Self-sensing mortar utilizing waste carbon black: sustainable material for smart structural health monitoring

This study examined waste carbon black (WCB) as a functional additive in self-sensing mortar. WCB is an industrial byproduct available in large quantities from manufacturing processes. It was added to mortar mixes at dosages ranging from 0% to 5% by weight of cement. The study assessed the influence of WCB on mechanical strength, electrical conductivity, and sustainability performance. Results show that WCB additions up to 2.5% meaningfully improve both mechanical and electrical properties. The strength gain is attributed to the micro-filler effect, where WCB particles fill micro-voids and improve the packing density of the cementitious matrix. The incorporation of WCB into mortars enhances their electrical conductivity, opening possibilities for smart concrete structures with self-monitoring capabilities. Furthermore, a calibration curve was developed to correlate the specific resistance and compressive strength with the curing age. The calibration curve could assist in real-time monitoring through embedded sensors, potentially improving structural health monitoring systems. This study demonstrated that WCB is a sustainable and useful additive. Life cycle assessment confirmed that incorporating 2.5% and 5% WCB reduced the global warming potential by 1.72% and 3.57%, respectively, relative to the control mix. By combining sustainability with smart functionality, this study contributes to the development of intelligent infrastructure with improved safety.