Traditionally, conductive fillers are mixed directly with cement matrix before binding with aggregates to develop piezoresistive cement-based sensors. This results in the most vulnerable region, interfacial transition zone (ITZ), from which microcracks are initiated, merely located at the periphery of the conductive network and thus limits the sensitivity of the smart sensor. This study proposes a strategy to construct a three-dimensional (3D) conductive network in the mortar with ITZ directly embedded in it, thus greatly increasing both the conductivity and piezoresistivity without significantly sacrificing mechanical property. Highly conductive graphene-coated fine aggregates (termed conductive G@FAg particles) are prepared by adsorption of graphene oxide (GO) onto the fine aggregates (FAg) surface, followed by simple annealing and microwave treatment. The combined usage of conductive G@FAg particles and 0.1 wt% 6 mm-CF results in an outstanding electrical conductivity (resistivity of 580 Ω cm) and an excellent fractional change in resistivity (FCR of 30%) under cyclic compressive loading, with a negligible compressive strength loss of 3.1%. Remarkably, the addition of conductive G@FAg particles together with 0.5 wt% 10 mm-CF leads to an excellent conductivity (resistivity of 165 Ω cm) and self-sensing ability (FCR of ∼90%), which outperforms the previously reported mortar directly incorporated with the same concentration of CF and graphene. The much-improved conductivity and FCR value with such a low weight percentage of conductive carbon materials are attributed to the unique 3D network of conductive channels.

传统上，导电填料在与骨料结合之前直接与水泥基体混合，以开发基于水泥的压阻传感器。这导致最脆弱的区域，界面过渡区（ITZ），从那里引发微裂纹，仅位于导电网络的外围，从而限制了智能传感器的灵敏度。本研究提出了一种在砂浆中构建三维 (3D) 导电网络的策略，ITZ 直接嵌入其中，从而在不显着牺牲机械性能的情况下大大提高导电率和压阻率。通过吸附氧化石墨烯制备高导电石墨烯涂层细聚集体（称为导电 G@FAg 颗粒）(GO) 到细聚集体 (FAg) 表面，然后进行简单的退火和微波处理。导电 G@FAg 颗粒和 0.1 wt% 6 mm-CF 的组合使用导致在循环压缩载荷下具有出色的电导率（电阻率为 580 Ω cm）和电阻率的出色分数变化（FCR 为 30%），具有微不足道抗压强度损失 3.1%。值得注意的是，将导电 G@FAg 颗粒与 0.5 wt% 10 mm-CF 一起添加可产生出色的导电性（电阻率为 165 Ω cm）和自感应能力（FCR 约为 90%），优于先前报道的砂浆直接掺入相同浓度的CF和石墨烯。如此低重量百分比的导电碳材料的电导率和 FCR 值大大提高，这归功于独特的 3D 导电通道网络。