Calcium aluminate cement provides sufficient demoulding strength for castables in a short period of time through the hydration behavior that occurs after encountering water. It is a commonly used hydrating binder for refractory castables. Calcium aluminate cement has the characteristics of good early strength, high refractoriness, erosion resistance, etc., and has become an important binder for high-performance refractory injection materials required by the current defense, metallurgy, chemical, and building materials fields.
Calcium aluminate cement was originally mainly used in military engineering. Nowadays, calcium aluminate cement is widely used in general industries. For example, in the anti-leakage treatment of construction engineering, calcium aluminate cement can be made into calcium aluminate expansion agent and calcium aluminate by adding appropriate amount of calcium aluminate cement to it. In terms of supporting, sealing and plugging the side of coal mine roadways, calcium aluminate cement can be made into high water velocity solidification and filling materials. In addition, calcium aluminate cement also has special applications such as emergency repair and construction, resistance to sulfate corrosion and construction under cold conditions: it can be used to prepare unshaped refractory materials, heat-resistant concrete, expansive cement and precast concrete industries.
The hydration of calcium aluminate cement will directly affect the construction performance of the castable, such as the fluidity, construction time and demoulding strength. The hydration of calcium aluminate cement mainly includes three stages: dissolution-nucleation-sedimentation. Cement first dissolves in water, and the surface of the particles is hydroxylated, releasing ions of Ca2+ and Al(OH)4-. When the concentration of the solution reaches a certain value, a small amount of hydration products will be produced; the hydration products will nucleate to obtain the size and number of crystals; after the nucleation is completed, the hydration products will precipitate out of the water. The hydration rate of calcium aluminate cement is very fast. This is because the hydration of calcium aluminate cement and the dissolution of CA proceed at the same time. The hydrated minerals will not form a compact structure on the surface of the unhydrated minerals, which hinders the further process of hydration reaction.