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Applies to all types of cellular concrete of autoclave and non-autoclave hardening, except for naturally hardening concrete, and establishes technical requirements to cellular concrete, materials for their production, as well as technological processes and methods for monitoring the technical characteristics of these concretes. The requirements of the standard must be observed when developing standards and technical specifications on products and structures made of cellular concrete, regulatory and technical, design and technological documentation, as well as in the manufacture of products from cellular concrete.

• Replaced by GOST 25485-89 “Cellular concrete. Technical specifications" IUS 8-1989

2. Technical requirements

3. Control and testing methods

Appendix 2 (informative) Names of the main types of cellular concrete

Appendix 3 (informative) List industry standards and technical specifications for materials for the preparation of cellular concrete

Organizations:

• GOST 11118-73Panels from autoclaved cellular concrete for external walls of buildings. Technical requirements . Replaced by GOST 11118-2009.
• GOST 12504-80Panels internal concrete and reinforced concrete walls for residential and public buildings. General technical conditions. Replaced by GOST 12504-2015.
• GOST 19570-74Panels from autoclaved cellular concrete for internal load-bearing walls, partitions and ceilings of residential and public buildings. Technical requirements . Replaced by GOST 19570-2018.
• GOST 3476-74Granulated blast furnace and electrothermophosphorus slags for cement production
• GOST 9179-77Construction lime. Specifications. Replaced by GOST 9179-2018.
• GOST 12730.1-78Concrete. Methods for determining density
• GOST 12852.5-77vapor permeability coefficient
• GOST 12852.6-77Cellular concrete. Determination method sorption humidity
• GOST 23732-79Water for concrete and mortars. Specifications. Replaced by GOST 23732-2011.
• GOST 4.212-80System of product quality indicators. Construction. Concrete. Nomenclature of indicators
• GOST 5742-76Heat-insulating products made from cellular concrete
• GOST 2263-79Technical caustic soda. Specifications
• GOST 3252-80Hide glue. Specifications
• GOST 4221-76Reagents. Potassium carbonate. Specifications
• GOST 10178-76Portland cement and Portland slag cement. Specifications
• GOST 12852.4-77Cellular concrete. Methods for determining frost resistance
• GOST 12852.3-77Cellular concrete. Method for determining drying shrinkage
• GOST 21520-76Small cellular concrete wall blocks
• GOST 8736-77Sand for construction work. Specifications

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CELLULAR CONCRETE

Price 5 kopecks.

Official publication

USSR STATE COMMITTEE FOR CONSTRUCTION AFFAIRS Moscow

Research Institute of Concrete and Reinforced Concrete (NIIZhB) of the USSR State Construction Committee

Central Research Institute building structures them. V. A. Kucherenko (TsNIISK) State Construction Committee of the USSR

Research Institute of Building Physics (NIISF) of the USSR State Construction Committee

Leningrad Zonal Research and Design Institute for Standard and Experimental Design of Residential and public buildings State Civil Engineering of the USSR

Ministry of Industry building materials USSR

PERFORMERS

T. A. Ukhova, Ph.D. tech. Sciences (topic leader); B. P. Filippov, Ph.D. tech. sciences; B. A. Novikov, Ph.D. tech. sciences; B. A. Usov, Ph.D. tech. sciences; N. I. Levin, Ph.D. tech. sciences; I. Ya. Kiselev, Ph.D. tech. sciences; V. A. Pinsker, Ph.D. tech. sciences; E. O. Nesley; L. I. Ostrat; I. I. Kostin

INTRODUCED by the Research Institute of Concrete and Reinforced Concrete (NIIZHB) of the USSR State Construction Committee

Deputy Director N. N. Korovin

APPROVED AND ENTERED INTO EFFECT by Resolution State Committee USSR for Construction Affairs dated August 9, 1982 No. 204

1. Panels made of autoclaved cellular concrete for external walls of buildings in accordance with GOST 11118-73.

2. Panels made of autoclaved cellular concrete for internal load-bearing walls, partitions and ceilings of residential and public buildings in accordance with GOST 19570-74.

3. Heat-insulating products made of cellular concrete in accordance with GOST 5742-76.

4. Small cellular concrete wall blocks according to GOST 21520-76.

5. Internal concrete and reinforced concrete wall panels for residential and public buildings in accordance with GOST 12504-80.

Note. Autoclaved cellular concrete can be used for the manufacture of the entire recommended range of products. Non-autoclaved cellular concrete is recommended for use in the manufacture of small wall blocks and thermal insulation products.

APPENDIX 2 Information

NAMES OF MAIN TYPES OF CELLULAR CONCRETE

Cellular concretes receive names that first reflect the type of pore-forming agent, the type of siliceous component and the main binder, and then the purpose and method of heat treatment.

The name does not reflect the method of heat treatment, if autoclave treatment is used, or the type of silica component - in the case of using finely ground sand and enrichment products of various ores.

When used as a binder, Portland cement or a mixed binder based on cement and lime, slag, or shale ash, the material is called “concrete.”

When using highly basic (shale) ash or slag as a binder, as well as a mixed binder based on them, the material is called “shale concrete” and “slag concrete,” respectively.

When used as a lime and lime-belite binder

The binder material is called “silicate”.
abbreviated name	Specified name
Structural concrete with cellular structure	Structural aerated concrete Structural foam concrete Structural gas silicate Structural foam silicate Structural gas-slag concrete Structural gas-slag concrete Structural foam-slag concrete Structural gas-ash concrete Structural gas-ash concrete Structural gas-ash-silicate structural Foam-ash-silicate Structural gas-ash-slag concrete Structural foam ash concrete Structural gas ash concrete non-autoclaved Structural foam ash concrete non-autoclaved Structural gas-slag-ash concrete, non-autoclave Structural non-autoclave foam slag concrete
Structural and thermal insulating concrete of cellular structure	Structural and thermal insulating aerated concrete Structural and thermal insulating foam concrete Structural and thermal insulating gas silicate Foam silicate structural and thermal insulation Gas-slag concrete, structural-thermal-volatile

	Continuation
abbreviated name	Specified name
Structural and thermal insulating concrete of cellular structure	Structural and thermal insulating gas-slate concrete Foam slag concrete for structural and thermal insulation Structural and thermal insulating foam shale concrete Gas-assisted concrete for structural and thermal insulation Foam ash concrete for structural and thermal insulation Gas-ash silicate for structural and thermal insulation Foam ash silica structural and thermal insulation material Gas-ash-slag concrete structural-heat-insulating Foam-ash-slag concrete structural and thermal insulation Gas-assisted concrete, structural and thermal insulation, autoclaved Foam ash concrete structural and thermal insulation non-autoclave Gas-slag and ash concrete, structural and thermal insulation, non-autoclave Foamed slag and ash concrete, structural and thermal insulation, non-autoclave
Heat-insulating concrete with cellular structure	Thermal insulating aerated concrete Thermal insulating foam concrete Thermal insulating gas silicate foam Silicate thermal insulation Thermal insulating gas slag concrete Thermal insulating foam slag concrete Thermal insulating gas slate concrete Thermal insulating foam slate concrete Thermal insulating gas ash concrete Thermal insulating foam ash concrete insulating Gas-assisted concrete heat-insulating non-autoclave Heat-insulating non-autoclave foam ash concrete Gas-slag-ash concrete heat-insulating nsav-toclave Heat-insulating non-autoclave foam slag concrete

APPENDIX 3 Information

SCROLL

for materials for the preparation of cellular concrete

industry standards and specifications

Editor V. P. Ogurtsov Technical editor V. N. Prusakova Corrector A. G. Starostin

Delivered to embankment 04.11.82 Podl, to the stove. 11/30/82 1.0 p.l. 0.S3 academic ed. l. Shooting gallery 25000 Price 5 kopecks%

Order "Badge of Honor" Publishing house of standards, 123557. Moscow. Novopresnensky lane, 3 Type. "Moscow Printer". Moscow, Ldoin lane, 6. Zak. 1230

Price 5 kopecks.

BASIC SI UNITS

kilogram Electric current strength Thermodynamic temperature Quantity of substance The power of light SI UNITS Flat angle Solid angle steradian

DERIVATIVE SI UNITS WITH SPECIAL NAMES

				Itpei expression OOIIY1I ■ before- oolzheanmye
	Naisioaa*
				passed SI
Pressure				M"" kg C"*
Power
Amount of electricity
Electrical voltage				m? kg s" 5 A""
Electrical capacity				m“* kg‘ s 4 * A*
Electrical resistance				m* kg s"* A"*
Electrical conductivity				I-" KG- s’ A’
Magnetic induction flux				m" kg s“* A""
Magnetic induction				kg s* 9 A"’
Inductance				m* kg s" 5 A"* 5
Light flow
Illumination				m-g CD Wed
Radionuclide activity	becquerel
Absorbed fraction of ionizing radiation
Equivalent radiation dose

UDC 666.173.6: 006.354 Group Zh13

STATE STANDARD OF THE USSR UNION

CELLULAR CONCRETE Technical specifications

Cellular concretes. Specifications

GOST

25485-82

By Decree of the USSR State Committee for Construction Affairs dated August 9, 1982 No. 204, the introduction date was established

Failure to comply with the standard is punishable by law

This standard applies to all types of autoclaved and non-autoclaved cellular concrete, except for naturally hardening concrete, and establishes technical requirements for cellular concrete, materials for their production, as well as for technological processes and methods for monitoring the technical characteristics of these concretes.

The requirements of this standard must be observed when developing standards and technical specifications for products and structures (hereinafter referred to as products) made of cellular concrete, regulatory, technical, design and technological documentation, as well as in the manufacture of products from cellular concrete.

