Lime is one of the materials that is often used in construction, as well as in a number of other areas. In this article we will talk about this material, explain its properties, types, give a definition, and also explain where it is used, how to dilute it, and also how to apply it in each specific case..
What it is?
Lime is an astringent material that is obtained as a result of burning, as well as the subsequent transformation of limestone, chalk, and other magnesian-calcareous rocks. If we talk about the properties of pure, real lime, then it is a colorless product that is extremely difficult to dissolve in water. This word usually means quicklime and the product of its interaction with liquid..
It should be noted that this material can be in several forms. – with hammer, powder, and also in the form of dough. Speaking about the formula of this material, it looks like CaO. Lime is the result of the burning of rocks, when calcium oxide is the main component of the chemical plan. It interacts quite well with moisture. As a result of the hydration process, we get slaked lime.
Quicklime is a white substance that has a crystalline structure. The proportion of impurities of various types – dolomite, limestone, as well as other minerals of the magnesium-calcium type cannot exceed 6-8%. It is made in accordance with GOST under the number 9179-77, which is called “Building lime. Technical conditions “. Such lime is created from carbonate-type rocks, using various additives that are of a mineral nature: electrothermophosphoric or blast-furnace type slags or quartz sand. According to the requirements of GOST, lime must be crushed in such a way that the residue after passing through a strainer numbered 02 and 008 is no more than 1.5 and 15%, respectively..
Quicklime is classified in the second group of hazard. If we are talking about pure air-type lime, then it can be of both the first and second, as well as the third type. If we talk about lime with impurities, then this is only the first and second grade. And if we are talking about hydrated lime, then this is also only the first and second grade.
Lime gains characteristics of a hydraulic nature due to the presence of silicates in it. From how many of them there are, it can be divided into hydraulic or air. The first category has the ability to improve the hardening processes and the strength of solutions in both air and water. If you look at the content of clinker materials, then lime can be highly hydraulic or weakly hydraulic..
Note that air lime is intended to ensure the hardening of the mortars used in construction, and also so that they retain their strength when the humidity level is at a normal level..
If we talk about the types of lime, then it should be noted that it is divided into different categories depending on the criterion that we take as the basis for the classification..
If you look at the types of lime by the type of processing, then it can be:
- Komkova. It is also called a boiling pot..
- Fluffy. This is, in fact, slaked lime, which is obtained after the lumps have been quenched with liquid..
- Lime-type milk in the form of a white suspension.
- Lime test. This is the result of slaking lumpy raw materials.
- Ground in powder form. It is usually obtained by crushing the burnt lumps..
If we talk about the content of the oxide level, then lime is:
- calcium based.
In the case of calcium, the amount of its content can be from 70 to 95 percent. In magnesia, the content of magnesium oxide is usually from 5 to 20%, and in dolomite – from 20 to 40%.
If we take the slaking rate as a basis, then lime is divided into:
- Extinguishing quickly. As a rule, the indicator is no more than eight minutes.
- Medium blanking rate. We are talking about a time period of no more than 25 minutes.
- Long extinguished. Such lime is slaked for more than 25 minutes..
If we take as a basis the criterion of the technical parameters of burning various rocks, then lumps of lime are obtained with various degrees of strength:
- softly burnt;
- firmly burnt, that is, burnt;
- medium degree of fired, that is, burnt.
In addition, it is also divided according to its chemical composition. We are talking about the ratio of calcium aluminoferrites, as well as silicates.
- Hydraulic. This option makes it possible to harden solutions that are used both in water and simply in an open area..
- Air. This option makes it possible for various solutions and mixtures for construction purposes to harden in cases where there is normal humidity. It should be noted that the composition of the air lime is such that the percentage of the substances mentioned above is 5-15%, and in rare cases it can be 20 percent. There is also a weakly hydraulic lime, which has from 25 to 40% of the content of so-called clinker materials. If we talk about the highly hydraulic type, then it is characterized by the fact that it contains the indicated alumoferrites and silicates from 40 to 90%.
What are they made of?
For lime, the brand and type will be the determining factors, which determine the main segment of its use..
If we are talking about lime for construction work, then this type, as a rule, consists of rocks, which contain a very high percentage of calcium, as well as magnesium. This type is used as a plasticizer for various kinds of binding solutions, as well as for concrete mixtures. This brand is usually sold in the form of lumps and fluff or lime dough..
Typically, this type of production requires:
- rocks of the carbonate plan;
- various mineral-based additives, which include active mineral additives, as well as quartz-based sands and electrothermophosphoric or blast-furnace slags in granules.
