What are natural accelerators in building materials?

1. Fly ash: Fly ash is a finely divided residue resulting from the combustion of powdered coal. It can be used to improve the strength, durability, and volume stability of concrete and mortar.

2. Ground granulated blast furnace slag: This material is a by-product of the iron and steel industry, which is then ground into a fine powder. It is used as an admixture to improve concrete’s mechanical properties and durability.

3. Metakaolin: This is a very fine grade of calcined clay, which reacts with cement when it is hydrated to form calcium silicate hydrates, reducing water demand and increasing strength and setting times.

4. Silica fume: This is a by-product of silicon and ferrosilicon alloy production and is composed of very fine particles about one-hundredth the size of ordinary cements particles. It increases strength and reduces permeability when added to concrete.

5. Natural pozzolans: These include materials such as volcanic ash and shale, which contain silica and alumina. When react with cement, they produce calcium silicate hydrates, reducing water demand and increasing strength.