1. types

1.1. Cellular concrete, which is subject to the requirements of the standard, is divided into:

hardening conditions;

type of blowing agent;

types of binders and siliceous components used.

1.2. According to the hardening conditions, cellular concrete can be:

autoclaved, hardening in saturated water vapor

under pressure above atmospheric;

non-autoclave, hardening in an environment of saturated water vapor or during electrical heating at atmospheric pressure;

Official publication

1.3. Based on the type of pore-forming agent, cellular concretes are divided into:

Reproduction is prohibited

©Standards Publishing House, 1982

GOST 25485-82

aerated concrete;

foam concrete.

1.4. Depending on the type of binders used, cellular concrete can be based on:

cement binders in which the Portland cement content is more than 50%;

lime binders, consisting of lime-lime (in an amount of more than 50%) in combination with or without slag, gypsum;

slag binders, consisting of slag (more than 50%) in combination with lime, gypsum or alkali;

highly basic ash, in which the ash content is more than 50%;

mixed binders consisting of Portland cement (in an amount of 50% or less) in combination with lime or slag.

1.5. Based on the type of silica component, cellular concrete can be:

natural (finely ground quartz and feldspathic sands); siliceous secondary products of industry (fly ash from thermal power plants, secondary products from the enrichment of various ores).

1.6. Depending on the main purpose, cellular concrete is divided into:

thermal insulation;

structural and thermal insulation;

structural;

special (heat-resistant, soundproof, etc.).

1.7. The names of cellular concrete must comply with GOST 25192-82 with the addition of the following specific features: the type of blowing agent used, the silica component and the method of heat treatment.

Examples of the names of cellular concrete are given in help app 2.

2. TECHNICAL REQUIREMENTS

2.1. Cellular concrete

2.M. Quality cellular concrete must meet the requirements of this standard and ensure the manufacture of products that meet the requirements state standards and technical specifications for these products.

2.1.2. Depending on the guaranteed compressive strength values ​​of concrete in accordance with ST SEV 1406-78, the following classes are established: VO,35; VO,75; VO,85; IN 1; B 1.5; B2.5; B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15; B17.5; IN 20.

Note. For products made of cellular concrete, designed without taking into account the requirements of ST SEV 1406-78, compressive strength indicators are characterized by the following grades: M5; M10; M15; M25; M35; M50; M75; Ml00; M150; M200;

2.1.3. By indicators medium density(volumetric mass) and frost resistance, the following grades of cellular concrete are established:

by average density (volumetric mass) - PlZOO, Pl400, PlbOO, PlbOO, Pl700, Pl800, Pl900, PlyuOO, Pl1100, Pl1200;

in terms of frost resistance - Mrz 15, Mrz25, MrzZb, Mrz50, Mrz75, Mrz 100.

2.1.4. Indicators of the basic physical and technical properties (average density, strength, frost resistance, drying shrinkage, thermal conductivity, vapor permeability and sorption humidity) of cellular concrete must meet the requirements of state standards and technical specifications for individual species products, as well as the data given in table. 1 and 3 for autoclaved concrete and in table. 2 and 3 - for non-autoclaved concrete.

Table 1

Type of concrete Compressive strength class Thermal insulation- MrzZb; Mrz25; Mrz 15 Mrz25; Mrz 15 Construction Mrz75; Mrz50; Mrz35; Mrz25; on-thermal insulation lational Mrz35; Mrz25; Mrz 15 Mrz25; Mrz 15 Mrz 100; Mrz75; Mrz50; Mrz35; Mrz25; Mrz 15 Mrz75; Mrz50; Mrz35; Mrz25; Mrz35; Mrz25 Mrz 100; Mrz75; Mrz50; Mrz35; Mrz25; Mrz 15 Mrz75; Mrz50; Mrz35; Mrz25; Mrz35; Mrz25; Mrz 15 Mrz75; Mrz50; Mrz35; Mrz25; Mrz50; Mrz35; Mrz25; Mrz 15 Mrz35; Mrz25; Mrz 15

GOST 25485-82

Continuation of the table. 1

Type of concrete Concrete grade by average density Concrete grade by strength under axial compression Compressive strength class Concrete grade for frost resistance Construction Mrz50; Mrz35; Mrz25; Mrz15 Mrz35; Mrz25; Mrz15 Mrz25 Mrz50; Mrz35; Mrz25; Mrz15 Mrz35; Mrz25; Mrz15 Mrz25; Mrz15 Mrz50; Mrz35; Mrz25; Mrz15 Mrz35; Mrz25; Mrz15 Mrz25; Mrz15

Note. The amount of shrinkage during drying of autoclaved cellular concrete with an average density of PlZOO-Pl400 is not standardized, but with an average density of Pl500-Pl1200 it should be no more than 0.7 mm/m for cellular concrete on ash and 0.5 mm/m for cellular concrete concrete on sand and secondary products of enrichment of various ores.

table 2

Concrete grade according to Type of concrete on average strength strength Concrete grade for frost resistance DENSITY with axial for compression Thermal insulation Construction Mrz25; Mrz15 onno-heat- insulating Mrz35; Mrz25; Mrz 15 Mrz25; Mrz 15 Mrz35; Mrz25; Mrz15 Mrz25; Mrz 15 Mrz35; Mrz25; Mre15 Mrz25; Mrz 15

Continuation of the table. 2

Type of concrete Concrete grade by average density Concrete grade by strength under axial compression Compressive strength class Concrete grade for frost resistance Construct Mrz35; Mrz25; Mrz15 Mrz25; Mrz 15 Mrz35; Mrz25; Mrz 15 Mrz25; Mrz 15 Mrz35; Mrz25; Mrz 15 Mrz25; Mrz 15

Note. After heat and moisture treatment, non-autoclaved cellular concrete must have a compressive strength of at least 70% of the branded one.

The amount of shrinkage during drying of non-autoclaved cellular concrete with an average density of Pl300-t-Pl500 is not standardized, but with an average density of Pl600-^Pl1200 it should be no more than 3 mm/m.

Table 3

Type of concrete Concrete grade by average density Thermal conductivity coefficient, kcal/m -s-°C, no more, in the dry state of concrete made Vapor permeability coefficient, r/m-h, not less, of concrete made Sorptive humidity (at relative humidity air 76x), x. no more than concrete made insulating Design- thermal insulation manual

2.1.5. Depending on the operating conditions and type of products, standards or technical conditions for specific types of products may establish other concrete quality indicators provided for by GOST 4.212-80.

2.1.6. The stability of indicators for density and compressive strength of autoclaved cellular concrete should be characterized by coefficients of variation.

The batch coefficients of variation are shown in Table. 4.

2.2. Materials

2.2.1. Materials for the preparation of cellular concrete must meet the requirements of current standards, technical specifications for these materials and ensure that concrete obtains the specified technical characteristics.

2.2.2. For the preparation of cellular concrete they use the following types binders:

highly basic ash binder (from oil shale combustion);

lime-belite binder.

2.2.3. The following is used as a siliceous component: quartz sand according to GOST 8736-77;

finely ground feldspathic sand; acidic fly ash from thermal power plants;

finely dispersed secondary products of ore enrichment.

2.2.4. Water for preparing cellular concrete must meet the requirements of GOST 23732-79.

2.2.5. The following pore formers are used: gas former - aluminum powder grade PAP-1 according to

foam concentrates based on:

for the production of products made from cellular concrete”, approved in in the prescribed manner.

3. CONTROL AND TEST METHODS

3.1. Materials for the preparation of cellular concrete must be tested in accordance with the requirements established by the standards for their testing methods.

3.2. Specifications cellular concrete is determined in accordance with the requirements of the following state standards:

average density ( volumetric mass) - according to GOST 12730.1-78 l “Instructions for the manufacture of products from cellular concrete”; shrinkage upon drying - according to GOST 12852.3-77; frost resistance - according to GOST 12852.4-77; vapor permeability - according to GOST 12852.5-77; sorption humidity - according to GOST 12852.6-77; thermal conductivity - according to GOST 7076-78.

CELLULAR CONCRETE

TECHNICAL CONDITIONS

GOST 25485-89

STATE CONSTRUCTION COMMITTEE OF THE USSR

1. Technical requirements

2. Acceptance

3. Control methods

4. Transportation and storage

Annex 1

Appendix 2

Appendix 3

Appendix 4

Appendix 5

STATE STANDARD OF THE USSR UNION

Date of introduction 01.01.90

Failure to comply with the standard is punishable by law

This standard applies to cellular concrete (hereinafter referred to as concrete).

The requirements of this standard must be observed when developing new and revising existing standards and technical specifications, design and technological documentation for products and structures made from these concretes, as well as during their manufacture.

1. TECHNICAL REQUIREMENTS

1.1. Concrete must meet the requirements of GOST 25192 and they should be manufactured in accordance with the requirements of this standard according to technological documentation approved in the prescribed manner.

1.2. Main settings

1.2.1. Concrete is divided into:

by appointment;

according to hardening conditions;

by the method of pore formation;

by types of binders and siliceous components.

1.2.2. According to their intended purpose, concrete is divided into:

structural;

structural and thermal insulation;

thermal insulation.

1.2.3. According to hardening conditions, concrete is divided into:

autoclave (synthetic hardening) - hardening in a saturated steam environment at a pressure above atmospheric;

non-autoclave (hydration hardening) - hardening in natural conditions, during electrical heating or in a saturated steam environment at atmospheric pressure.

1.2.4. Based on the method of pore formation, concrete is divided into:

for aerated concrete;

for foam concrete;

for gas foam concrete.

