Thin polymer overlays (TPOs) enhance the safety of bridge decks by increasing skid resistance; but they also act as barriers to chloride ingress. TPOs are often applied to concrete bridge decks before they are opened to traffic and have a 10-to 15-year service life. It was hypothesized that delaying the application of the TPO and allowing some chlorides to penetrate the deck would not compromise the service life of the bridge deck and offset the application and repair costs. A program modeling chloride ingress was developed to predict the optimum time for TPO application to prevent chloride concentration from reaching threshold concentration and maximize the service life of the first TPO.
The program works in Microsoft Excel to model chloride distribution from a surface boundary condition using Fick’s second law and finite difference method. Although the method is not new, MnDOT’s implementation is tailored toward common bridge deck preservation activities and modeling needs. The appendices within the report walk through most usage examples in lieu of a manual.
NOTE: The Excel macro file is 120 MB in size and may be accessed from
https://edocs-public.dot.state.mn.us/edocs_public/DMResultSet/download?docId=15417346
