IGC. 50 th INDIAN GEOTECHNICAL CONFERENCE A NEW EPS BEADS BASED LIGHTWEIGHT GEOMATERIAL FOR BACKFILLING AND EMBANKMENT CONSTRUCTION

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1 50 th A NEW EPS BEADS BASED LIGHTWEIGHT GEOMATERIAL FOR BACKFILLING AND EMBANKMENT CONSTRUCTION Y. S. Golait 1, A. S. Patode 2 ABSTRACT Construction of embankments and backfilling behind retaining walls presents problems of settlement and stability; especially when this is required to be done on natural soft compressible soil deposits. Use of appropriately strong but lightweight material in such constructions can solve many such problems. Super lightweight type factory manufactured expanded polystyrene (EPS) geofoam blocks of standard sizes are being used in several countries (Norway, Netherlands, US, Japan, France, Germany, UK etc) since about Further development in this respect was a composite lightweight geomaterial made from soil + EPS beads + 10 to 15 % cement. Its use in many geo-constructions started from about However, this lightweight geomaterial technology has not yet found its place in geotechnical construction practice in our country. In order to make this technology more relevant, technically sound and cost effective in the present scenario in India, an effort is made to develop a new EPS beads based lightweight geomaterial (LWGM) of desired characteristics for its use in embankments and backfillings. The paper presents the investigations carried out in this respect and the outcome thereof. The proposed geomaterial has three main constituents viz. fly ash (FA), EPS beads (B) and cement (C). The fly ash is continuously produced in unimaginably huge quantity in our country from several thermal power plants. In absence of its timely and effective disposal it creates many environmental hazards. This fly ash forms the main constituent of the proposed geomaterial. The lightness of the material is accomplished by adding EPS beads in fly ash. A small quantity of cement is proposed to be used for appropriate strength development. An intensive laboratory investigation program was planned involving testing of 21 samples of composite material of different proportions of three constituents and under three curing periods of 7, 14 and 28 days. It was aimed to develop a composite material containing larger percentage of EPS beads and lesser quantity of cement. The trial mixing and testing revealed that the beads content should be 0.8% to 1.0% of the weight of fly ash and cement content of 6% to 10% in order 1 Professor Emeritus, PG Geotechnical Section, Ramdeobaba College of Engineering and Management, Nagpur-13, India, yadavgolait@gmail.com 2 Ex. PG (Geotech. Engg.) Student, Ramdeobaba College of Engineering and Management, Nagpur-13, India, anilpatode@gmail.com

2 Dr. Y. S. Golait & A.S. Patode to arrive at the desired lightness while getting the compressive strength larger than that of commonly used traditional earth in embankment construction and backfilling. The test results of 21 samples of EPS beads based geomaterial are discussed with respect to variation in unit weight, stress-strain nature, variation in compressive strength, effect of curing period on strength development etc. The findings from the study are enlisted here under: a. The lightweight geomaterial (LWGM) evolved from the study by using fly ash and expanded polystyrene beads has high potential for its use in several geotechnical constructions in infrastructure development works in India. b. The composite material of required lightness and strength can be formed by adjusting EPS beads (B) content from 0.8% to 1.0% of weight of fly ash (FA). However, for appropriate strength development 6 to 10% cement (by weight) is needed. c. The LWGM having composition C:B:FA = 1:8:10 (by volume) is considered appropriate for embankment construction on soft compressible grounds and for backfilling. This suggested material exhibits unit weights 1.07 and 0.90 g/cc under soaked and dry states respectively. Its strength properties are found as c = 2.45kg/cm 2, ϕ = 21 and UCS = kg/cm 2. d. As compared to traditional coarse grained murum type earth commonly used in embankment construction and backfilling, the suggested LWGM is 50% light and 16.5 times strong. e. The LWGM developed from the study can be used in the form of blocks of any size pre-casted and cured at casting yard near site or as wet mix to be placed in bulk for the desired construction job. f. Embankments with very steep slopes can be formed by using LWGM. This results in substantial saving of land area occupied by embankment. Besides, the volume of embankment material is significantly reduced. Keywords: Lightweight geomaterial, EPS beads, Fly ash, embankments, backfillings.

