What is the composition of cement and its main components?

The main components of cement are lime, silica, alumina, and iron oxide.
The four main compounds in cement are tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite.
The presence of C3A in cement is not desirable because it contributes little to its strength and can cause cracking when exposed to sulfates.
The hydration of cement with water generates the hardened cement paste, which is the most important material in practice.