Polycarboxylate superplasticizer is a kind of unsaturated monomer containing carboxyl group, which is copolymerized with unsaturated monomer containing other functional groups, which can make concrete have excellent performance in water reduction, collapse protection, environmental protection, etc.
High polymer. The advantages of low dosage, high water reducing rate, controllable substructure, good dispersibility, green environmental protection, and strong adaptability of polycarboxylate high-performance superplasticizer have attracted the attention and research of scholars and experts.
It is widely used in engineering construction in various fields, thus becoming the future development trend of concrete admixtures. The research of polycarboxylate high-performance water reducing agent is an inevitable requirement in the field of concrete.
Polycarboxylate superplasticizer contains hydrophilic groups (such as carboxyl, sulfonic acid and other anionic groups) and hydrophobic groups (such as alkyl) in the molecule, and is an anionic surfactant.
When the polycarboxylate superplasticizer Chemicalbook is added to the cement paste, a coexistence system of cement, water and polycarboxylate superplasticizer is formed, so that the cement particles can be dispersed, and the macroscopic performance is that the cement paste has a certain dispersion performance.
In the cement slurry, the dispersion mechanism of polycarboxylate superplasticizer is generally believed to be the main role of steric hindrance and the secondary role of electrostatic repulsion.
In addition, the complexation of calcium ions and the lubrication of hydration film also play a role. to a certain important role.
The theory of steric hindrance When the molecules of the polycarboxylate superplasticizer first come into contact with the cement particles, the negatively charged main chain in the molecules of the polycarboxylate superplasticizer can be adsorbed on the surface of the positively charged cement particles, that is, the phenomenon of “anchoring” occurs. , and the long side chains in the polycarboxylate superplasticizer molecules are extended in the liquid phase of the cement slurry to form an adsorption layer with a chemical thickness of a certain thickness, and can be simultaneously extended with other polycarboxylic acids in the liquid phase of the cement paste.
The long side chain of the water reducing agent molecule forms a three-dimensional and crossed conformation. When the cement particles move toward each other, the adsorption layer overlaps, and the larger the overlapping range, the greater the repulsive force between the cement particles, thereby improving the dispersibility of the cement particles.
Relevant studies have shown that the thicker the molecular adsorption layer of the polycarboxylate superplasticizer formed on the surface of the cement particles, the more favorable it is to improve the dispersibility of the cement particles. Therefore, steric hindrance plays an important role in the dispersion mechanism of polycarboxylate superplasticizers.
High water reduction rate: the water reduction rate can reach more than 25%, and the fluidity can be greatly improved under the condition of the same amount of water added to the concrete;
High slump retention: The traditional polycarboxylate powder water reducer will cause certain damage to more or less carboxylic acid groups due to the high temperature in the spray drying process.
Thereby, the slump retention performance after the liquid is converted into a solid is greatly reduced. It is manufactured by a special process, so that the carboxylic acid group is not destroyed during the powder manufacturing process, so that the slump retention of the original liquid mother liquor is retained.
Good solubility and fast dissolution rate: due to its uniform particle size and large specific surface area. Therefore, it can be dissolved quickly in the process of water dissolution. And there is no obvious impurities after dissolution.
PCE is a game-changer in concrete technology and has demonstrated exceptional ability to increase the strength and durability of concrete.
Today, we’re delving into the world of polycarboxylate water reducers – a revolutionary material that is changing the way buildings are constructed.
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