Assessment of the Compressive Strength of Concrete in a Structure in Cases of Doubt as to its Compliance with the Established Requirements

Introduction. When assessing the strength of concrete based on standard tests, there may be doubts about its compliance. The procedure for assessing the strength of concrete in such cases is carried out in accordance with GOST R 57360-2016 (Russian Federation) and STB EN 13791-2012 (Republic of Belarus). Fundamentally different approaches to assessing concrete strength are contained in EN 13791-2019 (introduced in 2020), many provisions of which differ significantly from the previous version and are new to specialists who monitor concrete strength during the construction stage and during the inspection of reinforced concrete structures.

Materials and Methods. The object of the study is a section of a concrete or reinforced concrete structure where the concrete strength is assessed when there is doubt about its compliance with established requirements. In such cases, the following concrete tests are conducted: preliminary indirect testing; indirect testing followed by the selection and testing of concrete specimens by the direct method from areas with the lowest concrete strength; testing of concrete specimens by the direct method.

Research Results. Information is provided on the selection of test areas and sites, their number, methods of core sampling and assessment of compressive strength of concrete based on the results of core testing, combined tests, including the indirect method and core testing. An analysis of concrete strength evaluation methods is performed in cases of doubt as to the compliance of concrete with the established requirements.

Discussion and Conclusion. The paper presents the fundamental differences in the methods for assessing the strength of concrete in structures in cases of doubt as to the compliance of concrete with the established requirements provided in in the European standard and the national standards of Russia and the Republic of Belarus. The disadvantages of the methodology set forth in EN 13791-2019 are outlined.

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