An Evaluation Of Concrete Bridge Deck Overlays And Hma Bridge Deck Overlays With Waterproof Membranes PDF Download

The objective of this research was to assess the condition of four decommissioned bridge decks treated with waterproofing membranes and asphalt overlays following the completion of their service lives. Large samples were cut from each of the bridge decks immediately prior to demolition and taken to the Brigham Young University Highway Materials Laboratory, where extensive sampling and testing was performed. Methods used to evaluate the condition of the bridge deck samples included visual inspection, hammer sounding, Schmidt rebound hammer testing, resistivity testing, half-cell potential testing, linear polarization testing, cover depth measurement, and chloride concentration measurement. The samples were removed from four concrete bridge decks along the Interstate 15 corridor in Provo, Utah. One bridge deck was constructed in 1937, two were constructed in 1964, and one was constructed in 1984. Each of the bridge decks was constructed using conventional cast-in-place methods. With the exception of the 1984 bridge deck, which had epoxy-coated rebar, all of the bridge decks were reinforced with black bar. A waterproofing membrane was installed on each of the bridge decks in 1984, meaning each waterproofing membrane had been in service for 26 or 27 years at the time of sampling. With the exception of one of the bridges, which was in good condition after 26 years of service, each of the bridge decks sampled had successfully served for at least 46 years. Aside from asphalt maintenance, no rehabilitation was needed on any of the bridge decks following installation of the waterproofing membranes. Without the application of the waterproofing membranes, the chloride concentrations in the bridge decks likely would have been much higher. Additional exposure to chloride ions from deicing salts would have quickly increased the chloride concentration in the concrete above critical levels, which would have led to significant corrosion and bridge deck deterioration, prematurely. While the application of membranes as a bridge deck maintenance procedure has mostly been replaced by the use of epoxy-based polymer overlays, many bridge decks protected with membrane systems are still in service today. The research findings suggest that application of waterproofing membranes and asphalt overlays in a timely manner, before the accumulation of excessive amounts of chlorides within a deck, can be an effective approach for concrete bridge deck preservation.