FLY ASH AND USAGE IN TURKEY

9th International Multidisciplinary Scientific GeoConference - SGEM2009, www.sgem.org, SGEM2009 Conference Proceedings/ ISBN 10: 954-91818-1-2, June 14-19, 2009, Vol. 2, 751-756 pp

ABSTRACT

Fly 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.

Keywords: Fly Ash, Concrete, Portland Cement, Lightweight Concrete, Cement Floor Tiles, Clay Bricks