The Impact of Mechanical Weathering on the Durability Strength Index of Ayer Hitam Shale Under Various Weathering Grades and Conditions

Abstract

Shale is significantly weaker and less durable than other types of rock and is easy to break when it is exposed to continuous wetting and drying activities. As a construction material, the durability strength index of weathered shale in Ayer Hitam, Johor, Malaysia is poorly investigated and not well understood. The purpose of this study is to investigate the effect of mechanical weathering on the durability strength index of Ayer Hitam weathered shale under several different conditions. Three hundred sixty samples of weathered shale which are classified as weathering grade II to IV were tested within the fifth cycles of the slake durability test under three different conditions namely: Natural weathering, dry, and saturated sample. The results showed that the weathered shale with the highest moisture content of 27.78% and the lowest strength index with 1% after the fifth cycle at week 8 was the weathering grade IV under saturated condition. It was also found that the reduction in the durability strength index was more than 90% with increased moisture content and weathering grades. In conclusion, the durability strength index of shale depends upon the number of cycles or weathering grade, duration of water immersion as well as moisture content.