Damage mechanisms of ultra-high-performance concrete under freeze-thaw cycling in salt solution considering the effect of rehydration

Accelerated freeze-thaw cycling tests in 5.0 wt% NaCI solutions were performed to better understand the durability of ultra-high-performance concrete (UHPC) with a 0.2 water-binder ratio under freeze-thaw cycles in a salt environment (as experienced by concrete used in harsh marine environments). The bound water and pore structure were evaluated before and after cycling. Unhydrated cement rehydrated during the freeze-thaw cycling and hydration products repaired small pores (<100 nm). The ice-formation expansion rates of 0-10 wt% NaCI solutions were determined. The damage mechanisms were discussed considering the supercooling effect and salt concentration. The conclusions of this study are valid for specific properties of UHPC under freeze-thaw cycling in salt solution. (C) 2018 Elsevier Ltd. All rights reserved.