CRACK-ARREST IN MORTAR MATRIX REINFORCED WITH UNIDIRECTIONALLY ALIGNED FIBERS

This paper presents an investigation on the effects of reinforcement s ize, reinforcement spacing and specimen size on the fracture parameter s of notched mortar specimens reinforced with long aligned steel fiber s. A total of 33 specimens of variable fiber size, fiber spacing and s pecimen size were tested under quasistatic monotonic and cyclic loadin g conditions. For a constant volume fraction of steel reinforcement, t he experimental results indicate an increase in the fracture energy as the size of the reinforcing fibers and the corresponding spacing betw een the fibers is reduced. Finite element analysis indicates that the closing pressures imposed by the bridging of the fibers in the wake of the crack-tip increase as the spacing between the fibers is decreased , particularly as the spacing approaches approximately 6.25 mm. Within the resting range, the fracture energy (G(F)), energy release rate (G (1c)) and stress intensity factor (K-1c) appear to be independent of t he specimen thickness.