As it is impossible to imagine a good porridge without butter, and high-quality mortar without lime. It’s a common binder finds wide application in construction. Lime is produced by calcination of sedimentary rocks, the main component of which is calcium carbonate and perhaps magnesium oxide, When the content of magnesium oxide more than 7% of lime is called magnesia, with a smaller it presence of calcium. In the construction using both lime. These rocks are tight, clean and dolomitized limestone, chalk, shell limestone and other Rocks should not contain more than 8% clay impurities (the fewer the better and cleaner lime). Roasting is performed at a temperature of 900° — 1200°C up to possible the complete removal of carbon dioxide, that is, the decomposition of calcium carbonate with the release of carbon dioxide and formation of calcium oxide or so-called lime-quicklime.
With high quality raw materials and complete removal of carbon dioxide from 100 parts by weight of pure limestone should be 56 parts by weight of lime-quicklime and 44 weight parts of carbon dioxide, or carbon dioxide, which will be further required to hardening of mortar, but is absorbed from the air.
Calcined limestone, or lime-quicklime. is a porous relatively lightweight stone volume weight 1000 — 1400 kg/m3 . Was the purer the limestone, the easier the lime-killka, the higher its quality. Thus, depending on the quality of the limestone turns the lime three varieties, with different timing of extinction.
Not lit, but is extinguished
Usually the beginning of the blanking is determined by the time of the first cracks in the pieces of lime-quicklime, previously saturated with water. In settings this can be done in the following way.
To break away from three different pieces of lime-quicklime in small pieces, put them in water for three minutes, remove, put on Board, notice the time. As soon as the first crack — this is the time to start blanking.
According to these indicators, the lime-kipaka is divided into bystrogasjashchajasja (from 8 to 25 minutes) and gasesous slowly (over 25 minutes). Incorrect definition of this indicator leads to incomplete release of lime and lower quality.
In the production of lime from raw materials can result in incomplete combustion and burnout of the First is harmless, as water or solutions it is not extinguished. Dangerous burnout — then the pieces of lime extinguished very slowly. Particles of burnt lime, not in time to each other and used in the solution, continue to be suppressed even two or three weeks, but in the plaster. They are quite a long time, sometimes years. forming on the surface of the so-Called ring in the form of delaminations of plaster.
Is afraid of water, but the water loves
Lime-quicklime should be stored in dry warehouses or barns, but not on the floor and in pairs (boxes), raised from the ground not less than on 50 see Better to pack it in heavy paper or plastic bags, firmly close tie, because the lime-cipapku absorbs moisture from the air and may spontaneously begin to extinguished, that is, decaying, and turn into a thin powder called pushonkoj, with a volumetric weight of about 400 — 500 kg/m3 . If the lime is quicklime is exposed to water it begins to rapidly extinguished, while when heating to a temperature of 350°C and above that can lead to fire hazards adjacent to lime wood.
For use it is best to extinguish izvest-kipelku immediately in milk of lime, which, settled, turns into a dough. From the hydrated dough exits smaller, and lower quality.
Slaked lime:
1 — tvorilnuyu pit; 2 — to extinguish; 3 — grid; 4 — valve; 5 development; 6 — paddle-type mixer
Izvest-kipelku should extinguish after receipt as possible in the dough and in the worst case — hydrated. When the lime itself is suppressed in the hydrated from the moisture from the air, it turns into “Palanka”, not with astringent properties.
Hydrated to keep safer, as when in contact with water it gives off far less heat than quicklime.
Lime-cipapku quenched in hydrated. Poured on a wooden Board with a layer up to 20 cm From the sprinkler or hose with spray gun watering it with water, the amount of which is 600 — 700 l per 1 m3 of quicklime. From lack of moisture it turns into a powder-hydrated, which is stored in tightly closed chests or bags. Subsequent addition of water to lime-pushonka turns into a dough.
When slaked lime is quicklime in the putty its first turn in the so-called milk of lime, which as the evaporation of water transferred to the liquid or dense state. For damping of 1 m3 of quicklime in the dough requires 3000 — 4000 l of water.
Equipment — simply nowhere
Depending on the amount of slaked lime-quicklime in the dough this operation can be performed in barrels, troughs or other containers, and the best — in specially made to extinguish the box. Long-term storage of the limy test should be carried out in tvorilnoy pit (Hod) dug in the ground and covered with planks on the walls and floor. Covered up first with sand and then a layer of soil thickness of 50— 70 cm or more, the dough can be stored for years without access of air, acquiring special binding properties. This is evidenced by the quality of plaster, made hundreds of years ago solutions on a well-aged lime test.
To prepare the plaster for 1 volume part of the limy test requires the following number of volume parts of sand: 1 lime-grade — 3 — 4 pieces, 2 varieties — 2,5 — 3 parts and for 3rd grade — 1.5 to 2 parts.
