In the construction industry, two types of mortar predominate - plaster and masonry. Their compositions differ quite a lot, but the presence of thick material remains unchanged, which contributes to workability. Mostly masonry mortars for walls consist of lime and cement. The composition, in turn, must be sufficiently pure and not contain any impurities that could affect the quality of the material. Masonry mortar for bricks is not picky and coarse sand is used in its production, while plaster mortar does not accept coarse sand. abrasive materials and contains only pure river sand.
Any mortar for bricks, for example, grades M25, M50 and M75 based on cement and limestone, comes in three types, according to the conditions of its use:
- a solution used for plastering walls. Classified into grades M10, M25, M50 according to GOST 28013-98;
- mortar for laying bricks. This category includes grades M50, M75, M100 according to GOST 28013-98;
- cement-lime mixture made specifically for screed. There are two types M150, M200 according to GOST 28013-98.
Mixing technology
The procedure for mixing the solution should be carried out in some spacious container. At the first stage, fill the container with water, and then gradually begin to add lime. After stirring, you should get milk of lime, to which sand is then added. The required masonry or plaster mortar for walls and bricks can also be prepared in another way - by adding water to the already mixed powder composition.
In mortars for plastering walls, an important component is fine-grained sand. The raw materials must be highest quality, and the components are completely free of unnecessary impurities. Acceptable rate foreign substances cannot exceed 5%. The use of raw materials that contain clay significantly reduces the consumption of binder components, however, after such a coating dries, the material becomes covered with cracks.
When mixing plaster material for walls, you should carefully control the proportion of fine-grained sand, because an excess of silicate contributes to the fact that the consumption of the binder will be excessive and the material will be thicker than necessary, which will also inevitably lead to the formation of cracks after drying.
Based on slaked lime, it is used in finishing rooms where there is high humidity air. Among other things, there is also hydraulic plaster, which hardens faster than a composition based on slaked lime. The advantages of this solution include high degree hydration, which is an excellent factor for using hydraulic plaster in winter.
If you set out to prepare a mixture for plastering walls on cement based with the addition of lime, you should make sure in advance that there are three main components of the material:
- astringent substance, in in this case cement and lime;
- in addition to the main substance, the cement-lime composition should also include a filler, mainly sand (the sand should be either fine-grained or quarry sand);
- water.
To prepare lime mortar, you will need cement grade M75, M50 or M25 according to GOST 28013-98. The possible downgrade of the cement grade depends on the storage conditions and the time that has passed since the package was opened. This is explained by the fact that the oxidation process, after a certain period, negatively affects the composition of the substance. When adding sand, careful attention should be paid to the purity of the silicate.
To achieve more even mixing, you should use a sieve. This important step, because Excessive filling of raw materials with undesirable elements can significantly reduce the quality of the prepared solution.
In order to increase plasticity, you can add PVA glue in a ratio of approximately half a liter of glue per 20 liters of solution. Also in some cases it is possible to add liquid soap- this is what concerns budget options, with a more responsible approach to cooking masonry mortar for brick it is still better to add special plasticizers.
Since the solution is prepared using cement and lime, it should Special attention pay attention to the quality of the second component. It may happen that the purchased lime turns out to be quicklime, so it is worth carrying out the slaking procedure in accordance with the requirements safe operation. This process involves loading raw materials into a container and filling it with water. During this procedure, very violent chemical reactions oxidation, which may result in the formation large quantities
heat. To protect yourself, the procedure should be carried out wearing a mask and special glasses; you can use rubber gloves to protect your skin.
Types of solutions
Let's consider the main brands of cement mortars.
, including heavy rainfall.
Brand M75 If you are in doubt about which mortar is best to choose for laying bricks, it is recommended to pay attention to cement mixtures M75, M50 and M25. Combined with high strength, this material has excellent waterproof qualities. It is very difficult to cook at home this type
lime mortar. This is explained by the fact that its production uses very thorough mixing, which can only be achieved using special equipment. The condition of cement can also be affected by weather . It is highly not recommended to lower the temperature during the period when hardening occurs. In turn, high temperature regime
can cause all the moisture in the solution to evaporate too quickly, thereby making the concrete brittle.
- The main technical characteristics of this brand include:
- amazing moisture resistance;
- resistance to extremely low temperatures;
, including heavy rainfall.
