Repairs

What is the difference between quicklime and quicklime

In the II-III century BC the peoples of the Cretan-Mycenaean civilization used lime plaster without any fillers and additives in the construction of palaces in Mycenae, Knossos, Tiryns and Festa. Nowadays, lime plaster (IS) contains fillers and various modifying additives, giving the compositions new properties. Cement-lime plasters are more common than others.

Features

Lime has long been obtained by roasting sedimentary rocks such as chalk, limestone, limestones, unsuitable for decoration marble, in which there is a lot of calcium carbonate and partially carbonic magnesium (the proportion of which is different in different deposits). Therefore, the quality of lime obtained from different deposits varies. These rocks become calcareous after firing.

Depending on the content of clay in the raw materials, lime can be:

    airy, almost free of clay ( Lime, especially boiling water, is a caustic substance, therefore, when working with it, you must follow safety measures. If lime gets on your skin or eyes, then rinse them with plenty of water.

Due to its high reactivity, lime (in any form other than dough) is stored in a dry place, protecting from water access.

When solutions are prepared using ground quicklime, pouring it into a concrete mixer, they harden much faster, and the coatings from them are much stronger. In addition, such solutions can be used at low temperatures, as they are heated by the heat released by lime, and quickly harden.

Lime decorative plaster can be tinted using alkali-resistant pigments / dyes. The color of others “eats” lime. For tinting, no more than 5% (without risk of decreasing strength) pigments are added to the lime solution, obtaining colors:

  • green (chromium oxide)
  • yellow (ocher)
  • brown (umber)
  • red-brown (iron minium),
  • blue (ultramarine),
  • black (soot).

Paints are not afraid of light, however, bright, saturated tones cannot be obtained.

Advantages and disadvantages

Lime plaster its pros and cons.

It belongs to mineral mixtures, therefore, it has their main advantages:

  • environmentally friendly
  • fire resistant
  • has a low price,
  • it adheres well with mineral substrates, as well as with wood, drywall,
  • vapor permeable (allows the walls to breathe)
  • maintainable
  • durable
  • sufficient strength for wallpapering is achieved lime plaster for interior use after about a day,
  • workable
  • bactericidal (does not allow the appearance of foci of fungus and mold).

The main of the minuses:

  • long-term strength gain (coating holds nails in 2 weeks)
  • low water resistance
  • unstable - cracks appear during vibrations,
  • you need to protect yourself from strong alkali,
  • insufficiently high strength (inferior to others in this).

Scope of lime solutions

The classic material of construction is used for roughing and finishing of residential premises, facades, auxiliary buildings. With certain additives, lime mortar is used to decorate even wet rooms such as the bathroom.

Like other mineral plasters, lime is not used in new buildings until the final shrinkage of the building, as well as in areas with seismic properties and near railway lines, as they are prone to cracking.

On sale there is also an improved mixture of dry lime-carbonate plaster. Carbonate lime is obtained by co-milling limestone (60-70%) with boiling water (30-40%). Due to this, the compositions based on it harden in air and in a humid environment. Less water is required to prepare the water; the drying time of the coating is reduced. Such mixtures are intended not only for the preparation of lime mortar for plaster, but also for masonry mortars. The difference in the proportion of added water: to plaster, 1 l of water is taken per 1 kg of dry mix, for masonry - 0.5-0.7 l of water.

For the facades of houses, lime-sand colored plasters are popular, in which up to 20% of cement is sometimes added. They are inexpensive, easy to apply by hand or mechanically.

As a binder, hydrated lime - fluff is included in the building mortar. Such mixtures are used for various purposes, even added to mortars for floor screeds.

Slaking lime

To prepare a stucco mortar with lime slaking, you will need a metal tank, since in the process of hydration (violent chemical reaction with an increase in volume by 3 times) there is an increased release of steam and heat (up to 180 ° C). Capacity should be taken with a margin to increase the volume.

On the packaging with quicklime the blanking speed is indicated, which happens:

  • slow (> 25 min)
  • fast (8-10 min),
  • average (15-20 min).

To mix the mass during the process, you will need a shovel or a wooden oar. Regardless of the reaction rate, quenching is carried out for at least a day. The best lime is aged about 1-1.5 months.

Protective clothing is recommended to protect against splashes.

  1. A metal container is prepared where a lumpy or powdery bowel is laid out.
  2. The necessary volume of cold water is prepared (for the preparation of milk of lime, use 2 kg of ground boiling water + 2 l of water, for dough for 1 kg of boiling water - 0.5 l of water).
  3. Slowly pour in (in small portions) water (this is especially necessary for lumpy bowels, so as not to “coke”).
  4. As soon as the amount of steam formed decreases, a little more water is added and gently mixed.
  5. After the cessation of steam, the container is covered with a lid, leaving the mixture to reach for a day and a half.
  6. Stir again. Leave in a cool, dark place for at least 2 weeks.
  7. Stirring, filter through a sieve.

How to prepare lime mortar for plaster

For the classical composition of the lime mortar (with or without filler), a characteristic such as fat content is isolated.

  • very fatty (recommended composition 1 part of the test: 3.5-4 parts of sand),
  • greasy (1: 2.5-3) is often used for a topcoat (1: 1), plaster-free plastering (sand fraction Lime-gypsum mortar

By adding gypsum to the composition of the plaster mix, lime-gypsum plaster is made, the use of which greatly accelerates the finishing process.

For preparation, they take prepared lime mortar (3-4 parts), gypsum (1 part). 2 l of dough is placed in the mixing container

Pour a liter of gypsum, mix with a mixer, adding water. Then they put another 2 liters of dough, mix everything.

In order to obtain a sandless coating, gypsum powder is added in small portions to the milk of lime while mixing. The maximum coating layer is 2 mm. The composition of the coating mortar (gypsum - IT) for plaster:

  • dry - 1: 1,
  • slightly wet - 1: 2,
  • wet - 1: 3.

The cover is smoothed with a rubber or metal trowel without soaking.

The setting begins 5 minutes after the kneading, therefore, all work is carried out quickly, the complete processing of the layer is completed before setting, and the volume of the kneading is small.

To increase the lifetime, 10 ml of PVA glue is added to 1 liter of plaster mixture.

