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Do-it-yourself mortar for plastering walls: proportions and subtleties of preparation 6 proven compositions
For several thousand years, plastering has confidently held the palm among others, including modern species wall decoration. Now there are high-quality ready-made mixtures, but their prices are high, so for large volumes developers prefer to use homemade mixtures. Let's take a detailed look at 6 time-tested recipes for preparing plaster mortars and compare them with factory versions.
Recipes for 6 types of plaster
Any plaster or masonry mortar consists of 3 main components - filler, binder and solvent. Everything is simple with a solvent; in all types of plaster, water is used as a solvent, the filler is river sand, But main secret quality lies in the choice of binder.
IN construction industry 2 types of sand are used - river and quarry. They differ in that quarry sand contains a significant percentage of clay, so this sand is not suitable for every solution.
Recipe No. 1: clay-based mixture
Clay sandy plaster mortar known since time immemorial. Now the clay composition in its pure form is rarely used, since performance characteristics he has low ones. The only tangible plus is affordable price, because you can dig up clay with your own hands, and sand is inexpensive.
If you plaster the façade with clay mortar, it will have to be repaired every year. Clay is more suitable for interior walls in dry rooms, but even here you should not expect special strength; every 3 to 4 years such finishing requires cosmetic repairs.
One of the few areas where clay mortar is actively used to this day is plastering and laying stoves.
The ratio of components in clay-sand mortar ranges from 1:3 to 1:5 (clay:sand). Here everything depends on the fat content of the clay; “skinny” clay uses less sand, and more is added to “fat” clay. Instructions for determining fat content are in the video below in this article, and we will talk about the rules for preparing clay plaster.
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Step #1. You can dig up clay with your own hands, and take it from a depth of 1 m, since there are fewer impurities there.
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Step #2.
The second step is soaking the dry clay. It is poured into a container and filled with water. The clay soaks from 3 to 20 days, and it is stirred every day. |
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Step #3.
When the clay is completely soaked, it is rubbed through a metal sieve to remove debris. As a result, you will get a composition similar to sour cream. |
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Step #4.
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Often cement, gypsum or slaked lime are added to the clay mortar. The choice of one or another binder component depends on the purpose of the room.
- Cement enhances the strength of the coating and increases the wall's resistance to moisture.
- Lime increases elasticity.
- Gypsum promotes quick setting, but this plaster does not tolerate wet environments.
Recipe No. 2: lime-gypsum mortar
Lime mortar with gypsum is interesting because it is prepared both in its pure form (lime-gypsum) and with the addition of sand. The presence of gypsum determines a number of rules that must be followed during preparation.
- To prepare the starting plaster, take 1 part of slaked lime and from 0.3 to 1 part of gypsum. Sand comes from 3 to 5 parts.
- The finishing composition is prepared either without sand at all, or no more than 2 parts of sand are added. If sand is not added, then the lime-gypsum mixture is prepared in a 1:1 ratio. When sand is added, the proportions change and are now 1:1.5:2 (lime-gypsum-sand).
- When working with gypsum solutions, you need to be especially careful about the cleanliness of containers and tools. If particles of the old mixture get into the new batch, it will harden one and a half times faster.
- When preparing the solution, water is first poured in, then gypsum is added to it, followed by lime and sand completes the list. In this case, the solution is constantly stirred.
Recipe No. 3: lime-sand mortar
Lime mortar is good if you plan to do a large amount of work in a dry room; if soaked, it can be stored for up to 3 days. It is best taken on brickwork or starting cement plaster. On wooden surfaces You can also throw it, but it is advisable to fill it with shingles (reinforcing mesh).
- For starting plaster, add from 2.5 to 4 parts of sand to 1 part of lime paste.
- The finishing composition is prepared either 1:1 or 1:2.
- During preparation, sifted sand is poured into a container with mixed lime in portions and mixed.
- When the solution reaches required viscosity It is advisable to rub it through a metal sieve, after which it is advisable to mix it again with a mixer and it can be applied. If the solution turns out to be thick, it is diluted with water.
- When wet, the composition has a grayish tint, but after drying the surface will become snow-white.
Recipe No. 4: cement-lime plaster
A mixture of lime and cement produces a composition that is universal in its characteristics. It can be used in both dry and wet areas. Moreover, this solution has high elasticity and is well suited for facade works. The setting time is up to 2 hours, so it can be prepared in large portions in a concrete mixer.
This composition is prepared in two ways:
- Sand and cement are mixed dry, after which liquid lime milk is added to the container and everything is thoroughly mixed in a concrete mixer or construction mixer.
- If you don’t have a concrete mixer at hand, then a construction mixer is more suitable next option: according to the recipe No. 3 described above, a lime-sand mortar is prepared, and at the end cement is added and everything is mixed with a mixer.
Recipe No. 5: cement-sand mortar
Cement mortar It is considered a classic, but its elasticity is lower than that of its limestone counterpart. However, this composition is excellent for finishing wet rooms, the basement of buildings and facades. Survival time is up to one and a half hours, the proportions are given below.
The scheme for preparing cement mortar is as follows:
- First, cement and sand are mixed dry; in this case, quarry sand can be used.
- Next, it is advisable to sift the dry mass through a metal construction sieve.
