UDC 691.32:006

Gheorghe Croitoru

Abstract. The article presents the problems related to the application of the provisions of the new European standards EN for concrete production, after the withdrawal of the obsolete national standards GOST regarding the correspondence of the classes to the concrete marks. In the context of the application of harmonized standards, there has been a need to establish the correspondence of classes to concrete marks, in order to help design and construction companies to correctly establish the strength mark of concrete to the corresponding class of concrete. The concrete class establishes the normative resistance of concrete for the calculation of constructions, for the service limit state, the prismatic resistance to compression adopted as normative resistance. The ratio between concrete classes and marks, in terms of compressive strength, is determined by the normative coefficient of variation V = 13.5%. The degree of homogeneity of the quality of the concrete is determined according to the values of the standard deviation σ and the average compressive strength of the concrete. As a result of the research, intermediate classes of concrete have been identified, which are not indicated in the normative documents, related to the production of concrete.

Keywords: basic parameters, coefficient of variation, compliance criteria, concrete class, concrete mark, compression strength, correspondence, medium values, standard deviation.

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