Construction without cement is impossible. We will tell, from what raw materials and how important and necessary material is manufactured.
All about components and methods of cement production
Component composition and characteristicsVarieties of binder
Three ways of manufacture
- Dry
- Wet
- Combined
What is cement
The material is used very wide. It is used as an independent product and administered into solutions. All this is due to the properties of the dry mix - it can become plastic when the water is added, and after a while, we will harden, turning into a semblance of stone. Its characteristics are somewhat varied depending on the composition, so it is important to know from which cement is made.
It always has five major ingredients. We will analyze them on the example of Portland cement, one of the most sought-after varieties:
- calcium oxide - no less than 61%;
- silicon dioxide - at least 20%;
- alive about 4%;
- Iron oxide - no less than 2%;
- Magnesium oxide - at least 1%.
Additives that improve certain characteristics of the material are introduced into the mixture. Different breeds can be used as raw materials. Production is usually placed in the immediate vicinity of deposits.
Required minerals are extracted in the open way, this is:
- Carbonate rocks: Dolomite, Mergel, Riseline, chalk and other limestone.
- Clay breeds: Less, Suglinka, shale.
As additives are used apatites, a flood spat, silica, alumina, etc.
Varieties of material
Many varieties of cement comes on sale. They differ from each other by a number of characteristics:
- Strength. The most important indicator that is indicated on the labeling. It is performed in the form of the letter M and numbers. Last and denotes strength. It is determined as a result of technical testing.
- Fraction. Determined by a mixture with a stamp. What he is thinner, the more qualitative products are considered. The ideal is the composition of large and small particles, since only a thin grinding requires too much water during the kneading.
- Highway speed. Varies by introducing gypsum into a mixture. Depending on the purpose of the product, it can differ significantly.
- Frost resistance. Determined by the reaction to the freezing and defrost cycle. The material is characterized by the number of such cycles that it can withstand without changing its properties.
The need for water when the solution is kneading depends on the density of the material, so the amount of water for the kneading of different stamps varies. Excess fluid reduces cement strength.
Depending on the scope of application, several types of cement mixtures are distinguished.
Portland cement
Holds in air and in water. Mineral supplements are absent. Widely used to erect diverse monolithic structures.Sulfate resistant
Its feature is increased resistance to chemical aggressive environments. It is characterized by a low saturation coefficient. This allows the use of sulphate-resistant cement to build hydrotechnical, underground structures, etc.
Pozzolan
It can be considered a variety of sulphate-resistant, but with the addition of active minerals. Slowly hardened, has a high water resistance. Used for hydraulic construction.Aluminous
Increased content of calcium and alumina. This allows the mixture to harden quickly. It is used for the manufacture of rapidly hardening heat-resistant and building solutions that are used in repair work, high-speed construction, winter concreting, etc.
Acid-resistant
The composition includes quartz sand and sodium siliconfluoride. It is not mixed with water, but with liquid glass. Used to obtain acid-resistant coatings. It does not withstand the constant exposure to water.Plasticized
It is manufactured with special additives that give frost resistance and increased mobility prepared on this cement with solutions. They acquire greater strength, better resist the corrosive effects and differ in high water resistance.
Shagocotzer
Slag turns on to his recipe, the percentage of which the content of which can vary from 20% to 80% of the mass of the product. It reduces the mixture, slows down the speed of its curing and increases the heat resistance. It is used to erect terrestrial, underwater and underground objects.
As practice shows, Portland cement is the most sought-after option. It is he who mean when it comes to cement.
How to make cement
Manufacturing technology is to obtain and subsequent grinding clinker. So called granules, which are an intermediate product of production. Their composition is always unchanged. This is a limestone and clay, mixed in a 3: 1 proportion. In nature, there is a mineral, fully identical to the wedge. He is called Mergel. However, its reserves are limited and cannot provide the need for production.
Therefore, the factories use an artificial analogue of Mergel. To obtain it, the necessary ingredients are carefully mixed in large containers with special drums. The mass prepared in this way is fed into the furnace, where it burns around four hours. The temperature of the process is about 1500 ° C. In such conditions, the powder begins to rush into small granules. After cooled, clinker grains are sent to grinding. They are crushed in large drums with balls with balls. At this stage it is important to grind the granules and get a powder product of certain sizes. The grinding is determined by the sieve cell sizes. The resulting powder is mixed with the necessary additives that determine the brand and product properties.
Finished cement materials are stored or to the packaging section, where they are distributed to the container of different capacity or loaded into special cement cars.
Despite the general technology, three methods can be used to produce the composition depending on the properties of raw materials.
Dry fashion
This method can significantly reduce the time and cost of manufacturing the cement mixture. He suggests several stages:
- The raw material is crushed to obtain grains in a small fraction.
- Prepared granules are dried to achieve the desired humidity. This is done to facilitate subsequent operations.
- The ingredients are mixed in certain proportions. After that, crushed, getting flour.
- Powder is supplied to the rotating furnace, where it is burned, but does not sin in the granules.
After cooling, the finished product is sent to the warehouse or on the packing site.
A dry method is considered the least energy consumption, and therefore it is very profitable for manufacturers. Unfortunately, it is not applicable for all categories of raw materials.
Wet method
In some cases, it is necessary to moisturize the material prepared for the production. In such cases, a wet method is used. To prepare a clinker, which consists of limestone and clay, a mixture of the main components with the addition of water is mixed. As a result, a viscous mass is obtained, which is called sludge.
It is laid in the oven where the firing occurs. In this process, granules are formed from the sludge, which are sent to grinding after cooling.
The powder obtained from the clinker is mixed with grinding additives. Only after that the product is ready for packaging and storage. The composition produced by such technology has the highest cost.
Combined method
It is used to reduce the cost of finished products. It is a kind of symbiosis of dry and wet technology. It is initially mixed by the sludge, which is subsequently dehydrated. Thus make clinker. It enters the oven working on the "dry" technology. Next, if necessary, mixing with fillers, and the product is ready. The process is shown in more detail on the video.
The quality of cement largely depends on the raw material from which it is manufactured, and the accuracy of compliance with all technological stages. Given that the characteristics of the construction materials made from it are determined by the quality of the mixture, it is worth paying close attention to it.