Under the current trend of advocating energy conservation, emission reduction, and low-carbon environmental protection in the country, the production of traditional Portland cement is facing huge challenges. Compared with Portland cement, sulphoaluminate cement has significant advantages in energy saving and low carbon. Not only is the calcination temperature 100-150℃ lower than that of Portland cement but also the CO2 emissions are significantly reduced. It is a low-carbon cement with broad prospects. Sulfoaluminate cement is a water-hardening binder material made by mixing the appropriate proportions of limestone, bauxite, and gypsum as raw materials and calcining them at low temperature (1300-1350℃) to form clinker mainly composed of anhydrous calcium sulphoaluminate and dicalcium silicate. It is then ground together with a suitable amount of gypsum. This type of cement has the characteristics of high early strength, rapid setting, low alkali content, slight expansion, good erosion resistance and frost resistance, and is widely used in special projects such as winter construction, fast construction, repair and maintenance, marine and underground projects.
The super high-strength sulphoaluminate cement is widely used in products such as cement self-leveling mortar, non-shrinkage grouting material, ceramic tile adhesive and jointing agent, external wall insulation system material, waterproof and seepage-proof material, and rapid repair material, greatly improving the comprehensive performance of the products and receiving high praise during practical application.
Adjust the condensation time and improve early strength. The main hydration minerals of super high-strength sulphoaluminate cement are C4A3S and C2S. CaSO4 and Ca(OH)2 generated by the hydration reaction of CaSO4 and C3S in Portland cement can accelerate the condensation of C4A3S to rapidly form monosulfate. After CaSO4 is consumed by C4A3S in Portland cement, it is insufficient to play the expected retarding effect. At the same time, the hydration of C3S is accelerated, so the hydration products on the surface of the two types of cement particles interact violently with each other, greatly accelerating the hydration rate and shortening the condensation time.
Increase surface density. The combined action of C-S-H generated by the hydration of Portland cement and 3CaO·Al2O3·3CaSO4·32H2O generated by the hydration of super high-strength sulphoaluminate cement can greatly reduce the cement stone porosity, increase density, and improve mechanical strength.
Reduce shrinkage and prevent cracking. In the Portland cement-super high-strength sulphoaluminate cement-gypsum ternary system, it can effectively reduce plastic shrinkage and drying shrinkage after hardening, solve the problem of significant shrinkage caused by excessive water-cement ratio in flowable mortar, and prevent cracking.
Improve rheological properties. It has been proved in practice that in the Portland cement-super high-strength sulphoaluminate cement-gypsum ternary system, super high-strength sulphoaluminate cement can increase fluidity within a certain range and improve rheological properties.