solution mixtures. Interesting and necessary information about building materials and technologies

Foreword

Mortars and mastics – necessary materials for facing and other construction works.

Content

Mortars and mastics are necessary materials for facing and other construction works. The main types of mortars include solutions for floor screed, filling joints, interlayers of mosaic floors. There are also special solutions for waterproofing. Below is information on the composition of each of them and on the main characteristics of solutions and mastics.

Groups of mortars and mastics

Building mixture- it is a mixture of inorganic binder, fine aggregate and water selected in a certain way. In certain cases, inorganic or organic additives are added.

Mortars are divided into the following groups:

• heavy, the average density of which in a dry state is more than 1500 kg / m3 (quartz sand is used in the manufacture);
• light, the average density of which in a dry state is less than 1500 kg / m3 (light porous sand is used in the manufacture).

According to the type of binders that make up the mortar, the following groups are distinguished: cement, lime, gypsum and complex (cement-lime, cement-clay, lime-gypsum, etc.).

Three groups are distinguished by names: masonry, finishing and special.

Mastics consist of an adhesive composition and a solvent with the addition of finely ground natural or polymeric materials.

Mastics are hot and cold. Hot mastics are used in a heated molten state, cold mastics do not require preheating.

The thickness of the layer of mastic is 0.5-5 mm, and the mortar mixture is 15-20 mm.

Water used for the preparation of mortars and water-based mastics should not contain mechanical, chemical or other impurities that prevent or slow down the hardening of the binder. Typically, the usual drinking water, as well as natural water with a pH value (water reaction) of at least 4 and not more than 12.5 (at pH 7, the water reaction is neutral, pH<7 - кислая, pH >7 - alkaline).

Basic properties of mortars

Workability- the ability of the mortar mixture to fit on the surface thin layer. This one of the main properties of mortars depends on mobility and water-holding capacity.

Mobility of the mortar mixture (consistency)- the ability to spread under the action of its own mass or external forces applied to it. It is determined by immersing a reference cone in the solution, the mass of which is 300 g. On the outer surface of the cone, every 10 mm, risks should be applied. The cone is lowered into the freshly prepared solution, where it sinks under its own weight. The depth of immersion of the cone, expressed in centimeters, characterizes the degree of mobility of the solution.

Water holding capacity- this is the property of all types of mortars to retain water when laying it on a porous base and not delaminate during the transportation process.

To improve properties such as mobility and water-holding capacity in mortars, organic plasticizing and inorganic dispersed additives are introduced into the composition. Organic additives include soap naphtha and wood pitch, while inorganic additives include lime, clay, ash, etc.

The stratification of the mortar mixture- its heterogeneity in thickness, which occurs during storage, transportation or vibration of the mixture.

Strength. Depending on the tensile strength, the compressive strength of the prepared samples in the form of a cube determines the grade of the solution. The average tensile strength is calculated as the arithmetic mean of the test results of 5 specimens. Loss of strength when testing samples for frost resistance should not exceed more than 25% with a weight reduction of not more than 5%.

Depending on the number of withstand cycles of alternate freezing and thawing, the brand of the solution is determined by frost resistance (mrz).

Cement mortars for floor screeds and grouting joints between tiles

Floor screeds are called layers that form a rigid or dense crust over non-rigid or porous elements of the floor or ceiling. Screeds are arranged either to level the surface of the floor or ceiling, or to give the coating the required slope.

Screeds can be concrete or mortar. The strength grade of cement mortars for floor screeds is set by the project, but must be at least 150. The mobility of mortars for floor screeds is 4-5 cm.

The brand of cement mortars for filling the joints between tiles should be at least 150. The mobility of the mortar is 5-6 cm.

Sand should not contain more than 3% by weight of dust and clay particles. The use of Portland cement and aluminous cement is allowed. It is also recommended to introduce surfactants into the composition of cement mortars for filling joints. The water-cement ratio of the solution should not go beyond 0.45-0.5.

Compositions of cement mortars and dry cement mixtures

Table "Composition of cement mortar and its application":

For facing works in which cement mortars are used, it is advisable to use dry cement mixtures. Solutions are prepared on site in the right quantity and with regard to the exact dosage, which significantly saves materials and prevents losses.

Table "Composition of dry cement mixtures for facing works":

The dry mixture for the preparation of colloidal cement adhesive CCC consists of Portland cement (grade 400) and quartz sand, with a ratio of these substances of 7: 3 by weight. PRS should be used as a plasticizing additive.

KCC glue is used for finishing finished reinforced concrete products with a textured layer based on white and non-ferrous metals with marble chips and chips from other natural stone materials. To avoid microcracks in the textured layer during the preparation of the solution, 1.5 parts of sand by weight are added to 1 part of dry CCC.

The dry mixture is mixed with water immediately before use.

The adhesion strength of the CCC adhesive with the base reaches 3 MPa, and when compressed at 7 days of age - 55 MPa.

The composition of solutions for the interlayer of floor screeds and mosaic coatings

Solutions for interlayer of screeds and mosaic mosaic (terrazza) coatings are made from white or bleached ordinary cements, and in the production of colored coatings, pigments are added in an amount of not more than 15% by weight.

For ordinary cement, stone powder made from white or light-colored stone materials can be used as a thinner. The particle size in the mosaic solution should not exceed 0.15 mm, and the compressive strength should not exceed 20 MPa. The amount of thinner should not be more than 20-40% by weight of the cement.

Table "Composition of mosaic flooring mortar":

Gypsum and lime are not used as a cement thinner. The brand of bleached cement should not be lower than 300.

Sand and chips (fine gravel) used in mortars for mosaic floors are made from polished hard rocks(marble, granite, basalt). The compressive strength of these substances must be at least 60 MPa. The crumb size should not exceed 15 mm and 0.6 of the thickness of the mosaic coating.

The mobility of the mosaic solution during laying is 2-4 cm. The grade is accepted according to the project, but should not be lower than 20 MPa.

The color, tone and strength of the selected compositions are tested on prototypes.

Table "Technical characteristics of colored mosaic compositions":

Acid-resistant solutions based on liquid glass and their composition

Solutions based on liquid glass are used in case of exposure to oils and aggressive acids on the surface of the cladding. Such solutions are not waterproof, therefore hardening should take place for at least 10 days in dry conditions without water and acids getting on the surface.

Acid-resistant solutions consist of sodium silicofluoride, aggregates and liquid glass. As aggregates, finely ground or dust-like acid-resistant materials are used (for example, diabase, andesite, beshtaunit, granite, clinker, etc.). The compressive strength of aggregates should not be less than 80 MPa, acid resistance - not less than 94%, humidity - not more than 2%. In solutions with liquid glass, it is allowed to use ground quartz sand, natural powdered quartz and acid-resistant cement.

Sodium fluorosilicate must be finely ground. Humidity should be less than 1% and Na2SiF6 content should be more than 93%.

The acid-resistant solution is closed with liquid glass, the density of which is 1.36-1.45 g / cm3, and the modulus is 2.31-3. It is allowed to use liquid glass from silicate lumps. The mobility of the solution is 2-4 cm.

