Grades, classes, characteristics and purpose of concrete
Monolithic frame construction technology is currently the most popular among developers in Ukraine. The main material used for this type of construction is concrete. Today we will analyze how concrete brands differ, what differences they have and their purpose.
The main characteristics of concrete are its strength, mobility, water resistance and frost resistance.
The strength of concrete corresponds to its class and is determined by several criteria:
- Compressive strength. It is calculated when a cubic concrete sample is compressed by a press 150×150 mm. At the same time, the concrete must be aged for 28 days after low tide.
- Flexural tensile strength. This characteristic is taken into account during the design work. Its calculated values can be obtained in the relevant design institutes, because it is quite difficult to create the conditions necessary for testing in the laboratory.
- Transmission strength. This characteristic indicates the strength of concrete at the moment of compression when transferring the reinforcement stress to concrete.
Mobility is the ability of a mixture to spread out under its own weight. There are 4 degrees of mobility: Less than 1-2 cm, less than 10 cm, less than 10-15 cm and less than 20 cm.
Water resistance is determined by the number of atmospheres in which concrete does not let water through. To increase this parameter, special additives are used that create a system of closed pores in the material.
Frost resistance is the ability to withstand repeated freezing and thawing in a water-saturated state without significant loss of strength.
Below we will consider the main grades and classes of concrete:
M-100 (B 7.5) is mainly used for preparatory work. The mixture is applied in a thin layer on a sand cushion, after which reinforcement work begins and the pouring of more durable concrete mixtures.
M-150 (B 12, B 12.5) is also used for preparatory work, floor screeds, foundations of small structures and road surfaces.
M-200 (B 15) is probably the most popular brand of concrete. It is used for the construction of floor screeds, foundations, blind areas, paths, stairs, etc.
M-250 (B 20) is used for the manufacture of monolithic foundations, blind areas, paths, stairs, retaining walls.
M-350 (B 25) is used in the creation of monolithic foundations, pile-grillwork reinforced concrete structures, floor slabs, columns, crossbars, beams, monolithic walls, basin basins and other critical structures.
M-400 (B 30) can already be used for the construction of bridge structures, hydro-technical structures, special reinforced concrete structures, columns, crossbars and beams with enhanced characteristics.
Concretes of higher grades are used in cases with specific requirements, for example, in the construction of dams, subways, bank vaults.