Air Entraining Agent

Construction Chemicals

Air Entraining Agent

Air-entraining agent is a kind of surfactant, common types are rosin resin, alkyl and alkyl aromatic sulfonic acid. The air-entraining agent introduces a large number of tiny bubbles in the mortar, improves the compatibility of the mortar, reduces the resistance in the process of pumping and spraying, and reduces the clogging phenomenon; it makes the construction of the mortar lighter and smoother..

Improves the workability of dry mortar

The admixture of air-entraining agent makes the concrete mix form a large number of tiny closed bubbles, these micro-bubbles as ball – like, reduce the friction resistance between the aggregate particles, so that the fluidity of the concrete mix increased. If you keep the fluidity unchanged, you can reduce water consumption. At the same time, due to the uniform distribution of water on the surface of a large number of bubbles, which allows free movement of water to reduce the amount of wet mortar water secretion is therefore reduced, and water retention, cohesion and consequently improved!

Improve the impermeability and freezing resistance of mortar

Air-entraining agent makes the concrete mix water secretion reduced (general water secretion can be reduced by 30% -40%). Therefore, the capillary of the water secretion channel is also reduced accordingly. At the same time, the presence of a large number of closed micro-bubbles, blocking or isolation of the mortar capillary seepage channels, changing the pore structure of the mortar, so that the mortar seepage and freezing resistance is improved.

Good bubble stabilising effect

A good air-entraining agent has a very good bubble stabilising effect, introducing bubbles without breaking them. It can effectively improve the coating rate of mortar, the output of aerated bricks

Adding high-performance air-entraining agent with excellent bubble-stabilising property can introduce more small, stable and reasonable distribution of bubbles in concrete, so that the hardened concrete will have smaller bubble spacing coefficient and the durability of concrete will be more excellent.

FAQ

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What is an air-entraining agent？

Air-entraining agent, also known as aerating agent, is a kind of surfactant, which is dissolved in water and added into the concrete mix, and can produce a large number of tiny bubbles in the mixing process. Air-entraining agent can improve the fluidity, cohesion and water retention of concrete mixture, improve the fluidity of concrete, in the mixing process of concrete mixture to introduce a large number of uniformly distributed, closed and stable micro-bubbles of the admixture.

What are the advantages of air-entraining agent?

High-efficiency air-entraining agent is a kind of hydrophilic surfactant, which can be mixed into the concrete to introduce independent closed and uniformly small air bubbles, effectively improve the compatibility of concrete, and significantly improve the durability of concrete.

What are the disadvantages of air-entraining agents in mortar？

Reduces the strength of dry mortar：
Due to the presence of a large number of air bubbles, reducing the effective force area of mortar, so that the strength of concrete is reduced. However, the air-entraining agent has a certain water reduction effect (especially like the air-entraining water reducing agent, the water reduction effect is more significant), and the reduction of the water-cement ratio makes the strength to be compensated to a certain extent. However, the addition of air-entraining agent will still make the strength of mortar decreased, especially compressive strength. Therefore, the dosage of air-entraining agent should be strictly controlled, and the optimal addition amount can be determined by testing the air content of the mortar, the construction performance and the related strength. In addition, due to the presence of a large number of air bubbles, the elastic deformation of the mortar increases and the modulus of elasticity decreases, which is favourable to improving the crack resistance of the mortar.

Mechanism of air-entraining agent

Most of the air-entraining agent is anionic surfactant, will significantly reduce the surface tension of water, so that the coagulation in the mixing process to produce a large number of fine bubbles, these bubbles have the same charge of the orientation of the adsorption layer, so mutual exclusion and can be uniformly distributed; on the other hand, many anionic air-entraining agent in the calcium content of the cement aqueous solution has a calcium precipitation, adsorbed in the bubble film, can effectively prevent the bubble burst, the introduction of fine and uniform bubbles can be stable for a certain period of time. The introduction of small uniform bubbles can be stable in a certain period of time.

The interfacial activity of air-entraining agent is similar to that of water-reducing agent: the difference is that the interfacial activity of water-reducing agent mainly occurs on the liquid-solid interface, while the interfacial activity of air-entraining agent mainly occurs on the gas-liquid-solid interface. The main role of air-entraining agent is firstly to introduce air bubbles, followed by dispersion and wetting.

Air Entraining Agent

Construction Chemicals