SP 15 13330.2012 stone and reinforced stone structures. Types of stone and reinforced stone structures, their scope. Stone and reinforced stone structures of residential, civil and industrial buildings. Calculation of elements of stone structures. Additional requirements

Stone materials. As stone materials For masonry, piece stones weighing no more than 40 kg and factory-made stone products are used, the weight of which is limited by the carrying capacity of transport and installation equipment. Piece stone materials include: ceramic bricks, ceramic stones, natural stones correct form and rubble ( irregular shape), concrete stones. Stone products are produced in the form of concrete blocks for various purposes, blocks of brick and ceramic stones, vibrating brick panels, blocks of natural stones and so on.

Stone materials are classified: by origin: a) natural stones mined in stone quarries (stone blocks, rubble); b) artificial stones made by firing (brick, ceramic stones), and non-fired stones (silicate brick, slag brick, concrete stones from heavy and light concrete); by structure: a) solid brick and solid stones; b) hollow bricks and stones with voids of various shapes.

Brick is used for hand masonry the following types: ceramic ordinary plastic and semi-dry pressing, ceramic hollow plastic pressing, silicate brick, brick made of tripoli and diatomites.

Solid ceramic and sand-lime bricks are used for masonry bearing walls and pillars; ceramic hollow - for laying external walls of heated buildings. Ceramic and concrete stones are used in the construction of walls and partitions, and large blocks of heavy concrete are also used for laying foundation walls.

Natural stones from heavy rocks (limestone, sandstone, granite) are used mainly for cladding walls and laying foundations, and in some areas walls are built from light rocks (tuff, limestone, shell rock).

The main characteristic of stone materials used in load-bearing structures is their strength, characterized by a grade that indicates the temporary resistance of the samples under compression.

Fittings. For reinforcement of stone structures, it should be used: as mesh reinforcement - hot-rolled round steel of class A-1 or reinforcing wire of a periodic profile of class Vr-1 with a diameter of 3 ... 8 mm, as longitudinal and transverse reinforcement - steel of classes A-1, A -11 and Vr-1 with a diameter of 5...8 mm. Connecting elements, embedded parts and steel clips should be made from rolled sheet steel, shaped profiles, strip steel.

The calculation of stone and reinforced masonry structures is carried out according to the limit state method. In this case, 2 groups of limit states are taken into account: the first in terms of bearing capacity (strength and stability), the second - in the formation and opening of cracks (masonry seams) and deformations. Calculations according to the first group are always performed for all types of structures. The calculation for the second group is carried out for structures where cracks are not allowed (tank lining) or their incomplete opening is required (eccentrically compressed elements with large eccentricities), deformations are limited under the conditions of joint operation of adjacent structures (wall fillings of building frames), etc. The purpose of the calculation is selecting sections of elements or checking existing sections. The calculated stresses, deformations and crack widths should not exceed the limit values ​​​​established by the standards.

The calculation for bearing capacity is made from the condition that the design force N is less than or equal to the design bearing capacity. The design force is calculated under the action of loads taken with a safety factor under their unfavorable combination. The design load-bearing capacity is determined depending on the geometric dimensions of the section, the design resistance of the masonry R and the operating conditions coefficients. Design resistance, taking into account the possibility of a decrease in strength associated with the natural variation in mechanical properties, is taken into account by the reliability coefficient and is determined by the formula

Moscow 1995

Developed by the Central Research Institute of Building Structures (TsNIISK) named after. V.A. Kucherenko State Construction Committee of the USSR.

With the entry into force of this chapter of SNiP, chapter SNiP 11-6.2-71 “Stone and reinforced stone structures. Design standards".

Editors - engineers F.M. Shlemin, G.M. Khorin(Gosstroy USSR) and candidates of technical. Sciences V.A. Kameiko, A.I. Rabinovich(TsNIISK named after V.A. Kucherenko).

At the end of the document there is an amendment to SNiP II-22-81, approved by Decree of the USSR State Construction Committee dated September 11, 1985 No. 143.

When using a regulatory document, you should take into account the approved changes building codes and rules and state standards published in the journal "Bulletin of Construction Equipment" and the information index "State Standards" of the State Standard of Russia.

1. General Provisions

1.1. The standards of this chapter must be observed when designing masonry and reinforced masonry structures of new and reconstructed buildings and structures.