- Now with constant stirring it is added required amount water.
To increase plasticity, some craftsmen add a soap solution or liquid to the water. detergent for dishes. You should proceed from the calculation of 30 - 50 g. for 5 liters of water.
Recipe No. 6: terrasite solution
Behind the tricky name hides one of the species decorative plaster. Upon closer inspection, the main load-bearing composition here is the above-described cement-lime plaster. The decorative effect is achieved by adding marble, granite or other mineral chips and mica.
Color comes from a coloring pigment, so red lead is used to achieve red. green color chromium oxide will give, and burnt umber will give brown. Such compositions are fine-grained “M” (mineral filler up to 2 mm), medium-grained “C” (filler up to 4 mm) and coarse-grained “K” (up to 6 mm).
At the amateur level such decorative compositions It’s easier to put a “fur coat” on the façade. In the most affordable version, to throw on a fur coat you need a broom, a stick and a container with solution. Use a broom to “scoop up” the solution and hit it against a stick towards the wall. Splashes of plaster fly onto the wall, gradually splashing the entire facade.
What is added to plaster
In addition to river sand, several types of fillers can be added to cement-sand and cement-lime plaster mixtures. They are used both to improve decorative qualities and to increase performance characteristics.
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Quartz sand.
The range of sand is not limited to river and quarry types. Great importance has a fraction of sand grains, it ranges from tenths of a millimeter to 2.5 mm. For textured surfaces, a large fraction is taken, for smooth surfaces, a small fraction. |
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Special protection.
In large cities and nearby industrial enterprises Serpentinite or barite sand can be added to the plaster. These fillers partially block x-ray, electromagnetic and other types of radiation. |
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Marble chips.
Crumbs with a diameter of 1 - 4 mm are added to the plaster. Now this additive is actively used for arranging bark beetle cladding. To obtain a smooth marbled surface, plaster composition marble dust is added. But this technology requires lengthy grinding, so it is used only by professionals. |
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Mica.
There is an opinion that adding mica to the composition blocks the harmful effects of ultraviolet radiation on walls, but this is nothing more than an advertising ploy. In fact, mica gives a bright decorative effect, on a sunny day such a facade will shine with all the colors of the rainbow. |
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Foam chips.
When crumbly foam balls are added to the composition, the thermal insulation characteristics of the coating increase significantly. But the thickness of such plaster should be from 1.5 cm, plus it must be covered with some kind of finishing layer, since the decorative qualities of foam plastic in cement are not high. |
Subtleties of preparing solutions
In order for the plaster solution to adhere well, it must have an optimal consistency. Moreover, adding a lot of water is not an option; with this approach, the cladding will begin to crack as it dries. And too thick a composition will not adhere to vertical surfaces.
There is a popular way to check the readiness of plaster (in the photo the stages go from left to right):
- Run a trowel over the finished composition and see if “torn” grooves remain on it, then you need to add water to the solution.
- If after troweling the composition blurs and no traces remain, then it is too liquid, you need to add a dry mixture.
- The solution is considered ready if, after running a trowel over it, there are no breaks or grooves on the surface and does not change shape.
The use of liquid soap as a plasticizer is of course cheap way, but not the best quality. For getting good quality solution, a ready-made plasticizer is added to it, the proportions are indicated on the product packaging. Fortunately, you need very little of it and the price of such additives is relatively low.
Also, before plastering, the surface must be treated with primer a couple of times. In the case of homemade compositions, treating the walls with primer is mandatory, since, unlike factory mixtures, such plaster does not have additives that enhance adhesion.
Conclusion
Exact adherence to the above-described recipe and competent selection of components of plaster solutions will give good result. If you have any questions, write in the comments, I will try to help.
If you want to express gratitude, add a clarification or objection, or ask the author something - add a comment or say thank you!
The composition of plaster is known, if not to everyone, then to many. It would seem that there is nothing unusual in it, and its components are not in short supply. However, preparing the plaster mortar requires care and strict adherence to proportions, otherwise the mortar simply will not lie on the walls or after a short time will begin to crack and peel off from the surface. There are several types of plaster mixtures, each of which is used to perform specific work. The composition of the mortar for plastering indoor walls differs from that required to create a protective layer on external walls.
What is plaster
Plaster - facing material, rather rough, performing protective functions in relation to the surfaces of facade and interior walls. To prepare plaster mortar, various components and components, tools and technologies are used, but they strive to achieve one goal. This goal is to create a high-quality, durable, reliable coating on the walls of the building.
Before preparing a solution for plastering walls with your own hands, you will need to stock up on:
- The base most often used is cement. It is also called a binder, which ensures the strength of the finished mixture.
- The filler, which significantly increases the volume of the solution, creates a strong bond between the particles of the mixture.
- Liquid (of course water), which, when preparing a solution for plaster, is added in a strictly defined volume. Excess, as well as lack of moisture in the solution, will lead to its cracking and rapid destruction.
There are several types of compositions designed for plastering walls. Their main difference is the material used as a base, but in addition, each of these compositions is created to create a coating on certain surfaces.
Novice builders often think that preparing a mortar for plaster is simply mixing cement, sand and water, but to create a high-quality mixture and a truly durable coating on the walls, you need to strictly observe the proportions and take into account the possibility of introducing some additional components into the mortar.
