It has been known that the carbon nanotube (CNT)/cement composites can be used to reflect the external loading information and detect premature damage; however, the agreement on whether the piezoresistivity as a function of external loading is positive or negative has yet to be achieved, and the innate electrically conductive mechanism remains unclear. In this study, to minimize the application cost, small-size CNT/cement composites were embedded into the surface of the concrete as sensing elements, and the piezoresistivity of the CNT/cement composites under external loading along with/without salt attacks was tested. The results indicate that the piezoresistivity significantly depends on the percolation backbone density and the critical exponent of the CNT networks near the percolation threshold. Without salt environments, an “M” shape was observed in the curve of the fractional electrical resistivity (FCR) as a function of cyclic loading applied on the concrete samples. However, when the concrete samples were exposed to a salt environment, the “M” shape in the FCR curve disappeared. In addition, based on the percolation theory, the electrical resistivity changes as a function of strain fits well with an exponential function. The microstructure analysis demonstrates that the pore structure of the CNT/cement composites can be divided into spherical pores and cracks with layered structures. This study not only provides a new insight into the electrical conduction mechanism in CNT/cement composites systems but also sheds light on how to accurately monitor and analyze concrete structures with external loads, especially along with salt environment.

众所周知，碳纳米管（CNT）/水泥复合材料可用于反映外部载荷信息并检测过早损坏；然而，关于压阻率作为外部负载的函数是正还是负尚未达成一致，并且固有的导电机制仍不清楚。在本研究中，为了最大限度地降低应用成本，将小尺寸碳纳米管/水泥复合材料作为传感元件嵌入混凝土表面，并测试了碳纳米管/水泥复合材料在外部载荷以及/没有盐侵蚀下的压阻率。结果表明，压阻率显着取决于渗流骨架密度和渗流阈值附近 CNT 网络的临界指数。在没有盐环境的情况下，在作为施加在混凝土样品上的循环荷载的函数的分数电阻率（FCR）曲线中观察到“M”形状。然而，当混凝土样品暴露在盐环境中时，FCR曲线中的“M”形消失。此外，根据渗流理论，电阻率随应变的变化与指数函数非常吻合。微观结构分析表明， CNT/水泥复合材料的孔结构可分为球形孔和层状结构的裂纹。这项研究不仅为碳纳米管/水泥复合材料系统的导电机制提供了新的见解，而且还揭示了如何准确监测和分析具有外部载荷的混凝土结构，特别是在盐环境下。