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When are retarding additive used on concrete?

2024-05-31 10:40:46  Blog

Concrete Retardation Additives are used in specific situations to optimize workability, improve workability and extend the setting time of concrete. The following is a detailed discussion of when to use retarder additives for concrete, including their application scenarios, mechanism of action, selection, and use considerations.


Concrete retarder additive is a chemical admixture that can prolong the setting time of concrete. In concrete projects, due to high temperatures, large-scale construction, or other specific needs, concrete is easy to set prematurely, resulting in increased construction difficulty, quality degradation, and other problems. At this time, the use of retarder additives can effectively deal with these challenges, to ensure the quality and efficiency of concrete construction.

Second, the application of concrete retarder additive scenarios

Concrete construction in hot weather

Under high temperature environment, the hydration reaction of cement will be accelerated, resulting in the shortening of concrete setting time. This will bring great inconvenience to the construction, such as reduced fluidity of concrete and pouring difficulties. At this time, the use of retarder additives can significantly extend the setting time of concrete and improve the construction efficiency and quality. For example, in summer high-temperature construction, adding a retarder can slow down the concrete setting speed, extend the construction time, improve the construction quality, and reduce the risk of thermal cracking of concrete.

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 Large structure or anti-rendering concrete construction

During the construction of large structures or anti-rendering concrete, if the setting time of the concrete is too short, thermal cracks or shrinkage joints are likely to occur. These cracks can seriously affect the durability and safety of the concrete. In order to solve these problems, retarder additives can be added to the concrete to prolong the setting time and reduce the cracks.

 Tunnel or subway construction

In underground tunnels or subway construction, due to the complex environment and long construction period, we need to ensure that the concrete is in a longer period to maintain fluidity. At this time, the use of retarder additives can extend the setting time of concrete to ensure the smooth progress of construction.

Third, the role of the concrete retarder additive mechanism

Retarder additives, mainly through the following ways, play a role:

Retard cement hydration reaction

Retarder additives can slow down the speed of cement hydration reaction, thereby extending the setting time of concrete. This is mainly because the retarder additives can have a chemical reaction with certain components in the cement, reducing the rate of cement hydration reaction.

Change the internal structure of concrete

Retarding additives can also change the internal structure of concrete to make it more stable. For example, some retarder additives can increase the porosity of concrete and reduce the degree of stress concentration within the concrete, thereby improving the crack resistance and durability of concrete.

Fourth, the selection of concrete retarding additives and the use of precautions.

 Selection of suitable retarder additives

In the selection of retarder additives, should be selected according to the specific requirements and construction conditions. Generally speaking, the concrete strength and durability of retarder additives have less impact.

 Control the dosage

The dosage of retarder additives should be accurately controlled, too high or too low dosage will have a negative impact on the performance of concrete. A high dosage will lead to a long concrete setting time, affecting the construction progress; too low a dosage can not achieve the desired effect.

 Pay attention to the timing

Retarder additive timing is also very important. Generally speaking, retarder additives should be added in the appropriate period after mixing cement and aggregate to ensure that the retarder additives fully react with the cement.

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Compliance with safety regulations

When using retarder additives, relevant safety regulations and operating procedures should be observed to avoid harming human beings and the environment.


Concrete retarder additives are used under specific circumstances to optimize the construction performance of concrete, improve workability, and extend setting time. When selecting and using retarder additives, they should be selected and controlled according to specific use requirements and construction conditions to ensure the quality and efficiency of concrete construction.

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  • Luoyang Tongrun Info Technology Co., Ltd. ( is the world's leading nanomaterial technology developer and application manufacturer, the company has more than 20 years of industry experience, after years of scientific research and production, has been professionals in lightweight concrete and foam concrete solutions. We can supply concrete foaming agents, superplasticizers, aerogels and foam concrete strength enhancers for lightweight concrete mix, CLC blocks all over the world, suitable for ordinary cement foamed concrete cast-in-place, block, plate, insulation wall, etc.