Table "Composition of acid-resistant solutions for interlayers and filling joints in coatings made of piece materials (% by weight)":

Additives in cement mortar for surface waterproofing

For cement waterproofing, a cement mortar is used with the addition of chemical sealants or hydrophobic additives (such as bituminous emulsions, ceresite, sodium aluminate, organosilicon compounds).

The grade of waterproofing solutions for cement surfaces must be at least 75 in strength and withstand the following hydrostatic pressure: 1 hour after laying - 0.1 MPa, a day later - 0.5 MPa. The mobility of the solution is 4-5 cm.

Table "Additives in cement mortar for waterproofing (wt. h.)":

Bituminous hot and cold floor mastics

Bituminous floor mastics are used for flooring made of piece materials (for example, ceramic tiles). Mastics are used to fix tiles and fill the joints between them.

Table "Composition of mastics for filling joints between ceramic tiles (wt. h.):

Table "Composition of hot bituminous mastics on black binders (% by weight)":

Cold bituminous mastics are a colloidal solution of petroleum bitumen in organic solvent(naphtha, kerosene, green petroleum oil, etc.).

Table "Composition of cold bituminous mastics (% by mass)":

Mastics based on synthetic resins and varnishes are used for fixing ceramic and glass tiles. They also serve as fillers for joints between tiles.

For the sphere of construction services, such a concept as building mortars is typical and familiar. GOST 28013 (approved and put into effect by the Decree of the State Construction Committee of the USSR No. 7 in 1989; it was replaced by a similar GOST, approved by the Decree of the Gosstroy of Russia No. 30 of 1998 and put into effect in July 1999) interprets the concept as a set of terms "mortar mix", "dry mortar mix", "mortar" and defines uniform requirements to general technical characteristics regarding their preparation, acceptance and transportation and quality indicators.

As a note: these standards do not apply to heat and chemical resistant mortars.

What is a mortar?

The composition of the solution is correctly arranged and thoroughly mixed to a homogeneous mass components: binder, fine aggregate and sealer. If necessary, special additives can be added to the solution. Traditionally, cement, gypsum or lime is used to give the solution elasticity. The filler, as a rule, is sand, the sealer is water.

A mortar that does not require hardening, completely ready for use after connecting the necessary components, is called a mortar mixture. The mortar mixture may consist of dry components mixed at the factory. This is the so-called dry mortar mixture. It is closed with water before use.

hardened mass resembling fake diamond, in which the binder binds sand particles together, thereby reducing friction, is called a solution.

Mortars are classified in the following way.

Depending on the binder used in the composition, there are:

1.Simple one-component- cement, lime or gypsum. As a rule, they are indicated by the ratio 1:2, 1:3, in which 1 is a part (share) of the binder, the second number is how many parts of the aggregate are added to the part of the binder.

2. Complex, mixed, multicomponent. These are, for example, cement and limestone, limestone and gypsum, clay and straw, limestone and ash, and others. They are designated by three numbers: basic binder, additional binder, filler.

A lot also depends on the quantitative ratio of binder and sand. There are building solutions:

1. Normal. They are characterized by an optimal ratio of binder and filler.

2. fatty. They are characterized by an excess of binder, give a large shrinkage during laying, cracks (when applied in a thick layer). They are determined by immersing the stick in a solution - the fatty mixture envelops it with a thick layer.

3. Skinny. They are characterized by a disadvantage, a small amount of binder, practically do not shrink, are optimal for facing. They are defined as follows: when the stick is immersed in the solution, the mixture does not stick to it.

According to the properties of the binder, building mortars are divided into:

Air - their hardening occurs in air in dry conditions (gypsum);

Hydraulic - hardening processes begin in air and continue in a humid environment, for example, in water (cement).

Depending on the sand used, whether it is ordinary natural, mountain, river or light porous (expanded clay, pumice, tuff), there are heavy (dry density from 1500 kg / m3) and light (up to 1500 kg / m3) mortars. The quality of the aggregate directly affects the strength of the final product. So, in comparison with slag, mixing the binder with building sand without impurities (mineral salts, inclusions of clay rocks) increases the strength of the solution up to 40%.

The quantitative ratio of water also plays an important role in the preparation of solutions: with a lack of it, the solution is characterized by rigidity, with an excess - delamination, as a result of which quality characteristics strength is reduced.

Confirmation that the mortar (GOST 28013-98) is prepared correctly, according to quality standards and the correct ratio of the required components, is its workability. The mobile, plastic composition is able to fill all the voids, it is well compacted, rammed, does not crumble, does not crumble, does not slip along the walls. With a slight addition of a binder and a mortar, the solution becomes more plastic, but this leads to greater shrinkage of the building material during hardening and, accordingly, to the formation of cracks.

Let's take a closer look at technical features mortar mixtures and solutions, all parameters of which are controlled by the current standards.

Qualitative characteristics of mortar mixtures

Important quality indicators of mortar mixtures are the average density, the ability to retain water, mobility and stratification. The lower the binder consumption for the requirements for mixtures, the better. If the mixture has had time to seize or it has thawed, it is strictly forbidden to add a sealer to it. To achieve the desired properties, it is important to properly prepare mortar mixtures, dose, and adjust the substances in them. These should be mixers of cyclic (continuous type), gravitational (forced) action. At the same time, an error of up to 2% is permissible with respect to binders, a mixing agent, dry additives, up to 2.5 - with respect to aggregate. For winter conditions, the solution temperature should be equal to or greater than 5 °C. Optimum temperature mixing water - up to 80 °C.

Depending on the rate of mobility, several grades of mortar mixtures are distinguished:

1. Pk4 - characterized by a mobility rate of 1-4 cm. It is used in vibrated

2. Pk8 - the fork of mobility variations is based in the range from 4 to 8 cm. It is relevant for ordinary rubble (from hollow stones and bricks) masonry, facing works, installation of walls (large-block, large-panel).

3. Pk12 - mobility over 8 and up to 12 cm. It is used when laying ordinary bricks, plastering, cladding, filling voids.

The ability of freshly prepared mortar mixtures to retain water is also one of the significant indicators. The quality indicator in laboratory conditions is 90% in winter, 95% in summer. At the place of production, it must exceed 75% of the water-holding capacity determined by laboratory data. How more density, the higher the waterproof rating. For factory dry mortar mixtures, moisture content up to 0.1% by weight is acceptable.

With regard to stratification and average density, then for both indicators an error is allowed within 10%, not higher. If air-entraining additives are added to the mortar mixture, relative to the average density, the indicator decreases to 6% of the one established by the project.

Quality standards for mortars

Average density, frost resistance, compressive strength are the main quality indicators of solutions. So, there are several grades that determine the axial compressive strength:

F10, F15, F25, F35, F50, F75, F100 - grades that characterize the frost resistance of the solution, which is subjected to alternate freezing and thawing. The frost resistance index has one of the paramount values ​​for concrete, masonry, plaster solutions when it comes to exterior plaster. All brands of solutions are controlled.