3 50 th A NEW EPS BEADS BASED LIGHTWEIGHT FILL GEOMATERIAL FOR BACKFILLING AND EMBANKMENT CONSTRUCTION Dr. Y.S. Golait, Professor Emeritus (PG Geotechnical), RCOEM Nagpur 13 (India), A.S. Patode, Ex. PG (Geotechnical) Student, RCOEM Nagpur 13 (India), anilpatode@gmail.com ABSTRACT: Construction of embankment and backfilling behind retaining walls presents problems of settlement and stability, especially when this is required to be done on natural soft compressible soil deposits. Use of appropriately strong but lightweight material can solve many such problems. The studies presented in the paper pertain to development of a new lightweight geomaterial (LWGM) using fly ash (FA) and EPS beads (B) with addition of a small quantity of cement (C). Elaborate laboratory investigation on total 21 samples of different compositions enabled property characterization with respect to unit weights, compressive strengths, stress-strain nature etc. The LWGM of composition C:B:FA = 1:8:10 (by volume) is suggested for backfilling and embankment construction. This geomaterial is sufficiently light with its unit weight of about 1.0 g/cc; and highly strong having unconfined compressive strength of nearly 10kg/cm 2. The proposed new LWGM is considered to be highly appropriate and useful in the present Indian scenario where disposal and effective utilization of fly ash is a national concern. INTRODUCTION Expanded Polystyrene (EPS) is a super lightweight synthetic cellular material that was invented in This rigid plastic foam type material is being used in geotechnical constructions since 1960 s when a product category Geofoam [1]. The EPS geofoam is available in the form of factory manufactured lightweight large size blocks of specific dimensions. Since about 1990 s it is utilised extensively in several countries, especially Norway, Netherlands, US, Japan, France, Germany, UK, Malaysia etc. Its bulk unit weight (which varies from kg/m 3 ) is roughly a hundredth of that for conventional earth materials. This imparts beneficial effects in geo-constructions like slope stabilization, embankment construction on soft compressible grounds, backfilling behind retaining walls and in trenches of buried conduits. Besides, the geofoam is sufficiently strong to support heavy loads of motor vehicles, trains, airplanes, abutments of bridges etc if properly designed. It also has good sound and vibration absorption capacity [2, 3, 4]. Lin et al in 2010 have reported that the use of geofoam blocks in infrastructure projects suffers from some disadvantages viz. (i) EPS geofoam blocks cannot be formed at the site, hence its transportation from factory to site is necessary, (ii) these factory manufactured blocks are usually of specific size and shape, therefore it is not possible to use them to fill in irregular volumes/shapes, and (iii) the basic properties of EPS geofoam blocks cannot be modified to suit the site conditions or the requirements of the intended geotechnical structure [5]. Besides, construction with EPS geofoam blocks is usually costlier as compared to other methods of construction. In order to overcome the aforesaid limitations some alternatives have been suggested and investigated. One such viable alternative is the development of EPS beads based lightweight soil cement, in which a composite material of mixture of EPS beads, soil and cement is blended. Such lightweight material was first introduced in Japan in the 1980 s. This material

4 Dr. Y. S. Golait & A.S. Patode has been used in many geotechnical constructions [6]. Several experimental studies and numerical investigations on this material are reported by many researchers [6, 7, 8, 9, 10]. It is realized that the cement content to be used in such blended material is considerable i.e. upto about 15% in order to attain required strength. Yet another reality associated with the use of lightweight geomaterial in India is that neither EPS geofoam blocks nor EPS beads blended soil material is yet practiced in the country to any noticeable extent. In order to make this lightweight geomaterial technology more relevant, technically sound and cost effective in the present scenario in India, an effort is made to develop a new EPS beads based lightweight geomaterial (LWGM) of desired characteristics for its use in construction of embankments and backfilling behind