For alkali-reactive aggregates that are classified as doubtful (E III-O, E III-OF, E III-S) the Alkali Guidelines issued by the DAfStb (German Committee for Structural Concrete) call for measures that depend on the moisture class of the structural component and the cement content. So far these have involved replacement of the aggregate or the use of cements with a low effective alkali content (low-alkali cements). Performance tests can be used to evaluate the alkali reactivity of a concrete composition in order not to exclude aggregates or cements from use unnecessarily in cases where the Alkali Guidelines specify replacement of the aggregate or the use of low-alkali cement. Performance tests should provide information about whether a concrete composition with a given aggregate and given cement can be used for a certain moisture class so that there is no risk that the concrete will be damaged by an ASR during its planned service life. Performance tests make it possible to provide proof of the suitability of a concrete mix formulation for specific applications. This will allow regionally available starting materials to be used for structural components for which their use had previously been excluded.
In the IGF (Cooperative Industrial Research) project the framework conditions for a possible performance test method for evaluating the alkali reactivity of concrete was calibrated on the basis of the requirements of the German regulations. For this purpose the key points of the regulations for avoiding a damaging ASR were checked systematically. The influence of different types of preliminary storage on the result of performance tests was also be investigated. The aim was to assess the alkali reactivity realistically, especially for concretes made with cements that contain fly ash or granulated blastfurnace slag.
