Some rocks are naturally weak, or it becomes weak due to weathering. Durability of weak rocks is one of the most important engineering properties to be evaluated. This study aims to determine the decrease of strength over time due to weathering processes for some weak rocks selected from four different locations within Nineveh. Rock samples were prepared for all types of selected rocks according to American Society for Testing Materials (ASTM) and International Society for Rock Mechanic (ISRM). Physical and mechanical properties of the samples were studied (dry density, absorption, Uniaxial compression test, Brazilian test, Point load test, and Slake–Durability test) in both dry and wet conditions. Slake - durability test used to determine the decrease in strength and weight loss% for studying rock samples using distilled water for all selected rock samples. Baghdad street and Talafare rocks samples were subject to a solution containing solute hydrochloric acid with 5%, and 10%, concentrations.
Results show that rock samples taken from Hay-AL-Quds and Hay-AL-Arab can be classified as very weak to weak with low durability, and weak with medium-high durability for samples selected from Baghdad street and Talafar. Results also indicate that there is a reduction in strength of treated rocks due to an increase in the level of weathering of rock. Higher values of reduction pointed out for samples treated with solute hydrochloric acid compared with the case when using distilled water with less effect in 5% concentration than that 10% concentration.