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Nagrale Prashant P, Katkar Surendrakumar R, Patil Atulya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 5, September- October 2012, pp.1445-1452 Finite Element Modeling Of Lime Stabilized Low Volume Rural Roads Nagrale Prashant P*, Katkar Surendrakumar R**, Patil Atulya*** *(Associate Professor, Sardar Patel College of Engineering, Andheri (w), Mumbai-58) ** (Executive Engineer, Public Work Department, Pune) *** (Research Scholar, Sardar Patel College of Engineering, Andheri (w), Mumbai58)ABSTRACT The present study was undertaken to and sophisticated characterization of materials thatevaluate the strength characteristics of lime can be easily accommodated in the analysis. Thestabilized subgrade soils. Two types of soils (Soil escalating cost of materials and energy and lack of– A and Soil – B) and one type of lime was resources available have motivated highwayselected for present study. Maximum Dry engineers to explore new alternatives in buildingDensity, L.L., P.L. and CBR test w1ere rural roads and rehabilitating the existing ones.conducted on these soils stabilized with 2.5 %, 5 Stabilizing the subgrade with lime or cement is one%, 7.5 % and 10 % lime content. It was observed such alternative. Recently considerable interest hasthat 7.5 % lime content will be the optimum for been generated among both highway engineers andgetting maximum benefits. The four days soaked contractors for these materials as a stabilizer in theCBR value of subgrade Soil – A and Soil – B was low volume rural roads. However, absence of a well1.0 % and 1.76 % respectively, it was increased documented design procedure for stabilizedto 6.51 % and 5.91 % respectively due to pavement has resulted in low confidence in highwaystabilization with 7.5 % lime content. engineers in using these materials. The static triaxial test were conductedon unstabilized and stabilized subgrade with 7.5 2. LITRATURE REVIEW% lime content as well as on other pavement The world wide literature review has beenlayers at a confining pressure of 40 kPa and conducted on soils stabilized with lime, cement, flystress- strain curve were plotted. These stress- ash, mixture of these material and fibre reinforcedstrain data further used as a input parameter in soil mixed with lime, cement or fly ash presentedelasto-plastic finite element modeling. The here.vertical compressive strain developed at top of Consoli et al[1] carried out drained triaxialunstabilized and stabilized subgrade further used compression test to study the individual andfor estimation of extension in service life or combine effect of cement and randomly distributedreduction in layers thickness of the low volume fibre inclusions on the properties of silty sand. Limarural roads. et al.[2] observed large increase in compressive strength due to addition of lime and cement to fibreKeywords-CBR, Finite element modeling,lime reinforced soils. Schaefer et al.[3] reported amountstabilization,LTR,Rural road,TBR of cement required for stabilizing expensive soils in the range of 2 % - 6 % by weight of soil. Cocka [4]1. GENERAL reported that the lime, cement and fly ash reduced Rural roads are the tertiary road system in the swelling potential of expansive soil. The limetotal road network which provides accessibility for and cement were introduced as an admixture up to 8the rural habitations to market and other facility % by weight of soil. Consoli.et al.[5] conductedcenters. In India, during the last six decades, rural unconfined compression strength test and triaxialroads are being planned and programmed in the strength test to evaluate the behavior of sandy soilcontext of overall rural development. While building stabilized with lime and fly ash. They conducted therural roads, the provisions based on the parameters test on sandy soil with 25 % fly ash and 1 % - 7 %that affect the sustainability are to be made at carbide lime. The results have shown that maximumminimum cost. Rural roads in India are constructed dry density of sandy soil decreases due toover difficult and poor sub grade. Such subgrades stabilization with lime and fly ash but there ishaving low strength this leads to more thickness of marginal effect on optimum moisture content. Theythe pavement. It is the duty of the engineers to spend also reported that the rate of gain of strength is theevery rupee of the tax payer’s money with optional function of percentage of lime and curing time.utility particularly under resource constraints. This Schnaid et al. [6] studied the stress-strain behaviorcalls for introduction of innovative approaches in of cement stabilized sand through unconfinedrural road building for achieving cost-effectiveness. compression strength test and triaxial compressionA finite element model of pavement layered test. They reported that the initial tangent modulusstructures provides the most moderate technology of uncemented sand at confining pressure of100 1445 | P a g e