Lime-clay solution

Clay can be added to the plaster as a filler to reduce lime consumption, and a clay is added to the clay to increase its resistance to erosion by water. In both cases, the volume of the additive can reach up to 35%. The mixing of these materials is carried out in a metal container or in a tvoril (pit) before extinction, filling them with layers. Fill with water, incubated for at least 10 days, then mix, filter, add filler in the desired proportion to the composite test, if necessary.

Such compositions are used, as a rule, for interior decoration. Proportion (dough: filler):

  • for spraying - 1: 1 (for wooden walls, the consistency of the solution is semi-thick, for concrete / stone - more liquid),
  • for soil (base layer) - 1: 0.75: 0.5 (the last digit for sawdust or other fibrous additives),
  • for nakryvki - 1: 1 (dough: sand).

Fibrous fillers in plaster are used to increase the low strength of such solutions. Before adding fibrous fillers, it is advisable to impregnate with copper sulfate (5% solution).

Another way is to separately prepare a dough of lime and a dough of clay. The latter is prepared in advance, filling in a separate container with water, leaving it to stand for 2-3 days. Then, after draining the water that the clay did not absorb, knead the clay dough and mix it with lime. After this, pouring water and pouring sand, prepare a stucco clay-lime mortar, controlling its fat content. If it does not stick to the tool, add lime.

Lime and cement mortar

For universal use, a durable, plastic cement-lime mortar for plaster (CIR) is prepared with your own hands, or you buy a dry mix (CC) ready, which is enough to dilute in the right proportion with water. However, SSs are more expensive than self-prepared formulations. Therefore, we provide information for those who want to do it yourself.

Depending on the purpose (scope) of the solution, the composition and ratio of components may vary. Cement grades 400-500 are most often used (white for decorative purposes), and washed sand (may be river, quarry or ravine, quartz, etc.) of medium fraction is used as filler.

The compositions of the cement-lime mortar for plaster in different operating conditions differ in the ratio of components:

  • in bathrooms, cellars, cellars, where increased moisture condensation is 1: 2: 8 (volume of cement powder M400 - test - sand),
  • on smooth outer surfaces - 1: 1-3: 6-9,
  • surfaces that are systematically moistened and exposed to frost (foundation, basement area) - 1: 0.5-1: 4.5-6.

Dry components (cement powder, sand) are mixed, and then mixed with milk.

Lime-sand mortar

To prepare the starting lime-sand plaster for 1 part of the test take 2.5 - 4 parts of sand. The composition of the finish layer is different. Its formula is 1: 1-2 (see above). Sand can be mixed with milk or added to a dough diluted with water. The gray color of the raw lime-sand plaster will change to snow-white during the drying process.

Among other things, the strength of the coating depends on the shape of the sand particles. Gully (mined in the quarry mountain) sand has a gravel-like debris shape, better adheres to lime, as a result of which the coating strength is higher. River and sea sand has a rounded surface, so its adhesion is less. Such sand is also contaminated with clay-clay particles, which reduce the strength, and therefore needs to be washed.

Additional components

An improved composition, for example, for decorative plaster, is obtained using other types of filler.

  • stone flour (Venetian plaster),
  • perlite, expanded clay, expanded polystyrene (heat-insulating, sound-absorbing),
  • crumb of marble or other breeds (decorative compositions),
  • artificial fibers (fiber) or natural fibers (sawdust, wool, flooring) that increase strength, reduce heat transfer,
  • barite sand (protective mixture used in x-ray rooms),
  • shredded mica (increases weather resistance and water resistance, lowers static, protects against UVL).

Plaster for exterior work on a reinforcing mesh is made reinforced with fibrous materials (wool waste, finely spiked felt, etc.). Such a composition fills the mesh cells better, the coating is stronger. The volume of the additive is 0.5-1 parts per part of the test.

Work surface preparation

For the long-term operation of the plaster finish while maintaining strength, as well as appearance, the correct preparation of the base is important.

We prepare the surfaces for wall plastering with lime mortar in the following sequence:

  • we remove the wallpaper, inspect the wall to identify defects and weaknesses, tap the old plaster coatings (if left), beat off exfoliated areas,
  • neutralize foci affected by mold, fungus,
  • remove oil stains, rusty sags, efflorescences,
  • remove or isolate metal objects,
  • we repair punctures, cracks (for large we use a reinforcing mesh),
  • remove dust
  • primed with a composition corresponding to the base and finish material,
  • install lighthouses
  • dry.

Application technology

The lime mortar is applied in three layers, each of which has its own characteristics:

  1. Do not miss the work described in the paragraph on the preparation of the walls
  2. The first, called spray, is done to ensure reliable adhesion of the finish to the base. Has the consistency of liquid sour cream. Throws a bucket or trowel. Not smoothed out.
  3. Soil (the main layer with a thickness of 10-30 mm) is performed with a more viscous composition using a trowel between the beacons. If it is necessary to apply a thicker coating, the composition is applied in layers with daily drying of each layer. Align with beacons as a rule. After the start of setting, the installed beacons are dismantled, and the formed grooves are filled with solution.
  4. A cover (a finish layer, usually having a different composition, consistency like a spray) is applied with a spatula, or with a trowel several mm thick.

Nakryvka and spray differ from soil in composition. The concrete wall "asks" for spray from the lime-cement mortar. It is also used for coating when plastering facades. For rooms, a cover made of lime-gypsum mortar is preferable.

How to calculate the expense

Preparing for the finishing work, they ask the question: how much plaster will need to be prepared, and therefore - to prepare the plaster materials. There are two main factors that influence the flow rate:

  • type of mixture used for plastering,
  • wall curvature
  • finish texture
  • skill plasterer.

For an example of calculation, we take a cement-lime mixture. To calculate the flow rate, it is necessary to determine the average thickness of the plaster layer. To do this, we measure the deviation of the wall from a vertical plane. We set three beacons according to the plumb line and level, aligning them in one plane with a cord pulled between the extreme beacons. We select several points along the lighthouses (where the wall is closest to the vertical plane indicated by the lighthouse and where it is as far as possible), measure the height of the lighthouse above the wall there. Having measured the wall with lighthouses, we calculate the average thickness of the future coating. The sum of all measurements is divided by their number. Let's say the average layer thickness for the wall is 4 cm.

On the packaging, the manufacturer indicates calculated per square meter. meter wall consumption rate for a layer of 1 cm. For the selected mixture - about 15 kg. We need to multiply this number by 4. Therefore, the consumption per m2 of wall will be 15 x 4 = 60 kg. With a wall area of ​​6 m2, 360 kg of mixture or 12 bags of 30 kg are needed. It is recommended to add some quantity for the stock to the calculated value.

