Experimental Studies and its Application using PLAXIS-2D for Lithomargic Clay Stabilized by GBFS and Lime

Abstract

Lithomargic clay is found along the Eastern and Western coasts of Southern India. Presence of weak soils like lithomargic clay below the foundations, cause serious problems when they come in contact with water, and non-availability of stronger fill materials locally, to replace them is a challenge to foundation engineers. An attempt has been made in this paper to improve the strength of lithomargic clay by chemical stabilization using Lime and Granulated Blast Furnace Slag (GBFS). Disposal of massive amounts of industrial waste, GBFS, has become an environmental problem and utilization of the same for soil stabilization would be a sustainable solution for disposal. To optimize the use of lime and understand the mechanism behind the gain in strength, laboratory experiments were conducted on lithomargic clay, by replacing it with varying amounts of GBFS and addition of different percentages of lime. The optimum lime and GBFS content were found to be 4% and 20% respectively. Further optimization was done by mixing lithomargic clay with 4% lime and 20% GBFS and a significant strength improvement was observed. SEM and XRD analyses were conducted on the stabilized soil and the increase in strength was established from structural changes and formation of compounds like CSH and CASH. PLAXIS 2D was used to understand the settlement behavior of both the unstabilized and stabilized soils below strip foundations of varying widths. From load settlement analysis, it was observed that the net allowable pressure increases with increase in GBFS content and further increases with addition of lime to soil stabilised with optimum GBFS.