An investigation of fracture initiation and resistance-curve behavior in concrete

This paper examines the effects of mix strength on the fracture initiation and resistance-curve behavior of concrete. The fracture initiation toughness and the resistance-curve behavior are shown to increase with increasing mix strength. However, the extent of stable crack growth is shown to decrease with increasing mix strength. The measured resistance-curve behavior is associated with the beneficial effects of crack-tip shielding due to ligament bridging mechanisms. The observed small- and large-scale bridging phenomena are then modeled using fracture mechanics models. The studies show that the measured resistance-curve behavior is predicted largely by considering the beneficial effects of ligament bridging. Finally, the implications of the results are then discussed for the design of durable concrete structures.