And another video about applying lime plaster:

The mixture improved since ancient times, as well as the advantages of lime plaster make it popular. In fact, no one has yet come up with an equivalent replacement for lime. We hope that, using the materials on the site, you can correctly choose exactly what is best in your case.

Storage and transportation

When storing or transporting a substance, it is necessary to ensure conditions under which the risk of moisture ingress is minimized. The lime substance itself, in the form of a powder, can even absorb moisture that is in the air.

The shelf life of the product depends on the packaging used. When lime is in paper bags, its properties will be maintained for 25 days. Providing the necessary conditions, lump lime can acquire an unlimited shelf life.

In storages, floors should be made of wood and raised to a height of up to 30 cm. Water must not be allowed to enter the substance, as there is a danger of fire. As a result of the fact that the water heats the calcareous material, in the event of a fire outbreak, water cannot be used to extinguish the calcareous composition.

The difference between quicklime and quicklime

The main difference between quicklime and quicklime is the chemical formula. The common thing between them is that the first is obtained as a result of the reaction during the interaction of the second substance with water.

Difference: the first is alkali, the second is calcium oxide, the first interacts weakly with water, the second, when mixed with it, turns into the first with intense heat, when you touch the first type, the heat is not felt, and the second substance is warm to the touch. in the production of various building materials: slag concrete, plaster, paint, silicate brick. Using these materials, work can be carried out at low temperatures. Lime can not be used as a finish for fireplaces and stoves, since during their heating carbon dioxide is released that is harmful to humans. Lime has found its wide application in agriculture and horticulture: processing of trees, fertilizing the soil, destroying weeds, additives in animal feed. It is whitewashed both by residential buildings and non-residential buildings. Quicklime is a product of natural origin, mined from a quarry with clay admixture. When mixed with water, lime powder is obtained. Quicklime is rarely used; it is mined thermally by the breakdown of calcium salt. It is used as a neutralizer of sewage pits and in the production of certain elements for construction needs.

Benefits Over Hydrated Lime

It has many advantages compared to the slaked variety:

  • high strength
  • absorbs less moisture
  • work with this material can be carried out in winter,
  • lack of waste
  • very extensive scope.

Quicklime is dangerous to human health, so it is advisable to carry out work in open space
using protective equipment.

A good advantage of quicklime can be considered a low cost in comparison with other mixtures. The calcareous material is resistant to temperature changes, it does not crack, and has antimicrobial properties.

Specifications

Lime is a substance that is often found in nature (mainly in rocks), and the product is manufactured in full compliance with established standards, because mixtures on this basis must perform protective functions at a high level.

Finished lime should consist only of carbonate rocks (limestone) with a low clay content. Various additives and impurities are allowed in the composition of the material based on GOSTs, depending on the application.

Limestone looks very similar to chalk or coke, but they have different properties and are not interchangeable. To distinguish limestone from chalk, you can drop water on them. The chalk will not give any reaction, but the limestone will begin to foam and give off heat. If you use chalk to whitewash the walls, it will leave marks on clothing and surfaces in contact with the wall. Lime leaves no traces, so it is most often used for whitewashing walls.

Quicklime is divided into three grades (1, 2 and 3), and quicklime is divided into 1st and 2nd grade. The exception is powdered quicklime, it is divided into two grades and has additives. The remaining types are made without impurities.

By external physical indicators, for example, by color, it is possible to determine the grade of material. After thermal treatment of limestone, quicklime is obtained, and if it is white, it means that the material does not contain additives and belongs to a high grade. In other cases, the material has a grayish color, most often it is dolomite and hydraulic lime.

The manufacture of calcareous material consists of mining the rocks themselves, crushing them to the required size and subsequent calcining in special furnaces. Currently, shaft and rotary tube furnaces are most often used because they provide a uniform temperature effect on the material and a continuous firing process.

The strength of the raw materials is affected by the temperature during firing and the production process itself. There are three options for the strength of the finished product: hard-burned, medium-burned and soft-burned lime.

Mildly deified lime is very popular in construction, due to the following properties:

  • the blanking process takes place quickly, in about 3 minutes,
  • such material has a small size and low density.

Lime is a low hazard class, but safety and handling must be followed during transportation and storage. Since quicklime reacts violently with water, you must make sure that moisture cannot get on the material.

The composition of lime most often includes various mineral additives that improve the properties of the material: granulated blast furnace slag, quartz sand and other substances.

Characteristics of slaked lime

According to GOST, slaked lime material has the following characteristics:

  1. The specific gravity of the fluff should be from 450 to 550 m³.
  2. The main properties of hydraulic lime are strength and compression.
  3. 90% of the calcium and magnesium content in the composition, in relation to 10% of water, is hydrated lime according to GOST. Less quality products have a small amount of these substances, at a higher percentage of water.
  4. A qualitative composition is considered to be one in which a change in volume does not affect uniformity.
  5. Slaked lime includes: mineral additives, quartz sand, carbonate rocks, blast furnace slag.
  6. The acidity of slaked lime is 12.4 pKa.
  7. The density of the product is 2.211 g / cm³.
  8. It is interesting that slaked lime changes the technical characteristics if clay was admixture in its initial composition.

What is the difference between quicklime and quicklime?

When answering the question of how to recognize hydrated lime or not, you need to know a number of basic differences between them:

  1. Areas of use. Both materials are used in repair and construction works. Quicklime, unlike the source, is less popular, because when interacting with water it becomes a lime powder, which is used to neutralize wastewater and some types of construction work.
  2. Properties and specifications. Slaked lime has a finite composition of the formula and will not be able to change during any manipulations, while quicklime can be different in properties when it is changed.
  3. Composition and formula. Quicklime is an alkali that practically does not interact with water and does not give heat when touched, unlike quicklime.

General information

Lime is a generally accepted concept around the world that conditionally combines products of firing (and subsequently processing) chalk, limestone and others. Classification is carried out in accordance with the chemical composition. As a rule, the word "lime" refers to quicklime and the product of its interaction with water. This material may be in powder form, milled or in the form of dough. The quicklime formula is CaO. This compound is a product of firing rocks, in which it acts as the main chemical component. It actively interacts with water. As a result of hydration, hydrated lime is formed - Ca (OH) 2.

