Concrete production is based on a chemical reaction that binds water with cement and fine aggregates (sand, gravel) to transform them into concrete’s final form. The resulting concrete is strong and durable, but it can be expensive to produce.
Some concrete producers have found that reducing the amount of water in a concrete mix can result in stronger, more durable concrete. This is called “water reduction.”
The addition of water-reducing admixtures, such as superplasticizers, can reduce the water content of concrete without compromising workability or durability. This is because these admixtures improve flow, permeability and workability by increasing the dispersion of fine aggregates or cement.
SMF-, SNF- and MLS-based superplasticizers are able to achieve these results because they dissolve in the hydration solution, creating an ionic group that bonds with the cement particles. During the curing process these molecules release their charge, dispersing the cement grains and improving the strength and durability of concrete.
Superplasticizers can be used to make a number of different types of concrete, including self-leveling, low-permeability, high-strength, pumpable and lightweight concrete. They can also be used to make concrete from materials that are difficult or expensive to procure, such as slag or fly ash.
The optimum dosage of superplasticizer depends on the type of cement, the water-cement ratio and the type of admixture. Generally, the optimum dosage is given in the manufacturer’s instructions.