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Nagrale Prashant P, Katkar Surendrakumar R, Patil Atulya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 5, September- October 2012, pp.1445-1452kN/m2 was 54 MN/m2 this value was increased to600 MN/m2, 3090 MN/m2 and 10000 MN/m2 due toaddition of 1%, 3% and 5% cement respectively. The soil stabilization with lime, cement andfly ash has been tried for many years and there isconsiderable improvement in strength properties.Available literature shows that most of the researchworks on cement and lime stabilization is related togeotechnical aspect only. Very few attempts havebeen made on use of cement or lime in highwaysubgrade. Conflicting results have been reported inliterature regarding optimum percentage of lime orcement required for soil stabilization. The presentstudy was undertaken to observe the effect of limestabilization on properties of soil important indesign and analysis of low volume rural roads.3. NEED FOR DEVELOPMENT OFDESIGN CHARTS The present study is concentrated on thedevelopment of design charts for rural roads toconvert the locally available troublesome soil tosuitable construction material. The design charts areparticularly customized for low volume rural roads.The Indian Practice Code IRC 37-2001 [7]fordifferent traffic intensity and IRC: SP: 72-2007[8](Guidelines For the design of flexible pavementsfor low volume rural roads) are used as the standard Outline of M-E pavement design guide processfor designing. These practice code uses 4 dayssoaked CBR value of subgrade soil for design. But 4. EXPERIMENTAL PROGRAMthe major draw back of CBR method is, it is 4.1 Material Selection Twopenetration test and maximum penetration of types of soils and one type of stabilizer namely limeplunger is as high as 12.5 mm which may not be is selected in present study. The soil used availablerealize in actual practice. Keeping in view the above in the campus of Sardar Patel College ofdraw backs of existing methods it is urgent need to Engineering, Andheri (W) Mumbai. In the presentdevelop the mechanistic – empirical pavement (M-E study this soil is referred to as subgrade Soil – A andpavement) design approach for design of Low Soil - B. The index properties; liquid limit, plasticvolume rural roads. This methodology has better limit and plasticity index were determined as percapability to characterization of different material ASTM-D 4318.[9] The Proctor’s tests wereproperties and loading conditions and has ability to conducted as per ASTM-D 1557[10] for decidingevaluate different design alternatives on economical the maximum dry density (MDD) and the optimumbasis. moisture content (OMC) for of soil. Fig.1 shows the particle size distribution curve for subgrade soil – A3.1 How Does Mechanistic Pavement Work? and B. The important soil properties as per HRB and The following description is necessarily US soil classification systems are presented in Tablesomewhat generic and based primarily on the 1. The Soil - A is clay of low Plasticity (A-6) andanalysis of flexible pavement; however the system soil – B is of sandy silt of low plasticity (A-2-6).has been designed in a modular fashion, which withthe modular nature of the software, allows the sameelements of design with type-specific sub-modules.The M-E pavement design guide performs a time-stepping process, illustrated in the diagram below. 1446 | P a g e
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Nagrale Prashant P, Katkar Surendrakumar R, Patil Atulya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 5, September- October 2012, pp.1445-1452TABLE 1 physical properties of subgrade Soil-A TALE 2 Effect of Stabilization on Dry Density ofand soil-B subgrade soils 4. 2.2 Effect on California Bearing Ratio (CBR) Test CBR tests were conducted on unstabilised and stabilized soils with different lime contents as per ASTM D1883[11] The maximum limit of lime content was 12.5 percent. A total of 14 samples were tested for the subgrade soil - A and B at different lime content. Weight of soil sample at each percentage of lime content required for test is determined by volume of mould and corresponding maximum dry density obtained from proctor test. Soil sample and lime is mixed properly in dry state and water corresponding to Optimum Moisture Content (OMC) is added. The soil sample after mixing is filled in the mould and compacted by static compaction. It is soaked in water for four days and the sample is tested in CBR testing machine. The CBR was determined at 2.5 mm and 5.0 mm penetration levels and maximum of this is adopted