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Materials and Structures

, Volume 31, Issue 4, pp 242–246 | Cite as

A proposal for the prediction of the characteristic cube strength of concrete from tests on small cores of various diameters

  • F. Indelicato
Scientific Reports

Abstract

A method is proposed for the assessment of characteristic cube strength, fck, based on tests performed on 28 mm diameter microcores, small 45 mm diameter cores, and 70 mm diameter cores. In particular, on the basis of the tests performed on the specimens (1270 between cubes and cores of the three diameters being considered, manufactured from 16 concrete types), relationships are defined which make it possible to estimate mean cube strength,\(\bar f_c\), with, a desired confidence level (1−α)%, starting from a mean core strength,\(\bar f_{28} ,\bar f_{45,} \bar f_{70} \). Subsequently, given a number of microcores, n28, n45, n70, subject to compressive tests the proposed method makes it possible to determine the number of cubes nc necessary to evaluate the mean cube strength with the same confidence level, and characteristic strength with a good approximation. Finally, having worked out the one-side tolerance factor, k, fck is evaluated with the aid of the estimated value of\(\bar f_c\), the calculated value of k, and an estimate of the mean standard deviation on cubes, s c , as determined from the core tests.

Keywords

Nondestructive Test Characteristic Strength Concrete Strength Diameter Core Small Core 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Résumé

On présente une méthode d’évaluation de la résistance caractéristique sur cube,f ck , sur la base d’essai sur des microcarottes de 28 mm de diamètre, de petites carottes de 45 mm de diamètre et sur des carottes de 70 mm de diamètre. Notamment, sur la base des essais réalisés sur 1 270 éprouvettes (des cubes et des carottes des trois diamètres mentionnées ci-dessus, fabriquées à partir de 16 bétons différents), on établit des rapport qui permettent d’estimer la résistance moyenne sur cube\(\bar f_c\) avec un niveau de confiance voulu (1−α)%, à partir des résistances moyennes sur carottes\(\bar f_{28} ,\bar f_{45,} \bar f_{70} \). Ensuite, sur la base d’un certain nombre de microcarottes,n 28,n 45,n 70, soumises à l’expérimentation, on obtient le nombre de cubesn c nécessaire pour estimer avec le même niveau de confiance les résistances moyennes sur cube et, avec une bonne approximation, les résistances caractéristiques. Enfin, après avoir obtenu le facteur de tolérance unilatéralek, on calcule la valeur estimée def ck à l’aide la valeur estimée de\(\bar f_c\), de la valeur calculée dek, et d’une estimation de l’écart quadratique moyen sur les cubes,s c , obtenue des essais sur carottes.

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Copyright information

© RILEM 1998

Authors and Affiliations

  • F. Indelicato
    • 1
  1. 1.Department of Structural EngineeringPolitecnico di TorinoTurinItaly

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