1.2.5. Based on the type of binder and siliceous components, concretes are divided into:

by type of main binder:

on lime binders consisting of lime-lime more than 50% by weight, slag and gypsum or cement additives up to 15% by weight;

on cement binders in which the Portland cement content is 50% or more by weight;

on mixed binders consisting of Portland cement from 15 to 50% by weight, lime or slag, or slag-lime mixture;

on slag binders, consisting of slag more than 50% by weight in combination with lime, gypsum or alkali;

on ash binders, in which the content of highly basic ash is 50% or more by weight;

by type of silica component:

on natural materials - finely ground quartz and other sands;

on secondary industrial products - fly ash from thermal power plants, hydraulic removal ash, secondary products from the enrichment of various ores, ferroalloy waste and others.

1.2.6. The names of concretes must include both basic and specific characteristics: purpose, hardening conditions, method of pore formation, type of binder and siliceous components.

1.3.Characteristics

1.3.1. The strength of autoclaved and non-autoclaved concrete is characterized by classes of compressive strength in accordance with ST SEV 1406.

The following classes are established for concrete: B0.5; B0.75; IN 1; B1.5; AT 2; B2.5; B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15.

For structures designed without taking into account the requirements of ST SEV 1406, the compressive strength of concrete is characterized by the following grades: M7.5; M10; M15; M25; M35; M50; M75; M100; M150; M200.

1.3.2. Based on average density indicators, the following grades of concrete in a dry state are prescribed: D300; D350; D400; D500; D600; D700; D800; D900; D1000; D1100; D1200.

1.3.3. For concrete structures subject to alternating freezing and thawing, the following grades of concrete are assigned and controlled for frost resistance: F15; F25; F35; F50; F75;F100.

The assignment of a concrete grade for frost resistance is carried out depending on the operating mode of the structure and design winter temperatures outdoor air in construction areas.

1.3.4. Indicators of physical and mechanical properties of concrete are given in table. 1.

Table 1

Indicators of physical and mechanical properties of concrete

Type of concrete	Concrete grade by average density	Autoclaved concrete		Non-autoclaved concrete
		compressive strength class	frost resistance grade	Compressive strength class	Frost resistance grade
Thermal insulation			Not standardized
					Not standardized
Structural thermal insulation			From F15 to F35
			From F15 to F75		From F15 to F35
			From F15 to F100		From F15 to F50
					From F15 to F75
			From F15 to F75
Structural			From F15 to F50		From F15 to F50

1.3.5. Shrinkage during drying of concrete, determined according to Appendix 2, should not exceed, mm/m:

0.5 - for autoclaved concrete grades D600-D1200 made on sand;

0.7 - the same, on other siliceous components;

3.0 - for non-autoclaved concrete grades D600-D1200.

Note: For autoclaved concrete of average density grades D300, D350 and D400 and non-autoclaved concrete of average density D400 and D500, drying shrinkage is not standardized.

1.3.6. The thermal conductivity coefficients of concrete should not exceed the values ​​given in table. 2 by more than 20%.

table 2

Standardized indicators of physical and technical properties of concrete

Type of concrete	Concrete grade by average density	Coefficient				Sorptive humidity of concrete, % no more
		thermal conductivity, W/(m С), no more than, concrete in a dry state, prepared		vapor permeability, mg/(m  h  Pa), not less, of concrete, manufactured		at a relative air humidity of 75%		at a relative air humidity of 97%
						Concrete made
			on ash	on sand	on ash	on sand	on ash	on sand	on ash
Thermal insulation
Structural and thermal insulation
Structural

Note. For concrete grade of average density D350, the normalized indicators are determined by interpolation.

1.3.7. The release moisture content of concrete products and structures should not exceed (by weight),%:

25 - sand-based;

35 - based on ashes and other production waste.

1.3.8. In standards or technical specifications for structures specific types establish the indicators of sorption humidity and vapor permeability given in table. 2, and other indicators provided for by GOST 4.212.

In addition, when studying new properties of concrete and for the data necessary for normalizing the design characteristics of concrete, the quality of concrete is characterized by prismatic strength, elastic modulus, and tensile strength.

1.3.9. Materials

1.3.9.1. Binders used for concrete:

Portland cement - according to GOST 10178 (does not contain additives of tripoli, gliezh, routes, clay, flask, ash), containing tricalcium aluminate (C 3 A) no more than 6% for the manufacture of large-sized structures using cement or mixed binder;

quicklime calcium - according to GOST 9179, quickly and moderately slaking, having a slaking speed of 5 - 25 minutes and containing active CaO + MgO more than 70%, “overburning” less than 2%;

granulated blast furnace slag - according to GOST 3476;

highly basic ash - according to OST 21-60, containing CaO of at least 40%, including free CaO of at least 16%, SO 3 - no more than 6% and R 2 O - no more than 3.5%.

1.3.9.2. Siliceous components used for concrete:

sand - according to GOST 8736, containing SiO 2 (total) no less than 90% or quartz no less than 75%, mica no more than 0.5%, silt and clay impurities no more than 3%;

fly ash from thermal power plants - according to OST 21-60, containing SiO 2 not less than 45%, CaO - not more than 10%, R 2 O - not more than 3%, SO 3 - not more than 3%;

ore beneficiation products containing SiO 2 of at least 60%.

1.3.9.3. The specific surface area of ​​the materials used is taken according to the technological documentation, depending on the required average density, heat and moisture treatment and dimensions of the structure.

1.3.9.4. It is allowed to use other materials that ensure the production of concrete that meets the specified physical and technical characteristics established by this standard.

1.3.9.5. Blowing agents used for concrete:

gas-forming agent - aluminum powder of grades PAP-1 and PAP-2 - according to GOST 5494;

foaming agent based on:

bone glue - according to GOST 2067;

hide glue - according to GOST 3252;

pine rosin - according to GOST 19113;

technical caustic soda - according to GOST 2263;

scrubber paste - according to TU 38-107101 and other foaming agents.

1.3.9.6. Regulators of structure formation, increase in plastic strength, hardening accelerators and plasticizing additives:

gypsum and gypsum anhydrite stone - according to GOST 4013;

potassium carbonate - according to GOST 4221;

technical soda ash - according to GOST 5100;

liquid sodium glass - according to GOST 13078;

triethanolamine - according to TU 6-09-2448;

trisodium phosphate - according to GOST 201;

superplasticizer S-3 - according to TU 6-14-625;

technical caustic soda - according to GOST 2263;

carboxylmethylcellulose - according to OST 6-05-386;

crystallization sodium sulfate - according to GOST 21458 and other additives.

1.3.9.7. Water for preparing concrete - according to GOST 23732.

1.3.9.8. Selection of concrete compositions - in accordance with GOST 27006, methods, manuals and recommendations of research institutes, approved in the prescribed manner.

1.4. Labeling and packaging

Marking and packaging of products and structures made of concrete are carried out in accordance with the requirements of standards or technical specifications for products and structures of specific types.

2. ACCEPTANCE

2.1. Acceptance of concrete products and structures - in accordance with GOST 13015.1 and standards or technical specifications for specific types of structures.

2.2. Acceptance of concrete for strength, average density and release moisture content is carried out for each batch of products.

2.3. Control of concrete in terms of frost resistance, thermal conductivity and drying shrinkage is carried out before the start of mass production, when changing technology and materials, while in terms of frost resistance and drying shrinkage at least once every 6 months and in terms of thermal conductivity - at least once a year .

2.4. Concrete control in terms of sorption humidity, vapor permeability, prismatic strength, elastic modulus is carried out according to standards or technical specifications for products and structures of specific types.

2.5. Concrete strength control is carried out according to GOST 18105, medium density - according to GOST 27005.

3. CONTROL METHODS

Physical and technical indicators are monitored by:

compressive and tensile strength - according to GOST 10180;

average density - according to GOST 12730.1 or GOST 17623;

release humidity - according to GOST 12730.2, GOST 21718;

frost resistance - according to Appendix 3;

shrinkage upon drying - according to Appendix 2;

thermal conductivity - according to GOST 7076, sampling - according to GOST 10180;

sorption humidity - according to GOST 24816 and GOST 17177;

vapor permeability - according to GOST 25898;

prismatic strength - according to GOST 24452;

elastic modulus - according to GOST 24452 and (or) Appendix 5.

4. TRANSPORTATION AND STORAGE

Transportation and storage of concrete structures is carried out in accordance with the requirements of standards or technical specifications for products and structures of specific types.

ANNEX 1

1. External concrete and reinforced concrete wall panels for residential and public buildings - in accordance with GOST 11024.

2. Panels made of autoclaved cellular concrete for internal load-bearing walls, partitions and ceilings of residential and public buildings - according to GOST 19570.

3. Heat-insulating products made from cellular concrete - according to GOST 5742.

4. Small blocks of cellular concrete for walls - according to GOST 21520.

5. Internal concrete and reinforced concrete wall panels for residential and public buildings - according to GOST 12504.

6. Panels made of autoclaved cellular concrete for external walls of buildings - according to GOST 11118.

Note. Autoclaved concrete is used for the manufacture of the entire recommended range of products and structures, non-autoclave concrete is used mainly for the manufacture of small wall blocks and thermal insulation.

APPENDIX 2

Mandatory

METHOD FOR DETERMINING DRYING SHRINKAGE

INTERSTATE STANDARD

CELLULAR CONCRETE

TECHNICAL CONDITIONS

Official publication

IPC PUBLISHING HOUSE OF STANDARDS

UDC 666.973.6:006.354

Group Zh13

INTERSTATE STANDARD

CELLULAR CONCRETE

Technical specifications GOST

Cellular concretes.

MKS 91.100.30 OKP 58 7000

Date of introduction 01/01/90

This standard applies to cellular concrete (hereinafter referred to as concrete).

