Sustainable Self-Sensing Mortar with Hybrid Fillers for Early Damage Detection

Structural Health Monitoring (SHM) is important for guaranteeing the safety and longevity of civil infrastructure. Self-sensing cementitious composites offer a promising solution, yet they often face a trade-off between performance and cost. This study aims to develop a high-performance and cost-effective engineered cementitious composite (ECC) using a hybrid filler system of activated carbon powder (AC) and carbon fibre cord (CFC). The study investigated the synergistic effects of combining AC and CFC in varying hybrid ratios: (0.67 wt.%, 1vol.%), (1.33 wt.%, 0.67 vol.%), and (2 wt.%, 0.33 vol. %). The formulation with AC 0.67% by weight of cementitious composites and CFC 1% by total volume of mixture (AC0.67CFC1) had the best and most balanced performance. This optimal hybrid system showed significant improvements in uniaxial compressive and splitting tensile strength by 38% and 169%, respectively, compared to the control group. Most importantly, it demonstrated a reliable and significant self-sensing response under monotonic compressive and splitting tensile loads and exhibited exceptional stability during cyclic compressive loading. These results indicate that the strategic hybridization of low-cost AC with a small amount of CFC composites can produce a high-performance, strong, and economical composite, characterized by self-sensing. This represents a practical and sustainable pathway for the widespread on-site application of SHM techniques in civil infrastructure.