Effects of water content on fracture and mechanical behavior of sandstone with a low clay mineral content

This study investigated the effect of water content on quasi-static fracture behavior of sandstone. Notched semi-circular bending (NSCB) tests were conducted on a total number of 20 sandstone specimens with different water contents (0, 1.0, 2.0 and 3.5%) to determine their fracture toughness. During the NSCB tests, the cracking process and acoustic emission (AE) signals were recorded continuously with the aid of a charged couple discharge (CCD) camera and an AE system, and the crack propagation velocity was also measured accurately via a crack propagation gauge (CPG). Test results demonstrated that both the fracture toughness and crack propagation velocity observably decreased with the increase of water content, the variation trend of which could be described by exponential equations. The cumulative AE counts of wet specimens in the NSCB tests were much less than those of dry ones, which indicated that the sandstone specimens underwent more ductile failure and released less elastic energy due to water-softening effects.