Question:
What is the status on the use of self-consolidating concrete in bridges?
Answer:
Self-consolidating concrete (SCC) is a highly workable concrete that flows easily into the formwork and around congested reinforcement without segregation. SCC has been used extensively for bridges in Japan and Europe. Interest in its use in the United States has increased rapidly in recent years because SCC results in better consolidation, less bug holes, less manpower, less noise, less time for placement, and less maintenance cost of equipment.
A 2003/2004 survey by FHWA indicated that 36 percent of the states responding had made changes in the last 10 years to accommodate the use of SCC and 17 percent included it in their current specifications. A recent survey by North Carolina State University indicated that 55 percent of the states responding had used SCC in precast and/or prestressed concrete products but only within the last four years. Several states responded that they have ongoing research projects into its use. An article about its use for a bridge in Maine appeared in HPC Bridge Views, Issue No. 33.
In August 2004, the National Cooperative Highway Research Program Project 18-12 was initiated to develop guidelines for the use of self-consolidating concrete in precast, prestressed concrete bridge elements and to recommend relevant changes to the AASHTO LRFD bridge design and construction specifications. These guidelines are expected to provide highway agencies with the information necessary for considering concrete mixtures that are expected to expedite construction and yield economic benefits. Concurrently, other research is ongoing at several universities to support state implementation.
As owners become more confident in the use of SCC and producers and contractors become more knowledgeable about the material, its use is expected to increase. HPC Bridge Views is interested in learning about SCC applications in specific bridges.
More Information
PCI National Bridge Conference, October 16-19, 2005 session on SCC.
SCC 2005, Second North American Conference on the Design and Use of Self-Consolidating Concrete, October 30-November 2, 2005.
Interim Guidelines for the Use of Self-Consolidating Concrete in PCI Member Plants, TR-6-03, Precast/Prestressed Concrete Institute.
ERRATA
HPC Bridge Views No. 38, Page 3, Table on Concrete Mix Proportions: The correct values of water reducer and HRWR are 98.7 fl oz (3818 mL) and 49.4 fl oz (1911 mL), respectively.