Mortar grade m 100 is widely used in the construction of both civil buildings and in the construction of industrial facilities. Another feature of the m 100 solution is that there is no crushed stone in this cement-lime composition. Only special sand for construction needs that meets all quality standards in accordance with GOST can act as a filler.
Basic Rules
The source material must be best quality, since neglecting this factor can negatively affect the quality of the work done. When plastering walls, both brick and wood, only high-quality raw materials should be used. Before mixing the starting materials, you need to make sure that they have sufficient flowability. Crumpled mixture and foreign solids may indicate that the raw material has been exposed to moisture. This factor completely negates all the adhesive properties of the solution and, after hardening, makes it extremely fragile.
An important factor is that the use of masonry mortar for bricks, which contains lime, can only be used when plastering walls and other concrete surfaces. For processing various kinds cornices and other interior/exterior elements, it is necessary to choose cement that boasts good durability, such as cement grades M400, M75, M50 and M25 according to GOST 28013-98.
In order for the plaster coating for walls or screed to last for a long time, you need to comply with everything necessary requirements during the procedure of mixing dry ingredients. For finishing types of mortar, it is worth using fine river sand as a filler, which must first be sifted through a sieve.
You also need to ensure that the mixture is not too “greasy”; this factor can significantly spoil the quality of the final coating because After the material has dried, cracks may form. For improvement physical properties concrete, at the stage of mixing the components, it is recommended to add various plasticizers, as well as PVA glue or liquid soap.
It is also worth taking into account that some types of masonry mortar for bricks, for example, M25, M75 and M100 according to GOST 28013-98, cannot be produced using a homemade method, due to complex technology preparations using high-tech equipment, thanks to which an amazing degree of mixing of components is achieved.
Construction mortars are characterized by three main parameters: density, type of binder and its purpose. Depending on the density (in a dry state), heavy (density 1500 kg/m3 or more) and light (density less than 1500 kg/m3) solutions are distinguished. For the manufacture of heavy solutions heavy quartz or other sands are used; fillers in light solutions are light porous sands made from pumice, tuff, slag, expanded clay, etc. Light solutions are also obtained using foaming additives - porous solutions.
Based on the type of binder, construction mortars are divided into cement (based on Portland cement or its varieties), lime (based on air or hydraulic lime), gypsum (based on gypsum binders) and mixed (based on cement-lime, cement-clay, lime-gypsum binders) . Solutions prepared with one binder are called simple, and solutions prepared with several binders are called mixed (complex).
According to their intended purpose, mortars can be masonry (for masonry, installation of walls from large-sized elements), finishing (for plastering premises, applying decorative layers on wall blocks and panels), special ones with special properties (waterproofing, acoustic, X-ray protective).
The choice of binder depends on the purpose of the solution, the requirements for it, the temperature and humidity conditions of hardening and the operating conditions of the building. Portland cements, pozzolanic Portland cements, slag Portland cements, special low-grade cements, lime, and gypsum binders are used as binders. To save hydraulic binders and improve technological properties mortars Mixed binders are widely used. Lime in mortars is used in the form of lime paste or milk. Gypsum is used mainly in plaster mortars as an additive to lime.
The water used for solutions should not contain impurities that have a harmful effect on the hardening of the binder. Suitable for these purposes tap water. If the solution is used in winter conditions, hardening accelerators are added to its composition, as well as additives that reduce the freezing point of water (calcium chloride, sodium chloride, potash, sodium nitrate, etc.)
Composition of mortar denoted by the amount (by mass or volume) of materials per 1 m 3 of solution or by the relative ratio (by mass or volume) of the original dry materials. In this case, the binder consumption is taken as 1. For simple solutions, consisting of a binder (cement or lime) and not containing mineral additives, the composition is designated 1:4, i.e. per 1 wt. parts of cement account for 4 wt. hours of sand. Mixed mortars consisting of two binders or containing mineral additives are designated by three numbers, for example 1: 3: 4 (cement: lime: sand).
Quality mortar mixtures characterized by their workability - the ability to be laid without special compaction on the base in a thin layer, filling all its unevenness. Workability is determined by the mobility and water-holding capacity of mortar mixtures.
