Mode I and Mode II Granite Fractures after Distinct Thermal Shock Treatments

Abstract

In this study, the effect of thermal shock (TS) on the mechanical properties of granite is investigated. Two schemes are performed to provide different cooling rates for the TS processes. Decreasing trend of dry density and P-wave velocity with ascending TS temperatures are observed. The porosity has an increasing trend with ascending TS temperatures. The effects of TS on the mechanical responses are investigated through Brazilian tests on the granite specimens of the cracked straight through Brazilian disc (CSTBD) under Mode I and Mode II loading. Mode I and Mode II fracture toughness values are obtained according to the mechanical tests, and a power relation is proposed to fit the fracture toughness values with respect to TS temperatures. Scanning electron microscope (SEM) is adopted to observe the fracture surfaces of the TS-treated specimens after the tests. Distinct features such as intergranular fracture are identified on the fracture surface of a water-cooled specimen, which indicates material deterioration to a greater extent as compared with that of an air-cooled specimen.