Compound Use of Amorphous calcium aluminate and Tartaric acid
Key words
Amorphous calcium aluminate, tartaric acid, L-tartaric acid, accelerator, retarder, concrete, compound
As we all know, because the atoms, ions, and molecules inside the amorphous calcium aluminate phase have no periodic arrangement, are disordered, and have no fixed shape, the hydration activity of amorphous calcium aluminate is higher than that of crystalline one. After crystalline calcium aluminate is used as a concrete accelerator, it can replace part of Portland cement, which can significantly improve the hydration reaction rate of cement, that is, a certain proportion of amorphous calcium aluminate can catalyze the hydration reaction of Portland cement. Efficiency, that is, rapid setting.
Amorphous calcium aluminate is the latest concrete quick-setting admixture. Because of its excellent quick-setting effect and wide compatibility with other materials, it can be said that amorphous calcium aluminate is one of the best concrete quick-setting admixtures at present.
Its advantages are as follows:
The initial setting time is very short, the strength develops very fast, and the later use effect is stable;
High later strength and no shrinkage;
Excellent frost resistance and impermeability;
good corrosion resistance;
It can reduce the cracks caused by the drying shrinkage of the cement and increase the compactness of the cement;
It has a certain chemical prestress, which can strengthen the toughness of cement and improve the durability of cement.
Therefore, amorphous calcium aluminate can be widely used in winter concrete construction, underwater engineering, marine engineering, emergency repair and construction projects, etc.
However, since amorphous calcium aluminate has an extremely excellent quick-setting effect, and as the content of amorphous calcium aluminate increases, the setting time will also be sharply accelerated. When the dosage exceeds a certain proportion, the setting time will be too fast, but the operability will be lost, and it cannot be used for construction work.
Therefore, it is necessary to add a cement retarder to prolong the setting time of the concrete, so that the fresh concrete can maintain its plasticity for a long time. According to the experiment and application experience, L-tartaric acid is the best compound additive for amorphous calcium aluminate. Tartaric acid can control the setting time of concrete well, and the setting time can be adjusted freely within 1 hour.
