Classification of mortar mixtures and mortars, quality indicators. Properties of mortar mixtures and hardened solutions

Question.

12 workability, stratification, density, water retention.

14 .The mobility of the mortar mixture is called its ability to spread under the action of its own weight or applied to it external forces. The mortar mixture, depending on the composition, may have a different consistency - from rigid to cast. The degree of mobility of the mortar mixture is determined by the depth of immersion in the mixture of a metal cone (StroyTsNIL cone) (63) weighing 300 g, 145 mm high, base diameter 75 mm with an apex angle of 30°. The amount of mobility mortar mixtures in cm is characterized by the immersion of the cone in the solution. Mortars for masonry, building finishing and other works are made quite mobile: the mobility of mortars for brickwork equal to 9-13 cm, solutions for rubble masonry 1-3 cm, and others 4-6 cm.

The mobility of the mortar mixture is directly dependent on the content of water in it, however, it should not exceed a certain limit, above which the mortar mixture separates. This limit is determined by the cement-water ratio, and in mixed solutions - by the cement-binder ratio, that is, the ratio of the weight of the binder to the weight of water, and the weight of the cement with the additive is taken as the weight of the binder.

17 . DETERMINATION OF THE WATER-RETAINING CAPABILITY OF A MORTAR MIXTURE

The water-holding capacity is determined by testing a 12 mm thick layer of mortar laid on blotting paper.

Equipment and materials

For testing use:

· Sheets of blotting paper measuring 150x150 mm according to TU 137308001-758.88;

· Laying from a gauze fabric in the size 250O350 mm in accordance with GOST 11109.90;

· A metal ring with an internal diameter of 100 mm, a height of 12 mm and a wall thickness of 5 mm;

· A glass plate measuring 150-150 mm, 5 mm thick;

· Laboratory scales in accordance with GOST 24104.88;

・Water-holding capacity tester

Preparing for testing and conducting tests

Before testing, 10 sheets of blotting paper are weighed with an error of up to 0.1 g, placed on a glass plate, a gauze pad is placed on top, a metal ring is installed and weighed again. The thoroughly mixed mortar mixture is placed flush with the edges of the metal ring, leveled, weighed and left for 10 minutes.

The metal ring with the solution is carefully removed along with the gauze.

The blotting paper is weighed to the nearest 0.1 g.

Results processing

V = *100,

m1 and m2 - mass of filter paper before and after testing, g;

m3 - mass of the device without mortar mixture, g;

m4 is the mass of the device with the mortar mixture, g.

The water-retaining capacity of the mortar mixture is determined twice for each sample of the mortar mixture and is calculated as an average arithmetic value the results of two determinations that differ from each other by no more than 20% from the lower value.

DETERMINATION OF THE SLABILABILITY OF A SORT MIXTURE

The stratification of the mortar mixture, which characterizes its cohesion under dynamic action, is determined by comparing the mass content of the aggregate in the lower and upper parts of the freshly molded sample with dimensions of 150x150x150 mm.

Equipment

For testing, the following are used: steel molds with dimensions of 150x150x150 mm according to GOST 22685-89;

laboratory vibration platform type 435A;

laboratory scales according to GOST 24104-88;

drying cabinet according to OST 16.0.801.397-87;

sieve with cells 0.14 mm;

baking sheet;

steel rod with a diameter of 12 mm, a length of 300 mm.

4.3. Testing

The mortar mixture is placed and compacted in a mold for control samples with dimensions of 150x150x150mm. After that, the compacted mortar mixture in the form is subjected to vibration on a laboratory vibration platform for 1 min.

After vibrating upper layer solution with a height of (7.5 ± 0.5) mm is taken from the mold onto a baking sheet, and the lower part of the sample is unloaded from the mold by tipping onto the second baking sheet.

The selected samples of the mortar mixture are weighed with an error of up to 2 g and subjected to wet sieving on a sieve with 0.14 mm holes.

In wet sieving, the individual parts of the sample placed on the sieve are washed with a jet clean water until complete removal of the binder. The washing of the mixture is considered complete when clean water flows out of the sieve.

The washed portions of the filler are transferred to a clean baking sheet, dried to constant weight at a temperature of 105-110 ° C and weighed with an error of up to 2 g.

4.4. Results processing

where m1 is the mass of the washed dried aggregate from the upper (lower) part of the sample, g;

m2 is the mass of the mortar mixture taken from the upper (lower) part of the sample, g.

