Briefing: Re-evaluation of the reliability of hardened concrete analyses

Abstract

As part of the recent revision and update of Concrete Society Technical Report 32, a Concrete Society Working Group organised a laboratory trial in co-operation with 11 laboratories using their UK Accreditation Service-accredited methods for the chemical analysis of hardened concrete. The concrete samples were prepared by Hanson using four mixes, including variously CEM I, pulverised-fuel ash, ground granulated blast-furnace slag, insoluble and soluble aggregates as well as occasionally added chlorides. The findings of the trial were assessed in the second edition of Technical Report 32, which concluded that the trial had limitations but that the results raised concerns about the chemical methods in use. This briefing by three of the participants in the trial who were also members of the Working Group summarises some of its findings and outlines some positive suggestions to address the trial's shortcomings, in order to allow a more realistic and helpful assessment of the methods that have been a vital tool for analysts and engineers for many decades.