According to the density, building mortars (GOST 28013) are divided into heavy and light ones, the fork of deviations in indicators cannot be higher than 10% of that established by the project. The heaviest is the concrete mix. It is used when laying foundations, building basement floors. The higher the density, the stronger, harder the solution.

Quality standards for substances that make up solutions

As substances used for the preparation of mortars, cement, lime, gypsum raw materials, sand, including from slags from thermal power plants, are used. All these components, as well as water for mortars, must meet certain requirements, as given by GOST 28013, and quality standards for each component.

Aggregate

For each individual mortar, depending on the purpose, a specific filler of the required moisture content is needed. So, building sand with a grain size of up to 1.25 mm is suitable for finishing work, for soil - up to 2.5 mm, when plastering sand grains can reach 1-2 mm, when plastering the finishing layer - no more than 1.25 mm (possible deviations up to 0.5% by weight, but the solution should not contain sand with grains over 2.5 mm). If sand with ash is used, then the mass should not contain ice, frozen lumps. When heated, the temperature construction sand cannot exceed 60 °C. Light mortars involve mixing a binder with porous sand (shungite, vermiculite, expanded clay, perlite, slag pumice, aglonirite, fly ash, and others). Decorative mortars are made from washed crumbs of rocks with a grain size of up to 2.5 mm (granite, marble, ceramics, coal, plastic). Color plastering of facades involves the use of 2-5 mm granite, glass, ceramic, coal, slate, plastic chips. Color cement-sand plastering is carried out by adding colored cement, natural or artificial pigments of the corresponding standards to the composition of the solution.

Chemical additives

The preparation of mortars often involves the addition of various improving chemical additives to their composition, which prevent delamination, contribute to greater mobility, strength, and increase the frost resistance of the mixture. These are the so-called superplasticizing, plasticizing, stabilizing, water-retaining, air-entraining, accelerating hardening, retarding setting, antifreeze, sealing, water-repellent, bactericidal, gas-forming complexes. The last four are for use in special cases.

The required amount of chemical additives is determined by mixing in the laboratory. Produced in accordance with standards, they do not cause destruction of materials, corrosive effects on buildings and structures in use. Classified by type, brand, they all have symbols, as well as designations of standard and specifications. Thus, sodium sulfate (SN, GOST 6318, TU 38-10742) can be attributed to accelerating hardening additives, urea (urea) (M, GOST 2081) to antifreeze additives, carboxymethylcellulose (CMC, TU 6-05-386) to water-retaining additives. . A complete list of additives is specified in the appendix to GOST 28013. Cement mortar is produced with the addition of organic (microfoaming agents) and inorganic (clay, lime, cement dust, fly ash and others) plasticizers.

Technical quality control

An enterprise that manufactures mortar mixtures, in without fail technical control is carried out on the dosing of the necessary components and the preparation of the actual mortar mixture. Control is carried out once per shift. Mortar mixtures of the same composition, produced per shift, are delivered in batches. At the same time, the laboratory is sent control samples(selected according to GOST 5802) to determine all technical characteristics.

If the consumer specifies other than those specified in GOST 28013, it is subject to control by agreement between the manufacturer and the consumer.

Testing of mortars is carried out in laboratory conditions by the manufacturer, from which the consumer has the right to request control samples of the mortar mixture and solutions. The mortar mixture is dispensed by volume, the dry mortar mixture is dispensed by weight.

Regarding the characteristics of the mortar mixture for the ability to exfoliate and retain liquid, and the mortar for frost resistance, a check is carried out when selecting or changing the composition or characteristics of the mortar components. Further, the products are subject to inspection every six months. If, in the event of verification, non-compliance with the current standard is found, the entire batch is rejected.

What should be contained in the documents for the goods?

The documents serving as confirmation of product quality and endorsed by the representative of the manufacturer responsible for technical control must contain the following information:

Name and address of the manufacturer, exact date and the preparation time of the mixture;

brand of solution;

Type of binder;

Quantity, mobility of goods;

Name and quantity of chemical additives;

An indication of this standard, which is a guarantee of compliance of ready-to-use products with technical data.

If porous aggregates are used, the average density in the dried state is additionally recorded. For a dry mixture, the volume of the mixer is prescribed so that the mixture acquires the desired mobility. The documents must also contain guarantee period storage of the mixture in dry form, which is calculated from the date of preparation until the expiration of six months.

Transportation of mortar mixtures

When transporting mortar mixtures, it is important to exclude the loss of laitance. It is permissible to transport products by road, as well as in tubs (bunkers) by cars and on railway platforms. At the same time, the temperature of the transported mortar mixture should be checked, which is recorded when the technical thermometer is immersed to a depth of 5 cm.

In dry form, mortar mixtures are transported in cement trucks, containers or packaged up to 40 kg (paper packaging) and up to 8 kg (polyethylene packaging). At the same time, in paper bags, transportation is carried out on wooden pallets, in polyethylene - by placing bags with a mixture in special containers. Storage of the mixture in bags is allowed at a temperature of 5 ° C in closed dry rooms. After transportation, the mortar mixture is unloaded into a mixer or other containers.

The scope of building solutions is diverse. Construction concretes and mortars based on cement binder as structural material are widely popular both in private and industrial construction during the construction of strong load-bearing foundations, horizontal, vertical, inclined structures, structures, ceilings, during capital and current repair, reconstructions, restorations.

It is generally accepted that during the construction of stone buildings, the consumption of mortars reaches a quarter of the total volume of the structure. Many of us have ever purchased lime, gypsum, mixed building mortars for plastering walls in apartments or private households (these are the so-called finishing compounds). Also someone had to buy masonry mortars for installation work, cladding, masonry, refractory. On the construction market now you can find building mortars (GOST 28013), which have superior properties of thermal insulation, sound absorption, heat and fire resistance.

K category: The choice of building materials

Properties of solutions and mortar mixtures

For successful use in a particular area, solutions must have certain required properties: density, strength, frost resistance, water resistance, change in volume during hardening, and in some cases chemical resistance. Solutions with the required properties are obtained by selecting the composition of the mortar mixture. At the same time, the need to impart certain properties to the mortar mixture itself, dictated by the technology of work, is taken into account. The main properties of the mortar mixture are mobility, water-holding capacity and non-separability.

Properties of solutions. By density, solutions are divided into heavy and light. Heavy solutions include solutions with an average density of 1500 kg/m3 or more. They are prepared on dense aggregates with bulk density more than 1200 kg/m3. Light solutions are prepared on porous aggregates with a bulk density of less than 1200 kg/m3; the average density of such solutions is less than 1500 kg/m3.

Heavy solutions, as a rule, have greater strength, while light solutions have lower thermal conductivity due to the presence of air pores. But they are less frost-resistant, so they are used more often for plastering rooms or for floor preparation.

