Categories of admixtures
Admixtures stand for the special ingredients. In order to improve the conditions and operation of fresh concrete, they are included throughout concrete mixing. Different types of admixtures are applied in construction work.
FUNCTION OF ADMIXTURES:
1. To speed up or slow down the setting time of fresh concrete.
2. To make the applicability or flowability of concrete better.
3. To improve the strength and longevity of concrete.
4. To minimize the heat of hydration.
5. To lessen the segregation and bleeding.
6. To reduce the permeability.
7. To obtain other optimal properties.
CATEGORIES OF ADMIXTURES:
1. ACCELERATING ADMIXTURES:By adding this admixture to concrete or mortar, for increasing the rate of hydration of hydraulic cement is raised as well as setting time is reduced. Calcium chloride (CaCl2) is mostly recognized as accelerating admixture.
2. RETARDING ADMIXTURES:Retarding admixtures postpone the preliminary rate of hydration of cement and lengthen the setting time of cement paste. This admixture is useful for high temperature and where the concrete should be transmitted to a long distance. It can also be utilized for grouting oil wells.
3. AIR-ENTRAINING ADMIXTURES:With air entraining admixtures, it is possible to generate a specific amount of air bubbles in the concrete mixture. The admixture can enhance the resistance capacity toward freeze-thaw degradation and cohesion. The workability of fresh concrete is also enhanced devoid of modifying the setting or the rate of hardening.
4. WATER REDUCING ADMIXTURES:Include water reducers to a concrete mixture, mortar or grout for raising the flowability devoid of augmenting the water content.
Benefits Of Water Reducing Admixtures:
1. The rate of concrete placement becomes speedy.
2. Strength, longevity, density etc. considerably get better.
3. Segregation, permeability, and cracking are significantly minimized.
SPECIAL ADMIXTURES:
1. Superplasticizing admixtures.
2. Corrosion-inhibiting admixtures.
3. Grouting admixtures.
4. Coloring admixtures etc.