The requirements of this standard should be observed when developing new and revising existing standards and technical specifications, design and technological documentation for products and structures made from these concretes, as well as during their manufacture.

1. TECHNICAL REQUIREMENTS

1.1. Concrete must meet the requirements of GOST 25192, they should be manufactured in accordance with the requirements of this standard according to technological documentation approved in the prescribed manner.

1.2. Main settings

1.2.1. Concrete is divided according to:

Purpose;

Hardening conditions;

Method of pore formation;

Types of binders and siliceous components.

1.2.2. According to their intended purpose, concrete is divided into:

Structural;

Structural and thermal insulation;

Thermal insulation.

1.2.3. According to hardening conditions, concrete is divided into:

Autoclave (synthetic hardening) - hardening in a saturated steam environment at a pressure above atmospheric;

Non-autoclave (hydration hardening) - hardening under natural conditions, during electrical heating or in an environment of saturated steam at atmospheric pressure.

1.2.4. According to the method of pore formation, concretes are divided into:

Aerated concrete;

Foam concrete;

Gas foam concrete.

1.2.5. Based on the type of binder and siliceous components, concretes are divided into:

According to the type of main binder:

on lime binders consisting of lime-lime more than 50% by weight, slag and gypsum or cement additives up to 15% by weight,

on cement binders in which the Portland cement content is 50% or more by weight,

on mixed binders consisting of Portland cement from 15% to 50% by weight, lime or slag, or slag-lime mixture,

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© Standards Publishing House, 1989 © IPK Standards Publishing House, 2003

on slag binders consisting of slag more than 50% by weight in combination with lime, gypsum or alkali,

on ash binders, in which the content of highly basic ash is 50% or more by weight;

By type of silica component:

on natural materials- finely ground quartz and other sands,

on secondary industrial products - fly ash from thermal power plants, hydraulic removal ash, secondary products from the enrichment of various ores, waste ferroalloys and others.

1.2.6. The names of concretes must include both basic and specific characteristics: purpose, hardening conditions, method of pore formation, type of binder and siliceous components.

1.3. Characteristics

1.3.1. The strength of autoclaved and non-autoclaved concrete is characterized by classes of compressive strength in accordance with ST SEV 1406.

The following classes are established for concrete: VO,5; VO,75; Bl; Bl,5; AT 2; B2.5; B3.5; AT 5; B7.5; BIO; B12.5; B15.

For structures designed without taking into account the requirements of ST SEV 1406, the compressive strength of concrete is characterized by the following grades: M7.5; M10; M15; M25; M35; M50; M75; M100; Ml50; M200.

1.3.2. Based on average density indicators, the following grades of concrete in a dry state are prescribed: D300; D350; D400; D500; D600; D700; D800; D900; D1000; D1100; D1200.

1.3.3. For concrete structures subject to alternating freezing and thawing, the following grades of concrete are assigned and controlled for frost resistance: F15; F25; F35; F50; F75; F100.

The assignment of a concrete grade for frost resistance is carried out depending on the operating mode of the structure and the calculated winter temperatures of the outside air in the construction areas.

1.3.4. Indicators of physical and mechanical properties of concrete are given in table. 1.

Indicators of physical and mechanical properties of concrete

Table 1

Type of concrete		Autoclaved concrete		Non-autoclaved concrete
		Compressive strength class	Frost resistance grade	Compressive strength class	Frost resistance grade
Thermal insulation-		VO,75 VO,50	Not standardized
					Not standardized
Construction on-thermal insulation lational			From F15 to F35
			From F15 to F75		From F15 to F35
			From F15 to F100		From F15 to F50
					From F15 to F75

1.3.5. Shrinkage during drying of concrete, determined according to Appendix 2, should not exceed, mm/m:

0.5 - for autoclaved concrete grades D600-D1200 made on sand;

0.7 - the same, on other siliceous components;

3.0 - for non-autoclaved concrete grades D600-D1200.

Note. For autoclaved concrete of average density grades D300, D350 and D400 and non-autoclaved concrete of average density D400 and D500, drying shrinkage is not standardized.

1.3.6. The thermal conductivity of concrete should not exceed the values ​​given in table. 2, more than 20%.

Standardized indicators of physical and technical properties of concrete

table 2

Type of concrete	Concrete grade by average density	Thermal conductivity, W/(m-C), no more, of concrete in a dry state, manufactured		Vapor permeability coefficient, mgDm h-Pa), not less, of concrete made		Sorptive humidity of concrete, %, no more
						at a relative air humidity of 75%		at a relative air humidity of 97%
						Concrete made
but-warm-

Note. For concrete grade of average density D350, the standardized indicators are determined

interpolation.

1.3.7. The release moisture content of concrete products and structures should not exceed (by weight), %:

25 - sand-based;

35 - based on ashes and other production waste.

1.3.8. In standards or technical specifications for specific types of structures, the indicators of sorption humidity and vapor permeability given in table are established. 2, and other indicators provided for by GOST 4.212.

In addition, when studying new properties of concrete and for the data necessary for normalizing the design characteristics of concrete, the quality of concrete is characterized by prismatic strength, elastic modulus, and tensile strength.

1.3.9. Materials

1.3.9.1. Binders used for concrete:

Portland cement according to GOST 10178 (does not contain additives of tripoli, gliezh, traces, clayite, opoka, ash), containing tricalcium aluminate (C 3 A) no more than 6% for the manufacture of large-sized structures using cement or mixed binder;

Quicklime calcium in accordance with GOST 9179, fast- and medium-slaking, having a slaking speed of 5-25 minutes and containing active CaO + MgO more than 70%, “overburning” less than 2%;

Granulated blast furnace slag according to GOST 3476;

Highly basic ash according to OST 21-60, containing CaO not less than 40%, including free CaO not less than 16%, S0 3 not more than 6% and R 2 0 not more than 3.5%.

1.3.9.2. Siliceous components used for concrete:

Sand according to GOST 8736, containing Si0 2 (total) no less than 90% or quartz no less than 75%, mica no more than 0.5%, silt and clay impurities no more than 3%;

Fly ash from thermal power plants according to OST 21-60, containing Si0 2 not less than 45%, CaO not more than 10%, R 2 0 not more than 3%, S0 3 not more than 3%;

Ore enrichment products containing Si0 2 of at least 60%.

1.3.9.3. The specific surface area of ​​the materials used is taken according to the technological documentation, depending on the required average density, heat and moisture treatment and dimensions of the structure.

1.3.9.4. It is allowed to use other materials that ensure the production of concrete that meets the specified physical and technical characteristics established by this standard.

1.3.9.5. Blowing agents used for concrete:

Gas-forming agent - aluminum powder of grades PAP-1 and PAP-2 according to GOST 5494;

Foaming agent based on: bone glue in accordance with GOST 2067, hide glue in accordance with GOST 3252, pine rosin in accordance with GOST 19113, caustic soda in accordance with GOST 2263,

scrubber paste according to TU 38-107101 and other foaming agents.

1.3.9.6. Regulators of structure formation, increase in plastic strength, hardening accelerators and plasticizing additives:

Gypsum and gypsum anhydrite stone according to GOST 4013;

Potassium carbonate according to GOST 4221;

Technical soda ash according to GOST 5100;

Liquid sodium glass according to GOST 13078;

Triethanolamine according to TU 6-09-2448;

Trisodium phosphate according to GOST 201;

Superplasticizer S-3 according to TU 6-14-625;

Technical caustic soda according to GOST 2263;

Carboxylmethylcellulose according to OST 6-05-386;

Sodium sulfate crystallization according to GOST 21458 and other additives.

1.3.9.7. Water for preparing concrete - according to GOST 23732.

1.3.9.8. Selection of concrete compositions - in accordance with GOST 27006, methods, manuals and recommendations of research institutes, approved in the prescribed manner.

1.4. Labeling and packaging

Marking and packaging of products and structures made of concrete are carried out in accordance with the requirements of standards or technical specifications for products and structures of specific types.

2. ACCEPTANCE

2.1. Acceptance of concrete products and structures - in accordance with GOST 13015.1 and standards or technical specifications for specific types of structures.

2.2. Acceptance of concrete for strength, average density and release moisture content is carried out for each batch of products.

2.3. Control of concrete in terms of frost resistance, thermal conductivity and drying shrinkage is carried out before the start of mass production, when technology and materials change, while in terms of frost resistance and drying shrinkage - at least once every 6 months and in terms of thermal conductivity - at least once every year.

2.4. Concrete control in terms of sorption humidity, vapor permeability, prismatic strength, elastic modulus is carried out according to standards or technical specifications for products and structures of specific types.

2.5. Concrete strength control is carried out according to GOST 18105, medium density - according to GOST 27005.

3. CONTROL METHODS

Physical and technical indicators are monitored by:

Compressive and tensile strength - according to GOST 10180;

Average density - according to GOST 12730.1 or GOST 17623;

Release humidity - according to GOST 12730.2, GOST 21718;

Frost resistance - according to Appendix 3;

Drying shrinkage - according to Appendix 2;

Thermal conductivity - according to GOST 7076, sampling - according to GOST 10180;

Sorptive humidity - according to GOST 24816 and GOST 17177;

Vapor permeability - according to GOST 25898;

Prismatic strength - according to GOST 24452;

Elastic modulus - according to GOST 24452 and (or) Appendix 5.

4. TRANSPORTATION AND STORAGE

Transportation and storage of concrete structures is carried out in accordance with the requirements of standards or technical specifications for products and structures of specific types.

2. Panels made of autoclaved cellular concrete for internal load-bearing walls, partitions and ceilings of residential and public buildings in accordance with GOST 19570.

