Cement is one of the main materials during the construction and repair of apartments. With the correct selection of cement, you can save on price, not the quality of the material. It happens that it is different and under different brands. Slag Portland cement is produced under stamps (300, 400, 500,600). It grabs from 45 minutes to 6 hours. There should not be lumps in its composition, their presence speaks of poor quality of cement and its incorrect storage. Such cement is mainly used underground and under water.