ABSTRACT
Self-healing concrete based on microcapsules has been prepared in Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, Shenzhen University. In order to verify the performance of the self-healing concrete, it has been used in a tunnel engineering project in the Qianhai area, Shenzhen. The concrete performance was investigated using laboratory and field tests. The physical properties of the microcapsules and the microstructure of the self-healing concrete were experimentally investigated. The effects of the micro-capsules on the strength, permeability, and long-term shrinkage of the self-healing concrete were also investigated. The self-healing efficiency was evaluated using a compressive strength test and a rapid chloride migration (RCM) test. The results indicated that the self-healing functionality of the concrete containing microcapsules gradually increased over time. Microcapsules had dual effects on the mechanical properties of self-healing concrete. The incorporation of microcapsules increased the self-healing efficiency of the concrete in terms of mechanical strength after 7-day healing and decreased the compressive strength in comparison to the control group. On the other hand, significant improvement was observed in the impermeability of self-healing concrete. The use of the microcapsules resulted in an increase in the long-term shrinkage but the amount of shrinkage is acceptable for practical applications. It has been demonstrated that the concept of the microcapsule-based self-healing system is feasible and promising and microcapsules have great potential for use in self-healing concrete for sustainable infrastructure.
