INTERFACE BEHAVIOR IN STEEL FIBER CEMENT COMPOSITES UNDER TENSION/

The fundamental properties of fiber-matrix interface are commonly dete rmined by analyzing fiber pullout tests. Recognition of the dependence of the interface properties on the explanation of the pullout force-d isplacement curve has motivated a recent study on using special techni ques to directly measure parameters relating to interface properties. In this paper, laser Moire interferometry was employed to study interf ace shear stress and interface energy release rate in continuous steel fiber-reinforced cementitious composites under tension in order to ev aluate the fiber-matrix interface response, which was primarily acquir ed from fiber pullout tests. It was observed that the maximum interfac e shear stress in the debonded zone was independent of fiber volume fr action, fiber diameter, and applied tensile load. The interface fricti onal shear stress decreased with increasing slip. The interface strain energy release rate measured using the continuous fibers was larger t han those obtained from short fiber pullout tests. The values of the i nterface energy release were dependent on fiber volume fraction and di ameter. This dependency can be well described by an R-curve approach.