Influence of Ultrafine Fly Ash on Shrinkage and Cracking Tendency of Concrete and the Implications for Bridge Decks

Early age shrinkage cracking of concrete bridge decks is a major concern to the transportation industry, including construction contractors and state DOTs. The repair of concrete bridge decks is expensive and difficult. The most cost effective solution is to prevent cracking from occurring in the first place by carefully selecting proper ingredients for bridge deck concrete. Selection of the material for a bridge deck requires proper understanding of how the material influences the shrinkage cracking potential of concrete. This paper describes an experimental study that was performed in order to understand the influence of ultrafine fly ash (UFFA) on the shrinkage cracking of concrete mixtures. The paper provides a relative comparison of the performance of concrete containing UFFA with that of concrete containing silica fume (SF). Several mortar mixtures were prepared with varying UFFA and SF content. Free shrinkage strain and splitting tensile strength measurements were performed using standard test methods. In addition, the restrained ring test was used to determine the residual tensile stress development in concrete ring specimens. The cracking potential of the mixtures was assessed by computing simple ratios of the residual tensile stress in the rings and the splitting tensile strength of the mixtures. The results of this study favored the use of UFFA in bridge deck concrete because concrete containing UFFA demonstrated significant reduction in both shrinkage and shrinkage cracking potential. Conversely, the concrete containing SF demonstrated higher level of shrinkage and higher cracking potential.

Language

  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; References; Tables;
  • Pagination: 15p
  • Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

Filing Info

  • Accession Number: 01045569
  • Record Type: Publication
  • Report/Paper Numbers: 07-0022
  • Files: PRP, TRIS, TRB
  • Created Date: Feb 8 2007 4:35PM