Fly ash


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Related to Fly ash: fly ash concrete, Silica fume

fly ash

[′flī ‚ash]
(engineering)
Fine particulate, essentially noncombustible refuse, carried in a gas stream from a furnace.
Coal combustion residue.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Fly ash

A fine glass powder recovered from the gases of burning coal during the production of electricity. It is an ash residue from high-temperature combustion processes. Electric motor plants using western coal produce a nontoxic fly ash that because of its very high calcium content can be a substitute for Portland cement, the common bonding material in concrete, and these micron-sized Earth elements consist primarily of silica, alumina, and iron. When mixed with lime and water, fly ash forms a cementitious compound with properties very similar to that of Portland cement. Because of this similarity, fly ash can be used to replace a portion of cement in the concrete, providing some distinct quality advantages. The concrete is denser, resulting in a tighter, smoother surface with less bleeding. Fly ash concrete offers a distinct architectural benefit with improved textural consistency and sharper detail. Regulations vary from state to state; however, ASTM International suggests that fly ash must not contain more than 6 percent unburned carbon to be used for its cementitious qualities. Substitution of fly ash for Portland cement in concrete is considered a sustainable building strategy, as it reduces the amount of energy-intensive (and CO2-producing) cement in the mix.
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved

fly ash

The finely divided residue resulting from the combustion of ground or powdered coal, transported from the firebox through the boiler by flue gases.

fly ash

as the aggregate.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
Fly ash combines with calcium hydroxide to produce additional cementitious materials, thereby reducing the amount of calcium hydroxide that may be leached out of the concrete.
"At present, 63 percent of the fly ash is being utilised, and target is for 100 percent utilisation of the fly ash.
Fly ash waste was collected from the cyclone overflow of the fluidized bed circulating-type boilers of the Bayer process at conditions of 900[degrees]C of temperature and 120 kPa of pressure.
Effect of Fly Ash on the Concentration of Free Nitrite Ion.
In this research, pure cement and ordinary fly ash were used as a reference.
In the present investigation, fly ash, an industrial waste, was used as the adsorbent for the adsorption of reactive blue 25 dye from aqueous solutions.
Vegetation cover development on fly ash disposal sites is difficult at early stages.
While some researchers have used fly ash in concrete, they have not been able to eliminate the intense heating methods that traditionally are needed to make a strong material.
Higher durability is guaranteed with fly ash because its reaction with cement allows for the design of concrete strength on a par with industry standards (28-day test).
Consumption of fly ash by region and list of manufacturers
The power plants are capable of producing more than one million tons annually of concrete quality Class F fly ash that will be offered for distribution through Boral's extensive western United States network.