The effect of gypsum plafond waste on shear strength of soft clay soil

Abstract

One type is soft clay soil which has a low compressibility and high water content that causes the carrying capacity of the soil to be low. In this research, soil improvement was carried out chemically by soil stabilization method using a mixture of gypsum plafond waste with a percentage of 5 %, 10 %, 15 %, 20 %, and 25 % in a laboratory scale. Soft clay samples used for the study were taken in the Pakjo area of Palembang, South Sumatra. The use of gypsum plafond waste as a mixture was expected to increase the shear strength of soft clay. Tests carried out include testing Direct Shear. Based on the USCS classification, the soil was classified as CH and based on AASHTO classification was A-7-6. The value of wop is 22 % (optimum moisture content) and the value of γdmax is 1.74 gr/cm3 (maximum dry weight). The maximum cohesion (c) value is 24.20 kPa from 15 % mix of gypsum plafond waste (WPG15) sample. For the maximum value internal friction angle (ϕ) is 16.36 °C from 5 % mix of gypsum plafond waste (WPG5) sample. The maximum shear strength (τ) is 26.57 kPa from 5 % mix of WPG15 sample.