3. Heat-insulating products made of cellular concrete in accordance with GOST 5742.

4. Small cellular concrete wall blocks according to GOST 21520.

5. Internal concrete and reinforced concrete wall panels for residential and public buildings in accordance with GOST 12504.

6. Panels made of autoclaved cellular concrete for external walls of buildings in accordance with GOST 11118.

Note. Autoclave concretes are used for the manufacture of the entire recommended range of products and structures, non-autoclave concretes are used mainly for the manufacture of small wall blocks and thermal insulation.

APPENDIX 2 Mandatory

METHOD FOR DETERMINING DRYING SHRINKAGE

The essence of the method is to determine the change in the length of a concrete sample (in millimeters) when its moisture content changes from 35% to 5% by weight.

1. Preparation and selection of samples

1.1. The drying shrinkage of concrete is determined by testing a series of three prism samples measuring 40 x 40 x 160 mm.

1.2. Series samples are cut from a structure or from an unreinforced control block, the length and width of which must be at least 40 cm, the height is equal to the height of the structure, made simultaneously with the structure from its middle part so that the end faces of the samples are parallel to its filling, and the distance to edges of the structure - at least 10 cm.

1.3. Samples from the structure are cut out no later than 24 hours after the end of the heat and humidity treatment and are stored in closed desiccators above water until testing.

1.4. Deviations of the linear dimensions of the samples from the nominal ones specified in i. 1.1, - within ± 1 mm.

2. Requirements for control methods

For testing use:

A tripod with a dial indicator with a division value of 0.01 mm and a rod stroke of 10 mm, shown in Fig. 1;

Technical scales according to GOST 24104;

Laboratory drying cabinet type SNOL;

Desiccator according to GOST 25336;

Bath with lid;

Anhydrous potassium carbonate according to GOST 4221.

3. Preparation for testing

3.1. In the center of each end face of the sample, a reference point is strengthened with quickly polymerizing glue. of stainless steel, for this purpose a square plate with a thickness of at least 1 mm with ribs of at least 10 mm and a hole with a diameter of 1.5 mm in the center is used.

It is allowed to use glue of the following composition, g:

Epoxy resin...................80

Polyethylene and oliamine...................3

Dibutyl phthalate........................1

3.2. Before testing, measure the length of the samples and weigh them.

The sample measurement error is in accordance with GOST 10180.

4. Testing

4.1. Samples are saturated with water by immersing them in a horizontal position in water at a temperature of (20 ± 2) °C for 3 days to a depth of 5-10 mm.

4.2. After saturation, the samples are kept in a tightly closed desiccator over water at a temperature of (20 ± 2) °C for 3 days.

4.3. Immediately after removal from the desiccator, the samples are weighed and an initial reading is made using the indicator.

The error in weighing samples should be ±0.1 g, the error in determining changes in sample length is ±0.005 mm.

4.4. A series of samples are placed in a tightly closed desiccator positioned over anhydrous potassium carbonate. For a series of samples, every 7 days of testing, take (600 ± 10) g of potassium carbonate. Every 7 days, wet potassium carbonate is replaced with dry one.

Diagram of a tripod with a dial indicator

1 - base; 2 - stand; 3 - bracket; 4 - indicator; 5 - ball joint

4.5. The temperature of the room in which samples are tested must be (20 ± 2) °C.

4.6. During the first four weeks, changes in the length and weight of the samples are determined every 3-4 days. Subsequently, measurements are carried out at least once a week until the samples reach a constant mass.

The mass of samples is considered constant if the results of two consecutive weighings carried out at an interval of one week differ by no more than 0.1%.

4.7. After completing the shrinkage measurement, the samples are dried at a temperature of (105 ± 5) °C to constant weight and weighed.

5. Processing of results

5.1. For each sample calculate:

Drying shrinkage value (g), mm/m, after each measurement according to the formula

where / 0 is the initial reading on the indicator after water saturation of the sample, mm,

C - indicator reading after i day of holding the sample in a desiccator over potassium carbonate, mm,

L - sample length, m;

Concrete moisture content (by mass) (w), %, after completion of the test for the measurement period according to the formula

where nij is the mass of the wet sample after i day of exposure in a desiccator over potassium carbonate, g, t (] is the mass of the sample dried at a temperature of (105 + 5) °C, g.

5.2. Based on the values ​​of e (and w), a shrinkage curve is constructed for each sample. An approximate shrinkage curve is shown in Figure 2.

5.3. Damn it. 2 determine the shrinkage when the sample dries from humidity (e 0), mm/m, in the range from 35% to 5% by weight according to the formula

e 0 = e 5 - e 35, (3)

where e 5 is the value of shrinkage when the sample dries from its water-saturated state to a humidity of 5% by weight, mm/m;

e 35 - shrinkage value when the sample dries from a water-saturated state to a humidity of 35% by weight, mm/m.

5.4. The control value of drying shrinkage gk for the tested concrete is determined as the arithmetic mean e 0 of three tested samples.

5.5. Concrete meets the requirements if the control value of drying shrinkage gk does not exceed the standardized value accepted according to clause 1.3.5 of this standard, and the shrinkage value of individual samples is 1.25 e„.

5.6. The results of determining and monitoring drying shrinkage must be recorded in the test log.

The log states:

Batch number, date of manufacture, dimensions and weight of samples;

The date and results of each determination of changes in the length and weight of the samples;

Date and results of moisture calculation for each sample;

Conclusion based on the results of concrete shrinkage tests.

Approximate shrinkage curve when drying concrete samples

О 5 10 20 30 35 40 50 w f %

APPENDIX 3 Mandatory

METHOD FOR CONTROL OF FROST RESISTANCE OF CONCRETE

1. General Provisions

1.1. This method applies to structural and structural-thermal-insulating concrete.

1.2. Frost resistance of concrete is the ability to maintain physical and mechanical properties under repeated exposure to alternating freezing and thawing in air above water.

The frost resistance of concrete is characterized by its frost resistance grade.

1.3. The frost resistance grade of concrete F is taken to be the established number of cycles of alternating freezing and thawing according to the method of this appendix, in which the compressive strength of concrete is reduced by no more than 15% and the weight loss of concrete samples is reduced by no more than 5%.

2. Requirements for controls

2.1. To control frost resistance, use:

Freezer according to GOST 10060.0;

A chamber for thawing samples, equipped with a device for maintaining relative humidity (95 + 2)% and temperature (18 + 2) °C;

Bath for saturating samples;

Mesh racks in the freezer;

Mesh containers for placing samples.

2.2. To control the frost resistance of concrete, cameras with automatic regulation temperature and humidity, ensuring the ability to maintain the temperature and humidity specified in and. 2.1.

3. Preparation for testing

3.1. Frost resistance tests of concrete are carried out when it reaches the compressive strength corresponding to its class (grade).

3.2. The frost resistance of concrete is controlled by testing cube samples with dimensions of 100 x 100 x 100 mm or cylinder samples with a diameter and height of 100 mm.

3.3. Samples (cubes or cylinders) are cut only from the middle part of control unreinforced blocks or products in accordance with GOST 10180. It is allowed to make samples in individual forms, meeting the requirements of GOST 22685.

3.4. Samples intended to control frost resistance are taken as the main ones.

Samples intended to determine compressive strength without freezing and thawing are taken as control samples.

3.5. Number of samples for testing according to table. 3 should be at least 21 (12 - main, six - control for the established and intermediate cycles and three - for determining the loss of concrete mass).

3.6. Before testing for frost resistance, the main and control concrete samples must be saturated with water at a temperature of (18 + 2) °C.

The samples are saturated by immersing them in water (providing conditions that prevent them from floating) to 1/3 of their height and then keeping them for 8 hours; then by immersing them in water to 2/3 of their height and keeping them in this state for another 8 hours, after which the samples are completely immersed and kept in this state for another 24 hours. In this case, the samples must be surrounded on all sides by a layer of water of at least 20 mm.

4. Testing

4.1. The main samples are loaded into the freezer at a temperature of minus 18 ° C in containers or placed on the mesh shelves of the chamber racks so that the distance between the samples, the walls of the containers and the overlying shelves is at least 50 mm. If, after loading the chamber, the air temperature in it rises above minus 16 °C, then the beginning of freezing is considered to be the moment the temperature in the chamber reaches minus 16 °C.

4.2. The air temperature in the freezer should be measured in the center of its working volume in close proximity to the samples.

4.3. The duration of one freezing cycle at a steady temperature in the chamber of minus (18 + 2) °C must be at least 4 hours, including the time of temperature transition from minus 16 °C to minus 18 °C.

4.4. Samples after being unloaded from freezer thawed in a defrosting chamber at a temperature of (18 + 2) °C and relative humidity (95 + 2)%.

The samples in the thawing chamber are placed on the mesh shelves of the racks so that the distance between them, as well as from the overlying shelf, is at least 50 mm. The duration of one defrosting cycle must be at least 4 hours.

4.5. The number of freezing and thawing cycles of the main concrete samples within 1 day must be at least one. During forced breaks during frost resistance tests, the samples must be in a thawed state to prevent them from drying out (in a thawing chamber).

4.6. Control samples Before the compression test, it is kept in a defrost chamber for a time corresponding to the number of cycles indicated in the table. 3.

Table 3

4.7. The compressive strength, weight and moisture content of the main and control samples are determined through the number of cycles indicated in the table. 3.

4.8. If obvious signs of destruction of the samples appear, they are tested for compression ahead of schedule, earlier than the cycles indicated in Table. 3.

5. Processing of results

5.1. According to the results of the compression test of the main samples after the specified in table. 3 numbers of cycles, as well as control samples, determine the strength and calculate the coefficient of variation of the control samples according to GOST 10180, which should be no more than 15%, and also determine their weight loss.

