Polycarboxylic superplasticizer

The first is the diversity and adjustability of the molecular structure, and the second is to concentrate and improve the advantages of the high range superplasticizer, and realize the green and pollution-free production process.

In terms of the mechanism of action, the molecular structure of the polycarboxylate superplasticizer is comb-shaped, the polar anion "anchoring" group with a strong backbone is used to adsorb on the cement particles, and the outward extension of the comb structure supported by many branched chains provides a sufficient spatial arrangement effect for the further dispersion of cement particles. Compared with the electric bilayer electrical repulsion of naphthalene-based superplasticizer, steric hindrance makes the dispersion hold for a much longer time.

By appropriately changing the comb structure of the polycarboxylate superplasticizer and changing the density and length of the side chain appropriately, the high-water-reducing and high-early-strength superplasticizer suitable for prefabricated components can be obtained.

The polycarboxylate superplasticizer has low dosage, high water reduction rate and good slump, but the following problems also occur in the application:

(1) The dosage is very sensitive when the water-cement ratio is small, and shows a higher water reduction rate, while when the water-cement ratio is big (more than 0.4), the water reduction rate and its changes are not so obvious, which may be related to the mechanism of action of the polycarboxylate superplasticizer, its dispersion and retention role lies in the steric hindrance effect of the formation of the molecular structure, and there is enough water molecule spacing effect in the cement dispersion system when the water-cement ratio is big, so the steric hindrance of polycarboxylate molecules is naturally smaller.

(2) The effect of dosage is more obvious when the amount of cementitious material is large. Under the same conditions, when the total amount of cementitious material < 300kg/m3, the water reduction effect is less than that of >400kg/m3, and when the water-cement ratio is large, the amount of cemented material will have a superimposed effect.

Polycarboxylate superplasticizer is developed for high-performance concrete, so its performance and price are more suitable for high-performance concrete.