The strength of the solutions is characterized by the brand. The grade of the mortar is determined by the compressive strength of standard samples-cubes, which are made from the working mortar mixture and tested after 28 days of hardening at a temperature of 25 ° C in accordance with GOST 5802-78. In terms of compressive strength (kg / cm2), grades 4, 10, 25, 50, 75, 100, 150, 200 and 300 are installed for mortars. Mortars of grades 4 and 10 are made mainly on lime and local binders. Tensile strength of mortars in 5. . .10 times their compressive strength.

The strength of mortars is affected by: the activity of the binder, the quality of aggregates, the amount of water, the conditions of preparation and hardening, the hardening time.

The binder present in the mortar mixture in the form of an astringent dough hardens to form a dense stone that connects the aggregate particles. Therefore, the strength of the mortar will be determined both by the strength of the hardened dough of the binder and by the strength of its adhesion to the aggregate.

The strength of the hardened binder depends on its activity (brand) and the compliance of the conditions for the hardening of the solution optimal conditions binder hardening. So, for successful hardening of cement mortars, it is necessary to maintain the humidity of the solution long time- up to several weeks, since the increase in its strength occurs gradually, however, the rate of increase in strength decreases with time (Fig. 1). Gypsum mortars set quickly and require dry curing conditions. Lime mortars harden slowly, require dry curing conditions and have low strength.

Most mortars used in finishing work should have a relatively low grade of 25 ... lime (or clay).

Rice. 1. Graph of the increase in compressive strength of a cement slurry hardening under normal conditions

The strength of the mortar is largely dependent on the strength of the aggregate. Thus, the strength of a mortar with a filler of strong rocks can be 25 ... 50% higher than when using fillers with low strength (slag and other porous fillers).

The irregular shape and rough surface of the aggregate provide better adhesion to the hardening binder. Solutions on such fillers, other things being equal, have a higher strength than with fillers with a rounded shape and a rounded grain surface.
The presence of foreign impurities (eg, clay) in the aggregate, as a rule, reduces the adhesion of aggregates to the binder and reduces the strength of the solution. In some cases, impurities cause a change in the volume of the solidified solution. Thus, the swelling of clay particles when wetted with water leads to the formation of cracks in the solution. Sodium or calcium sulfate impurities in the aggregate destroy the cement stone.

The amount of mixing water also affects the strength and other properties of the solution. It is customary to characterize it with a water-binding ratio, that is, a number that is obtained by dividing the mass of mixing water by the mass of binders. Depending on the type of binder material, water-cement, water-lime ratio, etc. are distinguished.

It has been established that with an increase in the water-binding ratio above a certain limit, the strength of the solution decreases. However, when preparing mortars, more water is taken than is required to ensure chemical reaction binder hardening.

Usually the water-binding ratio is close to 0.5, although it is sufficient for the cement to be completely hydrated if the water-cement ratio is about 0.2.

The need to increase the amount of water in the mortar mixture is caused by the following: it is very difficult to work with a mortar mixture containing a small amount of water, since it is very hard; excess water in the mortar mixture must compensate for its loss from evaporation from the outer surface and from the absorption of water by the base materials on which the mortar is applied.

In order for the solution to be strong, all its components must be well mixed, and the mixture must be homogeneous. Specifications establish the minimum period for mixing the mortar mixture in the mortar mixer. Hardening conditions also affect the strength of the solution. Lowering the temperature slows down the hardening reaction of the binder, and freezing the solution at an early stage of hardening leads to a sharp decrease in its strength due to a violation of the structure of the hardening binder, which has not yet gained sufficient strength. The rapid evaporation of water when drying the solution with heating devices or in hot climates can lead to the fact that in the surface layer it will not be enough to hydrate the binder and such a solution will crumble. To prevent this from happening, the surface of the solution must be wetted.

The water resistance of the solution is great importance in structures such as outdoor plaster buildings, plaster or underlay for ceramic tiles in the bathroom, special waterproofing plasters for industrial buildings. There are no absolutely waterproof solutions and it is considered to be waterproof a solution that allows a certain amount of water to pass through, which completely evaporates from its surface, leaving no wet spots. Dense solutions pass through water least of all, i.e., with a high average density.

Water resistance can be increased by adding water-repellent (ceresite, bitumen, synthetic resins) or sealing ( liquid glass) additives.

The frost resistance of the solution is more dependent. on its density and water resistance. The larger they are, the more frost-resistant the solution. The requirements for frost resistance must be met by mortars for external plasters and underlying layers for external cladding. For building mortars, frost resistance grades Mrz 10 ... 300 are established.

The hardening of most binders is accompanied by a change in volume. So, gypsum binders increase their volume, lime binders and most cements decrease. The exception is special expanding and non-shrinking cements.

The decrease in the volume of the solution, caused by a change in the volume of the hardening binder, is called the shrinkage of the solution. Shrinkage, in addition to the type of binder material, depends on the ratio of the amount of binder and aggregate, the water-binding ratio, and on the time and conditions of the mortar hardening.

The shrinkage of the solution increases with an increase in the amount of binder per unit volume of the solution, as well as with an increase in the water-binding ratio. The shrinkage deformations increase especially rapidly in the initial stage of mortar hardening, then their growth gradually decreases and dies out. In cement mortars, shrinkage practically stops after 90–100 days. Absolute shrinkage varies considerably: for conventional solutions, it is 0.1 ... 0.4 mm / m; in extreme cases, it can reach several millimeters per 1 m of length.

In plastering, facing and mosaic;; In works, shrinkage is an undesirable phenomenon, since shrinkage deformations cause stresses between the mortar layer and the base or lining, which can lead to cracks and destruction of the mortar. To reduce shrinkage, solutions are prepared with a minimum necessary quantity binder material, various additives are also used.

Properties of mortar mixtures. The mobility of a mortar mixture characterizes its ability to spread under the action of its own weight or external forces applied to it.

Rice. 2. Device for determining the mobility of mortar (a) and mosaic (b) mixtures: 1 - solution vessel, 2 - reference cone, 3 - starting screw, 4 - scale, 5 - sliding rod, 6 - holders, 7 - tripod, 8 - truncated metal cone, 9 - handles, 10 - paws

To determine the mobility of the mortar mixture, a device is used (Fig. 2, a), consisting of a tripod with holders attached to it, in which the rod can slide. A reference cone with a height of 180 mm and a base diameter of 150 mm, weighing (300 + 2) g is attached to the lower end of the rod. For testing, the solution is mixed, the vessel is filled with it about 1 cm below its edges. The solution is compacted by bayoneting 25 times with a steel rod with a diameter of 10 ... 12 mm, and the vessel is shaken 5 ... 6 times by light tapping on the table. The device is installed on horizontal surface(table) and check the freedom of sliding of the cone rod in the holders. The rod with the cone is raised to the upper position, fixed with a starting screw, and the vessel with the solution is mounted on a tripod. Lowering the starting screw, bring the tip of the cone of contact with the solution, fix the rod with a screw and record the reading on the scale. Then the screw is released, allowing the cone to freely sink into the solution, and at the end of the cone's immersion, the second reading is recorded on the scale. The difference in centimeters between the second and first readings gives the depth of the cone.

