Most reinforced concrete decks in Ohio on steel beams or prestressed I-beams are 8- 1/2" thick and may or may not have a bonded concrete overlay (1- 3/4" or 1- 1/4" thick) or an asphalt concrete overlay (2- 1/2" thick).
Reinforced concrete bridge decks built prior to 1975 probably contain black (uncoated) reinforcing steel, while most built since 1975 contain epoxy coated reinforcing steel. Since the corrosion of the uncoated reinforcing steel and subsequent spalling (delamination) of the cover concrete was a huge problem in the early 1970's, the introduction of an epoxy coating on the reinforcing steel has largely eliminated the spalling (delamination) problem. Since there is still some concern about the long- term life of epoxy coated reinforcing steel (even though epoxy- coated reinforcing steel has already exceeded the average life of uncoated steel by 3 times), ODOT decided to adopt a more impermeable concrete in early 1990's called high performance concrete (HPC). The combination of epoxy- coated reinforcing steel and HPC should result in decks which will last at least 50 years.
Experience in Ohio has shown virtually no difference in the deterioration rate of a reinforced concrete deck whether on top of steel beams or prestressed I-beam bridges, although it is recognized that steel beam bridges are more flexible than prestressed I-beam bridges and therefore could be more prone to transverse cracks in the deck. The same can be said of reinforced concrete slab bridges, which derive strength from a thick cross-section and do not have underlying beams. These are very rigid (minimal flexibility), but they also seem to deteriorate at about the same rate as steel beam bridges. The following recommendations will therefore pertain to reinforced concrete decks on:
Steel-beam bridges (rolled beams or built-up girders).
Concrete-beam bridges (pre-stressed I-beams or box beams)