Mortars in construction are a necessary material for the construction of any buildings: both large and light. These mixtures are divided into several types: mortars are prepared on a cement, lime or gypsum basis, and these substances can also be combined.
There is a gradation according to quality indicators, according to the proportions of the binder component and filler, as well as other characteristics.
Types of mortars and their composition
Construction mortar (GOST 5802-78) is a mixture of binder and aggregate (sand) with water. This mixture has the main property of hardening after installation. The mortar is used to bind individual bricks, blocks, stones, etc. together.
The strength of such a bond depends on the quality of the solution used. The use of mortars in construction depends on the building material used: for each material it is necessary to use a certain type of mortar.
When constructing showers and toilets, various solutions are used. Depending on the binder included in the mortar, they can be divided into several groups. The main types of mortars in construction are cement, gypsum, lime and combined.
Cement mortars are prepared on the basis of cement or Portland cement. The main component of gypsum solutions is gypsum. Lime mortars contain air or hydraulic lime.
Combined mortars can be prepared on the basis of gypsum and lime, cement and clay, cement and lime, etc.
Lime has more pronounced astringent properties, so all other components are equated to its volume.
To use mortars in construction, it is not always possible to prepare high-quality material, guided only by the quantitative ratio of binders and filler, since in addition to such a ratio, it is also necessary to take into account the basic properties of the components, i.e. fat content, brand, amount of impurities, etc. .
Simple and complex mortars for construction and their proportions
The durability of the design of the summer shower and toilet and their finishing largely depends on the quality of the prepared solution. There are simple and complex mortars for construction: a simple one consists of one binder component and a filler (lime, clay, cement), and a complex one consists of two binder components and a filler (cement-lime).
For simple solutions, designations are used where the mass part of the binder component is indicated in the first place, and the mass part of the filler in the second place (1: 5, etc.).
In complex solutions, the mass parts are indicated in the following sequence: binder, lime paste, filler. The optimal proportions of complex mortars for construction are 1:1:6. The introduction of several binder components affects the structure and properties of the solution. The addition of clay gives greater plasticity to the cement mortar, that is, it acts as a plasticizer.
In complex solutions, the volume of the main binder component is conventionally taken as one. The remaining substances are designated by numbers that indicate how many parts by volume are needed per part of the main binder component. The main astringent component has more pronounced astringent properties compared to other substances included in this solution. Therefore, the name of the solutions is given according to the name of the main binder. For example, the lime-clay mortar contains two binders - lime and clay.
Fat and lean mortars
There are fatty, lean and normal mortars for construction: each of them has properties that make them suitable or unsuitable for construction work. Fatty solutions are more plastic, but are prone to cracking.
Lean solutions are too hard and therefore do not have sufficient strength. When constructing a summer shower and toilet, it is recommended to use normal mortars, since they have sufficient plasticity and do not crack when drying, and their shrinkage is minimal. To determine the fat content of the solution, just look at the paddle with which it is mixed. If the solution only stained the oar, then the solution is thin. Slightly adhering grout is normal, but heavily adhering grout indicates that it is greasy.
Solutions can be divided into heavy ones, whose dry density is more than 1500 kg/m3, and light ones, whose density does not exceed 1500 kg/m3.
According to their intended purpose, mortars are divided into masonry mortars (intended directly for laying brick, stone and stove blocks), finishing mortars (for finishing stoves) and special ones.
Brands of mortars by strength and mobility
Like brick, cement and others used in construction, mortars differ in brand. It is determined depending on the ability of the solution to withstand compressive load. There are the following brands of mortars for masonry: 0, 2, 10, 25, 50, 75, 100, 150, 200. For the construction of a summer shower and toilet, only mortars of grades 150 and 200 are suitable. The strength indicator of the mortar brand is established experimentally using testing a cube of it measuring 70 X 70 mm on the 25th day at a temperature of about 20°C. To do this, samples must be taken at different stages of the batch (at the beginning, middle and end).