So, for example, in some cases lime is added, despite the fact that this substance is not durable and, when dried, quickly crumbles and crumbles. As a component of a mortar for plastering walls, the proportions of which indicate that it is not necessary to add a certain amount of this white powder, lime is used as a means to increase the plasticity of the mortar. Gypsum hardens quickly and promotes rapid hardening of plaster mixtures.
Clay is a component without which it is impossible to imagine the process of plastering stoves. Its main distinguishing feature- strength gain after firing.
The main condition is precisely observed proportions for the plaster. But no less important right choice the basis of the mixture and various components, depending on the operating conditions of the created coating.
Cement mortar
Cement mortar for plaster is the most in demand and popular when performing various works related to the rough finishing of the building walls. Its main advantage is its high level of strength. To obtain a high-quality mixture, it is important to know not only how to dilute cement for plaster, but also what components and in what quantities should be present in the solution.
How to make mortar for plaster from cement? Will need to cook exact amount each of the required components. First of all we're talking about directly about cement. Depending on what qualities the prepared solution should have, the brand of cement is chosen. For plastering the external walls of a building, cement grades M 200 - M 300 are most often used. The mixture prepared on the basis of such a binder will differ high level strength and is suitable for creating a rough finishing coating on the facade of a building.
Correctly observed proportions of cement mortar for plaster are of great importance:
- cement grade M 300 - 1 part;
- fine sifted sand - 3 parts;
- water is added in such a volume that the resulting mixture resembles thick sour cream.
The amount of water depends on the moisture content of the sand, so it is impossible to indicate the exact number of buckets used in preparing the cement-sand mixture.
A solution for plastering walls, consisting of cement, sand and water, contains only one binder (cement), and therefore is one of the simple ones. Complex or multicomponent mixtures are those that contain two or more binder components. An important condition for preparing a high-quality plastering solution is the refusal to add any components during the mixing process.
Before making a mortar for cement plaster, you will need to prepare a container in which you can freely mix all the components. First, cement and sand are poured there, both components are mixed and filled with water, introducing it into the solution gradually and achieving the desired consistency of the mixture.
An important characteristic is the fat content of the solution, which can be determined by how the composition behaves on a trowel:
- Sticks to the tool - high fat content and to create high-quality coating does not need to be added to the solution a large number of filler.
- It does not stay on the trowel - the solution is thin, the situation can be corrected by adding a binder.
The ratio of filler and binder is correct if, after manual mixing, a thin layer of mortar remains on the trowel.
Lime
The composition of lime mortar for plaster is similar in proportions to cement-based mortar. To prepare the mixture you will need directly lime and sand in a ratio of 1:3.
Before making lime mortar for plaster, you need to prepare lime dough separately in advance. Lime in its pure form is not added to the solution.
Cement-lime mortar for plaster to 10 parts of cement add 4 parts of lime and 30 (or 50) parts of sand. This is the most high-quality composition for applying the first layer of plaster (spray). For the second layer, cement and lime paste are taken in equal parts, and for the third - 1.5 times more lime than cement.
Due to the addition of lime paste, the time for complete hardening of such a mixture increases by two days, but at the same time the level of strength of the finished coating also increases. Before making a solution for plastering walls with the addition of quicklime, the powder must be filled with water and left for at least 14 days. The extinguishing process is quite lengthy, and failure to comply with the technology leads to the creation of a low-quality mixture, which, after complete drying, begins to crack and fall off the surface.
The process of preparing the solution requires first of all mixing the dry ingredients, then adding lime paste and only after that adding water, constantly mixing all the components of the solution until homogeneous mixture. There should be no lumps in the resulting solution.
Preparation of lime mortar for plaster begins with adding a small amount of sand to the prepared lime dough. The amount of clean sifted sand should be at least 3 parts to 1 part slaked lime. After thoroughly mixing the components, begin to gradually add water.
Gypsum and clay plaster
Gypsum mortar for plaster is not particularly durable; it does not tolerate the destructive effects of moisture and therefore is usually used for indoor work. You can increase the level of its strength by adding a little cement to the solution. Before preparing gypsum-based plaster, the content of sand and cement in the solution is calculated.
Gypsum plaster hardens quickly on the treated surface, so this solution is used by professionals or people who have certain experience and skills in working with such compositions.
Before starting work, the entire surface of the wall is divided into sections, the area of each of which does not exceed 1 m2.
This action is necessary because this plastering mixture has a minimal drying time. When starting to prepare the solution, first mix sand and lime or cement, and then mix building gypsum (alabaster) with a large amount of water in a separate container. Now gradually add the gypsum mixture to cement with sand or lime paste mixed with sand.
Clay plaster is prepared on the basis of alumina, which is pre-soaked in water. The required amount of material is poured with water so that it completely covers the alumina and left for at least 5-6 hours to swell. The softened clay is thoroughly mixed and three times more sand is added to it. The main condition is the gradual addition of all components of the mixture and constant thorough mixing of the composition. If a pure clay solution is used for plastering stoves, then after final mixing it can be immediately applied to the surface.
