Additives are increasingly widely used, which is the objective requirement of the development of construction engineering structure and technology.
In recent years, there are high-rise, long-span and various new structural systems in the integral cast-in-place concrete structure, many large-scale, thin-walled and other new component types in the prefabricated precast concrete components, and new construction technologies such as mass concrete, shotcrete, vacuum water absorption concrete and slip form construction concrete in the concrete construction. Therefore, for the concrete The performance requirements of large fluidity, early strength, high strength, quick setting, slow setting, low hydration heat, frost resistance, impermeability, etc. are put forward. The admixture is just to improve the performance of concrete, improve the project quality, reduce the project cost, and promote the requirements of new technology.
The performance of concrete is determined by the proportion of cement, sand, stone and water. In order to improve a certain performance of concrete, the proportion of raw materials can be adjusted. But this often leads to another aspect of loss. For example, in order to increase the fluidity of concrete, the amount of water can be increased, but this will reduce the strength of concrete.
In order to improve the early strength of concrete, the amount of cement can be increased, but in addition to increasing the cost, it may also increase the shrinkage and creep of concrete.
The use of additives can avoid the above defects. In the case of little impact on other properties of concrete, the use of concrete additives can greatly improve a certain performance of concrete.
For example, as long as 0.2% - 0.3% calcium lignosulfonate water reducer is added into concrete, the slump of concrete can be increased by more than one time without increasing the amount of water; the combination of polycarboxylate water reducer and polycarboxylate slump protector can prolong the flow time of concrete.
