三维石墨烯-碳纳米管对超高性能混凝土机敏性能的影响

Effect of Three-dimensional Graphene-Carbon Nanotubes on the Smart Performance of Ultra-high Performance Concrete

本工作探索了掺加三维石墨烯-碳纳米管(Graphene-CNT,GC)的超高性能混凝土(Ultra-high performance concrete, UHPC)复合材料的机敏性能,基于四电极法分析了不同GC掺量、加载幅度、加载速度、温度和含水率对UHPC的电阻率变化规律的影响。研究结果表明:GC掺量对UHPC的28 d抗压强度影响不大;UHPC电阻率随着GC掺量的增加逐步降低,含有2.0%(质量分数,下同)GC的UHPC电阻率较R组下降了55.1%;UHPC试件电阻率随内部相对含水率的增加而降低,且二者存在线性关系;UHPC的电阻率随温度的升高而降低,电阻率的自然对数与绝对温度的倒数呈线性关系;UHPC电阻率变化率幅值随着加载幅度增大而增加,表现出良好的压敏特性,1.2%GC掺量下UHPC试件的压缩应力和应变灵敏系数分别达到0.2%/MPa和85.2。

Three-dimensional graphene-carbon nanotubes (Graphene-CNT, GC) were incorporated with ultra-high performance concrete (UHPC) in this work. The effects of GC content, loading amplitude, loading speed, temperature and water content on the resistivity variation pattern of UHPC were analyzed based on the four-electrode method. The results showed that the GC content has little effect on the 28 d compressive strength of UHPC. UHPC resistivity decrease gradually with the increase of GC content, and the resistivity of UHPC with 2.0wt%GC decreased by 55.1% compared with the control group. UHPC resistivity decreased with increasing internal relative water content, and there was a good linear relationship between relative water content and resistance. UHPC resistivity decreased with increasing temperature, and the natural logarithm of resistivity was linearly related to the inverse of the absolute temperature. The amplitude of resistivity change of UHPC increased with the increase of loading amplitude and showed excellent piezoelectric properties and electric conductivity. Moreover, the compressive stress and strain sensitivity coefficients of UHPC specimens with 1.2wt%GC reached 0.2%/MPa and 85.2, respectively.