What is the original use of concrete admixtures? Do you know?

What is the original use of concrete admixtures? Concrete admixtures were initially used just to save cement. Concrete admixtures can reduce the amount of cement and improve the overall performance of concrete. Therefore, concrete admixtures have become an indispensable part of concrete and are widely used in various construction projects. With the development of concrete technology, the addition of admixtures has become the most important method to improve the performance of concrete. Due to the high-efficiency water reducing agent, high-fluidity concrete, self-compacting concrete, and high-strength concrete are widely used; due to the thickening agent, the performance of underwater concrete can be improved; due to the retardant, the setting time of concrete has been improved Only by extending it can we reduce the slump loss of concrete and extend the effective construction time of concrete; due to the antifreeze, the freezing point of the solution can be lowered, and the deformation of the ice crystal structure will not cause freezing damage, so that construction can be carried out at negative temperatures.

Generally speaking, concrete admixtures have the following functions in improving and enhancing the functions of concrete.

　(1) It can reduce the water consumption of concrete and increase the fluidity of concrete without increasing water consumption.

(2) The setting time of concrete can be flexibly adjusted.

(3) Reduce the bleeding and segregation of concrete and improve the workability of concrete.

　(4) It can reduce the slump loss of concrete and increase the pumpability of concrete.

　(5) It can reduce the shrinkage of concrete, and adding expansion agent can also compensate for the shrinkage.

(6) Delay the initial hydration heat of concrete, reduce the temperature rise rate of large-area concrete, and reduce the occurrence of temperature cracks.

(7) Improve the early strength of concrete and prevent concrete from freezing at negative temperatures.

(8) Improve the strength of concrete and effectively increase the frost resistance, impermeability, abrasion resistance and corrosion resistance of concrete.

(9) Control the alkali-aggregate reaction to prevent corrosion of steel bars and reduce the diffusion of chloride ions.

(10) Concrete can be made into other special functions.

　(11) Effectively reduce the viscosity coefficient of concrete, etc.

After adding concrete admixtures to concrete, the effects will be different due to different types. Most of them produce physical effects, such as adsorbing on the surface of cement particles to form an adsorption film, which changes the potential and produces different suction or repulsion forces; some will destroy the flocculation structure, increase the stability of the cement diffusion system, and improve the conditions for cement hydration; Some can form macromolecular structures and change the adsorption state on the surface of cement particles; some can reduce the surface tension and surface energy of water; and a few can directly participate in chemical reactions and form new compounds with cement.

Because admixtures can effectively improve the functions of concrete and have significant economic benefits, they are widely used in many countries and have become an indispensable key material in concrete. Especially with the use of high-performance reducers, cement particles can be fully dispersed, water consumption is greatly reduced, and the potential of cement is fully utilized, causing the concrete to become denser and the microstructure of the pore interface zone is well improved, thus making The physical and mechanical properties of concrete have been greatly improved. Whether it is impermeability, chloride ion diffusion, carbonization, resistance to sulfate corrosion, impact resistance, wear resistance, etc., they are significantly better than concrete without concrete admixtures. .

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