The amount of fly ash in concrete can vary from 10% to 30% by mass of the cementitious materials. Dosage depends upon the source and composition of the fly ash and the performance requirements of the concrete. Proportion of fly ash is based on project requirements, local practice and concrete design mix. Typical dosage of fly ash are given below:
- 10% to 20%: By weight of cement but as an addition not replacement
- 15% to 30%: High durability/ Low permeability such as bridge decks or parking structures
Mixing And Handling
Caution must be used in exposed fly ash applications, as concrete or mortar-containing fly ash is darker than standard concrete.
Fly ash is fine and dust may cause eye and respiratory irritation. Use good industrial hygiene practices (i.e. wear goggles and approved usage dust mask).