A few interesting points about lime

  • If there is no lime to be applied as a fertilizer, then ordinary wood ash can replace it. It is also able to lower the level of soil acidity, and it is also rich in potassium. This type of fertilizer is applied in larger quantities than traditional limestone or dolomite.
  • Many inexperienced gardeners make the mistake of replacing quicklime with ordinary gypsum. It is not worth introducing this element into the soil, since it has no effect on acidity. Its application is required only in highly saline soils in order to crystallize excess salt mass.
  • The frequency of use of this type of limestone directly depends on what other varieties are introduced into it. When making mineral elements, adding lime is required more often than when adding organic matter. Organics is a strong fertilizer in itself, after which additional application of limestone is not required.
  • Not all popular garden crops perceive lime well, this fact must also be taken into account. Potatoes, tomatoes, sorrel, peas, parsley, carrots, zucchini and pumpkin are categorically not tolerated by lime. In gardening, there are also plants that react extremely negatively to the addition of lime to the soil, among which it is worth noting chokeberry, gooseberry, strawberries, raspberries, blueberries.

All these nuances you need to know before you decide to liming your site.

How to make slaked fluff

For the production of slaked lime, you must follow some rules. Dehydration (extinction process) is required to be carried out outdoors. The raw material itself must be placed in a tank or container. Since a rather large amount of steam will be released in the process, you need to protect yourself. The material itself can also cause harm to humans and even burn the skin. This is why it is necessary to protect the skin of the hands and the whole body, eyes and respiratory tract. You can not do without a suit or special clothing, gloves, glasses and a respirator. Then everything will be safe for your health.

It is important to remember that rush is not needed in this matter. The quality of quicklime may vary, one is quenched quickly, the other for a long time

If you do not finish the whole thing, then it is possible that the material will smoke in the finished only made plaster. When you use slowly extinguishing lime, pouring it into water immediately is not recommended. It is better to do this in small portions. The medium and quick-extinguishing is poured until the steam completely disappears to prevent burnout.

Note! Freshly slaked lime may have residual starting material. They are extinguished again, and then removed

After dehydration, the amount of lime will be greater. From 1 kg of quicklime you can get 2 or more. Quicklime and quicklime are obvious. But where are these materials used?

Application

  • Since ancient times, lime fertilizers have been used in agriculture to increase soil fertility and for liming, that is, to reduce acidity. Solid calcareous fertilizers, such as chalk, limestone, dolomite, are ground or burnt before being applied to the soil. Soft calcareous fertilizers act more efficiently and are applied to the soil without preliminary treatment - natural dolomite flour, lake lime (drywall), calcareous tuff, marl. Lime fertilizers include products of rock processing: quicklime burnt lime (ground or lump) and fluff (slaked lime), as well as industrial waste, such as cement dust, white flour, blast furnace slag, shale and peat ash, defecation mud, etc.
  • Painting trees. Dilute 1 kg of lime into 4 liters of water. After a couple of days, the solution is ready for use.
  • Spraying plants. Copper sulfate is added to the lime water and two hours after preparation they begin to spray.
  • Whitewashing ceilings and walls. Here the proportion will be different: 1 kg of lime per 2 liters of water. Then add water until the desired consistency is obtained. Let the solution stand for a couple of days and strain it.
  • A fluff (or dry calcium hydroxide) does an excellent job of protecting against moisture, disinfection, and improving the bonding qualities of cement and concrete mortars.

Healthy Lime Milk

In addition to quicklime, there is the concept of milk of lime. His summer residents are actively using instead of traditional whitewash, they spray the whole trees and shrubs with the composition. With this composition, a natural protection is created for crops from possible sunburn and severe overheating, the bark is dressed in such a “warm shirt” for the winter, spring flowering of trees is delayed for a week. In this way, gardeners save their fruit trees from spring return frosts.

Milk of lime is prepared very simply: you need to take 1-2 kg of quicklime, dilute it in 10 liters of water. If such a prepared solution is used to fill all the pest larvae on tree trunks, then their further development will stop, the caterpillars simply will not be able to move normally.

Slaked lime

Slaked lime - calcium hydroxide or slaked hydrated lime (fluff), it can also be called milk of lime or dough - it depends on the consistency. Get it by adding water to quicklime. In the fluff, water is present in a ratio of 60-80 percent, and milk of lime or dough is obtained with a larger dilution of fluff with water.

The process of extinguishing lime is called dehydration. They produce it in open space, in prepared pits or crates. There are quick-extinguishing lime - up to 8 minutes, medium-extinguishing - up to 25 minutes and slow-extinguishing - over 25 minutes.

During the quenching process, heat is generated, water is added gradually so as not to lower the quenching temperature. The desired consistency is regulated by the amount of water, when the raw material ceases to absorb water, its addition should be stopped. The yield of slaked lime depends on the quality of the initial raw material: 1 kg of premium grade raw material gives about 2 kg of lime dough.

Slaked lime storage

After dehydration, the lime is aged in an equipped pit for two weeks - if it is used in solutions or for masonry. And about a month - if it is used for plastering.

From above, the solution is closed with a layer of fine sand up to 20 cm thick, in sub-zero temperatures so that it does not freeze, you can also fill up a layer of earth on top of sand - up to 70 cm. A pit with covered substance should be fenced and marked - for the safety of people and animals. Exposure is necessary to complete the process of extinguishing even the smallest particles of raw materials; non-quenched particles can contribute to swelling of the future coating.

Where applicable

Slaked lime is used everywhere in construction, horticulture, medicine, and water:

  • soften hard water with it,
  • used for fertilizer production,
  • interior decoration
  • protect tree trunks from insects and rodents,
  • added to building mixtures to protect against fungus, mold.

Quicklime is classified according to many indicators, allowing it to be divided into different subspecies. By the degree of grinding of particles, lumpy and ground lime can be found. Lumpy species are characterized by lumps of various shapes, fractions and sizes. In addition to calcium oxides, which are the main component, and magnesium oxide, to a lesser extent present in the composition, other additives may be in the mixture.

Depending on the degree of calcination of the lump material, medium-calcined, softly-calcined and heavily-calcined lime are distinguished.The degree of firing of the material subsequently affects the time taken for the extinction process. During the firing process, the composition is enriched with aluminates, silicates and magnesium or calcium ferrites.

