Stabilizing Expansive Soil in Subgrade using Cementitious Materials

This study investigates the effectiveness of stabilizing expansive soil within subgrade layers using cementitious materials. Expansive soils, characterized by their significant volume changes with fluctuations in moisture content, pose challenges in civil engineering projects, particularly in regions with a high prevalence of such soils. The objective of this research is to assess the ability of cement-based materials to mitigate the detrimental effects of expansive soil on subgrade performance. Laboratory tests, including Atterberg’s limit, compaction test, unconfined compression strength test (curing at 0, 4, 7, 14, 28, 56, 90, 180 and 365 days), expansion ratio, free swell index and California bearing ratio (curing at 0, 7, 14 and 28 days) were conducted to evaluate the performance of various cementitious materials when mixed with expansive soil. This work focuses on the effect, of development of the strength properties of treated soils with varying percentages of cementitious material as 2%, 4%, 6% and 8% under varying curing times in comparison to other materials. The results demonstrate that the incorporation of cementitious materials significantly reduces soil swelling, increases the subgrade’s shear strength and enhances its resistance to moisture-induced distress. The study delved into examining interactions occurring between the surface of the cementitious material and the soil matrix using field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, energy dispersive spectroscopy and x-ray fluorescence analysis. Furthermore, environmental sustainability of these stabilizers is discussed, considering their potential to mitigate the detrimental effects of expansive soils.