Intrinsic Compressibility of Laterites and Lateritic Soils

Abstract

Laterites and lateritic soils, prevalent in tropical and subtropical climates, have growing applications in earthwork construction. They usually present unique compression properties compared to conventional clays. Therefore, a thorough understanding of their intrinsic compressibility is crucial. This paper reports on modified oedometer tests conducted on reconstituted samples of four distinct laterites and lateritic soils with varying initial water contents. In addition, Scanning Electron Microscopy (SEM) was utilized to identify the microstructural features to reveal the mechanisms of intrinsic compression. The results demonstrate that intrinsic compression curves of reconstituted laterites and lateritic soils align with Burland's normalization framework. However, they exhibit a higher void ratio at an effective vertical stress of 100 kPa (e*100) and a lower compression index (C*c) compared to traditional clays; therefore, existing formulas for calculating e*100 and C*c are inapplicable to laterites and lateritic soils. The SEM analysis revealed that sesquioxide interacts with soil minerals, resulting in a porous structure and robust inter-unit cementation. This unique microstructure contributes to the observed intrinsic constants of compressibility. Based on the experimental observations, new empirical equations are introduced to evaluate e*100 and C*c in laterites and lateritic soils. The experimental results elucidate the role of sesquioxide in inherent compressibility.