Plasticizers are chemicals with unique physico-chemical properties designed to reduce the amount of batched water without changing the consistency of the mix (plaster, concrete).
Using plasticizers as a concrete admixture improves the rheological parameters of the mixture. In addition, reduced amount of water increases the durability of the finished products, and improves strength parameters of concrete.
Molecules of plasticizers are adsorbed on the surface of the joint particles. As a result, agglomerates are separated and dispersed in the mixture volume. This process takes place according to the lubricating, electrostatic or steric mechanism. The type of operational mechanism of plasticizers, depends on their chemical structure.
electrostatic mechanism – it is based on the adsorption of negatively charged molecules on the surface of cement grains, and electrostatic repulsion of unipolar charges, resulting in the breakdown of cement agglomerates and liquefaction of the mix.
steric mechanism – it is based on the adsorption of plasticizers having a comb structure on the surface of cement particles and formation of obstacles that prevent grains to connect with one another to form agglomerates. This is the most effective way to liquefy the mix.
lubricating mechanism – involves formation of a lubricant layer, i.e. adsorption of plasticizer molecules onto the surface of cement grains, reducing friction between the particles. This increases slippage between the grains, improving the consistency of the mix.
