Concrete – the god of construction
Concrete is a building material that is included in almost all types of structures under construction in housing and industrial, hydraulic engineering, road, bridge, airfield and other types of construction.
BACKGROUND OF THE INVENTION
The history of the invention of concrete is associated with the emergence of cement – a binder. This event dates back to 1824 and is associated with the name of D. Asidno, a builder from the city of Portland. It is this fact that gave the name to this material – Portland cement. During the struggle against cosmopolitanism in the USSR, this invention was attributed to the scientist Egor Cheliev, and the material itself was called silicate cement. This authorship and title did not take root in the future. In its pure form, cement has not found independent use, and its main development is associated with the production of concrete and concrete products. Over the next two hundred years, this material practically did not change its composition.
Cement is a hydraulic binder that hardens when combined with water. Cement is made from 75% limestone and 25% clay by firing in rotary kilns at a temperature of 1450 degrees. Thus, a substance called clinker is obtained, to which about 6% of gypsum is added.
Concrete is obtained by mixing cement, water, sand, gravel or gravel. For example, for the manufacture of one cubic meter of grade 200 concrete, 400-300 kg of cement is required, 180 liters of water, 0.9 cubic meters of crushed stone or gravel, and 0.45 cubic meters of sand. This ratio provides the concrete mix with the necessary processability and mobility. Sand, gravel and gravel are inert materials that do not enter into a chemical reaction with cement and provide the concrete mixture with the appropriate strength and the required structure.
In industrial conditions, the concrete mix is made in concrete mixers with a capacity of 600-1200 liters by thorough mixing of the components. Small mobile concrete mixers manufactured by industry can be used for cottage construction, which is much more economical than the production of concrete mix to order in large enterprises.
The setting time of the concrete mix usually varies from one and a half to four hours, after which thickening sets in. The use of water for liquefying concrete is unacceptable, as it leads to a significant loss of strength. With a small demand, the concrete mix can be made on the so-called “striker” – a board board with continuous mixing of cement, gravel and sand and gradually adding water.
The use of concrete in construction is so widespread that it is an indisputable fact. Due to the introduction of appropriate additives, concrete is also applicable in an aggressive environment, for example, in sea water. Concrete and reinforced concrete is used in all types of industrial, agricultural, mine and civil engineering. With its help, load-bearing and enclosing structures, parts and elements of bridges, fastening of mine workings, pile and sheet piles are erected.
In residential construction, reinforced concrete is used to produce floor slabs, wall and roof structures. In industrial construction – for the manufacture of columns, beams, trusses, foundation blocks and other critical elements.
It is noteworthy that reinforced concrete is used not only in the “standard” environment, but also in shipbuilding. So in the prewar and war years in England reinforced concrete ships of the Liberty type were built, on which cargoes were delivered to the USSR as part of the northern convoys. And today, reinforced concrete landing stages, floating and dry docks, pontoons and even yachts are successfully operated in the marine industry.
PROSPECTS FOR CONCRETE IN CONSTRUCTION
Thanks to the development of modern technologies for the production of concrete and reinforced concrete structures, it becomes possible to use it for the reconstruction of obsolete buildings and structures. For example, it is practiced today in the mining, engineering, metallurgical industries. Concrete is used to replace the old housing stock – five-story post-war houses; construction of modern public buildings – hospitals, hotels, schools and preschool educational institutions, shopping centers and other facilities necessary in each city.