How to make cement mortar for plastering walls. Preparing cement mortar for plaster

The durability of the plaster both inside and outside the building depends on the quality of the prepared mortar, no matter what type it is. All modern plaster solutions are made from dry mixtures. They are mixed with water in a certain amount of proportions, which is indicated on the packaging. These mixtures are convenient to use, but work with their use is not cheap. This is explained by the presence of modifiers, plasticizers and fillers in their composition. A regular solution, prepared by yourself, is much cheaper, and its quality is no worse than store-bought.

Proportions for preparing the solution yourself

The main component is a binder. This role is played by cement, lime, gypsum or clay. The latter material is rarely used. To the selected binder you need to add a filler - sand. And these two ingredients are diluted with water to the desired consistency. Their ratio depends on the characteristics that need to be obtained.

The fat content of the solution plays an important role. It must be especially maintained when dealing with clay and lime compounds. Based on its indicator, you can determine whether there is enough binder in the mixture or not.. Depending on this, solutions are divided into fatty and lean. For facing works It is better that the mixture is normal. This is determined by its fluidity and setting.

If the composition sticks when stirred, then it is fatty; otherwise, it is thin. Adding a binder or diluting with water will help bring it to normal.

Finishing with thin plaster at speed can lead to cracking of the base. In addition, it does not adhere well to surfaces. Its oily consistency can cause excessive shrinkage and, when drying, deep cracks will appear on its surface.

The video shows the preparation of plaster mortar:

Kneading:

the prepared materials are sifted through a sieve. It can be with cells 3x3 and 5x5 mm;
It is better to prepare the solution in a special box, up to 20 mm high;
All components are mixed one by one in the indicated proportions using a wooden paddle, the length of which is about a meter. The resulting mixture must be homogeneous, otherwise it will affect its adhesion;
After receiving the solution, it should be checked for fat content. This is done simply: the paddle is inserted into the resulting mixture; if, when it is removed, a little mixture remains on it, then it is prepared correctly. If there is strong sticking, filler must be added, and if the mixture does not stick to the surface of the oar, then a binder is added to it.

The video shows the proportions for the plaster mortar:

When choosing a type of composition for plaster, it is necessary to take into account the material of the surface on which it will be applied:

external stone and concrete facades require the use of Portland cement and Portland slag cement as binders;
wood and plaster surfaces they are forced to use combined lime mixtures, which contain, in addition to the main binder, clay or gypsum;
cement and stone walls indoors they interact well with solutions based on lime and cement; they can also consist of different types of binders.

Types of mixture and classification

Maintaining the correct ratios of the components included in the mixture is the main requirement for plaster solutions. Their meaning depends on the selected material. All solutions are divided into types and are called the main binder component. :

Lime plaster

It differs from all other compositions in its bactericidal properties; even many years after use, it will prevent the development of microorganisms on its surface.

There are two types of such a solution: air and hydraulic. They both have good plasticity, are perfectly applied to the surface and leveled. After their application, you can fine-tune the surface in the form of grinding, either manually or using a special device. The main difference between these two types of lime composition is the degree of plasticity and setting time. Hydraulic lime mortar adheres stronger and faster to the surface than air mortar, but the latter is easier to work with, since it is the most plastic.

The proportions of the lime composition depend on the type of lime and its condition (loose or compacted). The most commonly used portions of building materials are:

1 part cement;
3-5 parts of sifted sand;
a little liquid detergent;
one part lime mixture, or rather the test.

In the video - lime plaster mortar:

The last component is prepared from lime and water in proportions 1:3. The liquid should be slightly warmed before use to cause it to react with the lime component. All the lime is poured into the prepared container for the solution and filled with half the specified volume of water. After the reaction has passed, the rest of it is added, the components are mixed, and left to mature for a day. It is better to choose a container with a lid for these purposes.

After 24 hours of exposure, the composition is diluted to a liquid state and poured into a previously prepared hole, into which sifted sand is then added, and earth is poured on top of it. The total height of the earth-sand mixture is half a meter.

The resulting composition is aged in a pit for 15-20 days. After this, the resulting lime paste is ready for use, and it is added to the solution to create plaster.

