Vermeidung von schädigender AKR durch Steinkohlenflugasche

Up to now the use of alkali sensitive aggregate is permitted by German regulations only in combination with low-alkali cements, i.e. Portland and blast furnace cements with low effective alkali contents. For many years, the use of binders containing fly ash has been considered as a possible way of avoiding damaging reactions. This method has already been introduced into international regulations and guidelines, but not in Germany. This is because the performance of fly ash with available German materials has, up to now, not been systematically investigated. The present results show that the use of fly ash as specified by DIN EN 450 does not add ASR active alkalis to concrete. It could be proved that if the binder contains sufficient fly ash, damaging ASR is prevented in concrete made with slowly reacting dense aggregate.