Cement mortar m50. What you need for a strong cement mortar: proportion calculator. Proportions for the preparation of mortars

GOST 28013-98

Group G13

INTERSTATE STANDARD

BUILDING SOLUTIONS

General specifications

General specifications

ISS 91.100.10
OKSTU 5870

Introduction date 1999-07-01

Foreword

Foreword

1 DEVELOPED by the State Central Research and Design Institute of Complex Problems of Building Structures and Structures named after V.A. Kucherenko (TsNIISK named after V.A. Kucherenko), Research, Design and Technological Institute of Concrete and Reinforced Concrete ( NIIZhB), with the participation of CJSC "Pilot Plant of Dry Mixes" and JSC "Roskonitstroy" of the Russian Federation

INTRODUCED by Gosstroy of Russia

2 ADOPTED by the Interstate Scientific and Technical Commission for Standardization, Technical Regulation and Certification in Construction (ISTCS) on November 12, 1998

voted to accept

3 INSTEAD OF GOST 28013-89

4 INTRODUCED from July 1, 1999 as the state standard of the Russian Federation by the Decree of the Gosstroy of Russia dated November 29, 1998 N 30

5 EDITION (July 2018), with Amendment No. 1 (IUS 11-2002)


Information about changes to this standard is published in the annual information index "National Standards", and the text of changes and amendments - in the monthly information index "National Standards". In case of revision (replacement) or cancellation of this standard, a corresponding notice will be published in the monthly information index "National Standards". Relevant information, notification and texts are also posted in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet (www.gost.ru)

1 area of ​​use

This standard applies to mortars based on mineral binders used for masonry and installation of building structures during the construction of buildings and structures, fastening of facing products, plaster.

The standard does not apply to special mortars (heat-resistant, chemically resistant, fire-resistant, heat and waterproofing, grouting, decorative, straining, etc.).

The requirements set out in 4.3-4.13, 4.14.2-4.14.14, sections 5-7, appendices C and D of this standard are mandatory.

2 Normative references

The normative documents used in this standard are given in Appendix A.

3 Classification

3.1 Mortars are classified according to:

- main purpose;

- used binder;

- medium density.

3.1.1 According to the main purpose, solutions are divided into:

- masonry (including for installation works);

- facing;

- plastering.

3.1.2 According to the binder used, the solutions are divided into:

- simple (on a binder of the same type);

- complex (on mixed binders).

3.1.3 According to the average density, the solutions are divided into:

- heavy;

- lungs.

3.2 The reference designation of the mortar when ordering should consist of an abbreviated designation indicating the degree of readiness (for dry mortar mixes), purpose, type of binder used, grades for strength and mobility, average density (for light mortars) and the designation of this standard.

An example of a symbol for a heavy mortar, ready for use, masonry, on a lime-gypsum binder, strength grade M100, mobility - P2:

Masonry mortar, lime-gypsum, M100, P2, GOST 28013-98 .

For a dry mortar mixture, light, plaster, cement binder, strength grade M50 and mobility - P3, medium density D900:

Mix dry mortar plaster, cement, M50, P3, D900, GOST 28013-98 .

4 General technical requirements

4.1 Mortars are prepared in accordance with the requirements of this standard according to the technological regulations approved by the manufacturer.

4.2 Properties of mortars include properties of mortar mixtures and hardened mortar.

4.2.1 Basic properties of mortar mixtures:

- mobility;

- water holding capacity;

- stratification;

- application temperature;

- average density;

- humidity (for dry mortar mixtures).

4.2.2 Main properties of the hardened mortar:

- compressive strength;

- frost resistance;

- average density.

If necessary, additional indicators can be set in accordance with GOST 4.233.

