T.Cheema - Department of Earth Sciences, Sultan Qaboos University, Muscat (Sultanate of Oman)
M.Al-Aghbari - College of Engineering, Sultan Qaboos University, Muscat (Sultanate of Oman)

In order to investigate the influence of grain size and mineralogy on the strength of weak rocks, eleven samples of weak rocks were collected from different areas of Muscat,Sultanate of Oman. Grain size properties included the effective particle size diameter and the clay content. The behavior of clay and other minerals was studied with the help of Atterberg limits and XRD. Point load index, slake durability, cohesion and friction angle were taken as a measure of strength. The results indicate that grain-size can be correlated with the strength. A decrease in clay content and D10 resulted in higher strength values. The presence of quartz was not found to influence the angle of friction.However, slake durability of the weak rocks was significantly increased by the presence of quartz.

Mudrock, rock compression strength, grain size mineralogy