Decoupling the effects of conductive fillers, water-binder ratio, and water reducer on the electrical and self-sensing properties of cementitious composites

Self-sensing cementitious composites (SSCC) have attracted increasing interest due to their combined structural and sensing functions; however, their electrical and self-sensing performance is governed by strongly synergistic effects of conductive filler content, water-to-binder ratio, and water reducer dosage, hindering rational optimization. To decouple these factors, this study systematically investigates their synergistic effects on the resistivity, fractional change in resistivity (FCR), stress sensitivity (SES), and strain sensitivity (SAS) of SSCC, as well as establishes a semi-empirical model based on conductive mechanisms revealed by AC impedance spectroscopy. The optimized SSCC exhibits a FCR of 13.04%, a SES of 1.09%/MPa, and a SAS of 130.01, representing an approximately 15-fold enhancement over unoptimized composites with the same filler content. The semi-empirical model achieves high predictive accuracy (R² = 0.962), showing excellent agreement with the experimental results. This study provides an applicable framework for designing and predicting the electrical performance of SSCC in engineering applications.