Piezoresistivity of smart carbon nanotube/cementitious composite has been experimentally investigated, but the piezoresistive performance had been rarely studied when exposed to elevated temperatures. In this study, the physicochemical and mechanical properties, and piezoresistive behaviours of multi-walled carbon nanotube (MWCNT) reinforced smart cementitious composite were investigated under heat treatments of elevated temperatures of 300 °C and 600 °C. The microstructures, crystal deterioration and thermal gravity relationships were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and thermos-gravimetric (TG) analysis. The results show that the compressive strength and elastic modulus of MWCNT/cementitious composite after heat treatments gradually decreased, especially under the high temperature of 600 °C. There was a sudden growth of fractional changes of resistivity (FCR) after heat treatment. The higher temperature treatments led to more extensive sudden increase in the piezoresistivity. In the linear part of the relationship curves of FCR to the strain, the gauge factor even increased at the temperature of 300 °C. Moreover, the mechanism for the altered piezoresistivity was fundamentally explained and discussed by the MWCNT purification and destructions of MWCNT, cement matrix and agglomerations after heat treatments. Therefore, the related outcomes will promote the understanding and application of smart MWCNT/cementitious composite for structural health monitoring (SHM) under extreme environments.

智能碳纳米管/胶结性复合材料的压阻已经进行了实验研究，但是当暴露于高温下时，很少研究压阻性能。在这项研究中，研究了在300°C和600°C的高温下热处理的多壁碳纳米管（MWCNT）增强智能水泥基复合材料的理化和力学性能以及压阻特性。通过扫描电子显微镜（SEM），X射线衍射（XRD）和热重分析（TG）分析表征了微结构，晶体劣化和热引力关系。结果表明，热处理后MWCNT /水泥基复合材料的抗压强度和弹性模量逐渐降低，特别是在600°C的高温下。热处理后，电阻率（FCR）的分数变化突然增加。较高的温度处理导致压阻的更大范围的突然增加。在FCR与应变的关系曲线的线性部分中，在300°C的温度下，应变系数甚至增加。此外，从根本上解释和讨论了通过改变碳纳米管的纯度以及热处理后碳纳米管，水泥基体和团聚的破坏来解释改变压阻的机理。因此，相关结果将促进在极端环境下智能MWCNT /胶结复合材料在结构健康监测（SHM）中的理解和应用。较高的温度处理导致压阻的更大范围的突然增加。在FCR与应变的关系曲线的线性部分中，在300°C的温度下，应变系数甚至增加。此外，从根本上解释和讨论了通过改变碳纳米管的纯度以及热处理后碳纳米管，水泥基体和团聚的破坏来解释改变压阻的机理。因此，相关结果将促进在极端环境下智能MWCNT /胶结复合材料在结构健康监测（SHM）中的理解和应用。较高的温度处理导致压阻的更大范围的突然增加。在FCR与应变的关系曲线的线性部分中，在300°C的温度下，应变系数甚至增加。此外，从根本上解释和讨论了通过改变碳纳米管的纯度以及热处理后碳纳米管，水泥基体和团聚的破坏来解释改变压阻的机理。因此，相关结果将促进在极端环境下智能MWCNT /胶结复合材料在结构健康监测（SHM）中的理解和应用。MWCNT的提纯以及热处理后MWCNT，水泥基体和团聚的破坏，从根本上解释和讨论了改变压阻的机理。因此，相关结果将促进在极端环境下智能MWCNT /胶结复合材料在结构健康监测（SHM）中的理解和应用。MWCNT的提纯和热处理后MWCNT的破坏，水泥基体和团聚作用从根本上解释和讨论了压阻变化的机理。因此，相关结果将促进在极端环境下智能MWCNT /胶结性复合材料在结构健康监测（SHM）中的理解和应用。