Everyone knows that water-reducing admixture is a concrete admixture that can reduce mixing water consumption while maintaining the slump of concrete basically unchanged. Most of them are anionic surfactants, including lignin sulfonate, naphthalene sulfonate formaldehyde polymer, polycarboxylate water-reducing agent, etc. After being added to the concrete mixture, it has a dispersing effect on the cement particles, which can 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. So what types of water reducing agents are there?
1. Polycyclic aromatic sulfonate formaldehyde condensate. Polycyclic aromatic sulfonate formaldehyde condensates are available in MF.NNO, JN, FDN and UNF varieties. It is an anionic high-efficiency surface-active substance. It is a tan powder, easily soluble in water, and has water-reducing, early-strength, and reinforcing effects. It is a water-reducing agent with good performance.
2. The abbreviation of calcium lignosulfonate water-reducing agent: calcium lignosulfonate. It is a by-product of paper mills. It is a brown powder, non-toxic, non-flammable, and easily soluble in water. It can be used for ordinary Portland cement, slag cement and alumina cement. It can plasticize, entrain air, reduce water, and reduce moisture in concrete. It enhances and retards the setting effect, so the dosage should not be too much.
3. Melamine high-efficiency water-reducing agent. Melamine high-efficiency water-reducing agent is a water-soluble high-molecular polymer. Its main component is sulfonated melamine formaldehyde condensate. It is an anionic, early-strength, non-air-entraining high-efficiency water-reducing agent. The water reduction rate can reach 25%. . Representative products include Melment from Germany, NL-4000 from Japan, Peramin SMF from Sweden, and SM from China. According to statistics from German expert Professor Plank, naphthalene and melamine are currently the most widely used high-efficiency water reducing agents in the world.
4. Melamine high-efficiency water-reducing agent. Melamine-based high-efficiency water-reducing agents are low-air-entraining types and have no retarding effect. The water-reducing rate is equivalent to that of naphthalene-based high-efficiency water-reducing agents. It has a better effect on concrete reinforcement. However, the concrete collapses after adding traditional melamine water-reducing agents. Drop loss is also faster. Due to its colorless and low air entrainment characteristics, it is suitable for the production of dry mortar, colored pavement bricks and fair-faced concrete. In 2004, the China Academy of Building Materials Science successfully developed a new cost-effective melamine superplasticizer. Its modification technology route is unique. It uses melamine as the main raw material and activates its active functional groups through a hydroxymethylation reaction to generate hydroxymethyl. Melamine, and then introduce other prepolymerized monomers, increase monomers that may condense with melamine, change the molecular structure of the condensation product, and obtain a new melamine superplasticizer with better performance than traditional melamine superplasticizers.
5. The raw materials for the production of aliphatic high-efficiency water-reducing agents are sufficient and cheap, and the process is simple, so the synthesis cost is relatively low, and its water-reducing rate is high. Amine-based high-efficiency water-reducing admixtures are similar. This product promotes the early strength and later strength development of concrete; it has no crystallization in winter, no air entrainment, no chlorine salt, and no corrosion of steel bars; its adaptability to cement varieties is better than that of naphthalene series products, and it is suitable for prefabricated components Concrete production. This product has good compatibility with other admixture components and can be formulated into a series of products through compounding to achieve effects such as retarding, waterproofing, and antifreeze, and meet various requirements for commercial concrete.
6. Polycarboxylate Superplasticizer is a high-performance water-reducing agent and a cement dispersant used in cement concrete applications. Widely used in highways, bridges, dams, tunnels, high-rise buildings and other projects. Because the effective molecular structure is truly designed based on the action mechanism of dispersed cement, it is super-dispersed, which can prevent the slump loss of concrete without causing obvious retardation, exert a high plasticizing effect at low dosage, and maintain fluidity. Well, cement has a wide degree of freedom in adapting to a wide range of molecular structures, many synthetic technologies, and a lot of room for high performance. It has a significant reinforcing effect on concrete, can reduce concrete shrinkage, and has extremely low harmful substance content and other technical performance characteristics, giving concrete excellent Easy construction, good strength development, excellent durability, polycarboxylic acid-based high-performance water-reducing admixture have good comprehensive technical performance advantages and environmental protection characteristics, and meet the needs of modern concrete projects.
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