It is generally believed that C3S is hydrated quickly, and layered and gelatinous Ca(OH)2 is produced in the process of hydration, which plays a role in filling and compacting the fibrous and flaky skeleton gaps formed in the early stage of cement hydration. It is the backbone of strength, with good wear resistance and small shrinkage. However, from 3d to 28d, with the increase of C3S content, the increase rate of flexural strength of cement decreased and the increase rate of compressive strength increased obviously, indicating that the brittleness of cement paste increased and the crack resistance became worse. In addition, the hydration heat release and heat release rate of C3S are greater than C3A, which is not conducive to the construction of mass concrete. The hydration rate of C2S is very slow, which is about 1/20 of C3S. The biggest advantages of C2S are low hydration heat, good water resistance and high later strength, and it can catch up with C3S after 1 year. In addition, the drying shrinkage of C2S is the smallest, and the shrinkage value after 28 days of hydration is about 1/4 of C3S. Some people think that C2S contributes more to the flexural strength of cement paste than the compressive strength at the initial stage of hydration, and it is the main mineral of water-based cement with low demand. For a long time, it has been considered that C4AF mainly has good wear resistance. According to the test data of Nanjing University of Chemical Technology, when 1%C4AF in cement increases, the wear coefficient decreases by 0.0 14% ~ 0.033, which is 7 ~ 17 times of the decrease value when 1%C4AF increases. Therefore, it should be affirmed that C4AF plays a more important role in the wear resistance of cement paste than C3S. In addition, compared with C3A, C4AF not only has higher early strength, but also can increase its later strength. The contribution of C4AF to the flexural strength is much greater than the compressive strength, that is, the brittleness coefficient is particularly low. Another important function of C4AF is to generate gelled ferrite, which makes the cement paste have great deformability, as shown in Table 2. However, if C4AF is too high, it will cause great difficulties for clinker calcination and cement grinding.