Preparation and application of lime-cement mortar

Specifications

The composition of such a solution necessarily includes cement, sand, slaked lime and water.

It is worth paying attention to the fact that it is necessary to add slaked lime. Otherwise, the quenching reaction will begin in the solution itself when water is added, and bubbles, forming already inside the solution, will lead to cracking of the plastered surface.

This process of bubble formation will lead to a deterioration in the quality of the solution and to brittleness after it dries.

Building mixtures, their composition and properties are regulated by various GOSTs. This is necessary for the standardization and regulation of building codes. GOST 28013-98 is the main regulatory legal act governing the technical requirements for mortars and materials included in the composition.

This standard also includes the characteristics of quality indicators, acceptance rules and conditions for the transportation of ready-made solutions. It contains the qualitative and quantitative characteristics of masonry mortars, materials for plastering and for interior work, used in various operating conditions.

Cement mortars

Cement is prepared from a mixture of ordinary cement and medium-fraction sand. The proportions can be different, they depend on the brand of cement used and can be: one part of the cement is taken from three to six - sand.

Stir the dry mixture with the addition of water until a homogeneous mass is formed.

First, the dry mixture is kneaded, after that water is gradually added, then everything is mixed until a homogeneous, thick mass is obtained. But this option is not the best, since ordinary cement is inactive, even when using any brands, it turns out to be too tough, too strong.

Cement-lime mortar for brickwork consists of lime and cement. The cooking process is as follows:

1. Slaked lime, that is, lime dough, is diluted to the state of thick milk, after which it is filtered through a sieve.
2. On the basis of sand and cement, a dry mixture is prepared, which is dissolved with milk of lime, and then thoroughly mixed. The addition of lime can increase the plasticity of the resulting batch; such a mixture is recommended to be used for laying bricks of any type.

Simple mortar for masonry

The simplest solution is prepared from a binder (it can be ordinary cement or lime) and sand. In some cases, clay can also act as a binder, but this is a very highly specialized work that is not done so often.

The most common cement-sand mortar has the following proportions: one part of cement to three - sand of the middle fraction. The resulting mixture is thoroughly mixed first in dry form, after which plain water is gradually added to it. Stirring is carried out until the resulting composition acquires the proper density and mobility.

It is not so difficult to check such characteristics: the container in which the solution is stirred must be tilted at an angle of forty degrees; if the mixture does not pour out, then you can start the masonry process.

Complex styling solution

The solution should not spread and slide well from the surface.

Complex mixing for bricks is a mixture of several components and a binder that affects the physical characteristics. Among such complex mortars for brickwork, cement-lime-clay, cement-lime and others are used, thanks to which the masonry is simpler, but also reliable.

Clay, for example, is added to make the composition more plastic. It does not fall apart during operation, it fits very neatly and easily. The use of plasticizers makes the brick mix indispensable when laying facade walls.Such a mixture is very economical, it provides uniform compaction, when spreading it is conveniently leveled over the surface of the previous row. Therefore, many experts recommend spending a little more time preparing the solution, but then this will only help in the work.

Mixing proportions

There is a classic version of the mixture, which is determined by the ratio of 1: 3 - 1 part of cement and 3 parts of sand. Both components are first mixed dry with each other, and then water is added in portions to this mixture. All this is thoroughly mixed until a solution is formed, similar in consistency to thick sour cream. Be sure to give the finished mixture 15 minutes to thicken, and then mix again.

By the way, the cement-sand mortar “lives” no more than 1.5 hours. After which it begins to lose moisture and dries out. So a small batch is a justified decision.

For mixing the components, it is recommended to use a construction mixer or a drill with a special attachment. If you require a large amount of material, for example, for pouring a foundation, we recommend that the cooking process be carried out in a concrete mixer.

Note that the end result is a lump-free formulation as a homogeneous mass.

Masonry sand

The main ingredients of the solution:

Cement is an astringent component. It must be in paper bags. It is recommended to buy it before starting construction processes. That is, it must be "fresh". Indeed, during long-term storage, this material cakes, which means it loses its qualities.
Sand is a filler. There is one quality issue here. There should be no foreign materials in the sand. This is especially true for clay. Therefore, it is recommended to purchase river sand

Pay attention to the fraction of the material. For example, the fine one promotes the spreading of the solution, therefore it is not used for the masonry mixture. But in screed solutions such sand is an ideal choice.

The coarse fraction is not used for the preparation of plaster, although it works great in foundation solutions.
Water is the basis, so it must be clean. The main requirement for it is the absence of acidic and oily impurities.

