Acid solution decreases the compressional wave velocity of sandstone from the Yungang Grottoes, Datong, China

Acidic solutions significantly degrade the structural integrity of sandstone from the Yungang Grottoes. Research shows that exposure to sulfuric (H₂SO₄) and nitric (HNO₃) acids at increasing concentrations leads to a marked decrease in compressional wave velocity, reduced compressive strength, and increased effective porosity—indicators of microstructural damage. Unlike water treatment, acid exposure alters the sandstone's chemical composition, complicating its structure post-weathering. The study highlights the potential deterioration risk posed by environmental pollutants like SO₂, NOₓ, and PM₂.₅, which form sulfates and nitrates, threatening the preservation of stone relics in the grottoes.

Geng, H., Zhang, S., Zhi, J., Zhang, R., Ren, J., & Ro, C.-U. (2019). Acid solution decreases the compressional wave velocity of sandstone from the Yungang Grottoes, Datong, China. Heritage Science, 7(1). https://doi.org/10.1186/s40494-019-0245-2