If we need a hydraulic mixture, then it is released from limestone, which contains up to 20% clay impurities. They make it by firing. It should be noted that this type is usually made for the production of low grade concrete. It’s just that its ductility is extremely low, and its strength is very high. This type of lime is usually used to create structures that will be used in conditions of high or high humidity..
The lumpy type is usually used as a kind of semi-finished material to create various solutions and powders. This type is usually stored in closed warehouses so that moisture does not have a destructive effect on it..
During rainy periods in spring and autumn, quicklime or slaked lime is sometimes added to the soil. By the way, the latter, upon contact with water, releases alkali. Limestone dissolves better thanks to precipitation.
There is also a so-called soda variety.. It is a combination of slaked lime and caustic soda. Usually used in the creation of pressure chambers, gas masks, as well as various diving equipment.
There is also a chlorine variety. It consists of calcium hydroxide as well as free chlorine. It has excellent whitening properties and is a powerful antiseptic.
Different categories of lime have different shelf life. For example, if you take quicklime, it should be stored for about two weeks in a room that will be extremely unheated, dry and closed. If it is possible to store it in a production environment, then it is better to do this in special containers that have a feeding system.
If such a product is stored in sealed packaging, then its shelf life is unlimited.. Here it must be said that the storage of this type of lime must completely exclude the ingress of any liquid on it, otherwise it can cause a very strong heating of the substance.
After dehydration has been carried out, lime must be kept in a specially created pit for about a crescent in case it will be used for masonry or to create some kind of solutions. If it will be used for plastering, then it should be stored for about a month..
After that, a 20-centimeter layer of fine sand is usually poured onto the solution. If the outside temperature is below freezing, in order to exclude the possibility of freezing, you can pour a 70-centimeter layer of earth on the sand. Also, a pit with lime should be fenced off and marked so that everyone around them knows about its presence and animals cannot get on it. As a rule, in the consistency of the dough, such lime is stored for quite a long time. And the more time passes, the more quality it becomes..
Bleach is usually stored exclusively in sealed packs in a place that is completely protected from moisture and ultraviolet rays.. The packaging must be marked with a label that indicates that the substance is corrosive. It is packed in polypropylene or polyethylene bags, as well as in steel drums with polyethylene liners. On the market, these will be packages weighing 0.5, 1.2 and 1.5 kilograms. The pack can be sealed, or it can be tied with a metal ring or chlorine-resistant twine.
If we talk about the severity of human exposure, then substances such as lime are included in the group of moderately hazardous products of the third group, and the chlorine that is released belongs to the second group..
Decomposition of chlorine-based lime results in the evolution of oxygen and chlorine. But this is possible only under the influence of natural factors. It is a strong oxidizing agent, and chlorine dust can irritate the mucous membrane..
When working with such a substance, the respiratory system and eyes should be protected with special equipment. – a respirator or a filter-type gas mask. Packages of this type can be stored in warehouses with a high-quality ventilation system, which are unheated and protect lime from UV rays. The floors must be made of brick, concrete or asphalt. In a room with such substances, it is impossible to store gas cylinders, flammable, as well as various explosives. The storage period in warehouses can be either a year or three years.
By the way, storage facilities must be equipped with fire extinguishing devices: acid-based fire extinguishers, cranes with fire hoses, boxes filled with sand, and so on..
Scope of application
For a long time, lime was used to make lime cement. Despite the fact that it freezes perfectly in air, it absorbs a large amount of moisture, which causes fungus to appear on the walls. For this reason, it is no longer used in this capacity. Such lime will also be a component of various materials for plastering, creating dyes, silicate-based bricks, cinder concrete, and so on..
It is also actively used in horticulture and agriculture.. For example, bleaching lime is an excellent material for treating trees and plants from various rodents and pests, fertilizing soils with acidic properties, as well as whitewashing. Milled limestone, which has the same properties as chalk, is used as a raw material in the creation of feed for livestock, as well as feeding for poultry.
The use of quicklime makes it possible to neutralize waste water as well as flue gases. In addition, with its help, various types of surfaces are painted – walls, technical rooms..
Lime is often used in food processing industries. For example, it is found in a number of products as an emulsifier with the designation E-529. In addition, it is needed by any area where it is necessary to mix substances that cannot be mixed due to their nature – for example, water and oil..
Lime has gained popularity for the following reasons:
- low cost;
- excellent disinfection properties;
- resistance to moisture ingress;
- lack of any unpleasant odor;
- good compatibility with dyes;
- UV resistance.