Features of choosing a brand of solution

Now you can move on to the proportions and deal with such an indicator as the brand of the solution:

• The masonry composition has the M100 brand. It is used in the construction of walls and protective structures made of bricks or blocks based on different materials. This will require M400 cement and sand, which are mixed in a 1: 4 ratio.
• To increase the strength of the masonry, you can take a solution of the M200 brand. To do this, you will have to reduce the amount of sand by 2 times.
• To level the floor bases, the M300 solution grade is used. To do this, you can use cement M400 or M500 with the addition of water and sand in a ratio of 1: 3: 0.5.
• For plastering the walls, use exactly the same mortar as above, only with a slight increase in the amount of cement. For example, it could be 1.2-1.5. Plaster solutions are often made with the addition of milk of lime. This reduces the strength of the material, but increases its plasticity. In this case, the ratio of cement-sand-milk will be 1: 5: 2.

Standard proportions

We make a solution in the right ratio

There are certain technological standards that regulate the ratio of the components of the building mixture. Here are three examples:

1. To prepare a solution for screed, use a ratio of 1: 2-1: 6. In this case, the amount of water is not indicated, but only the cement-sand ratio is indicated.
2. In low-rise construction, 1: 3 or 1: 4 solutions are most often used.
3. For structures under construction - from 1: 3 to 1: 6.

Why is water not specified in the standards? The fact is that it is easy to make a mistake with the volume of water. After all, the sand can be wet, and the degree of moisture cannot be determined at home. At the plant, however, this indicator is strictly controlled.What can you offer to those using handcrafted solutions? To do this, it is better to double the batch if the first one turned out to be liquid. Just add cement and sand to it according to the standard, but reduce the amount of water.

Today, facing tiles and stone are placed on ready-made adhesive mixtures, which greatly simplifies the process of preparing the composition. But since we are considering all cement-sand mortars, this masonry material should not be ignored. Let's just designate the proportions - 1: 2.4: 0.4. Here is such a non-standard ratio.

Many people ask a question regarding the determination of the volume of one portion. What means and tools can be used to measure the required amount of material? In hardware stores, special measuring buckets are sold, with the help of which the measurement or plumb line of the construction mixture is carried out.

Requirements for masonry mixture

In detail, the requirements for masonry mortars are described in GOST 28013-98. According to this document, the following requirements are imposed on mortar mixtures:

• the composition must have a high degree of adhesion to bricks and other substrates;
• withstand a large amount of freezing and defrosting;
• in order for the masonry not to collapse under the influence of atmospheric influences and temperature changes, masonry mixtures must have high indicators of water resistance;
• due to the plasticity of the mortar, during the masonry process, it becomes possible to timely adjust the position of the masonry material, which significantly increases the quality and productivity of work;
• water-retaining properties prevent the mixture from decomposition and precipitation of heavy fractions;
• the strength characteristics of the composition are decisive in the calculation of building structures. This parameter shows what maximum loads the material can withstand. The grade of the solution reflects its strength in kgf / cm2.

Failure to comply with these requirements leads to the formation of cracks in the brickwork, increased consumption of the mortar mixture, an increase in the thickness of the joints and reduces the productivity of work.

Making sawdust concrete with your own hands

Independent production of lightweight concrete composite is carried out according to the following algorithm:

1. The necessary materials are being prepared. The components do not need to be purchased in advance. All components can be prepared immediately before production by visiting stores or warehouses of building materials, as well as using waste products from woodworking enterprises.
2. The ingredients are mixed according to the proportion. Mixing of components can be carried out mechanically using a concrete mixer or manually using shovels. Automation of the technological process by using a concrete mixer increases productivity, improves mixing intensity, and has a positive effect on product quality.
3. Molding is in progress. The group molding process is mainly used, when the premixed composition is poured into several dozen forms. Single and group forms of a collapsible structure are used, made of wood 2 cm thick and upholstered with metal or plastic. The use of plastic wrap makes it easier to remove the finished product.
4. Drying of finished products is carried out in a natural way. The molds are removed 4–5 days after pouring by loosening the wing nuts, removing the threaded rods and disassembling the molding box. The natural drying process lasts, depending on the wood species, up to three months, during which the moisture concentration is significantly reduced, and the product acquires operational strength.

Standard composition of concrete with sawdust: cement-sand mixture, wood shavings, lime (if necessary)

Why do we need plasticizers

A plasticizer is a special composition added to a solution to increase its plasticity and elasticity.

The beneficial effect of using a plasticizer:

• Reducing the amount of water that worsens the solidification of the solution.
• Increasing the moisture resistance of the seam.
• Increased frost resistance.

