纤维增强水泥基复合材料弯曲性能与纤维作用机理研究

STUDY ON BENDING PERFORMANCE AND MECHANISM OFFIBER REINFORCED CEMENTITIOUS COMPOSITES

通过四点弯曲试验,研究了5组不同PVA纤维掺量的纤维增强水泥基复合材料试件的弯曲性能。试验结果表明,纤维掺量对试件的弯曲性能有着显著影响,掺入适量纤维可以明显改善试件的脆性破坏特征,裂缝呈现出细而密的特点。当纤维体积掺量V f不超过2.0%时,初裂弯曲强度、峰值弯曲强度、等效弯曲强度值和韧性指标均随纤维掺量的增加而增大;而V f为2.5%的试件流动性能较差,部分纤维结团,弯曲强度较V f=2.0%组试件有所下降。结合荷载-挠度曲线,采用电镜扫描定性分析了复合材料中纤维的作用机理,对影响纤维桥联作用发挥的因素进行了研究。

To study the bending properties of fiber reinforced cementitious composite,five groups of specimens with different PVA fiber content were studied by four-point bending test.The experimental results show that the fiber content has a significant effect on the bending properties of specimens.Appropriate amount of fiber can significantly improve the brittleness of specimens,and crack is small and dense.When the fiber volume V f≤2.0%,the initial cracking bending strength,peak bending strength,equivalent bending strength and toughness index increase with the increase of fiber content.For specimens with V f=2.5%,the flowability is poor and some fiber agglomerates.As a result,the bending strength of specimens with V f=2.5%is lower than specimens with V f=2.0%.Combined with the load-deflection curve,the mechanism of fiber in the composite was qualitatively analyzed by scanning electron microscope,and the factors affecting the fiber bridging effect were studied.