my country's concrete additives started late. In 1950, the North China Kiln Industry Company Research Institute produced my country's first additive product, the Great Wall brand air-entraining agent. This product was first used on the runway of Tianjin Airport to improve the frost resistance and corrosion resistance of concrete, and was also used in the Wuhan Yangtze River Bridge and other water conservancy projects. In the next two decades, the development of admixtures in my country was still very slow. Except for other units that used pulp waste liquid to produce low-grade plasticizers, most projects did not use water-reducing agents, that is, antifreeze for winter construction. They are also made of chlorine salt as the main material.
It was not until 1973 that the development and production of high-efficiency water-reducing admixtures was promoted in my country due to the influence of international construction technology and new concrete technology. Since the diffusion agent in the dye industry was successfully transplanted into the ranks of concrete water-reducing agents, it has since affected the rapid development of water-reducing agents produced from various fractions of coal char, especially naphthalene and its homologues, as the main raw materials. From 1974 to 1976, the National Institute of Building Materials developed two high-efficiency water-reducing agents, MF and Jian 1, which used methylnaphthalene and naphthalene residual oil as the main raw materials. Tsinghua University developed NF superplasticizer using naphthalene as raw material, Tianjin Building Materials Institute developed UNF, and Wuhan Metallurgical Construction developed FDN. In view of the lack of naphthalene raw materials, the Building Materials Institute developed AF superplasticizer using anthracene oil as raw material.
The Second Bureau of Transportation and Communications has developed CRS using coumaron resin as raw material. At the same time, ordinary water reducing agents have also made great progress. In 1975, Jilin Kaishantun Chemical Fiber Factory developed calcium lignosulfonate, and Guangdong Chemical Factory also produced similar products. The widespread production of ordinary water-reducing agents and high-efficiency water-reducing agents has led to the emergence of composite admixtures. Composite admixtures have a broader market background for changing concrete properties. The different technical requirements of various types of projects give composite manufacturers a lot to do. According to incomplete statistics, in the fourteen years from 1973 to 1987, my country's admixture factories have grown from few to more than 150, of which more than 80% are composite manufacturers. The variety of admixtures has also grown from a few to more than 16 to more than 300 brands, which indicates that my country's admixture industry has begun to take shape and mature.
In order to further strengthen technical management and regulate the market, in 1987, my country promulgated its own "Concrete Admixture Standard" (GB8076-87) for the first time; at the same time, it also promulgated There are "Classification, Determination and Definition of Concrete Admixtures" (GB8075-87); "Test Methods for Homogeneity of Concrete Admixtures" (GB8077-87). These three standards respectively make specific provisions on the types, technical indicators and inspection methods of concrete admixtures: now GB8076-87 has been replaced by GB8076-97. In the following years, our country has successively promulgated the "Technical Specifications for the Application of Concrete Admixtures" (GBJ119-88); "Concrete Antifreeze Standards" (JC472-92); "Concrete Pumping Agent Standards" (JC473-92) ; "Concrete Expansion Agent" (JC476-98) and other series of admixture standards, these standards are what we must be familiar with when applying admixtures.
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