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选用总体积掺量不超过1%的钢纤维(SF)、塑钢纤维(MPF)和聚丙烯单丝纤维(PF),进行混杂纤维混凝土带切口梁三点弯曲试验,通过荷载-挠度曲线分析了纤维混杂方式和掺量对混凝土弯曲韧性的影响,对裂缝口张开位移-挠度曲线进行线性拟合,初步探究了基于荷载-裂缝口张开位移曲线的弯曲韧性评价方法。研究结果表明:三元混杂纤维增强混凝土具有较素混凝土、单掺及二元混杂纤维混凝土更优的弯曲韧性,基于弯曲韧性的最优混杂组合为0.7%SF、0.19%MPF、0.11%PF;跨中挠度δ与裂缝口张开位移呈较好的双折线关系,由基于荷载-挠度曲线的弯曲韧性评价方法得出的结论,与由基于荷载-裂缝口张开位移曲线的弯曲韧性评价方法得出的结论一致,通过荷载-裂缝口张开位移曲线对混杂纤维混凝土的弯曲韧性进行评价是可行的。
Three-point bending test of cut-beam with hybrid fiber concrete was carried out using steel fiber (SF), plastic fiber (MPF) and polypropylene monofilament fiber (PF) with the total volume not more than 1%. The load-deflection curve Fiber mixed mode and content on the flexural toughness of concrete, and the open displacement-deflection curve of the crack mouth were linearly fitted. The flexural toughness evaluation method based on the open-displacement curve of load-crack mouth was preliminarily studied. The results show that the ternary hybrid fiber reinforced concrete has better flexural toughness than plain concrete, single - mixed and binary hybrid fiber reinforced concrete. The optimal hybrid combinations based on flexural toughness are 0.7% SF, 0.19% MPF and 0.11% PF. The results show that the mid-span deflection δ and the open displacement of the crack mouth have a good birefringence relationship, and the conclusion based on the evaluation method of the bending toughness based on the load-deflection curve shows that the flexural toughness based on the load- The conclusions drawn are consistent. It is feasible to evaluate the flexural toughness of hybrid fiber reinforced concrete through the load-crack opening displacement curve.