Sulphate resistance of concrete containing fly ash – experiences from laboratory tests and practical applications

Project Number 364

In the next years a lot of construction sites and buildings in Germany are planned and going to be realized in high sulphate environment (soils and groundwater). Because of that the question arise how the sulphate resistance of concrete can be secured in an economical way. The use of fly ash concrete is a promising option. Currently, according to the German standard DIN 1045-2, fly ash concrete can only be used up to a sulphate concentration of 1,500 mg/l in groundwater without further protection. For higher sulphate concentrations additional efforts have to be made or other binders without fly ash have to be used.

As part of this literature research the results of laboratory tests on fly ash containing binders are compiled and compared with high sulphate resistant cements, which can be used up to a sulphate concentration of 3,000 mg/l. Additionally special test conditions, such as the presence of other ions (eg Mg2+), are taken into account. Furthermore the influence of fly ash content variation of the binder on the results is focused. These laboratory test results are compared with field experiments and practical experiences.

Based on this a recommendation for the classification of concretes containing fly ash in terms of sulphate resistance is given.

The project ist supervised by the VGB-Technical Committee “Power Plant By-products”