Study on the Average Fracture Energy for Crack Propagation in Concrete

Abstract

Fracture energy represents the average total energy consumption during a complete crack propagation process. The use of one fracture property, the RILEM fracture energy, on its own is not sufficient to characterize the fracture behavior during crack stable and unstable propagation periods. In this paper, two fracture energy quantities, the stable fracture energy and unstable fracture energy, are introduced to predict energy consumption for those two crack extension periods. Wedge splitting tests were carried out on concrete specimens with different ligament length to identify all three fracture energy quantities. The experimental results show that the stable fracture energy remains almost a constant irrespective of specimen size, while the unstable fracture energy increases with increasing ligament length. A similar size dependency is observed in the RILEM fracture energy. An explanation is offered for this size dependency by considering the boundary effect of the specimen.