An Investigation on Dissolution and Deterioration of Building Stones in Sulfuric and Nitric Acids Solutions

Acid rain is one of problems due to air pollution. In areas with polluted atmosphere, SO4 and NO3 are among most important contaminator, which constitutes sulfuric and nitric acids solutions, as a result of combining with hydrogen ions. Also, these solutions are among important agents in building stones dissolution and deterioration. Regarding the involved acid and its pH, these solutions have different effects on stones. In this research, we selected 14 building stones samples of different origins. Then, in order to investigate their dissolution and deterioration and, also comparing sulfuric and nitric acids dissolving effect, we performed Durability Test up to 15 cycles, and calculated Durability Index on mentioned solutions - with pH = 1.5, 3, and 5, and also fresh water with pH = 7.3. The results show that the samples with non-carbonate composition are resistant against those acids, while the carbonate ones are not. Furthermore, comparing results of Durability Index indicates that sulfuric acid has 0.06 to 0.93% greater dissolving effect than nitric acid. In addition to, a decrease in both acids pH, leads to a greater dissolution of carbonate samples. Finally, according to obtained results, we recommended the most suitable stones for exterior façade of buildings.