What effect does air-entraining agent have on the performance of fresh concrete?

How does the air-entraining agent affect the performance of fresh concrete?

During the concrete mixing process, adding a trace amount of air-entraining agent can introduce an appropriate amount (according to the volume ratio) into the fresh and hardened concrete. Total amount) tiny independently distributed bubbles. The characteristics of these bubbles are: tiny, closed, and disconnected. After these bubbles are introduced into the concrete, the capillaries become thin, tortuous, dispersed, and the penetration channels are reduced. The fine bubbles introduced by the air-entraining agent are like ball bearings in fresh concrete, helping to fill the gaps between aggregates and cementitious materials, which can increase the slump of fresh concrete; because the bubbles are wrapped in the cementitious material slurry, they are equivalent to Increasing the volume of fresh concrete cementitious material slurry can improve the workability of concrete; it can effectively reduce the bleeding of fresh concrete and avoid segregation, thus making up for the structural defects of concrete and improving the compactness and impermeability of concrete.

At the same time, because the air-entraining agent introduces air into the concrete, it can reduce concrete cracks caused by the high hydration heat of cement concrete. Engineering practice has proven that concrete air-entraining agents can improve the durability of concrete, and adding air-entraining agents has become the most effective measure to improve the frost resistance of concrete. High-quality air-entraining agents can improve the impermeability of concrete and help reduce the harmful expansion effect caused by alkali-aggregate reactions. Air-entraining agents with excellent performance can effectively improve concrete bleeding. Adding air-entraining agents can prevent the occurrence of concrete bleeding. .

What is the impact of air-entraining agents on the compressive strength of concrete?

Air-entraining agents increase the number of bubbles in the concrete, thereby reducing the effective area of ​​the slurry, resulting in concrete resistance reduction in compressive strength. As a general rule, as stipulated in the technical specifications for the application of concrete admixtures, if the air content of concrete increases by 1%, the compressive strength of concrete will decrease by approximately 4% to 6%, and the flexural strength will decrease by 2% to 3%. Air-entraining agents have a certain water-reducing effect. In practical applications, if an appropriate amount of air-entraining agents is added, the strength of concrete will increase slightly within a certain range of air content. </p