To uniformly fill vertical and horizontal joints with masonry mortar, it is necessary that it be sufficiently mobile and able to retain moisture. It is clear that these properties depend on the characteristics and ratio of the components. For different jobs, different brands of mortars are used in terms of mobility: it can be measured by the depth of immersion of a standard cone, which has certain parameters, into the solution. The deeper the cone is immersed, the more mobile the solution is considered. The masonry mortar has a mobility of 9-13 cm for ordinary clay bricks, 7-8 cm for hollow bricks, 13-15 cm for rubble masonry and 5-7 cm for plastering.
Composition of lime mortar for construction
This solution is prepared from lime paste (1 part), obtained from lime and water, and river sand (2-4 parts). Pour sand into the lime dough while stirring constantly. Mix everything well until a mass of homogeneous consistency is obtained. If the solution sticks to the spatula, it means that it is too greasy.
The degree of fat content can be reduced by introducing an additional amount of sand. If the resulting solution cannot be kept on the spatula when scooping, then add lime. Lime mortar is used for interior plastering work, since it is a low grade mortar. It does not create problems in operation, since it is characterized by ease of installation and good adhesion.
Cement mortar: composition, properties and preparation
Due to their composition and properties, cement mortars are the most durable; they are capable of hardening both in air and at high humidity and even in water. The beginning of setting of cement mortars begins after approximately 30-40 minutes, and final hardening occurs after 10-12 hours. Due to the high strength properties of cement mortars and their moisture resistance, these materials are used for the construction of capital walls, foundation laying, and the construction of elements of street buildings, most often located in conditions of high humidity or in areas of strong changes in humidity.
When laying a foundation on wet soil and erecting the walls of a summer shower, it is recommended to use mixed cement mortars. They most often consist of two binding elements and a filler. An example of such a solution would be a mixture of cement, lime paste and sand. When hardened, such a solution has high strength and moisture resistance. To prepare it you will need 1 part cement, 2 parts lime paste and 6 to 12 parts sand.
To prepare a standard cement mortar, you need to take cement (1 part), river sand (2-5 parts) and water. The ingredients must be combined and then mixed thoroughly. The solution obtained in this way should be used for its intended purpose within an hour. If it is necessary to obtain a particularly plastic mass, it is recommended to reduce the amount of sand to 2-3 parts.
Cement mortar is used for laying walls in winter conditions using the freezing method, erecting walls whose thickness does not exceed 25 cm, and foundations. In addition, cement mortar is recommended for the construction of walls with lightweight brickwork and walls in rooms with high humidity levels.
To obtain cement mortar, cement and sand must be mixed dry and then mixed with water.
Cement-lime and clay mortars: composition, application and how to prepare
The composition of the cement-lime mortar includes cement (1 part), river sand (6-8 parts) and lime dough (2 parts). To prepare it, you first need to combine and mix sand and cement, then add lime paste to the resulting mixture and mix everything thoroughly again until a viscous mass of uniform consistency is obtained. The use of complex cement-lime mortar is recommended for construction work under normal conditions; it is mainly suitable for plastering a yard toilet.
The composition of the lime-clay mortar includes clay dough (1 part) and lime dough (0.4 parts), as well as river sand (4-5 parts). The lime dough must be mixed with the clay dough, and then dry sand must be added to the resulting mixture with constant stirring. After this, you should mix everything and use the solution for its intended purpose.
Compared to cement-lime mortar, cement-clay mortar is considered more durable and quick-setting. In addition, it is easy to transport, as it does not delaminate when shaken.
Cement-clay mortar can be used when working in winter conditions, since the clay retains moisture, which, when defrosted, increases the strength of the mortar. The clay should have a finely ground structure. It should be added in equal proportions with cement.
How to prepare clay mortar for the construction of light structures? To prepare a lime-gypsum-clay solution you will need gypsum (1 part), clay-lime composition (3-4 parts) and water. A large, deep bowl should be filled with water, then pour gypsum into it and mix quickly, then add the clay-gypsum mixture. After this, everything should be thoroughly mixed until a homogeneous mass without lumps is obtained.
Lime-gypsum mortar has higher strength characteristics than lime mortar.
Depending on the type of work, different amounts of solution will be required.
