Self-Sensing concrete: A data-driven approach to comprehensive analysis and review

Structural health monitoring of civil infrastructure is vital in ensuring a safe and functional built environment. Self-sensing cementitious materials have emerged as a promising alternative in the field of concrete monitoring due to their pronounced sensing potential. Research into this field has been ongoing for decades, with new sensor designs being constantly proposed. It is therefore fundamental to review recent advancements to stay up to date with the current state-of-the-art. This review examines the sensing performance of self-sensing cementitious materials and presents a data-driven analysis based on 121 peer-reviewed sources. From the analysis, it was found that the gauge factor (GF) of these materials varies according to the number, type and concentration of conductive filler, type of cementitious matrix, mechanical testing method, and the type and number of electrodes. Most reported gauge factors were below 1000, with single-filler composites producing higher values under compression and multi-filler composites yielding higher values under tension and flexure. Nickel powder was found to result in the highest GF as a single filler, while the combination of carbon black and carbon fibre displayed the highest GF for multiple fillers. Combining fillers with different dimensional properties (e.g., 0D with 1D) can significantly enhance sensing performance by creating a more stable conductive network. In terms of concrete type, paste and mortar result in higher GFs compared to concrete and ultra-high-performance concrete. Regarding probe configurations, the two-probe method results in higher data variability compared to the four-probe method, with GFs exceeding 3000 and therefore, its reliability should be reconsidered. Combining data from different electrode configurations can also misrepresent results, highlighting the need to consider probe design when interpreting the sensing response. Overall, the findings of this paper underscore the need for standardised protocols to enable meaningful comparisons and reproducible results, thereby advancing our understanding of self-sensing cementitious materials.