The mobility of mosaic and concrete mixtures is determined using a cone shape (Fig. 2, b) 300 mm high, with the inner diameters of the lower - 200 mm, the upper - 100 mm. The cone shape is loaded with the test mixture and sealed with a bayonet (GOST 10181.1-81). After that, the cone shape is removed and the difference between the height of the cone shape and the mosaic or concrete mixture is measured. The value of this value (cm) serves as an indicator of mobility.

The mobility of the mixture depends on its composition: primarily on the amount of water and binder, as well as on the type of binder and the ratio between binder and aggregate. Other things being equal, fatty mortar mixtures are more mobile than lean ones. Lime and clay give more mobile mixtures than cements.
The type of binder material and the composition of the solution are usually set depending on the required strength of the solution and the operating conditions of the corresponding surfaces of the building or room. The mobility of the mortar mixture is regulated by reducing or increasing the amount of binder and mixing water. By increasing the amount of water and binder in the mortar mixture, more plastic, workable mortar mixtures are obtained, but at the same time, the shrinkage of the solution increases.

When adding water to the mortar mixture and a constant amount of binder, the mobility of the mixture increases, but the strength of the solution decreases, and its porosity increases. Therefore, with an increase in the amount of water, the consumption of the binder should be proportionally increased.

In some cases, it is not advisable to increase the consumption of an expensive binder, such as cement, but it is possible to improve the mobility of the mixture by adding a cheaper binder, such as lime or clay. In this case, the second binder will play the role of an inorganic plasticizer. In those cement mortars where the addition of lime and clay is not allowed, organic plasticizers are used - surfactants, such as sulfite yeast mash (SDB).

Water holding capacity characterizes the ability of a mortar mixture to hold water. This property is of great importance when applying the mortar mixture on porous substrates, as well as during its transportation. If a mortar mixture with a low water-retaining capacity is applied, for example, to brick or cinder-concrete masonry, then it quickly dehydrates. This will happen because the fine pores of the base have the ability to suck in water and, together with it, particles of the binder. The solution in this case is less dense and much less durable. To compensate for the loss of water, the applied solution has to be moistened periodically for several days.

The water-retaining capacity of the mortar mixture is usually characterized by a change in the mobility of the solution after the suction of water from it through a filter funnel at a rarefaction of 6.65 kPa for 1 min.
The water-retaining capacity of the solution depends on the ratio of water and binder and on the amount of binder in the solution. When the solution contains a sufficient amount of binder, water, forming adsorption shells on the developed surface of finely dispersed particles of the binder, is firmly held on them. good example this is clay dough, from which it is extremely difficult to remove water.

Delamination is observed when transporting the mortar mixture by motor vehicles or through pipelines using mortar pumps. In this case, the mixture is divided into solid and liquid phases: the solid phase - sand and binder are deposited, the liquid - water is collected at the top. In the pipeline, such a mixture forms plugs, the elimination of which is associated with large losses of working time.

You can check the solution for stratification as follows. The solution is placed in a bucket with a layer about 30 cm high and the depth of immersion of the reference cone is determined. After 30 minutes, the upper part of the solution (about 20 cm) is removed and the depth of immersion of the cone is determined for the second time. The difference in cone immersion values ​​for non-stratified solutions is close to zero, with an average stratified one being within 2 cm. A discrepancy in readings of more than 2 cm indicates that the solution is highly stratified.

To prevent delamination of mortar mixtures, it is necessary to correctly select their composition. If the ratio of filler and binder in the solution is chosen correctly, then the binder dough fills all the voids between the filler grains and envelops each of its particles with a uniform layer; such a mortar mixture, having a water-retaining capacity, does not delaminate. Plasticizing additives also increase the water-retaining capacity of mortar mixtures and reduce their stratification.

STATE STANDARD OF THE UNION OF THE SSR

BUILDING SOLUTIONS
GENERAL SPECIFICATIONS

GOST 28013-89

USSR STATE CONSTRUCTION COMMITTEE

Moscow

STATE STANDARD OF THE UNION OF THE SSR

Introduction date 01.07.89

This standard applies to mortars used for masonry, installation building structures, facing and plastering works under various operating conditions.

This standard does not apply to heat-resistant, chemically resistant and straining mortars.

The standard establishes technical requirements for building mortars and materials for their preparation, as well as rules for the acceptance and control of mortar quality indicators and transportation rules.

1. TECHNICAL REQUIREMENTS

1.1. Construction solutions () must be prepared in accordance with the requirements of this standard according to the technological documentation approved in the prescribed manner.

1.2. Building mortars are divided according to the type of binder into simple ones using one type of binder (cement, lime, gypsum and others) and complex using mixed binders (cement-lime, lime-ash, lime-gypsum, etc.).

1.3. Characteristics of mortar mixtures

1.3.1. The main indicators of the quality of the mortar mixture () are:

mobility;

water holding capacity;

stratification;

average density.

1.3.2. Depending on the mobility, mortar mixtures are divided into grades in accordance with.

1.3.3. The water-retaining capacity of a freshly prepared mortar mixture, determined in laboratory conditions, must be at least:

90% - for mortar mixtures prepared in winter conditions;

95% - for mortar mixtures prepared in summer conditions.

The water-holding capacity of the mortar mixture, determined at the place of work, must be at least 75% of the water-holding capacity established in the laboratory.

1.3.4. The stratification of a freshly prepared mortar mixture should be no more than 10%.

1.3.5. The deviation of the average density of the mortar mixture upwards is allowed no more than 10% of the one established by the project. When using air-entraining additives, the decrease in density should not exceed 6%.

1.3.6. The compositions of mortar mixtures should be selected in such a way as to ensure that mortar mixtures with desired properties are obtained at the lowest flow binder.

1.3.7. It is forbidden to add water (with or without cement) to the set mortar mixtures, including to warmed with hot water, frozen mixtures during work in winter conditions.

1.3.8. Dry mortar mixtures () manufactured at the factory must be with a moisture content of not more than 0.1% by weight.

1.3.9. In dry plaster plaster mixes(OGSHS) it is necessary to introduce complex additives, given in, to slow down the setting time and plasticization of the mortar mixture.

1.3.10. When preparing mortar mixtures, dosing of binders and aggregates should be done by weight, and water and additives in liquid form - by weight or volume and adjusted when the properties that make up the mortar mixture of materials change. Porous aggregates are allowed to be dosed by volume with correction by weight. Dosing error should not exceed:

± 2% - for binders, water, dry additives, working solution of liquid additives;

± 2.5% - for aggregate.

Dosing devices must meet the requirements of GOST 10223. The temperature of the solutions used in winter period, must be at least 5 ° C. Water for mixing solutions should have a temperature of no more than 80 ° FROM.

1.3.11. Mortar mixtures should be prepared in mixers of a cyclic or continuous type, gravity or forced action.

1.4. Solution characteristics

1.4.1. The main indicators of the quality of the solution () are:

compressive strength;

frost resistance;

average density.