The index of stratification of the mortar mixture P in percent is determined by the formula

where DV is absolute value difference between the content of aggregate in the upper and lower parts of the sample, %;

åV - total content of top and lower parts sample, %.

4.4.3. The stratification index for each sample of the mortar mixture is determined twice and calculated with rounding up to 1% as the arithmetic mean of the results of two determinations that differ from each other by no more than 20% from the lower value. With a greater discrepancy between the results, the determination is repeated on a new sample of the mortar mixture.

21 )Mortar strength for compression is determined on sample cubes with dimensions of 70.7 x 70.7 x 70.7 mm at the age established in the regulatory documentation (or project) on this species solution. Three specimens are made for each test period. To carry out the test, it is necessary to have: detachable steel molds with and without pallets according to GOST 22685, a hydraulic press that ensures the creation of a breaking load on the sample in the range from 20 to 80% of its scale; calipers; rod 12 mm in diameter, 300 mm long; putty knife.

· Samples from mortar mixtures with a mobility of up to 5 cm are made in a form with a pallet. Forms are filled in two layers. The compaction of the layers in each compartment of the form is carried out with 12 spatula pressures: 6 pressures along one side (first layer) and 6 in a perpendicular direction (second layer). Excess mortar is cut flush with the edges with a steel ruler and the surface is smoothed.

· Mortar samples with a mobility of 5 cm or more are made in molds without a pallet. To do this, the form is installed on the bed of a full-bodied ceramic brick covered with newsprint soaked in water. The brick should have a moisture content of no more than 2% and water absorption of 10-15% by weight. To eliminate strong irregularities on the beds, the bricks should be manually rubbed against one another. The mortar mixture is placed in a mold at one time with a slight excess and compacted by bayoneting with a rod 25 times in a spiral from the walls of the mold to the center.

22 )The main indicators of the quality of the hardened solution (concrete):
- compressive strength (except adhesive);
- water absorption;
- frost resistance (except for mixtures for internal works);
- strength of adhesion to the base (adhesion);
- water resistance (for waterproofing and if necessary);
- abrasion (for floor and if necessary);
- frost resistance of the contact zone (except for mixtures for interior work).

23 ) After release from the molds, the samples should be stored at a temperature of (20 ± 2) ° C until testing following conditions storage:

samples from mixtures on hydraulic binders during the first 3 days should be stored in a normal hardening chamber at a relative air humidity of 95-100%, and the remaining time before testing - in a room with a relative air humidity of (65 ± 10)% (from solutions that harden in air) or in water (from solutions that harden in humid environment);

Samples from mixtures prepared with air binders, after stripping, should be stored indoors at a relative humidity of (65 ± 10)%;

Samples from mixtures with chemical antifreeze additives and without them for winter work must be stored in molds outdoors under the same conditions as the structures. From above, the samples must be covered with roofing paper or other rolled materials to prevent water or snow from falling on them. The compression test of these samples should be carried out after 3 hours of thawing within the time period necessary for floor-by-floor control of the mortar strength, as well as after 28 days. hardening after their thawing and storage at a temperature of (20+2) °C. In some cases, stipulated by the project for the production of works, a strength test is carried out for specimens that have hardened for 28 days. at a negative temperature, after their thawing for 3-6 hours, depending on the hardening temperature.

24 ) For testing, apply:

Steel cylindrical vessel with a capacity of 1000 ml

laboratory scales according to GOST 24104-88

steel rod 12 mm in diameter, 300 mm long;
steel ruler 400 mm according to GOST 427-75.

Preparing for testing and conducting tests

Before testing, the vessel is preliminarily weighed with an error of up to 2 g. Then it is filled with an excess of the mortar mixture.

The mortar mixture is compacted by baying with a steel rod 25 times and 5-6 times lightly tapping on the table.

After compaction, the excess mortar mixture is cut off with a steel ruler. The surface is carefully aligned flush with the edges of the vessel. The walls of the measuring vessel are cleaned with a damp cloth from the solution that has fallen on them. The vessel containing the mortar mixture is then weighed to the nearest 2 g.

