Concrete admixtures are used to modify the properties of fresh and hardened concrete to get desired ones.

1. CONCRETE ADMIXTURES AND
THEIR USES
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2. Concrete Admixtures or additives are product that are added to
concrete while mixing to achieve desired properties as we want.
In short they modify properties of concrete by means of physical
or chemical actions

3. 1 Plasticizers
2 Superplasticizers
3 Set retarders
4 Set accelerators
5 Air entraining admixtures
6 Pozzolanic or Mineral admixtures
7 Damp-proofing and water proofing admixtures

4. 1) Plasticizers
They are used to improve workability of concrete. They are also
known as water reducers.
Plasticizers are also used to reduce water/cement ratio.
Examples of plasticizers
- Lignosulphonates and their modifications and derivatives
- Polyglycol esters, acid of hydroxylated carboxylic acids
- Other products such as carbohydrates
- Benzoates

5. 2) Superplasticizers
Superplasticizers are high range water reducers of advance technology.
Following are a few polymers which are commonly used as base for
superplasticizers.
- Cross linked advance polymers
- Acrylic polymer base
- Modified lignosulphonates

6. 3) Set retarders
Set retarders are used to decelerate the setting process of concrete.
They have found bigger application in Ready Mix
Concrete in which initial setting time of concrete has to be extended up to
few hours.

7. 4) Set accelerators
They are as name implies used to reduce the setting time of concrete.
They allow us to early removal of the formwork. So that it is obvious that it
could be used as emergency repair work.

8. 5)Air-entraining admixtures
Air entraining admixtures are used to improve workability of concrete and
Making is resistant to freezing and thawing action of weather.
Air entraining admixtures are made up of either of following material
- Aluminium powder
- Natural wood resins
- Animal and vegetable oils and fats.
etc.

9. 6)Pozzolanic or Mineral admixtures
Fly-ash, Surkhi, Bajri, Rice husk ash are commonly used pozzolanic admixtures.
Pozzolanic admixtures like fly ash do not directly contribute to strength but
improves durability and reduces cost as well as permeability.
The major benefit of use of pozzolanic admixtures is reduction in cost of
concrete.

10. 7)Damp proofing and water proofing admixtures
Heavy mineral oil free from fatty acid and vegetable oil has been proved to be
effective in rendering concrete waterproof.