高温后PVA纤维增强水泥基复合材料力学性能试验研究

Study on Mechanical Properties of PVA-ECC Composites After Elevated Temperature

对经过100℃、200℃、400℃、600℃高温处理后的聚乙烯醇纤维增强水泥基复合材料(PVA-ECC)进行了单轴压缩试验、单轴拉伸试验、剪切试验和四点弯曲试验,对不同温度下的试验结果进行了对比分析,拟合了高温后PVA-ECC各项性能的退化曲线,并通过扫描电镜观察了微观结构。结果表明:PVA-ECC在常温下能够表现出良好的变形能力;当温度由常温升至100℃时,抗压强度大幅下降,继续升至200℃时则有一定提高;当温度超过200℃以后,抗压强度、抗拉强度和极限拉应变均降低,试件由延性破坏变为脆性破坏;常温下,PVA-ECC试件表面密实完整,经过400℃高温处理后,试件呈现出稀疏多孔结构,温度超过600℃时,试件表面呈片状、海绵状形态。

Uniaxial compression,uniaxial tensile,shearing and four-point bending tests were carried out on polyvinyl alcohol fiber reinforced cement-based composite materials(PVA-ECC)after high temperature treatment at 100℃,200℃,400℃and 600℃.The test results at different temperatures were compared and analyzed,the degradation curves of various properties of PVA-ECC after high temperature were deduced,and the microstructure was observed by scanning electron microscope.The results show that PVA-ECC has good deformation capacity at room temperature.When the temperature rises from room temperature to 100℃,the compressive strength decreases greatly,and then increases to a certain extent when it continues to rise to 200℃.When the temperature exceeds 200℃,the compressive strength,tensile strength and ultimate tensile strain of PVA-ECC are reduced,and the specimen changes from ductile failure to brittle failure.At room temperature,the surface of PVA-ECC is dense and complete.After being treated at 400℃,the specimen exhibits a sparse porous structure.When the temperature exceeds 600°C,the surface of the specimen becomes flake and sponge.