How to cook:

lime paste is poured into the prepared box;
then cement and a small part of water are introduced into it. The mass is kneaded until smooth; there should be no lumps in it;
sand and the rest of the water and a little liquid soap are added. It acts as a plasticizer and serves to give the composition even greater plasticity.
the resulting mass is checked for fat content, if it is the desired type, then you can apply plaster.

Lime mortars must be used within 24 hours after their preparation.

Sand-cement composition

This solution is the most used, it is strong and waterproof. It can be used as for the interior surfaces of the house.

There are several types of cement, the most commonly used are fast-hardening types. The ratio of components included in the solution depends on the brand and selected cement. If an M 400 bag is used, then you need to take 4 bags of sand to get the right brand M 100. In the case of using M 500, it is necessary to take five times more filler.

Due to these features of this material, on average one part of cement takes:

3-5 servings of sifted sand;
water, how much the composition will absorb until the desired mass is obtained;
a little detergent.

It is worth considering that plasticity depends on the sand content. Solutions with less of it are labor-intensive to work with, as they do not spread well.

Step-by-step preparation:

First, sand is poured into the box;
then it is sprinkled with cement and the components are thoroughly mixed together;
Water is added with constant stirring. It must be added until a creamy solution is obtained;
The last step is to introduce liquid soap and PVA glue, which will ensure rapid adhesion of the material to the surface.

The video shows a plastering station for sand-cement mortar:

The prepared composition must be used within an hour, after this time it will lose its properties and subsequently will not hold up well. Based on this, it is advisable to mix cement mixture in small portions so that you can use it completely in one go.

Lime-gypsum

Gypsum differs from other binders in its ultra-fast setting ability. For plastering works Its grades G3-5 are used, which can be of three different grinds:

Their division depends on the grain size; the limits of the values of each of the subgroups are specified in the technical specifications for this material. For plastering, building gypsum with any grain structure is used.

The grades of gypsum material used can be produced in two ways:

with help heat treatment followed by annealing;
without annealing, they are produced using new technologies.

Before diluting such a solution, it is necessary to carry out all preparatory work and use it immediately after kneading.

Step-by-step preparation:

prepare one share of gypsum (alabaster) and three times as much lime paste;
combine gypsum with water to form thick sour cream;
add the lime component to the resulting mixture and mix.

The resulting composition sets very quickly, so it must be used quickly, only five minutes are allotted for this. Complete hardening of the solution occurs after half an hour. you can read what gypsum plaster considered the best.

In the video - “build not rebuild” about plaster mortars:

Features of using plasticizer

To improve the quality of the solution, various modifiers and plasticizers are used. Their effect is reduced to enhancing the properties of the binder component.

Plasticizers improve the elasticity and plasticity of the main component of the plaster solution. With their help, laying the material is easier and you can achieve a more even surface. In cement mortars they prevent shrinkage. In addition, they do not allow water to escape from the fresh solution, and thus extend the period of its application, and after the material dries, they prevent cracking.

Sometimes it is used instead of building lime; it performs well when added to a cement-sand mixture, and does not have the disadvantages of the lime component. Thanks to the plasticizer cement mortar adheres better to the surface being treated, work with ready-made composition possible longer than with its analogue without plasticizer.

The video shows a plasticizer for plaster mortar:

Wall cladding – important stage construction work. If you choose the wrong solution or do not maintain its proportions, then over time cracks will form on the surface, which will soon become noticeable on the surface. decorative layer. It turns out that the strength and durability of the plaster depends entirely on the quality of the solution. Special additives - plasticizers - are responsible for its uniform application; at home they are replaced liquid soap or PVA glue. It is popular for interior decoration, for exterior finishing– . Also about the difference between plaster and putty.

Despite the rapid development construction industry and appearance the latest methods finishing of buildings and structures, none of alternative methods finishing is still not able to compete with traditional wall plastering. This is due to the undoubted advantages of the method and its features, as well as the ability of plaster to create a protective finishing layer on the surface of the walls being treated, which helps level the surface and create a decorative cover. With the help of plaster you can pour the foundation for a building, build a wall or make it finishing, as well as eliminate existing errors - to carry out all these activities you need a plaster solution. However, for each of these directions, different types of plaster mortar are required - in the process of finishing work, lime mortar will be required for plaster, for wall laying - masonry mortar. And that's not all existing varieties plaster solutions. Construction stores offer consumers to purchase ready mixture for preparing plaster, surprising consumers with the variety of these products. In order not to doubt the quality of the solution, you can prepare it yourself, saving a significant amount of money. To get to the heart of the matter and get acquainted with various types plaster solutions and methods for their preparation - read our article.

