Use of prestressed rubber strips for cracking prevention of reinforced concrete bridge piers due to chloride attack

Conventional repair methods for chloride-induced corrosion often fail to provide long-term durability in bridge piers. Since natural compressive stress is insufficient to hinder chloride ingress, this study investigates prestressed rubber strips as a novel solution to introduce beneficial compression, enhance durability, and extend service life in chloride-exposed concrete structures. The investigation focused on short-span bridge piers (400 × 400 mm), designed according to standard reinforcement details for 5–6-meter spans. Plain Para rubber pads (hardness grade 50, dimensions 40 × 200 × 500 mm) were used to apply external compression. Chloride ingress was evaluated using two methods: (1) accelerated testing by immersion in a 14% chloride solution and (2) long-term field exposure in brackish water. Similar diffusion coefficients were found in both cases, confirming that chloride ingress was mainly controlled by the concrete’s permeability, which was consistent across specimens from the same batch. Notably, applying compressive force via pre-stretched rubber strips significantly reduced chloride diffusion, with the most effective reduction achieved at 100% elongation. Further assessment of degraded piers, simulating reinforcement corrosion from chloride attack, showed that post-tensioning with Para rubber strips restored and enhanced both flexural capacity and ductility. Improvements were most notable in specimens with greater reinforcement loss, demonstrating the technique’s potential to extend the service life of marine-exposed concrete structures.