Mudstone is a kind of fine-grained, clay-rich sedimentary rocks. It commonly forms the natural ground on construction sites and may also be encountered as construction materials. Due to its composition and structure, mudstone can be susceptible to water content changes. It can disintegrate after drying and wetting cycles, which is known as “slaking”. In this study, a series of laboratory tests were conducted to investigate the slaking properties of mudstone obtained from a site in Hokuriku region, Japan. In previous study, it was found the mudstone can rapid breakdown in water after only one drying-wetting cycle. Hence, a specific slaking test method was newly proposed, in which the specimens were dried using the vapor equilibration method to control its suction. After that, CU triaxial compression tests were also conducted on undisturbed mudstone, remoulded mudstone and mudstone after slaking to investigate the changes in mechanical properties of mudstone before and after slaking. According to the experimental results, slaking of the mudstone tended to become more pronounced as the suction increased. In the CU tests, the mudstone that underwent one drying-wetting cycle exhibited a significant decrease in critical stress ratio and overconsolidation effect.
 

mudstone,slaking,triaxial test,unsaturated soil