Preparing mortar for plaster: a step-by-step guide

What is plaster? Main Components

Plaster is rough facing material, with the help of which they level surfaces of various purposes - walls, ceilings, foundations. Depending on the style you choose for finishing the surface being treated, various components may be included in the plaster, however, regardless of the purpose of the plaster, the following components must be included in its composition:

A binder that increases the adhesive characteristics of plaster and its fastening properties;
A filler designed to relieve internal tension between particles of binding components, as well as to increase the volume of the solution;
Water intended for soaking and mixing components solution. Craftsmen who do not have sufficient experience in this area do not have a clear idea of what the difference is between certain types of mortar for plastering walls, if they consist of the same fundamental components. In addition, there is often an opinion among amateurs that you can start work by mixing cement with sand and water. However, experts assure that it is far from so simple and offer you the following recommendations.

Depending on the purpose of the plaster, it is customary to add the following components to its composition, each of which plays a specific role and gives the solution additional characteristics:

Lime is added in cases where it is necessary to give the solution additional viscosity. The lime used to prepare the solution can be slaked or quicklime, ground or multi-colored. It is a fragile material with long term drying out, resulting in lime mortars used for finishing work exclusively in dry rooms;

Gypsum or alabaster also does not have significant strength, but is characterized by a high hardening rate. This material It is advisable to use it for minor finishing activities and as an additional component to lime mortar, which will increase the speed of its drying;

Cement is a high-strength material that is resistant to atmospheric influences and retains its original characteristics after contact with water. Resistance to mechanical stress is another important advantage of cement. Plaster based cement-sand mortar used for external decoration of building walls, as well as surfaces located in areas of high humidity;

Clay is another component used as an additive to plaster mortar to increase its viscosity. Similar compositions are perfect choice for plastering and laying stoves, due to the fact that after firing, the solution, which contains clay, becomes as durable as possible;

Sand in the mortar for plaster is used as a filler, due to which the volume of the mixture increases. For solutions intended for various purposes, various types of sand are used, but the most effective is river sand, which is sorted and sifted before adding to the solution.

Main types of plaster solutions: proportions of ingredients

In accordance with the predominance of certain components, they distinguish the following types plaster solutions:

Lime mortar for plaster, to reduce the hardening time of which gypsum is sometimes used;
Cement mortar for plaster, the preparation of which often does not raise unnecessary questions;
Lime-cement mortar for plaster, which contains three components: lime paste, cement and sand;
Lime-gypsum mortar for plaster, combining optimal viscosity and hardening speed;
Clay mortar for plaster, to which some minor components can be added to give the mixture the necessary qualities.

Each of these plaster solutions has its own proportions, observing which you can create the optimal working mixture.

One of the most popular mixtures for finishing work is lime mortar, consisting of slaked lime, which is soaked in water, and sand. The ratio of the mass fractions of these components looks like 1: 2, less often 5;

Cement mortar for plaster consists of cement and sand, with a mass fraction ratio of 1: 3(4). To prepare the solution, the resulting dry mixture is poured with water;

To prepare a cement-lime mortar, you will need cement and sand, taken in a ratio of 1: 3(4), as well as a lime suspension, which is slaked lime diluted with water to the consistency of milk;

Lime-gypsum mortar for plaster is a regular lime mortar consisting of a mixture of sand and slaked lime, as well as gypsum. The ratio of the mixture of lime and sand to gypsum is 1:0.3;

Clay mortars for plaster are most often prepared with the addition of minor ingredients such as cement, sand, gypsum or lime. The choice of one or another component depends on the subsequent use of the solution. The approximate ratios of components in clay mortars for plaster are as follows:

Clay and sand in a ratio of 1:2 (5), which depends on the viscosity of the clay;
Clay, lime and sand in a ratio of 1: 0.3:4.

To prepare the solution, you will need to add water to the dry mixture, the volume of which depends on the required viscosity of the solution.

Important! Before preparing the solution, you need to make sure that it is necessary to use this particular mixture. For the greatest reliability, it is necessary to estimate physicochemical characteristics solution and place of their use. If the component composition is incorrectly selected, this may cause a decrease in the performance characteristics of the treated surface.

