Admixtures II Function of Admixture

 Admixture : 

Admixture are the materials added to the basis constituents (cement, water and aggregate ). Just before or during mixing in order to modify the properties of concrete and obtain concrete with desired performance."

Functions : We add admixtures as to obtained concrete of required performance to be used for following purposes :

(1) Workability : To obtained concrete of high workability.

(2) Strength and Durability : Admixtures increases the strength of  concrete and make them more durable by reducing the  water content and by densification of concrete.

(3) Hydration :  They also play an important role inn changing the rate of hydration of cement.

(4) Setting Time : It change the setting by retarding of accelerating initial setting time.

(5) Segregation and Bleeding : By reducing water content for a given workability, admixture can also reduced segregation and bleeding of concrete mix.

(6) Pumpability :  Admixture increases the flowability of concrete making it easy to pump.

(7) Impermeable : Admixture reduces the  permeability of liquids through concrete thus making water tight concrete.

(8) Corrosion : It  inhibit the  corrosion of reinforcement  in concrete.

(9) Heat of hydration : It reduces the development of heat of hydration which is useful in mass concreting operations.

(10) Bond : Admixtures help to increase the bond between steel and concrete and also bond between old and new concrete surfaces.

(11) Weight : It helps to decreases the weight of concrete per cubic meter.

(12) Strength at early ages : It accelerate the rate of  development of  strength at early ages.

(13) Cellular concrete :  Admixture are useful for as it helps to produce cellular concrete.

(14) Resistance to freezing : Admixtures increase the resistance of concrete to freezing and thawing.

(15) Germicidal use : It help to produce concrete of germicidal and insecticidal properties.

(16) Resistance to chemical : Admixtures helps concrete to resist chemical attacks.

(17) Coloured concrete : They also procedure coloured concrete.