Cement mortar- This is probably the most important element in quality construction. At first glance, it seems that preparing such a mixture is as easy as shelling pears. By and large, this is a correct assumption. But, to obtain a first-class cement mortar, you should be very careful in selecting the component composition and optimal proportions. Before learning the intricacies of obtaining such a building material, let's find out the functions of each of the components in its formation. Online calculation of the composition of cement mortar.
From a technical point of view, the basis of the solution is water. Therefore, it is better to take clean water without any impurities. The filler in the solution is sand, and cement binds all the components together. In the process of receiving cement mortar you need to carefully approach the issue of sand quality. Firstly, you should make sure that there is no clay or other rocks or debris. Secondly, choose the right sowing of sand. For example, fine sand is best used for brickwork, while coarse sand in plastering may require additional sanding or leveling.
When choosing cement, you need to take into account some of its features. Firstly, if stored for a long time, even unopened cement can harden and become unusable. Therefore, it would be wiser to buy cement before starting work. Secondly, cement should only be in paper packaging. It is important to choose the right brand of cement depending on the type of construction work. For example, cement with a grade lower than M300 cannot be used for the foundation.
Let's consider recommendations and cooking standards cement-sand mortar depending on the type of work. Cement grade M400 is used in the construction of massive solid buildings, you need to use cement M400. If you mix cement M400 and sand in a ratio of 1:2, you get the composition M200. For finishing work and preparing the surface for cladding, it is advisable to use M400 or M500 cement, sand and water for the mixture in a ratio of 1:3:0.5. If you increase the relative proportion of cement in the solution, you can reduce the hardening time of the plaster. Also, good results are obtained with a ratio of cement, sand and lime milk of 1:5:2 in plastering work, and for floor screed - with a ratio of 1:2-1:6. When building ordinary standing buildings, the optimal ratio is from 1:3 to 1:6. In everyday life, popular proportions are 1:3 and 1:4.
Properties of cement mortars.
When working with brick, for example, grade 75 is perfect cement mortar grade 75 (working proportions 1:5:3.) Brickwork can also be given a certain color by adding soot to the solution. It should be taken into account that a large amount of soot leads to a decrease in the strength characteristics of the cement mortar.
A problem often arises when, after adding the required proportion of water to cement mortar it loses a lot in mass density. To increase the viscosity of such a mixture, you need to add a little cement and sand, maintaining the ratio of their parts.
Optimal for tile finishing work cement-sand mortar ratio 1:2.4:0.4. When performing such work, it is important to control the density of the mixture. This is very easy to do. Spread a small volume of the solution in an equal layer on the back side of the tile and try to shake it off. If after such manipulations a layer more than 3 mm thick remains on the tile, then the prepared high-quality solution is prepared. When the mixture completely falls off the surface, it is worth increasing its density slightly (just add sand and cement according to the selected proportion). It is also technologically advanced to properly moisten the working side of the tile with cement milk (1 part cement to 3-4 parts water).
For cooking cement-lime mortar Cement and lime (binders), sand (filler), and water are used. It is very important to take fresh cement, since long-term storage significantly deteriorates its properties. So, for example, after a month of storage, the M500 brand is reduced in characteristics to M450. Moreover, within six months of storage, cement can lose up to ¼ of its useful qualities. The sand fraction should be 3-5 mm. In this case, both river and quarry sand are suitable. For example, for plaster, sand from a quarry is preferable, since the admixture of clay it contains makes the mixture much softer. To increase the elasticity of the solution, it is often practiced to add PVA glue in a ratio of 0.5 liters of glue per 20 liters of working solution. Instead of glue, you can add liquid soap (0.2 liters per 20 liters of solution) and plasticizers.
It is worth noting that the ratio of the components of the cement-lime mortar is influenced by the type of work performed. For example, it is better to plaster cement mortar with a ratio of 1:1:6 or 1:2:9.
Makes it much easier to calculate the volume of components for cement mortar and the selection of the appropriate brand of cement are special tables. Such tables also exist for the preparation of sand-cement mortar, taking into account the type of soil, and they can be easily found on the Internet.
