CRACK-PROPAGATION IN FIBER-REINFORCED CONCRETE

A fracture mechanics-based theoretical model is presented to predict the crack propagation resistance of fiber-reinforced cement-based composites. Mode I crack propagation and steel fibers are treated in the proposed model. The mechanism of fracture resistance for fiber-reinforced concrete can be separated as: Subcritical crack growth in the matrix and the beginning of the fiber bridging effect; post-critical crack growth in the matrix such that the net stress intensity factor due to the applied load and the fiber-bridging closing stresses remains constant; and a final stage where the resistance to crack separation is provided exclusively by fibers. The response of fiber-reinforced concrete during all these stages was successfully predicted from the knowledge of matrix fracture properties and the pull-out load versus slip relationship of single fiber. The model was verified with the results of experiments conducted on notched beams reported here as well as by other researchers. Beams were loaded in a closed-loop testing machine in order to maintain a constant rate of crack mouth opening displacement. © 1986 American Society of Civil Engineers (ASCE). All rights reserved.