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韧性指标是评价超高韧性水泥基复合材料(简称UHTCC)独特力学性能的重要指标。对比各国关于钢纤维混凝土弯曲韧性的测定与评价标准,该文以美国ASTMC1018标准、德国纤维混凝土标准和奥地利喷射混凝土标准为基础,分别采用等效抗压强度feq,n和开裂后的变形能Anp、韧性等级、评价纤维增韧作用的相对韧性指标RT1和评价UHTCC峰值后韧性的相对韧性指标RT2,从不同的角度详细定量地评价UHTCC的受压韧性性能。通过对棱柱体抗压强度在33MPa―52MPa之间的6组不同抗压强度的UHTCC进行单轴抗压试验表明,随着棱柱体抗压强度的增加,UHTCC开裂后所吸收的变形能和等效抗压强度增加;相对韧性指标计算结果表明添加体积分数为2%的PVA纤维使UHTCC的韧性性能达到相应基体韧性性能的2.6倍―3.8倍;使UHTCC峰值后的韧性性能达到峰值前的1.7倍―2.2倍,并证明纤维的作用主要体现在基体开裂后的韧性提高上;UHTCC的受压韧性等级主要在一级和二级之间。各组韧性指标均证明UHTCC具有较高的受压韧性性能和塑性变形能力,以及开裂后的高荷载承受能力。
Toughness index is an important index for evaluating the unique mechanical properties of ultra-high toughness cementitious composites (referred to as UHTCC). Based on the standards of American ASTMC1018, German Fiber Reinforced Concrete and Austrian Shotcrete, the equivalent compressive strength feq, n and the cracked deformation energy Anp were respectively compared with those of other countries on the flexural toughness of steel fiber reinforced concrete. , The toughness grade, the relative toughness index RT1 for evaluating the toughening effect of the fiber, and the relative toughness index RT2 for evaluating the toughness after the UHTCC peak. The compression toughness performance of the UHTCC was evaluated quantitatively from different angles. Uniaxial compression tests on six groups of UHTCC with compressive strength of between 33MPa and 52MPa show that with the increase of the compressive strength of the prism, the deformation energy absorbed by the UHTCC after cracking The results of relative toughness calculation show that the addition of PVA fiber with volume fraction of 2% makes the toughness of UHTCC reach 2.6 times -3.8 times that of the corresponding matrix; the toughness after UHTCC peak reaches 1.7 Times -2.2 times, and prove that the role of the fiber is mainly reflected in the toughness of the substrate after cracking; UHTCC compression toughness level is mainly between the first and second. Each group of toughness indicators have proved that UHTCC has high compression toughness and plastic deformation capacity, as well as high load capacity after cracking.