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Concrete Admixtures

Concrete Admixtures 

Concrete has some initial and final setting time and hence it is required to be put into the formwork. For better efficiency, there are some concrete admixtures that help in many ways to increase the time or reduce the time for setting and in workability with less water/cement ratio and many other situations.

the different types of Concrete admixtures
Admixture added Concrete


Various Admixture:

1. Retarders Admixtures :

Retarders are used to slow down the chemical reaction between water and other ingredients that takes place when concrete starts the setting process. These types of admixtures are used to reduce the effect of temperature that increases the speed of setting and thus reduces the required strength.
  • Mainly used in the concrete pavement where finishing time is required more.
  • Some retarders help in reducing cracks formation in the concrete work.

2. Accelerating Admixtures :

Accelerating concrete admixtures are used to increase concrete strength development and reduce the setting time.
  • Accelerating admixtures are used for the modification of concrete in cold weather.
  • Adequate cover and proper concrete mix can solve the corrosion problem

3. Air Entraining Admixtures :

An Air Entraining Admixture increase the freeze-thaw durability of concrete. Also due to this admixture, the workability is increased with reduced segregation and bleeding in the fresh stage. 
  • It improves the resistance of concrete to frost action. 
  • Gives a high degree of workability and durability.

4. Plasticizers :

Water-Reducing admixtures help in lowering the water/cement ratio than what it is normally designed. Also, reduces the carbon dioxide emission. The concrete properties are improved and with less water/cement ratio it also gives higher slump value which helps to retain the grade of concrete with the same workability.
  • It lowers the cement content which results in lower CO2 emission and energy.
  • Primarily used in bridge decks, low slump concrete overlays.

5. Superplasticizers :

This admixture is used in gaining high slump value where the reinforcement is very close and the flow of the concrete is required for better workability or adequate vibration tools cannot be reached for consolidation. 
  • The major application to achieve high strength concrete.
  • Great slump loss and high workability are seen.

6. Shrinkage Reducing Admixtures :

Shrinkage Reducing Admixture is added to the mix which helps in reducing the early shrinkage and long term drying shrinkage.
  • This admixture helps in reducing the shrinkage.
  • In some cases, this admixture reduces the strength development of concrete.
There are other admixtures that are used to increase corrosion inhibiting property of concrete.
The other admixtures are used to resist the effect of the sulfur action and are used in water flow system, sewage, and drainage system where chemical action takes place. 

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