Concrete is a compositional mixture consisting of a whole mass of materials and sometimes additives, among which the main cement of high quality, gravel of granite stone and pure enriched sand are the main. The main characteristic of concrete can be called its ability to withstand heavy loads — compression strength, that is, the largest load of the load per 1 square centimeter of the area of the concrete surface. Because of this, concrete is divided into eight marks: M75, M100, M150, M200, M250, M300, M350, M400. Each type of cement or each brand has its maximum opportunity to withstand compression strength, so concrete is assigned a class from indication (letter “B”) and numerical value from 5 to 30. At the same time, numbers indicate the level of pressure in megapascli, which can withstand the concrete class.