Field Investigation of High-Performance Concrete Bridge Decks in South Carolina

Abstract

A high-performance concrete (HPC) mixture has been used on several bridge construction projects in the upstate region of South Carolina. The majority of these bridge decks, although not all, have experienced problems with early-age cracking both before being opened to traffic and immediately thereafter. The cracking exhibited in these bridge decks presents a significant obstacle to the widespread adoption of HPC materials for bridges in South Carolina. In an effort to determine likely causes of the cracking experienced in these concrete bridge decks, sight inspections were made of nine bridges in the Greenville-Spartanburg, South Carolina, area, and a thorough review of construction documentation from three of these sites was carried out. In addition, a review of the South Carolina Department of Transportation concrete specifications was conducted. It was concluded that observed cracking has two likely causes. Early-age shrinkage cracking resulted from a rich concrete mixture combined with poor curing practices. Load-induced cracking, appearing shortly after the spans were open to traffic, may result from the placement of relatively stiff decks on more flexible bridge superstructures. Improved on-site quality control and quality assurance are recommended for all aspects of mixing, placing, and curing when HPC is used. It is also recommended that a more appropriate HPC mix design be developed for use in bridge decks. Such a concrete mix would have enhanced durability characteristics and should not be a high-strength mix. Adoption of the eight FHWA performance criteria for HPC is recommended.