5.2. The relative reduction in strength (RK,),%, of the main samples is calculated using the formula

Where /? mtn is the average strength of the main samples after a given number of test cycles, MPa;

i?mtk - average strength value of control samples, MPa.

5.3. Mass loss D t, %, of samples is calculated using the formula

m n (l-w n)-m n (l-w n) (5)

Дт = -п-;-" 100 >

^ t n (1 - w n)

where t p is the average mass of the main samples after water saturation according to clause 3.6, g;

w n - average moisture content of control samples in parts of one after water saturation _ according to clause 3.6;

t p - the average value of the mass of the main samples after passing through a specified or intermediate number of cycles, g;

w n is the average moisture content of the main samples in parts of unity after passing through a specified or intermediate number of cycles.

5.4. The moisture content of concrete is determined according to GOST 12730.2 on samples of control samples after completion of their water saturation and from the main samples - immediately after their strength testing.

Samples for determining humidity are taken from three control and three main samples.

5.5. The grade of concrete for frost resistance corresponds to the required one if the relative decrease in the strength of concrete after passing the number of test cycles equal to the required one is less than 15%, and the average weight loss of a series of basic samples does not exceed 5%.

5.6. The grade of concrete in terms of frost resistance does not correspond to the required one if the relative decrease in the strength of concrete after undergoing cycles numerically equal to the required grade is more than 15% or the average weight loss of a series of basic concrete samples exceeds 5%. In this case, the frost resistance grade of concrete corresponds to the number of cycles equal to the previous grade.

5.7. The grade of concrete for frost resistance does not correspond to the required one if the relative decrease in the strength of concrete after passing intermediate test cycles is more than 15% or the average weight loss of a series of basic samples is more than 5%.

5.8. The initial data and test results of control and main samples must be entered in the test log in the form given in Appendix 4.

Head of laboratory

Last name, first name, report

METHOD FOR DETERMINING THE ELASTIC MODULE

This method applies to non-autoclaved concrete at design age and autoclaved concrete and establishes the elastic modulus when testing beam specimens in bending.

The method is based on the equality of the values ​​of the modulus of elasticity of concrete under compression and tension using a graph (diagram) of the “load-strain” relationship of the tensile surface of the sample, recorded during its continuous loading with constant speed until destruction.

1. Samples, their production and selection

1.1. The elastic modulus is determined on beam samples measuring 40 x 40 x 160 mm

1.2. Samples are produced in batches. The series must consist of at least three samples.

1.3. Samples are cut from finished products or from control unreinforced blocks manufactured simultaneously with the products. Cutting patterns are adopted in accordance with GOST 10180. The longitudinal axis of the samples must correspond to the direction in which the elastic modulus is determined, taking into account the operating conditions of the structure or product during operation (perpendicular or parallel to the direction of concrete swelling).

1.4. Deviations of the sizes and shapes of samples from the nominal ones should not exceed the values ​​​​established by GOST 10180.

2. Requirements for equipment and devices

2.1. For testing use:

Testing machines or loading installations and a device for testing concrete for tensile bending in accordance with GOST 10180;

Conductor strain gauges with a base of 20 mm per paper based according to GOST 21616;

An electrical force meter, for example a strain gauge force sensor according to GOST 28836. The error of the force meter should not exceed + 1%;

An intermediate measuring transducer, for example a strain gauge amplifier and a two-coordinate recording device matched with it according to TU 25-05.7424.021;

Adhesive for gluing strain gauges, for example BF-2 according to GOST 12172;

Instruments and means for weighing samples, measuring them, determining geometric accuracy, etc. in accordance with GOST 10180.

2.2. Testing machines, installations and instruments must be certified and tested in accordance with the established procedure in accordance with GOST 8.001*.

3. Preparation for testing

3.1. On the samples, select the faces to which forces should be applied during the loading process, and the tensile surface on which the strain gauge should be glued, and mark the places of support, transmission of forces and sticking of the strain gauges according to the loading diagram prototype, given in hell. 3. The bending plane of the samples during drying should be perpendicular to the direction of swelling of concrete with the longitudinal axis of the sample and parallel to the direction of swelling if the longitudinal axis of the sample is parallel to the direction of swelling of concrete.

3.2. Measure linear dimensions samples in accordance with GOST 10180.

3.3. Before testing, samples must be kept in the laboratory where the test is being carried out for at least 2 hours.

4. Testing

4.1. The samples are weighed (accuracy within + 1%) and installed in the testing device.

4.2. The strain gauge is connected to the measuring system.

4.3. Set the recording scale on the two-coordinate recorder. Expected breaking force (scale vertical axis) is established by testing one or two samples without strain gauges. The expected maximum deformation (horizontal axis scale) is taken to be 1.2 mm/m.

Loading diagram of the prototype

1 - prototype; 2 - strain gauge with a base of 20 mm; 3 - electric force meter

4.4. The sample is loaded according to the diagram shown in Fig. 3, a continuously increasing load, providing a rate of stress increase in the sample of (0.05 + 0.2) MPa/s [(0.5 + 0.2) kgf/(cm 2 s)], and write down the load-strain diagram » stretched surface of the sample until its destruction.

4.5. After the destruction of the sample, the cross section of its rupture is examined and, if there are defects, their location and size are recorded in the form of a diagram on a recorded diagram.

4.6. The moisture content of the sample material is determined according to GOST 12730.2.

5. Processing of results

5.1. The elastic modulus is determined for each sample from the recorded load-strain diagram of the tensile surface of the sample e as follows:

A tangent is drawn to the curve F-e at its starting point at F = 0 (Fig. 4). The tangent cuts off a segment on the line corresponding to the destructive load F u, the length of which is equal to the elastic component of the limiting relative tensile strain e^;

Graph of the dependence of the concrete deformation of the tensile surface of the sample on the bending load

F - load; F u - breaking load; еы is the deformation of the tensile surface of the sample; eаы - ultimate relative deformation sprains

The value of the elastic modulus Eb is calculated using the formula

Eb = K y/ £ uЪР (6)

where R bt is the value of tensile strength during bending, MPa (kgf/cm2), calculated by the formula

R H = M u /W= FJ/6W, (7)

where M and is the breaking bending moment, N m (kgf cm);

/ - distance between supports, m (cm);

W- moment of resistance cross section sample, m 3 (cm 3), calculated by the formula

where b is the cross-sectional width of the sample, m (cm); h - cross-sectional height of the sample, m (cm).

5.2. The elastic modulus of concrete in a series is determined as the arithmetic mean of the elastic modulus of all tested samples.

Note: If there are significant defects in the fracture section of the samples, the test result is not taken into account when calculating the average value.

5.3. The average density of the material of each sample is calculated according to GOST 12730.1.

5.4. The log of test results must be drawn up in accordance with the requirements of GOST 10180 and GOST 24452. Recorded deformation diagrams must be attached to the log.

INFORMATION DATA

1. DEVELOPED by the Research, Design and Technological Institute of Concrete and Reinforced Concrete (NIIZhB) of the USSR State Construction Committee

Central Research and Design-Experimental Institute of Complex Problems of Building Structures and Structures named after V.A. Kucherenko (TsNIISK named after V.A. Kucherenko) of the USSR State Construction Committee

Research Institute of Building Physics (NIISF) of the State Construction Committee of the USSR Leningrad Zonal Research and Design Institute of Standard and Experimental Design of Residential and Public Buildings (LenZNNNEP) of the State Committee for Architecture of the USSR State Construction Committee of the USSR

INTRODUCED by the Research, Design and Technological Institute of Concrete and Reinforced Concrete (NIIZhB) of the USSR State Construction Committee

2. APPROVED AND ENTERED INTO EFFECT by Resolution of the State Construction Committee of the USSR dated March 30, 1989 No. 57

3. INSTEAD GOST 25485-83, GOST 12852.3-77, GOST 12852.4-77

4. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

			Number of section, paragraph, application
GOST 4.212-80		GOST 4221-76	1.3.9.6, Appendix 2
GOST 8.001-80	Appendix 5	GOST 5100-85
		GOST 5494-95
GOST 2067-93		GOST 5742-76	Annex 1
GOST 2263-79	1.3.9.5, 1.3.9.6	GOST 7076-99
GOST 3252-80		GOST 8736-93
GOST 3476-74		GOST 9179-77
GOST 4013-82		GOST 10060.0-95	Appendix 3

Continuation

	Number of section, paragraph, application		Number of section, paragraph, application
GOST 10178-85		GOST 22685-89	Appendix 3
GOST 10180-90	3, appendices 2, 3, 5	GOST 23732-79
GOST 11024-84	Annex 1	GOST 24104-2001	Appendix 2
GOST 11118-73		GOST 24452-80	3, appendix 5
GOST 12172-74	Appendix 5	GOST 24816-81
GOST 12504-80	Annex 1	GOST 25192-82
GOST 12730.1-78	3, appendix 5	GOST 25336-82	Appendix 2
GOST 12730.2-78	3, appendices 3, 5	GOST 25898-83
GOST 13015.1-81		GOST 27005-86
GOST 13078-81		GOST 27006-86
GOST 17177-94		GOST 28836-90	Appendix 5
GOST 17623-87		OST 6-05-386-80
GOST 18105-86			1.3.9.1, 1.3.9.2
GOST 19113-84		TU 6-09-2448-78
GOST 19570-74	Annex 1	TU 6-14-625-80
GOST 21458-75		TU 25-05.7424.021-86	Appendix 5
GOST 21520-89	Annex 1	TU 38-107101-76
GOST 21616-91 GOST 21718-84	Appendix 5 3	ST SEV 1406-78

5. REPUBLICATION. April 2003

Editor V.P. Ogurtsov Technical editor N.S. Grishanova Proofreader V.S. Chernaya Computer layout S.V. Ryabova

Ed. persons No. 02354 dated July 14, 2000. Delivered for recruitment on 04/16/2003. Signed for publication on June 16, 2003. Conditions of sadness 1.86. Academician-ed.l. 1.50.

