Research and Development Status of Polycarboxylate Superplasticizers at Home and Abroad

High-efficiency water reducer was first invented and used by Japanese people. In addition, other economically developed countries are also at the forefront of the world in the development of high-efficiency water reducers. Due to the unbalanced development of concrete technology in China, performance and cost issues have affected the development of polycarboxylate superplasticizers. At present, the research on polycarboxylate superplasticizer in China is still in its infancy, and the synthesis method of polycarboxylate superplasticizer is continuously explored through molecular design. Many units have achieved some better.

Scientific research results. From the related papers of domestic journals and journals, there are many basic researches and experimental literatures on molecular structure and mechanism, synthesis and characterization, esterification kinetics and performance evaluation of polycarboxylate superplasticizers. However, the literature on new products and practical construction applications is less, and compared with foreign process technology, the domestic synthesis process is still not innovative enough, and the product varieties are still too few, although many research institutes or manufacturers are working on process improvement. However, based on the molecular design principle, the synthesis process of graft copolymerization using maleic anhydride, methacrylic acid, acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) as raw materials is generally equivalent, and the products are generally reduced. The problem of insufficient dispersion of the water agent。The role of concrete superplasticizers, whether it is ordinary water reducer or superplasticizer, their addition in concrete and cement products effectively improve the workability and mechanical properties of the mixture during the construction of the mixture. By dispersing the cement in the cement slurry into fine particles, the water cannot be wrapped by the cement, and the water is used as the dispersed cement to the greatest extent, which reduces the viscosity of the mixture, thereby greatly improving the workability of the cement mixture, and thus Conducive to mechanized construction and labor intensity, and reduce the impact of human factors on the quality of the project. The amount of water is reduced while ensuring the same workability, thereby reducing the amount of water that does not participate in cement hydration.Studies have shown that the properties of hardened concrete and cement products are directly related to their microstructure. Usually the amount of water used for mixing is far beyond the water requirement of the hydration of the cementitious material. During the hardening process of the slurry, this part of free water evaporates continuously, and finally the hardened product It leaves irregularly shaped pores that are structural defects for concrete and cement products. Therefore, the addition of water reducing agent reduces the amount and dispersion state of free water, and reduces the probability of structural defects. The products using water reducing agent in engineering have the same age strength as ordinary concrete and cement products. Significantly improved. In addition, the design strength requirement can be achieved by using low-grade cement. When the strength meets the design requirements and the workability is constant, the addition of water-reducing agent can save the cement dosage. Generally, the high-efficiency water reducing agent can save cement by 20%~30%. The amount of cement is directly related to the strength of the concrete. For hardened concrete, the aggregate relies on the cementitious material as the binder. The strength of the hardened concrete depends on the weak layer of its structure. The strength of the aggregate itself is often higher than the strength of the concrete, aggregate and bone. The bond strength of the material plays a decisive role in the strength of the concrete.If the amount of cement is large, the possibility of defects between the aggregates will increase, so the method of increasing the strength of the concrete is to reduce the amount of cement under the premise of satisfying workability. In addition, the production of cement consumes a huge amount of energy, and the material for producing cement is a non-renewable resource. Therefore, the so-called water-reducing agent industry is called "Chaoyang Industry". The dispersion of the water reducing agent on the cement slurry changes the pore structure, and the other properties of the concrete also change. At present, the most widely used in commercial concrete is the high efficiency air entraining water reducing agent, which reduces the water consumption under the same working conditions; changes the existence state of free water under the same water consumption conditions, and makes the freedom The water is dispersed in the concrete mixture in the form of a large number of tiny bubbles, which improves the fluidity of the mixture; in addition, the defects left by the free water are eliminated in the hardened slurry, and the uniformly distributed pores reduce the weight of the component and improve The durability of concrete has a certain influence on concrete shrinkage and creep. Reduce work intensity and increase construction speed. More and more projects use commercial concrete and pumped concrete. Mechanized construction can ensure the stability of construction and quality, and the production of commercial concrete reduces noise pollution and dust pollution, improves the working environment of workers and reduces labor intensity. For developers, it reduces construction costs, the use of water reducing agents, and expands the use of concrete, especially for the production of high-strength, high-performance concrete and high-flow self-compacting coagulation.