 30 percent were found to satisfy this criterion.
1.5.3 Index And Engineering Properties of the Mix (Soil + 20% FA)
From proctor compaction test, mixes with 5to 20 percent of flyash were able to meet the IRC criteria for MDD whereas the mixes having 20 to 30 percent of flyash meet the IRC criteria for CBR. Therefore the best mix was selected as 20% of flyash with soil.
Direct shear tests were conducted on the mix having optimum % of flyash with soil .As compared to pure expansive soil it was found that the Cohesion (C) has decreased while the critical angle of internal friction has increased.
CI soil
CI + 3% FA CI + 4%FA
CI + 5%FA
CI + 6%FA
CI + 8%FA
CI + 10%FA
1.3 1.4 1.5 1.6
0 2 4 6 8 10 12
M
.D.
D i
n
(g/
cc
)
CI SOIL WITH FLY ASH
Fig
3.
Variation
of
MDD
with
%
change
in
fly
ash
in
CI
SOIL
+
FA
mix
0, 1.5 5, 1.8
10, 2.28 15, 3.24
20, 4.4
25, 3.5
30, 2
0 0.51 1.52 2.53 3.54 4.55
0 10 20 30 40
SO
A
K
ED
CB
R
VALUE
(%)
CI SOIL WITH FLY ASH
Fig
4
.Variation
of
Soaked
CBR
Value
with
%
Variation
of
Fly
ash
in
Table 8: Properties of CI Soil + 20% Flyash
S. No. Property Value
1. Atterberg Limits:
Liquid Limit (%) Plastic Limit (%) Plasticity Index
33 21 12
2. Compaction Properties:
Optimum Moisture Content (%) Maximum Dry Density kN / m3
25.65 1.550 3. Un-Soaked C.B.R. (%)
Soaked C.B.R. (%)
12 4.4
4. Specific Gravity 2.64
5. At O.M.C Condition:
Cohesion kN / m2 Angle of Internal Friction(O0 ) Bulk density kN / m3
32 13 19.46
6. At fully saturated Condition:
Critical angle of internal friction 1 (00) Critical cohesion c 1 kN / m 2
5 31
1.5.4 Compaction Test Results of GBFS With % Variation of Fly Ash
The compaction test results of GBFS with % variation of fly ash are presented in the table 9.
Table 9: Compaction Properties of GBFS with % Variation of Fly ash for Subgrade
S. No.
Property Type of Mix
GBFS GBFS +
2% FA
GBFS + 3% FA
GBFS + 4% FA
GBFS + 5% FA
GBFS+ 6%FA
GBFS+ 7%FA
1. OMC (%) MDD(kN/m2)
10.00 1.43
10.20 1.45
10.30 1.49
10.40 1.54
10.60 1.58
11.00 1.52
Flyash was used to improve the cementenious property of GBFS by its pozzolanic action. From the proctor compaction test it was found that the MDD was maximum for 5% flyash.
1.5.5 CBR Test Results of GBFS with % Variation of Fly Ash Used for Subgrade
The soaked CBR values are presented in the table 10 and it was observed that for an optimum of 5% F.A, the CBR value of the treated GBFS was maximum.
Table 10: Properties of G.B.F.S with fly ash as admixture
GBFS
GBFS + 3% FA
GBFS + 4% FA
GBFS + 5% FA
GBFS + 6% FA
GBFS + 7% FA
7, 1.5
1.3 1.4 1.5 1.6
0 1 2 3 4 5 6 7 8
M
.D.
D i
n
(g/
cc
)
GBFS WITH FLY ASH
Fig
5
.
Variation
in
MDD
of
GBFS
with
%
Variation
of
Fly
ash
S. No
Property
Type of Mix GBFS GBFS+
2%FA
GBFS+ 4%FA
GBFS+ 5%FA
GBFS + 6%FA
GBFS + 8%FA
1 Soaked
1.5.6 Properties of 5% FA + 95% GBFS Mix
The table 11 presents the properties of 95% GBFS + 5% FA mix.
