The effects of water acidity and engineering properties on rock durability

Abstract

Fifteen sedimentary rock samples of four rock types including sandstone, limestone, travertine and conglomerate were collected from Damghan area, northern Iran. Mineralogical studies and laboratory experiments were performed to assess physical properties, Schmidt hardness, P-wave velocity, slake-durability index, uniaxial compressive, point load, Brazilian tensile and block punch strengths of the rocks. 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 pH. The utilized test fluids were natural water with 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 pH of the test fluids. Also, the different rock types had distinctive slaking behaviors. Decreasing rate of slake-durability index at initial cycles is higher than the end cycles the same as weight loss rate of the specimens. 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 closely related to strength parameters of the rocks. This led to extraction of empirical equations for determining essential characteristics of the rocks from the slake-durability index.