What is this material and how is it produced?
Hydrate lime( powder) is an extremely fine powder of white color, obtained by quenching lime, which initially is a messy clod, which usually occurs in factories with the help of a small amount of water. When it turns out slaked lime, pushenka, its volume increases by about two times. The bulk density of the material obtained is 400 kg / m³, and the moisture content is no more than 5%.
Extinguishing is produced both during the construction of the facility and centrally. With centralized quenching, it is combined with wet grinding of outstanding particles, this process leads to improved quality and increased yield.
During construction, lime is usually quenched in special installations, such a device is called a hydrator for lime. There is loaded lime in a volume of 1/3 of the height of the box( the average thickness of the layer is equal to 100 mm), since during the quenching the volume increases twofold.
Another quicklime, lozenge, is filled immediately with a sufficiently large volume of water, as it is quenched very quickly, so that the raw material does not overheat and the water does not boil. But if the mixture is extinguished slowly, water is added in small portions and it is observed that lime, on the contrary, does not cool.
Depending on the quality of the lime, an average of 2 liters of of the lime test is obtained from one kilogram. This indicator is called the "exit test."Thus, hydrated lime is the only astringent that can be turned into a powder, not only by grinding, but also by quenching with water.
What is responsible for the properties of the pushonka?
The large specific surface area of Ca( OH) 2 particles and their hydrophilicity determine the water-holding capacity and good ductility of the dough. After the slaked mixture has settled, it already contains about half the mass of solid particles and half of the water. Each of the particles is surrounded by a layer of adsorbed water, which plays the role of a kind of lubricant, which provides increased plasticity of any mixtures in which our object of discussion is used.
After the quenching process has been completed, the liquid mixture of calcareous dough is dumped in a day after storage in a storage facility in which it is maintained until the quenching process is finally terminated. This usually takes about two weeks.
The dough, which contains the outstanding grains of not more than half a millimeter in size, can be used freely in the work. But large grains are dangerous because they can include so-called "burnt"( burned grains).Water in its content in the calcareous test is usually not standardized, most often in a properly prepared test it is in equal quantities with the main product.
What nuances of storage and operation can be noted for the pussy?
It has already been said that the calcareous dough has in its composition a saturated aqueous solution of Ca( OH) 2 and small particles of insoluble semifinished product. When water evaporates from the solution, it becomes supersaturated, crystals drop out of it, which increases the content of the solidified mass.
During this reaction, shrinkage of the hardening system occurs, which under certain conditions( this can be solidification of the mixture on a solid substrate, the so-called plaster layer) may well cause cracking of the material. It is for this reason that lime is used with various aggregates, for example, with lime-sand mortar, or by mixing with other astringents to give plasticity to the material.
That lime dough, which is protected from drying, can retain its plasticity for a long time, "setting processes" are absent in themselves. But if the dough still solidified, then it can simply be moistened with water to restore its plasticity. After all, lime is not waterproof.
But with a long process of solidification( dozens of years), lime is able to acquire a fairly powerful density and even a small water resistance. This is due to the fact that in the open air it reacts with carbon dioxide, as a result of which is formed not dissolving in water and quite strong calcium carbonate, the material "again becomes" limestone. But this is a very long process, and as a result of complete carbonization, it still does not happen.
This is an interesting material in all senses is lime-pushenka, its application is very diverse. Air lime is used to make plaster or masonry mortars as an independent binder or as a mixture with cement. You can also notice its use for the production of silicate bricks or silicate products. Not without this material and manufacturers of paints.