Air-entrained cement is a special cement which has air bubbles introduced in the cement or concrete that provides the space for expansion of minute droplets of waters in the concrete due to freezing and thawing and protects from cracks and damage of concrete.
Advantages
- Workability of concrete increases.
- Use of air entraining agent reduces the effect of freezing and thawing.
- Bleeding, segregation and laitance in concrete reduces.
- Entrained air improves the sulphate resisting capacity of concrete.
- Reduces the possibility of shrinkage and crack formation in the concrete surface.
Disadvantages
- The strength of concrete decreases.
- The use of air entraining agent increases the porosity of concrete thereby reducing the unit weight.
- Air-entrainment in concrete must not be done if the site control is not good. This is due to the fact that the air entrained in a concrete varies with the change in sand grading, errors in proportioning and workability of the mix and temperatures.
