Nanomaterial additives have been broadly used in cement and concrete-based sensors to measure the stress and strain in the structure. Most of the studies focused on measuring the resistivity of sensors with Direct Current (DC) or relatively low-frequency. In this work, the impedance responses of enhanced Carbon Nano-Fiber Aggregates (CNFAs) at different frequencies are rigorously studied and utilized as a tool for real-time structural health monitoring (SHM). The CNFA impedance measurements at different measurement frequencies provide an extra dimension (frequency dimension) to allow the characterization of different phenomena and multimodal measurements simultaneously. First, a comprehensive physical model is established to understand the frequency responses of the CNFA impedance. Second, COMSOL Multiphysics is used to simulate the frequency responses of the CNFA impedance, which provides more insights into the electric field and current density distribution. The impedance of CNFAs decreased with the increased dosage of carbon nanofibers (CNFs). Third, experimental studies are reported in detail. The electrical impedance variation (EZV) of the CNFA in parallel orientation is 151% higher than that of perpendicular orientation at the frequency of 2612 Hz and uniaxial compression stress of 4.65 MPa. The strain-EZV curve obtained from the response spectrum is linear for frequencies ranging from 98 Hz to 463.9 kHz. The strain-EZV curve for 5625 Hz has a linear fit with the gauge factor of 147.78. At 1000 Hz, the CNFA exhibited a repeatable behavior up to 9.35 MPa and detection limit up to the stress of 18.62 MPa.

纳米材料添加剂已广泛用于水泥和混凝土传感器，以测量结构中的应力和应变。大多数研究集中在用直流电 (DC) 或相对低频测量传感器的电阻率。在这项工作中，我们严格研究了增强型碳纳米纤维聚集体 (CNFA) 在不同频率下的阻抗响应，并将其用作实时结构健康监测 (SHM) 的工具。不同测量频率下的 CNFA 阻抗测量提供了一个额外的维度（频率维度），以允许同时表征不同的现象和多模态测量。首先，建立一个全面的物理模型来理解 CNFA 阻抗的频率响应。第二，COMSOL Multiphysics 用于模拟 CNFA 阻抗的频率响应，从而更深入地了解电场和电流密度分布。CNFAs 的阻抗随着碳纳米纤维 (CNFs) 用量的增加而降低。第三，详细报道了实验研究。在2612 Hz的频率和4.65 MPa的单轴压缩应力下，平行取向的CNFA的电阻抗变化（EZV）比垂直取向的电阻抗变化（EZV）高151％。从响应谱获得的应变-EZV 曲线在 98 Hz 到 463.9 kHz 的频率范围内是线性的。5625 Hz 的应变-EZV 曲线与应变系数 147.78 线性拟合。在 1000 Hz 时，CNFA 表现出高达 9.35 MPa 的可重复行为和高达 18.62 MPa 的应力检测限。