For working on walls adobe houses use clay plaster with the addition of lime, building gypsum or cement:
- lime dough - 1 part;
- soft clay - 2 parts;
- sifted sand - 6 parts.
This solution can be used to plaster inner surface walls In the case when plastering will be carried out outside the building, mix:
- 10 kg of cement;
- 2 kg of clay;
- 30 kg of clean sand.
Water is added gradually, monitoring the consistency of the mixture. When using stucco, you need to be very careful. Clay plaster with the addition of alabaster hardens in 5 minutes and dries completely in half an hour. That is why the solution is prepared in small portions, applied to small areas surfaces, add alabaster no more than ¼ of the amount of clay. You can learn in detail about the intricacies of the process of preparing mortar for plaster with your own hands by watching the video.
Preparing a solution for plaster with your own hands is not so difficult, but we must not forget about the need to comply with all the rules and regulations regarding the materials used. The sequence of work and the established proportions must not be violated. Only in this case, all the manipulations performed will achieve a positive result.
Cement-sand mortar, which is used to level walls and prepare for finishing, has many advantages.
Being budget option for repair work, it can even serve finishing coat for external walls. In order to properly perform plastering, you need to study the composition of the cement mortar for plastering walls and find out how to prepare cement-sand mortar for plastering walls with your own hands.
A little about the mixture
Today we will not only find out everything about cement mortar for plastering walls, the proportions of its production and the characteristics of the material, but also get acquainted with other popular plaster mortars. First of all, it is worth noting that plaster solutions are necessary for leveling the bases and preparing them both inside and outside the house. At the same time, for the street the mixture must be moisture-resistant, frost-resistant and resistant to sudden changes temperature indicators, and for the interior it is plastic and environmentally friendly.
Plaster can be applied to concrete, wood, metal bases, as well as gypsum plasterboard, foam concrete or brick. In this case, you should start from the characteristics of the base and their adhesion to the solution. In the table you can see the most popular combinations of mixtures for surface treatment and their proportions in parts:
Cement plaster is usually used for wet rooms, facades, plinths and the foundation part on which the house stands. Various additives improve the characteristics of the material and make it insulating. A simple homemade recipe and ease of application makes it possible to treat a larger area. In addition, you can mechanize the process of spraying on the wall.
Important! The costs of purchasing components and preparing the solution yourself will be minimal.
Mixing mortar for plaster (video)
Preparing the mixture
Making cement plaster yourself involves mixing all the necessary components and adding plasticizers to improve the quality of the mixture. The use of sand as a filler is traditional. Such a solution acquires the properties of strength and resistance to cracking, which is so necessary for the surface.
Important! All ingredients are important for the mixture, so when choosing cement, base it on its brand. Higher grade means better strength.
Let's find out how to properly make cement mortar for plastering walls yourself and learn tips from professionals:
- A novice master has no idea what cement brands mean. Therefore, when choosing them, proceed from the specifics of your work. At ordinary plaster the wall will do M400, for work spaces, garages and where you need to save money, choose M300, but for the basement of a building and places with high humidity you should buy Portland cement M500
- The mixture begins to dry within 10-15 minutes after application to the base, so there is no need to hesitate when spraying and smoothing. It will take 10 to 12 hours for the plaster to dry completely. If you want to maximize the strength of the plastered wall, then you will need to exclude all additional finishing and mechanical influences for about a month
- You need to choose the right sand fraction for cement mortar - it can be from 0.2 to 0.5 mm and from 0.5-2 mm. Make sure that there is no organic impurity in the sand, otherwise it will cause rotting in the future
Table of proportions depending on the brand of cement:
| Cement brands | Brands of solution | ||||
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| 200 | 150 | 100 | 75 | 50 | |
| 300 | - | 1:2,5:0,1 | 1:3,5:0,2 | 1:4:0,3 | 1:6:0,6 |
| 400 | 1:2,5:0,1 | 1:3:0,2 | 1:4,5:0,4 | 1:5,5:0,5 | 1:8:0,9 |
| 500 | 1:3:0,2 | 1:4:0,3 | 1:5,5:0,5 | 1:7:0,8 | - |
Important! Using online calculator it will be easier for you to calculate required quantity mixtures for treating wall surfaces. And with the help of the video, every beginner will learn the sequence of mixing plaster.
Most people are interested in how long it will take for cement plaster to dry on a wall? First of all, the drying process depends on the ambient temperature - for interior spaces It is prohibited to use artificial drying and allow drafts. For external walls It will take about 24 hours to dry, but the strength indicators will gain strength about a month after finishing. In what order to cook cement plasters and how to make the right solution yourself:
- The main components in dry form must be taken in equal parts, then mix them well together
- To improve the quality of the plaster, it is necessary to sift the resulting mixture through a sieve.
- On next stage water is added to the mixture - the resulting solution should be homogeneous
- Cement plasters are not plastic, so there is one trick in which washing liquids are added to the plasters at the rate of 30-50 ml per 5 liters of water
Plastering process
To carry out high-quality repair work, you should have at least minimal plastering skills. Therefore, let's look at the features of plastering walls with cement mortar using beacons:
- For rooms, for example, in the bathroom, where you need to glue tiles, you need to achieve perfectly smooth walls, you should use beacons. The cost of such work will be slightly higher, since the purchase of metal beacons will be required
- First of all, it is necessary to install the outer beacons, which will be located at a distance of about 20-25 cm from the corner of the room. The strips should be fixed with plaster mortar cakes, which are 40 cm apart from each other.
