The fracture toughness of concrete under impact loading

Abstract The fracture toughness of plain concrete, high strength concrete, and concrete reinforced with fibrillated polypropylene fibers was studied. Single-edge notched beams, of dimensions (l×w×d) 1400×100×125 mm, were loaded dynamically in 3-point bending, using an instrumented drop weight impact machine. Fracture energies and dynamic fracture toughness (K ID ) values were determined, using three different drop heights of the impact hammer. It was found that, for all three types of concrete, K ID increased with increasing drop height; the fracture toughness values under impact loading were much higher than those obtained in static tests. There were also dramatic increases in the fracture energies under impact loading.