Soil reinforcement using coconut fibre

Abstract

Soil reinforcement is a technique to improve the engineering characteristics of soil such as shear strength, compressibility, density and hydraulic conductivity. The primary purpose of reinforcing soil mass is to improve its stability, increase its bearing capacity, and reduce settlement and lateral deformation. In this Study, the effect of waste coconut fibre in reinforcing the soil was studied by carrying out direct shear test and unconfined compressive strength test. The results obtained were compared for two different soil samples taken from two different locations in KCAET campus. One soil sample from the area dominated by laterite (soil sample-1) and the second from sandy loam area (soil sample-2). According to direct shear test (DST) on soil sample-1 with fibre reinforcement of 0.15%, 0.25% and 0.35% , the increase in the cohesion value was found to be 12%, 7.1%, 6.6% respectively. Similarly the increase in internal angle of friction was found to be 4.4%, 5.3%, 0.85% respectively. The net increase in the value of cohesion and angle of internal friction were observed to be 28% (from 0.25 to 0.32kg/cm 2 ) and 10.9% (from 32to 35.5°) respectively. This increase was found to be substantial. But as per unconfined compressive strength (UCS) test for soil sample-1, with fibre reinforcement of 0.15%, 0.25% and 0.35%, the increment in the compressive strength were found to be 12.2%, 0.95% and 0.90% respectively. As this increment is not considerably significant, reinforcing soil sample-1 with coconut fibre is not recommended. According to DST on soil sample 2, with fibre reinforcement of 0.15%,0.25% and 0.35% the increment in the cohesion value were found to be 34.69%, 6.5%, 6.6% respectively. The increase in internal angle of friction was found to be 4.3%, 3.1%, 6.8% respectively. The net increase in the value of cohesion and angle of internal friction were observed to be 53.0% (from 0.3513 to 0.5375kg/cm 2 ) and 13.06% (from 27.82-32°) respectively. The result from UCS test for soil sample-2, with fibre reinforcement of 0.15%, 0.25% and 0.35%, the increment in the compressive strengthwere found to be 35.5%, 2.8%and 7.4% respectively. This increment is significant compared to soil sample-1.Hence reinforcing soil sample-2 with coconut fibre is much effective than soil sample-1.