Influence of aggregate morphological characteristics on the fracture resistance of high performance concrete

High-performance concrete (HPC) enables slender cross sections, lighter structures and wider spans for buildings characterised due to its advanced mechanical properties. These structures are often subjected to high cyclic loads. Despite being an advanced material, the opportunities that arise from the use of HPC under fatigue loading cannot be fully exploited because of conservative design standards. This could be mitigated by implementing fracture mechanical properties in structural analysis. In the following paper, the fracture behaviour of HPC is investigated using a modified compact tension test inside a computed tomography system. The tensile strength and fracture energy are measured. The fracture energy is of particular interest in this context as it is a key parameter in determining the damage laws of brittle materials. The morphological characteristics of aggregates and their mechanical interaction with the cement-based matrix strongly influence the crack formation and fracture behaviour of composite materials such as HPC. In order to identify the initial mesostructure comprising aggregate particles, cementitious matrix and air voids, a 3D image analysis technique based on computed tomography (CT) has been integrated. CT scans are performed under loading, and the 3D damage and crack propagation phenomena are quantitatively observed during the test. The static tests are carried out in displacement control and CT images are generated in predetermined displacement steps.