The degree of firing is affected by the residence time of the product in the furnace, the type of fuel and temperature. With the bulk method of firing, where coke is used as fuel, and the temperature in the furnace is maintained at a level of about 2000 ° C, carbide (CaC?) Is obtained, which is used later in various fields. Lump lime, regardless of how and to what extent it was calcined, is an intermediate and therefore is subjected to further processing: grinding or slaking.

The composition of the ground mixture is not much different from lumpy. The difference lies only in the particle size of the lime. The grinding process is used for more convenient operation of calcium oxide. The crushed granulated or ground quicklime reacts faster with other components compared to the lumpy appearance.

According to the degree of grinding of particles, crushed and powdered lime are distinguished. For grinding, crushers and mills can be used depending on the required particle sizes. When choosing mills and grinding schemes, they are guided by the degree of lime calcination, and also take into account the presence of solid inclusions and flaws in the calcination process (underburning or burning). Particles of a material that has been burned to a high or medium degree are crushed by impact and abrasion in special containers of ball mills.

Lumpy mixture is used to obtain different types of slaked lime. The quenching process (inorganic chemistry) is very violent, water boils during the reaction, so the lump mixture is called "kipelka". A different percentage with water gives different compositions of consistency. There are three types of slaked lime: limestone milk, limestone dough and hydrated fluff.

To obtain a lime dough, less water is required, but its amount is still several times greater than the mass of lime prepared for slaking. As a rule, in order to obtain the desired pasty-like consistency, water is added to the product, which is 3-4 times superior in weight to the basic substance.

A powder mixture or hydrated fluff is obtained in a similar manner, but the amount of added water is less than for a pasty or liquid composition. Fine powder or fluff, depending on the percentage of aluminoferrites and silicates, is divided into air and hydraulic types of lime.

The time taken for the quenching reaction allows us to classify quicklime as quick-extinguishing, medium-extinguishing and slow-extinguishing. Quick-extinguishing species include compounds, the conversion of which takes no more than 8 minutes. If the quenching reaction takes longer, but the conversion does not last longer than 25 minutes, then such a composition is referred to as a quenching species. If it takes more than 25 minutes to extinguish the reaction, then this composition is of the slow extinguishing type.

Lump lime

Lump lime is a mixture of lumps that differ in size. It consists of calcium oxide and magnesium, as well as materials such as calcium carbonate, aluminates, silicates. Magnesium or calcium ferrites, which are formed during the firing of raw materials, can be added.

Good concrete strength is ensured due to the fact that lump lime requires a very small amount of water (due to fine grinding of the material) and practically does not generate waste.

Ground lime

Ground lime has the same composition as lump, but the difference is that the lumps of raw materials are grinded much stronger and more thoroughly.

The main advantages of ground lime:

  • strength,
  • water resistance
  • quick hardening.

To increase or decrease the hardening rate, calcium chloride or sulfuric acid is often used (gypsum material is also suitable).

Hydrated lime

Hydrated lime (also called fluff) is a slaked form of material with a highly dispersed composition. Extinguishing occurs by adding water to the lime stock. To prepare such a solution, 70 to 100% water is added to the powder.

In order for lime to completely go through the process of quenching, it must be placed in a special pit for 2-3 weeks. So she will gain optimal strength and ductility. The minimum cancellation period is 36 hours. In order to prevent the burning of raw materials, it is advisable to add water gradually until the steam ceases to be released.

Lime dough is formed with sufficient addition of water to form a plastic material. You can also find such a solution as milk of lime (mainly used for whitewashing tree trunks). Milk of lime is obtained by adding excess water to the lime dough.

How to use?

When preparing a mortar, it is important to ensure the safe interaction of raw materials with water for humans. It is advisable to work in a well-ventilated area, and preferably in an open space

Since the substances used are chemistry, it is necessary to adhere to safety rules when working with such materials.

The powder substance can be used both in dry form and in liquid form. To prepare a liquid solution, the powder is poured into a container and filled with water. The solution must be mixed and diluted to the required consistency.

To whitewash the trees, the raw material is diluted with water and applied with a wide brush to the tree trunk. But due to the liquid consistency of the solution, you will have to process the barrel several times. In order to reduce the time of work, you can add clay, milk, PVA glue to the solution. These ingredients will make the mixture thick and viscous; it will evenly lie on the surface. Before processing the tree, you need to remove all dead layers of the bark, without damaging the trunk.

To protect plants from fungus, you can use soda ash instead of lime, because soda is faster and completely soluble in water.

Before using bleach, it is necessary to check the reaction of the surface. To do this, you can treat a small area, and if it remains intact after about 10 minutes, then you can use bleach for the entire surface. First, water is added to the raw material in a small amount and stirred to the state of sour cream, and then gradually more water is added, also stirring, until a liquid solution is formed. In dry form, bleach is used only on wet surfaces.

In construction, it is recommended to use quicklime, ground lime for the manufacture of plasters, slag concrete, and coloring elements. In other cases, slaked lime is used, which, thanks to moisture resistance, prevents the formation of mold.

Pushonka has a wide scope of application: from domestic needs to construction. To prepare the fluff, it is necessary to pour raw materials into a metal container without rust (or into a plastic one) and gradually add water, stirring the solution. Once the mixture is ready, you must leave it to brew for several hours or days. The longer it stands, the higher its quality and strength indicator.

Storage and cost

The price of quicklime depends on the variety, type and quantity in which the material is needed. So, for example, the cost of a bag is from 300-400 rubles, and tons - from 8-10 thousand rubles. Product storage is carried out in warehouses with mechanized unloading and loading. The duration of the content of the compound should not be more than five to ten days (to avoid carbonation and hydration of calcium oxide). Bulk or ground quicklime is sent to the consumer in containers, tar bags or in wagons equipped for its transportation, or in cement trucks. Packaging in bags is carried out using modern units with shaking devices. In bags, the product should be stored no longer than fifteen days.

Achieving any goal is daily work.

If your goal is to get a good harvest, then you will need to not only invest your work, but also provide your garden and vegetable garden with proper care, attention and care. Surely, the experience of many years has taught everyone that when growing something in the garden, you can’t do without chemicals

Most likely, everyone had heard about slaked lime in a particular area of ​​conversation. Slaked lime (or, as it is also called - fluff) has a chemical name - calcium hydroxide. It is interesting that such lime is used in various fields: construction, water softening, leather tanning, dentistry, and the chemical industry. Also found application in gardening.

The composition of slaked lime is quite simple, it is dominated by calcium oxides. The process of obtaining (extinguishing) is also not intricate, and consists in adding water and thoroughly mixing.

