Assessment of granitic rocks degradability susceptive to acid solutions in urban area

Abstract

Granitic rocks have been used in wide range of studies. When using these rocks, the most important aspect to be considered is their weathering potential, especially in acidic and wet environments. In these conditions, acid rainfall that is generated from atmospheric pollutions can accelerate the weathering trend of these rocks. The aim of this article is to assess the relationship between the weathering processes and environmental conditions. For this purpose, four types of Alvand granitic rocks were collected. Then, using optical microscopy and X-ray diffractometry the textural and mineral compositions of the rocks were studied. As the second step, the physical properties of these rocks were determined. To assess the effect of pH on the degradability of rocks, three solutions with different pH were prepared by adding sulfuric acid. Finally, slake durability test for each type in sulfuric acid with pH 2.5, 4, and 5.5 up to 15 cycles was performed. The results indicated that these rocks posses a very high durability and their use as building stones are recommended. In spite of these facts, long-term effects such as the weathering process can cause serious problems to ancient buildings as in the inscription of Darius.