Quantifying the Impact of Cover Deficiencies on Bridge Deck Service Life: Recommendations for Contracting
Sponsor: Georgia Department of Transportation
Project Information
PI: Lauren Stewart, Co-PI: Kim Kurtis
Student: Leonidas Emmenegger
Dates: August 1, 2017 - Feb 21, 2020
Funding: $175,000
Summary
Bridges are critical structures, serving an important function vital to the safe and economical conveyance of people and goods throughout Georgia. However, construction of reinforced concrete bridge decks with shallower or deeper-than-specified concrete cover remains an ongoing challenge for GDOT because it leads to reductions in service life. Shallow cover shortens service life in bridge decks through earlier incidence of corrosion and more rapid degradation during corrosion. Cover depth that is too deep leads to cracking in the decks, which then also contributes to degradation by corrosion, salt scaling, and/or freeze/thaw cycling. Premature degradation results in the necessity for more frequent inspections, earlier and additional maintenance and repair, and eventually, reconstruction. These activities have negative consequences on traffic (and create an associated economic impact), in addition to reducing ride quality and bridge safety.
Currently, no formal financial incentives or consequences exist for contractors and associated parties that construct a bridge deck that does not meet the design cover requirements dictated in the Georgia concrete bridge deck specification. In the coming years, it is anticipated that GDOT will contract to place 150 to 200 bridge decks, making improvements in the contracting for this construction a vital topic to address at this time. This project will: (1) quantify the impact of deeper-than or shallower-than-specified concrete cover thickness on service life, (2) review contracting arrangements used by other state and federal agencies as well as private entities, (3) make recommendations for warranties, liquidated damages and/or penalty clauses based on reduction in service life due to various levels of insufficient cover considering variations in service environment and criticality of structure, and (4) make recommendation to GDOT for contracting mechanisms for bridge deck construction based upon performance.