This document summarizes information about fly ash, including: - Fly ash is a fine powder produced as a byproduct from burning coal in power plants. It is captured by equipment like electrostatic precipitators before flue gases exit chimneys. - It is composed mainly of silicon dioxide, aluminum oxide, and iron oxide, along with small amounts of other elements like arsenic and mercury. It is generally spherical and glassy in shape. - Fly ash has various uses like in bricks, concrete, mine filling, and agriculture due to its pozzolanic properties. It can replace a portion of cement in concrete, improving workability and strength while reducing costs.