1.4.2. Depending on the operating conditions of the structure of buildings and structures, it is allowed to establish additional requirements for mortar quality indicators provided for by the GOST 4.233 nomenclature.

1.4.3. The strength of the solution is characterized by grades for axial compressive strength at the age of 28 days. The strength grade of the solution for axial compression is assigned and controlled in all cases.

For the solution, the following grades for compressive strength are established: M4; M10; M25; M50; M75; M100; M150; M200.

1.4.4. For a solution subjected to alternate freezing and thawing, in a moist state in the structures of buildings and structures, frost resistance grades are assigned and controlled: F10; F15; F25; F 35; F50; F75; F 100.

Solutions must meet the requirements for frost resistance established by the standard.

1.4.5. According to the average density, the solutions are divided into:

heavy (with an average density of 1500 kg / m 3 or more);

light (with an average density of less than 1500 kg / m 3).

The normalized value of the average density of the solutions is set by the consumer in accordance with the work project. The deviation of the average density of the solution is allowed no more than 10% of the one established by the project.

1.5. Requirements for materials for the preparation of mortars

1.5.1. Materials used for the preparation of mortar mixtures must meet the technical requirements of this standard and comply with the requirements of standards or specifications for these materials.

1.5.2. Cement for the preparation of mortar mixtures must meet the requirements of GOST 25328 or GOST 10178, lime - GOST 9179, gypsum - GOST 125, sand - GOST 8736, sand from slags of thermal power plants - GOST 26644, fly ash - GOST 25818, hydraulic ash - TU 34 -31-16502, water for mixing mortar mixtures and preparing additives - GOST 23732, blast-furnace slag - GOST 3476.

1.5.3. Depending on the type and purpose of mortars, various types of aggregates should be used.

1.5.4. The moisture content of the aggregates and the temperature of the mixture (if necessary) are determined during the selection and adjustment of the composition.

1.5.5. As a filler in plaster mortars, sand for construction work with a fineness modulus of 1 to 2 should be used. Sand with a grain size of no more than 2.5 mm should be used in solutions for spraying and soil, and for the finishing layer - no more than 1.25 mm .

1.5.6. Sand and ash used to prepare the solution should not contain frozen clods larger than 1 cm, as well as ice. When heating sand, its temperature should not exceed 60 ° FROM.

1.5.7. For light mortars, porous expanded sands (vermiculite, perlite, expanded clay, shungizite, from slag pumice, agglonirite according to GOST 19345, fly ash according to GOST 25818, ash component of ash from hydraulic removal of ash and slag mixture according to TU 34-31-16502 should be used as a filler.

1.5.8. Various aggregates can be used for decorative mortars, for example, washed quartz sands and crumbs of crushed rocks (granite, marble, ceramic, coal, plastic) with a grain size of not more than 2.5 mm.

For colored plasters used on facades, in interiors, it is allowed to use granite, glass, ceramic, coal, slate, plastic chips with a particle size of 2-5 mm.

1.5.9. For the preparation of colored cement-sand plaster mortars, colored cements should be used according to GOST 15825, natural or artificial pigments according to GOST 8135, GOST 18172, GOST 12966.

1.5.10. To obtain mobile and non-separable mortar mixtures, as well as to accelerate the growth of mortar strength, increase frost resistance, etc., various types of additives (plasticizing, air-entraining, accelerating and slowing down setting and hardening, antifreeze, etc.) and complexes on their basis in accordance with GOST 24211 and applications,.

The choice of chemical additives should be made depending on the required design characteristics of the mortar mix.

Chemical additives should not cause harmful effects during the operation of buildings (destruction of materials, corrosion of reinforcement, efflorescence, etc.).

It is allowed to use inorganic plasticizing additives in cement mortars (clay, lime, cement dust captured during the production of clinker, carbide sludge, fly ash and hydraulic ash from thermal power plants, ash and slag mixtures, sludge from treatment facilities of metallurgical industries) and organic plasticizers-microfoamers that meet the requirements of the relevant material standards. The amount of additive is determined by experimental batches in laboratories.

2. ACCEPTANCE

2.1. Mortar mixtures must be taken technical control manufacturer.

2.2. Dosing and preparation of the mortar mixture should be controlled once per shift.

2.3. Mortar mixtures are taken in batches. A batch is taken as the amount of a mortar mixture of the same composition, prepared during one shift.

2.4. The manufacturer is obliged to report the test results of control samples of the solution to the consumer at his request.

The consumer has the right to carry out a control check of the quality of the mortar mixture and mortar in accordance with the requirements of this standard.

2.5. The release of the mortar mixture by the manufacturer and its acceptance by the consumer is carried out by volume, and the dry mortar mixture - by weight.

2.6. Mortar mixture released into vehicle, the manufacturer must accompany with a quality document indicating:

name and address of the manufacturer;

date and time (hours, minutes) of mixture production;

brand of solution;

type of binder;

the amount of the mixture;

the mobility of the mixture;

name and quantity of additives;

designation of this standard.

In the quality document for a batch of mortar mixture on porous aggregates, it is additionally necessary to indicate average density solution in the hardened dried state.

The quality document must be signed by the manufacturer's representative responsible for technical control.

When supplying a solution in the form of a dry mixture, indicate the amount of water required to mix the mixture to the required mobility.

2.7. The mortar mixture for water-holding capacity and stratification, and the mortar for frost resistance are evaluated when selecting each composition of the mortar, and then at least once every 6 months, as well as when changing the composition of the mortar or the characteristics of the materials used.

2.8. If, when checking the quality of the mortar, it turns out that it does not meet at least one of the technical requirements of the standard, the batch of mortar is rejected.

2.9. From each batch of the mortar mixture, the laboratory of the manufacturer must take control samples to determine the mobility and average density of the mortar mixture, compressive strength and average density of the mortar according to GOST 5802.

2.10. Dosing and preparation of the mortar mixture should be controlled once per shift.

3. CONTROL METHODS

3.1. Mobility, average density, stratification, water-retaining capacity of the mortar mixture, as well as compressive strength, average density and frost resistance of the mortar are controlled according to GOST 5802.

3.2. The quality of the mortar mixture and solution according to the indicators specified in technical requirements consumer and not specified in paragraphs. and , control by agreement between the manufacturer and the consumer.

3.3. Mortar samples should be taken according to GOST 5802.

3.4. Dosers should be checked in accordance with GOST 8.469, GOST 8.523.

3.5. The temperature of the transported mortar mixture is measured with a technical thermometer according to GOST 2823, immersing it in the mixture to a depth of at least 5 cm.

4. TRANSPORT AND STORAGE

4.1. Mortar mixtures must be delivered to the consumer in vehicles that exclude the loss of cement laitance. It is allowed to transport the mortar mixture in bunkers (buckets) on motor vehicles and railway platforms.

4.2. Dry mortar mixtures should be delivered to the consumer in cement trucks, containers or special bags: paper weighing up to 40 kg, polyethylene weighing up to 8 kg, protecting the mixture from moisture. Packed in bags, dry mixes are placed on wooden pallets, and plastic bags- in special containers.