4.3 Depending on the mobility, mortar mixtures are subdivided in accordance with table 1.


Table 1

4.4 Water-holding capacity of mortar mixtures should be at least 90%, clay-containing solutions - at least 93%.

4.5 The delamination of freshly prepared mixtures should not exceed 10%.

4.6 The mortar mixture should not contain fly ash of more than 20% by weight of cement.

4.7 The temperature of mortar mixtures at the time of use should be:

a) masonry mortars for outdoor work - in accordance with the instructions in table 2;

b) facing mortars for cladding with glazed tiles at a minimum outdoor temperature, °C, not less than:

c) plaster mortars at a minimum outdoor temperature, °C, not less than:

table 2

4.8 The moisture content of dry mortar mixtures should not exceed 0.1% by weight.

4.9 Normalized indicators of the quality of the hardened mortar must be provided at the design age.

For the design age of the mortar, unless otherwise specified in the project documentation, 28 days should be taken for mortars on all types of binders, except for gypsum and gypsum-containing ones.

The design age of mortars on gypsum and gypsum-containing binders is 7 days.

(Changed edition, Rev. N 1).

4.10 The compressive strength of mortars at design age is characterized by grades: M4, M10, M25, M50, M75, M100, M150, M200.

The compressive strength grade is assigned and controlled for all types of solutions.

4.11 Frost resistance of solutions is characterized by grades.

For solutions, the following frost resistance grades are established: F10, F15, F25, F35, F50, F75, F100, F150, F200.

For solutions of grades for compressive strength M4 and M10, as well as for solutions prepared without the use of hydraulic binders, frost resistance grades are not assigned and not controlled.

4.12 The average density, , of hardened solutions at the design age should be, kg/m:

The normalized value of the average density of the solutions is set by the consumer in accordance with the work project.

4.13 Deviation of the average density of the solution in the direction of increase is allowed no more than 10% of the one established by the project.

4.14 Requirements for materials for the preparation of mortars

4.14.1 Materials used for the preparation of mortars must comply with the requirements of standards or specifications for these materials, as well as the requirements of this standard.

4.14.2 The following should be used as binders:

- gypsum binders according to GOST 125;

- building lime according to GOST 9179;

- Portland cement and Portland slag cement according to GOST 10178;

- pozzolanic and sulfate-resistant cements according to GOST 22266;

- cements for mortars according to GOST 25328;

- clay according to Appendix B;

- others, including mixed binders, according to regulatory documents for a specific type of binders.

4.14.3 Binder materials for the preparation of solutions should be selected depending on their purpose, type of structures and conditions of their operation.

4.14.4 The consumption of cement per 1 m of sand in mortars based on cement and cement-containing binders must be at least 100 kg, and for masonry mortars, depending on the type of structures and their operating conditions, not less than that given in Appendix D.

4.14.6 Lime binder is used in the form of hydrated lime (fluff), lime paste, lime milk.

The milk of lime must have a density of at least 1200 kg/m3 and contain at least 30% lime by weight.

Lime binder for plastering and facing mortars must not contain unextinguished lime particles.

The lime paste must have a temperature of at least 5°C.

4.14.7 The following should be used as a placeholder:

- sand for construction works in accordance with GOST 8736;

- fly ash according to GOST 25818;

- ash and slag sand according to GOST 25592;

- porous sands according to GOST 25820;

- sand from slags of thermal power plants according to GOST 26644;

- sand from slags of ferrous and non-ferrous metallurgy for concrete according to GOST 5578.

4.14.8 The largest aggregate grain size should be, mm, not more than:

4.14.9 When heating aggregates, their temperature, depending on the binder used, should not be higher, °С, when using:

4.14.11 The specific effective activity of natural radionuclides of materials used for the preparation of mortar mixtures should not exceed the limit values ​​depending on the field of application of mortar mixtures in accordance with GOST 30108.

4.14.12 Chemical additives must comply with the requirements of GOST 24211.

Additives are introduced into ready-to-use mortar mixtures in the form of aqueous solutions or aqueous suspensions, into dry mortar mixtures - in the form of a water-soluble powder or granules.

4.14.13 Water for mixing mortar mixtures and preparing additives is used in accordance with GOST 23732.

4.14.14 Bulk raw materials for mortar mixtures are dosed by weight, liquid components are dosed by weight or volume.

Dosing error should not exceed ± 1% for binders, water and additives, ± 2% aggregates.

