Compressibility and microstructure of compacted lateritic clay at different suction levels

Abstract

Many construction projects worldwide commonly utilize lateritic clays as essential construction materials. These soils require a specific knowledge of their physical and mechanical properties. In this work, scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and matrix suction measurements were conducted on lateritic clay. The purpose was to obtain soil water characteristic curves (SWCC) and the influence of suction on the stress–strain behavior of compacted specimens of lateritic clay under zero lateral displacement conditions. The results show that lateritic clay compacted on the dry and wet side of the compaction curve has dual porosity. The mean micropore size is near 19 nm, while macropores have mean sizes of 2.1 μm, 8.4 μm, and 5.4 μm when the specimens are compacted in the dry, optimum, and wet side of the compaction curve, respectively. Also, the SWCC curve has a bimodal shape, in agreement with the MIP results. Matrix suction and the microstructure generated during compaction significantly influence the stiffness of the compacted lateritic clay. The compacted lateritic soil shows stiffening as water content decreases at 800 kPa of 5.95%, 5.3%, and 2.93% for the specimens compacted on the wet, optimum, and dry side of the compaction curve.