retaining structures. The paper presents the investigation and the outcome thereof. REQUIREMENTS OF THE PROPOSED LWGM AND MATERIALS USED. The lightweight geomaterial (LWGM) to be developed is considered to satisfy the two main requirements for its advantageous use in embankment construction on soft grounds and for backfilling purposes. i. It should have superior strength as compared to that of conventional earth material usually used in practice. ii. The density, or in other words the bulk unit weight of proposed material has to be substantially less than that of the compacted or in-situ consolidated earth material, though it may not fall in the category of super lightweight material like EPS geofoam blocks. Besides these two main criteria, it is also desirable that the material can be prepared, blended and used at site in bulk filling form. Also it should be possible to form the well cured, strong blocks at suitable casting yards and then used at site by transporting them thereform. The reduction in unit weight is proposed to be achieved by using EPS beads which are easily available in India. Such beads are manufactured in our country at many places for their use especially for packaging products. While evolving the new LWGM, it was thought to replace the main constituent (i.e. soil) in the mixture by an appropriate, easily available and cheap material that is better than soil. In the present day context, fly ash is considered as the most desirable alternative. It is well known fact that tackling the problem of safe disposal and proper utilization of fly ash in various potential areas of construction activity is of supreme priority in our country. This by-product of coal combustion in thermal power plants is an excellent pozzolan containing significant amounts of silicon dioxide (SiO 2 ), aluminium oxide (Al 2 O 3 ), iron oxide (Fe 2 O 3 ), calcium oxide (CaO) and magnesium oxide (MgO). In view of nearly 65% power in India being generated through thermal power plants, the production of fly ash every year is in unimaginably enormous quantity. As per the Department of Science and Technology Report, 160 million tonnes of fly ash was produced in the year If this material is not suitably disposed off and properly utilized, it creates serious environmental effects. It is thus evidently a national service to search for various avenues for the effective utilization of fly ash in infrastructural development projects and works. The aforesaid considerations have weighed heavily in developing a lightweight geomaterial (LWGM) for its bulk utilization especially in embankment constructions and backfilling jobs. The criterion considered is to come out with such a material having unit weight of about 1g/c.c. and compressive strength of about 10 kg/cm 2. The materials actually used in this investigation are: (a) EPS Beads The bulk samples of EPS beads were obtained from M/s R.K. Industries whose plant is located near Nagpur (Maharashtra). Their product is extensively used in manufacturing of high quality geofoams and thermocol sheets that are supplied all over Vidarbha, Chhattisgarh, and South Madhya Pradesh. The spherical beads have diameter 2-4

5 50 th mm and the unit weight of beads in bulk form is 1.26 kg/cm 3 (1.26 x 10-3 g/cc). (b) Fly ash The fly ash used in the investigation was collected from Koradi Thermal Power Plant situated on the outskirts of Nagpur city. This fly ash belongs to class F category as per detailed property investigations done by Padade [11]. The relevant properties exhibited by the fly ash are given in Table 1. Table 1 Properties of fly ash from Koradi Thermal Power Plant [11] Particulars Property value Silt size particles 78% Sand size particles 15% Clay size particles 7% Uniformity coefficient, C u Standard Proctor Compaction -M D D 1.21 g/cc -O M C 24 % Specific gravity, G 2.15 Chemical composition -SiO 2 -Al 2 O 3 -Fe 2 O 3 -CaO % % 5.0 % 1.23 % Total loss on ignition 1.49 % (c) Cement Several trials in preliminary investigation have indicated that it is not possible to get the LWGM of desired unit weight and strength from the mixture of EPS beads and fly ash. It was therefore thought necessary to add cement in the mix to develop cementetious bonds in the fly ash matrix. An ordinary Portland cement of grade 43 was thus used in the investigation. It is thus aimed