Dry fly ash is a finely dispersed material usually consisting of particles ranging from under a micron to 0.14 mm.
It has low cementing properties. By settling between larger grains, it reduces the amount of cement required and increases the plasticity and flow properties of concrete. Dry fly ash can also be used to reduce the segregation and improve the workability of a concrete mix, enhance the water and sulphate resistance of concrete, decrease concrete shrinkage and hydration heat of cement, and improve the compressive and flexural strength of concrete.
By replacing cement, dry fly ash reduces the cost of producing construction mortar, improves the properties of concrete and enhances the strength of materials fully immersed in corrosive water (seawater or sulphate water). It is used in the production of aerated concrete, as it makes power-consuming steam treatment unnecessary and reduces the consumption of Portland cement.