Water reducing agent is a concrete admixture that could reduce the quantity of mixing water beneath the condition that the slump of the concrete is simply unchanged. To be able to improve and adjust the function of concrete or mortar, organic, inorganic or composite compounds are often added during mixing. After adding the concrete mixture, it includes a dispersing impact on the cement particles, that may improve its workability, reduce the unit water consumption, and improve the fluidity of the concrete mixture. Or reduce the unit cement consumption and save cement.
Probably the most commonly used water reducers are lignosulfonates and their derivatives, higher polyols and polyol complexes, hydroxycarboxylic acids and their salts, polyvinyl ethers and their derivatives, etc.
Superplasticizers mainly include, naphthalene sulfonate formaldehyde condensate, polycyclic aromatic hydrocarbon sulfonate formaldehyde polycondensate, sulfamate, melamine sulfonate formaldehyde polycondensate, etc.
High-performance water-reducing agents are mainly polycarboxylic acid-based water-reducing agents.
Lignosulfonate. It is a common water reducing agent. Its raw material is lignin, which is generally extracted from coniferous trees. Lignin is polymerized from three lignin monomers: p-genol, coniferyl alcohol and sinapyl alcohol. It is employed for mortar. It could improve workability, fluidity and strength, and the water reduction rate is 5%-10%.
Naphthalene sulfonate water reducer. It is a high-efficiency water reducer that individuals used earlier. It is the item of sulfonation of naphthalene by sulfuric acid and condensation with formaldehyde. It can be an anionic surfactant. The looks of this type of water-reducing agent may be light yellow to brownish powder depending on the product, easily soluble in water, and includes a good dispersing impact on many powder materials such as cement, with a water reduction rate of 25%.
Melamine water reducing agent. It is the item of sulfonation of melamine by sulfuric acid and condensation with formaldehyde, so the chemical name is sulfonated melamine formaldehyde resin, which belongs to anionic surfactants. The looks of this type of water reducing agent is white powder, which is easily soluble in water, has good dispersion to powder materials, has high water reduction rate, and has good fluidity and self-repairing properties.
Powder polycarboxylate. It is a new kind of high-performance water-reducing agent developed in recent years. It has excellent water-reducing rate, fluidity and permeability. It obviously enhances the strength of cement mortar, however the production process is complicated and the price is generally higher.
Casein. It is a biopolymer obtained by precipitation of milk with acid and cylinder drying.
Polycarboxylic acid-based high-performance water reducer. Polycarboxylic acid-based high-performance water-reducing admixture is a kind of concrete superplasticizer with advanced technology content, good application prospect and excellent comprehensive performance in the world.
At present, the polycarboxylate superplasticizer is trusted, which really is a compound product of carboxylate graft copolymer and other effective additives. The performance comparison with other similar products suggests that the polycarboxylate series high-performance water reducing agent has reached the advanced degree of today's society when it comes to technical performance indicators and cost performance. Polycarboxylate superplasticizers are mainly used to formulate low-water-cement ratio, high-strength, self-compacting and high-durability concrete. It is the key development direction of concrete good performance water reducer.