Study for the Avoidance of a Concrete-damaging Alkali Silica Acid Reaction by Use of Fly Ash
Project Number 226
During the production of concretes with alkali-sensitive additives, an upper limit value for the effective alkali content of all concrete additives of 600 g/m3 is to be kept according to the current alkali guideline of the DAfStb (1997). The effective alkali content of fly ash is to be determined with 1/6 of the total alkali content of the fly ash. This limit value does not permit the use of fly ash in self compacting concrete with the usual dosages. That means, during the production of self compacting concrete with alkali-sensitive additives fly ash is in fact to be excluded.
The study is to lead to a re-valuation of the effective alkalis in fly ashes and thus, to a utilisation of the positive effects of fly ashes regarding the alkali silica acid reaction. The results serve to expand the use of fly ash in concrete with alkali-sensitive addivites.
Under the management of Prof. Stark the project is to be carried out between July and November 2002 at the building material institute, Bauhaus University in Weimar. The Working Panel "Power Plant By-products" is supporting the examination technically.