Superplasticizers are used in the concrete to achieve various goals like self-compaction, high slump concrete and high strength concrete. They reduce water content, and enhance workability.

Use of superplasticizers in concrete is the key to obtaining durable, strong and long lasting concrete. They are mainly used in concrete mixes that require a mix with both good flow and excellent early strengths.

Generally they can reduce the water to cement ratio by about 30%, thereby increasing the strength of concrete while maintaining its workability and without reducing the w/c ratio or any amount of cement content.

They can be classified into two groups, based on their chemistry and structure. One group consist of lignosulfonates and the other of polymers (PMS, PNS).

The use of plasticizers in concrete is mainly for improving the workability and reducing the water to cement ratio of the concrete. They also act as shrinkage reducing additives, which prevent the concrete from drying shrinkage during curing.

The effect of a superplasticizer on the setting time of flowing concrete depends mainly on the type and dosage of the admixture, as well as on the nature and amount of cement, humidity and temperature. In concrete containing small amounts of a superplasticizer the setting times are retarded, whereas at higher dosages they are accelerated.