It is not difficult to prepare slaked lime (fluff), for this you need to extinguish (mix) it with water, which takes about 10-20 minutes. In the process of extinguishing, a safe, useful top dressing is performed.

The use of slaked lime is quite widespread in gardening. A simple, unpretentious method has long been one of the main tools of experienced gardeners. Some of the application methods:

  • Weed control: some of the weed species can be completely removed from the garden, for this you should liming the soil in the autumn. The application rate is 300-400 gr per sq.m. After the procedure, you will not be afraid of weeds: horsetail, wheat grass, woodlice, sorrel.
  • Slaked lime can also be added to the compost pit - this will speed up the decomposition of its contents.
  • Deoxidation of the soil using liming requires compliance with the norms and doses: heavy and clay soils - 600-900 gr. per sq.m, light, loamy - 400-500 gr. per sq. m, light, sandy - 300-400 gr. per sqm Liming of the earth is carried out 1 time in 3-4 years.
  • The process of whitewashing trees is very simple. It is recommended to use lime of the highest or first grade. Lime is bred to obtain a rich white color, the approximate proportion is 1: 1.

What is quicklime?

Quicklime lime has a crystalline structure, it is formed during calcination of limestone. There may be impurities in this material, they are usually not more than 8 percent. Lime is produced from carbonate rock, and mineral additives, quartz sand or special slag are also used. Lime is made in compliance with GOST; it belongs to the second hazard class.

Today, quicklime is not used instead of cement, that is, for wall decoration, as it is able to absorb moisture, resulting in mold and fungus. It is used for the production of various building materials, such as cinder concrete, plaster compositions, colorful products and so on.

Purpose and advantages of slaked lime

Hydrated lime (also slaked) is a simple white powder that has a heavy base, but is easily dissolved in water.

In fact, lime is the common name for all products / materials that come out during the firing process.

There are several types of lime, which classified by blanking time:

  • quick blanking. The process takes from 8-10 minutes, even there are large volumes,

  • medium blanking. The process lasts about 25 minutes,
  • slow blanking. The entire process of extinguishing on average takes more than half an hour.

Because slaked lime has a wide field of application, it is also classified by solidification density. Here is her formula. Today there are two types of hardening:

  • hardening of air type. This type has found its application in construction. It is added to liquid construction mixtures in order to achieve the required density. Often it is added to concrete. All recommendations must be followed, one of which is dry conditions, the presence of air,
  • hydraulic hardening. This type of hardening is relevant in those places where it is necessary to achieve maximum strength. Such slaked lime is used in construction, which occurs under water. For example, during the construction of underwater bridges, or when laying the foundation for ports. Here are the proportions of cement for the foundation,
  • this type of hardening is of two types, different in the method of preparation: highly hydraulic and slightly hydraulic.

The material has many characteristics and classes. Depending on the grinding, it can be divided into three simple groups. Each of which has found its application:

  • lumpy. This type of material is sold in tons, in bulk, and looks like flour, or starch,

  • crushed. You can store such lime in warehouses in bulk. Sold in tons,
  • powdery/ shallow. They are sold in large enough quantities, as well as in small bags of several kilograms.

Production, standards in accordance with GOST

Lime she is a little fluff, outwardly has no distinguishing features. It is a special white powder, most often a small fraction.

It is interesting that when you start to breed lime with water, its volume almost doubles.

The density of the powder with which to start work is 400 kg per cubic meter, while the humidity should be 5%. The fluff material is made very quickly, the main thing is to observe all proportions and technology.

When it comes to lime (slaked) for use at a construction site, the process can occur, as at the construction site itself, also in the factory.

In quicklime, lime should take 1/3 of the total volume, water will be added in the same amount. Here is the quicklime formula. All the rest of the space in the tank is necessary so that the material can complete its cooking process.

In the very first minutes of combining the powder with water, a reaction begins, and the material increases in volume.

You need to know that if the prepared lime is immediately mixed with concrete, then its quality will not be very high. This is due to the fact that the material, a small percentage of the dry mixture, and if you do not wait a certain time, the process of extinguishing lime will not be completed.

As a result, the material will not cope with its tasks. Absolutely every building material must comply with all the rules and state standards.

Dry powder lime is divided into several classes, and the difference is in how much the material contains direct content of calcium and magnesium oxides. For example, the best material is the highest grade, classified under such standard GOST 9179-77, has such a compound CaO + MgO, but in an amount of 90%.

But the second grade of such material, the compound CaO + MgO will be in a percentage of 80%. Speaking about the grades of the material, the lower it is, the less water you need to spend on its preparation. Which indicates that it contains a minimum of calcium oxide and magnesium.

For example, in the case of the fourth grade, the water necessary for the quenching reaction is taken in a proportion of 60% of the amount of dry lime.

The specific gravity of lime is 450-550 cubic meters. The price of the material is quite adequate - from about 3,000 rubles to 5,000 rubles per ton.

How and where is lime used?

Each of us came across such material as slaked lime. Its scope is so diverse that it can be found even during the preparation of certain dishes. But this is a rarer option.

Most often we we encounter it in the country, at the construction site. Here we are talking not only about large construction projects, but also in private construction projects.

Can I use and how is it used in gardening and in the garden

Slaked lime found its application in horticulture:

  • lime takes part in fertilizer production, which is used in the garden and horticulture,

  • garden. A special solution is made from such material, with which the beds are whitened to protect the plant from various kinds of diseases, and also in order to fence the beds from parasites,
  • for whitewashing trees. This procedure not only guarantees protection of the tree bark, but also gives them a beautiful look.

But this is far from everything where such material can be used. It can be used:

  • in the process of tanning the skin,
  • add lime to the connecting systems to clean the sewers,
  • it is interesting that lime is added to the production process of E 526, which in turn is used in the food industry,
  • even in dentistry you can find this material. He found his application in the simple disinfection of canals in the roots of teeth (canals).

There are a lot of industries and spheres of human life, they use it only in the slaked form, but again, in order to get the desired result, it is necessary to distribute the lime in the correct proportion.

Lime is also used in the disinfection of garden tools. Process only fresh blanking material. The process is simple - the material is neutralized in a proportion of one to one, after which it is allowed to dry, after which milk of lime is prepared.

Scheme of material preparation:

  • one kilogram of lime is one liter of water,
  • let the material cool and dry
  • add another liter of water.

