Use of Gypsum Waste and Tin Tailings as Stabilization Materials for Clay to Improve Quality of Subgrade

Abstract

Clay is a soil with low stability, so an effort is needed to improve soil stability in order to improve the quality of subgrade. In this study, an effort was made to improve soil stability by adding gypsum waste and tin tailings as a mixture in clay. Gypsum waste and tin tailings have not been utilized optimally in Bangka Belitung Province, so the research needs to be done to determine the effect of using gypsum waste and tin tailings as a material for stability of clay. The tests of soil characteristics carried out in this study were sieve analysis, soil specific gravity, compaction and direct shear test. In this study, the addition of gypsum waste and tin tailings in soft soil with 4 variations, namely clay with additional 8% gypsum waste and 20% tin tailings, clay with additional 8% gypsum waste and 30% tin tailings, and clay with addition 8% gypsum waste and 40% tin tailing, besides that, testing of the original soil was also carried out. The results of sieve analysis test showed that the addition of gypsum waste and tin tailings to clay soils could change the gradation of clay. Addition of gypsum waste and tin tailings on clay soil increases cohesion (c) dan shear angel value so that increases soil shear strength. From the results of the study, the addition of gypsum waste and tin tailings can improve the stability of clay so Improve Quality of Subgrade.