Utilization of Nano Silica and Plantain Leaf Ash for Improving Strength Properties of Expansive Soil

This study investigates the effect of nanosilica and plantain leaf ash on the sustainable stabilization of expansive soil. This study conducted various strength tests, including Unconfined Compressive Strength (UCS), direct shear, and California Bearing Ratio (CBR) tests, to analyze the enhancement of mechanical properties by adding nano silica and plantain leaf ash. Scanning Electron Microscopy (SEM) analysis was conducted to investigate the interaction mechanism between the soil and the combination of nano silica and plantain leaf ash. Three different combinations of plantain leaf ash were utilized, ranging from 5% to 15%, alongside nano silica ranging from 0.4% to 1.2%. The reinforced soil’s compressive strength, shear strength, and bearing capacity were assessed through UCS, direct shear, and CBR tests. The results demonstrated significant improvements in compressive strength, up to 4.6 times, and enhancements in cohesion and frictional angle, up to 3.3 and 1.6 times, respectively, at 28 days. Moreover, the addition of nano silica and plantain leaf ash led to increased bearing capacity and reduced soil swelling potential, contributing to the overall stability and strength improvement in expansive soil. The SEM test results demonstrate that maximum bonding and compaction occur when 1.2% nano silica and 15% plantain leaf ash are added to the soil.