Scholarly record

FLY ASH AND USAGE IN TURKEY

A. Ilgun, U. S. Yilmaz, S. K. Akin, M. T. Cogurcu, M. S. Donduren

Abstract

ly ash is one of the residues generated in the combustion of coal. Fly ash is generally captured from the chimneys of coal-fired power plants, all fly ash includes substantial amounts of silicon dioxide (SiO2) (both amorphous and crystalline) and calcium oxide (CaO). In the past, fly ash was generally released into the atmosphere, but pollution control equipment mandated in recent decades now requires that it be captured prior to release. Total amount of fly ash produced at coal-fired power plants is about 450 million tons/year in the world and only 6\% of it is used instead of cement in concrete. The amount of fly ash produced in Turkey is about 15 billion tons/year in 11 coal-fired power plants. The recycling of fly ash has become an increasing concern in recent years due to increasing landfill costs and current interest in sustainable development. Two classes of fly ash are defined by ASTM C618: Class F fly ash and Class C fly ash. The main difference between these classes is the amount of calcium, silica, alumina, and iron content in the ash. The chemical properties of the fly ash are largely influenced by the chemical content of the coal burned (i.e., anthracite, bituminous, and lignite). Fly ash is used as a replacement for some of the Portland cement content of concrete and its chemical and physical properties effects the properties of concrete directly. In this study mechanical effects of fly ash usage instead of cement are investigated in lightweight concrete structural elements, square cement floor tiles, clay bricks.

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