Der Altersexponent für die Dauerhaftigkeitsbemessung von Beton unter Chlorideinwirkung Teil 1

The ageing exponent for the durability design of concrete exposed to chlorides part 1: Basics and determination of the ageing exponent

For the concept of durability design of concrete under chloride exposure, engineering models are used to describe the diffusion-based chloride transport. The binder-dependent ageing exponent of the concrete is one of the decisive parameters. It describes the time-dependent decrease in the apparent chloride diffusion coefficient, and thus, the long-term development of the material resistance of concrete. This article first deals with the prediction model for describing the chloride ingress into concrete in the combination with the explanation of the ageing exponent. The focus is on the description of the various methods available in the literature for determining the ageing exponent. These methods are based on laboratory and/or on-site investigations. The choice of method has a significant influence on the ageing exponent and thus on the durability design of the concrete. In addition, the ageing exponent is a decisive parameter for classification when implementing the concept of exposure resistance classes (ERC) in accordance with prEN 1992-1-1. The two-part publication is intended to contribute to the uniform evaluation of the chloride penetration resistance of concrete. The first part deals with the principles and procedures for determining the ageing exponent, while the second part explains the influences on the ageing exponent using calculation examples.