Mobility- the ability of the mortar mixture to spread under the influence of its own mass. Mobility is determined (in cm) by the depth of immersion in the mortar mixture of a standard cone weighing 300 g with an apex angle of 30° and a height of 15 cm. The deeper the cone is immersed in the mortar mixture, the greater mobility it has. The degree of mobility of the mixture depends on the amount of water, the composition and properties of the starting materials. To increase the mobility of mortar mixtures, plasticizing additives and surfactants are added to them. The mobility of mortars, depending on their purpose and method of installation, should be as follows.
Brick wall laying, concrete stones, stones from the lungs rocks: 9-13.
Masonry walls from hollow brick, ceramic stones: 7-8.
Filling horizontal joints when installing walls made of concrete blocks and panels; Joining vertical and horizontal seams: 5-7.
Rubble masonry: 4-6.
Filling voids in rubble masonry: 13-15.
Water holding capacity is the property of a solution to retain water when laid on a porous base. If the mortar has good water-holding capacity, partial suction of water compacts it into the masonry, which increases the strength of the mortar. Water holding capacity depends on the ratio components mortar mixture. It increases with increasing cement consumption, replacing part of the cement with lime, introducing highly dispersed additives (ash, clay, etc.), as well as some surfactants.
Strength hardened mortar depends on the activity of the binder, water-cement ratio, duration and hardening conditions (temperature and humidity environment). When laying mortar mixtures on a porous base that can intensively suck out water, the hardening strength of the solutions is much higher than the same solutions laid on a dense base. The strength of the mortar depends on its brand, which is determined by the compressive strength after 28 days of hardening at an air temperature of 5-25°C. The following brands of solutions are available: 4, 10, 15, 50, 75, 100, 150, 200 and 300.
Frost resistance solutions are determined by the number of cycles of alternating freezing and thawing until the loss of 15% of the original strength (or 5% of the mass). Based on frost resistance, solutions are divided into Mrz grades from 10 to 300.
Choice of brand and solution composition depends on the type of building, its operating conditions, as well as on the planned degree of durability (Table 4). Buildings located above ground relative humidity air inside up to 60%, as well as underground structures in soils with small level humidity, placed on cement-lime and cement-clay mortars. In this case, the solutions should have a ratio of the volume of lime (clay) paste to the volume of cement not exceeding 1.5:1. If the humidity inside the building is more than 60%, or the soil has high humidity, this ratio should not exceed 1:1. Lime and clay are not used in mortars for masonry located below the level groundwater.
Table 4. Brands of masonry mortars.
| Type of solution | Durability of buildings | ||
| I | II | III | |
| Structures located below the level of the waterproofing layer | |||
| Cement-lime when filling the soil pore volume with water (in%): | |||
| up to 50 | 25 | 10 | 10 |
| 50-80 | 50 | 25 | 10 |
| Cement-clay when filling the soil pore volume with water (in%) | |||
| up to 50 | 25 | 10 | 10 |
| 50-80 | 50 | 25 | 10 |
| Cement with plasticizing additives when more than 80% of the soil pore volume is filled with water | 50 | 25 | 10 |
| Structures located above the level of the waterproofing layer | |||
| Cement-lime at relative room humidity (%): | |||
| up to 60 | 10 | 10 | 4 |
| 60-75 | 25 | 25 | 10 |
| 75 or more | 50 | 25 | 10 |
| Cement-clay at relative room humidity (%): | |||
| up to 60 | 10 | 10 | 5 |
| 60-75 | 25 | 25 | 25 |
| 75 or more | 50 | 50 | 25 |
Cement-lime and cement-clay mortars in summer conditions are used in the construction of buildings whose height does not exceed three floors. Brand clay mortar, used in a dry climate - 10, in a moderately humid climate - 2, and for a solution with additives - 4. The consumption of binders depends on the composition of the solution (Table 5), as well as the brand of binder and solution (Table 6).
Table 5. Compositions of mortars for masonry (in parts by volume).
