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.