Korrelation von Betondruck‐ und Zugfestigkeit historischer Betone

Correlation between the compressive and tensile strength of old concretes – Applicability of the relationship described by DIN EN 1992‐1‐1 In the design of a new structure, DIN EN 1992‐1‐1 [1] normatively regulates the correlation between the compressive strength and tensile strength of concrete, produced according to DIN EN 206‐1 [2]. However, as there are many different time‐ and load‐dependent impacts on existing structures, the relationship described by DIN EN 1992‐1‐1 [1] can't be assumed without any further observations for existing structures. At the moment, there is no comprehensive investigation on the influences of e.g. subsequent hardening and carbonation on the concrete compressive or tensile strength. The tensile strength of concrete defined in DIN EN 1992‐1‐1 [1] is based on a water storage and a testing age of 28 days. Furthermore, the in‐situ tensile strength is affected by micro‐crack formation cause of internal stresses due to outflow of hydration heat. Generally, there is a different influence of micro‐crack formation on the tensile strength of concrete than on the compressive strength of concrete. The real value of the in‐situ tensile strength of concrete affects the shear force resistance and the load‐bearing capacity of anchors with concrete cone failure as decisive failure mode. Within the framework of a research project, financed by ”Forschungsinitiative Zukunft Bau“, an initiative of the Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBR) structural investigations on the correlation between the compressive and tensile strength of old concretes have been performed. Below, the results of the research project are presented.