U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
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Publication Number: FHWA-HRT-06-078
Date: June 2006
Job Site Evaluation of Corrosion Resistant Alloys
APPENDIX A FHWA Project Number DE-00-01
TEA-21 INNOVATIVE BRIDGE CONSTRUCTION PROGRAM
State DOT Contact: Mr. Keith Gray [(302) 760-2327].
Bridge Number: 1-119.
Project Type: Deck Replacement.
Location: Bridge on SR 82 crossing Red Clay Creek in Ashland, New Castle County, DE.
Innovative Material: MMFX-II reinforcing steel.
Bridge Description: The bridge is a relatively short, historical, single span structure on a secondary roadway. As such, no deicing salts have normally been employed. Deterioration of the old deck involved concrete cracking and other distress that was apparently a consequence of freeze-thaw damage. The reinforcing steel (conventional black) was said to have been in good condition. Initially, stainless steel clad reinforcement was specified; but because of delivery problems, this was changed to MMFX-II. The project consisted of a full deck replacement and painting of the existing steel girders. The approach roadway was repaved, and new steel beam guardrails (polyester coated brown) were placed. The guardrail was attached to new barrier walls that were constructed adjacent to the existing barrier. This was designed to match the historic architecture of the existing barrier. The existing alignments and roadway widths were maintained. Figure 6 shows a side view of the bridge and of Red Clay Creek, while figure 7 is a photograph of the deck prior to concrete pouring but with the MMFX-II reinforcement in place.
Innovation Justification: The bridge is subject to application of deicing salts, and chloride levels in the old deck were extremely high. It was considered that specification of a corrosion-resistant reinforcement in the replacement deck would reduce maintenance costs and extend the life of the bridge.
Construction Sequence: The contractor’s construction sequence for the deck replacement involved the following sequential steps:
Figure 8 shows a general view of the in-place reinforcement, including that for the curb along one of the railings. Also shown are the girders and welded shear studs. Figure 9 provides a view of forming for the bulkhead at the other bridge end. A closer view of reinforcing bars and a girder with welded shear studs is shown in figure 10. The longitudinal and transverse bars are #5s, with spacing for the former being 10 inches and the latter, 12 inches. Figure 11 is also a closeup view of the in-place reinforcement showing superficial rusting. The steel had been onsite for approximately 20 days with rain having occurred during much of this time. This corrosion was judged to be less than what would have occurred with conventional uncoated black steel.
Reinforcement Specification: Delaware DOT (DelDOT) did not have a material specification because, first, the use of MMFX-II steel was a field change and, second, the product is new. The design was based upon properties of conventional steel, and it was considered that the higher strength of MMFX-II would provide a further factor of safety.
Concrete Specification: The concrete was DelDOT Class D, “Deck Concrete,” the mix design for which is given in table 6. Slab thickness varied from 10.5 inches at the center to 8.5 inches at the outside. Design cover over the reinforcement was 2.5 inches.
*pcy = pounds per cubic yard; **cy = cubic yards
Greggo and Ferrara, Inc.
4048 New Castle Avenue
New Castle, DE 19720
Steel Supplier: MMFX Steel Corporation of America, Inc. Subsequent to FHWA approval for substituting MMFX-II for stainless steel clad reinforcement, the contractor contacted MMFX-II directly to determine cost and availability. Straight bars were shipped to the contractor’s steel fabricator (ReSteel) where cuts and bends were made. ReSteel then shipped the bars directly to the job site. There were no delays or delivery problems in acquiring the MMFX-II reinforcing steel.
Material Cost: The MMFX-II material cost for 8.79 metric tons was $15,120 for a unit price of $0.78/lb ($1.72/kg). The in-place reinforcing steel cost was $2.95/lb ($6.49/kg).
Job Site Storage: The reinforcing steel was delivered elevated on a flatbed truck and stored elevated and uncovered on the ground.
Material Acquisition: Six bent bar details were made available from the job storage site for testing by FAU and FDOT. Figure 12 shows a photograph of these.
3The description for this bridge utilizes English and not metric units since the project documents and specifications were so based.