Plasticizers have different purposes:

• Catalysts. Serve for acceleration and greater solidification of the solution.
• Modifiers. They allow you to get additional possibilities of the seams - greater resistance to mechanical stress, moisture resistance, etc.

In addition, plasticizers make it possible to obtain a more elastic joint, which compensates for the thermal expansion of the lining. This ability helps to maintain the strength of the bonds with the load-bearing wall and prevents the formation of cracks in the joints that can accumulate moisture.

Do-it-yourself solution preparation

First you need to extinguish the lime for plaster so that it is suitable for work. This requires a metal container, since the reaction is accompanied by a large release of heat and an increase in volume by a factor of 3. Lime packaging indicates the slaking speed: slow (25 minutes or less), fast (8 to 10 minutes), medium, 15 to 20 minutes. It is better to stir the mixture with a shovel or paddle. Slaking is carried out for at least a day, however, ideally, use lime that has stood for a month.

The note! Sand before preparing the plaster also needs to be prepared: remove impurities, clean it by passing it through a sieve.

Instructions for creating a limestone-sand mortar:

1. The sand is mixed with lime dough in the selected proportion. This is done dry and mixed thoroughly.
2. After that, water is gradually added to the container. It is not necessary to immediately pour in the entire volume, it is poured in a thin stream, and the solution is constantly mixed.

This completes the preparation, you can start plastering the surface.

What is lime plaster

Adding lime to solutions can significantly increase the plasticity and crack resistance of the plaster. It becomes much easier to work with it, it does not dry out so quickly, it easily sticks even to wood, and the surface is smoother, without defects. It also provides excellent protection against mold and mildew. Another indisputable advantage is its environmental friendliness - unlike synthetic additives, lime is absolutely harmless.

Lime is widely used in construction as a plasticizer. However, when plastering facades, it should be borne in mind that it is allowed to be used only in areas with a dry climate. Such solutions are not recommended for use in rooms with high (over 60%) humidity.

Lime plaster is considered warmer and more vapor-permeable, that is, "breathable", and it is much easier to remove it from the walls in case of repair than, for example, ordinary cement. But excess lime can weaken the surface's strength. That is why it should be added in moderation, precisely adhering to the proportions.

As you can see, lime plaster has many advantages. The disadvantages include not as high strength as that of cement compositions. Also, it is not recommended to use it in damp rooms and

But special strength is not required from such a solution. After all, the purpose of plastering is to level the surface and cover up small cracks. A stronger mortar is required when laying. However, in this case, according to SNiP, it is allowed to add a small amount of lime dough or clay to it to increase plasticity.

When slaking lime, you should be extremely careful - splashing hot mixture can cause burns. The smallest lime dust, which can settle on the mucous membrane, also has a harmful effect. Therefore, when working, use protective clothing, gloves and a respirator.

Preparation of masonry mortars

Since various types of mixtures can be used for the masonry composition, we will consider in more detail how to prepare a mortar for laying bricks.

Cement slurry proportions

Sand-cement compositions are widespread in capital construction and other areas where increased requirements are imposed on the strength characteristics of brickwork.

Before preparing a masonry mortar, it should be remembered that an excess of cement in the working mixture does not increase its strength, and in some cases even worsens its characteristics. Only strict adherence to the dosage will ensure the optimal performance of the masonry mixture. The proportions of the most common cement-based compositions are given in SP 82-101-98, which clearly regulates the percentage of ingredients in various types of cement masonry mixtures.

The table shows the percentage of ingredients in the masonry mortar, depending on the grade of cement used.

Scope of application of cement mortar, depending on the strength characteristics

Below is the scope of application of various grades of masonry mortars.

• M25. Used for plastering and floor screed. The composition does not contain any additional ingredients.
• M 50. It is used for brick and masonry in the construction of low-rise buildings and structures. May contain plasticizers, colorants and other additives.
• M 75. It is used for laying concrete slabs, installing reinforced concrete structures, erecting internal partitions and installing a concrete floor screed.
• M 100. It is widely used in monolithic construction, masonry work and pouring lightly loaded strip foundations.
• M 150. It is mainly used for foundation work on loose soils.

Proportions of cement-lime mortar

The percentage of cement, lime and sand in the cement-lime mortar is shown in the table.

The solution is prepared in the following sequence:

1. Lime-fluff is diluted to the consistency of kefir, after which it is filtered.
2. A dry sand-cement mixture is prepared separately.
3. The strained lime is added to the cement-sand mixture and thoroughly mixed until a homogeneous mass is obtained.