For mortar mixing plants with a capacity of up to 5 m/h, volumetric dosing of all materials is allowed with the same errors.

4.15 Marking, packaging

4.15.1 Dry mortar mixtures are packed in polyethylene film bags according to GOST 10354 weighing up to 8 kg or paper bags according to GOST 2226 weighing up to 50 kg.

4.15.2 Packaged dry mortar mixes should be marked on each package. The marking must be clearly marked on the packaging with indelible ink.

4.15.3 Mortar mixtures must have a quality document.

The manufacturer must accompany the dry mortar mix with a label or marking applied to the package, and the ready-to-use mortar released into the vehicle with a quality document, which should contain the following data:

- name or trademark and address of the manufacturer;

- symbol of the mortar according to 3.2;

- the class of materials used to prepare the mixture, according to the specific effective activity of natural radionuclides and the digital value ;

- brand for compressive strength;

- mark on mobility (P);

- the volume of water required for the preparation of the mortar mixture, l / kg (for dry mortar mixtures);

- the type and amount of the added additive (% of the mass of the binder);

- shelf life (for dry mortar mixes), months;

- mass (for dry mortar mixtures), kg;

- the amount of the mixture (for mortar mixtures ready for use), m;

- date of preparation;

- application temperature, °C;

- designation of this standard.

If necessary, the marking and the quality document may contain additional data.

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

5 Acceptance rules

5.1 Mortar mixtures should be accepted by the manufacturer's technical control.

5.2 Mortar mixtures and solutions are accepted in batches by carrying out acceptance and periodic control.

A batch of a mortar mixture and a solution is taken as the amount of a mixture of one nominal composition with the same quality of its constituent materials, prepared according to a single technology.

The volume of the batch is set in agreement with the consumer - not less than the output of one shift, but not more than the daily output of the mortar mixer.

5.3 All mortar mixtures and solutions are subject to acceptance control according to all standardized quality indicators.

5.4 When accepting each batch, at least five point samples are taken from the mortar mixture.

5.4.1 Incremental samples are taken at the place of preparation of the mortar mixture and / or at the place of its application from several batches or places of the container into which the mixture is loaded. Tank sampling points should be located at different depths. With a continuous supply of the mortar mixture, point samples are taken at unequal time intervals for 5-10 minutes.

5.4.2 After sampling, point samples are combined into a general sample, the mass of which should be sufficient to determine all controlled indicators of the quality of mortar mixtures and solutions. The sample taken is thoroughly mixed before testing (with the exception of mixtures containing air-entraining additives).

Mortar mixtures containing air-entraining, foaming and gas-forming additives are not additionally mixed before testing.

5.4.3 Testing of the ready-to-use mortar mixture should begin during the period of maintaining the normalized mobility.

5.5 The mobility and average density of the mortar mixture in each batch is controlled at least once per shift at the manufacturer after unloading the mixture from the mixer.

The moisture content of dry mortar mixtures is controlled in each batch.

The strength of the solution is determined in each batch of the mixture.

The normalized technological indicators of the quality of the mortar mixtures provided for in the supply contract (average density, temperature, stratification, water-holding capacity), and the frost resistance of the mortar are controlled in time as agreed with the consumer, but at least once every 6 months, as well as when the quality of the initial materials, composition of the solution and technology of its preparation.

5.6 Radiation-hygienic assessment of materials used for the preparation of mortar mixtures is carried out according to the quality documents issued by the enterprises - suppliers of these materials.

In the absence of data on the content of natural radionuclides, the manufacturer determines the specific effective activity of natural radionuclides of materials according to GOST 30108 once a year, as well as at each change of supplier.

5.7 Mortar mixtures ready for use are dispensed and taken by volume. The volume of the mortar mixture is determined by the output of the mortar mixer or by the volume of the transport or measuring tank.

Dry mortar mixtures are dispensed and taken by weight.

5.8 If, when checking the quality of the mortar, a discrepancy is revealed in at least one of the technical requirements of the standard, this batch of mortar is rejected.

