Sulfur dioxide (SO2) is one of the most hazardous pollutants in the atmospheres of industrial cities. This pollutant, in combination with rainfall, forms acid rain. Acid rain can affect the physico-mechanical properties of stones and decrease their durability over time. In this paper, the pH effect of sulfuric acid was investigated on the physico-mechanical properties of travertine, including porosity (n), point load index (PLI), and Brazilian tensile strength (BTS). For this purpose, a travertine sample was obtained from the Atashkuh quarry in Mahallat (central Iran). Next, 30 cycles of wetting and drying were performed on the sample in H2SO4 solutions with pH values of 2, 3.5, and 5, followed by measuring its physico-mechanical properties after every 5 cycles. Parameters of the decay constant (lambda) and half-time (N-1/2) were obtained from regression curves developed between the measured physico-mechanical properties and cycles of wetting and drying in H2SO4 solutions. The N-1/2 and the rate of loss (RL) these properties were used for comparing the effect of H2SO4 solutions with pH of 2, 3.5, and 5 on the sample. The results of data analysis showed that with an increase in the number of wetting and drying cycles in H2SO4, the n increased while PLI and BTS decreased with varying degrees. Furthermore, the variations in the physico-mechanical properties of the sample and their lambda and N-1/2 indicated that the durability of the sample changes after the interaction of the H2SO4 solution with various pH values.
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