1 College of Construction Engineering, Inner Mongolia Technical College of Construction, Hohhot 010070; 2 College of Science, Inner Mongolia University of Technology, Hohhot 010051; 3 College of Information Engineering, Inner Mongolia University of Technology, Hohhot 010051; 4 College of Civil Engineering, Inner Mongolia University of Technology, Hohhot 010051
Abstract: Three types of polyvinyl alcohol (PVA) fiber reinforced cementitious composites (PFRCC) were produced by adjusting water/binder(w/b) ratio. A single fiber pullout test was utilized to measure interface parameter (chemical debonding energy Gd and frictional bond strength τ0) between PVA fiber and cementitious matrix and found that the values of Gd and τ0 decrease when w/b increases. The values of bending toughness and strength of PFRCC was attained via three-point bending test. The effects of PVA fiber-matrix interface property on bending properties were evaluated based on interface analysis with the aid of the macro-image and SEM micrographs of PVA fibers morphology in the failure crack. The analysis results find out that a large number of fibers of the samples with low w/b in the final failure crack are instantly ruptured due to high strength in the crack and high chemical bond in the fiber-matrix interface, which leads to low bending toughness and low rate of improvement from crack strength to bending strength; the fibers of the samples with moderate w/b in the crack can debond and slide, but the morphology of the fibers are seriously scraped by frictional bond strength. While a large number of fibers of the samples with high w/b in the crack are pulled out due to low chemical bond and the pull-out fibers are slightly scraped during sliding by low frictional bond strength. Therefore, the bridging fibers experience longer slippage and the samples are characterized by high bending deflection on a macro level, which results in high bending toughness value and high rate of strength improvement.
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2018, Vol. 32 
