Experimental study of sulfate crystallization damage to glutenite rock in the Maijishan Grottoes

Abstract

AbstractSalt crystallization is one of the most important factors causing weathering in grottoes. Cumulative crystallization of salts causes damage such as flaking and peeling of the rocks and accelerates the weathering processes of the grottoes. The accumulated crystalline salts cause spalling, skinning and other damage and accelerate the weathering process of the grotto rock body. It is necessary to study the existing glutenite rock grottoes. This paper took the glutenite rock of the Maijishan Grottoes as a case study, and Na2SO4 or MgSO4 solutions were applied to glutenite rock specimens subjected to different deterioration cycles. The crystallization patterns of the two different salts and their damage to the glutenite rock were analyzed and studied, the mechanism for salt crystallization damage to the glutenite rock was explored, and the crystallization pressures of the two salts in the glutenite rock were derived with theoretical calculations. The results showed that both Na2SO4 and MgSO4 crystallization damaged the glutenite rock, and the former different sulfate solutions changed at different rates, and the changes in the wave caused faster damage than the latter. The physical indices of the rock samples in the velocities and tensile strengths were consistent. Na2SO4 was mainly accumulated on the surface of the specimen and damaged the glutenite rock centripetally via pulverization and exfoliation. MgSO4 mainly crystallized inside the glutenite rock, which created internal fissures and reduced the strength of the rock. The theoretical maximum crystallization pressures of Na2SO4 and MgSO4 in the glutenite rock specimens reached 33.00 MPa and 9.94 MPa, respectively. This study provides a theoretical basis for studies of salt crystallization in glutenite rock grottoes and provides a method for protecting the stones in cultural heritage sites against weathering.