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.

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.

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.
References in periodicals archive ?
These pre-washed samples of fly ash were further chemically treated with 10% concentrated sulfuric acid [27] for 12 hours and then washed finally with distilled water to eliminate the surplus amount of acid through filtration process.
Portland Cement (PC) was replaced partially by fly ash at replacement levels of 5%, 10%, 15%, 20%, 25% and 30% respectively by total binder weight.
Fly ash, when mixed with sandy soils, can also provide nutrients.
Fly ash was added to concrete directly as percentages of 40%, 50% and 60% by weight of cement.
Fly ash and gypsum were mixed by hand until the homogeneity of the FA-G blends was achieved.
So-called high-volume fly ash "ternary" mixtures (including some limestone) that replace between 40 percent and 60 percent of the cement portion not only set at rates comparable to those for typical concrete, but also were superior in terms of key properties.
18 letter to Henderson obtained by The Sun, Wastech general manager Janet Tecklenborg indicated that fly ash from the Burnaby waste incinerator, before treatment "contains enough heavy metals with phosphoric acid and lime to be classified as hazardous waste.
The loss-on-ignition (LOI) test was used to determine the unburned carbon, especially in the fly ash sample.
The production of bottom ash + fly ash and water of 1:1 mass-ratio is made by the mixing equipment.
For the better management of fly ash waste from thermal power plants across country, Government has reduced the GST rates on fly ash and its products to 5%.