PVA纤维水泥基复合材料力学与孔结构相关性研究

Research on the Correlation between Mechanics and Pore Structure of PVA Fiber Cement-based Composites

为研究PVA纤维对水泥基复合材料抗压性能的影响规律,制备了PVA纤维体积掺量分别为0%、0.5%、1%、1.5%、2%的5组水泥基复合材料试件,通过单轴压缩试验获得不同PVA纤维体积掺量下水泥基试件的抗压强度、峰值应变和弹性模量,分析PVA纤维体积掺量对试件力学参数的影响;再通过压汞试验获得试件的孔结构参数,分析其抗压强度与孔结构参数之间的相关性。结果表明:当PVA纤维体积掺量为0%~1%时,其对水泥基复合材料的抗压强度、峰值应变起正向作用;当PVA纤维体积掺量为1%时,水泥基复合材料的抗压强度和峰值应变达到最大值;当PVA纤维体积掺量为1%~2%时,其对水泥基复合材料的抗压强度、峰值应变起负向作用;水泥基复合材料的抗压强度和最可几孔径、临界孔径具有较高的负相关性,其抗压强度和孔隙率、孔容具有一定相关性,因此可以通过抗压强度对水泥基复合材料的孔结构尤其是孔径分布进行预测,水泥基复合材料的抗压强度越大,孔径分布越优。

To investigate the influence of PVA fibers on the compressive properties of cement-based composite materials,five sets of cement-based composite material specimens were prepared with PVA fiber volume contents of 0%,0.5%,1%,1.5%,and 2%,respectively.It obtains the compressive strength,peak strain,and elastic modulus of cement-based specimens with different PVA fiber contents through uniaxial compression tests,and analyze the influence of PVA fiber volume fraction on the mechanical parameters of the specimens;it obtains the pore structure parameters of the specimen through mercury intrusion testing and analyze the correlation between compressive strength and pore structure parameters.The results indicate that when the volume fraction of PVA fibers is between 0%and 1%,it has a positive effect on the compressive strength and peak strain of cement-based composite materials;when the volume fraction of PVA fibers is 1%,the compressive strength and peak strain of cement-based composite materials reach their maximum values;when the volume fraction of PVA fibers is 1%to 2%,it hurts the compressive strength and peak strain of cement-based composite materials;the compressive strength of cement-based composite materials has a high negative correlation with the most probable pore size and critical pore size.Its compressive strength has a certain correlation with porosity and pore volume.Therefore,the pore structure,especially the pore size distribution,of cement-based composite materials can be predicted through compressive strength.The greater the compressive strength of cement-based composite materials,the better the pore size distribution.