Practical testing of the alkali reactivity of concrete compositions of the WF and WA moisture classes in ASR performance tests

摘要

An alkali silica reaction (ASR) can damage concrete and reduce the intended service life of concrete structures. In this situation the serviceability can sometimes only be retained by expensive repairs. Damaging ASR will not occur if the aggregate is sufficiently non-reactive to alkalis, the concrete is sufficiently dry or the effective alkali content in the pore solution of the concrete is appropriately low. The alkalis come from the constituents of the concrete composition, predominantly the cement, and in some cases from de-icing agents that can penetrate into the concrete from outside. The Alkali Guidelines of the DAfStb (German Committee for Structural Concrete) [1] specify measures that have to be applied in Germany for concrete compositions complying with DIN EN 206/DIN 1045-2 in order to avoid ASR damage. The measures are specified in relation to the following parameters: 1. alkali reactivity class of the aggregate 2. moisture class of the concrete element 3. cement content of the concrete composition.