A STUDY ON SOIL STABILIZATION USING LIME AND FLY ASH

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    29-Nov-2014

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This paper is based on a study conducted on the plastic clay type soil of KUMARAKAM.

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A study on soil stabilization using lime and fly ashPresented by, Sreelakshmi Sajeev Aswathy A.R Meera .J.Krishnan Aneena Elizabeth Jacob Liyamol Isen Resmitha Sasidharan Jose Nibin Uthup Kuwin Mathew

Introduction Roads

are an importation means of transportation Performance of pavements depend on quality of materials used in road construction. Subgrade is the base forming pavement Quality of subgrade significant If local soils not able to withstand loads,methods to enhance properties adopted

Stabilization and modification Stabilization

:blending and mixing materials with a soil to improve certain properties Modification: reducing plasticity and improving the texture of a soil

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Scope of the projectSubgrade soil of Kumarakom is plastic clay Low bearing capacity Requires greater maintenance Proves to be costly Difficulty to travel in monsoon seasons Hence stabilization to improve properties of the soil

Objectives of the projectTo explore the possibility of using fly ash in road construction programme. To study the effect of lime and fly ash on proctors density and OMC of clayey soil. To study the effect of lime and fly ash on the consistency limits of clayey soil. To study the changes in CBR of soil by the addition of lime and fly ash To study the effect of curing period on the properties of native soil

Uses of stabilizationQuality improvement. better soil gradation, reduction of plasticity index or swelling potential, and increase in durability and strength. In wet weather, used to provide a working platform for construction operations. Thickness reduction. As the strength and stiffness improves,design thickness can be removed.

Stabilization techniquesStabilization with Portland cement Portland cement used to increase the strength and durability. For stabilizing silt, sandy soils with small quantities of silt or clayey fractions Stabilization with bitumen basic mechanism involved is water proofing phenomenon. soil agglomerates coated with asphalt prevents penetration of water improve durability characteristics

contdStabilization with lime-cement and limebitumen one of the stabilizers in the combination compensates for the lack of effectiveness of the other more costly than single stabilizer methods, but economical in areas where base aggregate costs are high. Stabilization by geo-textiles and fabrics Geotextiles are permeable. Their permeability is compared to that of fine sand to course sand and they are strong and durable.

Stabilization with limedone by adding lime to soil Reaction involves exchange of cations in the adsorbed water layer decrease in the plasticity of the soil occurs lime-stabilized bases form a water resistant barrier which stops penetration of rain water. increase in optimum water content and a reduction in maximum density

..contdliquid limit of soil decreases but the plastic limit increases. plasticity index of the soil decreases strength of the lime stabilized soil improved: due to the decrease in the plastic properties of the soil and formation of cementing material Increase in the unconfined compressive strength is as high as 60 times. modulus of elasticity of the soil increases substantially

Mechanism of stabilizationPozzolanic reactions induces stabilization Reaction of silica and alumina in clay and calcium from lime Residual calcium keep the pH high enough to maintain the pozzolanic reaction soils with a PI that exceeds 10 and have more than 25 percent passing the #200 sieve

Mechanism: pozzolanic reactions

Stabilization with fly ashClass C fly ash -byproduct generated at coal fired power plants calcium compounds hydrate and produce cementitious products rate of hydration for flyash is more rapid than Portland cement. flyash has less effect on plasticity than lime.

Properties of flyashis non-plastic in nature. its moisture condition does not predominantly affect the dry density. has high angle of internal friction. silt size material

List of experimentsAtterberg limits Specific gravity Direct shear test Proctor compaction test CBR test Unconfined compression test(UCS)

MATERIALS USED

Clayey soil :From kumarakom Additives : fly ash lime

Properties of native soilSl No: 1 2 3 4 5 6 Properties CBR value Max.dry density Values 4.3% 1517 kg/m3

Optimum 20% moisture content Liquid limit Plastic limit Plasticity index 36% 26% 10

The lime percentage was fixed at 10% and flyash 14% based on UCS test

Properties of fly ashPhysical properties Specific gravity Loss on ignition Chemical composition Silica (SiO2) 58.3% Alumina (Al2O3)+Iron oxide 26.3% (Fe2O3) Calcium oxide (CaO) 2.2% 2.27 11.8%

Lab testing programme

Compaction test to determinethe quantity of water to be added for field compaction of soil and resultant density expected. Compaction of clay,clay-lime and clay-flyash mixtures were carried out using standard proctor test with three layers on each 25 blows. Samples for conducting compaction tests were prepared using moulds of dimensions 10 cm diameter and 15 cm height. In this study, lime is added for about 10% and cured for 3, 7, and 14 days. Also,flyash is added for about 14% and is cured for 3,7 and 14 days. The values of optimum moisture content and maximum dry density are obtained in a plot of dry density versus moisture content.

CBR

UCC