| Cement brand | Brand of solution | |||||
| 100 | 75 | 50 | 25 | 10 | 4 | |
| Cement-clay mortars | ||||||
| 25 | - | - | - | - | - | 1:0,2:3 |
| 50 | - | - | - | - | 1:0,1:2,5 | 1:0,7:6 |
| 100 | - | - | - | 1:0,1:2 | 1:0,5:5 | 1:0,9:7 |
| 150 | - | - | - | 1:0,3:3,5 | 1:1:9 | 1:1:9 |
| 200 | - | - | 1:0,1:2,5 | 1:0,5:5 | 1:1:9 | - |
| 250 | - | - | 1:0,2:3 | 1:0,7:6 | - | - |
| 300 | - | 1:0,2:3 | 1:0,4:4,5 | 1:1:9 | - | - |
| 400 | 1:0,2:3 | 1:0,3:4 | 1:0,7:8 | 1:1:11 | - | - |
| 500 | 1:0,3:4 | 1:0,5:5 | 1:1:8 | - | - | - |
| 600 | 1:0,4:4,5 | 1:0,7:6 | - | - | - | - |
| Cement-lime mortars for masonry in conditions high humidity (60-75%) | ||||||
| 100 | - | - | - | 1:0,1:2 | 1:0,5:5 | 1:0,7:7 |
| 150 | - | - | - | 1:0,3:3,5 | 1:0,7:9 | - |
| 200 | - | - | 1:0,1:2,5 | 1:0,5:5 | 1:0,7:9 | - |
| 250 | - | - | 1:0,2:3 | 1:0,7:6 | - | - |
| 300 | - | 1:0,2:3 | 1:0,4:5 | 1:0,7:9 | - | - |
| 400 | 1:0,2:3 | 1:0,3:4 | 1:0,7:6 | - | 1:0,7:11 | - |
| 500 | 1:0,3:4 | 1:0,5:5 | 1:0,7:8 | - | - | - |
| 600 | 1:0,4:4,5 | 1:0,7:6 | - | - | - | - |
For laying dry and porous walls stone materials They use solutions with greater mobility, and for masonry made from damp and dense materials - with less mobility.
Table 6. Consumption of binders depending on the brand of solution.
| Cement brand | Cement consumption (kg) for brand mortar | |||||||
| 200 | 150 | 100 | 75 | 50 | 25 | 10 | 4 | |
| 500 | 410 | 330 | 245 | 195 | - | - | - | - |
| 400 | 490 | 400 | 300 | 240 | 175 | - | - | - |
| 300 | - | 510 | 385 | 310 | 225 | 135 | - | - |
| 200 | - | - | - | 445 | 325 | 190 | - | - |
Before considering the question of the proportions of the cement mortar, it is still necessary to clarify the issue of the mortar itself. For any individual construction people use cement mortars, which use cement and sand. However, unlike professionals, many simply do not understand that cement mortar and solution are somewhat different things, which is why they are used differently.
The difference between cement and concrete mortar
The fundamental difference between these solutions is that if for a cement mortar, in addition to the cement itself, only sand is used, then for a concrete mortar, gravel (or crushed stone) is also used. The conversation will be about cement mortars. Therefore, as a first approximation, we can say that concrete mortar- This is a “fine-grained” cement mortar. For each “type” of work, its own composition is prepared. This depends on the purposes for which it will be used.
Each “structure” is (or will be) operated under certain conditions. Therefore, the conversation should still be conducted not about the brand of cement that is “mixed”, but about the brand of the cement mortar that should be the result. The grade of the solution is an indicator of the hardness, strength and durability of the finished “structure”. After all, you need to take into account such parameters as climatic conditions, changes in temperature, humidity, pressure. It is also important whether this place the solution will subsequently experience any loads.
Any cement mortar consists of two components – cement and sand – “mixed” with water. The technology for preparing all such solutions is the same. First of all, a dry mixture is prepared, consisting, naturally, of sand and cement. The difference between brands of cement mortars is that for each of them a certain brand of binder (cement) is taken. The second difference is in the proportions in which the components are taken. In other words, what is the relationship between the mass of cement and the mass of sand.
Types of solutions
Solutions are divided into fatty, lean and normal. Fat people are different from the norm big amount cement. Their disadvantage is rapid cracking. There is too much sand in the solution, it is difficult to work with, and its strength is low. When conducting construction work As a rule, cement mortars of grades 15, 50, 75, 100 and 150 are used.
The brands establish their ultimate strength at temperatures from 15 to 25 degrees 4 weeks after application to the surface (or pouring). There is also such a thing as “mobility” of a solution. Usually it is in the range of 4 – 15.
Purpose of solutions and proportions of various brands of cement
Cement mortars are used for plastering, masonry and construction. They differ in the quality of the sand used and the sand-cement mass ratio. For plastering walls, for example, fine-grained sand is used.
In practice, for private construction, the solution is prepared as follows: 1 part cement to 2 - 3 sand. In this case, cement should be used 300 or 400. If there is more sand, then premature destruction is possible in the future.