Bags with dry mix should be stored in dry closed rooms at a temperature not lower than 5 ° FROM.

4.43. The mortar mixture delivered to the construction site must be unloaded into a loader-mixer. Unloading into other containers is allowed, provided that the specified properties of the mortar mixture are preserved.

5. MANUFACTURER WARRANTY

5.1. The manufacturer shall ensure that the ready-to-use mortar mix, including dry mix, complies with the requirements of this standard.

5.2. Guaranteed shelf life of dry mortar mixtures - 6 months. from the day they were prepared.

ATTACHMENT 1
Reference

TERMS USED IN THIS STANDARD AND THEIR EXPLANATIONS

Mortar combines the concepts of mortar mixture, dry mortar mixture, solution.

Mortar mixture - it is a mixture of binder, fine aggregate, tackifier and necessary additives, thoroughly mixed, ready for use.

Dry mortar is a mixture of dry components of a binder, aggregate and additives, dosed and mixed at the factory, mixed with water before use.

Solution- this is an artificial stone-like material, which is a hardened mixture of binder, fine aggregate, caulk and necessary additives.

APPENDIX 2
Mandatory

Mortar grades by mobility

APPENDIX 3
Reference

APPENDIX 4
Reference

Modified technical lignosulfonates recommended for mortars

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the State Construction Committee of the USSR

PERFORMERS

G.N. Brusentsov,cand. tech. sciences (topic leader); I.A. Spasskaya, cand. Phys.-Math. sciences; G.M. Kirpichenkov, cand. tech. sciences; E.B. Madorsky, cand. tech. sciences; S.A. Vorobiev, cand. tech. sciences; G.A. Zakharchenko, cand. tech. sciences; G.M. battery, cand. tech. sciences; M.I. Brusser, cand. tech. sciences; THEM. Drobyashchenko, cand. tech. sciences; V.R. Falikman, cand. chem. Sciences, DI. Prokofiev, M.I. Shimanskaya

2. APPROVED AND INTRODUCED BY Decree of the State Construction Committee of the USSR dated 13.01.89 No. 7

3. INTRODUCED FOR THE FIRST TIME

4. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS

The mobility of the mortar mixture is its ability to spread under the action of its own mass or external forces applied to it (GOST 5802-86). It is characterized by the depth of immersion of a standard cone for a certain period.

The scheme of the device for determining the mobility is shown in fig. 13; a steel rod with a diameter of 12 mm and a length of 300 mm is used.

The reference cone of the device is made of sheet steel or plastic with a steel tip. Reference cone parameters; weight with a barbell - 300 ± 2 g; height - 145 mm; base diameter - 75 mm; apex angle - 30° ±30".

For the mortar mixture, a vessel with a capacity of 3 liters is used, the diameter of its lower base is 150 mm, the diameter of the upper base is 250 mm, and the height is 180 mm.

The device is placed on a horizontal surface and the sliding of the rod 6 in the guides 5 is checked.

The mortar mixture is filled into vessel 2 mounted on a tripod. In this case, the level of the mixture should be 10 mm below the edges of the vessel. Then, the mortar mixture is compacted by baying with a steel rod 25 times, followed by repeated light tapping of the vessel on the table. The mortar mixture prepared in this way is ready for testing.

The tip of the standard cone 3 is brought into contact with the surface mortar mixture in the vessel, the rod of the standard cone is fixed with a locking screw 4 and the first reading is made on the scale. Then the locking screw is released. 1 min after the free immersion of the standard cone, a second reading is made on the scale with an error of up to 1 mm.

The mobility of the mortar mixture is estimated in centimeters as a space between the first and second readings.

The result is taken as the arithmetic mean of the results of two yen tany on different samples of the mortar mixture of one batch.

The stratification of the mortar mixture is determined (GOST 5802-86), comparing the mass content of the aggregate in the lower and upper parts freshly molded compacted sample. The definition sequence is as follows. A mortar mixture is placed in metal molds with dimensions of 150x150x150 mm, then the filled molds are placed on a laboratory vibration platform of type 435A and the mixture is subjected to vibration for 1 min. After vibrating is completed, the upper layer of the mortar mixture with a height of 7.5 ± 0.5 mm is taken from the mold and placed in a baking sheet, and the lower layer is unloaded into the second baking sheet by overturning the mold. The upper and lower layers are weighed with an error of up to 2 g and wet sieving is carried out on a sieve with a hole diameter of 0.14 mm. Rinse with a stream of clean water until the binder is completely removed (from the sieve pure water). Washed filler top and lower parts placed on a clean baking sheet, dried at a temperature of 105-110 ° C to constant weight and weighed with an error of up to 2 g.

The test result is taken as the arithmetic mean of the results of two determinations that differ from each other by no more than 20% from the smaller value.

The water-retaining capacity is estimated by the weight loss of a 12 mm thick layer of mortar laid on 10 sheets of blotting paper (GOST 5802-86). The scheme of the device is shown in fig. fourteen.

The test procedure is as follows. 10 sheets of blotting paper measuring 150x150 mm are weighed with an error of up to 0.1 g, then they are placed on a glass plate measuring 150x150 mm, a gauze pad is placed on top and a metal ring with an inner diameter of 100 mm, a height of 12 mm and a wall thickness of 5 is placed on top mm and weigh again.

The mortar mixture, previously thoroughly mixed, is placed in a metal ring flush with the edges and weighed. After 10 minutes, the ring with the solution and gauze is carefully removed. The blotting paper is weighed to the nearest 0.1 g.

The test result is taken as the arithmetic mean of the results of two determinations that differ from each other by no more than 20% from the smaller value.

The density of the mortar mixture is characterized by the ratio of the mass of the compacted mortar mixture to its volume. Determination of density (GOST 5802-86) is carried out in the following sequence. A 1000 ml metal vessel is preliminarily weighed and filled with an excess of the mortar mixture. Then the mixture is compacted by baying with a steel rod 25 times and lightly tapping on the table 5-6 times.

The excess mortar mixture after compaction is removed and the surface is leveled with a metal ruler to the level of the edges of the vessel. The outer walls of the vessel are cleaned of the solution that has fallen on them. After that, the vessel with the mortar mixture is weighed with an error of up to 2 g. The density of the compacted mortar mixture, kg/m3, is calculated by the formula

The test result is taken as the arithmetic mean of the results of two tests that differ by no more than 5% from the lower value.

The setting time (GOST 310.3-76) is determined using the Vicat device. After mixing with water, the mortar mixture, losing plasticity and mobility, gradually thickens, which corresponds to the beginning of setting, and then turns into a stone-like body - the end of setting comes.

The beginning and end of the setting of the mortar mixture is determined in the following order. The freshly prepared mortar mixture is placed in the ring of the Vicat device with the following dimensions: lower diameter - 75 mm, upper diameter - 65 mm, height - 40 mm. A needle with a diameter of 1.1 mm and an inn of 50 mm is installed in the rod of the device.

