Calcium sulfoaluminate (CSA) binder is made by directly grinding ultra-high-strength cement clinker particles into powder, without adding other materials such as limestone, slag, or gypsum. Its physical and chemical properties are similar to ultra-high-strength cement, with grades of 62.5MPa, 72.5MPa, 82.5MPa, and 92.5MPa. It is mainly used as an admixture in various cement and mortar products.
Calcium sulfoaluminate (CSA) binder is a hydraulic material based on calcium sulfoaluminate, different from calcium aluminate cement (based on calcium aluminate) or Portland cement (based on calcium silicate). CSA ultra-high-strength cement can be used alone (lithium salts can serve as early-strengthening agents) or combined with one or more materials such as hard gypsum, Portland cement, or kaolin.
The properties of CSA binder make it suitable for products requiring early strength, high strength, and rapid setting, such as rapid-hardening cement, self-leveling materials, concrete repair materials, grouts, waterproof and leak-stopping materials, and high-strength concrete. When applied in these products, CSA binder endows them with controllable initial/final setting time, high early strength, micro-expansion during hydration, shrinkage compensation, and certain sulfate corrosion resistance.
The most representative mineral component in CSA binder is ettringite—a crystalline material with expansion properties formed by the chemical reaction of limestone, hard gypsum, and bauxite. Its volume is twice that of all mineral components before the reaction. During CSA binder production, 85% of ettringite is formed in the early production stage (before the hydration of aluminates and silicates), and the possibility of ettringite formation in the later stage is extremely low. Thus, the formed ettringite has long-term stability, which is the main difference between CSA binder and calcium aluminate cement.
Whether added to mortar, concrete, or composite cement, CSA binder accelerates the initial/final setting time and improves early strength, while having almost no impact on later strength. Depending on the dosage, it also provides shrinkage compensation or expansion properties.
In addition, CSA binder has the properties of low carbon emissions, sulfate corrosion resistance, low permeability, high durability, and low-temperature resistance.
