Experimental investigation on the mechanical behavior of red sandstone under the coupled effects of temperature and acidic etching

The red sandstone that commonly exists in nature is used to study the coupled effects of temperature and acidic etching on its mechanical properties. The dry-wet cycle is adopted to accelerate the corrosion process during the test, and the increase in the number of dry-wet cycle indicates the increase of the degree of corrosion. A series of uniaxial compression tests were carried out, and the influence of dry-wet cycle times on the physical and mechanical properties of red sandstones was analyzed. Besides, the crack propagation, phase composition, and the micromorphology of red sandstone were analyzed by means of acoustic emission (AE), X-ray diffraction (XRD), and scanning electron microscope (SEM). The results show that the physical and mechanical parameters of red sandstone such as the P-wave velocity and the uniaxial compressive strength have been deteriorated in different degrees considering coupled effects of temperature and acidic etching. With the increase of the number of dry-wet cycle times, the elastic deformation section of the axial stress-strain curve of the specimen becomes shorter and the softening characteristic is gradually obvious. The evolution of AE is a good evidence for the changes of internal structure of the specimen due to the coupled effects of temperature and acidic etching. The results of the XRD and the SEM indicate that the species of minerals increase and the microstructures of the specimen were changed with the increase in the number of dry-wet cycles.