Different Types Of Admixture for Concrete

Admixtures are mixed with the concrete for reducing water content, mitigating the setting property, making concrete light, and also modifying concrete properties. Admixtures are added right before or during the mixing of concrete. Excessive amount of water may cause extra bleeding and separation. That is why admixtures are added to the concrete to prevent all of this problem. Many types of admixtures provide the combination of plasticizer, superplasticizer and air entrainers.

Basically, there are two type of admixtures available. One is natural admixtures and another is chemical admixtures. Natural admixtures are rice husk, flour, egg mix, ghee and the chemical admixtures is GGBS, fly ash, pozzolana.

In previous time, natural admixtures were used widely but this was very expensive and not much modification was not possible in that time. On the other hand, usage of chemical admixture provides variety in the construction industry.

Types of Chemical Admixtures

1. Plasticizers

2. Superplasticizers

3. Accelerators

4. Retarders

5. Air entrainers

Plasticizers

This are used for improving the plasticity of fresh concrete to reduce water content. Workability and water cement ratio do not affect because of using plasticizer. There are few types of plasticizer available like calcium, sodium, ammonium, lignosulphonates, polyglycol esters. These are added 0.1% to 0.4% ratio.

After adding this element is absorbed on the cement particles. This element also creates expulsive force named zeta potential. This expulsive force depends upon the used amount of plasticizer.