Utilization of Silica-Based Admixture to Improve the Durability of Lime-Treated Expansive Soil

Abstract

Lime stabilization is widely used to improve the engineering properties of expansive soils. However, the durability of the lime-treated high-sulfate soil has been a persistent cause of concern for researchers and engineers. Treatment of a sulfate-rich soil with calcium-based stabilizers results in the formation of a highly deleterious compound known as ettringite. Ettringite crystals undergo substantial swell due to moisture ingress and cause considerable damage to pavements and light-weighted structures. In addition, the moisture intrusion during the early curing period has a detrimental impact on the strength and durability of the treated layers. An attempt was made in this research study to enhance the durability of lime-treated sulfate-rich soil using a crystalline silica-based admixture. The improvement in engineering properties over the traditional lime stabilization method was determined using a volumetric swell and strength test before and after subjecting the samples to moisture conditioning. Furthermore, the scanning electron microscope imaging was performed to identify the new reaction products in the treated soil and corroborate the observations of the engineering tests. The results indicate that the addition of crystalline-silica admixture has reduced ettringite-induced volumetric swelling from 45% to 3% and enhanced the retained UCS from 5 to 40 kPa.