Polycarboxylic acid superplasticizer is a new type developed in recent years at home and abroad. It has a “fluid” structure and consists of a main chain with free carboxylic anion groups and a polyoxyethylene side chain. It can be used to change the monomer The types, proportions and reaction conditions can produce various high-performance water reducing admixtures with different properties and characteristics. The introduction of different functional groups by molecular design can produce early-strength, standard and slow-setting high-performance water reducers. It has a higher water reducing rate, better slump retention performance, smaller drying shrinkage, and a water reducing agent with certain air-entraining properties.
Main Technical Characteristics of Polycarboxylic Acid Superplasticizer
- The polycarboxylate superplasticizer has a low content and a high water reducing rate. The content of polycarboxylic acid superplasticizer accounts for 0.80%-1.25% of the cementitious material, and its water reduction rate can reach (20-35)%. It is used in conjunction with fly ash to make the water glue relatively low, so It can be used to prepare medium and high-strength high-performance concrete.
- The concrete has high fluidity and low slump loss. Due to the good dispersion stability of the polycarboxylic acid superplasticizer, the high-fluidity concrete (slump ≥180mm) prepared by it has little loss, basically no slump loss in one hour, and slump loss in two hours can be less than 15%. Used in conjunction with fly ash, its small content can obtain excellent fluidity, which is suitable for the process requirements of producing commercial concrete, especially for pumped concrete, which is not prone to pipe blockage.
- Good adaptability to cementitious materials. In engineering practice, the cement produced by different manufacturers is mixed with a large amount of fly ash and mixed with a large amount of fly ash, and it has good compatibility with different cements without obvious bleeding segregation. , The phenomenon that hinders the growth of concrete strength occurs, and because of its high water reduction rate, it is suitable for use with fly ash, which reduces the shrinkage of fly ash concrete, and significantly improves the pumpability of concrete, and improves the concrete Durability. When the concrete design strength grade is the same, the amount of cement increases, the amount of water-reducing agent increases with a small amount, the water-binder ratio decreases, and the strength of concrete increases; for concrete of different design strength grades, the amount of water-reducing agent increases slightly as the amount of cementing material increases, The water-binder ratio decreases, and the strength of the concrete increases, but the workability of the concrete remains stable overall, and the slump can reach (180-240) mm.
- It is suitable for pouring waterproof and impermeable concrete, and has low requirements for construction environment temperature. The polycarboxylate superplasticizer is used to formulate commercial concrete for pumping. Due to the high fluidity of the concrete, it is easy to be poured and compacted. In addition, the polymer has the polymerization activity of the hydration product to form a gelled hydrate to fill the voids, and the concrete compactness, The strength is greatly improved, the filling effect of the polymer and the sealing effect of the polymer film improve the impermeability and crack resistance of the concrete; and the content of fly ash is large, the heat of hydration of the concrete is small, and the plastic preservation function of the water reducer is obvious It is suitable for large-volume concrete and summer construction. For winter construction, because the water glue is relatively low, the spatial flexible network formed by the polymer improves the cohesion of the concrete mixture and enhances the early anti-freezing performance of the concrete.