CONCRETE SPECIFICATION - WHAT PRICE QUALITY ASSURANCE?

The author critically examines the value of quality assurance in relation to concrete specifications. He outlines the British Standard (BS 5328) and CP 110 Criteria and discusses the relative merits of methods using random numbers. His method of assessment was to take groups of 50 consecutive 28-day cube results as they came up, for concrete of grade C20 and above. Results were processed by computer to obtain mean, standard duration and the notional value of characteristic strength giving exact statistical compliance with a maximum 5 per cent defective basic standard. The computer then compared each test result with the characteristic strength and the BS compliance C-3 figure. It also compared averages of running fours with the BS compliance C+3 figure. This was done for 100 groups of results. Details of results are given and the variability discussed. Results indicate that the BS compliance criteria entail such a high risk of rejection, that the supplier has to aim at a much higher standard than 5 per cent defectives and that nil C+3 rejects do not assure that the defective rate is within 5 per cent. The author points out that the BS method is non-definitive and needs simple meaningful statistical methods to fully understand results, and that much work still needs to be done to establish proper guidelines. /TRRL/

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  • Corporate Authors:

    Department of the Environment

    Room 1640 Lunar House, 40 Wellesley Road
    Croydon CR9 2EL,   England 
  • Authors:
    • Shallcross, A G
  • Publication Date: 1976-9

Media Info

  • Features: Figures; Tables;
  • Pagination: p. 27-29
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00149036
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • ISBN: 0 117244 21
  • Report/Paper Numbers: Analytic
  • Files: ITRD, TRIS
  • Created Date: Jun 17 1977 12:00AM