A New Rapid Method to Assess the Durability of Shale

Abstract

Shale is the most abundant sedimentary rock worldwide and is often used as a construction material in many civil engineering applications. However, this material is easily deteriorated when it is exposed to cyclic wetting and drying processes. Deterioration of shale used for highway construction applications may lead to bearing capacity failure of highway embankments and instability of the adjacent slopes. The susceptibility of shale to deterioration is typically quantified by durability. In this context, durability is a measure of the rate and magnitude of deterioration and is used to describe the susceptibility of a material to environmental factors such as mechanical and chemical weathering. The Jar Slake test is a visual observation-based immersion test used to qualitatively assess the durability of shale. Although the test is relatively rapid and easy to perform, the results are very subjective. This paper presents a new method that utilizes the immersion aspect of the Jar Slake test, which simulates water-induced deterioration of shale. However, the proposed method eliminates the subjectivity associated with the Jar Slake test. The proposed method quantifies the durability of shale using time dependent changes in electrical conductivity measurements of a shale-water solution. In this method, there is only need to monitor the electrical conductivity of the shale-water solution for up to 60 min and predict the durability of the shale by a simple model developed from this study. The results of the proposed method were found to compare well with other more rigorous methods to assess durability.