5.9 The consumer has the right to carry out a control check of the quantity and quality of the mortar mixture in accordance with the requirements of this standard according to the methods of GOST 5802.

5.10 The manufacturer is obliged to inform the consumer, at his request, of the results of control tests no later than 3 days after their completion, and in case of non-confirmation of the normalized indicator, inform the consumer immediately.

6 Control methods

6.1 Mortar samples are taken in accordance with the requirements of 5.4, 5.4.1 and 5.4.2.

6.2 Materials for the preparation of mortar mixtures are tested in accordance with the requirements of the standards and specifications for these materials.

6.3 The quality of chemical additives is determined in terms of the effectiveness of their action on the properties of mortars in accordance with GOST 30459.

6.4 The concentration of the working solution of additives is determined by a hydrometer according to GOST 18481 in accordance with the requirements of standards and specifications for additives of specific types.

6.5 The specific effective activity of natural radionuclides in materials for the preparation of mortar mixtures is determined according to GOST 30108.

6.6 Mobility, average density, water-holding capacity and stratification of mortar mixtures are determined according to GOST 5802.

6.7 The volume of air involved in mortar mixtures is determined according to GOST 10181.

6.8 The temperature of freshly prepared mortar mixtures is measured with a thermometer, immersing it in the mixture to a depth of at least 5 cm.

6.9 Compressive strength, frost resistance and average density of hardened solutions are determined according to GOST 5802.

6.10 The moisture content of dry mortar mixtures is determined according to GOST 8735.

7 Transport and storage

7.1 Transport

7.1.1 Ready-to-use mortar mixtures should be delivered to the consumer in vehicles specially designed for their transportation.

With the consent of the consumer, transportation of mixtures in bunkers (buckets) is allowed.

7.1.2 The methods used for transporting mortar mixtures should exclude the loss of astringent dough, the ingress of atmospheric precipitation and impurities into the mixture.

7.1.3 Packed dry mortar mixes are transported by road, rail and other modes of transport in accordance with the rules for the carriage and securing of goods in force for this type of transport.

7.2 Storage

7.2.1 Mortar mixtures delivered to the construction site, ready for use, must be reloaded into mixers or other containers, provided that the specified properties of the mixtures are preserved.

7.2.2 Packed mortar dry mixes are stored in covered dry rooms.

Bags with a dry mix should be stored at a temperature not lower than 5°C under conditions that ensure the safety of the packaging and protection from moisture.

7.2.3 The shelf life of the dry mortar mixture is 6 months from the date of preparation.

At the end of the shelf life, the mixture should be checked for compliance with the requirements of this standard. In case of compliance, the mixture can be used for its intended purpose.

APPENDIX A (informative). List of regulatory documents

APPENDIX A
(reference)

GOST 4.233-86 SPKP. Construction. Building solutions. Nomenclature of indicators

GOST 125-79 Gypsum binders. Specifications

GOST 2226-2013 Bags made of paper and combined materials. General specifications

GOST 2642.5-2016 Refractories and refractory raw materials. Methods for the determination of iron oxide (III)

GOST 2642.11-97 Refractories and refractory raw materials. Methods for determination of potassium and sodium oxides

GOST 3594.4-77 Molding clays. Methods for determining the sulfur content

GOST 5578-94 Crushed stone and sand from slags of ferrous and non-ferrous metallurgy for concrete. Specifications

GOST 5802-86 Building mortars. Test Methods

GOST 8735-88 Sand for construction work. Test Methods

GOST 8736-2014 Sand for construction work. Specifications

GOST 9179-77 Building lime. Specifications

GOST 10178-85 Portland cement and Portland slag cement. Specifications

GOST 10181-2014 Concrete mixes. Test Methods

GOST 10354-82 Polyethylene film. Specifications

GOST 18481-81 Hydrometers and glass cylinders. Specifications

GOST 21216-2014

GOST 21216-2014 Clay raw materials. Test Methods

GOST 22266-2013 Sulphate-resistant cements. Specifications

GOST 23732-2011 Water for concrete and mortar. Specifications

GOST 24211-2008 Additives for concrete and mortars. General specifications

GOST 25328-82 Cement for mortars. Specifications

GOST 25592-91 Ash and slag mixtures for thermal power plants for concrete. Specifications

