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Heading: 1.1.1Bottom ash Compositon
Can Bottom ash be use instead of Fly ash inconcrete as subsitute to cement? Does anybody have information about chemical composition of bottom ash? does it have heavy metals?

Mario Bacic

Pulverised fuel ash or fly ash is used as a partial replacement of cement because it is pozzolanic in character. It acquires the characteristics because of the glass content, formed during the coal combustion in the boiler. Bottom ash does not contain glass, hence cannot replace fly ash. However it can be used as fine aggregates in concrete, after removal of carbon and proper testing.

Dr J D Bapat
Dr J D Bapat

My experience with Alberta fly and bottom ash sources indicates that there is little difference chemistry of these materials from a given source. The major difference is the particle size. Fly ash goes up the stack, bottom ash doesn't. The significantly finer fly ash particles are much more chemically reactive and can therefore provide pozzulanic reaction in concrete.
This suggests that, at least in theory, bottom ash could be used in concrete if it was ground to the same particle size as fly ash.
JD (Dave) Robson
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