Investigative Studies on Thermo-Mechanical Properties of GGBS-Stabilized Expansive Soil

Expansive soils often pose significant challenges to engineers, especially under thermal regimes. Hence, an attempt to improve their properties comes with concerns about their response to temperature (climate) changes. Therefore, this study examines the thermal and mechanical behavior of expansive soil stabilized with ground granulated blast furnace slag (GGBS), a calcium-rich industrial by-product. Laboratory experiments were performed on soil amended with 0 to 30% of GGBS to evaluate the liquid limit, plasticity index, differential free swell index, compaction parameters, unconfined compressive strength test, and thermal conductivity. The results revealed significant improvements with increasing GGBS content. At 30% replacement, the liquid limit and plasticity index decreased by 21.9% and 48%, respectively, while the DFSI dropped from 81.03% to 46.83%. Compaction characteristics improved, with maximum dry density rising from 1.37 g/cc to 1.516 g/cc, and optimum moisture content reducing from 30.29% to 25.25%. The strength parameters also showed marked enhancement, as UCS increased by 103.6%, reaching a peak of 162.23 kPa. In addition, thermal conductivity improved steadily from 0.962 W/mK in untreated soil to 1.822 W/mK at 30% replacement, reflecting an overall gain of 83.39%. These results highlight the potential of GGBS as a sustainable stabilizer for enhancing both mechanical and thermal performance of expansive soils in critical geotechnical applications such as pavements, landfills, and energy structures, where heat transfer and load-bearing performance are interdependent.