Evaluation of Thin Bonded Overlays as a Protective System for Highway Bridge Decks.

摘要

Chemical attack from chlorides, exposure to severe environmental conditions, and wearing from direct traffic loading causes highway bridge decks to deteriorate the fastest among all the structural components of a highway bridge. In an effort to better protect the bridge deck and reduce maintenance costs, State Departments of Transportation (D.O.T.) apply protective topical overlays to the bridge decks. The use of Thin-Bonded Overlays (T.B.O.) was investigated by the Colorado Department of Transportation (C.D.O.T) to gage three TBO's performance as an effective protection system. A polyester, an epoxy, and a methyl methacrylate were selected to be evaluated. Each overlay was installed on E-17-QM and monitored for approximately one year. The performance of each overlay was evaluated on: skid resistance, bond strength, resistance to chloride ingress, freeze-thaw resistance, and cost. Skid resistance testing showed that at early ages, each overlay increased the skid resistance of the deck, however after 14 months, each section had skid numbers lower than the bare deck. Chloride tests included testing the profiles of specimens extracted from the deck and from ponded specimens, and from testing the electrical indication of chloride ion penetrability. Physical performance tests included skid resistance, bond strength, and freeze/thaw durability. The MMA proved to be best at preventing the intrusion of chlorides, while Epoxy proved to be the most durable. The short-term results indicate that all three thin bonded overlays can be used as an effective topical protection system to reduce chloride ion ingress and increase the service life of highway bridge decks.