The following is an excerpt from the Western Region Ash Group website: “fly ash is the very small particle mineral residue that results from the burning of powdered coal in utility boilers. The individual particles are very small, like talcum powder, and are carried up and out of the boiler in the flow of exhaust gases leaving the boiler after the coal is consumed. Hence the term “Fly Ash”. The Fly Ash particles are removed from the stack gasses using Electrostatic Precipitators, Flue Gas Desulphurization (FGD) systems or Bag Houses and are collected and stored dry for recycling.
“Fly Ash is a pozzolan: a silica, alumina, and calcium based material which, in the presence of water, will chemically combine with the free lime contained in the fly ash and produces a cementitious material with excellent structural properties.
“Fly Ash can be used as a direct replacement for Portland cement in making concrete, in addition to many other applications.”
Benefits of using fly ash in concrete:
- Pozzolanic properties reduce need for cement
- Spheres act like ball bearings, increasing workability
- Fills in voids with cementitious material and acts as filler, reducing
total surface area to be covered with cement
- Increased strength with age