Dissolution behavior of carbonate rocks under various physicochemical conditions: a case study; the Taleh Zang Formation, West of Iran

Carbonate rocks, widely exposed in SW Iran, display a variety of landforms on which many engineering projects including but not limited to, dams and water transfer tunnels are constructed. Considering the vulnerability of carbonate rocks to karstification, it is profoundly important to evaluate the dissolution behavior of these rocks before the beginning of construction phase. In this study, the dissolution behavior of the Taleh Zang Formation (widely exposed in the Kermanshah province, west of Iran) under different pH, temperature, and hydrodynamic pressure was evaluated. The dissolution tests were performed employing an especially designed testing apparatus. The petrographic characteristics of the samples were examined on thin sections; Observations showed that the carbonate samples are mainly composed of calcite with packstone texture. XRF analyses identified CaO is the predominant constituent. 18 dissolution tests were performed on cylindrical samples, 82 mm in diameter and a length range of 130–150 mm, drilled from the Taleh Zang rock blocks. The arranged dissolution tests were then performed in four stages of hydrodynamic pressures (0.5, 0.7, 1.2, 1.7 bar), two pH ranges (pH = 5.5 and 6.0), and two temperature setpoints (7.5–9.0 °C and 14.5–15.5 °C). Results showed that the first parameter imparted considerable impact on the total weight loss of test samples. It was observed that water pH alteration would considerably affect the the hydrodynamic pressure activity. At last, seemingly, water temperature had the smallest share of impact on the dissolution behavior of the samples.