Condition Evaluation of Maine Turnpike Bridge Decks
In 2015 Infrasense performed ground penetrating radar (GPR), infrared thermography (IR), and high resolution video surveys to evaluate the condition of 7 bridge decks on the Maine Turnpike. These bridges represent nearly 46,975 square feet along I-95, and all had an asphalt overlay that severely limits the effectiveness of traditional sounding techniques. The GPR surveys were carried out at driving speeds, so no closures were required and traffic flow was not disrupted.
The GPR and IR surveys provide a deterioration quantity and map for each reinforced concrete bridge. The GPR surveys also produced rebar depth and asphalt thickness contour maps for each bridge deck. HNTB will utilize the deck condition results to plan future rehabilitation work on the Maine Turnpike. Infrasense had previously scanned 27 other Maine Turnpike bridge decks, representing over 250,000 square feet, using GPR.
Level 1 evaluations have been carried out for each deck, including determination of estimated deterioration quantities and depths to reinforcement. Tabular summaries of these results have been provided for each work order project. Decks showing significant deterioration levels have been selected for a more detailed Level 2 evaluation, which resulted in maps showing a plan view of delaminated and deterioration deck areas. In the SW region, data from underside visual evaluations has been incorporated into each deck’s evaluation, and the GPR/IR results for each deck were confirmed initially with selective coring and more recently, with non-destructive Impact Echo testing (per ASTM C1383-04).