Improved ECC tensile behavior and chloride resistance: Synergistic EPP-talc regulation effect

Engineered Cementitious Composites (ECC) exhibit high tensile ductility and multiple cracking. This study presents a synergistic modification approach utilizing expanded perlite powder (EPP) and talc to enhance the mechanical performance and chloride resistance of ECC. The findings indicate that EPP significantly improves tensile properties by serving as artificial defects that facilitate strain hardening. However, the introduction of EPP also results in the formation of very harmful pores, thereby increasing chloride permeability. To address these drawbacks, the incorporation of talc compensates for the aforementioned defects through a dual mechanism: (1) its laminar structure and lubricity reduce friction at the fiber-matrix interface, thereby mitigating fiber fracture; (2) its hydrophobic nature and reduced porosity inhibit chloride ion migration, effectively enhancing the chloride permeability of ECC, as evidenced by the decrease in D RCM from 2.6 × 10 -12 m 2 /s to 1.46 × 10 -12 m 2 /s. Through the synergistic interaction of EPP and talc, the mechanical properties of ECC are improved, as demonstrated by a 130.3% increase in ultimate tensile strain, while the compressive strength experiences only a marginal decrease of 12.8%. The study shows that the synergistic effect of EPP and talc can effectively balance the needs of ECC for high ductility, high strength, and reduction in chloride migration coefficient.