Influence of Precompaction Delay Time on Geoengineering Properties of Expansive Soil Treated with Geopolymer and Conventional Stabilizers

Abstract

This paper reports the influence of delay time on the index and engineering properties of geopolymer-, cement-, and lime-treated expansive soil. Locally available expansive soil was treated with different doses of slag-based geopolymer, cement, and lime. The index and engineering properties like Atterberg’s limits, free swell index, grain-size distribution, compaction properties, and unconfined compressive strength (UCS) were evaluated at delay periods of 0, 6, 12, 24, 48, 72, and 168 h. Further, the mineralogical characteristics and microstructure of the stabilized materials were examined using X-ray diffraction (XRD) and scanning electron microscopic (SEM) images. It was observed that with an increase in delay time, the plasticity and swelling characteristics of the treated soil reduced with improvement in the soil grain size along with the formation of hydration and geopolymeric compounds. The delay in compaction results in the decline of the compacted density and UCS. The formation of hydrated products and flocs during the delay period caused loose packing under dynamic loading and affects the mechanical properties. A significant improvement in plasticity and engineering properties of the expansive soil was observed with geopolymer stabilizers. Thus, it is noteworthy to consider geopolymers as a new generation eco-friendly stabilizer for treating expansive clays for geotechnical constructions.