Review of Clay Shale Soil and its Future Research

During the massive infrastructure construction in Indonesia, some of the infrastructures encountered many problems with clay shale soil. From several slope failures in clay shale formations, three main points were found. First, the type of slope failure was mainly translational. Second, slaking of clay shale reduced its shear strength and initiated failures. Third, a possibility of interface failure was found between the overburdened soil and the clay shale layer. From these characteristics, many studies were conducted mainly on the first two points. Thus, this research would like to summarize the existing research while also exploring the third possible point for clay shale slope failure. The discussion is limited to clay shale in Indonesia. Four main topics were categorized: engineering properties, weathering properties, shear strength properties, and interface behavior. First, engineering properties research showed that different locations of clay shale would have different characteristics. It would also help in determining its weathering properties and selecting the correct correlations. Second, the weathering properties indicated that smectite is a dominant mineral that affects the weathering of clay shale. It also showed that determining the weathering degree can use both the durability index and disintegration ratio. Third, the topic of clay shale shear strength is divided into residual shear strength determination and shear strength reduction due to weathering. Lastly, the interface shear strength research is still limited, but it is currently developing in many geotechnical engineering fields. Thus, it is a great prospect for interface shear strength of clay shale research.