SERVICE LIFE OF IOWA BRIDGE DECKS REINFORCED WITH EPOXY-COATED BARS

In an effort to minimize corrosion of the reinforcement in bridge decks, the Iowa Department of Transportation started using epoxy-coated rebars as top reinforcing mat around 1976. However, the presence of cracks in bridge decks has raised some concerns among bridge and maintenance engineers. The impact of deck cracking on the service life of a bridge deck was investigated herein. This was accomplished by collecting core samples from 80 bridges, calculating the chloride content in these cores, developing a relationship for chloride infiltration through the deck, examining the condition of several rebar samples, developing a rebar rating-age relationship, and estimating bridge deck service life. No signs of corrosion were observed on the rebars collected from uncracked locations. In addition, no delaminations or spalls were found on the decks where bars at cracked location exhibit some signs of corrosion. Considering a corrosion threshold for epoxy-coated rebars that ranges from 3.6 lb/cu yd to 7.5 lb/cu yd (2.19 kg/cu m to 4.56 kg/cu m), the predicted service life for Iowa bridge decks was over 50 years.