Such material can be used not only for disinfection of garden insurgent, but also for disinfection of premises.

For more information on the use of lime, see the video:

Proportions for whitewashing walls during construction in the country

When a dry material powder and simple water are mixed, a certain chemical reaction is obtained, which in turn releases a large amount of heat.

To avoid unpleasant situations (eye contact, skin burn), you must follow all safety rules.

It does not matter where the process of mixing the powder with water is carried out. In the factory, in the summer cottage, you need to do all the work, in a special protective suit and gloves.

Professionals recommend mixing materials in containers where there is no rust, it is best to choose a plastic container.

If you have a large volume, then it is better to take a large metal barrel. The workflow is a simple manipulation that needs to be taken seriously.

The first thing to do is to measure the right amount of dry material and send it to the prepared container.

Then pour cold water into the powder. It is best to fill the water not immediately, but in small portions and be sure to stir.

The ideal scenario is to leave the cooked lime to stand for a couple of hours, it is best to leave it alone for a couple of days.

If you will whiten the house, it is better to prepare the mixture in advance. The process of whitewashing itself will cause itself nothing complicated. Simply prepare the solution in advance. For lime to be white, it is best to take material of the first or second grade, and mix with water in proportions of one to one.

Before you start whitewashing the walls, you need to mix the solution well. Here about the putty of the walls under the wallpaper. With a large brush, start to smear the walls and ceiling.

Wizards recommend starting the entire process from the upper left corner. It is necessary to lubricate carefully, without leaving spaces.

As practice has shown, one layer is not enough, so you can apply whitewash in several layers. The process of whitewashing trees, in fact, is no different from whitewashing walls. Here about mdf for walls. The same solution, the same brush. Speaking of processing plants, the solution needs to be sprayed over the entire area of ​​the plants.

Safety measures when working with lime mortar

As mentioned above, when working with such material, you need to be very careful and follow the instructions of professionals. This is due to the fact that the material is considered caustic. Simple rules and recommendations will help you protect yourself from possible unpleasant situations:

  • when working with such a white powder material Protective glasses and gloves must be worn.
  • when you poured water into the powder, the quenching process begins. It is best to keep a distance from the tank in which the blanking process takes place. This is due to the fact that during the heating of the water, it is possible that the solution will spray,
  • Be sure to protect the respiratory system. You can do this with a cotton gauze dressing,
  • if lime gets on your skin, be sure to remove it with a cotton swab moistened with sunflower oil. A compress should be applied to the site that was affected by the solution. Water with 5% vinegar,
  • if such a solution gets into your eye, rinse immediately with plenty of warm water. If necessary, consult a specialist.

Conclusions

The advantages of such a material are obvious: easy to use, has good disinfectant properties, has a wide scope.

It can be said that lime is a unique material. It is suitable for a large number of intermediate works. Its low cost makes it popular. A material can do a lot of useful work, and you don’t need a lot of effort, time and money.

Liming soil

Many know lime as a building material, but gardeners and gardeners use it as fertilizer for the soil.

The main purpose of this fertilizer is to lower the level of soil acidity. Most cultivated plants grown in gardens grow well on slightly acidic soil. If the land is deoxidized regularly, it will be possible to grow more and better quality crops on it.

What is lime?

It is a simple calcium oxide used in many industries and other fields. Gardeners use this substance in order to cultivate the soil - to lime.

The lime used for horticultural purposes is slaked and quicklime.

Slaked lime (fluff) and its use in the garden is known to everyone who cares about their plantations for at least some professional way. In order to obtain such fertilizer, it is enough to stir ordinary lime with water.

Quicklime used in its original form, without mixing with water. In properties, it is similar to the slaked version, but it is worth using it more carefully - not all plants will tolerate this well. Deoxidation of soil with quicklime will also help protect plants after planting.

Use for soil fertilizer

You can buy lime in any specialized store and it is better to do it in bulk. Firstly, it will be cheaper, and secondly, liming a large area of ​​soil requires a lot of material, it will be inconvenient to constantly buy it.

Liming should not be carried out just like that, without understanding the features of the use of lime on acidic soil. If the procedure is not carried out at the right time, at a critical moment (in the fall, during harvesting or in the early spring), the plants will remain unprotected.

To overdo it with lime is also dangerous, regardless of how the excess was achieved - in several treatments or during one. Alkaline soil does not cause direct harm to plants, but prevents them from absorbing the main macroelements from the soil.

IMPORTANT! It is also worth careful to use lime in parallel with other fertilizers - for example, the substance definitely should not be applied simultaneously with manure, there will be no benefit from this.

Instructions for use of limestone flour

After the first time, an experienced gardener will figure out how to specifically lime his plot, but a beginner’s schedule, which is suitable for most, will not hinder a beginner.

The best option to buy if the soil is medium or high acid - limestone flour or ground limestone. Its dosage is easy to calculate, and the damage to plants is minimal.

The depth to which the substance is to be injected is important - usually this is the standard 20 cm in depth. However, if liming is applied to soil where the plants are young and vulnerable, a specially reduced dose is often introduced four times. Such an “easy” option is introduced into the ground to a depth of not more than 4-6 cm.

IMPORTANT! Liming must be carried out at least once every five years, since during this time even the soil that has been brought back to normal acidity will return to its original state (applies to those types of soils for which the acidic environment is natural). The maximum number of treatments is 1-2 times per year.

Optimal season for processing soil with lime - fall.

Autumn harvest for a while leaves the land free, because the gardener can easily dig up the soil and at the same time do everything necessary without risking the plants. For the period that will pass before planting new plants on this soil, the fertilizer will have time to act.

You can also lime in the spring, but more carefully. When to apply lime for fertilizer to the soil - in the fall or in the spring, it is everyone’s business, except that the second option requires more experience and can harm the plants if the process is wrong.

Normalization of soil acidity

It is the reduction of acidity to the norm that is the main reason why gardeners use lime to fertilize the soil. Sometimes it’s enough just to sprinkle the area with the right dose — the rest will be done by the lime flour and the processes that it provokes.

Soil has primordial acidity. Before planting anything on it, it is better to find out the degree of acidity and soil type - this will greatly simplify the selection of doses of fertilizers and the substances themselves.