Table 11. Properties of G.B.F.S + 5% Flyash
S. No. Property GBFS+5%FA
1 Compaction Properties: Optimum Moisture Content (%) Maximum Dry Density g/cc
10.6 1.58 2 Un-Soaked C.B.R. (%)
Soaked C.B.R. (%)
20.14 18.14 3 Specific Gravity
Fee Swell Index (%)
2.54 …. 4 At O.M.C Condition:
Cohesion kN / m2 Angle of Internal Friction(O0 ) Bulk density kN / m3
6.00 32 16.3
The mix of 5 % FA and 95 % GBFS is able to fulfill the IRC criteria of MDD and soaked CBR. But the direct shear test data shows that we cannot use this mix in sub grade construction as the cohesion value is very less (6.0 kN/m2). This low value of cohesion makes us think of using another admixture in the mix which can improve the cohesion value so that it can give a stable slope and has sufficient erosion resistance. Here we can adopt a feasible solution of adding cohesive soil to improve the cohesion. Therefore expansive soil offers a better solution for this demanding problem.
1.5.7 Compaction Properties of G.B.F.S +5% Fly Ash Mix With % Variation of C I Soil For Subgrade
The table 12 presents the compaction properties of G.B.F.S +5% Fly Ash Mix With % Variation of CI Soil For Subgrade
0, 10
2, 12
4, 16
5, 18.14
6, 17.23
8, 13
0 4 8 12 16 20
0 1 2 3 4 5 6 7 8 9
SO
A
K
ED
CB
R
(%)
GBFS WITH FLY ASH
Fig
6.
variation
in
Soaked
CBR
Values
of
GBFS
with
%
Variation
of
Table 12: Properties of G.B.F.S +5% Fly ash Mix with % Variation of CI Soil
S.
No Property
Type of Mix GBFS+
5% F A
GBFS +5%FA +5%CI GBFS +5%FA +10%CI GBFS +5%FA +15%CI GBFS +5%FA +20%CI GBFS +5%FA +25%CI
1. OMC (%)
MDD(g/cc) 10.60 1.580 12.60 1.62 15.32 1.68 22.14 1.779 19.00 1.760 18.60 1.720
The optimum MDD of GBFS + 5% FA+ 15% soil was 1.779 g/cc at OMC of 22.14%, which is greater than the required MDD (1.750 g/cc) as per IRC: 37-1984.
1.5.8 CBR Properties of G.B.F.S +5% Fly Ash Mix With % Variation of C I Soil For Subgrade
Table 13 presents the CBR results of GBFS + 5% FA mixes with different proportions of CI soil
Table 13: CBR Values of G.B.F.S +5% Fly Ash Mix with % Variation of C I Soil
It was observed that the soaked CBR value of G.B.F.S +5% Fly Ash Mix was increased with increasing percentage of CI soil up to 15 % and then started decreasing. Therefore the optimum CI soil content in the mix is 15 %. As per IRC: 37-1984, the guidelines for design of flexible pavement the minimum soaked CBR value required for subgrade is 10%.
0, 1.58
5, 1.62
10, 1.68
15, 1.779
20, 1.74
25, 1.72
1.5 1.55 1.6 1.65 1.7 1.75 1.8 1.85
0 5 10 15 20 25
M.D.D in g/ cc GBFS + 5% FA + CI SOIL
Fig
7.
Variation
of
MDD
with
%
change
of
FA
in
GBFS
+
5%
FA
+
CI
SOIL
mix
S
.No. Property
Type of Mix GBFS+5% F A GBFS+5%FA +5%CI GBFS+5%FA +10%CI GBFS+5%FA +15%CI GBFS +5%FA +20%CI GBFS +5%FA +25%CI 1. Soaked
1.5.9 DIRECT SHEAR TEST
Table 14 presents the Cohesion (C) and angle of internal friction (ɸ) of “GBFS + 5% FA+ 15% Soil” mix.
Table 14: C and ɸ of “GBFS + 5% FA+ 15% soil” mix
% of CI soil C kN/m2 ɸ O
0.00 6.00 32.00 5.00 32.00 31.43 10.00 43.00 30.96 15.00 49.00 25.56 20.00 59.00 19.32 25.00 67.00 16.23
As it was observed, there was a considerable improvement in the cohesion value of the mix when 15% cohesive soil was added. The cohesion value had been increased from 6kN/m2 to 49kN/m2 with the addition of 15 % of CI soil with GBFS +5% FA mix.