GOST 25818-2017 Fly ash from thermal power plants for concrete. Specifications

GOST 25820-2000 Lightweight concrete. Specifications

GOST 26633-2015 Heavy and fine-grained concrete. Specifications

GOST 26644-85 Crushed stone and sand from slags of thermal power plants for concrete. Specifications

GOST 30108-94 Construction materials and products. Determination of specific effective activity of natural radionuclides

GOST 30459-2008 Additives for concrete. Methods for determining efficiency

SNiP II-3-79* Construction heat engineering

APPENDIX B (recommended). The mobility of the mortar mixture at the site of application, depending on the purpose of the solution

Table B.1

APPENDIX B (mandatory). Clay for mortars. Technical requirements

APPENDIX B
(mandatory)

These technical requirements apply to clay intended for the preparation of mortars.

B.1 Clay specifications

B.1.3 The content of chemical components from the mass of dry clay should not be more than,%:

- sulfates and sulfides in terms of - 1;

- sulfide sulfur in terms of - 0.3;

- mica - 3;

- soluble salts (causing efflorescence and efflorescence):

the amount of iron oxides - 14;

the sum of potassium and sodium oxides is 7.

B.1.4 Clay shall not contain organic impurities in quantities that give a dark color.

B.2 Test methods for clay

B.2.1 The granulometric composition of clay is determined according to GOST 21216.2 and GOST 21216.12. B.2.4 The mica content is determined by the petrographic method according to

Operating conditions of enclosing structures, humidity conditions of premises according to SNiP II-3-79*

Minimum consumption of cement in masonry mortar per 1 m of dry sand, kg

Under dry and normal room conditions

In humid conditions

In wet conditions

Electronic text of the document

prepared by Kodeks JSC and verified against:
official publication
M.: Standartinform, 2018

Each M 50 solution has its own characteristics. Some of them are used to create brickwork, others - for stone. Cement-lime mortars grade 50 are used for bricks throughout Russia, and Nizhny Novgorod is no exception. Theoretically, each builder can make such a solution on their own, but in practice, maintaining proportions is very important. Therefore, to obtain a high-quality M 50, it is better to purchase it ready-made at a specialized enterprise in Nizhny Novgorod.

Composition M 50

The M50 solution belongs to the complex category, since a filler is used in its manufacture. Usually, grains of reclaimed river sand serve as a filler. Finding it on your own is quite difficult. In addition to sand, the composition of the solution includes water, as well as lime. In order for the solution to meet its intended purpose, it is necessary to strictly observe all the available proportions.

The correct composition would be:

• cement - 1 share;
• lime - 0.7 shares;
• sand - 6 shares.

Characteristics of the M50

According to GOST 28013-98, the M 50 solution is characterized by frost resistance F50 (the ability to endure 50 freezing cycles), as well as class B-3.5. The water permeability of the solution is quite low - the coefficient W2, i.e. it is unstable to the effects of a humid environment. Therefore, laying it requires special skills.

Where to buy M 50?

JSC "ZHELEZOBETONSTROY No. 5" in Nizhny Novgorod sells a variety of concrete products and cement mortars, including cement mortar M50 at a low price. Products meet all existing quality standards. The client has the opportunity to order the delivery of goods. Payment is accepted both in cash and by bank transfer.

Cement is an artificial inorganic binder that, when water, saline aqueous solutions, and other liquids are added, forms a plastic mass, which subsequently hardens, turning into a stone-like body.

It is used for the production of concrete and mortars. Now the most popular brands are M (PC) 400 and M500.