The table contains the ratios of components for various cement-lime mortars.
To obtain high-quality masonry cement mortar It is optimal to use pre-sifted sand. Sifting on a special construction sieve allows you to get rid of unnecessary stones, soil and other unnecessary impurities.
Makes the process much easier obtaining cement mortar concrete mixing machines. The sequence of adding components to the mixer is as follows: first add part of the required volume of water, and then, successively, cement and sand. At the end, pour out the remaining water. The mixing process itself lasts at least 2 minutes. After this time, you can pour the solution into a bucket or other working vessel. It must be remembered that the cement mortar hardens quickly, so you should not prepare a very large amount of it. The optimal amount of cement mortar is one that can be consumed in a few hours of work. And also do not forget about periodic mixing of the masonry cement mortar to avoid its delamination.
Solutions are a homogeneous mass or mixture consisting of two or more substances, in which one substance acts as a solvent and the other as soluble particles.
There are two theories for interpreting the origin of solutions: chemical, the founder of which is D.I. Mendeleev, and physical, proposed by the German and Swiss physicists Ostwald and Arrhenius. According to Mendeleev's interpretation, the components of the solvent and the dissolved substances become participants in a chemical reaction with the formation of unstable compounds of these same components or particles.
The physical theory denies the chemical interaction between the molecules of the solvent and the dissolved substances, explaining the process of formation of solutions as a uniform distribution of particles (molecules, ions) of the solvent between the particles of the dissolved substance due to a physical phenomenon called diffusion.
Classification of solutions according to various criteria
Today there is no unified system for classifying solutions, however, conditionally, types of solutions can be grouped according to the most significant criteria, namely:
I) Based on their state of aggregation, they are divided into: solid, gaseous and liquid solutions.
II) According to the size of the particles of the dissolved substance: colloidal and true.
III) According to the degree of concentration of the particles of the dissolved substance in the solution: saturated, unsaturated, concentrated, dilute.
IV) According to their ability to conduct electric current: electrolytes and non-electrolytes.
V) By purpose and area of application: chemical, medical, construction, special solutions, etc.
Types of solutions by state of aggregation
The classification of solutions according to the aggregative state of the solvent is given in the broad sense of the meaning of this term. It is customary to consider liquid substances as solutions (and both a liquid and a solid element can act as a soluble substance), however, if we take into account the fact that a solution is a homogeneous system of two or more substances, then it is quite logical to recognize also solid solutions and gaseous. Solid solutions are considered to be mixtures, for example, of several metals, more commonly known as alloys. Gaseous types of solutions are mixtures of several gases, an example is the air around us, which is presented in the form of a compound of oxygen, nitrogen and carbon dioxide.
Solutions by size of dissolved particles
Types of solutions based on the size of dissolved particles include true (ordinary) solutions and B. The solute disintegrates into small molecules or atoms, similar in size to solvent molecules. At the same time, true types of solutions retain the original properties of the solvent, only slightly transforming it under the influence of the physicochemical properties of the element added to it. For example: when table salt or sugar is dissolved in water, the water remains in the same state of aggregation and the same consistency, almost the same color, only its taste changes.
Colloidal solutions differ from ordinary ones in that the added component does not completely disintegrate, preserving complex molecules and compounds, the sizes of which significantly exceed the solvent particles, exceeding the value of 1 nanometer.
Types of solution concentrations
You can add different amounts of the dissolved element to the same amount of solvent, and the output will be solutions with different concentrations. We list the main ones:
- Saturated solutions are characterized by the degree to which the soluble component, under the influence of a constant temperature and pressure, no longer disintegrates into atoms and molecules and the solution reaches phase equilibrium. Saturated solutions can also be divided into concentrated ones, in which the dissolved component is comparable to the solvent, and dilute ones, where the dissolved substance is several times less than the solvent.
- Unsaturated solutions are those in which the solute can still disintegrate into small particles.
- Supersaturated solutions are obtained when the parameters of the influencing factors (temperature, pressure) change, as a result of which the process of “crushing” the dissolved substance continues, it becomes larger than it was under normal (usual) conditions.
