Abstract:Three fly ash(FA) contents were selected to form three types of polyvinyl alcohol(PVA) fiber reinforced cementitious composites(PFRCCs). Three point bending test was implemented to evaluate the bending properties of PFRCC; SEM micrographs of PVA fiber surface, embedded and ruptured or pullout end of fiber in fracture surface were used to investigate PVA fiber matrix interface microstructure so as to reveal the process of PVA fiber bridging cracks; PVA fibers distribution was quantitatively measured by the fluorescence images on polishing surface of PFRCC sample. The test results show that the degree of PVA fibers reinforcing and toughening increases when adding FA. Moreover, the degree is remarkably improved when adding high content of FA; PVA fibers bridging stress in cracks and PVA fiber matrix interface bonding ability decrease with adding FA. Along with the expansion of cracks, PVA fibers bridging cracks changes from short slippage to long slippage, with the result that the efficiency of PVA fibers bridging cracks is significantly improved and the effect of fiber reinforcing and toughening is increased. The uniform cementious matrix formation due to FA addition leads to good fiber distribution, which promotes bending strength and toughness of PFRCC.