The needle of the device is brought to contact with the surface of the mortar mixture, and in this position the rod is fixed with a clamping screw. Then the rod is released, after which the needle is freely immersed in the dough. The needle is immersed in the mortar mixture every 10 minutes. After each dive, the lead should not fall into the same place.

The beginning of setting is characterized by the time elapsed from the beginning of mixing until the moment when the needle does not reach the plate by 1-2 mm.

The end of setting is estimated by the time from the beginning of mixing to the moment when the needle is lowered into the mortar mixture by no more than 1-2 mm.

The suitability of the mixture should be checked before use. A bowl with a capacity of 200 cm3 filled with a freshly prepared thoroughly mixed mortar mixture is placed in a tightly closed container and kept at a temperature of 20 ± 2 ° C for the time specified in normative document. After that, the bowl with the mortar mixture is removed from the container. A suitable mortar mix should be easy to apply with a spatula without curling under it.

Drainage of putty from a vertical surface. The mortar mixture is applied with a layer of 2-3 mm on a concrete plate, set it in vertical position and kept at a temperature of 20 ± 2 °C for 30 minutes. Mortar mix should not flow down from a vertical surface.

The relative viscosity of mortar mixtures (GOST 8420-74) is determined on a VZ-246 picometer with a nozzle diameter of 4 mm and a capacity of 100 ± 1 cm3. The optimal expiration time range is from 20 to 200 s. The test is carried out at a temperature of 20 ± 2 °C in the following sequence. The viscometer is set to a vertical position using a level, a vessel with a capacity of 150 cm3 is placed under the nozzle. The opening of the viscometer nozzle is closed with a finger, the test material is slowly poured into the viscometer in excess to prevent the formation of bubbles. Excess material is removed with a glass plate. Then the nozzle opening is opened and, simultaneously with the appearance of the material from the nozzle, the stopwatch is started, stopping it at the moment of the first interruption of the jet of the test material. Count the expiration time.

The test result is taken as the arithmetic mean of the results of at least three measurements. Permissible deviations of individual determinations of the expiration time from the arithmetic mean value should not exceed ± 5%.

The viability of the mortar mixture (GOST 19270-73) is characterized by a change in the mobility of the mixture over a given time. To determine it, a drop of the mixture is transferred with a glass rod to the horizontal surface of a glass plate with dimensions of 300 * 250 mm. The plate is placed in a vertical position and fixed. Then measure the length of the drip in centimeters with a metal ruler. The plate with the mixture is placed in a desiccator and stored for the time specified in the regulatory document. After that, the plate is removed from the desiccator and the length of the drip is measured.

Hiding power characterizes the ability of the material, when applied to a black and white substrate, to reduce the contrast until the difference between black and white surfaces disappears (GOST 8784-75). The black and white background consists of squares drawn in black ink on the drawing white paper in a checkerboard pattern. On a sheet of paper 90x120 mm, 12 black and white squares of 30x30 mm are obtained. A 90 x 120 mm glass plate, preliminarily weighed, is placed on said substrate, and then paint is applied to the plate in layers until the difference between black and white squares completely disappears. After complete covering, the colored glass plate is weighed with an error of up to 0.02 g.

Covering power, g/m2, is calculated by the formula

The test result is taken as the arithmetic mean of the results of the two determinations.

Drying time of the paint to degree 3 (GOST 19007-73). The degree of drying characterizes the state of the surface of the material deposited on the plate, at a certain time and temperature of drying. Drying time - the period of time during which the specified degree of drying of the material is achieved at a certain thickness and drying conditions. To determine the drying time to degree 3, the mortar mixture is applied to concrete plates with dimensions of 50x50x25 mm. The surface of the plate is abundantly moistened with water. After the disappearance of the “water mirror”, the mortar mixture is applied to the surface of the plates with a brush or roller. The layer thickness is 140-150 microns. Test temperature 20 ±2 °C, relative air humidity 65 + 5%. Drying time is indicated in the regulatory documentation. When testing, a piece of paper is placed on a painted plate with tweezers. A rubber plate is placed on it, in the middle of which a weight of 200 g is placed. The degree of nmdrying is assessed 30 s after the load is removed.

If the paper does not adhere to the surface of the dried material, a dryness level of 3 is recorded.

The open hold time of the adhesive is determined by the time during which it is possible to stick the tile on the already applied adhesive layer.

The surface of the concrete slab is abundantly moistened with water. After the disappearance of the “water mirror”, glue is applied to the surface of the plate and leveled with a spatula, the layer thickness should be at least 0.5 mm. Ceramic tiles are laid on the adhesive layer with an interval of 5 minutes. Immediately after laying, each tile is loaded with a load of 3 kg for 30 s. After 40 minutes, all tiles are removed from the concrete slab and turned upside down with the glued strap up. The degree of filling with glue of the glued surface of the tile is determined as a percentage. open time adhesive hold time is the time in minutes at which 50% or more of the adhesive remains on the tile.

The resistance of the tile to displacement is determined by the displacement of the tile 30 minutes after the removal of the load from it. The mortar mixture is applied with a spatula to a horizontally located concrete tiles(base) with a diameter of 200 * 350 * 5 mm with a layer specified in the regulatory documentation. After 10 minutes, two ceramic tiles with dimensions of 150 * 150 * 5 mm are glued onto a concrete tile with a mortar mixture, in the middle of which they are placed on 30 with weights weighing 5 kg and the position is clearly marked ceramic tiles regarding the base. After 30 seconds, the weights are removed and the concrete slab with the cuts is placed in a vertical position. After 30 minutes, measure the distance over which the tiles are displaced.

The test result is taken as the arithmetic mean of the results of two tests with an error of up to ± 0.25 mm.

Spreadability is determined by the diameter of the spread of the mortar mixture. A metal cylinder with a diameter of 50.8 mm, a height of 45 mm and a wall thickness of mm, placed in the center of a glass plate with dimensions of 250 * 350 * 5 mm, is made with a mortar mixture, the excess of which is cut off with a ruler. The cylinder and glass are pre-wiped with a cloth. After 45 seconds, the cylinder is very quickly raised vertically by 15-20 cm and taken to the side.

The diameter of the spread is measured 2 minutes after the lifting of the Lipetsk cylinder in two perpendicular directions with an error of not more than 5 mm, and the arithmetic mean of the results of two measurements is calculated.

The allowable time for correcting the position of a tile is the time during which it is possible to change the position of a tile glued to a concrete surface. To define it for concrete slab apply a layer of glue with a thickness of at least 0.5 mm. Five tiles are laid on this layer. Weights weighing 1 kg are placed on the laid tiles and kept for 30 s. After 10 minutes, and then with an interval of 5 minutes, the next tile is corrected by turning it 90 ° and back to its original position. The prepared samples are left to harden for 28 days at a temperature of 20 ± 2 °C. After 28 days, the force of separation of the tile from the concrete base is determined.

Adhesion strength of tiles concrete base, which is not less than 0.5 MPa, corresponds to the allowable correction time, which is indicated in the regulatory documentation.