Influence of suction on the dilatancy of an unsaturated lateritic sandy lean clay

Lateritic soil covers about 15% of the area in the world and is extensively used as fill materials in various applications, such as back-filling materials for retaining structures and pavements. Lateritic soil is uniquely recognized for its rich composition in oxides of iron and aluminium (sesquioxide), which enhance the formation of soil aggregates. The responses of these aggregates under hydro-mechanical loading can significantly affect the volume change and shear strength of the soil. Lateritic soil is less studied, and
there has been limited laboratory data reported in literature to explicitly illustrate how suction affects its shear strength and dilatancy.
Therefore, a good understanding of their hydro-mechanical behaviour is required because it can improve the designs of civil engineering structures built on lateritic soils. In this paper, a series of laboratory tests on a compacted lateritic sandy clay (LAT) were carried out in a suction-controlled triaxial apparatus. Three different suctions (0, 50 and 150 kPa) were considered. Each specimen was wetted from initial suction of 150 kPa to the desired suction before isotropic consolidation and constant suction shearing. During shear, each specimen was subjected to a constant net stress and suction. Effects of soil suction on the evolution of dilatancy, stress dilatancy relationship and maximum dilatancy will be reported and discussed in this paper.