Investigation of self-healing property of UHPC with sus-tained loads under aggressive exposure environments

This paper describes a preliminary study into the healing performance of ultra-high performance con-crete (UHPC) with commercial crystalline admixtures (CA) when test samples were exposed to tap, geothermal, and salt water under sustained loads. The crack closure index was calculated using image processing techniques after one and two months of exposure. The results show that, as expectable, narrower cracks tended to gain better self-healing degrees. Exposure to salt water and geothermal water showed relatively low closure index values compared to exposure to tap water, with the worst state of geothermal water. This pattern was also validated by ultrasonic pulse velocity (UPV) test. Additionlly, the observation of the morphology of self-healing products also revealed an adverse effect on crystal growth and crystallization in the salt water and geothermal water, which could explain why the samples showed lower healing capacities in the corrosive water environment. This study will guide the design of UHPC and pave the way for the promotion of its application.