WHAT IS FLY ASH?

'Fly ash is a by-product of coal power plants. It consists of very small, condensed glass spheres of coal particles collected in electrostatic precipitators. It is an industrial solid waste that can be used as raw material for other applications. Its use in concrete is beneficial to the environment, yields cost reductions, energy savings, and improves durability.

Fly ash enhances different properties of concrete thanks to its pozzolanic activity. As a pozzolan, fly ash in the presence of moisture chemically reacts with lime (CaOH) at regular temperatures and creates calcium silicate hydrate (C-S-H), which is a durable cementitious compound. Hydration of portland cement (PC) generates calcium silicate hydrate (C-S-H) and free lime (CaOH). The addition of fly ash (FA) will create more cementitious material (C-S-H), as it combines with the free lime. . . .The mineralogical characteristics and the shape, size and texture of fly ash particles influence its pozzolanic and cementitious properties far more than the chemical composition...'