Concrete is an artificial building material obtained by the formation and further solidification of a rationally selected and compressed mixture. It consists of cement or other binders, as well as small and large aggregates with the addition of water. In some cases, where a special density of concrete is needed, for example, in asphalt concrete technology, water is not added, but special additives are used.
Its main advantages are environmental friendliness, as well as the availability of a huge raw material base. It is possible to use it in different operating conditions. It can be called universal material, which is intensively used in all areas and industries of construction. It is chemically and heat-resistant, sound-absorbing and does not conduct nuclear radiation.
Mixing sand, cement, water and gravel allows you to get the required density of concrete. The ratio will depend on the moisture content of crushed stone and sand, brand of cement and fractions. In some cases, the amount and composition of additives will affect it: water repellents, plasticizers, etc. For example, to obtain the density of M200 concrete, 400 grade cement is used.
One of the important characteristics of this material is the water-cement ratio. There is a direct relationship between water / cement. That is, the smaller this ratio, the stronger the concrete. A material having a density of 200 has a considerable mass (this is its only "minus"). It reaches 2400 kg / m3. This concrete is excellent for supporting structures, columns, crossbars, etc. With too little water, the density of concrete is high and its ductility is low. It is used as a basis for equipment, blind area around the house , etc.
There is one mistake that is often made when mixing the solution. In artisanal production, an excessive amount of water is often added, which reduces the density of concrete and increases its mobility. This in turn significantly reduces its strength.
For concrete, there is its own classification, which is carried out according to the purpose, types of aggregates and binders, hardening conditions and its structure. According to the purpose, it is possible to distinguish ordinary (for civil and industrial buildings) and special (road construction, thermal insulation, hydraulic engineering and decoration works) concrete.
By type of binder, it can be gypsum, silicate, cement, slag-alkali (asphalt concrete, plasto-or polymer concrete). The types of its fillers are also different: porous, dense and special, and its content is lean, greasy and marketable. Also, in its structure, concrete can be dense, porous, cellular and large-pore. Hardening conditions are distinguished by the following: natural, heat-moisture treatment at atmospheric or autoclave pressure.
The main indicator in the characteristic of concrete is its compressive strength. It defines the class of concrete. For example, concrete density B25. This means that in 95% of cases, this class will withstand a pressure of 25 MPa. That is, the letter "B" and the numbers show the pressure that concrete can withstand in megapascals. When calculating the strength index, it is required to take into account the coefficients of the standard compressive strength. It suits the density of concrete B25. The age of concrete, based on its class, will be determined by the compressive strength and axial tension, which is assigned at the design stage. Possible methods of construction and design loads on the structure, as well as conditions for hardening concrete, are taken into account.
Density of concrete B 25 is ideal for floor slabs, monolithic foundations, pool bowls. This is the most commonly used material for these purposes. In addition, builders use such material for other structures of critical designation. The density of concrete B 25 allows us to guarantee the excellent quality of the finished structures, provided, of course, that the purchased goods fully comply with the declared characteristics.