Degradation Characteristics and Mechanism of Black Sandy Dolostone Subjected to Wetting-Drying Cycles

The cyclic wetting-drying (W-D) effect as a typical form of weathering causes the engineering properties of rock degradation. Unlike previous research on soft sedimentary rocks, this study sought to investigate the influence of W-D cycles on the physical and mechanical properties of the black sandy dolostone. The results show that the surface hardness and uniaxial compressive strength decreased by 1.5% and 17.2%, respectively, after 12 W-D cycles. The behavior of water absorption of dolostone showed a logarithmic growth with W-D cycles. Analysis of the pH and electrical conductivity values of the soaking solution and microstructure of dolostone revealed that carbonate mineral and feldspar dissolution was the major reason to result in the increase in pore volume and micro-fissure. The oxidation of pyrite contained in the rock was deduced to accelerate the chemical reaction and rock degradation. The obtained results are expected to provide engineering values for rock mechanics studies when compared with in situ conditions.