How does superplasticizers achieve its performance advantages in concrete materials?

How does superplasticizers achieve its performance advantages in concrete materials?

Keywords
Superplasticizer, high-range water reducer, polycarboxylate superplasticizer, mechanism of action, Chinese polycarboxylate powder supplier

The admixture that can significantly reduce the amount of mixing water under the condition of basically the same concrete slump is called high-efficiency water reducer. Under the condition of basically the same concrete slump, the admixture that can reduce the amount of mixing water by more than 15% is called high-efficiency water reducer.

High-efficiency water reducer has a strong dispersing effect on cement, which can greatly improve the fluidity of cement mixture and the slump of concrete, while significantly reducing the amount of water and significantly improving the workability of concrete. High-efficiency water reducer is mainly dispersed through electrostatic repulsion, steric hindrance, hydration film lubrication, and air entrainment isolation "ball" effect.

Electrostatic repulsion
The water-reducing agent molecule contains an appropriate amount of hydrophilic groups, such as sulfonic acid groups, hydroxyl groups, and ether bonds. Some polar groups extend in the water phase, and functional groups such as COO and SO3 will be ionized, forming a double electric layer structure on the surface of cement particles. The outermost layer of cement particles has the same charge. According to the mutual repulsion of the same charges, the concrete particles can be stably dispersed in the water, and the flocculation structure of cement particles disintegrates, thereby increasing the fluidity of the concrete.

Steric hindrance
The molecular shape of polycarboxylate superplasticizer is comb-shaped, with low-level fatty chains or ester groups on the side chains. These functional groups show non-polar properties. The anionic groups of the polymer are "anchored" on the surface of cement particles, and the side chains form a thick isolation layer, which plays a steric hindrance role and prevents the aggregation of cement particles.

Hydration film lubrication
The molecules of water reducers contain polar groups such as COO, SO3, and O. These polar groups can form hydrogen bonds with water molecules to improve the dispersibility of cement particles. After the active groups of the water reducer act on the active points of cement particles, a layer of solvent hydration film is formed to fully lubricate the cement particles.

Air entrainment and isolation "ball" effect
Whether it is sulfonate type or polycarboxylic acid type water reducer, the molecular structure contains hydrophilic groups and lipophilic groups. In essence, they are surfactants. Therefore, they can significantly reduce the tension of the liquid-gas interface, promote the formation of tiny bubbles, and make the concrete mixture have good fluidity. This effect is the air entrainment and isolation "ball" effect.