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1. Fast setting time
According to the provisions of GB175-2007, the initial setting time of all kinds of sulphoaluminate cement shall not be less than 45min and the final setting time shall not be more than 10h. But for CSA cement, the initial setting time and final setting time are mostly 30min~40min and 55min~75min.
2. High early intensity
Compared with ordinary sulphoaluminate cement, CSA cement develops rapidly in strength and has a very high 1d strength and 3d age strength, which can reach more than 85% of the 28d strength of sulphoaluminate cement. Because the clinker contains a certain amount of C2S, the strength of CSA cement will increase slowly in a later period, and it will not result in the phenomenon of later strength shrinkage as which will happen to some types of accelerated cement, quick hardening cement, and early-strength cement.
3. Certain free swelling ratio
CSA cement has a certain free expansibility because the ettringite produced by the hydration of it will swell as the crystals grow. When the ratio of ash to sand (C/S) is 1:0.5, the free swelling ratio is 0.00%~0.10% for 28d low alkali CSA cement and 0.00%~0.07% for 28d quick hardening CSA cement, which indicates that although CSA cement has certain expansibility, its swelling ratio is relatively low and the application is very safe.
4. Low liquid-phase basicity
The pH value of sulphoaluminate cement hydration liquid reaches about 13, while the pH value of CSA cement hydration liquid is 11.5~12.0. Low alkali cement is suitable for the cementitious material of glass fiber composite material. It can become an ideal cementitious material for glass fiber products if adding a certain proportion of mixed materials, such as limestone, fly ash, and slag powder, in CSA cement to further reduce the alkalinity.
5. Good freezing and thawing resistance
Good freezing resistance is also one of the excellent properties of CSA cement. Due to its characteristics of fast hardening and early strength, there is little influence on its strength in the early freeze. If ordinary sulphoaluminate cement is frozen in the early stage, when the temperature returns to normal, about 50% of the strength will be lost, while for CSA cement, only 9% will be lost. The early strength of CSA cement is 5 to 8 times that of ordinary sulphoaluminate cement if it is used in a low-temperature environment where the temperature range is from 0℃ to 10℃; when it is used in an environment where the temperature range is from -20℃ to 0℃, the strength of concrete (3~7 days) can reach 70%-80% of the designed strength if adding a small amount of antifreeze and keeping the mold temperature above 5℃.
