Superplasticizers, also known as high range water reducers, are chemical admixtures used where well-dispersed particle suspension is required.These polymers are used as dispersants to avoid particle segregation (gravel,coarse and fine sands),and to improve the flow features (rheology) of suspensions such as in concrete applications. Their addition to concrete or mortar allows the reduction of the water to cement ratio without negatively affecting the workability of the mixture, and enables the production of self-consolidating concrete and high performance concrete. This effect drastically improves the performance of the hardening fresh paste. The strength of concrete increases when the water to cement ratio decreases.
There two main superplasticizers,naphthalene based superplasticizer and polycarboxylate based superplasticizer,are used in concrete nowdays.
Naphthalene based superplasticizers are mainly formulated from naphthalene sulfonate formaldehyde sodium salts and polycarboxylate based superplasticizer is formulated from polycarboxylate ether.