Thus, the choice of ingredients depends on:

Type of work (the solution for external plaster must be resistant to high humidity);
External conditions under which the building or premises are operated. These include: temperature, humidity, the presence of aggressive external factors;
The material from which the surface to be plastered is made.

Types of plaster depending on the proportion of ingredients:

Taking into account the proportions of the fundamental components, the plaster mortar can be divided into three types:

A fatty solution in which the binding component predominates. After drying, such a solution is prone to cracks;
Normal solution, characterized by an optimal ratio of filler and binder;
A thin solution, which is characterized by a small amount of filler, and therefore is short-lived and fragile.

To determine the type of mortar, all you need is a trowel and a little observation. Dip it into the solution and look:

If the solution sticks to the trowel in chunks, the solution is greasy;
If the trowel is only slightly dirty, the solution is thin;
If the solution lays on the trowel in the form of a thin crust, the ratio of binder and filler is normal.

Important! You can reduce the fat content of a solution by adding a filler to it, while you can increase the viscosity of a lean solution by adding a binder.

Composition of plaster mortar: general requirements

What should you pay attention to when choosing the composition of a mortar for plaster? First of all, it is important to follow the following points:

To plaster concrete and stone facades that are constantly exposed to moisture and precipitation, experts recommend using Portland cement and Portland slag cement to prepare a mortar for plaster;
If stone and concrete facades are not constantly exposed to moisture, it is recommended to use solutions based on the use of lime and cement, as well as other lime-based binders, for plastering them;
For finishing wooden and gypsum surfaces lime mortars are used, in which it is recommended to include alabaster to increase the rate of hardening of the mortar;
Solution for interior plaster premises with high humidity(the humidity level during operation is above 60%, which is typical for a kitchen, bathroom or bathhouse), the first layer is applied from cement or cement-lime mortar.

Decorative characteristics of plaster mortar: what to look for?

Experts often recommend paying attention to decorative solutions for plaster, which can be used both for interior decoration walls of the room, and for finishing facades. In production decorative solutions It is recommended to use the following substances as a binder:

Traditional, white and colored Portland cement for finishing facades and interior walls;
Gypsum and lime intended for colored plastering of indoor walls.
In the process of making decorative mortars, the use of marble, granite, dolomite, tuff and various fractions of limestone is widely practiced;

Important! To enhance the shine of the plaster composition, no more than 10% crushed glass and 1% mica are added to its composition. It is also practiced to add dyes - alkali-resistant and light-resistant pigments of natural origin, such as chromium oxide, ultramarine, ocher, red lead and other known substances.

How to make mortar for plaster: preparatory activities

First of all, it is necessary to prepare a container for mixing the solution, the volume of which depends on the required amount of solution. Experts recommend giving preference to a container whose configuration will ensure a complete sample of the solution. If the container has a complex configuration, the solution will harden in the bottom and corners of the container, which will subsequently lead to difficulties in subsequent attempts to mix the solution. Experts recommend choosing containers with a large tray bottom; therefore, it is not recommended to use a bucket as a container for mixing the solution.

In addition to the container, you need to prepare following materials and tools:

A dispenser, which can be used as any container of arbitrary volume;
An attachment for a drill (the so-called mixer), designed for mixing the components of the solution. If you do not have a drill attachment, you can mix the solution manually using a trowel or other available tool;
Binder (clay, lime or cement);
Filler (sawdust or sand);
Water.

Preparing mortar for plaster: a step-by-step guide

Before answering the question: “How to make a solution for plastering walls?”, it is necessary to answer that the preparation of the solution is carried out in several stages, the first of which involves preparing a dry working mixture, and the second – adding water to it and actually mixing the solution. There are two ways to prepare a solution for plaster: manual and mechanized.

Manual method of preparing plaster

It involves mixing the dry binder, during which the following rules must be observed:

First and important requirement– capacity requirement. Its bottom should be smooth and clean;
Sand is poured onto the bottom of the container in the form of a continuous layer or in the form of small piles;
The binder is distributed evenly over the sand layer;
The mixture is mixed and leveled with a rake;
The last two points must be repeated several times.

Important! If the mixture is not sufficiently mixed, its color will be characterized by heterogeneity and the presence of stripes, while the criterion for high-quality mixing of the composition will be its homogeneity.