Electrolytes and non-electrolytes
Some substances in solutions break down into ions that can conduct electric current. Such homogeneous systems are called electrolytes. This group includes acids and most salts. And solutions that do not conduct electric current are usually called non-electrolytes (almost all organic compounds).
Groups of solutions by purpose
Solutions are indispensable in all sectors of the national economy, the specificity of which has created such types of special solutions as medical, construction, chemical and others.
Medical solutions are a set of preparations in the form of ointments, suspensions, mixtures, solutions for infusions and injections and other dosage forms used for medical purposes for the treatment and prevention of various diseases.
Types of chemical solutions include a huge variety of homogeneous compounds used in chemical reactions: acids, salts. These solutions can be of organic or inorganic origin, aqueous (sea water) or anhydrous (based on benzene, acetone, etc.), liquid (vodka) or solid (brass). They have found their application in a wide variety of sectors of the national economy: chemical, food, textile industries.
Types of mortars have a viscous and thick consistency, which is why the name of the mixture is more suitable for them.
Due to their ability to quickly harden, they are successfully used for laying walls, ceilings, load-bearing structures, as well as for finishing work. They are aqueous solutions, most often three-component (solvent, cement of various markings, filler), where sand, clay, crushed stone, lime, gypsum and other building materials are used as filler.
1. Simple:
- when mixing sand with lime milk, a lime mortar is obtained (the ratio of lime and aggregate can be different: 1: 1; 1: 1.5; 1: 2; 1: 2.5; 1: 3; 1: 3.5; 1: 4 ), which is characterized by workability and good adhesion to the masonry material. As a rule, such solutions have low grades and are used for plastering internal surfaces and when laying walls of low-rise buildings;
- The binder in gypsum solutions is building gypsum. Such solutions are used for laying walls and partitions built from gypsum stones and slabs;
- Cement mortars are used when laying foundations, walls with a thickness of no more than 250 mm and walls made using lightweight masonry. In addition, they are used for laying walls in winter using the freezing method, as well as in rooms with high humidity. In private housing construction, cement mortars are not recommended for wall masonry. The exception is the cladding masonry, which is more exposed to natural climatic factors, and the walls themselves are built using complex or lime mortars.
2. Difficult:
- To increase the strength of the lime mortar, cement is added to it. Their main purpose is masonry of internal walls, plastering of basement walls (for masonry work carried out below the groundwater level, these solutions are not used). To obtain a cement-lime mortar, such an amount of water is added to the lime dough to form lime milk, which is used to mix the mixture of sand and cement (they are combined dry and mixed thoroughly). Depending on the degree of humidity of the building under construction, the proportions of cement, lime paste and sand change.
As a result, the solution becomes more plastic and “warm” (it can be used to plaster walls to increase their heat-insulating properties, hence the name “warm plasters”); - Cement-clay mortars are more durable than cement-lime mortars (cement to clay ratio 1:1). In addition, they are distinguished by rapid setting and are less prone to delamination during transportation. Such solutions are convenient to use in winter, since clay, having the ability to retain water, increases the strength characteristics of the solution when it thaws.
By way of information
So, mortar is a mixture of sand, binder and water. Their main part is sand, the particle size of which is no more than 4 mm. When preparing a mixture, the components of the solution are measured in volumetric parts. In order not to disturb the proportions, the volume measures must be the same. For example, there is more wet sand in a bucket than dry sand. Only clean fresh water should be used for the solution.
In cases where a large amount of solution is required, it is more profitable to prepare it yourself using a concrete mixer. If the amount of work is small, then it is cheaper and more convenient to purchase dry construction mixture. In this case, you do not need to buy, measure, or mix individual components - just pour into the mixture as much water as indicated in the instructions, and using a special mixer (or a drill with an attachment) bring it to a homogeneous state. Construction mixtures are compiled by highly professional specialists, therefore, a solution prepared from such a composition will be of appropriate quality.
Construction mortars are classified according to the type of binder, volumetric mass and purpose.
