1. Why does the surface of cement refractory castables powderize? 1. Influence of ambient temperature and humidity Cement refractory castables are more likely to powderize when the ambient temperature and humidity are high. This is because when the humidity is high, water and carbon dioxide in the air can easily enter the green body through the pores, promoting the occurrence of destructive reactions. Therefore, it is recommended that the protective temperature be controlled at 15-20°C, and the protective temperature of large prefabricated blocks should be around 30-35°C to enhance the strength and service life of the green body and reduce the powdering phenomenon. 2. Surface powdering caused by alkali impurities The formula of refractory castables contains soluble alkali metal impurities such as sodium and potassium, which are important factors leading to the powdering of the castable surface. Especially in low-grade refractory raw materials, the content of alkali metal impurities is high, so that the sodium ions on the surface of the green body react with carbon dioxide in the air to form carbonates. This type of reaction continues, causing the green body to be damaged from the outside to the inside. Using raw materials with lower alkali content and controlling the addition of cement can effectively reduce the powdering phenomenon. 3. Low density of green body Low density of green body increases porosity, water and carbon dioxide in the air can easily diffuse into the green body, and promote pulverization reaction. Therefore, it is recommended to select high-density raw materials and compact them appropriately during construction to reduce porosity and improve the durability of castables. 4. Impact of water addition during construction Adding more water during construction will improve the construction performance of castables, but at the same time it will have certain side effects on the initial strength and density of green body, and will also increase hydration reaction, which is easy to cause surface pulverization. Controlling the amount of water added during construction and using water in an appropriate proportion as much as possible can effectively reduce the risk of pulverization. 2. Precautions for daily protection In order to prevent the surface pulverization of cement refractory castables, daily protection work is also crucial: 1. Storage environment: Store low-cement refractory castables in a closed and ventilated space. Prevent direct sunlight and moisture, and keep the storage environment dry. 2. Storage container selection: Use sturdy storage bags to prevent the bags from being damaged and causing debris to enter the castables. 3. Regular inspection: Regularly check the storage status of the castables and deal with any problems found in a timely manner to avoid the accumulation of problems and more serious damage. By controlling the ambient temperature and humidity, reducing the content of alkali impurities, increasing the density of the green body and reasonably controlling the amount of water added during construction, the surface powdering of cement refractory castables can be effectively prevented and their service life and performance can be improved.