to develop the light weight geomaterial (LWGM) of desired properties by using the three material constituents viz. Fly ash (FA), EPS beads (B) and Cement (C). It is to be realised in this context that though the increase in the content of B leads to considerable reduction in unit weight of LWGM, it simultaneously results in strength reduction. This strength reduction is alleviated by cement. However, it is necessary and of prime importance to keep the cement content as low as possible to impart cost effectiveness to the developed LWGM. Probably the first ever and lone attempt so far on study of a LWGM using FA, B and C has been made by Padade [11] as a small part of his doctoral research work at Indian Institute of Technology Bombay under the guidance of Dr. J.N. Mandal. Mixes with B content varying from 0.5 to 2.5 % of FA and cement content varying between 10 and 20% of FA were investigated. The unit weight of the product was found to vary from to 1.32 g/cc and the compressive strength was between 1.58 and 32.9 kg/cm 2 [11, 12]. The authors of the paper are of the opinion that the LWGM with unit weight less than 1.0 g/cc will pose problem of floating when such mass gets submerged any time during the life of geostructures. Besides, the use of large quantity of cement as high as 15, 20 % etc will make the recommended LWGM unattractive for practical usage in view of high cost of cement. These considerations are given due weightage in development of LWGM in the present study. MIX COMPOSITIONS INVESTIGATED It was found from few trials that the use of beads content of 1.5% or more does not enable homogenous mixing of three constituents with water. Some quantity of beads always remained segregated from the wet mix. Hence the maximum beads content was kept limited to 1.3%. The cement content of minimum 6% and maximum 10% was finalised. It was also found from trials that moulding water content, expressed as ratio of weight of water to weight of fly ash, of 40 % and less does not enable uniform mixing of all constituents of mix. Similarly, water content of 50 % and above creates bleeding of thin slurry of fly ash plus cement from the mix during its light compaction. In view of these happenings, a molding water content of 45% was finalized for the preparation of all test samples. The main component (M) of the mix is fly ash. However, in one sample M composed of fly ash

6 Dr. Y. S. Golait & A.S. Patode (FA) and suitable soil (clayey silt of loam category) in 70:30 proportion. Total 21 samples of different compositions were investigated. Their composition and other particulars are given in Table 2. Table 2 Composition and particulars of test samples. Composition Molding Curing Sample (in %) W.C. period No. M B C (%) (days) 1 FA FA FA FA FA FA FA FA FA FA FA FA FA FA FA FA FA FA FA FA FA : Soil 70 : SPECIMEN PREPARATION AND LABORATORY TESTS The cylindrical test specimens were prepared in split moulds having 3.8cm diameter and 7.6cm height. For each specimen the pre-calculated required quantities of fly ash, EPS beads, cement and water were kept ready. Weighing operations were done using precision electronic weighing machine having accuracy of 0.01g. Initially, thorough dry mixing of fly ash and cement was done and then the calculated quantity of potable water was added in 2-3 stages. Simultaneously mixing by hand was continued to get homogenous slurry. EPS beads were added to this slurry and mixed thoroughly till a homogenous wet mix of all constituents was formed. The mix was then filled in the split mould in 3 layers by giving light tamping on each layer. After setting time of one day the test specimen was removed from the mould and kept in water tank for curing. The curing periods for various samples were as shown in Table 2. The specimen was taken out of water after curing and its dimensions and weight were recorded immediately. These observations enabled to find the soaked unit weight of cured specimen. The specimen was then air dried for couple of days and again it was weighed to get its dry unit weight. The specimen was transferred on unconfined compressive strength test machine operating at constant deformation rate of 1.25mm/min. Test was conducted during which axial load was measured from proving ring dial gauge reading and the axial shortening of specimen was found from reading of another dial gauge. This strength test enabled to get the stress-strain curve upto axial load little beyond the failure stage. TEST DATA, INTERPRETATION AND DISCUSSION The test results obtained from the laboratory investigation on 21 samples are given in Table 3. The results are discussed sequentially with respect to variation in unit weight, stress-strain nature, variation in compressive strength and the effect of curing period on strength etc. Unit Weight of LWGM It is seen that there is marginal difference in the unit weights under soaked and dry conditions. The