Solution brand 100
If the sand is fine, it is well suited for plastering and masonry work. If the cement is grade 400, then sand is 3.5 parts. And if the cement is “300” - 2.5 parts. You can use granite dust instead of sand. Ratio 1:3 with cement “400”.
Solution grade 150
Also suitable for masonry and plastering. If it is necessary to make a floor screed, the sand should be coarse-grained.
It must be borne in mind that various fillers are very often used. Adding gypsum, hydraulic lime, and clay to the solution increases its elasticity.
The strength of the solution is determined by its brand, i.e. the ability to withstand a certain compressive load, measured in kilograms per square centimeter. To obtain a solution of the same composition, all components included in it are measured in certain doses, using various dishes or scales. There are lean, normal and fatty solutions. There is a lot of filler in the skinny one, it is inconvenient to work with and does not have proper strength. A normal solution contains sufficient binder and filler, while a greasy solution contains an excess of binder, so it cracks. Fat content is determined mainly in clay and lime mortars using a paddle to mix it. If the solution does not stick to the oar, but only stains it, it is skinny; if it sticks in separate clots - normal; when the solution strongly envelops the oar, it is greasy.
Binders are added to a lean solution, and filler is added to a fatty solution. All materials used to prepare the solution are pre-screened on a sieve. When preparing a solution for plastering works use a sieve with 5x5 mm cells, for stone work - with 10x10 mm cells. A solution is prepared immediately from clay or lime paste, and from cement, a dry mixture is first prepared, and then a solution. You can make the mixture in a box; but it’s better on the striker - wooden shield 2x3 m in size. Any solution must be prepared carefully. A poorly mixed solution is inhomogeneous, and where it is weaker, structural destruction may begin. Accurate dosing of materials is mandatory. Dry mixtures, such as cement and sand, are best prepared this way. Sand and cement in the form of a bed are poured in layers, which are brought to a total height of 200-300 mm. This bed is shoveled several times until smooth, and then the mixture is sifted through a fine sieve with cells of 3x3 mm, no less.
To prepare the solution, the mixture and water are also measured in doses and thoroughly mixed until completely homogeneous. Excess water results in a thinner solution and, after drying, it is less durable than a thick solution of the same composition. Properly prepared mixtures produce solutions that are homogeneous in composition. They are much easier to install than non-uniform ones.
Materials and solutions for foundations and plinths
These parts of buildings are erected from durable materials, which can serve long time without collapsing. Tables 6 and 7 indicate materials and solutions for foundations and plinths located in different conditions operation.
Table 6. Solutions for laying foundations and plinths located below the waterproofing layer:
| Cement brand | Soil type | |||
| low-moisture | wet | saturated with water | ||
| cement-lime mortar grade "10" (cement, lime paste, sand) | cement-clay mortar grade "10" (cement, clay dough, sand) | cement-lime and cement-clay mortar grade "25" (cement, lime or clay, sand) | cement mortar grade "50" (cement, sand) | |
| 50 | 1:0,1:2,5 | 1:0,1:2,5 | - | - |
| 100 | 1:0,5:5 | 1:0,5:5 | 1:0,1:2 | - |
| 150 | 1:1,2:9 | 1:1:7 | 1:0,3:3,5 | - |
| 200 | 1:1,7:12 | 1:1:8 | 1:0,5:5 | 1:2,5 |
| 250 | 1:1,7:12 | 1:1:9 | 1:0,7:5 | 1:3 |
| 300 | 1:2,5:15 | 1:1:11 | 1:0,7:8 | 1:4,5 |
| 400 | 1:2,1:15 | 1:1:11 | 1:0,7:8 | 1:6 |
Note: The compositions of solutions are given in volumetric units.
Table 7. Materials for the underground part of the house and the basement located below the waterproofing layer:
| Materials | Material grade, kgf/cm 2 | ||
| Priming | |||
| low-moisture | wet | saturated with water | |
| at the groundwater level at a depth from the ground surface, m | |||
| 3 or more | from 1 to 3 | 1 | |
| Natural stone, weighing more than 1600 kg/m3 (limestone, dense sandstone, granite, diorite, basalt) | 100 | 150 | 200 |
| Natural stone weighing less than 1600 kg/m 3 | 50 | 75 | Cannot be used |
| Heavy concrete weighing more than 1800 kg/m 3 and products made from it, except concrete based on fuel slag | 75 | 75 | 100 |
| Clay brick of plastic pressing | 100 | 125 | 150 |
| Cement mortar | Application is not justified | 25 | 50 |
| Cement-lime mortar | 10 | 25 | Cannot be used |
| Cement-clay mortar | 10 | 25 | Same |
Rubble concrete is most often used for foundation construction. The filler is usually stone from quarries, coarse gravel, crushed stone, half-brick, broken brick, etc. The filler is laid in layers 20-25 cm thick, spaced along the walls. Each layer is watered with a solution of the desired brand and compacted tightly.
