Fracture behaviour of polypropylene-fibre-reinforced concrete under biaxial loading: An experimental investigation

Polypropylene-fibre-reinforced concretes (FRC) with different fibre lengths and fibre contents were tested under uniaxial tensile stress and biaxial (combined tension compression) stress. The tests were carried out on notched cube samples in a wedge splitting test jig that could be varied such that biaxial loading experiments were possible. Load/displacement curves were measured with stable crack propagation. From these curves typical fracture parameters were established in order to characterize the fracture behaviour of FRC completely, and the influences of different fibre lengths and fibre contents were determined. The most important fracture processes in front of and behind the crack tip were analysed and discussed when FRC was broken under the same biaxial load. By means of a simple model the fracture behaviour and the influence of fibre length and fibre content on the established parameters of fracture could be explained qualitatively. Finally some aspects of biaxial fracture in FRC, which are of interest for engineers, are discussed.