Effects of Specimen Heights on Fracture Process of Concrete Using DIC Technique

The effects of specimen heights on the fracture behaviors of concrete were studied by using the digital image correlation (DIC) technique. Three‐point bending tests on notched specimens with a constraint span but different depths were carried out. The horizontal strain field, horizontal displacement field, crack opening displacement ( COD ) evolution, crack extension length, and fracture process zone (FPZ) evolution were discussed. The results indicated that the FPZ width was proposed to be determined from the horizontal strain field with the measured value of 19.397 mm, which was consistent with the calculated result. Higher crack propagation speed was observed at the post‐peak stage. The obtained maximum value of FPZ length increased by 148.1% when the specimen height increased from 100 mm to 300 mm. Moreover, good agreement was observed between the evolution of the FPZ characterized by the DIC technique and the analytical approaches.