Concrete Bridge Deck Crack Sealant Evaluation and Implementation

A total of 12 sealant products were applied on the Smith Avenue High Bridge in St. Paul and evaluated over a three-year period. Details, such as surface preparation and application methods, were documented for each product and are conditions specific to each product. Sealant performance was evaluated through field permeability testing, visual observations, and petrographic examination. Visual observations provided evidence that approximately 67 percent of test sections were performing effectively after one winter but only 4 percent after two winters. After three winters, 58 percent of the test locations were visually characterized as ineffective and 42 percent as partially effective. Product performance significantly reduced over the third winter, primarily due to major loss of sealant and surface sand materials. Coring was performed after the second winter, and the cores were photographed and subjected to a petrographic evaluation. The observed depth of sealant penetration was highly variable and likely is dependent on the presence of debris within the crack, original crack width, and the deck temperatures during application. The predominant failure mode observed under magnification was detachment from the crack face and not within the sealant materials. Based on numerous factors, four epoxy and three methacrylate products were recommended for consideration on MnDOT's Approved Products List. Each product recommendation contains the surface preparation and application method conditions under which they were applied. It is also recommended that MnDOT look into increasing the frequency of its routine crack sealing maintenance program from the current five-year cycle.