Evolution of disintegration properties of granite residual soil with microstructure alteration due to wetting and drying cycles

Despite extensive investigations of the disintegration behavior of rock, much less is known about the disintegration behavior of residual soil derived from the weathering of the parent rock. The engineering geology of RS is widely recognized as being associated with the parent rock properties as well as the weathering conditions. In the case of granite residual soil, how climate changes affect its disintegration behavior is currently not well understood. This paper performed laboratory disintegration tests on natural and remolded GRS as well as the residual soil subjected to various wetting–drying (W–D) cycles. The soil microstructure alterations due to W–D cycles are also investigated through scanning electron microscope and mercury intrusion porosimetry. The W–D cycles transform the microstructure of natural GRS toward the pattern for remolded soil by damaging the cementation among soil particles, expanding the pore diameter, and forming macropores and fissures. The deterioration of cementation weakens the particle association; thus, the soil is more disintegrative, and the generation of fissures facilitates this water–soil interaction by allowing infiltrating water to pass through. Several parameters are proposed to quantify the microstructure alterations and are found to correlate well with the disintegration rates of soil subjected to W–D cycles. This paper quantifies the microstructure evolution as induced by W–D cycles and enhances the understanding of the mechanism for the disintegration of residual soil.