- The next metal beacon is pressed tightly against the guides and checked building level. Further between vertical stripes a fishing line or rope is pulled, thanks to which the fastening of subsequent beacons is controlled
- Don't forget to use a small ladle to spray the solution - more experienced craftsmen For this purpose, spatulas are used, which can be used to immediately level the surface
- After treating the entire surface, let it dry and then remove the metal beacons. They should be picked out only after the solution has set. The resulting voids should be plastered with finishing putty or plaster mortar for leveling
- When plastering brick walls cement mortar, it is good to use a reinforcing mesh, which is fixed with cement mortar. The liquid should have a dense consistency. For one square meter At least 8 fixation points must be used
Important! With high-quality leveling, the wall will last for many years, it will not crack or crumble.
Mechanical Leveling Options
For those who are not confident in their ability to plaster with cement mixtures, they are interested in how it is done mechanized plaster cement walls sand mortar and what is the price for carrying out this work. It should be noted right away that many craftsmen charge for 1m2 of space, and the total amount depends on the area of the entire room.
The machine method of finishing surfaces significantly speeds up the speed of all repair work. The elastic mortar is thrown onto the wall using a hopper - it makes it possible to increase productivity. The table shows the average prices for professional plaster:
| Name | Prices per m2 |
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| Plaster without mesh | From 450 rub. |
| Plaster on mesh | From 550 rub. |
| Arched slopes | From 660 rubles per linear meter |
| Plastering wall surfaces on beacons |
Plastering walls is not an easy task. The quality of the finishing of the walls directly depends on it. If you decide to do this work yourself, then we will tell you how to prepare a solution for plaster, the proportions of which must be strictly observed. Otherwise, you may not end up with a smooth, even and durable surface, but rather a loose, porous layer of mortar, ready to fall off at any moment.
In the article we will answer questions about the composition and proportions of the mixture based on various components, talk about the requirements for plaster solutions, as well as the types of various modifying additives.
Buy a ready-made mixture or make it yourself
In this matter main role plays the finishing area, as well as physical and financial opportunities owners.
- Ready plaster mixture.
The composition, in addition to the main selected and high-quality components (cement, sand), includes many special additives - modifiers, plasticizers that improve the working and performance qualities of the plaster.
But the price of such a mixture is much higher than that of a solution prepared by yourself. Therefore, it is unprofitable to use ready-made plaster over a large area. But if you need to finish small surface, then it’s better to buy ready-made composition. You don’t have to buy all the components separately, charge the mortar mixer, and it will take less time.
- Do-it-yourself plaster mixture.
When it comes to finishing a large brick or foam block house, to reduce the cost of work, owners usually prefer to prepare the plaster mixture themselves. Cement and sand are bought, a small mortar mixer is installed, and little by little, in portions, the solution is prepared.
In this case, you have to work with your hands and spend some personal time. But as they say, “your own work doesn’t count.”
When working independently, it is necessary to strictly observe the proportions of the solution for plastering walls, otherwise there is a risk of redoing the entire work already at the application stage. It’s even worse if a low-quality solution begins to fall off at the finishing stage.
Such defects can be corrected only by completely removing the applied plaster and replacing it with a new layer. And this, as you understand, is an additional and considerable expense.
Types of cement mortar, requirements, proportions
There are few types of mixtures, but each requires separate consideration, as it has its own unique characteristics. They differ in the presence of various additional components in the solution.
So, the plaster mixture can be:
Used for leveling and finishing. This mixture is compatible with any rough surfaces, except concrete, due to its weak adhesion to the latter.
This mixture is used mainly to make rough plaster; for finishing, very fine sand is needed. The mixture remains “alive” for an hour, after which technical specifications are getting worse.
- Lime-cement.
Used for finishing brick or concrete surfaces. Lime gives the mortar plasticity, which makes it easier to apply and stretch. The vapor permeability and strength of the solution also increases, and the “survival” of the mixture is extended to 3 hours.
In addition, lime has bactericidal properties; mold will never form on walls covered with lime mortar, and fungi and microorganisms will not appear. But the proportions of lime mortar for plaster must be observed in order to avoid the appearance of lime stains on the walls.
Lime “efflorescence” will bring a lot of trouble during finishing, since not all paints or putties are compatible with this material.
- Gypsum-cement.
Used for improved plastering of walls. Gives an even, durable layer that is easy to sand. It sets quickly, so it is not recommended to prepare a large amount of solution at once.
If it is necessary to prepare a lot of solution, then retarders are used to extend the “life” plaster mixture. IN ready-made mixtures they are already present.
Important! In mixtures prepared independently, depending on the air temperature, the type and quality of the surface, and the type of room, it is necessary to add special components. Correctly selected mineral fillers, polymer additives or plasticizers will make the solution more plastic, frost- or heat-resistant, and enhance adhesive and astringent properties.
Cement-sand and lime mortars are used for internal or external walls (see How plastering of external walls is done) exposed to moisture; gypsum-cement mixtures are used only for interior work in dry rooms.
