PREDICTING THE 28 DAY COMPRESSIVE STRENGTH OF CONCRETE AT AN AGE OF 24 HOURS

IT IS USUAL TO WAIT 28 DAYS BEFORE CHECKING THE STRENGTH OF CONCRETE, WHICH MAY VARY FROM THE DESIGNED STRENGTH AS A RESULT OF VARIATIONS IN THE CHARACTERISTICS OF THE CONSTITUENT MATERIALS. THE NATIONAL BUILDING RESEARCH INSTITUTE (NBRI) HAVE DEVELOPED A METHOD (BASED ON OVERSEAS RESEARCH WORK) WHICH ENABLES 28DAY STRENGTH TO BE PREDICTED FROM THE RESULTS OF TESTS MADE AFTER ONLY 24 HOURS. DETAILS OF THE METHOD ARE GIVEN WHICH INVOLVE CURING FOR 4 HOURS, IMMERSING IN COLD WATER AND HEATING TO 80 DEGREES C IN 1 HOUR, CURING AT 80 DEGREES C FOR 19 HOURS AND TESTING. THE COMPRESSIVE STRENGTH AFTER THIS PROCEDURE HAS BEEN FOUND TO CORRELATE WITH 28 DAY STRENGTH (AND IS ABOUT 60 PERCENT OF THIS VALUE). DETAILS ARE GIVEN OF A SUITABLE APPARATUS. 90 PER CENT OF THE NBRI'S PREDICTED VALUES WERE WITHIN 15 PER CENT OF THE 28 DAY STRENGTH. A GRAPH SHOWS THE RELATION THAT WAS FOUND BY NBRI, BUT IT IS RECOMMENDED THAT OTHER WORKERS PREPARE THEIR OWN GRAPHS.

  • Corporate Authors:

    National Institute for Road Research, South Africa

    P.O. Box 395
    Pretoria, Transvaal,   South Africa 
  • Publication Date: 1973-5

Media Info

  • Features: Figures; References;
  • Pagination: 4 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00081931
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: NBRI X/BOU2-17 R&D Rpt.
  • Files: ITRD, TRIS
  • Created Date: Apr 8 1975 12:00AM