Durability and self-healing of engineered cementitious composites exposed to simulated sewage environments

Corrosion factors including microbiologically induced corrosion accelerate cracking and deteriorations in a sewer concrete pipe especially in regions close to the pipe crown and that near the waterline. Engineered cementitious composites (ECC) is a novel class of ductile cement-based composites and possesses autogenously tight cracks and robust self-healing conducive to sewage environments resistance. This paper presents an experimental study on the durability of ECC exposed to sewage environments simulated by treatments including sulfuric acid exposure and physical erosion. The physical and mechanical properties of ECC were examined in relation to those of fiber-free mortar specimens as control. The objective of this research is to establish fundamental knowledge on the behavior of ECC under aggressive sewage environments. Results showed that the permeable voids increased, and the strength decreased for both ECC and mortar. However, the residual compressive and tensile strength of ECC were 30-65% and 300-370% higher than those of the mortar group after 12 corrosion cycles, respectively. After corrosion cycles, the length change ratio of ECC was about 20% of that of the control, which indicates that ECC has better dimensional stability under the corrosive conditions. Further, self-healing of microcrack damage was observed in ECC under all exposure conditions in this study. It is concluded that ductile ECC has significant advantages in mechanical and durability performance over conventional brittle mortar/concrete under the simulated environments unique in sewage lines. This research generates new data that establish ECC as a durable material for sewer pipeline construction and rehabilitation.

Automated summary

This study experimentally investigated the durability of engineered cementitious composites (ECC) in sewage environments. The results showed that ECC had better strength and dimensional stability compared to conventional mortar, making it a durable material for sewer pipeline construction.