Among the varieties of particularly heavy concrete there is a so-called barite concrete, which consists of a mineral binder (cement) and water, and as a filler there is barite ore, which may have a different fraction (sand or gravel). In addition, the filler can be mixed with cast iron shot or secondary metal (metal waste - scrap).
Below we will talk in more detail about this material, methods of its manufacture and use in construction, and in addition, we will see a demonstration of a thematic video in this article on the same topic.
Scope of application
Protective agent in medical technology
- Depending on the bulk density, all concrete based on cement can be divided into particularly light - less than 500 kg / m3, light - from 500 kg / m3 up to 1800 kg / m3heavy - from 1800 kg / m3 up to 2500 kg / m3 and especially heavy - more than 2500 kg / m3. The latter option is usually intended for the construction of various structures of protective type, which prevent the penetration of radioactive radiation.
- At present (UN data), after a natural radioactive background, radiation takes the following place in medical (therapeutic and preventive) purposes, and not in a single country, but, in general, on the Globe. According to statistics, 2.8 mEb is accounted for per person on the planet, where medicine accounts for 14%, while in Russia these figures are 3.3 mEb and 31.2%, respectively. (See also the article Decorative concrete: features.)
- Without equipment, which radiates a radioactive background, it is already impossible to do in medicine today and it certainly brings tremendous benefits in diagnostics and therapeutic treatment.. But there is also a downside to the medal - this is a harmful effect on the organism of patients, medical staff, and even unauthorized people who happened to be within their grasp. X-ray (ionizing) radiation can be the cause of radiation sickness, burns, malignant tumors, and also cause mutations of living organisms.
- Therefore, it is quite natural that the instruction SanPiN (sanitary rules and regulations) provides not only personal protective equipment and shielding of devices, but also the use of special building materials that can form a protective coating. For example, such regulatory documents provide for a certain calculation of the level of protection (layer thickness) for the floor, ceiling and walls of treatment rooms of this type. In these cases, the use of building materials with a high degree of radiation protection (RH) is most acceptable.
Примечание. Наиболее известная РЗ, это свинцовые листы, но для этой цели применимы разные элементы с высоким атомным номером, к которым, собственно, и относится барит - BaSO4 (греческое значение слова «барис» - тяжёлый). Это природный сульфат бария, тяжёлый шпат, содержащий в себе 65,7% BaO и 34,3% SO4. Кроме того, там могут присутствовать различные примеси, такие как кальций, стронций и свинец.
- At the end of the 80s of the 20th century, the All-Russian Research Institute of Medical Equipment and Equipment developed lead-free PES based on rare-earth oxides (waste of Minatom enterprises). Advantages of BaSO4 before lead, it is rather obvious - it is harmless, whereas materials containing lead are toxic and, moreover, are subject to rapid aging. (See also the article Hydraulic concrete: features.)
Note. As we have already said, baritone concrete is a very heavy material, because approximately 80% of its composition is occupied by Ba SO4, therefore, it cannot be used on soils with insufficient bearing capacity (subsidence is possible).
When pouring and molding concrete and reinforced concrete products using barite as a filler, one should take into account that you expect a sufficiently large shrinkage rate (this phenomenon leads to a decrease in reinforced concrete construction as a result of setting, drying and hardening).
For monolithic solution with BaSO4 poured into the right place for molding (formwork, casting mold), after which it begins processing by vibration, which allows you to get rid of pores (air bubbles), which will certainly remain in the process of laying the mixture. To do this, use either vibrating tables or portable vibration devices, this process, as well as its own weight of the solution contributes to a high percentage of shrinkage.
Baritобетон (ББ) используется не только в качестве радиоактивной защиты, но и как материал с повышенной химической стойкостью для сооружения различных промышленных объектов. Учитывая тот фактор, что цена ББ довольно высока и, к тому же, такие конструкции имеют узкую специализацию в применении, данный материал в наши дни не получил широкого распространения.
However, due to the high quality of the structures they possess for radioactive and chemical protection, the use of BBs tightly occupied its own niche in the design and construction of special-purpose structures.
Of course, BB can withstand the effects of various aggressive chemical elements (alkalis, acids) and radiation, but for this there are alternative methods using other materials. But, despite the high cost and lack of popularity, there are areas where it is almost impossible to carry out construction and installation works without its use.
The most important characteristics in determining the quality of BB are a few parameters that we consider in more detail. First of all, from such a monolithic or composite structure, the maximum level of radiation absorption is achieved. This is perhaps the main criterion by which the necessity of using BB at specialized industrial or defense construction objects is determined.
Thus, the presence of metal scrap in the composition of the filler of barite concrete contributes to one hundred percent retention of alpha and beta radiation particles.
Gamma radiation is also absorbed by such material, but there are already some number of coefficients that can be used to calculate the sufficient thickness of the barrier to reduce the radiation background to a level safe for the life and health of the staff, that is, to make it natural for the human body.
It is almost impossible to overestimate the effectiveness of BB in the construction of bunkers - such building materials in this area can be called indispensable for creating the appropriate conditions for normal life and people there. In addition to human and human equipment, such a bunker will have high strength characteristics, since it is built from a BB, belonging to the class of especially heavy concrete.
As in the manufacture of conventional heavy reinforced concrete structures, for barite concrete reinforcing metal frames are used, making the material even stronger mechanically. At the same time, the requirements for both prefabricated and monolithic structures remain unchanged - the metal should be covered with a solution layer of not less than 50 mm.
You can also create a radiation protective layer in a room with your own hands, using the necessary mixtures for mixing it with water - the proportions and preparation time are indicated by the manufacturer.
If you want to equip a private office, then you should have for this project documentation, compiled according to SNiP 3.04.01-87, which determines the desired thickness. When creating a monolithic reinforced concrete structures are guided by GOST 52085-2003.
Anyway - are precast reinforced concrete structures used or made monolith directly on the construction site using BaSO4 - there will be used cement as a binder. Given the high cost of the material being created and its special purpose, only high grades of fresh and high-quality cement are used there.