as CBR value. CBR values at different lime content4.2 Determination of Optimum Quantity of Lime and percentage increase in CBR with respect to4.2.1 Effect on Proctor’s Test unstabilized soils are presented in Table 3. As can The standard proctor tests were carried out be seen, the CBR value of unstabilized soil – A andon the unstabilized and stabilized soils subgrade B is 1 % and 1.76 % this increase to 6.51 % andSoil – A and B as per ASTM D1557 [10].Soil mixed 5.91 % due to addition of 7.5 % lime respectively,with different percentages of lime varies from 2.5 % thereafter it start decreasing. It shows thatto 12.5 % at the step of 2.5 % by dry weight of soil. maximum improvement in CBR is observed whenThe dry density – moisture content relations were subgrade soil – A and B stabilized with 7.5 percentplotted for each test. Then optimum moisture lime content. Also, it indicates that lime stabilizationcontent and maximum dry density at each is more effective for weak soil compared to strongerpercentage of lime content were evaluated. Fig. 2 one.gives typical plot showing variation of dry density TABLE 3 Effect of Stabilization on CBR value ofwith moisture content for unstbilised subgradet soil subgrade soil–A and soil stabilized with 2.5 % lime content.Similar plot are made for other test condition andvariation of maximum dry density and optimummoisture content for stabilized soil at different limecontent have been summarized in Table 2. Themaximum dry density for these soils decreasesgradually with increase in the lime content, which isdue to the light weight of the lime replacing the soilparticles and some of the applied energy ofcompaction absorbed by the lime.The change inOMC was quite marginal. 1447 | P a g e
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Nagrale Prashant P, Katkar Surendrakumar R, Patil Atulya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 5, September- October 2012, pp.1445-14524.2.3 Effect on Elastic Modulus ( E i - value) andFailure Stress ( f ) The triaxialtests were conducted on unstabilized and soilstabilized with optimum lime content. The sixteenspecimens were prepared for unstabilized andstabilized subgrade soil and tested at confiningpressures of 40, 70,120 and 150 kPa. The specimensof ize 10 cm diameter and 20 cm height wereprepared in split mould. The soils were dried at 1000C for 24 hours, pulverized manually and sieve itthrough 4.75 mm sieve. The weight of lime and soilwere calculated using the Proctor density andvolume of split mould. The lime were mixed in soilin dry state and water corresponding to OMC wasadded and mixed thoroughly again. The moistmixture was transferred to split mould in three equal 5. ELASTO-PLASTIC ANALYSISlayers; each layer compacted by a light weight The finite element method was used tohammer of weight 1.5 kg. Around 25 numbers of analyze the rural road pavement section resting onblows were imparted for compacting each layer so unsterilized and stabilized subgrade soils. Thethat uniform density achieved throughout the depth. software ANSYS was used. The ANSYS elementThe curing time of 3 days were maintained for all library contains more than 150 different elementsspecimens before test. The modulus of elasticity is and is capable of handling linear, nonlinear, staticusually calculated from straight portion of stress- and dynamic 2-D and 3-D problems. In the presentstrain curve. For most of the cases, however, the study, the section was modeled as a 2-D axisymetricstress strain curve of the soil is nonlinear since onset problem with 8-noded structural solid element. Aof loading. So, the modulus of elasticity was four - layer low volume rural road section wascalculated corresponding to the initial tangent of the considered and analyzed. The thickness of eachstress-strain curve. layer in the pavement section resting on unsterilized The values of Elastic modulus ( E i - value) subgrade soil was designed as per Indian code of practice (IRC: SP:72-2007) [8] The thicknesses ofof unstabilized and stabilized subgrade soil - A and each layer above the subgrade, initial tangentB at a confining pressure of 70 kPa were 78 kg/cm2 modulus of subgrade soil and other pavement layersand 121 kg/cm2 respectively. These values were required for analysis are reported in Table 5 (a) andincreased to 102 kg/cm2 and 147 kg/cm2 (b). A pressure equal to single axle wheel load isrespectively due to stabilization with 7.5 % lime assumed to be applied at the surface and distributedcontent. The values of Elastic modulus ( E i - value) over a circular area of radius 150 mm. Forof unstabilized and stabilized subgrade soil - A and application of FEM in the pavement analysis, theB at different confining pressure are presented in layered system of infinite extent is reduced to anTable 