We generally use chemical admixtures in preparation of concrete along with aggregates and water to modify certain properties of concrete like to increase workability, reduce shrinkage and corrosion, to entrain small air bubbles in the structure, accelerating or retarding hardening process and many more. The addition of these admixtures in small quantities not only alter different properties but also make construction more economical.
Plasticizers are the admixtures which are primarily used to increase workability of concrete along with decreasing water to cement ratio thus increasing strength of the concrete. For example adding certain deflocculating reagents like lignosulphate, polyglycol ester, carbohydrates (dose 0.1-0.4% by weight) reduces water to cement ratio by almost 5-15% along with increasing slump value by 30–150 mm.
There are certain modified chemicals which are considered in another category of admixtures called superplasticizers like modified lignosulphates, sulphonated napthalene formaldehyde which causes reduction in water to cement ratio by almost 30%.