Acquisition of high-quality binding material

1. It is better to buy in specialized hardware stores and supermarkets, and not in the market.
2. It is necessary to carefully examine the integrity of the packaging and all inscriptions. It is very important that the shelf life does not exceed six months. The fresher the better. And to avoid forgery, you need to check the quality certificate.
3. The presence of lumps is unacceptable, and the popular method of quality control is as follows: they collect cement in a handful and clench their palm into a fist. If it seeps through the fingers, then the material is good, but if it is compacted in the hand, this should not be taken.
4. It is not recommended to stock up for future use, it is advisable to use it immediately after purchase, and if a certain amount remains after the work done, then it must be stored strictly in a place protected from moisture, additionally placed in sealed plastic bags, tightly tied.

Proportions for the preparation of mortars

Many people think that the M400 or M500 brand is an indication of what proportion should be followed to prepare the mixture. This is not true. The number indicates that the cement can withstand a load of 400 or 500 kg/cm 2 respectively. How to dilute cement?

In the tables of the Instructions for the preparation and use of building mortars CH 290-74, strictly regulated proportions are indicated.

So solutions are divided into:

1. Plaster solutions: grades M10, M25, M50;
2. Masonry mortars: grades M50, M75, M100, M125, M150, M200;
3. for screed: brand M150, M200.

1. Water is mixed with a binder, cement milk is obtained, to which sand is added.
2. The second option is preferable: first you mix cement with sand, and then you add water. This guarantees the homogeneity of the resulting cement mass and the quality of construction work.

When preparing a cement-lime or cement-clay mortar, first the lime (clay) dough is diluted with water to the consistency of milk and passed through a sieve with 10x10 mm cells. Then add it to the already mixed mixture of sand with a binder.

For plastering, clean river sand is used, and quarry sand can also be used for masonry. Before use, the sand is sifted through a 10x10 mm sieve. Often in individual construction, an old armored mesh from a bed is used for these purposes.

The amount of water is already determined during the production of the mixture, judging from the consistency of the mixture.

To mix the solutions manually, use a shovel, a construction mixer. But still it is better to purchase an electric concrete mixer for large volumes of construction work. To deliver the solution, ordinary buckets, stretchers or a wheelbarrow are used. Don't forget gloves and goggles.

Cement-lime mortar is a mixture with high adhesion, strength and elasticity. It has proven itself as a masonry mortar for building blocks and bricks, as well as for plastering various surfaces indoors and outdoors. The scope of application is not limited to finishing works, this also includes laying pipes, processing reinforcing mesh, pouring monolithic floors. One of the most important advantages of such a composition is reliability and moisture resistance.

In addition to the above properties, lime is also characterized by bactericidal properties that prevent the formation of fungi and molds. It is worth noting, unlike cement mortar, the ability of the material to pass moisture, which has a positive effect on the level of humidity inside the room. Hence resistance to temperature extremes up to 65 °C and frost resistance down to -50 °C.

Good adhesive properties make it possible to work with any materials, even with wood. The mixture is easy to lay, filling even the smallest cracks and bumps. The increased plasticity of the lime mortar makes it possible to extend the drying time to three hours, thereby avoiding cracking.

According to the characteristics of fat content, the following lime compositions are distinguished:

1. normal - with an optimal degree of plasticity, practically do not crack and shrink when dried;

2. skinny - used for any facing work, as they have minimal shrinkage;

3. greasy - a highly plastic material with a large amount of binders, therefore it is well used as a masonry mortar.

Fat content can be adjusted by adding various components. So, to lower the value, porous sand is added, and lime increases the fat content back.

According to the ratio of density, solutions are divided into:

• low density - up to 1500 kg/m3;
• medium density - from 1500 kg / m3.

The ratio of the components of the solution determines the scope of its application. The most popular brands are M75 and M50. For example, the M75 mixture proved to be the best as a reliable masonry mortar for bricks. Whereas for a wider area of ​​​​use, as well as for plastering work, we digest M50.

With regard to plaster mixtures, they are conditionally divided into:

1. basic - for rough leveling of the surfaces of walls and ceilings;

2. decorative - having decorative elements in the structure or due to prolonged drying, they are easily subjected to textured processing with subsequent painting;

3. special - are of a technical nature to improve the moisture-proof properties, sound insulation and insulation.