4. The stress-strain curves were drawn for approximate size with finite dimensions. Chiyyarathunstabilized and stabilized soil samples to study the and Lymon adopted fixed right hand boundary at aeffect of lime on failure stress. The unstabilized distance 4a from axis of the symmetry where a is thespecimens of soil - A, and B at a confining pressure radius of the loaded area. In the present study rightof 40 kPa attained a failure stress of 2.1 kg/cm2 and hand boundary is provided at 110 cm from the outer3.05 kg/cm2 respectively, at an axial strain of 7.0 edge of loaded area, which is more than 4 timespercent, and 6.5 percent respectively. The lime loaded radius. This approximation will; however hasstabilized specimens exhibited highly ductile little influence on the stress and strain distribution inbehavior. The value of failure stress of stabilized finite element model ,(Desai and Abel, 1972)[12]soils - A and B increased to 3.62 kg/cm2 and 6.03kg/cm2 at an axial strain of 9 % and 8 % TABLE5 (a) Initial Tangent Modulus. ofrespectively. The variations in failure stress and Subgrade for FE Analysisfailure strain with confining pressure are reported inTable 4.TABLE 4 Effect of confining pressure on ElasticModulus ( E i - value), Failure Stress ( f ) andFailure Strain of Unstabilized and StabilizedSubgrade Soil – A and B. 1448 | P a g e
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Nagrale Prashant P, Katkar Surendrakumar R, Patil Atulya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 5, September- October 2012, pp.1445-1452Table 5 (b) Initial Tangent Modulus of PavementMaterial for FE and D D Et1 , t1 j (4b) j Analysis. iv) Equilibrated force vector will then be given by, F B DB dv eq 1 j T 1 j (5a) v Therefore, the residual force vector, 1j F 1 Feq 1 j j (5b)DBM – Dense Bituminous Macadam, BC – Bituminous Concrete. v) Check for convergence, The elasto-plastic analysis was carried outto evaluate the primary response of the pavement j T j 0.5 100 ToleranceLimit F F 1 1resting on unsterilized and stabilized subgrade soils. 0.5 (6) j T jThe multilinear isotropic hardening model (MISO) 1 1available in ANSYS was used to evaluate thestresses, strains and deformations with in the th th In general, for any i iteration of the jpavement sections. The mixed incremental methodis used in present study for elasto-plastic analysis of load increment, force-displacement equation system will be - ij1 K j 1 ij2-D axisymetric finite element model. This methodcombines the advantages of both the incremental (7a)and the iterative schemes. The external load, here, isapplied incrementally, but after each increment,successive iterations are performed to achieve where K j 1 is the constant stiffness matrixequilibrium. obtained from the state of stress and strain attained at the end of the j 1 load increment. th th In general, for the j load increment, thestate of deformation, stress and strain at the end of Therefore, j 1th load increment is known, i.e. ij K j 1 1 ij (7b) j 1 , j 1 , j 1 are known, the subscripts ij B ij (7c) j 1 refers to the load increment. The general ij D ij (7d)procedure of this method is follows, thi) For the first iteration of the j load increment, The accumulated state of deformation, strain andF j K j 1 j (1) stress is given by, ij j 1 ij 1 1 (8a)which can be solved to obtain, ij j 1 ij (8b) 1j K j 1 1 F1j (2a) ij j 1 ij (8c)obtain, B 1 j 1 j (2b) 1j D 1j The state of principal stresses and strains will be and (2c) j jii) Accumulated displacements, strains and stresses given by p i and p i respectively, and theat the end of 1th iteration can be expressed as, tangent modulii by E j ti , ti j and the elasticity j 1 j 1 j (3a) matrix, D DEtij , tij 1 (9) j j 1 j (3b) The equilibrated force vector, F B DB dv 1 1 j T eq i (10) 1 j j 1 1 j (3c) v and the residual force vector, ij ij1 Feq ij jiii) Obtain the principal stresses, p 1 and strains, (11) p 1 j and then, The check for convergence will be given by,E t1 and t1 = f p 1 , p j j j j 1 (4a) 1449 | P a g e
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Nagrale Prashant P, Katkar Surendrakumar R, Patil Atulya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 5, September- October 2012, pp.1445-1452 j T j 0.5 100 ToleranceLimit (12) stabilization benefits in terms of extension in service i i life and reduction in layer thicknesses. 