Effects of Bending Load Level and Cementitious Capillary Crystalline Waterproofing Content on Chloride Transportation in Jointed Concrete

The composition and interface quality of jointed concrete can significantly influence chloride ion penetration, especially in coastal environments. This study investigates the transport behavior of chloride ions in concrete flexural members with varying joint configurations—no joint, smooth wet joint, and roughened wet joint—under different bending loads. After 28 days of curing, specimens were subjected to bending loads and immersed in an 8% NaCl solution for 300 days. Chloride ion concentrations were then measured at different depths and locations. Results revealed that joints, particularly smooth wet joints, significantly accelerate chloride ion transmission, and that chloride accumulation at the joint is consistently higher than in adjacent areas or jointless concrete. The apparent diffusion coefficient of chloride ions was notably higher at joint interfaces and increased with bending load level due to microcrack formation. Notably, the incorporation of Cementitious Capillary Crystalline Waterproofing (CCCW) in the concrete mix improved resistance to chloride ion penetration. A dosage of 1% CCCW proved most effective, reducing the diffusion coefficient at the joint by approximately 10%—demonstrating an optimal balance between performance and material efficiency. These findings provide practical guidance for improving the durability of jointed concrete structures in chloride-rich environments.