Air-entrained Concrete Advantages

Air-entrained Concrete Advantages

Entrained air produces discrete cavities in the cement paste and therefore reduces passage of capillary water. It improves the workabillty because the air bubbles kept special by the surface tension, act as fine aggregate of low surface friction and considerable elasticity. Air entrainment of concrete reduces segregation, bleeding, permeability and formation of laitance. But if lowers the density of the concrete then it is liable to shrinkage on drying. Air entrained concrete is frost resistant. This type of concrete is mainly recommended for used in dams, bridges , tunnels and for roads in extremely cold countries and sulfate bearing soils.
There are some disadvantages along with the advantages of air-entrained concrete. For every 1% increase in air, the compressive strength of concrete will be reduced by 2-6%.


Air entrainment is the deliberate creation of bubbles of air in concrete. The number of such air cells per cubic foot of concrete can be measured in the billions. This is done by addition of agents that entrain air and are generally chemicals. The air bubbles are produced when the concrete is mixed and continue to be a part of the concrete even after it hardens. Normal concrete will have small capillaries produced by the evaporation of the water in the concrete. These capillaries are invaded by water from the environment and the freezing of this water can cause a lot of stress in concrete because of the expansion in volume that accompanies the freezing. This causes further cracks and continued deterioration in the concrete. Air entrained concrete allows the expansion to take place without causing any further stresses, as the air bubbles are capable of being compressed. The bubbles also contribute to the workability of the concrete.