The Contractor’s Perspective

This paper describes how the use of high performance concrete (HPC) on the Wacker Drive Reconstruction project presented several special challenges to the general contractor. Some of these resulted from the concrete mix proportions while others resulted from the special provisions. The first challenge was the erratic air content following the addition in the field of the high-range water-reducer (HRWR). During the first weeks of production, the addition of the HRWR would cause the air content to either increase or decrease, with no apparent pattern. Further, the required dosage of air-entraining admixture to achieve the specified 5.5 to 8.5 percent air content was not consistent from one day to the next. The second issue was what to do when the air content was too high. Typically, high air content of concrete can be reduced by additional mixing, or by stopping the truck's drum completely for a time. However, the HPC on this project seemed reluctant to release entrained air regardless of these, or any other techniques. Although the start of HPC production was a little rough, the contractor simply rode out the learning curve. After which, working with the HPC was no different from any other concrete. Everyone grew accustomed to the HPC with its special requirements and construction never seemed to be hampered due to the mix.

• Corporate Authors:

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590

  National Concrete Bridge Council

  Portland Cement Association, 5420 Old Orchard Road
  Skokie, IL  United States  60077-1083
• Authors:
  • Schultz, Kyle
• Publication Date: 2005

Language

• English

Media Info

• Media Type: Print
• Features: Photos; Tables;
• Pagination: 2p
• Monograph Title: HPC Bridge Views
• Serial:
  • HPC Bridge Views
  • Issue Number: Issues 1-38
  • Publisher: National Concrete Bridge Council
  • Serial URL: http://www.hpcbridgeviews.org

Subject/Index Terms

• TRT Terms: Admixtures; Air content; Air entrained concrete; Bridge design; Concrete structures; Contractors; Mix design
• Identifier Terms: Wacker Drive (Chicago, Illinois)
• Geographic Terms: Chicago (Illinois)
• Subject Areas: Bridges and other structures; Construction; Highways; I50: Construction and Supervision of Construction;

Filing Info

• Accession Number: 01111246
• Record Type: Publication
• Files: TRIS, USDOT
• Created Date: Sep 24 2008 10:39AM