Effect of Hybrid Carbon-Based Fillers on Electrical and Mechanical Performance of Strain-Hardening Cementitious Composites (SHCCs)

Electrically conductive cement-based composites exhibit significant potential for a range of multifunctional applications. Nonetheless, the electrical and mechanical performance of ductile cement-based composites incorporating compound conductive additives has not been sufficiently explored. This study examines the effects of two distinct carbon-based fillers, namely carbon black and chopped carbon fibers, on strain-hardening cementitious composites (SHCC), and elucidates the synergistic mechanism of hybrid conductive fibers and fillers within SHCC. The findings indicate that a sufficiently high electrical conductivity can be achieved by incorporating 5 wt.% carbon black and 0.2–0.4 vol.% carbon fibers. The introduction of hybrid carbon-based fillers reduces the resistivity of SHCC by three orders of magnitude to less than 150 Ω∙cm, surpassing the performance of composites with a single carbon-based filler. Furthermore, the incorporation of hybrid carbon-based fillers and fibers enhances the compressive and flexural strength of cementitious composites. Compared to the referenced PE-SHCC, the tensile strength and strain of SHCC with 5 wt.% carbon black and 0.4 vol.% carbon fibers increased by 37.3% and 82.6%, respectively. A hybrid efficiency index (HEI) is proposed to assess both electrical conductivity and mechanical properties of SHCC incorporating with carbon-based fillers. The study’s findings offer an effective approach for utilizing hybrid carbon-based conductive fillers in the multifunctional applications of SHCC.