Abstract

The purpose of this research was to identify the types of surface treatments available for use on concrete bridge decks and to determine which materials are most capable of providing long-term protection from contamination by chloride ions. The products addressed in this report primarily include urethanes, silicon-based sealers, and epoxies. An extensive literature review was conducted to document common overlay distresses, performance histories, and properties of specific surface treatment products currently available in the industry. In addition, three reports summarizing in-house experiments performed by the Utah Department of Transportation between 1995 and 2003 regarding various types of surface treatments were reviewed as part of this research. Finally, a nationwide questionnaire survey was conducted to investigate the state-of-the-practice with regard to surface treatment applications on bridge decks by state departments of transportation throughout the United States. Of the three types of materials addressed in this research, epoxy-based products have the greatest ability to protect concrete and remain uncracked with an acceptable level of skid resistance. Silicon-based products do not crack because they seep into the pores of the concrete, but they do not protect the concrete from the wearing effects of traffic or improve skid resistance. Published field studies indicate that urethane surface treatments do not resist the effects of traffic as well as epoxy-based materials, nor do they offer a substantial decrease in expense or health risk when compared to epoxy-based products. The results of the nationwide questionnaire clearly indicate that bridge deck surface treatments are valuable as both chloride barriers and skid-resistant wearing courses. No standard practice appears to exist with regard to timing of surface treatments, however. Some states arbitrarily apply surface treatments at 10 to 12 years after construction, other states wait until cracking has become fairly considerable before action is taken, and still other states apply surface treatments when the chloride content of the concrete reaches a certain level. Because concrete decks with significant cracking are not ideal substrates for polymer applications, surface treatments should be applied as preventive measures early in the service lives of bridge decks to effectively prevent chloride concentrations from reaching critical levels. This research suggests that epoxy-based surface treatments should be specified for concrete bridge decks when both a chloride barrier and improved skid resistance are desired. If a chloride barrier is all that is needed or desired, a silane surface treatment should be considered; silane treatments are less expensive and easier to apply than epoxy treatments. When a large amount of epoxy is to be mixed, automatic proportioning equipment that can precisely monitor and control the ratios of components should be employed.

Degree

College and Department

Ira A. Fulton College of Engineering and Technology; Civil and Environmental Engineering

Rights

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