Strategic Evaluation of Different Topical Protection Systems for Bridge Decks and the Associated Life-Cycle Cost Analysis

Bridge decks deteriorate faster and require more maintenance and repair than any other structural components on highway bridges. Topical protection systems act as barriers to protect bridge decks from corrosion damage by preventing water, oxygen, and chloride ions from reaching the reinforcement. This study evaluated topical protection systems commonly used on highway bridge decks in Colorado, including low-permeability concrete overlays and waterproof membranes with asphalt overlays. Five bridges were selected for inspection in the project. Concrete cores were taken from the selected bridge decks, and chloride concentration profiles were obtained at various depths. Chloride concentration is an important indicator for the corrosion damage of rebars in concrete deck. The inspection results showed that all five bridge decks are currently in good shape, which means the protection systems used on the selected bridges are effective. In order to predict future performance of the protection systems, a model was developed to predict the corrosion initiation time for rebars based on the current inspection results. The main feature of the prediction model is that the effect of deterioration of the concrete on its chloride permeability can be taken into account by using the current and future inspection results, and the deterioration could be due to environmental and/or traffic loadings. The prediction model for corrosion initiation time will be a useful tool for evaluating the effectiveness of topical protection systems. To better predict the future performance of bridge decks and the effectiveness of the topical protection systems, more inspection data are required for more reliable information on the deterioration rates of the bridges.