7 Dry unit weight ϒ (g/cc) Dry unit weight ϒ (g/cc) 50 th Table 3 Unit weight and strength test results Unconfined Strain Compressive Sample Unit Weight,ϒ at Strength, No. (g/cc) Failure, UCS (kg/cm 2 ε ) f (%) Soaked Dry dry unit weight exhibited by various mixes of the LWGM after 7 days of curing is of more relevance; and hence these values are considered for qualitative comparison. The effect of EPS beads content (B) on the unit weight (ϒ) of resultant LWGM is shown in Figure 1. Likewise, the effect of cement content (C) is represented in Figure 2. From the consideration of potential practical usage of the newly proposed LWGM in major infrastructure development works, it is considered that such material may have composition with B varying between 0.8% and 1.0% along with C variation from 6% to 10%. For these ranges the variations as shown in figure 1 and 2 are nearly linear. In general, ϒ decreases with content while it increases with increase in C content. The rates of variation in ϒ are calculated and given in Table C - 6% C - 8% C - 10% EPS beads content B (%) Fig. 1 Variation of dry unit weight with EPS beads content days curing 7 days curing B - 0.8% B - 0.9% B - 1.0% Cement content C (%) Fig. 2 Variation of dry unit weight with Cement content

8 Dr. Y. S. Golait & A.S. Patode Table 4: Rate of variation in ϒ with B and C Constant Parameter Rate of variation in ϒ with B and C C = 6% gm/cm 3 per 0.1% C = 8% gm/cm 3 per 0.1% C = 10% gm/cm 3 per 0.1% B = 0.8% gm/cm 3 per 1% increase in C B = 0.9% gm/cm 3 per 1% increase in C B = 1.0% gm/cm 3 per 1% increase in C In general, the LWGM may be considered to exhibit the dry and soaked unit weights as: 0.90 and 1.07 gm/cm 3 for B = 0.8% 0.85 and 0.97 gm/cm 3 for B = 0.9% 0.91 and 0.81 gm/cm 3 for B = 1.0% Stress-Strain Nature The stress-strain curves for all the samples were plotted. The typical curves for samples 1, 2 and 8 (i.e. mixes with 0.8% B and C content of 6%, 8% and 10%) are shown in figure 3. Similar nature was observed for almost all samples. It is seen that the stress-strain behavior of the LWGM is more of linear nature than the non-linear (or curved) type. The constant proportionality between stress and strain is evident almost upto failure stage of the material. The newly proposed EPS beads based LWGM is found to exhibit failure strain of about 2.5%, its range being 2.4 to 2.8%. Compressive Strength of the LWGM The values of unconfined compressive strength, UCS, are given in Table 3 and are graphically represented in Figures 4 and 5. These figures, as expected, clearly indicate that the compressive strength of the LWGM decreases with increasing beads content, while it increases with increase in cement content. The decrease in UCS takes place at uniform rate within B content of 0.8% to 1.0%. However, the UCS increases at higher rate upto cement content of 8% and then this rate is smaller beyond 8% cement content. It is thus indicative of desirability of keeping cement content upto 8% in practical application of this type of LWGM. Table 5 shows the rates of variation in UCS of the geomaterial. Axial stress σ kg/cm C - 6% C - 10% C - 8% Axial Strain ε (%) Fig. 3 Stress-strain curves for UCS tests for 7 days strength of LWGM Table 5 Rates of variation in UCS with increasing B and C contents Constant Rate of variation in UCS with B and Parameter C C = 6% 0.40 kg/cm 2 per 0.1% C = 8% 1.20 kg/cm 2 per 0.1% C = 10% 1.80 kg/cm 2 per 0.1% B = 0.8% 2.60 kg/cm 2 per 1% increase in C (C 8%) 0.80 kg/cm 2 per 1% increase in C (C > 8%) B = 0.9% 1.94 kg/cm 2 per 1% increase in C (C 8%) 0.73 kg/cm 2 per 1% increase in C (C > 8%) B = 1.0% 1.90 kg/cm 2 per 1% increase in C (C 8%) 0.10 kg/cm 2 per 1% increase in C (C > 8%)