Results processing
. The density of the mortar mixture, g / cm, is calculated by the formula
,

(1)
where is the mass of the measuring vessel with the mortar mixture, g;

Weight of measuring vessel without mixture, g

26 )Concrete - artificial stone building material obtained by molding and hardening a rationally selected and compacted mixture consisting of binder, coarse and fine aggregates, water

27 ) When designing concrete, it is first necessary to establish the initial data: 1) the required, concrete strength achieved within the specified time: for most structures, the compressive strength of concrete, for road and airfield concrete, the compressive and bending strength, for prefabricated concrete reinforced concrete structures strength grade and tempering strength; 2) the conditions for hardening concrete in the structure: the time of year and average air temperatures, the timing of achieving the required strength, ways to care for concrete; 3) the brand of concrete for frost resistance and water resistance, as well as resistance to chemical corrosion, for which it is necessary to know the operating conditions of the structure (below a constant water horizon, in a zone of variable level, below or above the depth of soil freezing, water aggressiveness, etc.) and climatic conditions of the construction area; 4) configuration, type, massiveness of the structure and degree of reinforcement; 5) materials available for concrete, all their physical and mechanical characteristics; 6) methods and distance of transportation concrete mix; 7) available mechanisms for compacting the concrete mixture.

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. To the main types mortars include solutions for floor screed, filling joints, layers 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, average density 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 the right amount and taking into account the exact dosage, which greatly saves materials and prevents waste.

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 " Specifications colored mosaic compositions":

Acid-resistant solutions based on liquid glass and their composition

Solutions based liquid glass are applied in case of influence of oils and aggressive acids on a surface of facings. 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, the use of ground quartz sand, natural powdered quartz and acid-resistant cement is allowed.

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 a cement surface 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.

Mortar is an artificial stone material obtained by hardening an optimally selected mixture consisting of a binder, water, fine aggregates and additives. Before hardening, the mixture of materials is called a mortar mixture. To give mortar mixtures and mortars certain properties, mineral and chemical additives can be introduced into their composition.

Mortars are fine-grained concretes. They do not have a large filler. Therefore, they are used mainly in the form of thin layers in masonry and plasters, facing works.

In stone buildings, the consumption of mortar is 10–25% of the total volume of the structure. It is used for about 20% of all produced Portland cement.

Mortar mixtures are divided into ready-to-use, pre-made and dry. Ready-to-use mortar mix of binder, fine aggregates, additives and water. Pre-mixed mortar - a mixture of binder, fine aggregate, necessary additives and water to obtain a mobility of 1-3 cm, with the addition of water to the required mobility before use. Dry mortar mixture - a mixture of dry components of a binder, fine aggregate and necessary additives, mixed with water before use.

Mortars are subdivided by purpose, by the type of binder used, by average density.

According to the purpose, the solutions are divided into masonry, plaster, facing, for screeds and special ones. Mounting mortars are also referred to as masonry mortars.

According to the type of binder used, mortars are divided into cement, lime, gypsum, cement-lime, cement-clay, lime-gypsum and others. Solutions prepared on one binder are called simple, on two or more binders - complex.

By average density in a dry state - into heavy (average density 1500 kg / m³ and more) and light (average density less than 1500 kg / m³).

6.2 Mortar properties

The most important properties of the mortar mixture are workability, stratification, viability, spreadability, design application temperature, humidity for dry mixtures.

Workability- the ability of the mortar mixture to be distributed in a thin layer on the base. It affects the quality of the masonry, the mortar mixture fills all the irregularities in the brick and stone - the strength of the masonry increases. When using workable mortar mixes, the productivity of workers increases.

Workability depends on the mobility and water-holding capacity of the mixture.

Mobility is the ability of a mortar mixture to spread under the action of its own mass or applied external influences. It is characterized by the immersion depth in cm of a reference cone weighing 300 g. Mobility is taken depending on the purpose and method of laying the mortar mixture and depends mainly on water consumption.

By mobility, mortar mixtures are divided into grades, which are established depending on the purpose of the mortar mixture according to table 6.1

Table 6.1 – Marks of the working mobility of the mortar mixture

For mortar mixtures of preliminary manufacture, transport mobility with OK from 1 to 3 cm can be assigned.

Water-holding capacity is the property of a mortar mixture to retain water in its composition when laid on a porous base. Brick, concrete and other porous materials absorb water well and can absorb it from the mortar. There is not enough water left to harden the binder, and the solution does not reach the required strength.

The water-holding capacity of the mortar mixture is determined on a device consisting of a ring with a diameter of 100 mm and a height of 12 mm and blotting paper. The ring is filled with the mortar mixture and the water-holding capacity is determined by the amount of water remaining in the mortar mixture after some of it has been sucked off with blotting paper.