Circulation 124 copies. From 10813. Zak. 510.

IPK Standards Publishing House, 107076 Moscow, Kolodezny per., 14. e-mail:

Typed at the Publishing House on a PC

Branch of IPK Standards Publishing House - type. “Moscow Printer”, 105062 Moscow, Lyalin lane, 6.

GOST 25485-89

INTERSTATE STANDARD

CELLULAR CONCRETE

TECHNICAL CONDITIONS

IPC PUBLISHING HOUSE OF STANDARDS
Moscow

INTERSTATE STANDARD

Date of introduction 01.01.90

This standard applies to cellular concrete (hereinafter referred to as concrete).

The requirements of this standard must be observed when developing new and revising existing standards and technical specifications, design and technological documentation for products and structures made from these concretes, as well as during their manufacture.

1. TECHNICAL REQUIREMENTS

1.1. Concrete must meet the requirements of GOST 25192 and they should be manufactured in accordance with the requirements of this standard according to technological documentation approved in the prescribed manner.

1.2. Main settings

1.2.1. Concrete is divided into:

Purpose;

Hardening conditions;

Method of pore formation;

Types of binders and siliceous components.

1.2.2. According to their intended purpose, concrete is divided into:

Structural;

Structural and thermal insulation;

Thermal insulation.

1.2.3. According to hardening conditions, concrete is divided into:

Autoclave (synthetic hardening) - hardening in a saturated steam environment at a pressure above atmospheric;

Non-autoclave (hydration hardening) - hardening under natural conditions, during electrical heating or in an environment of saturated steam at atmospheric pressure.

1.2.4. Based on the method of pore formation, concrete is divided into:

Aerated concrete;

Foam concrete;

Gas foam concrete.

1.2.5. Based on the type of binder and siliceous components, concretes are divided into:

According to the type of main binder:

on lime binders consisting of lime-lime more than 50% by weight, slag and gypsum or cement additives up to 15% by weight;

on cement binders in which the Portland cement content is 50% or more by weight;

on mixed binders consisting of Portland cement from 15 to 50% by weight, lime or slag, or slag-lime mixture;

on slag binders, consisting of slag more than 50% by weight in combination with lime, gypsum or alkali;

on ash binders, in which the content of highly basic ash is 50% or more by weight;

By type of silica component:

on natural materials - finely ground quartz and other sands;

on secondary industrial products - fly ash from thermal power plants, hydraulic removal ash, secondary products from the enrichment of various ores, ferroalloy waste and others.

1.2.6. The names of concretes must include both basic and specific characteristics: purpose, hardening conditions, method of pore formation, type of binder and siliceous components.

1.3.Characteristics

1.3.1. The strength of autoclaved and non-autoclaved concrete is characterized by classes of compressive strength in accordance with ST SEV 1406.

The following classes are established for concrete: B0.5; B0.75; IN 1; B1.5; AT 2; B2.5; B3.5; AT 5; B7.5; AT 10 O'CLOCK; B12.5; B15.

For structures designed without taking into account the requirements of ST SEV 1406, the compressive strength of concrete is characterized by the following grades: M7.5; M10; M15; M25; M35; M50; M75; M100; M150; M200.

1.3.2. Based on average density indicators, the following grades of concrete in a dry state are prescribed: D300; D350; D400; D500; D600; D700; D800; D900; D1000; D1100; D1200.

1.3.3. For concrete structures subject to alternating freezing and thawing, the following grades of concrete are assigned and controlled for frost resistance: F15; F25; F35; F50; F75; F100.

The assignment of a concrete grade for frost resistance is carried out depending on the operating mode of the structure and the calculated winter temperatures of the outside air in the construction areas.

1.3.4. Indicators of physical and mechanical properties of concrete are given in table. .

Table 1

Indicators of physical and mechanical properties of concrete

Type of concrete	Concrete grade by average density	Autoclaved concrete		Non-autoclaved concrete
		Compressive strength class	Frost resistance grade	Compressive strength class	Frost resistance grade
Thermal insulation	D300	B0.75	Not standardized
		B0.5
	D350
		B0.75
	D400	B1.5		B0.75	Not standardized
				B0.5
	D500
				B0.75
Structural and thermal insulation	D500	B2.5	From F15 to F35
		B1.5
	D600	B3.5	From F15 to F75		From F15 to F 35
		B2.5
		B1.5
	D700		From F15 to F100	B2.5 B1.5	From F15 to F50
		B3.5
		B2.5
	D800	B7.5		B3.5 B2.5	From F15 to F75
		B3.5
		B2.5
	D900	AT 10	From F15 to F75	B3.5 B2.5
		B7.5
		B3.5
Structural	D1000	B12.5	From F15 to F50	B7.5	From F15 to F50
		AT 10
		B7.5
	D1100	B15		AT 10 B7.5
		B12.5
		AT 10
	D1200	B15		B12.5 AT 10
		B12.5

In addition, when studying new properties of concrete and for the data necessary for normalizing the design characteristics of concrete, the quality of concrete is characterized by prismatic strength, elastic modulus, and tensile strength.

1.3.9. Materials

1.3.9.1. Binders used for concrete:

Highly basic ash according to OST 21-60, containing CaO of at least 40%, including free CaO of at least 16%, SO 3 - no more than 6% and R 2 O - no more than 3.5%.

1.3.9.2. Siliceous components used for concrete:

Foaming agent based on:

technical caustic soda according to GOST 2263;

scrubber paste according to TU 38-107101 and other foaming agents.

1.3.9.6. Regulators of structure formation, increase in plastic strength, hardening accelerators and plasticizing additives:

Gypsum and gypsum anhydrite stone according to GOST 4013;

Technical soda ash according to GOST 5100;

Liquid sodium glass according to GOST 13078;

Triethanolamine according to TU 6-09-2448;

Superplasticizer S-3 according to TU 6-14-625;

Carboxylmethylcellulose according to OST 6-05-386;

Sodium sulfate crystallization according to GOST 21458 and other additives.

1.3.9.7. Water for preparing concrete - according to GOST 23732.

1.3.9.8. Selection of concrete compositions - in accordance with GOST 27006, methods, manuals and recommendations of research institutes, approved in the prescribed manner.

1.4. Labeling and packaging

Marking and packaging of products and structures made of concrete are carried out in accordance with the requirements of standards or technical specifications for products and structures of specific types.

2. ACCEPTANCE

2.1. Acceptance of concrete products and structures - in accordance with GOST 13015.1 and standards or technical specifications for specific types of structures.

2.2. Acceptance of concrete for strength, average density and release moisture content is carried out for each batch of products.

2.3. Control of concrete in terms of frost resistance, thermal conductivity and drying shrinkage is carried out before the start of mass production, when technology and materials change, while in terms of frost resistance and drying shrinkage - at least once every 6 months and in terms of thermal conductivity - at least once every year.

2.4. Concrete control in terms of sorption humidity, vapor permeability, prismatic strength, elastic modulus is carried out according to standards or technical specifications for products and structures of specific types.

2.5. Concrete strength control is carried out according to GOST 18105, medium density - according to GOST 27005.

3. CONTROL METHODS

Physical and technical indicators are monitored by:

Compressive and tensile strength - according to GOST 10180;

Frost resistance - according to the application;

Drying shrinkage - according to the application;

Sorptive humidity - according to GOST 24816 and GOST 17177;

4. TRANSPORTATION AND STORAGE

Transportation and storage of concrete structures is carried out in accordance with the requirements of standards or technical specifications for products and structures of specific types.

ANNEX 1

1. External concrete and reinforced concrete wall panels for residential and public buildings in accordance with GOST 11024.

2. Panels made of autoclaved cellular concrete for internal load-bearing walls, partitions and ceilings of residential and public buildings in accordance with GOST 19570.

3. Heat-insulating products made from cellular concrete according to GOST 5742.

4. Small cellular concrete wall blocks according to GOST 21520.

5. Internal concrete and reinforced concrete wall panels for residential and public buildings in accordance with GOST 12504.

6. Panels made of autoclaved cellular concrete for external walls of buildings in accordance with GOST 11118.

Note. Autoclave concretes are used for the manufacture of the entire recommended range of products and structures, non-autoclave concretes are used mainly for the manufacture of small wall blocks and thermal insulation.

APPENDIX 2

Mandatory

METHOD FOR DETERMINING DRYING SHRINKAGE

The essence of the method is to determine the change in the length of a concrete sample (in millimeters) when its moisture content changes from 35% to 5% by weight.

1. Preparation and selection of samples

Laboratory drying cabinet type SNOL;

Bath with lid;

Anhydrous potassium carbonate according to GOST 4221.

3. Preparation for testing

3.1. In the center of each end face of the sample, a stainless steel reference is strengthened with quickly polymerizing glue; for this, a square plate with a thickness of at least 1 mm with ribs of at least 10 mm and a hole with a diameter of 1.5 mm in the center is used.

It is allowed to use glue of the following composition, g:

Epoxy resin……………………………………80

Polyethylenepolyamine………………………………. 3

Dibutyl phthalate……………………………………. 1

3.2. Before testing, measure the length of the samples and weigh them.

Sample measurement error is in accordance with GOST 10180.

4. Testing

4.1. Samples are saturated with water by immersing them in a horizontal position in water at a temperature of (20 ± 2) °C for 3 days to a depth of 5 - 10 mm.

