Micromechanics of fiber-reinforced cementitious composites

The strain hardening and tension softening response of short fiber-reinforc ed cementitious composites under unidirectional tensile/flexural loading is modelled using concepts from fracture and damage mechanics. The tensile st rain hardening in these composites is due to the formation of microcracks w hich ave however prevented from coalescing by the bridging action of the fi bers. The density of microcracks increases with increasing tensile/flexural loading until it reaches a saturation level at the tensile load carrying c apacity of the composite. Thereafter the fibers progressively debond from t he elastic matrix and the deformation begins to localise in the eventual fr acture plane, first as unconnected cracks and later as a connected through crack subjected to the residual frictional bridging action by the fibers.