Mechanized method of preparing plaster

To save time and effort, use a drill attachment or a so-called mixer to mix the solution. For mechanized method preparing a mortar for plaster, the consumption of which largely depends on its composition and quality characteristics, you will also need a bucket or any container that replaces it. The necessary components are poured into it the right proportions depending on the type of solution chosen and, using a mixer, mix it until smooth.

How to prepare cement-lime mortar for three-layer plaster?

The most common practice on construction sites is the use of cement-lime mortar. They are intended for installation of external and internal three-layer plasters. To properly prepare such a solution, you need to know the requirements for the composition and consistency of each of the three layers, as well as their other specific features.

Plastering walls and ceilings is an important stage of finishing work. Facing coating performs the functions of protection, decoration and additional insulation, perfectly hides seam joints and corrects minor masonry defects. Strength and durability depend on the correct ratio of the components of the solution.

The basic composition of any plaster always remains the same: binder, filler and water. The choice of binder depends on the nature of the finishing work (external/internal) and operating conditions (wet/dry microclimate). It can be cement, clay, lime, gypsum. Quarry or river sand is most often used as a filler. Sawdust, perlite, fine slag, and granulated polystyrene are less common. The filler ensures the strength and smoothness of the layer.

In practice, for finishing exterior and interior walls Cement mortars are most often chosen; they are characterized by increased strength and durability. Technological feature is a slow (about 12 hours) setting. To change the quality characteristics it is combined with other binders. The proportions of the main elements in the composition of the plaster determine its performance indicators.

Pour in pre-sifted dry sand. To clear it of pebbles and shells, you need to use a sieve with small cells. For primer plaster walls, a diameter of 2-3 mm is suitable, for finishing– no more than 1 mm.
Add cement and mix everything thoroughly. It is very important that the sand is well dried, then it combines evenly with the cement, does not burden it and prevents the formation of lumps.
Pour in water. First add no more than 2/3 of the total volume. Add the rest gradually, achieving homogeneity of the mass.

The prepared solution must be used within an hour. Left unspent, it begins to harden. If you add more water, you can restore elasticity, but the quality will be worse.

2. Cement-lime plaster.

Can be prepared in two ways:

Mix lime paste with sand and add cement to it. Stirring constantly, add water little by little to the desired consistency.
Cement and dry sand. Prepare lime milk by combining water with lime dough in a 1:1 ratio. Dilute the sand-cement mixture with milk.

3. Cement-clay.

Wet the lumps of clay with water and cover them with a thick rag.
Mix the swollen clay with sawdust in a ratio of 1:3.
Adding water little by little, bring to the required density.
To enhance the strength, add dry cement to the composition and mix thoroughly.

Solution consumption

The smaller building elements, the more seam joints in the masonry. This directly affects the unevenness of the walls. Deviations from the level can be both vertical and horizontal. Strong on leveling curved surfaces it will take a lot of composition. To calculate its consumption per 1 square meter, you need to multiply the thickness of the layer and the area of the walls.

To obtain curvature data, it is convenient to use a beacon. In this case minimum thickness plaster will be 6 mm. This slightly increases consumption, but all surfaces reach an ideal level.

To find out the maximum value of curvature, it is necessary to hang the walls in several places. The more measurements, the more accurate the calculations will be. For example, deviations of 10, 15 and 40 mm were found. These parameters need to be added up and the sum divided by the number of measurements: (10+15+40)/3=22 mm. The result is an average thickness of the plaster. Now all that remains is to multiply it by the area of the working surface.

For those developers who prefer to use ready-made mortar in dry form, it is easier to make calculations. On back side packaging manufacturers themselves indicate the exact consumption of material. With a layer thickness of 10 mm, approximately 10 kg of mixture per square wall is required.

Having decided to plaster the walls, you can purchase a ready-made dry mixture in the store, which easily turns into plaster after adding water. However, in this article we will take a different route and tell you how to prepare various plaster materials with your own hands.

Before you start preparing the solution, pay attention to its compliance with the base on which the plaster will subsequently be applied.

Cement and cement-lime mortars are used for external walls of buildings, facade works, as well as for rooms with high humidity levels.
Lime and lime-gypsum mortars are optimal for finishing wall and ceiling surfaces in rooms with normal level humidity.
Solutions in which clay is the main binder are an excellent choice for plastering wooden and stone surfaces in dry climates.

