Applied utilisation of fly ashes from pulverised coal combustion in the European construction industry

The utilisation of fly ashes from pulverised coal fired power plant in different products of the European construction industry is already well established and common practice. The proposed paper will give an overview about already existing and possible wands of an economic fly ash utilisation in Europe. Therefore, available annual quantities and their distribution into different product streams will be analysed. Additionally, typical results of the analysis of chemical compositions of power plant residues and the effect on construction properties of different fly ash components will be shown. In comparison with requirements on quality and characteristics of fly ashes being relevant for the quality and performance of different construction products recommendations and guidelines for a proper fly ash utilisations can be defined. In particular, for the utilisation as air additive to concrete these requirements are given in the European standard EN 450 " Fly ash for concrete-Definitions I requirenients and quality control". Furthermore, the paper will show influences of secondary fuel co-combustion in pulverised coal boiler on the composition and therefore quality of the resultant fly ashes. Since the utilisation of fly ashes in concrete, regulated by tire European Standard EN 450, is actually only allowed for pure coal combustion the current situation forms an economic obstacle for the application of combustion technology due to fly ash utilisation. A first step to eliminate this obstacle is air actually ongoing revision of the standard EN 450 to include the possibility to utilise fly ashes from co-combustion as aggregate for concrete. Therefore, results front a actually ongoing European research project entitled: "Utilisation of residues from biomass co-combustion in pulverised coal boilers" will be presented and discussed. The Objective is to support the running standardisation activities with a broad set of fly ash data prepared from experimental combustion tests of coal and different secondary fuels in lab and full scale combustion facilities.