How to choose the right cement for the construction of your home
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Cement is rightfully the dominant position among all modern building materials. Apply it everywhere, almost at all stages of erection of the building. Foundations and concrete roofs, artificial wall blocks and monolithic enclosures, cast on the floor and ready-made slabs, stairs and staircase marches, ties and jumpers, masonry and plaster solutions, tile adhesives, putty, grout, nylmerksy and other dry mixtures – difficult It is practically impossible to build without cement. But, not always he was at the disposal of people.
Our ancestors, several millennia in a row, by trial and error, were looking for a universal binder, but they did not succeed in getting closer to the ideal. Clay, lime, gypsum, practically, immediately fell into the sight of ancient architects, and they are now actively used to prepare solutions for internal work. However, the only problem was that such binders are not able to adequately withstand the effects of moisture.
There were no alternatives for a long time, but at the very beginning of the century, the Romans were able to create a mixture that looks like modern concrete – archaeologists have found and dated the well-preserved, rather solid solid monolithic structures dating back to the first century. And these were not shards and fragments, but serious buildings, for example, the famous Roman drainages. It is believed that the builders of ancient Rome have successfully experimented with volcanic ash, especially noteworthy were the soils in the area of Pozzuoli near Naples, which could be caught even under water. Everything would be wrong, but over time, the technology of producing the pozzolanic binder was irretrievably lost, the alchemists began to invent a magic powder that turned into a stone again.
At the turn of the 18th and 19th centuries, the first cements of the new time appeared. Who should give the palm of superiority to the opening, as usual, difficult to say – everything happened lightning and practically simultaneously. In 1796, James Parker, at 800-900 degrees, shook a mixture of clay with lime and received “romance” (Roman cement). Louis Vek in 1817 published (without patenting technology) his studies of the hydraulic properties of a mixture of lime and volcanic ash, which described in detail the temperatures, ratios, conditions, compositions. 1824 – Joseph Asdin modified the theoretical basis of the predecessors and quickly obtained a patent for “Portland Cement” (some characteristics similar to rocks from the English town of Portland).
In practice, Russian scientist Yegor Gerasimovich Cheliyev claims, in parallel with the Englishman, about his discovery of cement, but the patent has already been issued to the subject of the British Empire, and this innovative binder for a long time gets the name “English cement”. After the Worldwide London Exhibition in 1851, cement is gaining universal recognition, in all developed countries its mass production begins. In 1856, the first cement plant opens in Russia. This construction breakthrough was achieved with the introduction of the derivatives of cement materials – concrete and reinforced concrete, which did not have to wait long, it happened in the middle of the 19th century.
How do cement work
More than two hundred years have passed, but the technology of cement production has not fundamentally changed, except that now more advanced aggregates are used, grinding became thinner, special additives appeared, and precise parameters of control and weight manipulations were established. The process of obtaining cement takes place according to the following scheme:
Raw material (chalk / limestone, clay / loam) after shredding is cut into pieces not more than 10 cm and is mixed – at the output slurry of coarse grinding. Then he will be crushed several times, each time thinner.
The sludge is moistened, or vice versa dried (there are three methods of producing cement – wet, dry and combined). When dry, the sludge is not moisturized to 30-50%, but a dry powder in the oven.
At a temperature of about 1400-1500 ° С, the slime is burned for several hours in a rotating oven until a sintering of elements is uniform “alloy” – a cement clinker in the form of beads.
The clinker is ground / rubbed to powder state.
About 5 percent of the gypsum is added to the powder, which is intended to control the setting speed. At this stage, various ingredients can be introduced into the resulting composition, which improves certain properties or reduces the cost price.
At the final stage, the quality of the whole lot is checked – samples of cement mortar products are made, which are tested in laboratory conditions. On the basis of experimental research, each batch gets its mark on durability.