The water-holding capacity of the mortar mixture with OK over 4 cm should be at least 95%. The mortar mixture has good water-retaining capacity if the strength of samples made in molds without a bottom, mounted on bricks, will be 15% higher than the strength of samples made in molds with a metal bottom.

The water-holding capacity increases with an increase in the consumption of cement, the introduction of lime, clay, ash, and other mineral and some chemical additives into the mortar mixture.

Delamination- Heterogeneity of the mortar mixture in height, formed during transportation and storage. Delamination is determined in the form of a cube measuring 150x150x150 mm. The mold is filled with a mortar mixture, compacted manually by baying, and then by vibrating. Then the mixture is divided into two parts and after washing, the sand content in the upper and lower parts is determined. The stratification of freshly prepared mortar mixtures should not exceed 10%.

The stratification comes from insufficient bonding of the particles of the mixture. Low-grade solutions contain little binder, especially high grades, and an increased amount of water. The cohesiveness of the mortar mixture is reduced, which leads to its stratification. To prevent delamination, lime and clay dough, plasticizing chemical additives that bind water or reduce its content should be introduced.

vitality called the property of the mortar mixture to maintain the necessary workability from the beginning of its preparation to laying in the structure. It depends on the composition of the mixture and the outside temperature. The pot life of cement mortars is usually 2–4 hours and depends on the setting time of the cement. Lime mortar mixtures on hydrated lime have a viability of 6–10 hours, complex cement-lime mixtures - 4–6 hours.

At elevated temperatures, mortar mixtures containing Portland cement should be consumed within 2 hours. It is possible to extend their viability by introducing additives that slow down the setting of cement. Seized mixtures must not be diluted with water.

Spreadability mortar mixtures is installed for self-leveling screeds. It is determined by the spread of the cylinder and must be at least 22 cm.

Design temperature the use of mortar mixtures is set at the expected average daily air temperature below plus 5 °C and the minimum average daily temperature below 0 °C. It is achieved by introducing antifreeze additives into the mortar mixture with the condition that the mortar at the design temperature of use has at least 20% of the grade strength of the mortar without additives, hardened at (20 ± 3) ˚С.

For dry mortar mixtures, humidity is normalized. It depends on the type of binder used and should not exceed the following values: for mixtures containing gypsum binders - 0.3% by weight; for mixtures containing cement binder at consumption up to 150 kg/t - 0.6, up to 300 kg/t - 0.8, over 300 kg/t - 1.0%.

cement mortars prepared from cement, sand and water and used in damp and damp places. These solutions plaster the exterior Wall panels, plinths. With the introduction of special additives, they are used to make an insulating layer. Cement mortars are very strong, but rigid (low plasticity). The plasticity of solutions is increased by introducing additives. The compositions of the solutions are used in the ratio by weight: from 1:1 to 1:6. Solutions in the ratio from 1:6 to 1:4 are considered hard and inconvenient to use. AT plastering works ah, most often a solution is used in a ratio of 1: 3 (Table 2.5).

Lime mortars are prepared from lime paste and sand. They are used in the production of plastering work indoors on stone and concrete surfaces. In humid rooms, these solutions are not used.

Table 2.5. Compositions of some solutions

The solutions have good mobility and plasticity, harden immediately and have a relatively low strength. The amount of sand in the solutions depends on the purpose of the plaster layer and the lime used. Very often, lime mortars come with the addition of cement or gypsum.

Lime-gypsum mortars. To speed up hardening, gypsum is added to lime mortars in a ratio of 1: 0.25 to 1: 1. They are intended for plastering stone and wooden surfaces. Eaves are well drawn out of this solution. Lime-gypsum mortar is prepared in small portions in order to a short time You could use it and make a new one.

Cement-lime mortars prepared from cement, lime paste and sand. Used for plastering exterior walls
dampening parts of buildings, bathrooms, external slopes. Composition - : lime paste: sand 1: (%6/-1) : (3…5).
The viability of the solution is 1 hour. These solutions are more plastic than cement ones, they are easily leveled with a thin layer and delaminate less than cement ones. The brand of mortar depends on the brand of cement.

Solutions from dry mixes. The dry mixture is produced centrally from Portland cement, dry fine river sand with the addition of lime
flour. Used for coating layer, making rustications and joints of reinforced concrete products. They produce a mixture of grades 50, 75, 100, 150.