0.5 Haas et.al[13], Webstar, [14], quantified j T i 1 j i 1 the benefits of geogrid reinforcement in a pavement the equilibrium and therefore the in terms of traffic benefits ratio (TBR). It gives theconvergence for jth load increment is considered to extension in service life of the pavement. The TBRhave been achieved when this force residual is can be written in the equation form asbellow certain tolerance level, otherwise iteration NRare continue until the above iteration satisfied. Once TBR (13)the convergence is achieved, the next NU j 1increment F1 is applied and the process is N number of traffic passes required for producing arepeated until the final load level is reached. In this pavement surface deformation (rutting) upto themethod, the equilibrium can be achieved at the end allowable rut depth, mmof every load increment. It makes use of a variable R and U denote reinforced and unreinforcedstiffness matrix for each new load increment while pavement section.maintaining it constant within a given load The structural failure in flexible pavementsincrement so as to achieve convergence and are of two types, fatigue failure, due to horizontaltherefore the equilibrium iteratively. tensile strain at the bottom of bituminous layer and rutting failure, which is due to vertical compressive strain at top of subgrade. The rutting is considered6. EVALUATION OF STABILIZATION as a failure criterion in the present study. IRC 37-BENEFITS 2001 consider a rut depth of 20 mm with rutting The Mechanistic – Empirical pavement equation given asdesign approach has been used in present study to 4.5337evaluate the benefits of stabilizing subgrade soil in 1 terms of reduction in layer thickness and extension N 20 4.1656 *10 8 (14)in service life of the pavement. The present V methodology has better capability to Where, N20 = Number of cumulative standard axlecharacterization of different material properties and required to produce a rutting of 20 mm.loading conditions and has ability to evaluate v = Vertical compressive strain at top ofdifferent design alternatives on economic basis. The subgradevarious design alternatives consider in present study As there is no separate equation availableare. in the literature to relate the vertical compressive(1) Same service life of stabilized and unstabilized strain at top of stabilized subgrade to the number of section, it would leads to reduction in layer load repetition necessary to produce a allowable thicknesses and has been expressed in terms of rutting. The equation 14 was used for both layer thickness reduction (LTR). unstabilized and stabilized sub grade. Using(2) Same pavement section for stabilized and equations 13 and 14 the benefits of stabilizing unstabilized pavement section, it would result subgrade in terms of extension in service life of the in more service life of pavement due to pavements can be expressed as: stabilization and has been expressed in terms of B traffic benefits ratio (TBR). N TBR S VS N US VUS The vertical compressive strain developed (15)at top of unstabilized and stabilized subgrade soil - A and B was captured for different thicknesses of Where: N is the number of traffic passessubbase and base for subgrade soil - A and B. the required to produce an allowable rut depth in thethickness of base 150 mm was maintained constant pavement.and subbase thickness was varied. Again, the v is vertical compressive strain at the top ofsubbase thickness 200 mm was maintained constant subgrade that can be obtained through FEM.and base was varied. The vertical compressive strain Symbols S and US denote stabilized anddeveloped at top of subgrade was captured for each unstabilized pavement section. B is constant =of these alternatives. Fig. 3 and 4 shows the 4.5337.variation of vertical compressive strain with subbase The result of elasto-plastic finite elementthickness for constant base for pavement section analysis shows that for constant thickness of baseresting on unsterilized and stabilized subgrade soil - equal to 150 mm, the vertical compressive strainA and B. whereas, Fig. 5 and 6 shows the variation developed at top of subgrade soil - A in pavementof vertical compressive strain with base thickness section designed for unstabilized subgrade is 4876.1for constant subbase for pavement section resting on micron, the same strain level is obtain for subbaseunsterilized and stabilized subgrade soil - A and B. thickness of 165 mm in case of stabilized subgradethese plots further used for evaluating the soil – A (Fig. 3). similarly, for a constant thickness 1450 | P a g e
