This study deals with the laws governing the dispersion of compressive strength values for concrete samples. A survey, carried out at a large number of construction sites, gave the following results: sample strength values show a distribution near the normal Gaussian distribution except when the strength is very low. Generally, test results can be used by means of a scale of probability chart which shows each result deviation immediately (e.g. change in raw materials). The distribution of strength values has a quadratic deviation which can be influenced by the quality of raw materials, manufacturing processes, competence of the personnel, atmospheric conditions, duration of the work and control frequency. The quadratic deviation varies from 10 to 100 kgf/square cm. The quadratic deviation of site concrete increases according to an approximately parabolic law up to a mean strength of 300 kgf/square cm. An equation is derived which expresses the fraction of the quadratic deviation rather than relative dispersion as quality index. In order to standardize safety within a single structure, it is preferable to classify concrete according to a strength probability threshold rather than to adhere to mean strength requirements. A study is made of the quadratic deviation in relation to concrete strength at a 5 percent threshold. In practice, tests should be carried out on random samples rather than on samples prepared in batchs. /IRRD/

  • Corporate Authors:

    Deutscher Ausschuss fuer Stahlbeton

    Berlin-Wilmersdorf,   Germany 
  • Authors:
    • Rusch, H
    • Sell, R
  • Publication Date: 1969


  • German

Media Info

  • Features: Figures; Tables;
  • Pagination: 38 p.
  • Serial:
    • Issue Number: 206

Subject/Index Terms

Filing Info

  • Accession Number: 00081813
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Jul 15 1975 12:00AM