Concrete is the amount of large, wide application of materials, application of concrete admixture of concrete is the main way of technological progress , which can improve the speed and construction quality , process improvement and working conditions, cement and energy saving . After entering the 1960s , with the growing needs of concrete and construction technology of concrete, concrete admixtures has increasingly attracted peoples attention. Many industrialized countries for use in all or most concrete admixtures , the Nordic countries 100% admixture of cement mixed with cement accounts for the amount of 100% Japan , West Germany, the Soviet Union has reached more than 50 %, U.S. 65 %. Therefore, it has become the fifth ingredients except the cement sand, stone and water constitute concrete.
Concrete admixtures is worth mentioning that all these years particularly striking superplasticizer, which promotes the development of high- strength concrete, improves the workability of concrete, so pumping height of 432 meters , achieved for several high speed and efficient construction ten hours , hundreds of thousands of cubic meters of large volumes of modern concrete by the use of high mobility can be achieved without vibration, no noise and efficient civil construction . Due to a significant reduction in concrete mixing water , but also for high flow , high strength and durability of high-quality concrete, thus making the rapid development of concrete technology .
A foreign overview of the development of concrete admixtures and Features
As early as the 1930s had foreign development and application note admixture . British EWScripture 1935 successfully developed lignin sulfonate as the main ingredient , " Psou in " (POZZOlith) water reducer . In the early 1950s from the United States , Japan superplasticizer technology , Kao Corporation developed β- naphthalene sulfonate formaldehyde condensate as the main ingredient , " Maye too " (Mighth) water reducer . 1964 West Germany developed an alternative to melamine-formaldehyde condensates as the main ingredient , " Meier Ming " (Meiment) superplasticizer . In 1974 , Japan imported from West Germany this superplasticizer tradename NL-4000. This results in the use of three different components of the most water-reducing agent present in the world . In addition , there are classes molasses , glucose, etc. Other types of additives . In 1979 the London market on more than 100 kinds of admixtures , the Japanese market admixtures have 205 kinds in 1982 , is currently the worlds admixtures number has more than 300 species.
Development characteristics of countries, mostly combined with their own resources , the use of wastes and industrial by-products such as pulp waste , coal tar and water reducing sugar residue research . Emphasis on the development of quality standards and application specifications , development and use of complex admixtures , such as water reducer, retarder, coagulant , aerated agent , early strength agent compound used to meet the requirements of different uses. Emphasis on applied research admixtures on applied research, mostly from the water reducing production company , organization or financing , production plants not only sell products , but also provides the use of equipment, technical service door .
Second, Chinas current situation and forecast production of concrete admixtures
China began production and application of water reducing time and Japan are similar. Starting from the beginning of the liberation of the 1950s , was mainly to meet the hydraulic , port workers building needs heat produced polymer with rosin -based air-entraining agents , as well as to improve the workability of concrete , in order to improve the strength of concrete sulfite pulp waste -based reducing agent . 60 to 70 years is low tide , this time developed the accelerator and sugar- calcium -based plasticizers . 70 to 80 years is the culmination of the development of water-reducing agent , all localities and departments have developed and identified with naphthalene sulfonate formaldehyde condensates , β- naphthalene sulfonate , aromatic resins, sulfonated Guma Long , melamine- formaldehyde condensates etc. as the main component of superplasticizer than 20. Lignin sulfonate , humates ordinary water as a main component nearly 10 . Wood and calcium sulphate , naphthalene sulfonates and sulfates , sugar and calcium sulfates, and sulfates of PAHs compound as a main component , more than 10 kinds of early strength superplasticizer . Addition of molasses , sucrose , calcium lignin sulfonate naphthalene derivative is a main component retarding superplasticizer , and sodium rosin and organic , inorganic composite synthetic air entraining water reducing agent , etc. The number of new varieties all with a rate of a dozen foreign and some major varieties of substantially more than a production .
According to statistics , Chinas annual production capacity of concrete admixtures about 220 000 t, which mainly calcium lignosulfonate , sodium wood , wood magnesium salts of humic acid supplement ordinary water production capacity of 27,000 t, accounting for 12.5% of the total production capacity of admixtures . Sulfonated coal tar products, melamine formaldehyde resin , sulfonated resin supplemented Coumarone superplasticizer production capacity of 30,000 t, accounting for 13.7 percent of total production capacity of admixtures . With sodium sulfate as the main component of early strength agent early strength superplasticizer production capacity of 100,000 t, accounting for 43% of production capacity admixtures . Lime and molasses produced by the retarder and water reducer retarding production capacity is only 06,000 t. Saponification with rosin -based material produced entraining air entraining water reducing agent annual production capacity is smaller, only hundreds of t. Calcium chloride , sodium chloride , sodium nitrite as the main component of antifreeze annual production capacity of 15,000 t, accounting for 7% admixture production capacity . In alunite expanders products based accelerator annual production capacity of 22,000 t, accounting for 10% of the total production capacity of admixtures . According to the needs of economic development , according to the amount available for use 50 million t of cement admixtures meter scale concrete admixtures in China is expected to reach 280,000 need t.