Changes on diametral compression behaviour of compacted marls due to drying

Abstract

Cracking due to desiccation can compromise the behaviour of earth structures built with compacted clayey soils by promoting water access and consequent volume changes on further wetting. Tensile strength therefore is important to be considered when studying the behaviour of such structures, and in particular its dependence on the degree of saturation or water content. The influence of water content in tensile behaviour of compacted marls was investigated by performing diametral compression tests (Brazilian splitting tests), where axial deformations were measured besides strength. The samples were prepared by compaction at optimum point using standard compaction energy (optimum water content 16%) and then dried by vapour equilibrium to reach water contents between 5% and 16%. The correspondence between water content and suction was done by using the drying branch of the water retention curve, measured using WP4 equipment (Water Dewpoint Potentiometer). Good relationships were found between tensile strength and the water content (and suction). In addition, the study was completed with the analysis of other parameters such as the semi-contact angle created in the loaded area and the stiffness of the material, which also showed changes with water content.