Bottom Ash
Bottom ash is agglomerated ash particles, formed in pulverized coal furnaces, that are too large to be carried in the flue gases and impinge on the furnace walls or fall through open grates to an ash hopper at the bottom of the furnace. Physically, bottom ash is typically grey to black in color, is quite angular, and has a porous surface structure.
Bottom ash is coarse, with grain sizes spanning from fine sand to fine
gravel. Bottom ash can be used as a replacement for aggregate and is usually
sufficiently well-graded in size to avoid the need for blending with other
fine aggregates to meet gradation requirements. The porous surface structure
of bottom ash particles make this material less durable than conventional
aggregates and better suited for use in base course and shoulder mixtures
or in cold mix applications, as opposed to wearing surface mixtures. This
porous surface structure also makes this material lighter than conventional
aggregate and useful in lightweight concrete applications.
Bottom ash applications include its use as a:
- Filler material for structural applications and embankments
- Aggregate in road bases, sub-bases, and pavement
- Feed stock in the production of cement
- Aggregate in lightweight concrete products
- Snow and ice traction control material