Processed pulverized fuel ash for high-performance concrete

Research, quality control and market introduction have resulted in full utilization of pulverized fuel ash (PFA) in the Netherlands. Because of more stringent environmental regulations, the demands of the building industry and increasing competition of by-products from other industries, continuous effort is needed to facilitate the marketing of the by-products. In this paper an approach to research on by-product utilization is discussed. This is illustrated by some new developments such as classification and micronization of PFA. Air classification proved to be an appropriate technique for separation of fly ash into various size fractions. By removing the coarse size fraction from fly ashes, a significant improvement of concrete properties can be achieved. The receipts and properties of the examined concrete mixtures with micronized, ultrafine PFA are equal to high-performance concrete with micro-silica. The workability, the compressive strength and the durability of the mixtures and concrete with micronized PFA are equal to high-performance concrete. Taking into account the production costs and the market prices for ultra fines it seems to be profitable to produce micronized PFA for the production of high-performance concrete.