The corrosion of reinforcing bars and prestressing steel is the most significant risk to the durability of concrete road bridges in New Zealand. The application of water-resistant surface treatments has been suggested as a means of delaying corrosion damage. This research, carried out between 2007 and 2010, reviewed international research findings and the use of preventive surface treatments by road-controlling authorities in Australia, the UK, and North America, to develop a guideline for selecting appropriate surface treatments for delaying chloride-induced corrosion damage on concrete road bridges in New Zealand.
The findings indicated that the effectiveness of surface treatments for reducing corrosion activity and extending service life depends not only on the chemical composition of the treatment, but also on the condition of the concrete substrate, the application process, and environmental exposure conditions.
A process was developed to identify the potential benefits of such surface treatments for individual bridges and for bridge populations.
Recommendations were made to help bridge owners and asset managers implement this process, including means of investigating concrete condition to complement economic evaluations, and considerations of monitoring and maintenance requirements for at-risk bridge elements before and after treatment.