BOND CHARACTERISTICS OF OVERLAYS PLACED OVER BRIDGE DECKS SEALED WITH HMWM OR EPOXY

The reported research examines the bond strength between overlays placed over bridge decks which are sealed with epoxy resin or high molecular weight methacrylate (HMWM) sealers. The study involved field and laboratory experimental testing of cores under direct shear, Strategic Highway Research Program (SHRP) interfacial specimens, beams, and a 1/3-scale bridge subassembly of a typical steel stringer bridge. Micro-silica modified concrete, latex modified concrete, and superplasticized dense concrete overlays were used in this study. The experimental data were complemented with finite element studies. Despite often stark variations in the values of bond strength obtained from different testing methods, the data universally suggest that the use of a sealer at the interface can reduce the available bond strength. The level of the strength reduction depends on the type of sealer, but the bond strength can drop by as much as 50%. Extra surface preparation techniques, such as light sandblasting of the surface after applying the sealer or broadcasting sand over the sealed interface while the sealer is curing, are effective in restoring the bond strength. Sandblasting the HMWM sealed surface, or broadcasting sand [at approximately 100 kg/sq m (20 lb/sq ft)] increases the strengths to 80% and 85%, respectively, of the unsealed surfaces. Fatigue testing and loading well beyond service level loads do not adversely impact the bond strength so long as the sealed surface is treated before the application of the overlay. Test results indicate that bond strength at the overlay-deck interface is not critical when the deck is subjected to negative moments (i.e., those producing tension in the overlay); hence, the deck over piers can be sealed with or without a secondary treatment of the sealed surface. Although the application of sealers lower the available bond strength, finite element analyses of representative bridges show that the maximum computed shear stress is smaller than the lowest strength. Therefore, bridge decks may be sealed if either of the recommended secondary surface preparation techniques is followed to prepare the sealed deck before the application of overlays.

• Record URL:
  • https://ntlrepository.blob.core.windows.net/lib/21000/21700/21778/PB99140865.pdf
• 
• Corporate Authors:

  University of Cincinnati

  Department of Civil and Environmental Engineering
  Cincinnati, OH  United States  45221-0071

  Ohio Department of Transportation

  Office of Materials Management, 1600 West Broad Street
  Columbus, OH  United States  43223-1298

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Shahrooz, B M
• Publication Date: 1998-7

Language

• English

Media Info

• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 195 p.

Subject/Index Terms

• TRT Terms: Adhesive bond strength; Bridge decks; Concrete overlays; Epoxy resins; Field tests; Finite element method; Laboratory tests; Sand blasting; Seal coats; Sealing compounds; Shear stress; Surface preparation
• Uncontrolled Terms: High molecular weight methacrylate
• Subject Areas: Bridges and other structures; Design; Highways; Maintenance and Preservation; I24: Design of Bridges and Retaining Walls; I61: Equipment and Maintenance Methods;

Filing Info

• Accession Number: 00763212
• Record Type: Publication
• Report/Paper Numbers: FHWA/OH-98/022,, Final Report
• Contract Numbers: State Job No. 14604(0)
• Files: NTL, TRIS, ATRI, USDOT, STATEDOT
• Created Date: May 7 1999 12:00AM