EXPLORE CEER

Self-Consolidating Concrete: Applications for Slip Form Paving, Phase 1

Project Investigators

Kejin Wang, Surendra Shah, David White, Bob Steffes

Students

Clinton Halverson, Jiong Hu, Gang Lu, Bekir Yilmaz Pekmezci

Project Schedule

Sep 2004 to Nov 2005

Acknowledgments

Active Minerals, Federal Highway Administration, Iowa Department of Transportation, Kansas Department of Transportation, Nebraska Department of Roads, New York State Department of Transportation, W R Grace, Washington State Department of Transportation

Keywords

compaction, flowability, green strength, longitudinal vibrator trails, overconsolidation, pavement, performance properties, pooled fund study, self-consolidating concrete, slip-form paver, workability

Project Description

Over-consolidation is often visible as longitudinal vibrator trails in the surface of concrete pavements constructed using slip-form paving. Concrete research and practice have shown that concrete material selection and mix design can be tailored to provide a good compaction without the need for vibration. However, a challenge in developing self-consolidating concrete for slip-form paving (SF SCC) is that the new SF SCC needs to possess not only excellent self-compactibility and stability before extrusion, but also sufficient “green” strength after extrusion, while the concrete is still in a plastic state. The SF SCC to be developed will not be as fluid as the conventional SCC, but it will (1) be workable enough for machine placement, (2) be self-compacting with minimum segregation, (3) hold shape after extrusion from a paver, and (4) have performance properties (strength and durability) compatible to current pavement concrete.

The overall objective of this project is to develop a new type of SCC for slip-form paving to produce more workable concrete and smoother pavements, better consolidation of the plastic concrete, and higher rates of production. Phase I demonstrated the feasibility of designing a new type of SF SCC that can not only self-consolidate, but also have sufficient green strength. In this phase, a good balance between flowability and shape stability was achieved by adopting and modifying the mix design of self-consolidating concrete to provide a high content of fine materials in the fresh concrete. It was shown that both the addition of fine particles and the modification of the type of plasticizer significantly improve fresh concrete flowability. The mixes used in this phase were also found to have very good shape stability in the fresh state. Phase II will focus on developing a SF SCC mix design in the lab and a performing a trial of the SF SCC in the field. Phase III will include field study, performance monitoring, and technology transfer.