Cement is the most cost and energy-intensive component of concrete. The unit cost of concrete can be reduced by partial replacement of cement with fly ash. Accordingly, the replacement of cement with fly ash reduces the unit cost of the concrete, and conserves energy. In concrete, the replacement of cement with fly ash has the beneficial effects of lower

The advantages of adding fly ash in cement are

Reduced heat of hydration:-  Replacing cement with the same amount of fly ash can reduce the heat of hydration of concrete. This reduction in the heat of hydration does not sacrifice long-term strength gain or durability. The reduced heat of hydration lessens heat rise problems in mass concrete placements.

Decreased water demand:- The replacement of cement by fly ash reduces the water demand for a given slump. When fly ash is used at about 20 percent of the total cementitious, water demand is reduced by approximately 10 percent. Higher fly ash contents will yield higher water reductions. The decreased water demand has little or no effect on drying shrinkage/cracking. Some fly ash is known to reduce drying shrinkage in certain situations.