Adjustment of the expression of compression strength of concrete in structures according to NC standard 1109

Abstract

The compressive strength of concrete is a property that is essential to know in constructions that are in progress, as well as constructions in the process of rehabilitation, in structures that suffer accidents and that demand reconstruction actions and in constructions in operation that have had increases in the usage loads. Determining this property involves various difficulties, such as the impossibility of extracting cores in the elements under study without affecting the structure. To avoid this, engineering has developed non-destructive procedures, such as sclerometry and ultrasound, which used independently, are not accurate enough to estimate compressive strength. An international practice is to use both types of tests, non-destructive and destructive, by making regression equations to estimate the compressive strength from the former. In Cuba, this procedure is regulated by the NC 1109 standard, which has its own regression equation. However, the authors of this article show that this equation is not sufficiently exact and that there are others that are more suited to the conditions of the country. Precisely, the article compares the behavior of the equation regulated in NC 1109 of 2015, with the general equation of the combined SONREB method applied in other countries, as a result of which a new regression equation is obtained from the data analyzed.