Terrazit mixes consist of binder material and aggregates of different sizes (crumb, glass, mica) and pigments.
Terrazit mortar is prepared immediately before application by mixing with water to the required consistency.

stone mixtures contain colored cements (there may be an additive of lime paste), crumbs of various rocks and pigments.

Cement-lime mixtures consist of cement (80%), hydrated lime (20%) and pigments. Designed for plastering wet surfaces. From dry mixtures or individual components, decorative solutions are prepared for plastering building facades immediately before application.

· Building mixture - combines the concepts of "mortar mixture", "dry mortar mixture", "solution". A mortar is a material obtained as a result of the hardening of a mixture of a binder (cement), fine aggregate (sand), aggregator (water) and in necessary cases special additives. This mixture before the start of hardening is called a mortar mixture. Dry mortar is a mixture of dry components - binder, filler and additives, dosed and mixed at the factory - mixed with water before use.

The binder in the solution envelops the aggregate grains, reducing friction between them, as a result of which the mortar mixture acquires the mobility necessary for work. During the hardening process, the binder firmly binds the individual aggregate particles together. Cement, clay, gypsum, lime or mixtures thereof are used as a binder, and as a filler - sand.

Mortars are classified depending on a number of factors: the binder used, the properties of the binder, the ratio between the amount of binder and aggregate, density and purpose.

There are several ways to classify solutions. So, based on

the value of electrical conductivity, distinguish between electrolyte solutions and

non-electrolytes. Solutions can be classified according to state of aggregation

system and the particles of which it is composed.

A solution can be classified according to the amount of solute in it.

present. If molecular or ionic particles distributed in a liquid

solution, are present in it in such an amount that under these conditions not

further dissolution of the substance occurs, the solution is called saturated.

(For example, if you place 50 g of NaCl in 100 g of H 2 O, then at 20ºC

only 36 g of salt will dissolve). A saturated solution is one that is

in dynamic equilibrium with an excess of solute. By placing in 100 g

water at 20ºC less than 36 g of NaCl, we get an unsaturated solution. At

heating a mixture of salt and water to 100 ○ C will dissolve

39.8 g NaCl in 100 g water. If we now remove the undissolved

salt, and the solution is carefully cooled to 20ºC, excess salt is not

always falls out. In this case, we are dealing with a supersaturated

solution. Supersaturated solutions are very unstable. Stirring,

shaking, adding grains of salt may cause crystallization of excess

salt and transition to a saturated stable state.

From the point of view of thermodynamics, one can distinguish between ideal solutions and non-ideal (or

real).

In ideal solutions, to which real ones can only

approach, the internal energy of each component does not depend on

concentration. Components in an ideal solution mix as ideal

gases; it is assumed that there are no interaction forces between particles, and substances

mix without release or absorption of heat.

Solutions that do not meet the specified conditions are referred to as real solutions.

solutions. The lower the concentration of the solution, the closer it is to ideal.

solution. Solutions of isotopes of one element in another almost exactly obey

laws of ideal solutions. Homogeneous mixtures of non-polar substances

(hydrocarbons) are close to ideal solutions at all concentrations.

Solutions of polar substances, especially electrolytes, show a noticeable

deviation from ideality already at concentrations corresponding to the mole fraction

about one millionth.

cement mortar, Lime and lime-gypsum mortars, Whole material mortar, Screened material mortar, Clay mortar, etc.

Properties of mortar mixtures

Workability - the property of the mortar mixture is easy to fit in a dense and thin layer on a porous base and not delaminate during storage, transportation and pumping.
It depends on the plasticity (mobility) and water-holding capacity of the mixture.

Plastic mixtures characterize its mobility, i.e., the ability to spread under the action of its own weight or external forces applied to it. The mobility of almost all mortar mixtures is determined by the immersion depth (in cm) of a standard cone with a mass of (300:4:2) g.
Cone height 180 mm, base diameter 150 mm, apex angle 30°.
In the laboratory, the cone is mounted on a tripod, under conditions construction site hung on a chain with a ring

Cone 3, held by the ring, is brought to the mixture so that its apex touches its surface. Then the cone is released and it sinks into the mixture under its own weight.
The divisions on a scale of 6 or on the surface of the cone determine the depth of its immersion in the mixture. If the cone is immersed to a depth of 6 cm, this means that the mobility of the mortar mixture is 6 cm.

