Polycarboxylate water-reducing agent is a high-performance water-reducing agent and a cement dispersant used in cement concrete. It can be divided into two categories chemically. The main chain is methacrylic acid and the side chain is carboxylic acid group. and, polyester type construction. We also need to understand the water-reducing mechanism. Next, we will introduce the water-reducing mechanism of polycarboxylate water-reducing agent.
Polycarboxylate superplasticizers are mostly anionic surfactants, which are mixed into cement and adsorbed on the surface of cement particles, and dissociate into organic anionic groups that are hydrophilic and lipophilic. Potential is usually used to characterize the dispersion effect. The greater the potential, the greater the electrostatic repulsion between cement particles and the more significant the dispersion effect. However, for polycarboxylate-based high-efficiency water-reducing agents, the potential is low (only ~ but mixed with The cement slurry also has excellent dispersion and low slump loss. This is because the polycarboxylate water-reducing agent is adsorbed on the cement layer in a comb shape. On the one hand, its spatial effect makes the particles disperse and reduces agglomeration. On the one hand, its long side chains can still stretch when the organic mineral phase is formed. Therefore, the polycarboxylate water-reducing agent is less affected by the hydration reaction of cement and can maintain excellent water-reducing and dispersing effects for a long time and reduce slump. Drop rate. In addition, different active groups are generally grafted onto the macromolecular chain, such as polyoxyethylene chains with a certain length, carboxyl groups, sulfonic acid groups, and polar groups that produce dispersion and flow effects on cement particles. , at the same time, the oxygen in the ether bond forms a strong hydrogen bond with the water molecules, and forms a hydrophilic three-dimensional protective film, which plays a certain role in the dispersion retention. Therefore, the static electricity in the polycarboxylate superplasticizer molecules The repulsion and the steric effect of the side chain make it have an excellent comprehensive effect []. The role of the active group makes the polycarboxylate water-reducing agent have a mechanism different from other high-efficiency water-reducing agents. It not only has excellent effects on cement particles Dispersion, and can maintain the fluidity of cement slurry with little loss over time.
After introducing so much, do you know more about polycarboxylate superplasticizer? The more you know about it, the better it will be for your use. There is no need to worry about this problem anymore. I hope these introductions can solve the mystery in your mind.
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Water reducing mechanism of polycarboxylate water reducing agent