THE EFFECT OF CURING CONDITIONS AND CUBE SIZE ON THE CRUSHING OF CONCRETE

THE CRUSHING STRENGTH OF A CONCRETE CUBE DEPENDS NOT ONLY ON THE MIX CONSTITUENTS AND ON THE AGE AND CURING HISTORY BUT ON THE SPECIMEN SIZE AS WELL. THIS REPORT DESCRIBES EXPERIMENTS TO MEASURE THE EFFECT OF CUBE SIZE ON THE STRENGTH OF CEMENT PASTES, MORTARS AND CONCRETES. CUBES FROM 50 TO 150 MM WERE USED. FOR WET-CURED SPECIMENS, THERE IS A SUBSTANTIAL DECREASE IN CRUSHING STRENGTH AS THE CUBE SIZE IS INCREASED FOR THE STRONGEST MIXES USED, THE DIFFERENCE TENDING TO INCREASE WITH STRENGTH LEVEL BUT THE WEAKER MIXES DID NOT SHOW ANY SIZE DEPENDENCE. BREAKAGE MECHANISMS BASED ON STATISTICAL CONCEPTS CAN BE USED TO ACCOUNT FOR SIZE EFFECTS BUT THE SIMILARITY IN LOAD-DEFLECTION BEHAVIOR FOR DIFFERENT STRENGTH MIXES DID NOT ENABLE A CLEAR DISTINCTION TO BE MADE BETWEEN CONCRETES THAT WERE SIZE-DEPENDENT AND THOSE THAT WERE NOT; HOWEVER, LATERAL STRAIN MEASUREMENTS PROVIDE SOME EVIDENCE THAT DISTINGUISHES BETWEEN THE PROGRESSIVE FAILURE OF STRONG AND WEAK CONCRETES. THE DRYING HISTORY IS SHOWN TO AFFECT THE SIZE RELATIONSHIPS; PREMATURE DRYING OF SMALL CUBES BEFORE HYDRATION HAS PROGRESSED FAR AND NOT ONLY LIMITS THE STRENGTH DEVELOPMENT BUT MAY ALSO REDUCE THE STRENGTH AS SURFACE CRACKS ARE FORMED; THE RESULT IS THAT SMALL CUBES ARE UP TO 20% WEAKER THAN LARGE ONES. THE IMPLICATIONS OF THE EXPERIMENTS ARE DISCUSSED AND THE VALUE OF THE DELIBERATE USE OF SPECIMEN SIZE TO HIGHLIGHT ENVIRONMENTAL EFFECTS IS EMPHASIZED. /AUTHOR/

  • Supplemental Notes:
    • APP
  • Corporate Authors:

    Cement and Concrete Association

    52 Grosvenor Gardens
    London SW1W 0AQ,   England 
  • Authors:
    • Pomeroy, C D
  • Publication Date: 1972-7

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 18 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00214200
  • Record Type: Publication
  • Report/Paper Numbers: No 42.470 Tech Rept
  • Files: TRIS
  • Created Date: Oct 16 1973 12:00AM