Concrete is a building material with high demand and wide application coverage. The application of concrete admixtures improves the performance of concrete. It can increase the construction speed and quality of construction, improve the production process and employee standards, and save concrete and electricity energy. After entering the 1970s and 1980s, with the increasing development trend of concrete and technical problems of concrete pouring, concrete admixtures have attracted people's attention.
Many industrialized production capitalist societies use admixtures in all or most of their concrete. Therefore, admixtures have become the fifth component of concrete in addition to concrete sand, stone and water. Our country started producing, processing and applying admixtures at about the same time as Japan. Starting from the early 1950s, air-entraining agents based on rosin thermopolymers were mainly produced to meet the needs of water conservancy projects and port infrastructure projects, as well as to improve concrete cohesion and improve concrete resistance. Admixture based on the pressure strength of sulfite pulp sewage core. The period from 1960 to 1970 was a low ebb period. During this period, products developed accelerating setting agents and plasticizers based on calcium sugar. The period from 1970 to 1980 was a period of ups and downs in the development trend of admixtures. Various provinces and enterprises in China have successively developed and identified naphthalene sulfonate-decorated formaldehyde condensation reactants, β-naphthalene sulfonate, alicyclic epoxy resin glue, sulfonate, etc. There are 20 kinds of high-efficiency water-reducing admixtures as main components such as sulfamate, sodium thiocyanate and formaldehyde condensation reaction products. There are nearly 10 kinds of common admixtures with lignosulfonate and humate as important components. There are 10 kinds of composite early-strengthening admixtures with lignin and sulfate, naphthalene sulfonate and sulfate, sugar calcium and sulfate, polycyclic aromatic hydrocarbons and sulfate as main components. In addition, there are retarder admixtures composed mainly of molasses, calcium saccharide, and lignocellulose naphthalene sulfonate, as well as air-entraining admixtures composed of sodium rosinate, chemical and inorganic salts.
Our country has a vast territory, many types of concrete, and various standards for using admixtures. Therefore, it is essential to develop intelligent admixtures. For example, early-strength admixture S type and UNF-3 admixture can take into account the requirements of winter construction measures in warm temperate areas. Manufacturers include Wuxian Phosphate Fertilizer Factory, Tianjin Ziji Production Factory, etc., such as super early-strength admixture, early-strength air entrainment Admixtures, etc. At present, there are about 100 types of admixtures in our country and more than 80 manufacturers.
According to statistics, the current total annual output of concrete admixtures in my country is about 220,000 tons, of which calcium lignosulfonate is the core, and sodium lignosulfonate, magnesium lignosus, and humic acid phosphate are usually added according to local conditions. The total output of admixtures is 27,000 tons, accounting for 12.5% of the total output of admixtures. Focusing on sulfonated coal tar products, the total output of melamine formaldehyde resin and sulfonated coumaron resin is 30,000 tons of high-efficiency water reducing agents, accounting for 13.7% of the total output of admixtures. The total output of early strength additives with sodium sulfate as an important component is 100,000 tons, accounting for 43% of the total output of admixtures. The total output of retarder and retarder admixture produced and processed by neutralizing molasses with quicklime powder is only 6,000 tons. The total annual output of air-entraining agents and air-entraining admixtures produced and processed with rosin soap stock core is even smaller, only a few hundred tons. The total annual output of anti-refrigerants with calcium chloride, sodium oxide and sodium nitrite as important components is 15,000 tons, accounting for 7% of the total output of admixtures. The total annual output of accelerators, with alunite expansion agent as the core product, is 22,000 tons, accounting for 10% of the total output of admixtures. The quantity, total output and composition ratio of various admixture types are shown in Table 1. According to the needs of social and economic trends, based on the amount of available admixture concrete of 50 million tons, the scale of my country's concrete admixture enterprises is expected to exceed 280,000 tons. </p
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