Fly Ash Pozzolanic Cement

Fly ash is a byproduct of coal combustion that acts as a powerful pozzolan. When mixed with cement and water, it reacts with calcium hydroxide to produce additional Calcium Silicate Hydrate ($C-S-H$) gel, which strengthens the concrete. It is categorized into Class F and Class C. Fly ash reduces permeability, increases long-term strength, and improves workability due to the spherical shape of its particles (the ball-bearing effect). It also lowers the heat of hydration, preventing thermal cracking in mass concrete structures.