混杂PVA-ECC配合比优化设计及力学性能试验研究

为了降低工程用水泥基复合材料(ECC, Engineered Cementitious Composites)制造成本，使ECC能够在实际工程中大规模应用，将中国产PVA纤维和日本产PVA纤维以一定的比例混合，配制混杂PVA-ECC。基于ECC的材料设计理论，兼顾抗压强度和受拉能力，对掺有硅粉的混杂PVA-ECC中的纤维体积含量进行了优化设计。通过四点弯曲试验和轴心抗压试验，研究了混杂PVA-ECC在不同龄期下的弯曲性能和抗压性能。试验结果表明，混杂PVA-ECC试件均表现出明显的应变硬化和多缝开裂的特征，此外，其抗压强度后期增长明显。基于UM法，提出一种改进的反分析方法，可利用四点弯曲试验结果推导ECC的极限拉伸应变，并与试验结果进行了比较，结果表明,通过建议的反分析方法得到的预测值与试验值吻合较好。

Optimization of mix proportion and experimental analysis of mechanical properties of hybrid PVA-ECC

In order to reduce the production cost of Engineered Cementitious Composites (ECC), it is very necessary to substitute part of the expensive Japanese PVA fibers with the homemade PVA fibers for the ease of extensive application of the practical structures.Based on the ECC design theory, an optimal design for the fiber volume content of hybrid PVA-ECC is analyzed, taking both compressive strength and tensile strain capacity into account. The mechanical behavior of hybrid PVA-ECC is obtained through the four-point bending test and uniaxial compressive test. Experimental results indicate that the strain hardening and multiple cracking behavior of hybrid PVA-ECC are observed in the test, and the long-term compressive strength is distinctly increased. Furthermore, a modified inverse method based on the UM method is proposed, to use the measured data of four-point bending test to calculate the tensile strain capacity of ECC, and the proposed method is verified with the experimental results of hybrid PVA- ECC specimens.