Development of a novel ultra-high performance concrete (UHPC) suitable for underwater operation: Design and performance evaluation

This study has developed a new type of ultra-high performance concrete (UHPC) with excellent performance that can be used for underwater operations. Firstly, the sulfur aluminate cement(C S A)-gypsum(CS)-silicate cement(OPC) ternary system is used as the cementitious material, and the optimal mixture ratio of underwater non-dispersive ultra-high performance concrete (UN-UHPC) is designed by the D-optimal design method. Then, the macroscopic properties, hydration process, and microscopic structure of the developed UHPC are evaluated. The experimental results show that UN-UHPC has excellent performance and good anti-dispersion properties, with a cement loss rate of 4.8% and a total porosity of 3.39%. Besides, due to the incremental effect of water, UNUHPC has better mechanical properties and lower porosity than the one formed on land. In general, the developed UN-UHPC in this study further demonstrates the excellence and feasibility of D-optimal design in advanced building materials area and provides technical support for rapid underwater repair projects and the development of ocean resources.