Cement-lime mortar is prepared from cement, lime paste and sand. Lime dough is diluted with water to the consistency of milk and filtered on a clean sieve. A dry mixture is prepared from cement and sand, mixed with lime milk and mixed thoroughly. Addition lime milk increases the plasticity of the solution. Instead of lime dough, you can use clay dough, which is taken in the same quantity. The compositions (in volumetric parts) and grades of cement-lime and cement-clay mortars are given in Tables 8, 9, 10. Both mortars are used both for laying above-ground walls and foundations in dry soils. If underground masonry is carried out in low-moisture soil, then for 1 m 3 of sand in cement-lime mortars take at least 75 kg of cement, in cement-clay mortars - 100 kg; in very wet and water-saturated soils - 100 and 125 kg.
Table 8. Composition and grades of cement-lime and cement-clay mortars:
| Cement brand | Brand of solution, kgf/cm 2 | ||||
| 100 | 50 | 25 | 10 | 4 | |
| Ratio of solution parts | |||||
| 400 | 1:0,2:3,5 | 1:0,7:6,5 | 1:1,9:12,5 | - | - |
| 300 | 1:0,1:2,5 | 1:0,4:5 | 1:1,3:10 | - | - |
| 200 | - | 1:0,2:3,5 | 1:0,7:6,5 | 1:2:16 | - |
| 150 | - | - | 1:0,3:4,5 | 1:0,8:7 | - |
| 100 | - | - | 1:0,1:3 | 1:1,5:10,5 | 1:1,8:13 |
| 50 | - | - | - | 1:0,2:3,5 | 1:1:9 |
Note: the numbers 1:0.7:6.5 mean that they take 1 part cement, 0.7 parts lime or clay dough and 6.5 parts sand.
Table 9. Mortar compositions for above-ground masonry of buildings with room humidity up to 60% and for laying foundations in low-moisture soils:
| Cement brand | Brand of solution | |||
| 100 | 75 | 50 | 25 | |
| 600 | 1:0,4:4,5 | 1:0,7:6 | - | - |
| 500 | 1:0,3:4 | 1:0,5:5 | 1:1:8 | - |
| 400 | 1:0,2:3 | 1:0,3:4 | 1:0,7:6 | 1:1,7:1,2 |
| 300 | - | 1:0,2:3 | 1:0,4:4,5 | 1:1,2:9 |
| Cement-clay mortars | ||||
| 600 | 1:0,4:4,5 | 1:0,7:6 | - | - |
| 500 | 1:0,3:4 | 1:0,5:5 | 1:1:3 | - |
| 400 | 1:0,2:3 | 1:0,3:4 | 1:0,7:6 | 1:1:11 |
| 300 | - | 1:0,2:3 | 1:0,4:4,5 | 1:1:9 |
Table 10. Compositions of mortars for above-ground masonry with a room humidity of more than 60% and for foundation masonry located below the groundwater level:
| Brand | Brand of solution | |||
| 100 | 75 | 50 | 25 | |
| Cement-lime mortars | ||||
| 600 | 1:0,4:4,5 | 1:0,7:6 | - | - |
| 500 | 1:0,3:4 | 1:0,5:5 | 1:0,7:8 | - |
| 400 | 1:0,2:3 | 1:0,3:4 | 1:0,7:6 | - |
| 300 | - | 1:0,2:3 | 1:0,4:5 | 1:0,7:9 |
| Cement-clay mortars | ||||
| 600 | 1:0,4:4,5 | 1:0,7:6 | - | - |
| 500 | 1:0,3:4 | 1:0,5:5 | 1:0,7:7,5 | - |
| 400 | 1:0,2:3 | 1:0,3:4 | 1:0,7:6 | 1:0,7:8,5 |
| 300 | - | 1:0,2:3 | 1:0,4:5 | - |
| Cement mortars | ||||
| 600 | 1:4,5 | 1:6 | - | - |
| 500 | 1:4 | 1:5 | - | - |
| 400 | 1:3 | 1:4 | 1:6 | - |
| 300 | - | 1:3 | 1:4,5 | - |
Cement mortars are prepared in the following sequence. A dry mixture is first prepared from cement and sand, and for 1 part of cement you can take from 2.5 to 6 parts of sand (depending on the brand of cement). The dry mixture is mixed with water, mixed and used for 1-1.5 hours. Cement mortars are most often used for laying foundations and other structures that are located below the groundwater level. Walls can also be laid on the same mortars. They are quite durable, but very cold. Depending on the brand of binder material and the amount of filler taken in volumetric parts, a cement mortar of one or another brand is obtained (Table 11). The need for cement is determined depending on its brand and the brand of the prepared solution (Table 12).
