Laboratory and field study on the performance of microcapsule-based self-healing concrete in tunnel engineering

Microcapsule-based self-healing concrete was used in a tunnel engineering project in the Qianhai area, Shenzhen and 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 microcapsules 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 10% microcapsules gradually increased over time. The microcapsules had both positive and negative effects on the microstructure of the self-healing concrete. The use of the microcapsules resulted in a significant increase in the long-term shrinkage but the amount of shrinkage is acceptable for practical applications. No significant difference of the strain evolution was observed between the experimental and control groups in the field test, indicating that the use of microcapsule-based self-healing concrete is feasible and promising to improve the durability of concrete structures, especially in coastal civil engineering. (C) 2019 Elsevier Ltd. All rights reserved.