1.2. When designing stone and reinforced masonry structures, you should use Constructive decisions, products and materials:

a) external walls made of: hollow ceramic and concrete stones and bricks; lightweight brickwork with slab insulation or backfill made of porous aggregates; solid stones and concrete blocks on porous aggregates, porous and cellular concrete. The use of solid masonry made of solid clay or silicate bricks for the external walls of rooms with dry and normal humidity conditions allowed only if it is necessary to ensure their strength;

b) walls made of panels and large blocks made of various types of concrete, as well as brick or stones;

c) bricks and stones of grades with a compressive strength of 150 or more in buildings with a height of more than five floors;

d) local natural stone materials;

e) solutions with antifreeze chemical additives for winter masonry, taking into account the instructions of Section. 7.

Note. With appropriate justification, it is allowed to use design solutions, products and materials not provided for in this paragraph.

1.3. Application of silicate bricks, stones and blocks; stones and blocks made of cellular concrete; hollow bricks and ceramic stones; semi-dry pressed clay bricks are allowed for external walls of rooms with wet conditions, provided that a vapor barrier coating is applied to their internal surfaces. The use of these materials for the walls of rooms with wet mode, as well as for external walls of basements and plinths is not allowed. The humidity conditions of the premises should be taken in accordance with the chapter of SNiP on construction heating engineering.

1.4. The strength and stability of structures and their elements must be ensured during construction and. operation, as well as during transportation and installation of elements of prefabricated structures.

1.5 . When calculating structures, one should take into account the reliability coefficients UD, adopted in accordance with the Rules for taking into account the degree of responsibility of buildings and structures when designing structures. approved by the USSR State Construction Committee.

1.6. When designing buildings and structures, measures should be taken to ensure the possibility of their construction in winter conditions.

BUILDING REGULATIONS

STONE AND REINFORCED STONE STRUCTURES

SNiP II-22-81

(as amended by Changes,
approved Decree of the USSR State Construction Committee dated September 11, 1985 N 143,
Changes No. 2 adopted by the Resolution
Gosstroy of the Russian Federation dated May 29, 2003 N 46)

Developed by the Central Research Institute of Building Structures (TsNIISK) named after. V.A. Kucherenko State Construction Committee of the USSR.
Introduced by TsNIISK them. Kucherenko State Construction Committee of the USSR.
With the entry into force of this chapter of SNiP, chapter SNiP II-B.2-71 "Masonry and reinforced masonry structures. Design standards" is cancelled.
Editors - engineers F.M. Shlemin, G.M. Khorin (Gosstroy USSR) and candidates of technical sciences. Sciences V.A. Kameiko, A.I. Rabinovich (TsNIISK named after V.A. Kucherenko).
When using a regulatory document, you should take into account the approved changes to building codes and regulations and state standards published in the journal "Bulletin of Construction Equipment" and the information index "State Standards" of the State Standard of Russia.

1. GENERAL PROVISIONS

1.1. The standards of this chapter must be observed when designing masonry and reinforced masonry structures of new and reconstructed buildings and structures.
1.2. When designing masonry and reinforced masonry structures, design solutions, products and materials should be used that provide the required load-bearing capacity and thermal characteristics of the structures.
(clause 1.2 as amended by Amendment No. 2, adopted by Resolution of the State Construction Committee of the Russian Federation dated May 29, 2003 No. 46)
1.3. Application of silicate bricks, stones and blocks; stones and blocks made of cellular concrete; ceramic bricks and stones, concrete blocks with voids; Semi-dry pressed ceramic bricks are allowed for external walls of rooms with wet conditions, provided that a vapor barrier coating is applied to their internal surfaces. The use of these materials for the walls of rooms with a wet regime, as well as for the outer walls of basements and plinths, is not allowed. The humidity regime of the premises should be taken in accordance with the SNiP for thermal protection.

1.4. The strength and stability of stone structures and their elements must be ensured during construction and operation, as well as during transportation and installation of prefabricated structures.
(clause 1.3 as amended by Amendment No. 2, adopted by Resolution of the State Construction Committee of the Russian Federation dated May 29, 2003 No. 46)
1.5 was dropped as of July 1, 2003. - Change No. 2, adopted by Resolution of the State Construction Committee of the Russian Federation dated May 29, 2003 No. 46.
1.6. When designing buildings and structures, measures should be taken to ensure the possibility of their construction in winter conditions.