Requirements for solution components
The composition of any plaster mortar includes three main components: cement, sand and water. The strength and durability of the applied layer, as well as the quality of grinding and subsequent finishing, directly depend on their quality.
So:
- Cement.
- This is a binding component that plays a major role in the formation and hardening of the solution, giving the mixture strength and water resistance.
- The proportions for preparing the plaster mortar are standard. It is recommended to use Portland cement or Portland slag cement no lower than M300.
- It depends on the brand what proportions of cement and sand will need to be taken for plastering: the higher the brand, the more parts of sand you need to add per unit of cement.
- This material also has a shelf life; the fresher the cement, the better characteristics. It is advisable to purchase it in paper bags and store it in a dry place.
Cement is not afraid of frost, but high humidity The hardening process may begin right in the package.
- Sand.
This material is the filler of the plaster mixture; it determines the strength, weight, thermal conductivity and density of the solution.
- When interacting with cement, sand creates a monolithic layer with the properties of solid rock.
- For rough plaster, use fine-grained ravine sand, in which a small presence of clay is allowed.
- If there is a lot of impurity, the solution can settle and separate. It will have to be constantly stirred, and it will still be difficult to work with, since the ability of the mixture to stick and level is reduced.
For an improved layer, river sand is best suited - or ordinary, but clean, sifted through a fine sieve, washed to remove impurities. And again, we must not forget about the proportions - cement-lime plaster will turn out more High Quality, if the sand in it does not contain clay impurities, and the amount of filler does not exceed the required volume.
- Water.
- The liquid for the solution must be clean, free from oil, various organic and chemical pollution, garbage.
- All impurities after the liquid evaporates will remain in the solution and can significantly affect the quality of further finishing.
- Oil stains will appear through the plaster or wallpaper, and the paint in this area will peel off. The same thing can happen from the presence of chemical impurities. Therefore, experts recommend using clean, preferably drinking water.
- When mixing with water, the cement setting process begins in the plaster mixture, so after mixing, the solution must be worked out within 1 hour.
Longer storage of the mixture reduces specifications material, and complicates the work.
Proportions of components for different types of solution
Any instruction requires strict adherence to the proportions of cement and sand for plastering walls, so that the work is quick and enjoyable, and the result is durable and reliable.
If there are no plasticizing additives, then to improve the plastic properties of the solution, craftsmen advise adding a little neutral liquid soap or soap solution:
- In a cement-sand mixture, the composition of the main components should be as follows:
| Cement brand | Cement/sand, parts | Produced brand of solution |
| M300 | 1/3,5 | M100 |
| 1/2,5 | M150 | |
| M400 | 1/4,5 | M100 |
| 1/3 | M150 | |
| M500 | 1/5,5 | M100 |
| 1/4 | M150 |
Water is added to the mixture gradually, with constant stirring. The solution is brought to the consistency of thick sour cream.
Important! A solution that is too plastic will lie unevenly on the wall, drain, and when leveling it will begin to drag on the tool. The hard mixture will stick to the trowel, making it difficult to spread, and when it dries, it will shrink and crack. You can recognize a normal solution by dipping a trowel; the mixture should leave a thin layer on it without sticking lumps.
- Lime mortar for plaster, proportions:
| Cement brand | Cement/lime/sand, parts | Produced brand of solution |
| 1/0,3/4 | M75 | |
| 1/0,2/3,5 | M100 | |
| 1/0,1/2,5 | M150 | |
| 1/0,5/5,5 | M75 | |
| 1/0,4/4,5 | M100 | |
| 1/0,2/3 | M150 | |
| 1/0,8/7 | M75 | |
| 1/0,5/5,5 | M100 | |
| 1/0,3/4 | M150 |
When cement-lime plaster is used for finishing, the proportions of lime in the mortar are small, so it is better to purchase ready-made lime paste from hardware store. It is quite problematic to prepare the required component with your own hands; the slaking and curing time for lime is about a month using a special technology.
An incorrectly prepared or unripened mass can destroy the plaster mortar and reduce all work to zero.
Modifying additives
Separately, we need to talk about additives in the plaster mortar; with them, the mixture will acquire some important properties necessary both for the application and treatment of surfaces, and for their further operation.
Here, too, it is important to maintain the proportions for plastering the walls: on each package there is detailed instructions on the use of the supplement, and it must be strictly followed:
- Accelerators or retarders.
These are components that act on the crystal lattice of the binder and regulate the time of its formation (setting).
It is advisable to add them, for example, to a gypsum-cement mixture to prolong its “survivability.” In this case, casein or bone glue serves as such an additive.
- Additives to increase plasticity.
When these substances enter the solution with water, they form many bubbles, due to which the liquid evaporates less and is absorbed into the surface, which means it stays in the mixture much longer. They are recommended for use for simple, traditional cement-sand mortars, which quickly lose water and delaminate.
- Antifreeze additives.
Basically, it includes various special salts that slow down and even prevent freezing of water in the solution for some time, and therefore reduce the risk of loss positive qualities mixtures when the air temperature drops.
It must be said that they operate mainly down to -5 degrees. At lower temperatures, plastering work cannot be carried out; no additives will save the mixture from freezing.
