Fracture Toughness for Steel Fiber‐Cement Paste Interfacial Zone

Abstract

The critical strain energy release rate for the interfacial zone is experimentally obtained by applying the compliance method to the single‐fiber pull‐out test. Effects of the embedded length and the addition of silica fume on the critical strain energy release rate are discussed. The microstructure of the interfacial zone is characterized by means of microhardness measurements. Correspondence between the critical strain energy release rate and the microstructures of the interfacial zone is also discussed. The formation of the dense microstructure in the interfacial zone due to the addition of silica fume does not always lead to the improvement of its critical strain energy release rate. On the contrary, the critical strain energy release rate for the interfacial zone is decreased by the addition of silica fume. It is concluded that the improvement of bond strength by the addition of silica fume is mainly due to the greater frictional resistance along the debonded interface.