ADMITTING THAT CHLORIDES ARE VARIABLE!

This article reports the results of the authors' investigation of the quality control problems, experienced by some laboratories that estimate the chloride content of concrete. The generally accepted test method for chloride in hardened concrete is described in British Standard BS 1881 Part 124. Two types of faster and more precise methods, based on ion-selective electrodes, are now available. Whatever method is chosen, the key to good accurate results is regular checking of standards of known composition. Samples, with chloride contents of 0.0%, 0.05%, 0.1%, 0.23%, and 0.45% were sent to twelve laboratories in the UK, mostly well known, and mostly National Measurement Accreditation Service (NAMAS) accredited for testing. The results of the test were not good; only five laboratories reported results within 10% nominally, and the others showed significant errors. The best defence against this is to submit one's own control samples alongside the samples being tested. Alternatively, but less effectively, the laboratory should be asked to report its control results with sample test results, to ensure: (1) sufficiently frequent tests; (2) covering the range of chloride in the samples; and (3) tests of appropriate types. NAMAS is aware of these problems, and is currently considering what action to take.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/09670726
• Corporate Authors:

  PALLADIAN PUBLICATIONS LTD

  THE OLD FORGE
  ELSTEAD, SURREY  United Kingdom  GU8 6DD
• Authors:
  • GRANTHAM, M
  • VAN ES, R
• Publication Date: 1995

Language

• English

Media Info

• Features: References;
• Pagination: p. 7-8,10
• Serial:
  • CONSTRUCTION REPAIR
  • Volume: 9
  • Issue Number: 6
  • Publisher: PALLADIAN PUBLICATIONS LTD
  • ISSN: 0967-0726

Subject/Index Terms

• TRT Terms: Concrete; Electrodes; Errors; Halides; Laboratories; Organizations; Quality assurance; Samples; Standards; Test procedures
• Geographic Terms: United Kingdom
• ITRD Terms: 4755: Concrete; 6951: Electrode; 6440: Error; 7314: Halide; 6237: Laboratory (not an organization); 9057: Organization (association); 9123: Quality assurance; 6251: Sample (mater); 187: Specification (standard); 6288: Test method; 8119: United Kingdom
• Subject Areas: Terminals and Facilities;

Filing Info

• Accession Number: 00723187
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD
• Created Date: Jul 26 1996 12:00AM