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对3类不同粉煤灰掺量下形成的聚乙烯醇(PVA)纤维水泥基材料,通过三点弯曲试验测试,研究了PVA纤维水泥基材料的弯曲性能;通过对PVA纤维水泥基材料断裂面处纤维表面、纤维嵌入端和纤维拉断或拔出端的扫描电镜影像分析,研究了PVA纤维-(水泥)基体界面微观结构,揭示了PVA纤维桥接裂缝过程;通过PVA纤维水泥基材料样本抛光表面的荧光影像,量化测定了PVA纤维在基体中的分布.结果表明:掺入粉煤灰后PVA纤维对水泥基材料增强增韧作用增加,高掺量下效果更显著;掺入粉煤灰后裂缝处PVA纤维的桥接应力和纤维-基体界面黏结力降低,随着裂缝的扩展,PVA纤维由短距离滑动转变为长距离滑动,纤维桥接裂缝的效率提高,增强增韧的作用增加;掺入粉煤灰后基体结构更加均匀,PVA纤维分布系数增大,PVA纤维对水泥基材料的增强增韧作用提高.
The bending properties of PVA fiber cement-based materials were studied by three-point bending test on three types of polyvinyl alcohol (PVA) fiber cement-based materials formed at different fly ash contents. By analyzing the fracture surface of PVA fiber cement- The microstructure of PVA fiber - (cement) matrix interface was studied by scanning electron microscope (SEM) image analysis of fiber surface, fiber embedded end and fiber pull - out or pull - out end. The bridging crack process of PVA fiber was revealed. The PVA fiber cement - The results showed that PVA fibers increased the toughening and toughening effect on cement-based materials with the addition of fly ash, and the effect was more pronounced at high dosage. After the fly ash was mixed, The bridging stress of PVA fiber and the cohesive force of fiber-matrix interface in the crack are reduced. As the crack propagates, the PVA fiber changes from short-distance sliding to long-distance sliding. The fiber bridging crack efficiency increases and the toughening effect increases. After the fly ash, the matrix structure is more uniform, the distribution coefficient of PVA fiber is increased, and the toughening effect of PVA fiber on cement-based material is enhanced.