Fracture Mechanics Parameters of Fine Grained Concrete with Polypropylene Fibres

Fracture mechanics is widely used to analyze the material behaviour in a structure. The paper reports the results of an experimental programme focused on the effect of various synthetic fibres on the fracture properties of concrete investigated in Mode I conditions. The changes in concrete properties were analysed on the basis of the critical stress intensity factor KIc, the critical value of crack tip opening displacement (CTODc) and the fracture energy GF. The addition of the synthetic fibres had a slight effect on the strength properties of concrete but, at the same time, it had a significant influence on the fracture mechanics parameters by the modification of pre-cracking and particularly post-cracking behaviour of the concrete. Results of measuring the toughness and energy-absorption characteristics showed that the specimens reinforced with synthetic fibres acquired a great ductile behaviour and energy absorption capacity, compared to ordinary concrete specimens.