Abstract
Generally, a determination of the water-cement ratio (w/c) of hardened concrete is not very useful, but there exist indirect methods for that purpose. A direct method, utilizing optical fluorescence microscopy, has been standardized by a Nordic organization; it requires the use of reference standards of a range of mixes with specific ingredients and a known curing history. The method is useful for quality control in repetitive production of concrete elements.
A recent paper claims that the w/c of unknown concrete can be determined with a precision of ±0.02. A review of that paper, utilizing simple statistical tests, shows that the claim is unfounded, so that caution in the use of optical fluorescence microscopy is required.
Résumé
En général, la détermination du rapport eau-ciment du béton durci est peu utile, mais il existe des méthodes indirectes dans ce but. Une méthode directe, qui utilise la microscopie optique de fluorescence a été normalisée dans les pays nordiques; elle requiert l'utilisation des normes de référence avec un éventail de mélanges de béton ayant une composition spécifique et un traitement connu. La méthode est utile dans le contrôle de la production d'éléments en béton.
Une récente publication prétend que le rapport eau-ciment d'un béton inconnu peut être établi avec une précision de ±0.02. Une étude de cette publication basée sur des essais statistiques démontre qu'une telle précision n'est pas bien fondée; par conséquent, une grande attention est nécessaire dans l'utilisation de la microscopie optique de fluorescence.
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References
Neville, A., ‘How useful is the water-cement ratio?’,Concrete International 21 (9) (1999) 69–70.
‘Analysis of hardened concrete’, Technical report Vol. 32 (Concrete Society 1989) 110.
St John, D.A., Poole, A.W. and Sims, I., ‘Concrete petrography’ (Arnold and John Wiley, London and New York, 1998).
Bate, S.C.C., ‘Report on the failure of roof beams at Sir John Cass's Foundation and Red Coat Church of England Secondary School, Stepney’, Current paper 58 (Building Research Establishment, 1974).
‘Building code requirements for structural concrete’, ACI 318 (American Concrete Institute 1999).
‘Définition et détermination du rapport eau sur ciment’,Societé suisse des ingénieurs et des architectes 7 (April 1999) 128–129.
‘Concrete, hardened: water-cement ratio’,Nordtest method, NT Build 361 (Nordtest 1991-02).
Mayfield B. ‘The quantitative evaluation of the water/cement ratio using fluorescence microscopy’,Magazine of Concrete Research 42 (150) (1990) 45–49.
‘A real world application of the MTU w/c standards’, Michigan Technological University at www.cee.mtu.edu/~krpeters/wc/watercement1.html and also watercement3.html and watercement4.html (March 01).
Jakobsen, U.H., Laugesen, P. and Thaulow, N. ‘Determination of water-cement ratio in hardened concrete by optical fluorescence microscopy’, in ‘Water-Cement Ratio and Other Durability Parameters—Techniques for Determination’, Editor M.S. Khan (SP-191, ACI, Michigan, 2000) 27–41.
Neville, A.M., ‘Objectivity in citing references’,Materials de Construcción 51 (263–264) (2001) 29–35.
Elsen, J.et al., ‘Determination of the w/c ratio of hardened cement paste and concrete samples on thin sections using automated image analysis techniques’,Cement and Concrete Research 25 (4) (1995) 827–834.
Kennedy, J.B. and Neville, A.M., ‘Basic statistical methods for engineers and scientists’, Third Edition, (Harper and Row, New York, 1986).
Neville, A.M., ‘Properties of concrete’, Fourth Edition (Longman and John Wiley, London and New York, 1995).
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Neville, A. How closely can we determine the water-cement ratio of hardened concrete?. Mat. Struct. 36, 311–318 (2003). https://doi.org/10.1007/BF02480870
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DOI: https://doi.org/10.1007/BF02480870