4.2. After saturation, the samples are kept in a tightly closed desiccator over water at a temperature of (20 ± 2) °C for 3 days.

4.3. Immediately after removal from the desiccator, the samples are weighed and an initial reading is made using the indicator.

The error in weighing samples should be ±0.1 g, the error in determining changes in sample length is ±0.005 mm.

4.4. A series of samples are placed in a tightly closed desiccator positioned over anhydrous potassium carbonate. For a series of samples, every 7 days of testing, take (600 ± 10) g of potassium carbonate. Every 7 days, wet potassium carbonate is replaced with dry one.

4.5. The temperature of the room in which samples are tested must be (20 ± 2) °C.

4.6. During the first four weeks, changes in the length and weight of the samples are determined every 3 to 4 days. Subsequently, measurements are carried out at least once a week until the samples reach a constant mass.

The mass of samples is considered constant if the results of two consecutive weighings carried out at an interval of one week differ by no more than 0.1%.

4.7. After completing the shrinkage measurement, the samples are dried at a temperature of (105 ± 5) °C to constant weight and weighed.

5. Processing of results

5.1. For each sample calculate:

Drying shrinkage value (e i), mm/m, after each measurement according to the formula

Where t i - weight of wet sample after i days of exposure in a desiccator over potassium carbonate, g;

m 0 - weight of the sample dried at a temperature of (105 ± 5) °C, g.

5.2. By values ​​of e i And w i construct a shrinkage curve for each sample. An approximate shrinkage curve is shown in Fig. .

A chamber for thawing samples, equipped with a device for maintaining relative humidity (95 ± 2)% and temperature (18 ± 2) °C;

Bath for saturating samples;

Mesh racks in the freezer;

Mesh containers for placing samples.

2.2. To control the frost resistance of concrete, chambers with automatic temperature and humidity control can be used, providing the ability to maintain the temperature and humidity specified in paragraph.

3. Preparation for testing

3.1. Frost resistance tests of concrete are carried out when it reaches the compressive strength corresponding to its class (grade).

3.2. The frost resistance of concrete is controlled by testing cube samples with dimensions of 100´ 100´ 100 mm or cylinder samples with a diameter and height of 100 mm.

3.3. Samples (cubes or cylinders) are cut only from the middle part of control unreinforced blocks or products in accordance with GOST 10180. When carrying out research work, as well as for testing foam concrete, it is allowed to produce samples in individual forms that meet the requirements of GOST 22685.

3.4. Samples intended to control frost resistance are taken as the main ones.

Samples intended to determine compressive strength without freezing and thawing are taken as control samples.

3.5. Number of samples for testing according to table. should be at least twenty-one (12 - main, six - control for the established and intermediate cycles and three - for determining the loss of concrete mass).

Concrete grade for frost resistance						F100
Number of cycles after which concrete samples are tested for compression

4.7. The compressive strength, weight and moisture content of the main and control samples are determined through the number of cycles indicated in the table. .

4.8. If obvious signs of destruction of the samples appear, they are tested for compression ahead of schedule, earlier than the cycles indicated in Table. .

5. Processing of results

5.1. According to the results of the compression test of the main samples after the specified in table. the number of cycles, as well as control samples, determines the strength and calculates the coefficient of variation of control samples according to GOST 10180, which should be no more than 15%; and also determine the loss of their mass.

5.2. Relative reduction in strength ( R rel),%, of the main samples are calculated using the formula

Where T n is the average value of the mass of the main samples after water saturation according to item, g;

w n is the average moisture content of control samples, in parts of unity, after water saturation according to item;

Average value of the mass of the main samples after passing through a specified or intermediate number of cycles, g;

The average moisture content of the base samples, in parts of unity, after a specified or intermediate number of cycles.

5.4. The moisture content of concrete is determined according to GOST 12730.2 on samples from control samples after completion of their water saturation and from main samples - immediately after their strength testing.

Samples for determining humidity are taken from three control and three main samples.

5.5. The grade of concrete for frost resistance corresponds to the required one if the relative decrease in the strength of concrete after passing the number of test cycles equal to the required one is less than 15%, and the average weight loss of a series of basic samples does not exceed 5%.

5.6. The grade of concrete in terms of frost resistance does not correspond to the required one if the relative decrease in the strength of concrete after undergoing cycles numerically equal to the required grade is more than 15% or the average weight loss of a series of basic concrete samples exceeds 5%. In this case, the frost resistance grade of concrete corresponds to the number of cycles equal to the previous grade.

5.7. The grade of concrete for frost resistance does not correspond to the required one if the relative decrease in the strength of concrete after passing intermediate test cycles is more than 15% or the average weight loss of a series of basic samples is more than 5%.

5.8. The initial data and test results of the control and main samples must be entered in the test log in the form given in the appendix.

APPENDIX 4

Form of a logbook for testing concrete samples for frost resistance

Initial data of control and main samples
							control
Date of receipt of samples	Batch (series) number and markings	Dimensions, mm	Date of manufacture	Class (grade) of concrete by compressive strength B(M)	Design grade of concrete for frost resistance F	Signatures of the responsible persons who accepted the samples for testing	Date of testing	Weight, g	Compressive strength, MPa	Humidity, %

Table continuation

Sample test results

Conclusion on the results of testing concrete for frost resistance

Signatures of responsible persons

Note

main

Intermediate tests

Final tests

Start date of testing concrete for frost resistance

Weight of samples in a saturated state before testing, g

Date of testing

Number of intermediate cycles

Weight, g

Compressive strength, MPa

Humidity, %

Signature responsible person who conducted the tests

Date of testing

Number of cycles

Weight, g

Compressive strength, MPa

Humidity, %

Head of laboratory ___________________ ____________________________________

(Full Name)

APPENDIX 5

METHOD FOR DETERMINING THE ELASTIC MODULE

This method applies to non-autoclaved concrete at design age and autoclaved concrete and establishes the elastic modulus when testing beam specimens in bending.

The method is based on the equality of the values ​​of the elastic modulus of concrete under compression and tension using a graph (diagram) of the “load - deformation” relationship of the tensile surface of the sample, recorded during its continuous loading at a constant speed until failure.

1. Samples, their production and selection

1.1. The elastic modulus is determined on beam samples with dimensions of 40´ 40´ 160 mm.

1.2. Samples are produced in batches. The series must consist of at least three samples.

1.3. Samples are cut from finished products or from control unreinforced blocks manufactured simultaneously with the products. Cutting patterns are accepted according to GOST 10180. The longitudinal axis of the samples must correspond to the direction in which the elastic modulus is determined, taking into account the operating conditions of the structure or product during operation (perpendicular or parallel to the direction of concrete swelling).

1.4. Deviations of the sizes and shapes of samples from the nominal ones should not exceed the values ​​​​established by GOST 10180.

2. Requirements for equipment and devices

2.1. For testing use:

Testing machines or loading installations and a device for testing concrete for tensile bending in accordance with GOST 10180;

Conductor strain gauges with a base of 20 mm on a paper base in accordance with GOST 21616;

Electric force meter, for example, a strain gauge force sensor according to GOST 28836. The error of the force meter should not exceed ±1%;

An intermediate measuring transducer, for example, a strain gauge amplifier and a two-coordinate recording device matched with it according to TU 25-05.7424.021;

Adhesive for gluing strain gauges, for example BF-2, according to GOST 12172;

Instruments and means for weighing samples, measuring them, determining geometric accuracy, etc. according to GOST 10180.

2.2. Testing machines, installations and instruments must be certified and tested in accordance with the established procedure in accordance with GOST 8.001 *.

_______

* In the territory Russian Federation PR 50.2.009-94 is valid.

3. Preparation for testing

3.1. On the samples, select the faces to which forces should be applied during the loading process, and the tensile surface on which the strain gauge should be glued, and mark the places of support, transmission of forces and sticking of the strain gauges according to the loading diagram of the prototype shown in Fig. . The bending plane of the samples during drying should be perpendicular to the direction of swelling of the concrete with the longitudinal axis of the sample and parallel to the direction of swelling if the longitudinal axis of the sample is parallel to the direction of swelling of the concrete.

3.2. The linear dimensions of the samples are measured in accordance with GOST 10180.

3.3. Before testing, samples must be kept in the laboratory where the test is being carried out for at least 2 hours.

4. Testing

4.1. The samples are weighed (accuracy within ± 1%) and installed in the testing device.

4.2. The strain gauge is connected to the measuring system.

1 - prototype; 2 - strain gauge with a base of 20 mm; 3 - electric force meter

4.4. The sample is loaded according to the diagram shown in Fig. , a continuously increasing load, providing a rate of increase in stress in the sample (0.05 ± 0.2) MPa/s [(0.5 ± 0.2) kgf/(cm 2 × s)], write down the “load-strain” diagram stretched surface of the sample until its failure.

4.5. After the destruction of the sample, the cross section of its rupture is examined and, if there are defects, their location and size are recorded in the form of a diagram on a recorded diagram.

4.6. The moisture content of the sample material is determined according to GOST 12730.2.

5. Processing of results

5.1. The elastic modulus is determined for each sample from the recorded load-strain diagram of the tensile surface of the sample e bt in the following way:

Towards the curve F- e bt draw a tangent at its starting point at F= 0 (damn). The tangent cuts off at the line corresponding to the breaking load F u, a segment whose length is equal to the elastic component of the maximum relative tensile strain e ubt;

Graph of the deformation of concrete on a tensile surface
sample against bending load

F u - e bt - deformation of the tensile surface of the sample;
e u bt - ultimate relative tensile strain

Elastic modulus value E b is calculated using the formula

Where M u - breaking bending moment, N × m (kgf × cm);

l - distance between supports, m (cm);