SUSTAINABLE SOFT CLAY STABILIZATION USING RICE HUSK ASH AND WASTE SPENT CATALYST FROM RESIDUAL CATALYTIC CRACKING

Abstract

The chemical stabilization of soft clay aims to improve its bearing capacity, enabling it to support structural loads effectively. This study investigates the effectiveness of Rice Husk Ash (RHA) and Spent Catalyst RCC 15 (RCC) as stabilizing agents. The research begins with soil sampling and index property analysis, followed by engineering tests to evaluate the Unconfined Compressive Strength (UCS), Atterberg limits, and compaction characteristics. The stabilization mixtures were composed of 6% RHA, with RCC 15 varying at 5%, 7%, 9%, and 11%. The Plasticity Index (PI) decreased from 29.45% to 25.55% with increasing RCC 15 content, indicating reduced plasticity and improved stability due to pozzolanic cementation. The compaction test results show that the Maximum Dry Density (MDD) increased to 1.355 g/cm³, while the Optimum Moisture Content (OMC) decreased to 25.67%, demonstrating improved densification. UCS testing revealed a significant strength increase, with the highest compressive strength of 0.217 MPa (2.17 kg/cm²) achieved at 6% RHA and 11% RCC 15, marking a 4.4-fold improvement over untreated soil. These findings confirm that RHA and RCC 15 significantly enhance the strength, density, and plasticity characteristics of soft clay, making them viable alternatives for soil stabilization. The study highlights the sustainability benefits of using industrial byproducts in geotechnical applications, reducing dependence on conventional materials while enhancing soil performance.