Abstract Manager

The Hawkshaw Bridge, a critical transportation asset in New Brunswick, Canada, faced increasing challenges with concrete deterioration in its substructure due to chloride ingress, threatening its long-term serviceability and structural integrity. Historically, the bridge, like many aging concrete structures, exhibited low to moderate chloride concentrations within its piers, necessitating a robust rehabilitation strategy to prevent further degradation and ensure continued safe operation. The primary objective of this project was to implement a sustainable rehabilitation solution for the bridge piers that would achieve a 30-year service life extension, bolster structural robustness, and minimize operational disruption.

The chosen methodology centered on a structural overbuild combined with an innovative corrosion mitigation system. This approach involved adding new structural elements atop and in conjunction with the existing piers, strategically enhancing load-carrying capacity and overall functionality without requiring full bridge replacement. This not only significantly reduced costs and construction time but also minimized traffic interruptions throughout the rehabilitation period. Integral to the overbuild was the incorporation of galvanic anodes as a cathodic protection system. This system was specifically designed to protect both the existing reinforcement steel and newly embedded steel within the overbuild from future corrosion, particularly in areas susceptible to chloride attack.

Through meticulous design and ongoing field data analysis, including anode consumption rates and performance monitoring, the cathodic protection system has been demonstrated to deliver a sustained, minimal current release, effectively extending the structure's service life as intended. The conclusions drawn from the Hawkshaw Bridge project highlight the efficacy of combining structural overbuild with galvanic anode technology as a viable and sustainable solution for aging concrete infrastructure. This case study demonstrates that such an integrated approach can extend the service life of existing structures by three decades, enhance structural capacity, and achieve these benefits with minimal traffic disruption. Furthermore, by preserving existing infrastructure rather than opting for full replacement, this rehabilitation strategy significantly contributes to reducing the carbon footprint associated with infrastructure development, offering a powerful model for environmentally responsible asset management.