Manufacturers and prices

Another plus is the affordable cost of the material compared to the cement-sand mortar. Its low consumption (1 m2 layer in 1 mm - 1.5 kg of the mixture) determines the economic benefits. Lime mortar can be bought from manufacturers ready-made or in the form of a dry mix packaged in bags. Construction manipulations indoors are allowed to be carried out with powder compositions, while for outdoor work, especially under conditions of high humidity, it is recommended to entrust the preparation to professionals.

The cost depends on the quality of the raw materials used, the ratio of ingredients. An approximate price range is shown in the table below.

The line of manufacturers of ready-made dry mixes is quite extensive. All of them have their own characteristics, features in the composition and scope. Below are the most accessible and common.

Do-it-yourself solution preparation

In addition to ready-made production options, it is possible to make lime mortar yourself. Buy all the necessary high-quality elements and carefully observe the proportions to achieve a high-quality result while saving money. The main ingredients used are cement, sand, lime and water.

The ratio of ingredients determines the brand and specifications.

Water consumption during preparation is usually 0.8 parts per 1 hour of cement. In practice, the amount of liquid is determined visually by the consistency of the solution - normally, the mixture should look like thick sour cream.

Lime, as a building material, is used only in a quenched form, otherwise, as a result of a chemical reaction, the finished material may swell or burst completely. For preparation, you will need a separate container. The process differs depending on the rate of quenching.

1. Fast-extinguishing lime is poured into a barrel of water until completely immersed. After the appearance of soaring, more water is added and mixed. Extinguishing takes an average of 8 minutes.

2. Medium-extinguishing lime is poured into a container and filled with water in double volume. When steaming, water is also added and mixed. The process continues for approximately 25 minutes.

3. Slow-extinguishing lime is only moistened with water. The reaction is accompanied by a threefold increase in volume and an increase in temperature. Takes over 25 minutes.

The prepared material is diluted with water in a ratio of 1: 1 to the state of milk of lime. Often, for the final extinguishing, it is poured into a special pit, sprinkled with a layer of sand and earth and aged in this way for 15-20 days. The composition acquires a creamy consistency and is now called lime dough or paste.

For cement-lime plaster mortar, the most commonly used cement is:

• type I Portland cement with a minimum amount of additives and a high setting rate;
• Type II Portland cement grades M500-400 with additives up to 35%.

As practice shows, three-layer plastering is most often used at construction sites. The proportions of the solution (water-sand-lime-cement) in this case will depend on the layer of plaster.

• draft layer - spray - 2.2: 6.7: 1.5: 1;
• middle layer - soil - 2.8: 9: 2.2: 1;
• finishing layer - covering - 4:13.5:3:1.

For the preparation of masonry cement mortar, it is more expedient to use a concrete mixer, since in practice it is required more than plaster. The latter, in turn, is prepared in improvised containers using a construction mixer.

Part of the water is poured into the concrete mixer, then cement, lime and sand are alternately added in the required proportion. After thorough mixing, the mixture is closed with the remaining water.

In the case of manual preparation, there are two types of procedures:

1. The lime dough is passed through a sieve with a mesh diameter of not more than 3 mm. Then sand and cement are added in portions to it, everything is thoroughly mixed until the required fat content of the solution is obtained.

2. A dry mixture of sand and cement is prepared in the right ratio. Lime milk is gradually poured into it, if necessary, diluted with water to achieve the required consistency.

To increase the stability of the solution to environmental factors, slow down the hardening process, the following are added to the finished mixture:

• plasticizers;
• frost-resistant additives;
• setting retarders and others.

The Portland cement used in the composition also brings a number of positive characteristics to the material:

1. in combination with the action of hydraulic additives, it provides resistance to leaching, and therefore to long-term exposure to ground and sea waters;

2. gives cement a high level of anti-corrosion protection;

3. lime mixtures with Portland cement are not prone to destruction even with seasonal changes in freezing and thawing modes.