Suitability of fly ash with higher loss on ignition (LOI) for the use as con-crete addition

Project Number 373

Due to changes in basic conditions regarding the operation of hard coal fired power plants the quality of fly ash in some power plants (in Germany) tends towards higher LOI (loss on ignition) values.

Within this research project the question of a use of such ashes (LOI category B or C according to DIN EN 450) in concrete should be answered from a technical and “historical” point of view considering different regulations in Europe.

On one hand the impact of fly ash with higher LOI on fresh and hardened concrete properties, like the water demand, the compressive strength development or the interaction with concrete admixtures, is focused.

On the other hand the reasons for the definition of the LOI limit of 5 % (category A) in Germany should be examined and compared to other European Countries. This is done by literature research.

Based on the results of the literature research a recommendation for the use of fly ash with higher LOI as concrete addition will be possible.

The research project is supervised by the VGB-Technical Committee “Power Plant By-products”.