An empirical model for electrical resistivity of mortar considering the synergistic effects of carbon fillers, current intensity, and environmental factors

Abstract

Before using smart devices based on cementitious composites to monitor strain or stress in structures, it is essential to calibrate the initial values of these devices under different measurement conditions and environmental factors. Therefore, it is highly necessary to develop a predictive model for the electrical resistivity of the materials in an unloaded state, considering the synergistic effects of these factors. The primary objectives of this study are as follows: (i) to clarify the effects of carbon fillers, current intensity, temperature, and moisture on the initial electrical resistivity of unloaded mortar, and (ii) to enhance the predictive ability of the empirical model based on the Arrhenius equation by considering the synergistic effects of these factors. To achieve these objectives, around 280 electrical resistivity measurements were performed on mortar specimens with four distinct mixture compositions. The microstructure and material porosity were also examined. The experimental results demonstrated that the current intensity, temperature, and moisture have a significant impact on the electrical resistivity of unloaded mortar, and these effects vary depending on the specific mixture composition of the mortar. After discussing the applicability of existing models, an empirical model based on the Arrhenius equation was developed, which exhibited a strong correlation with the measurement data.

Keywords

• Self-sensing mortar
• Electrical resistivity
• Carbon fiber
• Carbon black
• Excitation current
• Temperature