By type of binder Mortars are divided into cement, lime, gypsum and mixed. Solutions can also be made using non-clinker binders (lime-slag, lime-pozzolanic, etc.). The most widely used solutions are cement and gypsum binders.
Depending on dry volumetric weight solutions are divided into ordinary (heavy) with a volumetric mass of 1500 kg/m 3 or more, made with ordinary dense aggregates, and light with a volumetric mass of less than 1500 kg/m 3, prepared with light aggregates.
By purpose There are finishing mortars, for masonry and the construction of walls from large elements, as well as special ones.
Mortar mixtures are prepared in the form of ready-made solutions of the required mobility and dry mixtures (dry construction mixtures), which require mixing with water before use. If necessary, chemical additives are introduced into ready-made mortars to adjust the properties of the mortars.
Depending on the basic properties, the following grades of solutions are used: for compressive strength (kg/cm2) 4, 10, 25, 50, 75, 100, 200 and 300; by frost resistance (Mrz), based on the number of cycles of alternating freezing and thawing maintained: 10, 15, 25, 35, 50, 100, 150, 200 and 300.
Solutions M 4, 10 and 25 are prepared mainly with lime and less often with clinker-free binders. The compositions of mortars for obtaining a given grade can be selected in any reasonable way that ensures the production of a given grade of mortar by a certain hardening time with the lowest consumption of binder. In this case, the mobility and water-holding capacity of the mortar mixture must be obtained, corresponding to the area of application of the solution.
Finishing mortars are divided into decorative and ordinary plaster. Decorative colored solutions are used for factory finishing of the front surfaces of wall panels and large blocks, as well as for external and internal plastering of buildings. For finishing panels made of heavy concrete, mortars of a grade of at least 150 are used, and for panels made of lightweight concrete and plaster of building facades - at least 50 with a frost resistance of more than 35. The compressive strength of the mortar on the day of shipment of the panels from the manufacturer must be at least 70% of its design strength. Ordinary and white Portland cements and pigments are used as a binder for decorative mortars used in finishing panels made of regular and lightweight concrete; in mortars for colored exterior plasters - the same types of cements and lime, in mortars for colored plasters inside the building - lime and gypsum. Washed quartz sand and sand obtained by crushing rocks such as granite, marble, tuff, limestone, etc. are used as fillers for the preparation of decorative colored plasters.
To obtain high-quality surfaces of products, domestic scientists have developed a colloidal solution prepared from Portland cement M400 - 20% (by weight), ground sand - 65% and ground lime - 15% with a water-solid ratio W/T = 0.6-0.7. Grinding of the dry mixture of materials for such a solution to a fineness of at least 3000 cm 2 /g is carried out in the SMZh-238 installation based on the M-400 vibrating mill, and its preparation is in the SMZh-188 mixer.
Conventional plaster solutions are used for interior and exterior finishing of buildings and structures, as well as panels and volumetric elements. They must have the necessary mobility, have good adhesion to the base and a small change in volume during hardening. The binder in conventional plaster mortars can be Portland cement, lime, gypsum and their mixtures (for example, cement-lime and lime-gypsum), and the filler can be quartz or dolomite sand with a maximum particle size of 1.2-2.5 mm. Perlite sand is also used for gypsum plaster mortars. The mobility of plaster mortars, characterized by the immersion depth of the standard StroyTsNIIL building, is assumed to be 6-12 cm.
Masonry mortars are used for masonry of bricks and small blocks, as well as for the installation of large-sized wall and other structures. For masonry of structures operating under conditions of exposure to aggressive and flowing waters, solutions based on pozzolanic and sulfate-resistant Portland cement are used. The mobility of masonry mortars, depending on the method of transportation (in bunkers or mortar pumps) and the method of laying (manually, by vibration), is assumed to be 1-14 cm. The largest sand grain size for masonry mortars for various purposes is 2.5-5 mm.
Special types of solutions, which include waterproofing, grouting, acoustic, and X-ray protective solutions, are in most cases prepared directly on the construction site from dry mixtures.
- Concrete science
- Concrete and mortars
- Classification and scope of solutions
- Concrete and mortars