An experimental study on the influence of fly ash and crumb rubber on the mechanical property and permeability of Engineered Cementitious Composite (ECC)

Interest in using Engineering Cementitious Composites (ECC) for waterproof reinforcement has rapidly risen in recent years. Many studies revealed the excellent mechanical properties and waterproof ability of ECC, and analytical models have been proposed for predicting the permeability of ECC at different strain levels. However, the tailoring theory of ECC leads to the fact that the mechanical properties and waterproof ability can be further improved by incorporating different binders and aggregates and adjusting their proportions. Therefore, the applicability of current permeability models on the ECC with different mix proportions still needs to be researched. This paper focuses on adding fly ash and crumb rubber to enhance the waterproof ability of ECC. Mechanical properties and permeability experiments at different tensile strain were conducted for ECC with various mix proportions, and the effects of fly ash and crumb rubber on the improving the ductility and reducing permeability were revealed. In addition, the accuracy of the model for different mix proportions and different strain levels was studied. It is revealed that both fly ash and crumb rubber lead to a higher ductility, denser crack pattern and lower permeability, and ECC with fly ash has a better performance than ECC with crumb rubber at high strain level. The analytical model for permeability of ECC was proved to be accurate when few crumb rubber is added, while overestimate is observed for high crumb rubber content experiments. The findings of this research will contribute to the mix proportion design of ECC for waterproof reinforcement application.