Gas content of concrete

In the process of concrete production and transportation, sometimes there will be a significant difference between the gas content of the output machine and the gas content of the pump to the site. For example, the gas content of the concrete is 2 when it is delivered, but the gas content reaches 6-7 when it is pumped to the site. What has caused this change?

First, it has to do with sand. Sand is an important aggregate in concrete, but its particle size and shape, mud content and other factors will affect the gas content of concrete. If the sand has a high mud content, then when mixed with the cement slurry, the mud will absorb and encapsulate a part of the gas, resulting in an increase in the gas content of the concrete.

Secondly, the type and quality of coal ash is also a key factor affecting the gas content of concrete. If the coal ash used is not raw ash, but a composite coal ash that has been milled, then its active composition and fineness will be different from the original coal ash. These differences may affect the interaction between coal ash and cement hydration products, which in turn affects the gas content of concrete.

Finally, the type and amount of admixtures in concrete will also have an impact on the gas content. For example, if the concrete is added to the nano admixture, this admixture usually increases the fluidity of the concrete, but also introduces a certain amount of gas. Therefore, the type and dosage of admixtures are factors that need to be strictly controlled.

To sum up, the difference in gas content between the concrete extractor and the pumping site may be the result of many factors such as the quality of sand, the type and quality of coal ash and the type and amount of admixtures. In order to ensure the stable quality and performance of concrete, these factors need to be fully controlled and adjusted.