Title: Impact of Shrinkage Reducing Admixture on Properties and Performance of Bridge Deck Concrete

Author(s): J. J. Schemmel, J. C. Ray, and M. L. Kuss

Publication: Symposium Paper

Volume: 189

Issue:

Appears on pages(s): 367-386

Keywords: admixtures; air-entraining; bridge decks; cracking; durability; properties

DOI: 10.14359/5862

Date: 1/1/2000

Abstract:
The impact of a Shrinkage Reducing Admixture (SRA) on the properties and performance of conventional concrete was investigated. The SRA studied was a commercially available glycol ether blend. Tests were conducted on two structural air-entrained concretes commonly used in bridge deck construction. The SRA dosage rate was varied between 1.0% to 2.0%, by weight of cement. Influence of the SRA on fresh concrete properties, compressive strength development, unrestrained shrinkage, and freezing and thawing durability was examined. It was determined that the SRA has a slight effect on initial workability and a moderate impact on compressive strength development. Free shrinkage was reduced on the order of 50%. The freeze-thaw durability of some SRA mixtures was found to be below generally accepted limits. This behavior was traced back to problems associated with maintaining entrained air. It was discovered that the SRA mixtures tended to lose air more rapidly than the control mixtures. Further, petrographic analyses suggest that the air content in hardened SRA concrete may be noticeable less than that measured in fresh concrete. Strategies to over come this problem are proposed.