9.3 : מעכבי מים (פלסטיזרים)

Consider concreting in locations that are difficult to access in a mold. Plasticizers help concrete compact on its own, enhancing workability with less water or cement.

Common plasticizers include lignosulfonic acids and hydroxylated carboxylic acids, functioning as water-reducing admixtures that can cut water use by 5 to 15 percent in concrete.

The surface-active agents in plasticizers alter the interfacial forces between non-mixing phases and adhere to cement particles, imparting a negative charge, fostering repulsion, and stabilizing their dispersion while repelling air bubbles.

The negative charge induces a layer of aligned water molecules around each particle, effectively distancing them.

Lastly, particle movement is enhanced, and water is liberated from the clustered system, making it available to ease the mix and improve workability.

Plasticizers enhance the dispersal of cement particles, increasing the surface area for hydration. This dispersion boosts early-age strength relative to mixes without admixtures.

These admixtures' impact on strength is more pronounced in cements with low tricalcium aluminate or low alkali levels.

Before using plasticizers in construction, testing is essential to identify issues like segregation, bleeding, or reduced workability.