Unconfined compressive strength and California Bearing Ratio test on clay stabilization using silica sand

Abstract

Clay is a soil with certain particles which has plastic properties when it is mixed with water, so that clay needs to be stabilized before it is ready to be used. In this study, the stabilizing agent used was silica sand, which is a mineral commonly found and has a hexagonal crystal structure (SiO2). The purpose of this study was to determine the effect of adding silica sand to the properties index, Unconfined Compressive Strength (UCT), and California Bearing Ratio (CBR) value of clay soil. The result showed that according to AASHTO this soil was classified as A-7-6 (9) and according to USCS it was classified as CL (Clay - Low Plasticity). The original soil sample has a moisture content of 34.43%; specific weight of 2.65%; liquid limit of 47.33%; plastic limit of 17.45%; and plasticity index of 29.88%. The values of unsoaked design CBR and UCT for the original soil were 6.29% and 1.42 kg/cm2. Among all the variations, the mixture of 30% silica sand reached the optimum value of soaked California Bearing Ratio which is 14.86%, meanwhile, the mixture of 12% silica sand reached the optimum value of free compressive strength in Unconfined Compression Test which was 2.90 kg/cm2.