All materials must be sifted through a sieve with 3×3 (5×5) mm cells
To prepare the solution, use a box whose depth is 10-20 mm.
Any solution should be thoroughly mixed until a homogeneous mass is obtained using a wooden paddle 1 m long. The heterogeneity of the structure will prevent high-quality setting finishing material with base.
After mixing the solution, make sure its normal fat content by lightly poking it with an oar: good composition should stick slightly to the oar. If the solution sticks too much, add filler to reduce the fat content; if the solution does not stick at all, add a binder to the mixture.

Compound: 1 part cement and 2-3 parts sand

Theoretically, the proportions of the solution can be increased to 1:6, however, compositions in which more than 3 parts of sand per 1 part of cement are characterized by low plasticity, and therefore are very labor-intensive to work with.

Pour a bed of sand into the box for diluting the mixture.
Cover the sand with several layers of cement.
Mix dry ingredients thoroughly.
Gradually add water, stirring constantly.
Finish adding water until you have a creamy mixture.
If desired, you can add a little PVA glue or building plaster to the solution - this will speed up the setting of the plaster. In order to slow down the setting, add a small amount of detergent to the drawer.

Please note that the solution must be used within an hour after preparation, so for large volumes of work it would be logical to mix the components in stages, in small portions. Long-term storage of the composition will lead to its loss of good strength characteristics.

Cement-lime mortar

Compound: 1 part cement, 3-5 parts sand, 0.7-1 part lime mortar

Take quicklime and place it in a non-plastic bucket.
Add to the bucket warm water(the liquid should completely cover the lime layer).
Quickly cover the bucket with a lid and press down with a heavy load - when boiling, lime tends to “overflow its banks.”
Wait until the end chemical reaction and carefully strain the resulting cloudy substance through cheesecloth.
Every other day you can use lime mortar to create plaster.
Next, prepare a dry mixture of sand and cement (proportions 1:3).
Pour the milk of lime into the box with the dry mixture and stir until smooth.

Mortar

Compound: 1 part lime mortar and 3 parts sand

“Quench” the lime with water to obtain a lime mortar.
Add a little water and sand to the box with lime, which will make it easier to grind the composition.
Stir the mixture, carefully removing any lumps.
Add the remaining sand in small portions while adding water.
The readiness of the composition will be confirmed appearance solution: normal fat content and medium thickness.

Lime mortars can only be used on the day of production.

Lime-gypsum mortar

Compound: 1 part dry plaster (alabaster) and 3 parts lime paste

Dilute the plaster with water until you obtain a dough-like mass.
Add lime mortar to the plaster and mix.

Use the solution immediately after preparation, as it sets record-breakingly quickly - within 3-4 minutes, and complete hardening occurs within half an hour.

Clay solutions

Prepare clay mortar you can use a technology similar to creating limestone. However, keep in mind that ready-made clay mortar is fragile, and therefore most often it is used with the addition of gypsum, lime or cement.

Clay gypsum solution

Compound: 1 part clay dough (clay mixed with water until liquid), 0.25 parts gypsum and 3-5 parts sand.

Clay cement mortar

Compound: 1 part clay dough, 0.2 parts cement, 3-5 parts sand.

Clay-lime mortar

Compound: 1 part clay dough, 0.3-0.5 parts lime dough and 3-6 parts sand.

To obtain all the solutions, it is necessary to mix the binder components with each other, and then gradually add sand.

Please note that making solutions containing different chemical additives(for example, sodium nitrite or chlorinated water) can only be used by specialists.

Preparation of plaster mortar (video):

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.

It probably doesn’t seem new and everyone has long known that modern plaster mortars using new technologies are made 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 a solution for plastering work, 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 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.

Cement brand	The ratio of cement: lime: sand and the grade of mortar produced
Cement brand

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 manufacture 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.

Material	Plaster thickness, cm
Material
Lime mortar, l

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 rocks are used semi-precious stones. In addition, they may contain impurities; the grains themselves can be various 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 at the construction site, where the preparation work takes place plaster mixture. 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 of a binder material, forms a solid artificial stone with similar properties.

For 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. In this case, 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.

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 are 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, by chemical exposure 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 influence on the binder 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’s difficult to explain the principle of operation, but everyone knows that salty 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 metal, glass or pulp 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.