Literature Study: Sulphate Resistance of Fly Ash Concrete
Project Number 254
Concrete components, which are exposed to a sulphate attack, can be damaged by expansion due to secondary formation of ettringit and/or gypsum. Additionally, they can be damaged by the formation of thaumasite at low temperatures of the concrete components. According to the existing legislation, concretes with high sulphate resistance are to be used to avoid damages.
The resistance of concrete to sulphate attacks results from of a chemical and a physical resistance. The used cement and/or the used cement fly ash combination is the most important factor for the chemical resistance, for the physical resistance the structural density, which is steared by the water cement ratio and the type of cement. The evaluation of sulphate resistance of cement and/or of a cement fly ash combination has been examined on the basis of time lapse laboratory tests so far. However, regarding the evaluation of the test results, these tests are discussed controversial because unfavourable binders according to laboratory tests show high sulphate resistance in practise.
The internationally existing experience on production and examination of sulphate resistant binders/concrete shall be compiled within the literature study. The results serve the fundamental estimation of a further regulation demand for the German concrete standards.
The project is carried out by the Institute of Building Materials and Construction at the Technical University of Munich, under the management of Prof. Detlef Heinz. The results of the study will be published in a status report of the German committee for reinforced concrete (DAfStb).