Proportions of cement-clay mortar

The ratio of cement, clay and sand in the cement-clay masonry mixture is shown in the table.

The addition of clay increases the moisture retention capacity of the masonry mix.

The low strength of the lime mortar prevents its widespread use in masonry work. Most often, lime mixtures are used for plastering work. The proportions of the working solution depend primarily on the fat content of the lime and can range from 1/2 to 1/5.

Concrete solution and its composition.

Cement should only be stored in a closed, dry room! Per 1 bag of cement, the dosage of the concrete solution is as follows:

Such a solution is used for various construction work (screed, foundation, floors, beams). Steel reinforcement is placed in concrete to increase strength, resulting in reinforced concrete. Bonding the reinforcement to the grout facilitates oxidation of the metal surface.

The calculation of the required volume of concrete is calculated using the formula:

Concrete volume = Length x Width x Height, for example: 10 x 5 x 0.1 m = 5 m3

When adding water to a solution or building mixture, the following proportions must be observed:

Volume of water = Weight of cement / 2, for example: 25 liters of water per 50 kg bag of cement.

Preparation of simple plastering compounds

Cement mortar is the simplest and most common

Simple plasters include those solutions based on one binder. These include the following plaster solutions:

1. Cement.
2. Lime.
3. Clay.
4. Plaster.

Cement

This composition is the most common type of finish: its consistency is very similar to laying mortar for bricks. However, the density in this case is different, moreover, the use of various additives and plasticizers is widely practiced.

Although this may sound unexpected, the quality of the sand used is most important for personal control. That is why, before use, it is carefully sieved through a special sieve to remove all impurities and debris.

After cleaning the sand, the mixing procedure begins: the main components must first be mixed dry. The proportions of cement mortar for plastering walls outside the room is taken in a ratio of 1: 5 sand to M500 grade cement. As for the interior decoration, in this case, cement is mixed with sand 1: 4, where M400 cement is taken for preparation. After acquiring the required homogeneity with dry components, add water to the composition and stir until mushy. To carry out such a procedure, both a trough and a construction mixer can be used.

Lime

Lime acts as a binder in lime mortar

This composition differs from the previous one in the absence of cement: lime is used as a binder in this case: it should only be slaked and have excellent qualities. The first step is to grind it thoroughly so that the particles are as small as possible. Then water and sand are added to a bowl with lime powder, with constant stirring of the entire material

It is very important that the resulting lime plaster mortar does not contain lumps, with a mixture similar to that of dough. Then another portion of refined sand is added to the resulting mass, in a ratio of 3: 1

After that, the final stirring of the plaster is carried out with the addition of water: the finished consistency of the solution should resemble thick sour cream.

Clay

This easy-to-prepare plaster mortar is the oldest known. In the course of the development of construction technologies, its composition has undergone some changes, because clay in its pure form is quickly washed off by rains. To strengthen the finish, the addition of cement, lime and gypsum is practiced, which contributes to an increase in its durability and reliability: while the availability of preparation is preserved. In the process of preparing clay plaster, the main component must be thoroughly cleaned of all kinds of debris and impurities. Then, clean and dry clay is soaked in water for 3-5 hours until it is completely soaked: the preparation of the solution is completed by adding sand to its composition, at the rate of 2-4 parts of sand to one part of the clay mixture. Clay plaster is usually used for interior decoration.

Gypsum plaster

Most often, with the help of gypsum plasters, final operations are carried out to level the walls, with the possibility of applying not only to concrete and brick, but also to wooden bases. The first recipe for preparing such a solution involves the use of 3 kg of chalk and 1 kg of gypsum, while the chalk is crushed to a state of dust, followed by mixing with gypsum. In this case, water is not used, since a 5% wood-type glue is used as a solvent. The proportions of the adhesive in this case vary, depending on the required thickness of the final solution. This type of solvent not only makes the mass of the plaster homogeneous, but also makes it possible to somewhat slow down the hardening process. However, the drying speed of gypsum plaster is still quite high.

Working with gypsum plaster requires skill, as the mixture dries quickly

The second method of preparing a finishing solution from plaster is especially suitable in cases where it is required to plaster painted bases or chipboard partitions. In this case, you will need to take 2 kg of gypsum, 1 kg of drying oil and 100 g of desiccant: after thorough mixing, the composition should be immediately worked out. The reason for this is the lightning-fast drying of the desiccant: when working in this case, you will need the appropriate construction skill.