But she also has a couple of disadvantages:
- very caustic in work, which requires caution;
- bubbles, streaks and streaks may appear if the solution was not prepared correctly.
How to breed?
This process is messy and time consuming. Cover floors and furniture with foil and wear protective clothing prior to work. If you decide to whitewash the room, then the consumption will vary depending on the method of application, as well as on the surface area that is being processed. If whitewashing is applied using a brush, then its consumption will increase significantly.
In addition, it all depends on which lime you choose.. For example, quicklime dry lime is poured in a one-to-one ratio. By pouring three liters of water for one part of lime, you can get a lime-type dough. And after that, the lime can be diluted with liquid..
From one kilogram of quicklime, it is easy to get 10 liters of whitewash, ready to use. In some cases, gypsum and sand can be used to dilute lime, but only to improve its properties..
It will depend on where exactly the mixture will be used. To whitewash a room, you need 0.5 liters of finished whitewash per square meter. If we are talking about fluff, then from a two-kilogram pack you can get six liters of whitewash, which will be enough to whitewash about 12 square meters of the surface. True, if you have to work with brickwork, then you will need more.
If we talk about the finished lime dough, then its ratio will be such that three liters of liquid are required per kilogram of dough.
If we are talking about quicklime, then first it must be extinguished, and only then diluted with water. In the case of her, from one kilogram of quicklime, you can get about ten liters of whitewash, ready to use..
Rooms are whitened with a spray gun, spray or brush. A roller is never used for whitewashing, because if you roll out the whitewash with a roller, but already the second layer, then the first layer simply will not withstand the load and will move away from the surface. Usually a special brush is used for whitewashing. Soak it in warm water for several hours before use..
Brick walls can be treated with a simple bristle brush that has natural bristles. By the way, if everything is done with a brush, then there will be stripes. In order to remove them, a second whitewash layer should be applied in the direction of the light flow..
It will be best to whitewash using a spray gun. It will lie flat, and the consumption of lime will be significantly less.
If we talk about the very algorithm of work, then first you need to close all windows, doors and furniture with foil. You can greatly facilitate the work when you need to clean the rooms. After that, you should prepare the surface for the process, namely, remove the old layer, remove stains, as well as whitewash, which is already peeling. Also, it will not be superfluous to close up the cracks..
Now you should dilute the whitewash. If the process is carried out using a sprayer or spray gun, then the mixture should first be filtered. Stir the solution before adding the next portion of lime to the device..
Before working with the equipment, you must familiarize yourself with the rules that the technological instruction contains. Before applying whitewash, you should slightly wet the surface using a spray. Now the whitewash must be poured into the spray gun and air is pumped in. Now we adjust the spray nozzle so that the whitewash is sprayed as evenly as possible. If spraying does not occur, it is too thick..
Then you need to add liquid there and stir it. The sprayer should be 15-20 centimeters from the surface. The process should take place exclusively with the help of circular movements. After a couple of hours, the second whitewashing layer should be applied on the first layer, which has not yet dried out..
Tips & Tricks
If you are storing lime in bags, it is best to store it in a dry place out of the sun. When purchasing this substance, make sure that it is stored in suitable conditions, a description of which must be included on the package. In addition, lime whitewashing is quite cheap and would be a great solution on a limited budget. Another important point – lime whitewash will be an excellent solution for wet rooms, as it has excellent moisture resistant properties..
Before applying a new whitewash, you should first wash the old whitewash from the ceiling. In any other case, the new whitewash will simply fall off along with the old.
You should also be very careful to dissolve lime in water.. Given the differences between the different species from each other, the amount of water that is needed will be different. Boiling lime, sodium or carbonic acid will require different amounts of water for proper dilution..
To give the whitewash some pleasant shade, you can add color to it. Usually, in this case, 20 g of blue is added to the container with whitewash. For carrying out various kinds of finishing work at a house made of wood or brick, it would be best to choose a cloudy day or evening. The reason is simple. The characteristic of lime is that it does not like too dry and hot weather, as well as exposure to direct sunlight..
The technological procedure for applying whitewash should be followed as much as possible. Any deviation from the process will cause the result to disappoint you..
Lime is an excellent material that has many uses.. For example, white lime traditionally decorates trees since spring, protecting them from pests, serves as an excellent solution for whitewashing walls and generally has a lot of advantages that distinguish this fairly affordable material from others..
For information on how to properly extinguish lime, see the next video.