Fracture behaviour of high-strength concrete at a wide range of loading rates

Three-point bending tests on notched beams of a high-strength concrete have been conducted using both a servo-hydraulic machine and a self-designed drop-weight impact device. The fracture energy and the peak load were measured over a wide range of loading point displacement rates, spanning eight orders of magnitude. Under low displacement rates, from 10−4 to 10 mm/s, the tests were performed with the servo-hydraulic machine; from 102 to 103 mm/s we used the drop-weight impact machine. The results show that the fracture energy and the peak load increase as the loading rate increases. Nevertheless, such a trend is relatively slight under low rates and can be attributed to viscous effects mainly originating from the presence of water in the pore structure. Under high rates the increases in the fracture energy and in the peak load are dramatic due to the effect of inertia.