Performance Evaluation of Nano-Stabilized Expansive Soils Using Laboratory Testing

Expansive soils are one of the most widely considered problematic soils and are characterized by high montmorillonite content, significant swell–shrink behavior, and severe volumetric changes with moisture variation. These soils cause significant structural damages globally, especially in dry and semi-arid areas. Nanomaterials have been shown to be one of the best and most advanced ways to stabilize soil. This study uses a comprehensive laboratory testing program to examine effectiveness of nanosilica as a stabilizer for expansive soil. The natural soil had a liquid limit of 56.2% and a plasticity index of 29.9%, and categorized as CH by USCS and A-7-6 by AASHTO classification systems. Nanosilica was incorporated at 0.5%, 1.0%, and 1.5% (dry weight) to assess its influence on the physio-mechanical properties of the soil. According to test results, considerable improvement in volumetric stability was observed by adding up to 1.5% nanosilica. The expansion index's decreased from 92.5 to 48.5. The engineering properties gradually improved with the addition of nanosilica. According to direct shear testing, Cohesion and friction angle increased from 32.3 kpa to 62.8 kpa and from 1.10° to 3.14°, respectively. Similarly, unconfined compressive strength increased from 98 kpa to 141 kpa.