Investigating the self-healing performance of cracked undersea constructions

The undersea construction has undergone long-term exposure to erosive high-pressure seawater. Hence, it has become urgent to meet long-term requirements for seepage resistance and corrosion resistance. The objective of this study was to delve into the feasibility of remedying capillary cracks narrower than 0.3 mm in concrete constructions by using self-healing properties of concrete within a marine environment. Through the test of pressurized water seepage, microexaminations, and numerical simulations of low water-to-binder ratio concrete subjected to simulated marine conditions, this study investigated the impacts of initial crack width, hydrostatic pressure, and curing age on water permeability, crack width, splitting tensile strength, and free chloride content in cracked concrete. The findings revealed that the concrete exhibiting capillary cracks with a width of under 0.3 mm indicated excellent self-healing performance. Notably, the results indicated the decrease in the water permeability, the gradual decline in surface crack width, and a slight recovery of the splitting tensile strength. However, the chloride ion transport was less evident compared to seepage as fracture closure decreased. The healing indexes of cracked concrete were enhanced with the decrease in the initial crack width, the shortening of curing period, and the decline in hydrostatic pressure. Moreover, the results demonstrated that the seepage velocity negatively impacted concrete healing, while continuous hydration during the early stages of concrete formation positively affected the healing process. These results provided valuable insights for devising maintenance strategies for concrete structures exposed to seawater environments.