Recognition of the advantages of being able to judge the the compressive strength of concrete much sooner than by the traditional 28-day test has led to a 50-year search for reliable and convenient accelerated strength testing methods. From within this search, the antecedents of the now standardized CSA and ASTM procedures used in North American are documented together with the pros and cons of each. This analysis led to the selection of the autogenous curing method as an integral part of the concrete quality assurance programme during construction of the Canadian National Communications Tower (CN Tower) in Toronto. The results presented were obtained from 547 sets of cylinders cast during the placing of 40,000 cubic yards (30 580 cu m) of slipformed concrete to a height of 1,500 feet (457 m) between July 1973 and February 1974. They indicate that the 90-day compressive strength of the concrete made with either low heat or normal Portland cements or a blend thereof can be predicted as easily from 2-day autogenous strength results as it can be from 28-day strengths. Procedures for monitoring the adequacy of the protection provided during winter slipform concrete construction using concrete strength/maturity concepts are documented in support of the essential role of accelerated strength determination in the control of quality and the overall structural safety of the concrete shaft of the world's tallest freestanding structure.

  • Corporate Authors:

    Ontario Ministry of Transportation & Communic, Can

    Research and Development Division, 1201 Wilson Avenue
    Downsview, ONo M3M 1J8,   Canada 
  • Authors:
    • Smith, P
    • BICKLEY, J A
  • Publication Date: 1974-10

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 15 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00142204
  • Record Type: Publication
  • Report/Paper Numbers: RR 204 Conf Paper
  • Files: TRIS
  • Created Date: Feb 16 1977 12:00AM