Corrosion Resistant Alloy Steel (MMFX) Reinforcing Bar in Bridge Decks

011151592007PDFTech ReportR-1499Bridge decksCorrosion resistanceEpoxy coatingsLife cycle costingLoad and resistance factor designHighwaysBridges and culvertsCorrosion resistant alloysCorrosion resistant steelReinforcing materialsMichiganUnited StatesMichigan. Dept. of TransportationKahl, SteveMichigan. Dept. of TransportationUS Transportation CollectionEpoxy coated reinforcement (ECR) has gained mainstream acceptance since the early 1980s as a means to extend the useful life of highway structures. Research to date estimates additional service life between 5 to 15 years is provided by the epoxy coating. To achieve a 75 year service life, however, alternate materials must be considered. Typically, the only alternative to ECR has been the use of more expensive corrosion resistant materials, such as stainless steel. Another alternative, MMFX reinforcement, has potential to resist corrosion and yet remain economical in initial cost to use. Corrosion resistance, mechanical properties, and design criteria were investigated with MMFX reinforcement. The MMFX steel does exhibit corrosion resistance, higher yield strength, and a lower life cycle cost than ECR. The bond strength for MMFX was comparable to uncoated reinforcement, but results from flexure testing of reinforced concrete beams imply that the lap length needs further study. Therefore, the designer should reduce or eliminate lapped joints, either by mechanical splices, or requiring the contractor to supply the exact length reinforcing bars as detailed on the plan sheets. Due to the high yield strength, MMFX use in bridge deck construction should be limited to structures that are designed in accordance with AASHTO LRFD code, and for 75 ksi steel reinforcement design yield strength, in highly congested urban areas, when life cycle costs are justified.92