高性能PVA纤维增强水泥基复合材料单轴受拉特性

TENSILE PERFORMANCE OF HIGH PERFORMANCE PVA FIBER REINFORCED CEMENTITIOUS COMPOSITES UNDER UNIAXIAL TENSION

高韧性PVA纤维增强水泥基复合材料具有很高的能量吸收能力,但强度通常较低,采用我国地方材料资源和工业废料,可制备出高强度同时极限变形量满足实际工程要求的高性能PVA纤维增强水泥基复合材料(HPFRCC),以应用于高层抗震建筑结构的关键部位。通过单轴受拉强度和变形特性试验,研究PVA纤维体积率、粉煤灰掺量、硅灰掺量、水胶比及砂胶比对HPFRCC抗拉性能的影响,研究结果表明:随着PVA纤维体积掺量的增加,HPFRCC的抗拉强度与极限拉应变增大;大掺量粉煤灰替代水泥及增大水胶比可降低HPFRCC的抗拉强度,但明显改善其受拉应变硬化特性;HPFRCC中掺入适量硅灰及细砂可提高其抗拉强度,但极限拉应变降低,尤其当砂胶比较大时,HPFRCC的受拉应变硬化现象不明显;基于细观力学模型,分析了各因素对HPFRCC拉伸应变硬化特性影响的原因,研究结果可为今后HPFRCC的实际工程应用提供基础依据。

HPFRCC with high toughness has high energy absorption capability, but strength is often relatively low. By using the local material resource and industrial waste, HPFRCC were prepared, which has high strength and deformation meeting the practical engineering need. It can be applied to the key positions of tall earthquake-resistant structures. Based on experiments for strength and deformation under uniaxial tension, the influences of PVA fiber content by volume, fly ash and silica fume content, water to binder ratio and sand binder ratio on tension performance of HPFRCC were studied. Study results indicate that as PVA fiber content by volume increases, the tensile strength and ultimate tensile strain of HPFRCC increase. High volumes of fly ash replacement of cement and increasing water to binder ratio reduce tensile strength of HPFRCC, but significantly improve its tensile strain hardening characteristics. While incorporating the right amount of silica fume and fine sand, tensile strength of HPFRCC can increase, but tensile strain reduce. Especially when the sand binder ratio is high, tensile strain hardening phenomenon of HPFRCC is not obvious. Based on the micro-mechanical model, the causes of influence factors on tensile strain hardening properties of HPFRCC are also analysed. The study can serve as a foundation for the practical engineering application of HPFRCC.