As has been said, to lime slaking of quicklime or hydrated in the dough used to extinguish the box and tvorilnuyu pit. The dimensions of the box (length, width, height) depend on the number tagasivaates lime. It needs to be tight, and the bottom boards are nailed along the length of the box. In the wall facing the pit, leave the window size 25×30 cm, It closes the vertical valve. movable in the slots, and a mesh cell cross-section 3×3 mm. through which the filtered milk of lime is poured into tvorilnuyu pit. The grid with such cells are often clogged with pieces of lime burnout and it has to be clean, and this takes time. Better for the hole to fill the grid with a mesh size of 5×5 mm, and under the hole to mount optional horizontal grid with smaller holes, where you will stay the pieces burned. It is easier to clean (as necessary). Nepogashenija all the bits and pieces should be placed into a separate box and moistened with water: with time, they too will sagaseta.
To extinguish the box is placed at tvorilnuyu pit side with a hole. Tvorilnuyu dig a hole the right size to a maximum depth of 1.75 m (to at random fall of a man there he could not drown). The walls and floor covered with boards of thickness 20 – 25 mm below the limy dough not mixed with earth.
After the slaked lime, milk of lime settling and evaporation of the water will produce a solution containing 50% of the limy test and 50% water (by weight); the volume mass of the dense test is 1300 — 1400 kg/m3 .
The secrets of the technology
Slaked lime given the properties of the original material carry out so. The valve is closed, the crate is loaded with lime-a quicklime or pushonkoj 1/4 of its height. Water in required quantity is about of the box or it summed up the pipeline with water.
Bystrogasjashchajasja lime fill with water to half the height of the box. As soon as it starts blanking (selection couple), water is added, but gradually, so as not to cool the lime (she is very hot, water as it boils, releasing large amounts of vapor). Lime in process of slaking is mixed well with a paddle or bottom until a homogeneous milk of lime. As soon as the slaking is over, that will be seen by the decrease in steam generation, the valve is opened and milk of lime is poured into tvorilnuyu pit.
Srednegasjashchujusja lime download and fill is similar, but half the height of the box. As damping is also gradually in small portions add water. After clearing all is well mixed, adding water until thick milk and poured the solution into tvorilnuyu pit.
Melanogrammus lime is loaded into the box and pour water in several stages. At first it only slightly moistened, and as the damping in the small portions add water, mixing thoroughly to avoid lowering the temperature. Damping it is desirable to produce warmed water, which increases the speed and completeness of slaking lime of any kind, but the box at this time than any cover, so that the lime is not lost heat.
Faster and better absorbed small pieces of lime, so it is recommended to split large. Neglect the above tips helps to reduce the output of slaked lime, and its quality decreases.
Recommended tvorilnuyu pit immediately filled with milk of lime, the mass did not have time to harden. Pour a new batch of lime slurry to thickened the dough is not: accidentally caught nepogashenija particles will sink to the bottom. and if you fall then in the solution, the cause mentioned quilted. For this reason, it is not recommended to use in plaster solutions of the lower layers of the limy test in a short period of its incubation (15 — 18 days). The timing should be extend to 3 — 4 months. If you want to include in deals souhassou lime, it must first be filtered through a sieve with apertures of size at least 1,5×1.5 mm, to withstand another 6 — 7 days with stirring 3 — 4 times a day I. only then drain settled water, the mass can be used.
Determination of fat content of solution on the inclined blade stirrer:
1— lean solution; 2 —normal solution; 3 — oily solution
Emphasize again that the longer aged lime putty in tvorilnuyu pits under a layer of sand and land (so it wouldn’t harden from contact with carbon dioxide of air), the better.
The hardening of the mortar based on lime is due to the absorption of carbon dioxide from the air and evaporation of water from it, which occurs only when the lime has a small moisture content from 2.5% to 5%. In dry plaster, this process is called carbonation, the result is again obtained calcium carbonate, almost insoluble in water. Basically, this process happens only on the surface, thereby creating a dense crust. After carbonization of the hardened mortar on its structure resembles a calcareous Sandstone, but more porous than natural.
Pure lime putty will not harden. Therefore, it is to prepare the solution add sand. Lime mortars unseemly clutch slowly, so assume a large scope of work. To accelerate this process, they add cement or gypsum.
As mentioned above, depending on the grade of lime-quicklime is obtained the dough is different plasticity, or of fat, requiring different amounts of sand. Fat lime putty is at the top and skinny at the bottom (there’s a lot of particles nepogashenija lime). Durable mortar is obtained on the fat test with sand composition 1:3.
When liming should follow the safety rules. It is necessary to work in strong overalls, rubber boots, gloves, protective glasses and respirators.
A. SHEPELEV
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Born of fire. As it is impossible to imagine a good porridge without butter, and high-quality mortar without lime. It’s a common binder finds wide application in construction. Lime is produced by calcination of sedimentary rocks, the main component of which is calcium carbonate and perhaps magnesium oxide, When the content of magnesium oxide more than 7% of lime is called magnesia, with a smaller it presence of calcium. In the construction using both lime. These rocks are tight, clean and dolomitized limestone, chalk, shell limestone and other Rocks should not contain more than 8% clay impurities (the fewer the better and cleaner lime). Roasting is performed at a temperature of 900° — 1200°C up to possible the complete removal of carbon dioxide, that is, the decomposition of calcium carbonate with the release of carbon dioxide and formation of calcium oxide or so-called lime-quicklime.