Synergistic effects of carbon fibre and limestone powder on the mechanical performance and eco-efficiency of electrically conductive cementitious composites

Abstract This study evaluates the synergistic effects of carbon fibre and limestone powder on electrically conductive cementitious composites (ECCC) properties, considering fresh and hardened states, electrical conductivity, eco-efficiency, and microstructure. An experimental design comprising eight mixtures was adopted, varying the carbon fibre content (0.00, 0.50, and 1.00 wt.%) and replacing cement with limestone powder (0.00, 10.00, and 20.00 wt.%). The investigated properties included consistency, compressive and flexural tensile strengths, elastic modulus, water absorption, electrical resistivity, and microstructural analysis by scanning electron microscopy. A polynomial regression model was used to evaluate the significance of the main effects and their interactions. The combination of 0.5% carbon fibre and 10–20% limestone powder yielded the best results, with compressive strength gains of up to 46% and reductions in electrical resistivity exceeding 97%. The eco-efficiency indices (Bi and Bs) confirm that hybrid optimisation strategies significantly reduce cement demand while enhancing the overall performance of ECCC. This strategy represents a viable alternative to produce high-performance and eco-efficient ECCC suitable for applications in smart infrastructure.