When the expanded concrete is under the condition of zero degree, the cementing agent such as cement and expansive agent can still be hydrated, but the hydration rate is lower than that of the expanded concrete under the condition of zero degree or more. The main reason is that the hydration reaction of cement and expansion agent is more than zero conditions under the conditions of the slow, but the negative temperature conditions of the two hydration can be basically coordinated. Showing the strength with the negative temperature hydration process and slowly increase the limit expansion rate also has a certain development. There is a significant increase in the intensity of negative temperature to positive temperature, while the expansion rate also increased significantly, all under the negative temperature of the maintenance of the specimen into the positive temperature, there is no cracks, indirectly confirmed in the negative Temperature conservation and negative temperature into the positive temperature of the entire conservation process, the expansion and intensity of the development is always coordinated development. The addition of expansion agent improves the working performance, strength properties and durability of high strength concrete, so that high performance concrete has been widely used at home and abroad. With the modern building structural engineering requirements for concrete performance, such as high strength, high durability (including high impermeability, low deformation) and high workability, and concrete commonly used pumping construction process, the expansion of concrete Development to enter the high performance category. It is an important research direction to study the expansion agent which is more suitable for high performance concrete. tools for cutting concrete eqtupment metalworking equipment auctions used automotive machine shop equipment for sale equipment at asphalt street pavement