Degrees of land acidity it happens:

  1. Alkaline: negative acidity, liming is not required.
  2. Neutral: pH 5.5-6, also does not require any manipulation of itself.
  3. Weak: pH 5.1-5.5, sandy and sandy loam soils with such indicators are not treated with lime.
  4. Average: pH 4.6-5.0.
  5. Strong: pH 4.1-4.5.
  6. Very strong: pH ≤ 4, with such indicators, any soil urgently needs acidity normalization.

Depending on the acidity of the soil, the gardener must calculate the liming schedule and adhere to it if a stable crop is needed.

Acidity per se cannot normalize. There are some cultures that are comfortable in an acidic environment, but they are in the minority - cultivated plants grown in vegetable gardens and gardens prefer an alkaline environment.

Weed control

The second purpose of this fertilizer is weed control. Weed grass, which in the absence of control and timely destruction by the gardener becomes a real problem, growing and interfering with plantings, does not tolerate alkaline soil.

Among such lovers of acidic environments, you can see many notorious pests:

  • Ledum,
  • sedge,
  • creeping buttercup,
  • big plantain
  • sorrel,
  • wild mustard
  • meadow cornflower
  • club clown
  • daisy,
  • cinquefoil etc.

You can get rid of all these plants not only in a physical way, but also by simply changing the acidity level to a lower one - weeds simply cannot exist in such conditions and die without giving birth.

It is advisable to use lime as a measure against weeds. in the fall - In spring, plants are already viable and sprouted in the ground, to fight them is a little pointless.

Whitewashed quicklime trees

Even those who do not have their own garden or any other household containing fruit trees, noticed that the trunks are often treated with white mortar. This is a well-known rule of any gardener who wants to keep the trees in the best condition - lime is a good protection for them.

Why is this is necessary:

  1. Thermal insulation. Frost does not harm the tree as a whole, but with severe temperature changes with humidity, ice can appear that penetrates under the bark and spoils it, depriving the tree of protection.
  2. Parasite protection. Many pests feed on bark, but the lime-coated shell is not affected. Also, the chemical composition of such a whitewash prevents the development of diseases typical of trees.
  3. overheat protection. Not everyone knows that woody bark tends to overheat, crack and fall off pieces from the trunk, and lime reflects rays well.

The whole tree does not need to be processed with lime - only the lower part of the trunk needs to be “painted”. Such preventive procedures for trees are carried out in autumn and spring - before winter cold and summer pests.

It is believed that young trees cannot be protected in this way, but this is a myth. On the contrary, the thin bark of such plants needs even more protection.

If the gardener is worried about the state of the bark, he should think in advance how much substance will be used - the norm for an adult tree can be halved.

Basic information

The composition of lime plaster includes the following components:

  1. Slaked lime.
  2. River sand (filler).
  3. Water.
  4. Additional components for imparting uncharacteristic properties (cement, gypsum, clay, PVA glue, dyes).

Self-diluted, components mix in layers: 1 sand and 1 lime layer are mixed, then the following parts of materials are added. Next, the resulting mixture is poured with warm water and stirred. This technology prevents lime settling.

Plaster is applied manually (with a trowel, grater, rule) or pneumatic machine. The mechanized method carries out work faster and better. The layer is flat.

Before application, the surface is thoroughly cleaned. The old finish is removed, traces of construction work. Defects are leveled, mud and greasy spots are removed. For better adhesion, a primer is applied.

When applied to a concrete surface, additional reinforcements are not required. An reinforcing mesh is installed on gas blocks and a tree with self-tapping screws.

The advantages of limestone plaster

  • Environmental friendliness. All components included are completely environmentally friendly. Toxic and harmful fumes are not emitted, there is no sharp and unpleasant odor, which allows for construction work without additional protection inside the building. The only caveat - you must be careful when self-extinguishing lime.
  • High adhesion. Lime plaster can be applied to surfaces from any materials. In special cases, the erection of fittings will be required, but all work processes are quickly and easily carried out. The quality of the result does not depend on the draft material. Lime plaster can be used for wood, concrete, gas-block and stone surfaces. According to this parameter, the product is universal.
  • Plastic. After solidification, a strong and reliable structure appears. At the same time, the plaster layer retains plasticity, due to which, cracks and other defects characteristic of other building products do not form on the surface. Smooth and reliable surface lasts for several decades.
  • Air conduction. Lime plaster is a "breathable" material. The structure of the plaster layer conducts air well. This provides an optimal and high-quality microclimate.
  • Bactericidal property. Building material prevents mold and mildew. Resistance to the formation of harmful bacteria is maintained with increasing humidity in the room and with other changes in the microclimate.
  • Ease of application. Due to the high adhesion rate, it is convenient and easy to work with the finishing product.You can apply lime plaster on your own, without having professional knowledge and skills. Since the material is universal (it can be easily applied to any surface), the use of complex structures and equipment is not required. For finishing, it is enough to purchase standard tools for working with plaster.
  • Quick result. Lime plaster has a quick setting. Finishing work is carried out quickly, because the next day, after applying the plaster layer, you can use putty and other products.
  • Cost. This finishing material is relatively cheap. Expensive components are not included. Mixtures with additional properties are more expensive, since optional elements are used to impart these characteristics.

The disadvantages of lime plaster

  • Moisture. It is not recommended to use finishing material if the room humidity level is more than 60%. The product is not suitable for use in the kitchen, in the bathroom and other places where there is too much moisture. Applied under adverse conditions, the plaster layer will quickly collapse, since initially the parameters did not meet the standards. Additional components in the composition do not guarantee the durability of the structure in humid air.
  • Setting speed. The material quickly hardens, which is its advantage. However, due to this feature, the product must be applied quickly and without errors. Breaks during workflow are excluded. Before applying, it is necessary to carefully consider an action plan, so as not to spend time on this in the process. Also, you need to calculate the exact amount of the mixture that will be needed in the near future. For mixing, bulk containers with a flat bottom are required so that small particles do not penetrate the structure.
  • Strength. Compared with other types of plaster, the lime composition has a lower strength. On the surface there are scratches and damage after mechanical exposure. Strength can be improved by adding PVA glue or cement.
  • Skin protection. Lime is an alkali that can damage the skin of a person. When working, it is necessary to use tight gloves and other personal protective equipment. This disadvantage characterizes many building materials and solutions.

Should I use lime plaster?

The quality of construction and further construction work depend on the choice of finishing materials. It is necessary to select products for each individual case.

Inexperienced person is better contact a specialistdescribing all the features of the premises and the building as a whole. He will give recommendations on the choice of materials, quantity and manufacturer (there are a lot of them).