Concrete Superplasticizer

concrete superplasticizer is an important admixture used in the production of high-performance concrete. It helps to improve the workability and strength of high-performance concrete in conjunction with silica fume, fly ash, slag, or other additions.

Superplasticizers (SP) are soluble macromolecules, hundreds of times larger than water molecules. They adsorb to the C3A in cement particles and release entrapped water.

In a concrete mix, these superplasticizers are added at a low dosage with a maximum of 2 per cent of the total water. The mixture is then mixed at a minimum of 3 minutes with a mechanical drill or 5 minutes with a mortar mixer.

The addition of superplasticizers reduces the amount of water in concrete mixes without reducing the strength or workability of the mix. This can save a lot of money on construction materials as well as time.

It also helps to prevent segregation in aggregate-based mixes.

A common problem with using superplasticizers is that they tend to lose their workability quickly. This may cause difficulties when placing concrete as ready-mixed delivery trucks must be able to make long trips between job sites.

These problems can be addressed by using the opposite of a high range water reducer: viscosity modifying admixtures (VMA). VMAs are powdered admixtures that reduce the slump of concrete and help to prevent segregation in aggregate-based concrete.

The strength of high-performance concretes containing SMF and SNF-type superplasticizers is higher than that of reference concrete made at the same slump with no admixture, even if the water:cement ratio is equal. However, the enhancement of strength is mainly attributable to the reduction in water content caused by the use of these admixtures.