Limestone Deterioration Under Freeze–Thaw and Acid Attack: A Critical Geotechnical Problem for the Stability of a Structure Foundation (A Case from Lorestan Province, Iran)

The Sakhrei Hotel, located in Khorramabad city (Lorestan Province, western Iran), is a civil structure under construction on a limestone foundation. Considering the occurrence of freeze–thaw (FT) and acid attack (AA) in Khorramabad, an in-depth study is required to evaluate the durability of limestone against these deterioration processes. To this end, the FT and AA tests were conducted on specimens prepared from a limestone under separate and combined conditions. The specimens were subjected to the FT test (in both distilled water and an H₂SO₄ solution with a pH 4) and the AA test (in an H₂SO₄ solution with a pH 4) for up to 80 cycles. After every 10 cycles, physico-mechanical characteristics of the specimens, including porosity (n), point load index (PLI), Brazilian tensile strength (BTS), uniaxial compressive strength (UCS), modulus of elasticity (E), and P-wave velocity (Vp), were measured. The results showed that the FT test in H₂SO₄ solution had the highest adverse effects on the deterioration of the limestone, followed by the AA test and FT test in distilled water. These findings are in good agreement with the scanning electron microscopy (SEM) images obtained from the deteriorated limestone subjected to FT and AA. Also, the results revealed the lower accuracy of the PLI than n, BTS, UCS, E, and Vp for evaluating the limestone durability against FT and AA for both conditions, acting separately and in combination. Finally, the data analysis of the FT and AA tests indicated that limestone quality can be adversely affected over time due to the deterioration of its physico-mechanical characteristics.