Introducing artificial flaws in Engineered cementitious composites (ECC) through nanocomposite coating of aggregates: A novel approach and mechanism

This study introduces a novel method for incorporating artificial flaws in Engineered Cementitious Composite (ECC) by applying carbon nanotube (CNT) polymer nanocomposite coatings, which has a porous microstructure, to aggregates. In comparison with the control ECC, the implementation of coated aggregates can improve the crack number and the strain capacity of ECC by 268 % and 83.7 %, respectively, while only incurring a 14.1 % decrease in compressive strength. Furthermore, increasing the sand-to-binder (s/b) ratio from 0.36 to 0.75 can improve the strain capacity of ECC by 213.1 %, with a reduction of compressive strength by 22.6 %. The underlying mechanisms were investigated both experimentally and theoretically, which revealed that the reduced spacing between artificial flaws significantly increases the stress concentration factor, thereby facilitating crack initiation and propagation. The simplicity, cost-effectiveness, and general applicability of this coating technique offer a valuable method for enhancing the performance of ECC, which could substantially advance its practical applications.