Damage evolution of UHPC under coupled high stress, temperature, and osmotic pressure: New multi-field experiment and non-destructive techniques

Abstract

Underground structures in deep regions of ocean underground engineering are exposed to high stress, temperature, and osmotic pressure, which accelerate their damage and degradation. This work investigates the performance of ultra-high-performance concrete (UHPC) under these coupled conditions using a specially designed load-temperature-osmotic pressure coupling instrument. The damage evolution of UHPC was evaluated using ultrasonic pulse velocity (UPV), bulk density, and scanning electron microscopy (SEM). The results show that increasing the stress ratio causes greater damage to the UHPC while the damage and cracks in the UHPC under high temperatures and osmotic pressure are instead repaired. In addition, the number, width, and length of microcracks in UHPC increase with the increasing water-binder ratio. Reducing the water-cement ratio to 0.16 and incorporating 2 % steel fibers can result in the best performance in terms of damage resistance. These findings provide valuable insights into the application of UHPC in challenging underground structures in deep regions of ocean underground engineering.