2. MATERIALS

2.1. Bricks, stones and mortars for stone and reinforced masonry structures, as well as concrete for the manufacture of stones and large blocks must meet the requirements of the relevant GOSTs and apply the following grades or classes:
(as amended by Amendments, approved by Resolution of the USSR State Construction Committee dated September 11, 1985 N 143)
a) stones - in terms of compressive strength (and brick - in compression, taking into account its bending strength): 7, 10, 15, 25, 35, 50 (low-strength stones - light concrete and natural stones); 75, 100, 125, 150, 200 (medium strength - brick, ceramic, concrete and natural stones); 250, 300, 400, 500, 600, 800, 1000 (high strength - brick, natural and concrete stones);

b) concrete classes according to compressive strength;
heavy - B3.5; AT 5; B7.5; B12.5; B15; IN 20; B25; B30;
on porous fillers - B2; B2.5; B3.5; AT 5; B7.5; B12.5; B15; IN 20; B25; B30;
cellular - B1; AT 2; B2.5; B3.5; AT 5; B7.5; B12.5;
large-porous - B1; AT 2; B2.5; B3.5; AT 5; B7.5;
porous - B2.5; B3.5; AT 5; B7.5;
silicate - B12.5; B15; IN 20; 825; B30;
(subparagraph b) as amended. Changes, approved. Decree of the USSR State Construction Committee dated September 11, 1985 N 143)
c) solutions based on compressive strength - 4, 10, 25, 50, 75, 100, 150, 200;
d) stone materials for frost resistance - F 10, F 15, F 25, F 35, F 50, F 75, F 100, F 150, F 200, F 300.
(as amended by Amendment No. 2, adopted by Resolution of the State Construction Committee of the Russian Federation dated May 29, 2003 No. 46)
For concrete, frost resistance grades are the same, except for F 10.
(as amended by Amendment No. 2, adopted by Resolution of the State Construction Committee of the Russian Federation dated May 29, 2003 No. 46)
2.2. Solutions with a dry density of 1500 kg/m3 and more are heavy, up to 1500 kg/m3 are light.
2.3. Design grades for frost resistance of stone materials for the outer part of walls (12 cm thick) and for foundations (full thickness), erected in all construction and climatic zones, depending on the expected service life of structures, but not less than 100, 50 and 25 years , are given in table. 1 and paragraphs. 2.4 and 2.5.

ConsultantPlus: note.
By the Decree of the USSR State Construction Committee of December 5, 1983 N 311, from January 1, 1985, SNiP 2.02.01-83 "Foundations of buildings and structures" were put into effect.

Note. Design marks for frost resistance are set only for materials from which the upper part of the foundations is being built (up to half of the estimated depth of soil freezing, determined in accordance with the chapter of SNiP "Foundations of buildings and structures").

Table 1

┌────────────────────────────┬────────────────────────────────────┐
│ Type of structures │ F values ​​at assumed │
│ │ service life of structures, years │
│ ├───────────┬──────────┬─────────────│
│ │ 100 │ 50 │ 25 │
├────────────────────────────┼───────────┼──────────┼─────────────│
│1. External walls or their │ │ │ │
│ cladding in buildings with │ │ │ │
│ humidity conditions │ │ │ │
│ premises: │ │ │ │
│ a) dry and normal │ 25 │ 15 │ 15 │
│ b) wet │ 35 │ 25 │ 15 │
│ c) wet │ 50 │ 35 │ 25 │
│2. Foundations and underground │ │ │ │
│ parts of walls: │ │ │ │
│ a) made of clay brick │ │ │ │
│ plastic pressing│ 35 │ 25 │ 15 │
│ b) from natural stone │ 25 │ 15 │ 15 │
│ │ │ │ │

ConsultantPlus: note.
By Decree of the USSR State Construction Committee dated August 20, 1984 N 136 from January 1
1986 SNiP 2.03.01-84 “Concrete and
reinforced concrete structures".