9 50 th Compressive Strength (kg/cm2) UNconfined Compressive Strength (kg/cm2) Compressive Strength (kg/cm2) Fig. 4 Variation of UCS with Beads, B(%) days curing, dry strength EPS beads content B (%) 7 days curing, dry strength Cement content, C (%) Fig. 5 Variation of UCS with Cement, C(%) C - 6% C - 8% C - 10% B - 0.8% B - 0.9% B - 1.0% Effect of Curing Period on Strength Development The strength developed in 7 days of curing of the geomaterial is considered as the reference strength. Beyond 7 days the strength gain of LWGM with prolonged period of curing upto 28 days is found to be almost linear as shown in Figure 6. The geomaterial of fly ash and cement mixes (without EPS beads) also exhibited similar linear strength gain as depicted by lines (iii) and (iv) in the Fig. 6. It is seen that the LWGM of composition B = 0.8% and C = 8% (i.e. sample 2,3,4) the strength increase in 14.34% and 38.51% for curing period of 14 days and 28 days respectively. Similarly, for LWGM of composition B = 0.8% and C = 10% the respective values of strength gain are 12.54% and 45.68%. the corresponding samples without beads and with 8% cement the strength increased values are 6.32% and 24.47%; while those with 10% cement exhibited strength increases of 5.61% and 17.76%. The rates of strength gain per day beyond 7 days and upto 28 days of the mixes investigated are: B = 0.8% + C = kg/cm 2 per day B = 0.8% + C = kg/cm 2 per day B = 0% + C = kg/cm 2 per day B = 0% + C = kg/cm 2 per day The above mentioned results indicate that the strength gain of LWGM with beads is at faster rate than for the geomaterial without beads Curing Period (Days) B = 0.8% C = 8% B = 0.8% C = 10% B = 0% C = 8% B = 0% C = 10% Fig. 6 Strength gain with curing period, (i) & (ii) for LWGM, (iii) & (iv) for Fly ash-cement mix without EPS beads Effects of EPS Beads in Decreasing the Strength The compressive strength of the geomaterial in the form of mix of fly ash and cement decreases due to addition of EPS beads for making the material lightweight. The data on samples presented in Fig. 6 is analyzed and the same is given in Table 6. iv iii ii i

10 Dr. Y. S. Golait & A.S. Patode Table 6 Strength decrease caused by addition of beads Mix Composition B (%) Strength decrease (%) at 7 days 14 days 28 days FA + 8% C FA + 10% C Effect of Partial Replacement of Fly Ash by Soil Quite often suitable soil like loam type clayey silt may be available at the site of construction. In such a case partial replacement of fly ash by soil can be thought of in forming the composition of LWGM. In one typical case of LWGM of FA + 1.3%B + 6%C the strengths were determined for main component, M, consisting of fly ash only (sample20) and in another case with 30% replacement of fly ash by soil (sample 21). It was found that the strength of the LWGM got reduced by 19.23% due to this small replacement. Thus, it is evident that partial replacement of fly ash by soil is undesirable from strength point of view. SUGGESTED COMPOSITION OF EPS BEADS BASED LWGM Considering the main criterion in evolving the LWGM for its use in embankment construction and backfilling, as discussed earlier, the EPS beads based LWGM with composition of FA + 0.8% B + 8% C is considered more appropriate. This proportion is on weight basis. The composition on the basis of natural loose volume works out to be C:B:FA = 1:8:10. This material is expected to exhibit the properties: Unit Weight (soaked) = 1.07g/cc Unit Weight (dry) = 0.90 g/cc and UCS = 10.18kg/cm 2 In the problem of stability analysis of slopes and lateral earth pressure on walls, the shear strength parameters of the material are of more importance. These parameters (c and ϕ) for the suggested LWGM were determined by conducting the direct shear test. The wet mix of the required composition was used in forming the 3 identical samples of size 6cm x 6cm x 2.5cm (ht.) in cutters. These were inserted in the shear box after 7 days of curing. Normal stress of 0.5, 1.0 and 1.5 kg/cm 2 was used. The observed shear stress values at failure were 2.63, 2.81 and 3.02 kg/cm 2 respectively. The strength envelope was plotted for the test results. It gave strength parameters c and ϕ for the LWGM as c = 2.45 kg/cm 2 and ϕ = 21. In the traditional practice, coarse grained murum type soil is normally used in the construction of embankments and backfilling. Such a material actually used in Nagpur region