- Additives to increase strength.
They can be of two types: some work in tandem with a binder, by chemical exposure increase its properties; others act independently, personally performing a reinforcing function.
The second type is called fiber, which can consist of waste from glass, pulp or metal production. Fiber is sold in the form of small chips or polymer threads, which, when dropped into the solution, intertwine and give the plaster additional strength.
Conclusion
If the surface of the walls is not too smooth, no need to be upset - that’s it minor irregularities will hide finishing putty. The main thing is that the plaster itself is durable, does not crumble, crack or fall off.
By correctly determining the composition and calculating the proportions of the plaster mortar, you will receive a high-quality and durable coating that will not require repairs for many years. And after looking at the photos and videos in this article, you will get answers to other questions that concern you.
But if you are still not confident in your abilities, and do not risk plastering the walls yourself, then we recommend inviting specialists who will do this work quickly, beautifully and efficiently.
The quality and durability of the entire finish, including the finishing one, which will be carried out on the plaster layer, depends on how correctly the plaster solution is selected and prepared for use indoors or outdoors.
Probably, it does not seem new and everyone has long known that modern plaster mortars using new technologies are produced from dry building mixtures, which are mixed with the amount of water specified by the manufacturer, l/1 kg of dry mixture.
Yes, such mixtures are popular, since they can be used to get the job done quickly and efficiently, but plastering a house with such compositions is not a cheap undertaking. The fact is that in terms of price they are several times, or even tens of times, more expensive than traditional compositions due to the presence of all kinds of modifiers, plasticizers and high-quality, selected fillers.
So if the construction budget is small, then perhaps it makes sense to use good old cement or lime plaster mortars. Therefore, in this article we will consider traditional solutions, or rather the composition of the solution for plastering works, which contains a list of components:
- astringent;
- filler;
- modifying additives.
The composition of the plaster solution may depend on many factors, since each component has certain properties, such as: strength, water resistance, frost resistance, setting speed, plasticity, and so on.
Among the factors influencing the selection of components for the plaster mortar are the type of surface, the purpose of the room and the amount of money for plaster, in the end.
Types of binders included in the mortar for plaster, proportions of mortar for plaster
The binder for a plaster mortar is a component on which almost everything depends: strength, water resistance, setting speed and, partly, plasticity.
For example, the composition of a cement-based plaster mortar has the highest degree of strength and water resistance compared to lime mortar, which, unlike the first, is used only for plastering walls inside residential premises. But lime mortar is more plastic and therefore easier to work with.
There are also solutions that contain two binders, for example cement-lime or lime-gypsum mortars, which are called complex mortars. To clarify, let’s make a list of binder components that are included in the plaster solution:
- cement;
- lime;
- gypsum.
In this case, the list of binders is small; these are all its types, which are used in the preparation of both modern dry construction mixtures for plaster mortars, and in the preparation of traditional compositions, the proportions of which we will consider below for each individual binder.
Cement binder
considered the most durable and waterproof.
It is used in the production of cement-sand and cement-lime plaster mortars, which are used for finishing walls inside and outside.
There are varieties of cements, such as Portland cement and Portland slag cement, which are most often used in plaster mortars; There are also pozzolanic varieties, including fast-hardening ones.
It is important what brand of cement is used, for example, if you take cement of the M400 brand, then for 1 such bag you will need four bags of sand for plaster mortars (or other appropriate fine-grained filler) in order for the mortar grade to be M100.
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Cement brand |
The ratio of cement: lime: sand and the grade of mortar produced |
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If you take the M500 brand, then it will require five parts of the corresponding filler for the M100 brand of solution. A corresponding proportion is observed in the production of cement-lime mortars.
has special properties, the main one of which is bactericidal.
Lime prevents the development of microorganisms even decades after application.
Lime-based solutions are plastic, adhere well to the wall and are easy to level, and can also be grouted.
There are two main types of it - hydraulic and air. Hydraulic lime is less plastic, therefore, it is more difficult to work with such a solution, but it is stronger after setting, and it sets faster than air lime.
As for the proportion of the plaster solution, it depends on the type of lime (there are only three), as well as its condition (ground boiling water or lime paste). Today, ready-packed lime dough is mostly used for the production of lime, lime-gypsum and cement-lime mortars for plaster.
Even more often you can find ready-made lime mortars packaged in plastic bags, due to the ability of such a solution not to set for a very long time.
has the best plasticity and differs from the previous ones in its almost lightning fast setting speed.
There are many varieties of it according to the specifications ( technical specifications), but when it comes to the use of gypsum binder for plastering work, then this is the grade of gypsum G-2, G-3, G-4, G-5 with fine, medium or coarse grinding (grain size), which is called building gypsum.
These brands of building gypsum belong to groups of the first and second gypsum binders. The first group is produced by heat treatment of gypsum raw materials with low, medium and high degrees of firing.
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Material |
Plaster thickness, cm |
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Lime mortar, l |
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The second category includes materials that are produced using technology that does not involve firing. The calcined gypsum binder used to make plaster mortar is marked PG.
Types of fillers included in the mortar for plaster
The filler for the plaster mortar determines its qualities such as weight, strength, thermal conductivity and decorativeness.
