Fly Ash of Pulverised Fuel Ash is a by-product of coal-fired power stations. It is a fine material with spherical particles. Uses include as an additive in composite cements, as a cementitious component in concrete and as a filler in certain types of asphalt.

Various test methods are specified in BS and EN Standards and include the determination of moisture content, water requirement, strength, loss-on-ignition, initial setting time, and soundness. These tests are based on those described in BS EN196. A major requirement for Fly Ash is consistency of fineness.