was collected and its strength parameters were determined by conducting direct shear test for normal pressures of 0.5, 1.0 and 1.5 kg/cm 2. The respective observed values of shear stress at failure were 0.41, 0.63 and 0.89 kg/cm 2. The resulting strength envelope gave c-ϕ parameters for the traditional murum material as c = 0.18 kg/cm 2 and ϕ = 27. The Unconfined compressive strength test was also performed separately which gave UCS = kg/cm 2. The investigations revealed that the EPS beads based lightweight geomaterial of suggested composition has the following properties, as compared to those of traditional earth material: Unit weight is half the unit weight of soil. Cohesion is about 13.6 times that of soil. Unconfined compressive strength is about 16.5 times that of soil. CONCLUSIONS AND REMARKS (a) The lightweight geomaterial (LWGM) evolved from the study by using fly ash and expanded polystyrene beads has high potential for its use in several geotechnical constructions in infrastructure development works in India. (b) The composite material of required lightness and strength can be formed by adjusting EPS beads (B) content from 0.8% to 1.0% of weight of fly ash (FA). However, for appropriate strength development 6 to 10% cement (by weight) is needed. (c) The LWGM having composition C:B:FA = 1:8:10 (by volume) is considered appropriate for embankment construction on soft compressible grounds and for backfilling. This suggested material exhibits unit weights 1.07 and 0.90 g/cc under soaked and dry states

11 50 th respectively. Its strength properties are found as c = 2.45kg/cm 2, ϕ = 21 and UCS = kg/cm 2. (d) As compared to traditional coarse grained murum type earth commonly used in embankment construction and backfilling, the suggested LWGM is 50% light and 16.5 times strong. (e) The LWGM developed from the study can be used in the form of blocks of any size precasted and cured at casting yard near site or as wet mix to be placed in bulk for the desired construction job. (f) Embankments with very steep slopes can be formed by using LWGM. This results in substantial saving of land area occupied by embankment. Besides, the volume of embankment material is significantly reduced. REFERENCES 1. Horvath, J. S. (1991), Using geosynthetics to reduce earth load on rigid retaining structures, Proc. of Geosynthetics-91, Feb.1991, Atlanta, GA, USA, Stark, T. D. and Arellano, D. (2003), Design procedure for geofoam applications in embankment projects, Annual conference of ASCE, Kentucky Geotechnical Engineering Group, Lexington, KY. 3. Stark, T. D., Arellano, D., Horvath, J. S. and Leshchinsky, D. (2004a), Geofoam application in design and construction of highway embankments, Transportation Research Board, Washington, D. C., USA, NCHRP Web Document, Vol. 65, 792 pages. 4. Stark, T. D., Arellano, D., Horvath, J. S. and Leshchinsky, D. (2004b), Guideline and recommended standard for geofoam application in highway embankments, Transportation Research Board, Washington, DC., USA. NCHRP 529, 71 pages. 5. Lin, L. K., Chen, L. H. and Chen, R. H. L. (2010), Evaluation of geofoam as a geotechnical construction material, Jnl. of Materials in Civil Engg., ASCE, 22(2), Liu, H., Deng, A. and Chu, J. (2006), Effect of different mixing ratios of polystyrene pre-puff beads and cement on the mechanical behavior of lightweight fill. Geotextiles and Geomembranes, 24, Tsuchida, T., Porbaha, A. and Yamane, N. (2001), Development of geomaterial from dredged bay mud. Jnl. of materials in Civil Engg., ASCE, 13(2), Wang, F. and Miao, L. (2009), A proposed lightweight fill for embankment using cement treated Yangzi River sand and expanded polystyrene beads. Bulletin in Geological Environment 2009, 68, Qi, S., Liu, S., Zhang, Y. and Xu, G. (2013), Experimental study on capability of EPS beadsmixed lightweight soil. Applied Mechanics and Materials, vols , Deng, A. and Xiao, Y. (2010), Measuring and modeling proportion-dependant stress-strain behavior of EPS-sand mixture. Intl. Jnl. of Geomechanics, ASCE, 10(6), Padade, A. H. (2014), Experimental and numerical studies on expanded polystyrene geofoam-soil systems, Ph. D. Thesis, Indian Institute of Technology Bombay, Mumbai, May 2014, Padade, A. H. and Mandal, J. N. (2014), Expanded polystyrene based geomaterial with fly ash. Intl. Jnl. Geomechanics, ASCE, 14(6), 1-7.