ABSTRACT
The examination and compression testing of cores cut from hardened concrete is a well-established method, enabling visual inspection of the interior regions of a member to be coupled with strength estimation. Other physical properties which can be measured include density, water absorption, indirect tensile strength and movement characteristics including expansion due to alkali-aggregate reactions. Cores are also frequently used as samples for chemical analysis following strength testing. In most countries standards are available which recommend procedures for cutting, testing and interpretation of results; BS EN 12504-1(135) in the UK, whilst ASTM C42 (136) and ACI 318 (137) are used in the USA. It must be noted however that the above new European Standard offers no guidance on planning or interpretation, although a further document dealing with this is in preparation. Extremely valuable and detailed supplementary information and guidance is also given by Concrete Society Technical Report 11 (36) and its addendum, which are related to the former British Standard (BS 1881: Part 201 – now withdrawn). A UK National Annex to BS EN 12504-1 is also in preparation dealing with allowances for voidage, reinforcement, maturity and direction of drilling, and this is likely to reflect the Concrete Society guidance. The Concrete Society have also published the results of extensive field experiments aimed at enhancing interpretation in terms of estimated cube strengths for different cement types, member types and construction conditions (138). Interpretation is a potentially complex process and Neville (139) has recently reviewed many of the issues involved including sampling and testing planning.