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Nagrale Prashant P, Katkar Surendrakumar R, Patil Atulya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 5, September- October 2012, pp.1445-1452of subbase equal to 200 mm, the verticalcompressive strain developed at top of subgrade soil 7.CONCLUSIONS- A in pavement section designed for unstabilized 1. The four days soaked CBR value of subgrade soilsubgrade is 4876.1 micron, the same strain level increases considerably due to lime stabilization andobtained for a base thickness of 120 mm (Fig.5). It it is the function of soil type and lime content. Also,indicates that if the same service life for both it observed that the CBR value of subgrade soilunstabilized and stabilized subgrade pavement is increase rapidly up to 7.5 % lime content thereafterconsidered than the thickness of subbase is reduced it start decreasing, hence optimum quantity of limeby 35 mm and that of base reduced by 30 mm. assumed to be 7.5 %. 2. The initial tangent modulussimilar types of results observed when pavement of subgrade soil - A and B at a confining pressure ofresting on stabilized subgrade – B. 40 kPa is found to be 56 kg/cm2 and 72 kg/cm2If the pavement section is kept same for both respectively it increase to 76 kg/cm2 and 91 kg/cm2unstabilized and stabilized subgrade the vertical respectively due to stabilization with optimumcompressive strain developed at the top of percentage of lime.unstabilized subgrade – A is found to be equal to 3. If the pavement section is kept same for both4876.1 micron this value reduce to 3550 micron due unstabilized and stabilized subgrade the verticalto stabilization, it gives TBR of 4.22. It means that compressive strain developed at the top ofthe stabilized pavement will have life which would unstabilized subgrade – A is found to be equal tobe 4.22 times that of unstabilized pavements. 4876.1 micron this value reduce to 3550 micron dueSimilar types of exercise can be done for other to stabilization.conditions also. 4. For constant thickness of base, the thickness ofAll these results have been summarized in subbase is reduced by 17.5 % and 12.5 % for pavement section resting on stabilized subgrade ATable 6 and B respectively.TABLE 6 Stabilization Benefits in Subbase and 5. For constant thickness of subbase, the thicknessBase of Low Volume Rural Road of base is reduced by 20 % and 16.67 % for pavement section resting on stabilized subgrade A and B respectively. [5] Consoli, N.C., Prietto, P.D.M.,REFERENCES Carrath, J. A. H., and Heineck, K.S. [1] Consoil, N.C., Prietto, P.D. and Ulbrich, (2001), “ Behaviour of Compacted L. A. (1998), “Influence of Fibre and Soil – Fly Ash – Carbide Lime Cement Addition on Behaviour of Sandy Mixture”, J. Geotechnical and Soil”, J. Geotechnical and Geoenviornmental Engineering, Vol- Geoenviornmental Engineering, Vol. - 127 (9), ASCE, pp. 774 to 782. 124 (2), ASCE, pp. 1211 to 1214. [6] Schnaid, F. Prietto, P.D.M. and [2] Lima, D.C. Bueno, B.S. and Thomasi, Consoli, N.C. (2001), L. (1996), “Mechanical Response of “Characterisation of Cemented Sand Soil - Lime Mixture Reinforced with in Triaxial Compression”, J. Short Synthetic Fibres”, Proceeding: Geotechnical and Geoenviornmental IIIrd International Sympson on Envr. Engineering, Vol. - 127 (10), ASCE, Geotechnology, Vol. - I, pp. 868 to pp. 857 to 867. 877. [7] IRC37-2001, “Guideline for the [3] Schaefer, V. R., Abramson, L.M., Design of Flexible Pavements”, Indian Drumheller, J. C. and Sharp, K.D. Roads Congress, New Delhi. (1997), “Ground Improvement, [8] IRC:SP:72-2007, “ Guidelines for the Ground Reinforcement and Ground Design of Flexible Pavements for Low Treatment: Developments 1987- Volume Rural Roads” 1997”, Geotech Special Publication [9] ASTM D 4318 (2000), “Standard No.69, ASCE, New Yark. Method for Liquid limit, Plastic Limit, [4] Cokca, E., (2001), “Use of Class-C and Plasticity Index of Soils”, Fly Ash for the Stabilization of an American Society for Testing and Expansive Soil”, J. Geotechnical and Materials, West Conshohocken, Geoenviornmental Engineering, Vol. - Pennsylvania, USA. 127 (7), ASCE, pp. 568 to 573. [10] ASTM D 1557 (2002), “Standard Test Method for Laboratory Compaction 1451 | P a g e
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Nagrale Prashant P, Katkar Surendrakumar R, Patil Atulya / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 5, September- October 2012, pp.1445-1452 Characteristics of Soil Using Modified the Granular Bases in Flexible Effort”, American Society for Testing Pavements.” TRR 1188, and Materials, West Conshohocken, Transportation Research Record, Pennsylvania, USA. Washington, D. C., USA, pp 19-27.[11] ASTM D 1883 (1999), “Standard [14] Webstar, S. L. (1992), “Geogrid Method for CBR (California Bearing Reinforced Base Courses for Flexible Ratio) of Laboratory Compacted Pavements for Light Aircraft: Test Soils”, American Society for Testing Section Construction, Behaviour under and Materials, West Conshohocken, Traffic, Laboratory Test and Design Pennsylvania, USA. Criteri”. Technical Report GL-93-[12] Desai, C. S. and J. F. Able.” 6,ASCE Waterway Experiment Introduction to finite element Method. Section, Vicksburg, Mississippi, USA, Ven Nostrand Reinhold Co. New york, pp 886-896. USA, 1972.[13] Hass, R., Jamie Walls and Carrol, R. G. (1988), “Geogrid Reinforcement of 1452 | P a g e
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