Super Plasticizers and Retarders

super plasticizers are advanced water reducers that improve concrete workability, speed finishing, increase strength, conserve cement and help reduce shrinkage and thermal cracking. They are a key ingredient in many modern concrete mixes.

Superplasticizers are designed to transform stiff, low-slump concrete into flowing, pourable, easily placed concrete. They are also used to produce self-leveling concrete.

Flowing concrete is used for inaccessible places, floors and where quick placing is required. It is strong and can withstand high loads. It has a very low water/cement ratio (0.2 or less) and the strength can be up to 120 MPa.

The use of a flow concrete is very useful in constructing bridges, tunnels, roads and foundations. It is also used in construction of sewage treatment plants.

Retarders are used in regular intervals to overcome slump problem while placement of concrete. These retarders can be used in conjunction with a super plasticizer to maintain proper slump during the placement of the concrete.

Some super plasticizers can create a problem while finishing the concrete. They are very sticky and tend to drag the trowel across the surface of the concrete. To avoid this, the finisher can use coarser fine aggregates or delay finishing until the concrete sets.

Viscosity Modifying Admixtures are a family of admixtures that perform the opposite of super plasticizers by reducing the concrete's slump and helping prevent segregation in aggregate-based mixes. They do this by increasing the adsorption of a PCE (polycarboxylate ester) to the cement paste.