The initial use of concrete admixtures is only to save cement. With the development of building technology, admixture has become the main measure to improve the performance of concrete.

Because of the high efficiency water reducing agent, large fluidity concrete, self compacting concrete and high strength concrete have been applied. Because of the thickening agent, the performance of underwater concrete is improved. Because of the retarder, the setting time of cement can be prolonged, it is possible to reduce the slump loss and prolong the construction operation time. The antifreezing agent, the freezing point of the solution can be reduced, or the ice crystal structure will not cause freezing damage.

Generally speaking, concrete admixtures play the following roles in improving the performance of concrete.

1. the water consumption of concrete can be reduced, or the fluidity of concrete can be increased without increasing water consumption.
2. he setting time of concrete can be adjusted.
3. reduce bleeding and segregation. Improve workability and water resistance.
4. the slump loss can be reduced and the pumping ability of the pumped concrete can be increased.
5. shrinkage can be reduced. Adding expansive agent can also compensate for shrinkage.
6. delay the initial hydration heat of concrete, reduce the temperature rise rate of mass concrete and reduce the occurrence of cracks.
7. improve the early strength of concrete and prevent freezing under negative temperature.
8. increase strength, increase frost resistance, impermeability, abrasion resistance and corrosion resistance.
9. control alkali aggregate reaction, prevent corrosion of steel bar and reduce chloride diffusion.
10. concrete made of other special properties.
11.  reduce the viscosity coefficient of concrete and so on.