Concrete admixture is a chemical substance that is added during the mixing of concrete, cement paddle or mortar, before mixing or in additional mixing to improve the performance of concrete. In special cases, the amount added generally does not exceed 5% of the cement quality. At present, in response to various special requirements of concrete engineering, many kinds of admixtures have been developed to meet various requirements. Adding them to concrete in an appropriate manner can achieve some expected effects.
According to the function of these additives, they can be divided into water reducer, accelerator, retarder, air-entraining agent, waterproof agent, binder, expansion agent, rust inhibitor, defoamer, mold release agent, colorant ,
Among the concrete admixtures, the most striking is the high-efficiency water-reducing agent. The development of superplasticizers has a history of nearly 40 years. In 1962, Japan’s Kenji Hattori held an important position in naphthalene superplasticizer. In 1963, the original Federal Germany successfully developed melamine sulfonate formaldehyde condensate.
Because these two additives have a strong dispersion effect on cement, the performance is significantly improved compared with ordinary water-reducing agent, so it is called high-efficiency water-reducing agent. The advent of superplasticizer is the third breakthrough in concrete modification after reinforced concrete and prestressed reinforced concrete. It is with the advent of superplasticizers that high-strength concrete and fluid concrete become a reality. Its development promotes the high-strength and super-high strengthening of concrete, improves the construction of concrete, and realizes the large-scale modern high-speed, efficient and civilized construction, thus promoting the rapid development of concrete technology.
High-efficiency water-reducing agent has a strong dispersing effect on cement, which can greatly improve the fluidity and slump of the cement mixture, while greatly reducing the water consumption, and significantly improve the working performance of the fresh concrete and the strength of the concrete at all ages
