Abstract Water and sand were used as the medium of multiwall carbon nanotube (MCNT) and prepared MCNT aqueous suspension and MCNT suspension-coated sand, respectively; afterwards, they were introduced into cement mortar (MNT/CM, MNTSM), respectively. Next, mechanical strengths and piezoresistive properties (DC resistivities (ρ v), AC impedances (Z r)) under cyclic loadings (σ c) of two types of MNT/CM and MNTSM nanocomposites were investigated to explore the intrinsic and self-sensing behaviors. Results reveal that MCNT can be evenly and well-coated on sand, which favors to achieve its intrinsic self-sensing property. Although the fraction changes in ρ v and Z r under the same σ c of MNTSM are both lower than those of MNT/CM, the stress sensitivity of MNTSM is only −1.16%/MPa (DC resistivity), −1.55%/MPa (AC impedance); its sensing linearity and stability (2.53, 2.45%; 2.73, 2.67%) are superior to those of MNT/CM (4.94, 2.57%; 3.78, 2.96%). Piezoresistivity using AC impedance technique is helpful to acquire balanced sensing sensitivity and stability while applied as intrinsic sensors in infrastructure.

中文翻译：

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碳纳米管包覆砂增强水泥砂浆的制备及压阻性能

摘要 以水和砂为多壁碳纳米管（MCNT）介质，分别制备了MCNT水悬浮液和MCNT悬浮包覆砂；之后，将它们分别引入水泥砂浆（MNT/CM、MNTSM）中。接下来，研究了两种类型的 MNT/CM 和 MNTSM 纳米复合材料在循环载荷 (σ c) 下的机械强度和压阻特性（直流电阻率 (ρ v)、交流阻抗 (Z r)），以探索其固有和自感行为. 结果表明，MCNT 可以均匀且良好地涂覆在沙子上，这有利于实现其固有的自感特性。尽管MNTSM在相同σ c 下ρ v 和Z r 的分数变化均低于MNT/CM，但MNTSM的应力敏感性仅为-1.16%/MPa（直流电阻率）、-1.55%/MPa（交流阻抗）；其传感线性度和稳定性（2.53, 2.45%; 2.73, 2.67%）优于MNT/CM（4.94, 2.57%; 3.78, 2.96%）。使用交流阻抗技术的压阻率有助于在基础设施中用作固有传感器时获得平衡的传感灵敏度和稳定性。