The mobility of the mortar mixture depends primarily on the amount of water and binder, the type of binder and aggregate, the ratio between binder and aggregate. Fatty mortars are more mobile than lean ones. Ceteris paribus, solutions on lime and clay are more mobile than on cement; solutions on natural sand are more mobile than solutions on artificial sand (crushed).
The type of binder is selected and the composition of the solution is set depending on the required strength of the solution and the operating conditions of the building.

The mobility of the mortar mixture can be adjusted by increasing or decreasing the consumption of binder or water. By increasing the content of water and binder in the mortar mixture, more plastic (mobile) and workable mixtures are obtained.

A workable mortar mixture is obtained with a correctly assigned grain composition of its solid components (sand, binder, additives). The binder dough not only fills the voids between the grains of sand, but also evenly envelops the grains of sand with a thin layer, reducing internal friction.
Mortar mix with normal water-retaining capacity - easy to process and work to be laid, soft, does not reach for the plasterer's shovel, provides high labor productivity.

The quality of masonry and plaster depends on the workability of the mixture.
Properly selected and well-mixed mortar mix densely fills irregularities, depressions, cracks in the base, so it turns out big square contact between the mortar and the base, as a result, the solidity of the masonry and plaster increases, and their durability increases.

Delamination- the ability of the mortar mixture to separate into solid and liquid fractions during transportation and pumping it through pipes and hoses.
The mortar mix is ​​often transported by dump trucks and moved through pipelines using mortar pumps. At the same time, it is not uncommon for the mixture to separate into water (liquid phase) and sand and binder (solid phase), as a result of which plugs can form in pipes and hoses, the elimination of which is associated with heavy losses labor and time.
The stratification of the mortar mixture is determined in the laboratory.

You can check the mixture for stratification in a simplified way as follows. A mortar mixture is placed in a bucket with a layer about 30 cm high and its mobility is determined by a reference cone. Take off after 30 minutes upper part solution (about 20 cm) and again determine the depth of immersion of the cone. If the difference in cone immersion values ​​is close to zero, then the mortar mixture is considered non-separable, if it is within 2 cm, the mixture is considered to be of medium segregation.
The difference in cone immersion values ​​of more than 2 cm indicates that the mortar mixture is stratified.

If the composition of the mortar mixture is chosen correctly and the water-binding ratio is set correctly, then the mortar mixture will be mobile, workable, it will have good water-retaining capacity and will not delaminate.
Plasticizing additives, both inorganic and organic, increase the water-holding capacity of mortar mixtures and reduce their stratification

Dry building mixtures - these are factory-prepared mixtures of loose building materials strictly according to the specifications building materials(sand, cement, gypsum) with the possible addition of special chemical additives (the better and narrower the additive, the more expensive the price of the dry mix). Dry mixes are usually packaged and packed in 1, 3, 5, 10 kg and are used for further preparation of solutions that are used for:

• Rough floor screed, leveling the floor with a self-leveling mortar.
• Construction adhesive, tile adhesive.
• Plasters, putties.
• Sealants, primers.
• Waterproofing.

Parts of a growing tree. A growing tree consists of a crown, trunk and roots. During the life of a tree, each of these parts performs its specific functions and has a different industrial application.

Crown consists of branches and leaves (or needles). From carbon dioxide absorbed from the air and water obtained from the soil, complex organic substances are formed in the leaves, which are necessary for the growth of the tree. The industrial use of the crown is not great. Vitamin flour is obtained from the leaves (needles) - a valuable product for animal husbandry and poultry farming, medications, from branches - technological chips for the production of containerboard and fibreboard.

Trunk a growing tree conducts water with dissolved minerals upwards (ascending current), and with organic substances - down to the roots (descending current); stores spare nutrients; serves to accommodate and maintain the crown. It gives the bulk of the wood (from 50 to 90% of the volume of the whole tree) and is of major industrial importance. The upper thin part of the trunk is called the top, the lower thick part is called the butt.
Figure 1b shows the development process coniferous tree from a seed and a scheme for constructing a tree trunk at the age of 13 years. The growth process can be thought of as the growth of cone-shaped layers of wood. Each subsequent cone has a greater height and base diameter. The figure shows 10 concentric circles (boundaries of annual increments) on the lower cross section, and on the upper same section there are only five of them.

Roots conduct water with minerals dissolved in it up the trunk; keep stocks nutrients and keep the tree upright. Roots are used as secondary fuel. Stumps and large roots of pine, some time after felling trees, serve as raw materials for obtaining rosin and turpentine.

· Macroscopic structure of wood