Strength Assessment of Rice Husk Ash and Bentonite Stabilized Lateritic Soil for Landfill Liners

Abstract

This study investigates the strength behavior of lateritic soil stabilized with rice husk ash (RHA) and bentonite for potential application as landfill liners. Laboratory tests were conducted to evaluate the basic properties, compaction characteristics, and unconfined compressive strength (UCS) of the stabilized mixtures under varying compaction efforts (BSH, WAS, and BSL) and moisture conditions (dry of optimum, optimum, and wet of optimum). The stabilized mixtures were prepared by blending laterite with varying proportions of bentonite (0–12%) and fixed RHA contents at 8%. The lateritic soil was classified as highly plastic clay (CH), while bentonite exhibited high swelling capacity and RHA demonstrated significant pozzolanic potential due to its high silica content. Compaction results showed that maximum dry density (MDD) decreased with increasing bentonite content, while optimum moisture content (OMC) increased as a result of the high-water absorption of RHA and bentonite. UCS results revealed that only mixtures compacted under heavy (BSH) and intermediate (WAS) efforts, with 6–9% bentonite at 8% RHA, achieved the recommended UCS range of 200–400 kN/m² for landfill liners. Excess bentonite (12%), light compaction (BSL), and wet-of-optimum states significantly reduced strength due to increased void ratios and moisture-induced weakening. The findings highlight the suitability of RHA–bentonite stabilized lateritic soil as a cost effective liner material when optimized at appropriate binder content, compaction, and moisture conditions.