│ Notes. 1. Grades for frost resistance of stones, blocks and│
│panels made from concrete of all types should be taken in│
│in accordance with the chapter of SNiP for the design of concrete and│
│reinforced concrete structures. │
│ 2. Frost resistance grades given in table. 1, for everyone│
│building and climatic zones, except those specified in clause 2.5 of these│
│standard, can be reduced for clay brick masonry│
│plastic pressing at one stage, but not lower than F 10 in│
│in the following cases: │

│29.05.2003 N 46) │
│ a) for external walls of rooms with dry and normal│
│humidity conditions (item 1, a), protected from the outside│
│cladding with a thickness of at least 35 mm that meets the requirements│
│according to frost resistance given in table. 1, frost resistance│
│face brick and ceramic stone must be at least F│
│25 for all service life of structures; │
│(as amended by Amendment No. 2, adopted by the Resolution of the State Construction Committee of the Russian Federation dated│
│29.05.2003 N 46) │
│ b) for external walls with damp and wet conditions of rooms│
│(pos. 1, b and 1, c), protected from the inside│
│waterproofing or vapor barrier coatings; │
│ c) for foundations and underground parts walls of buildings with│
│sidewalks or blind areas erected in low-moisture soils, if│
│level groundwater below the planning mark of the earth by 3 m and │
│more (item 2). │
│ 3. Frost resistance grades given in pos. 1 for│
│claddings with a thickness of less than 35 mm are increased by one step, but not│
│above F 50, and the cladding of buildings erected in Northern│
│construction-climatic zone, - by two levels, but not higher│
│F 100. │
│(as amended by Amendment No. 2, adopted by the Resolution of the State Construction Committee of the Russian Federation dated│
│29.05.2003 N 46) │
│ 4. Grades for frost resistance of stone materials given│
│in pos. 2, used for foundations and underground parts of walls,│
│should be increased by one step if the groundwater level is lower│
│planning level of the ground less than 1 m. │
│ 5. Stone grades according to frost resistance for open masonry│
│structures, as well as structures of structures erected in the zone│
│variable groundwater levels (retaining walls, reservoirs,│
│weirs, side stones etc.), are accepted according to regulatory standards │
│documents approved or agreed upon by the USSR State Construction Committee. │
│ 6. As agreed with the customer, testing requirements│
│frost resistance is not required for natural stones│
│materials that have been shown by past construction experience│
│sufficient frost resistance under similar operating conditions. │
│(clause 6 of the note as amended by Amendment No. 2 adopted by the Resolution│

│ 7. For external walls of multilayer masonry with thickness│
│outer layer no more than 120 mm, behind which is located│
│insulation, the frost resistance grade of the front layer should be│
│take one step more than the main masonry. │
│(clause 7 of the note was introduced by Amendment No. 2 adopted by the Resolution│
│Gosstroy of the Russian Federation dated May 29, 2003 N 46) │
└─────────────────────────────────────────────────────────────────┘
(as amended by Amendment No. 2, adopted by Resolution of the State Construction Committee of the Russian Federation dated May 29, 2003 No. 46)

2.4. For construction areas located to the east and south of the cities: Grozny, Volgograd, Saratov, Samara, Orsk, Karaganda, Semipalatinsk, Ust-Kamenogorsk, the requirements for frost resistance of materials and products used for the structures specified in Table. 1, it is allowed to reduce by one step, but not lower than F 10.
(as amended by Amendment No. 2, adopted by Resolution of the State Construction Committee of the Russian Federation dated May 29, 2003 No. 46)
Note. The magnitudes of the steps correspond to the values ​​given in paragraph 2.1, d.

2.5. For the Northern building-climatic zone, as well as for the coasts of the Arctic and Pacific Oceans 100 km wide, not included in the Northern building-climatic zone, frost resistance grades of materials for the outer part of the walls (with solid walls - for a thickness of 25 cm) and for foundations ( for the entire width and height) should be one step higher than those indicated in the table. 1, but not higher than F 50 for ceramic and silicate materials, as well as natural stones.
(as amended by Amendment No. 2, adopted by Resolution of the State Construction Committee of the Russian Federation dated May 29, 2003 No. 46)
Note. Definitions of the boundaries of the Northern construction-climatic zone and its subzones are given in the chapter of SNiP on construction climatology and geophysics.

2.6. For the reinforcement of stone structures in accordance with the chapter of SNiP on the design of concrete and reinforced concrete structures, the following should be used:
for mesh reinforcement - reinforcement classes A-I and Bp-I;
for longitudinal and transverse reinforcement, anchors and ties - reinforcement of classes A-I, A-II and Bp-I (taking into account the instructions of clause 3.19).
For embedded parts and connecting plates, steel should be used in accordance with the chapter of SNiP on the design of steel structures.

