The effects of water acidity and engineering properties on rock durability

Fifteen sedimentary rock samples from four rock types, including sandstone, limestone, travertine, and conglomerate, were collected from northern Iran???s Damghan area. Mineralogical studies and laboratory experiments were performed to assess the rocks??? physical properties, Schmidt hardness, P-wave velocity, slake-durability index, uniaxial compressive, point load, Brazilian tensile, and block punch strengths. The studied rock samples are mainly composed of quartz, calcite, and dolomite with different textures. The slake-durability test was carried out up to ten cycles in fluids with different pHs. The utilized test fluids were natural water with a pH of 7 and sulfuric acid solutions with pH of 5.5 and 4. Based on the results, the slake-durability index is affected by the pH of the test fluids. Also, the different rock types had distinctive slaking behaviors. The decreasing rate of the slake-durability index at initial cycles is higher than the end cycles. Regression analyses showed that the evaluated parameters are correlated to the slake-durability index. In other words, the slake-durability index of the studied rock samples is greatly affected by their mineral composition, texture, physical properties such as porosity, and it is closely related to the strength parameters of the rocks. These preliminary results led to the extraction of empirical equations for determining essential characteristics of the rocks from the slake-durability index.