Job Site Evaluation of Corrosion-Resistant Alloys for Use as Reinforcement in Concrete
Primary Topic: Materials-General
Description: Premature deterioration of the Nation's concrete highway and bridge structures as a consequence of chloride (salt) exposure and resultant corrosion of reinforcing steel has evolved during the past four decades to become a formidable technological and economic problem. In response to this, epoxy-coated reinforcing steel (ECR) was adapted in the mid-1970s as a proactive measure to control this problem. Premature corrosion-induced cracking of marine bridge substructures in Florida indicated, however, that ECR is of little benefit for this type of exposure; and while performance of ECR in northern bridge decks has been generally good to date (30-plus years), still the degree of corrosion resistance to be afforded in the long term to major structures with design lives of 75-1 00 years is uncertain. Corrosion-resistant reinforcements, including stainless steels, are an alternative for such applications, and a component of the Federal Highway Administration (FHWA) Innovative Bridge Research and Construction Program addressed incorporated of such reinforcements into approved State bridge construction projects. The present project evaluated a selected number of these in terms of the type of reinforcement used and difficulties and advantages that were encountered. Of the 27 approved State projects for which information could be gathered; 20 were either completed as planned or utilized an alternate corrosion-resistant reinforcement. The different reinforcements types were solid Types 31 6 (3 projects), 2201 LDX (1 project), and 2205 (5 projects) stainless steels, Type 316 stainless clad black bar (3 projects), MMFX-II (13 projects), and galvanized steel (3 projects). In some cases, more than one corrosion-resistant reinforcement was used on a single project. The various State projects demonstrated that, subject to availability, corrosion-resistant reinforcing steel can be incorporated into bridge construction with relative ease and placed with less difficulty than ECR. Thus, these reinforcements are a viable technical alternative to ECR. Realizing the full benefit of this IBRC program, however, will depend upon individual States acquiring performance data and maintaining records on these structures for decades into the future.
FHWA Publication Number: FHWA-HRT-06-078
Publication Year: 2006