Interface behavior in steel fiber/cement composites under tension

The fundamental properties of fiber-matrix interface are commonly determined by analyzing fiber pullout tests. Recognition of the dependence of the interface properties on the explanation of the pullout force-displacement curve has motivated a recent study on using special techniques to directly measure parameters relating to interface properties. In this paper, laser Moire interferometry was employed to study interface shear stress and interface energy release rate in continuous steel fiber-reinforced cementitious composites under tension in order to evaluate the fiber-matrix interface response, which was primarily acquired from fiber pullout tests. It was observed that the maximum interface shear stress in the debonded zone was independent of fiber volume fraction, fiber diameter, and applied tensile load. The interface frictional shear stress decreased with increasing slip. The interface strain energy release rate measured using the continuous fibers was larger than those obtained from short fiber pullout tests. The values of the interface energy release were dependent on fiber volume fraction and diameter. This dependency can be well described by an R-curve approach.