Fracture properties of concrete through DIC analysis of the largest dataset on size effect

This study uses digital image correlation (DIC) data to analyze the fracture behavior of plain concrete notched beams of five different depths (75 mm, 150 mm, 250 mm, 500 mm, 1000 mm), tested in a three-point-bending (TPB) configuration. The fracture energy of concrete is determined from the load versus load-point displacement (LPD) responses of the notched beams. Differences in fracture energy using LPD measurements from linear variable differential transformers (LVDTs) and DIC are discussed. The concept of fracture process zone (FPZ) is associated with the softening behavior of concrete described by the cohesive crack model. FPZ length and width are studied by analyzing DIC full-field displacement and strain data. The variation of these parameters with increasing specimen depth is discussed in the context of the well-known size effect phenomenon. Furthermore, a novel approach to determine critical crack opening w f , using DIC data, is proposed by the authors. The evolution of w f and FPZ length along the notch ligament is evaluated for different load levels.