Evaluation of Multiple Corrosion Protection Systems for Reinforced Concrete Bridge Decks

Abstract

This study evaluated the corrosion resistance of epoxy-coated (ASTM A775), hot-dip galvanized (ASTM A767), and continuously galvanized (ASTM A1094) reinforcement, and the conventional reinforcement (ASTM A615) used to produce them, as well as ChromX reinforcement (ASTM A1035 Type CS) under the rapid macrocell, Southern Exposure, and cracked beam tests. To simulate the effects of handling, placing, and construction practices in the field, epoxy-coated and galvanized bars were tested in the as-received condition, with intentional damage to the coating, and after bending. To simulate the effects of outdoor exposure on epoxycoated reinforcement, selected epoxy-coated reinforcing bars were tested under accelerated ultraviolet exposure cycles, both without and with physical damage. The corrosion performance of conventional and ChromX reinforcement was also evaluated in conjunction with IPANEX and Xypex, two waterproofing admixtures. Additionally, a 100-year life cost analysis was conducted to compare the cost-effectiveness of the reinforcing bars and admixtures evaluated in providing corrosion resistance based on construction costs in the states of Oklahoma and Kansas. Finally, the effect of variability in corrosion on the predicted service life is investigated using a Monte Carlo simulation using data from conventional, ECR, and ChromX reinforcement from the current study and previous studies.

Epoxy-coated reinforcement exhibited much greater corrosion resistance than conventional reinforcement, even after damage; however, ultraviolet exposure equivalent to as low as 1.2 months of outdoor exposure reduced the effectiveness of the coating resulting in increased corrosion rates. Both A767 and A1094 reinforcement exhibited better corrosion resistance than conventional reinforcement, but corrosion rates on both types of galvanized reinforcement increased when the bars were bent. Xypex was generally effective at reducing the corrosion rate iv of conventional reinforcement, but not ChromX reinforcement; further study is recommended on the effects of Xypex on the corrosion resistance of reinforced concrete. IPANEX did not affect the corrosion resistance of either type of reinforcement. Over a 100-year design life, epoxy coated, galvanized, and ChromX reinforcement are all cost-effective solutions.