Proportions of mortar for masonry

For brickwork, as well as for plaster, cement-lime or cement mortars are created. However, it must be borne in mind that in this case the grade of the mortar should not be higher than the strength class of the bricks used for masonry. It is most convenient to work with a plastic solution: it is easy to apply, but does not drain from the masonry elements. In order to prepare a mixture that is optimal in consistency, you need to know the most successful ratio of all components of the solution.

Preparation of branded cement mortars

The brand of the solution depends on the ratio of cement and sand in the solution. The more sand and less cement, the less durable the solution is obtained and, accordingly, the lower its grade.

• 1 part of cement: 5 parts of sand - the proportion of the preparation of the MZ grade solution;
• 1 part of cement: 4 parts of sand - the proportion of the preparation of the M5 grade solution;
• 1 part of cement: 3 parts of sand - the proportion of the preparation of the M8 grade solution.

Recipe for plastic mortar M3 for brickwork

To create 1000 liters of M3 grade solution, you need:

• water - 340 l.;
• sand - 2064 kg.;
• cement - 268 kg.

To create 200 liters of M3 grade solution, you need:

• water - 54 l.;
• sand - 206 liters. (330 kg.);
• cement - 33 l. (43 kg.).

To create a M3 grade solution from a 25-kg bag of cement, you need:

• water - 32 l.;
• sand - 120 l.(192 kg.);
• cement - 25 kg.

Recipe for plastic cement mortar M5 for brickwork

To create 1000 liters of M5 grade solution, you need:

• water - 350 l.;
• sand - 2000 kg.;
• cement - 327 kg.

To create 200 liters of M5 grade solution, you need:

• water - 56 l.;
• sand - 320 kg.;
• cement - 52 kg.

To create a M5 grade solution from a 25-kg bag of cement, you need:

• water - 27 l.;
• sand - 177 kg.;
• cement - 25 kg.

Recipe for plastic cement mortar M8 for brickwork

To create 1000 liters of M8 grade solution, you need:

• water - 360 l.;
• sand - 1904 kg.;
• cement - 412 kg.

To create 200 liters of M8 grade solution, you need:

• water - 58 l.;
• sand - 305 kg.;
• cement - 66 kg.

To create a M8 grade solution from a 25-kg bag of cement, you need:

• water - 22 l.;
• sand - 115 kg.;
• cement - 25 kg.

Recipe for plastic cement-lime mortar M3 for brickwork

To create 1000 liters of cement-lime mortar, grade M3, you need:

• water - 470 l.;
• sand - 1760 kg.;
• cement - 191 kg.;
• hydrated lime - 106 kg.

To create 200 liters of cement-lime mortar, grade M3, you need:

• water - 75 l.;
• sand - 282 kg.;
• cement - 30.5 kg.;
• hydrated lime - 17 kg.

To create a plastic cement-lime mortar of the M3 grade from a 25-kg bag of cement, you need:

• water - 61 l.;
• sand - 230 kg.;
• cement - 25 kg.;
• hydrated lime - 14 kg ..

Recipe for plastic cement-lime mortar M5 for brickwork

To create 1000 liters of cement-lime mortar, grade M5, you need:

• water - 420 l.;
• sand - 1840 kg.;
• cement - 266 kg.;
• hydrated lime - 74 kg.

To create 200 liters of cement-lime mortar, grade M5, you need:

• water - 67 l.;
• sand - 294 kg.;
• cement - 42.5 kg.;
• hydrated lime - 12 kg.

To create a plastic cement-lime mortar of grade M5 from a 25-kg bag of cement, you need:

• water - 55 l.;
• sand - 173 kg.;
• cement - 25 kg.;
• hydrated lime - 7 kg.

Features of the creation and use of mortars for brickwork

The general technology for creating mortars for brickwork is slightly different from the preparation of plaster mortars: first, water is poured into a concrete mixer (about 2/3 of the required amount), then a dry mixture of cement, sand and lime is added (if needed). After that, you can top up the remaining water. The mixture should "spin" in the concrete mixer for at least 2 minutes.

Cement and cement-lime mortars for brickwork must be fully used within two hours from the moment of creation. At temperatures above +25 degrees, the solution may become unusable for one hour.

It is recommended to moisten the bricks before applying the mortar to the masonry. In this case, the masonry elements will not absorb water from the solution.

When applying the mortar with a trowel, you do not need to press it into the holes of the brick, as this reduces the thermal insulation properties of the walls.

Using different proportions to create masonry mortars, it must be borne in mind that the amount of loose components of the mixture is always indicated in a specific sequence: first cement, then lime and sand. That is, a ratio of 1: 1: 4 means that one part of cement is taken, one part of hydrated lime and four parts of sand.