In construction works, cement is consumed as an independent raw material, and as a component in the composition (concrete or reinforced concrete). The manufacturing process is time-consuming and expensive. The technologies used by manufacturers directly affect the quality of raw materials and their final cost.
The basic composition of cement is the same for all types. Cement is made from the clay rock from which clinker is made. Technical specifications depend on the type of processing. About 15% of the composition is made up of mineral additives (only in the exact ratio with the established state standards). If the percentage of additives is broken, the properties of the cement mortar will be changed. The solution has a name-pozzolan cement.
The quality of the material is directly affected by its production technology:
- the granularity of grinding affects the degree of solidification of concrete and its strength. The smaller the grinding size, the stronger the solution.;
- to increase the plasticity of the cement mixture, plasticizing components of organic and inorganic origin are added to it;
- the level of heat release is also affected by the additives used. Special substances can affect the amount and rate of heat release.
Today, manufacturers offer consumers many types of cement, which should be used depending on the working conditions and structural features. But production technologies remain standard.
Stages of cement production
Cement production should be divided into two main stages: obtaining clinker and grinding the components. Clinker is a natural mixture, usually made from lime (about 75%) and clay (about 25%). The components were fired in special furnaces under the influence of high temperature. It is possible to replace clay with other components of natural origin, for example, trepel or dolomite.
In nature, you can find ready-made clinker that does not need to be fired. This is marl-a rock. But there is so little material in nature that manufacturers prefer artificially made clinker.
The second stage consists in thoroughly mixing the clinker components in special containers. Then the mixture is fired for a long time in furnaces, which allows the components to interact with each other. As a result, the clay and lime form small balls, the size of walnuts. Then the components are mixed and ground again.
Cement production technology
The technology of cement production has its own characteristics, depending on the method: wet, dry or combined.
Dry cement production technology
This method is cost-effective, so it is used in almost every production. Its special feature is that the components remain dry at every stage of operation. The basis of material production is based on the chemical and physical characteristics of the raw material used.
All elements are additionally dried and then ground to a powdery state. The components are combined, in other words, they go through the stage of homogenization. The result is homogenized silage or flour. Then the raw flour is sent to the oven for delicate roasting. The resulting mixture is called clinker.
In the next mill, various additives are added to the clinker (depending on the type of cement). Then the components are crushed and mixed again. After that, the raw materials are sent for storage in the hopper. There, cement is packed in bags of various capacities and sent for shipment.
Wet cement production technology
Creating a cement mixture with the addition of liquid is a less popular method compared to the previous one. Carbonate chalk and Silicate clay are used in its production. It is possible to use iron-containing additives, for example, converter sludge, pyrite residues.
The clay that is planned to be used is processed in special roller crushing systems, crushed to a granule size from 0 to 100 mm. The composition is sent to the chatterboxes for further soaking. This allows you to create sludge with a humidity level of about 70%. The components that make up the mixture are mixed and ground using a given percentage of moisture. In the end, a charge is obtained with a humidity level in the range of 30-50%.
At this stage, the mixture passes quality control. If its indicators meet the standards, it is fired under the influence of high temperatures, which turns into miniature grains. They should also be ground to a powdery appearance. This technology is labor-intensive, so it is used in the formation of some solutions.
Combined cement
This technology combines two methods of cement production at once. In the grinding drum, the sludge passes the stage of forced moistening up to 40-45%. Then the composition passes through filters for its dehydration. Then the composition is delivered for warming up, which further reduces the liquid content.
After that, the cement mass is sent for warming up, where it is constantly mixed. The finished product is sent for safekeeping and for further packaging in bags.
Production of white cement mortar
The production of white cement requires separate consideration. The material is widely used for surface treatment. After drying, it becomes white.
The mix compounds include marl, limestone, marble, sand, and clay, but to a lesser extent compared to gray cement. Most of the mixture is made up of marble chips. The mixture also allows the presence of coloring oxidizing elements: iron, chromium, manganese, titanium and others. Chalk and kaolin give a white tint to the solution. High requirements are imposed on the purity of the water used, its percentage in the total mass is not more than 45%. The material goes through several levels of cleaning, so it ends up with high-quality cement. The surface treated with a solution of white cement has no flaws.
Clinker grinding continues in the Mill unit, in which a specific lining is installed. The delicacy of grinding white cement is much higher than that of ordinary gray cement. Therefore, the mixture is produced in two grades M400 and M500. Products made of white cement do not crumble, do not collapse, they are easy to care for. Therefore, the material is used in creating a variety of architectural buildings and forms.
The white color of the material allows you to create other shades. At the final stage of production, a certain percentage of pigment additives is added to the mixture.
For each type of cement, special equipment is used, and manufacturers adhere to a certain sequence of actions. Therefore, it is recommended to purchase cement from manufacturers who have already established themselves in the construction market and accompany their products with quality certificates.