Table 11. Brand of mortar depending on the brand of cement and amount of filler:
| Cement brand | Brand of solution, kgf/cm 2 | ||||
| 100 | 50 | 25 | 10 | 4 | |
| Ratio of solution parts | |||||
| 400 | 1:3,5 | 1:6 | - | - | - |
| 300 | 1:2,5 | 1:5 | - | - | - |
| 200 | - | 1:3,5 | 1:6 | - | - |
| 150 | - | 1:2,5 | 1:4 | 1:6 | - |
Table 12. Cement consumption per 1 m 3 of sand to prepare a solution of the required grade:
| Cement brand | Brand of solution, kgf/cm 2 | ||||
| 100 | 50 | 25 | 10 | 4 | |
| Cement consumption, kg | |||||
| 400 | 340 | 185 | 90 | - | - |
| 300 | 435 | 240 | 120 | - | - |
| 200 | - | 350 | 185 | 75 | - |
| 150 | - | - | 230 | 95 | - |
Cement - artificial inorganic binder material, which when adding water, saline aqueous solutions, other liquids forms a plastic mass, which subsequently hardens, turning into a stone-like body.
Used for the production of concrete and mortars. Now the most popular brands are M (PC) 400 and M500.
Purchasing high-quality binding material
- It is better to make a purchase in specialized construction stores and supermarkets, not at the market.
- It is necessary to carefully examine the integrity of the packaging and all inscriptions. It is very important that the storage period does not exceed six months. The fresher the better. And to avoid counterfeiting, you need to check the quality certificate.
- The presence of lumps is unacceptable, and folk method quality control is as follows: take a handful of cement and clench your palm into a fist. If it seeps through your fingers, then the material is good, but if it becomes compact in your hand, you should not take it.
- It is not recommended to store it for future use; it is advisable to use it immediately after purchase, and if a certain amount remains after the work has been done, it must be stored strictly in a place protected from moisture, additionally placing it in sealed containers. plastic bags tying them tightly.
Proportions for preparing mortars
Many people think that the M400 or M500 brand is an indication of what proportion should be followed to prepare the mixture. This is wrong. The number indicates that the cement can withstand a load of 400 or 500 kg/cm2, respectively. How to dilute cement?
The tables of the Instructions for the preparation and use of mortars CH 290-74 indicate strictly regulated proportions.
So solutions are divided into:
- Plaster mortars: grades M10, M25, M50;
- Masonry mortars: grades M50, M75, M100, M125, M150, M200;
- for screed: grades M150, M200.
- Mix water with binder to obtain cement laitance, to which sand is added.
- The second option is preferable: first mix cement with sand, and then add water. This guarantees the homogeneity of the resulting cement mass and the quality of construction work.
When preparing a cement-lime or cement-clay mortar, first the lime (clay) dough is diluted with water to the consistency of milk and passed through a sieve with 10x10 mm cells. Then add it to the already mixed mixture of sand and binder.
For plastering work, clean river sand is used; for masonry, you can also use quarry sand. Before use, the sand is sifted through a sieve with 10x10 mm cells. Often in individual construction, old armored mesh from a bed is used for these purposes.
The amount of water is determined during the production of the mixture, judging by the consistency of the mixture.
To mix the solutions manually, use a shovel or a construction mixer. But it is still better to purchase for large volumes of construction work electric concrete mixer. To deliver the solution, use ordinary buckets, stretchers or a wheelbarrow. Don't forget about gloves and safety glasses.