CONCLUSIONS
The following conclusions are drawn based on the laboratory studies carried out in this investigation.
1. It was observed that the 20% flyash + 80 % expansive soil mix gives optimum CBR value for the first layer of the embankment.
2. It was observed from the compaction test results that the CBR value was optimum for the 5% fly ash + 15% expansive soil + 80 % GBFS mix and it can be used for the pavement sub grade.
3. It was observed that the CBR value was optimum by the addition of 5 % flyash with the GBFS.
4. It was noticed that the cohesion of the 5 % flyash + 80 % GBFS mix has been increased by 716% with the addition of 15 % expansive soil.
5. It was noticed that the angle of internal friction of the 5 % flyash + 80 % GBFS mix has been decreased by 20% with the addition of 15 % expansive soil.
1.6 REFERENCES
[1] Chandrashekar, B.P., Prasada Raju, G.V.R (1999), Relative Performance of Lime and Calcium Chloride on Properties on Properties of Expansive Soil For Pavement Subgrades, Proc. Of IGC-99, Calcutta, 1999, pp 279-282.
[2] D. Koteswara Rao (2004), The performance studies on Geo-grid as reinforcement in the flexible pavement construction, IGC-2004, pp 457-460.
[3] Desai, I.D. and Oza, B.N (1977), Influence of Anhydrous Calcium Chloride on the Shear Strength of Expansive Soil, Proc. of the 1st
National Symposium on Expansive Soils, HBTI-Kanpur, India, 1977, pp. 4-1 to 4-5.
[4] G.V.R. Prasada Raju (2001), Evaluation of Flexible Pavement Performance with Reinforcement and Chemical Stabilization of Expansive Soil Subgrade, a Ph.D. thesis , Kakathiya University, Warangal,(A.P, INDIA).
[5] Gopal Ranjan, A.J.R. Rao, a text book on “Fundamentals of soil mechanics.” [6] IS: 2720 part- 5 (1970): Determination of Liquid limit and Plastic limit.
0, 10.3
5, 11.2
10, 13.3 15, 14
20, 12
25, 9.35
7 8 9 10 11 12 13 14 15
0 5 10 15 20 25 30
SO
A
K
ED
CB
R
(%)
(GBFS + 5% FA) WITH CI SOIL
Fig
8
.
CBR
Values
of
G.B.F.S
+5%
Fly
Ash
Mix
with
%
[7] IS: 2720 part- 6 (1972): Determination of Shrinkage limit.
[8] IS: 2720 Part-10 (1973): Determination of Unconfined compressive strength. [9] IS: 2720 part- 6 (1974): Determination of Dry density and Optimum moisture content. [10] IS: 2720 part- 4 (1975): Grain size analysis.
[11] IS: 2720 part-40 (1977): Determination of Free Swell Index. [12] IS: 2720 Part-16 (1979): Determination of California bearing ratio.
[13] Jaganatha Rao, P and Jai Bagwan, 2001. “ Fly ash as structural fill in highway embankments – a measure for geo-environmental hazard”. IGC, 14-16 December.
[14] Krishna Swamy,N.R and Santhosha Rao,N., 1995. “ Experimental studies on model embankments made of reinforced fly ash”. IGC, Vol. No. I.
[15] Praveen Kumar, Mehndiratta and Siddhartha Rokade, 2005. “ Use of reinforced fly ash in highway embankments”. Highway Research Bulletin, Vol.No.73.
[16] Raza, S.A. and Chandra, D., 1995. “ Strength of soil-fly ash mixtures with geo-textile reinforcement”. IGC-95, Vol. No. I. [17] Sharma, R.K., 2005. “ Behaviour of reinforced soil under cyclic loading”. Highway Research Bulletin, Vol.No.73.
[18] Sikdar, P.K and Guru Vital, U.K., 2004. “ Economics of using fly ash in road construction “. Indian Highways, January 2004. [19] Sinha, U.N., Ghosh,A., Bhargave,S.N.,and Dalip Kumar, 1995. “ Geotechnical investigation of earth-fly ash embankment of fly ash
pond “. IGC, Vol. No. I.
