Hello everyone, welcome to our website again! The news today is for a clearer understanding of concrete admixture.
Today we mentioned concrete admixture again, so first of all we need to understand what is concrete admixture. The so-called concrete admixture refers to the chemical substance that is mixed in the process of mixing concrete and accounts for less than 5% of the cement quality. It can significantly improve the performance of concrete. Adding admixtures to concrete has low investment, quick effect, and technical economy. Significant benefits. It is precisely because of this that admixtures have been used more and more. With the development of science and technology, admixtures have also changed with each passing day, and various new products have emerged in an endless stream. Let us understand the following types of concrete admixtures at home and abroad, as well as the characteristics and scope of application of various admixtures.
First of all, we divide the admixtures into four categories according to their functions:
1. Admixture to improve the rheological properties of concrete mixtures: adjust concrete setting time,
2. Admixture for hardening performance: including retarders, early strength agents,
3. Accelerators and other admixture that improve the durability of concrete: including air-entraining agents, waterproofing agents, and rust inhibitors.
5. c to improve other properties of concrete: include air-entraining agents, expansion agents, antifreeze, coloring agents, waterproofing agents and pumping agents.
Next, we will separately understand the characteristics and scope of application of the specific admixture.
Common water-reducing agent: Water-reducing agent is a concrete admixture that can reduce the water consumption for mixing while maintaining the coagulation slump unchanged. Its function is to disperse the cement particles after adding the concrete mixture, which can improve its workability, reduce the unit water consumption, and improve the fluidity of the concrete mixture; or reduce the unit cement consumption and save cement. The scope of application of ordinary water reducing agents: especially suitable for the preparation of concrete projects with high durability, high fluidity, high slump retention, high strength and high appearance quality requirements. It is extremely beneficial for the preparation of high-fluidity concrete, self-compacting concrete and fair-faced concrete.
Early-strength agent: Early-strength agent refers to an admixture that can increase the early strength of concrete and has no significant effect on the later strength. The main function of the early strength agent is to accelerate the speed of cement hydration and promote the development of the early strength of concrete. It not only has the function of early strength, but also has the function of one-definite water reduction enhancement. Its scope of application is most suitable for construction under low temperature conditions in early winter and early spring.
Retarder: Retarder is an admixture that reduces the speed and heat of hydration of cement or azurite, and extends the setting time. The purpose of adding a retarder to commercial concrete is to extend the hydration and hardening time of cement. Fresh concrete can maintain plasticity for a long time, thereby adjusting the setting time of fresh concrete. Scope of application of retarder: retarder can be used for mass concrete, roller compacted concrete, concrete constructed under hot weather conditions, concrete poured in a large area, concrete to avoid cold joints, requiring a long time to park or long-distance transportation Concrete, and other concrete that needs to delay the setting time. The retarding superplasticizer can prepare high-strength and high-performance concrete.
Air-entraining agent: In order to improve the slump, fluidity and plasticity of concrete, air is introduced into the concrete mixture during the mixing process to form a large number of tiny, closed and stable bubbles. Air-entraining agent can improve concrete slump, fluidity and plasticity. Reduce concrete bleeding and segregation and improve the homogeneity of concrete. Improve the flexural strength of concrete. When the content is 3%-5%, the flexural strength increases by 10%-20%. It can reduce the thermal diffusion and conductivity coefficient of concrete, and improve the frost resistance, salt resistance, impermeability, sulfate erosion resistance and alkali aggregate reaction performance of concrete. The scope of application of air-entraining agent: mainly used for concrete projects requiring bleeding. It is used for concrete projects with frost resistance and durability requirements such as hydraulic engineering and port engineering. Used in construction mortar and lightweight foamed concrete.
High-efficiency water reducing agent: an admixture that can greatly reduce the water consumption of the mixture under basically the same conditions of concrete collapse. The superplasticizer has a strong dispersing effect on cement, which can effectively improve the fluidity of the cement mixture and the slump of concrete, while drastically reducing water consumption and significantly improving the workability of concrete. The water reducing agent can greatly reduce the water consumption so as to significantly increase the strength of concrete at various ages. While keeping the strength constant, it can save 10% of cement or even more. In addition, the ion content of the high-performance water reducing agent is very small, so it does not corrode the steel bars. It can enhance the impermeability, freeze-thaw resistance and corrosion resistance of concrete, and improve the durability of concrete. The application range of superplasticizer is in almost all major and key projects in the country, especially in water conservancy, hydropower, hydraulic engineering, offshore engineering, bridges and other projects. Polycarboxylic acid-based water-reducing agents have been widely used.
Accelerator: Accelerator is an admixture that can quickly harden concrete. Its setting time: the initial setting is 1~5min, the final setting is 5~10min, and it is non-toxic, tasteless and non-irritating. The early strength of sprayed concrete is high, and its 28-day-old compressive strength preservation rate reaches 80-100%. The spray material has good cohesion, no corrosion to the steel bar, and improves the impermeability mark. The scope of application of accelerator: mainly applicable to those emergency repair projects, such as military airports, emergency road repairs, etc.
What we mentioned above are the most common concrete additives in the concrete and building construction process. If you want to know more detailed information and how to purchase polycarboxylate superplasticizer products, please contact us directly for more information.
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