Anhui Yulong New Material Technology Co., Ltd. is an enterprise specializing in anti-segregation agents and anti-segregation agents. Our company produces anti-segregation agents. This product has excellent water retention, workability, pumpability and adaptability. It can improve the water retention of concrete and mortar, avoid segregation and bleeding; improve the sensitivity of water-reducing agents and improve the anti-sag properties of accelerating agents. Used in the compounding and synthesis of water reducing agents and accelerating setting agents, it can not only improve product performance but also reduce production costs.
Concrete anti-segregation agent Anti-segregation agent improves the fluidity of concrete
Seeing the important role of water-reducing agent in improving strength and saving a large amount of cement, the construction workers It is mistakenly believed that when preparing commercial concrete using water-reducing agents, the higher the water-reducing rate, the better. Even when preparing low-grade concrete, a higher water-reducing rate is required. Normally, as the water reduction rate increases, the strength of the concrete will become higher and higher. For concrete with a high water-cement ratio, reducing water consumption will also reduce the drying shrinkage of the concrete, which is of course very beneficial to improving the strength of the concrete and reducing shrinkage and cracking of the concrete.
However, the current water-to-cement ratio in concrete construction is generally designed to be relatively low. Since self-shrinkage cannot be ignored, if water consumption is further reduced significantly, the internal dryness of the concrete will be increased. Shrinkage, thereby increasing the spontaneous shrinkage of concrete. In addition, commercial concrete preparations generally contain retarders. Due to slow hydration, the concrete will not set for a long time, and the surface of the concrete will lose water seriously, which increases the risk of shrinkage and cracking of the concrete. Of course, some people will say that we can prevent concrete from drying out and shrinking through watering and curing, but very low water glue is denser than concrete, and the watering rarely penetrates into the concrete, and it is difficult to replenish the water shortage. Purpose.
It is a common practice to reduce the amount of cement by reducing water to increase strength. However, if the amount of cement is greatly reduced and there is too little cement slurry, the cement slurry layer is too thin, which is more likely to cause micro-cracks, reduce the ultimate elongation of concrete, and reduce the tensile strength of concrete. Excessive reduction in the amount of cementitious materials will also increase the elastic modulus of concrete. When the dry shrinkage deformation and temperature deformation are the same, the deformation stress increases and concrete is prone to cracking.
Some types of water-reducing agents with high water-reducing rates have poor water retention. If excessive water reduction increases the dosage of these water-reducing agents, concrete will easily bleed. Segregation affects the homogeneity of concrete and adversely affects the quality of concrete.
The author's investigation found that commercial concrete currently suffers from more early cracking, and more than 70% of them occur in concrete using admixtures with higher water reduction rates. It is not difficult to see that it is neither scientific nor economical to use high water reduction to save large amounts of cement. Overemphasis on water reducing rate is a major misunderstanding of water reducing agents.
The use of air-entraining agents will reduce the strength of concrete
Commercial concrete can be effectively mixed with air-entraining agents It can effectively improve the workability, fluidity, pumpability, and water retention of concrete. More importantly, adding air-entraining agents to concrete can effectively improve the durability of concrete such as frost resistance and impermeability. Research also shows that adding air-entraining agents to commercial concrete can also prevent secondary adsorption of cement particles in concrete and reduce slump loss. At present, Japan and other countries have almost no concrete without air-entraining agents in concrete construction. Concrete without air-entraining agents is called special concrete.
At present, many concrete construction companies in my country have not mixed air-entraining agents. The main reason is that the construction workers believe that adding air-entraining agents to concrete will reduce the strength. This is a problem for air-entraining agents. Another misunderstanding about aerosols.
“A one percent increase in the air content in concrete will reduce the strength by three to five percent” is their theoretical basis. Yes, the strength of concrete will of course decrease as the air content increases, but that is only the test result under the premise that the water-cement ratio is the same. Commonly used air-entraining agents have a certain water-reducing function. At the commonly used dosage, the water-reducing rate of air-entraining agents is above 6%. The water-reducing effect will also improve the strength of concrete.
Some people think that adding air-entraining agents to commercial concrete will increase construction costs, but that is a one-sided view. Taking into account the water-reducing effect of air-entraining agent, for every kilogram of air-entraining agent used, more than ten kilograms of water-reducing agent can be used less while ensuring a certain water-reducing rate. The application cost will not only increase but will also decrease. reduce. Facts have proved that the technical and economic benefits of adding air-entraining agents in commercial concrete construction are very obvious.
Can commercial concrete be mixed with expansion agents?
It is more likely that engineering accidents will occur after applying expansion agents. The increasing number of concrete has caused many engineers to doubt the application effect of expansion agents, and even came to the view that "concrete will not crack without expansion agents, and the more it is used, the more it will crack." The above concepts also appear in the discussions of some experts and scholars. Whether expansion agents cannot be mixed into commercial concrete, the author believes through accident analysis that the claims that commercial concrete can be used unconditionally or cannot be mixed at all are relatively one-sided.
The first is the application scope of the expansion agent. Through the analysis of the action mechanism of the product, the author believes that it is not suitable to be mixed in high-strength and other concrete with low water-binder ratio. This is because the lower water consumption of concrete does not guarantee��Sufficient water to cause volumetric expansion efficiently. Even if watering and curing are strengthened, due to the low water-cement ratio concrete is relatively dense and has high impermeability, only a small amount of water can penetrate into the concrete, which still cannot meet the water demand for expansion. Secondly, due to the high water absorption of the expansion agent, the cement particles in the concrete cannot be fully hydrated due to lack of water, which affects the strength of the concrete.
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