Abstract

Considering the pervasive presence of chlorides in concrete bridge decks, bridge engineers have a critical responsibility to perform proper and effective preventive maintenance and rehabilitation operations. Bridge engineers often perform scarification and overlay (SO) procedures on concrete bridge decks to minimize the corrosion of reinforcing steel due to chloride ingress. Given the need to develop guidelines for the initial timing of SO treatments, the specific objectives of this research were to collect information from several department of transportation (DOT) personnel about their SO procedures and, subsequently, to determine the recommended timing of initial SO procedures on concrete bridge decks for preventing the accumulation of corrosion-inducing levels of chlorides and extending deck service life. A questionnaire survey of state DOTs was conducted, and numerical modeling of SO treatments was performed. Simulations involving both decks with and without stay-in-place metal forms (SIPMFs) were performed. Numerical modeling was performed for each unique combination of variables through a service life of 50 years to determine the recommended initial timing of SO treatment in each case. The research results show that, overall, bridge decks without SIPMFs can endure longer delays in SO treatment timing than those with SIPMFs; in all cases, the absence of SIPMFs extended the amount of time before an SO treatment was needed. For decks with SIPMFs, the allowable delay in SO timing ranged from 2 to 6 years, while on decks without SIPMFs the allowable delay in SO timing ranged from 6 to 18 years. These delays are only 1 to 3 years longer than allowable delays associated with placement of surface treatments investigated in previous research. On average, the period of additional delay allowed before an SO treatment is required in decks with SIPMFs was 2 years with each additional 0.5 in. of OCD. In decks without SIPMFs, the presence of a greater OCD had a more pronounced effect on the latest recommended timing of treatment than in the decks with SIPMFs; an average additional delay period of 5 years was obtained with each additional 0.5 in. of OCD in decks without SIPMFs. Together with the findings of this research and the specific properties of the bridge deck under scrutiny, engineers can determine the appropriate timing of rehabilitation procedures to prevent or mitigate corrosion of the steel reinforcement of a bridge deck and ensure the usability of the deck for its intended service life. Although the conditions studied in this research were consistent with bridges located in the state of Utah, bridge decks that exist in similar environments and that are subjected to similar treatments of deicing salts as part of winter maintenance could exhibit similar properties to the decks simulated in this research. Engineers should carefully consider the results of this research and implement proper timing of SO treatments on their respective bridge decks to protect against and minimize the effects of corrosion due to chloride ingress.

Degree

MS

College and Department

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

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2008-11-19

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd2662

Keywords

concrete bridge decks, stay-in-place metal forms, scarification, overlay, surface treatment, rehabilitation, maintenance, treatment timing, bridge, deck

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