One of the most important aspects of the use of fly ash in concrete is the fact that, in general, the use of fly ash markedly improves the properties of freshly mixed concrete.

In the available documentation, there is broad agreement as to the effect of fly ash and the importance of the decisive influencing parameters. Opinions still differ, however, as to the physical causes of the observed effects. The following observations based on practical experience with concrete containing fly ash are reported: — Replacing cement by fly ash reduces the water demand of the concrete /B10 , B 46,

B 47, B 55, E 2,F 2, G 5, G 16. K 37, K 38, L 23, L 33, S 7, V 2, V 3, V 5, W 4/. — The use of fly ash improves concrete pumping or in some cases is a necessary

prerequisite for it / G 9, H 21, W 5, J 23, K 37/. — The workability and, especially, the compactability, flowability, and plasticity of

concrete are generally improved / B 1, B 55, G 9, J 1, K 38, L 8, L 27, M 3, R 15, W 5 / .