Synergestic effect of rice husk ash blended with cement on the stabilization of lateritic soil for road construction

Abstract

Lateritic soils are widespread in tropical regions and are often unsuitable for direct application in road construction due to high plasticity and low strength. The extensive use of Portland cement for soil stabilization has raised concerns over rising construction costs and environmental degradation caused by CO? emissions. This study examined the effect of stabilizing lateritic soil using Rice Husk Ash (RHA) blended with Ordinary Portland Cement (OPC), focusing on highway engineering applications. Natural lateritic soil samples were collected and treated with varying blends of cement (5%, 10%, and 15%) and RHA (2% to 10%) by dry weight. Standard geotechnical tests including Atterberg limits, compaction, California Bearing Ratio (CBR), and Unconfined Compressive Strength (UCS) were carried out to evaluate improvements. Furthermore, the chemical and microstructural properties of RHA and treated soil were analyzed using X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). Results showed a notable improvement in geotechnical performance. The liquid limit dropped from 31.5% to 25%, the plastic limit dropped from 29.2% to 25%, and the plasticity index declined from 3.5% to 0%. Maximum Dry Density (MDD) rose from 1.84 g/cm³ to 1.96 g/cm³, while Optimum Moisture Content (OMC) decreased from 7.95% to 10.81%. The unsoaked CBR value increased from 76% to 94%, and UCS improved from 186 kN/m² to 334 kN/m² at an optimal mix of 10% cement and 10% RHA. RHA-cement stabilization significantly enhances the geotechnical properties of lateritic soils. This eco-friendly approach is recommended for sustainable and cost-effective road construction.