Effect of microstructure on load-carrying and energy-dissipation capacities of UHPC

The load-carrying and energy dissipation capacities of ultra-high performance concrete (UHPC) under dynamic loading are evaluated in relation to microstructure composition at strain rates on the order of 105 s− 1 and pressures of up to 10 GPa. Analysis focuses on deformation and failure mechanisms at the mesostructural level. A cohesive finite element framework that allows explicit account of constituent phases, interfaces, and fracture is used. Three modes of energy dissipation are tracked, i.e., inelastic deformation, distributed cracking, and interfacial friction. Simulations are carried out over a range of volume fractions of constituent phases. Results show that (1) volume fractions of the constituents have more influence on the energy-dissipation than load-carrying capacity, (2) inelastic deformation is the source of over 70% of the energy dissipation, and (3) the presence of porosity changes the role of fibers in the dissipation process. Microstructure–behavior relations are established to facilitate materials design for target-specific applications.