The Use of Fly Ash in Concrete - A European View

Abstract

AbstractA European view of the use of fly ash in concrete, if there is one, is very confused. Mehta [1] produced figures for the production and utilisation of fly ash in the cement and concrete industries for 1984, ranging from 10% utilisation in the UK where the cement makers are not enthusiastic, to 80% in the Federal Republic of Germany and even 94% in the Netherlands according to Fraay, Bijen, de Haan and Larbi [2]. Looking a little deeper into these figures the CEGB Ash Marketing Board says that it sells over 40% of its production of fly ash of some 14 million tons/year, much of it for landfill, while the figures for Germany relate only to the 2.6–2.9 million tons of ash from black coal; 70% of the German ash comes from brown coal, and all of this is returned to the open-pit mine for dumping. This paper will review some of the European papers in the Third CANMET/ACI International Conference on Fly ash, Silica Fume, Slag and Natural Pozzolans in Concrete held in Trondheim in June 1989 and some more recent work funded by the Ash Marketing Division of CEGB at Imperial College and the Building Research Establishment, Garston. Four specific aspects of the effects of fly ash on concrete will be considered: rheology and workability; the pozzolanic reaction and the effects of curing; the development of microstructure; and the development of strength and some aspects of durability.