Effect of water curing initiation time on abrasion resistance and chloride penetration resistance of hydraulic concrete

After recovery of the underwater pile foundation casing, the pile is exposed to water, and the bare pile faces damage from flow abrasion, chloride ion erosion, and other factors. This study investigates the critical yet underexplored effects of water curing initiation time (after initial standard curing) on the abrasion resistance and chloride ion penetrability of concrete. Hydraulic concrete’s abrasion resistance and chloride ion penetration resistance were assessed via a series of standardized durability trials; further, numerical simulation was used to elucidate the effect of water bath curing initiation on chloride ion diffusion in concrete. The results show that initiating water bath curing negatively impacted concrete’s abrasion performance—the abrasion resistance strength decreased from 1.72 h/(kg·m 2 ) (28 d standard curing) to 0.84 h/(kg·m 2 ) (water bath curing initiated at 3 d), corresponding to a reduction of 51.16%. Conversely, this practice improved chloride ion penetration resistance: the chloride diffusion coefficient decreased from 0.92 × 10⁻ 11 m 2 /s (water bath initiated at 17 d) to 0.26 × 10⁻ 11 m 2 /s (initiated at 3 d), representing a 71.73% reduction. Delayed water-bath curing initiation increased both abrasion resistance strength and chloride diffusion coefficient. Earlier initiation of water-bath curing extended the predicted service life of the concrete structure under diffusion-controlled conditions. These findings provide a basis for the timely removal of casing for unprotected underwater pile concrete and the evaluation of its service life.