Fillers with different properties and grain sizes are used for ordinary, special and decorative plasters.
For ordinary plaster, as a rule, it is sand; for special plaster, the range of fillers is much wider; for decorative plaster, ground types of semi-precious stones are used. In addition, they may contain impurities; The grains themselves can be of different shapes and have different densities and much more. Let's look at the types of fillers for plaster mortars, their list is as follows:
- sand for ordinary plasters;
- sand for special plasters;
- sand for decorative plasters;
- active mineral fillers.
As a rule, fillers for plaster mortars are prepared in advance, sifted in production or directly on construction site, where the work of preparing the plaster mixture takes place. Let's take a closer look at each of the data in the list of fillers.
Sand for ordinary plasters
- this is fine-grained (fine-grained) stone material, which with the help binder material forms a solid artificial stone with similar properties.
For the plaster mortar, take gully or quarry sand with a fraction of up to 5 mm, which contains a minimal admixture of clay or no clay at all; The grains themselves have a sharp shape, which provides better dressing.
However, there are cases when gully sand is not acceptable - when plastering facades, when the absence of clay impurities is required. At the same time, the composition of the solution for facade plaster contains a filler - river sand, and modern additives are used to improve plasticity. Plaster with such a filler does not have any special qualities, neither decorative nor special.
Sand for special plasters
has special properties. Thus, serpenite and barite sands with a grain fraction of more than 1.25 mm and a density of 2400 kg/m3 are used as fillers for X-ray protective plasters.
Quartz sand and diabase flour are fillers for acid-resistant plasters. Metal shavings and dust are used as fillers for impact-resistant plaster.
There are also fillers that have a high thermal insulation effect, such as perlite sand, which is part of the solution for thermal insulation plaster.
Sand for decorative plasters
can be very different. This can be a mineral filler of a fraction of 1.5-4 mm for modern so-called “facade” decorative plasters.
There is a finer filler than sand - granite and marble flour, as well as other ground decorative and semi-precious stones.
The composition of the solution for decorative plaster can contain several different fillers, including decorative and ordinary fillers. There may also be pigments that give the solution a particular color, for example, construction black, which is also considered a filler for solutions.
Active mineral fillers
are substances of natural origin that not only create the volume of the solution, but also participate in the process of formation of the crystal lattice, which occurs when the solution sets.
These substances act like an astringent component, enhancing its effect and, accordingly, increasing the grade of the solution.
They can be of natural origin (sedimentary and volcanic) and artificial. Natural sedimentary rocks are diatomites, tripoli, opoka, gliezhi; natural volcanic - trails, tuffs, ash, pumice; artificial - siliceous waste, burnt clay, fuel waste.
Types of modifying additives included in the plaster solution
Modifying additives for plaster mortar are used to improve its qualities. There are universal and highly targeted modifiers.
Their method of action mainly comes down to interaction with the binder (cement) and the enhancement of certain of its properties.
But there is another type of additives - filler additives, which themselves are not chemically active, but have a certain form, strength and other geometric and mechanical qualities, respectively improve the strength of the plaster itself. Regarding their functions in the solution, modifiers for plasters are divided into the following types:
- accelerators/retarders;
- additives to improve frost resistance;
- additives to improve plasticity;
- strength/grade additives.
This list contains additives of both old and new types. They can be presented in the form of bulk or liquid materials, which are mixed with water in advance, or poured directly into the container when preparing the composition for plaster. Next, we will consider these components in more detail and describe their principle of operation.
Set accelerators/retarders
- these are substances that, through chemical action, slow down (or accelerate) the ability of the binder component in the plaster to form a crystalline network (the ability to set).
For example, the composition of a gypsum mortar for plaster depends on the presence of a set retarder; in this case, bone or casein glue acts as a classic retarder.
It is clear that today these supplements are presented as complex chemical substances, having complex mechanisms of influence on the binder, allowing to achieve the desired result.
Additives to improve frost resistance
existed before and still exist.
On a par with ferric chloride In the overwhelming majority of the market you can find modern, harmless additives based on special salts. These additives dissolve in water, which is used to mix the dry mixture of binder with filler.
Their essence is to prevent the water itself from freezing under the influence of negative temperatures. It is difficult to explain the principle of operation, but everyone knows that salt water freezes much more difficult than fresh water, therefore the most basic types of these additives are presented as salts.
Additives to improve plasticity
very desirable for use in plaster mortars made using traditional technologies.
This is especially true for simple cement-sand mortar for plaster, which is very difficult to work with due to the very rapid loss of water from it, as well as its separation into water and other components.
The essence of such additives is to retain most of the water in the solution and prevent it from separating. Getting into the water and shaking with all the components of the solution, this additive creates many small bubbles in which the water is retained for some time.
Strength Additives
/brands of mortar can act both in conjunction with the binder and separately. In the second case, from a technical point of view, they themselves are binders, however, their properties are not enough for self-use without main binder.
In addition, there are individual additives that are not chemically active (do not participate in the formation of the crystalline network), but are used as a durable filler (reinforcing additives).
This is the so-called waste from metal, glass or cellulose production, presented in the form of small shavings or threads, which, when added to the mixture, intertwine with each other, reinforcing (strengthening) the structure of the finished plaster layer.
