STABILIZATION OF LOW PLASTIC AND HIGH PLASTIC SOIL USING GYPSUM AND RICE HUSK ASH

Abstract

Construction on clays is mostly found problematic due to their despoiled properties, i.e., low bearing capacity, low Unconfined Compressive Strength (UCS), high swell potential, high compressibility, and low permeability. Problems associated with clays are mainly foundation failures, floors upheave, diagonal cracks in the walls and cracks in canal linings. The best suitable and economical way to tackle the problem is soil stabilization. This study is conducted to check the potential of Gypsum and Rice Husk Ash (RHA) as soil stabilizers for low plastic clay (CL) and high plastic clay (CH). Gypsum is locally available in abundance while RHA is agricultural waste produced by burning of rice husk which is also available in abundance all over Pakistan. Atterberg limits, compaction properties, Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR) and swell potential of untreated and treated soils were analyzed. Liquid Limit (LL) and Plasticity Index (PI) of both CL and CH decreased by the use of Gypsum and RHA. Optimum Moisture Content (OMC) of the treated soil increases while Maximum Dry Density (MDD) decreases due to flocculation of soil particles. UCS of CL treated with Gypsum and RHA increases 18 and 5.5 times while that of CH increases 20 and 4.45 times under soaked and unsoaked conditions respectively. The value of CBR for CL for untreated soil lies within the range of poor subgrade material while after treatment, soil was considered as good subgrade material. One dimensional swell potential of CL was reduced 6 times when treated with Gypsum and RHA while the reduction in the swell potential of CH was 40 times. The results of this study concluded that Gypsum and RHA are effective soil stabilizers.