Effect of Water on Shear Strength Parameter of Clay Shale

Clay shale is composed of clay, rock, and dust that has undergone a cementation process, has unique characteristics, namely being very hard when dry and very soft when wet. However, due to the exposed layers of clay shale, it also weathering due to continuous contact with air. This causes the failure of structures standing on clay shale. One of the parameters that affect the strength of clay shale is the shear strength parameter which can be carried out through direct shear and uncofined compression strength tests. In this study the addition of water content was applied to determine changes in the shear strength parameters of clay shale. Based on the results of the direct shear and unconfined compression strength test, it was found that with the addition of water content, the shear strength parameter of clay shale decreased. The addition of 100% water content causes the friction angel to be 18.93 o and the cohesion to be 11.95 kPa on the direct shear test. While the results of the unconfined compression strength test showed a decrease of 81.18% at the addition of 75% water content. The decrease in the shear strength parameter is due to the loss of bonds between particles.