Due to the ubiquity and availability of raw materials, durability and cost-effectiveness, structures made of natural stone were erected back in the Stone Age. Later, hewn stone, raw brick, and baked brick were used as stone structures.

Stone structures are understood as load-bearing and enclosing structures of buildings and structures, made by connecting individual stones or stone products with mortar. Many outstanding monuments of stone architecture have survived to this day: churches of Kievan Rus of the 10th century, the Archangel Cathedral in the Moscow Kremlin of 1333, the Kremlin walls of 1367. Etc.

The desire of architects to improve designs required the development of methods for their calculation.

In 1638 Galileo was the first to determine the load-bearing capacity of a bent beam under the assumption that the same axial tensile force arises in it as during an axial break, and that at the point of fracture the beam rotates around the face of the section. At the end of the 18th century, Coulomb proposed a theory for calculating a stone vault. In the mid-19th century, the Russian engineer Pauker gave a more accurate graphical definition of the load-bearing capacity of a stone vault.

In 1813 In England, an iron brick factory pipe was built, and in 1825, a tunnel under the Thames made of reinforced masonry. In 1853, a large iron-brick water reservoir was built in Washington.

Reinforced masonry structures have found quite widespread use in our country in the construction of buildings with reinforced brick frames. Traditional materials and designs are widely used. Since 1955, masonry and reinforced masonry structures have been calculated based on their limit states. In the development of the theory and practice of stone structures, the role of V.P. is great. Nekrasova, L.I. Sementsova, S.V. Polyakova, Yu.M. Ivanova and others.

Application stone and reinforced stone structures were found in all climatic regions as load-bearing and enclosing structures for centrally and eccentrically compressed elements with limited eccentricity. Reinforced stone structures are similar in properties to reinforced concrete.

Advantages of stone and reinforced stone structures:

Relatively cheap and accessible material;

High strength characteristics

Disadvantages: -high thermal conductivity;

High labor intensity;

Seasonal limitation of work;

When designing stone and reinforced masonry structures, the requirements

SNiP 11-25-80 Stone and reinforced stone structures

Bricks and stones for stone and reinforced stone structures are produced in the following grades: low-strength stones (light concrete and natural) - 4; 7; 15; 25; 35; 50

Medium strength stones (brick, ceramic, natural, concrete) -75;100;125;150;200

High strength stones (brick, natural, concrete) - 250; 300; 400; 500; 600; 800; 1000

For mortars the following grades are established: 4;10;25;50;75;100;150;200. Grades 150 and 200 are used for free-standing and heavily loaded elements. Solutions with a density (dry) of 1500 kg/m3 or more are called heavy, up to light.

Frost resistance grades F 10-300, depending on the building class and operating mode, design grades 15-50

For reinforcement, the following classes of reinforcement are used: for mesh-A-1; Vr-1; for longitudinal and transverse reinforcement, anchors, ties-A-1; A-11; BP-1

Application: For masonry of external walls with dry and normal humidity conditions, it is recommended to use solid masonry made of hollow bricks, ceramic and lightweight concrete stones, with a wet regime, provided that the internal surface is protected with a vapor barrier, with a wet regime, and for external walls of basements and plinths, it is not allowed. Solid ceramic bricks and stones made of heavy concrete are used for continuous masonry in plinths, basement walls, and in the walls of unheated buildings. Brick grades 150 and more are used in buildings with a height of more than five floors. Sand-lime brick is not used for laying basement walls, and in wet and humid conditions.
Strength and deformation characteristics of masonry

The strength and deformability of masonry depends on many factors:

From the strength and deformability of stone and mortar

Size and shape of stone

Mobility of the solution and the degree of filling of vertical joints with it

Masonry qualities

Mason qualifications, etc.

The strength of stone materials is determined by the results of compression tests of standard samples. The brick is additionally tested for bending. The compressive strength of stone is 10-15 times higher than the tensile strength. According to the compressive strength, the brand of brick is established.

Stone materials are brittle, while mortars in the hardened state are elastic-plastic. Masonry, the bearing capacity of which is provided working together these materials are nonlinearly deformable materials. When masonry perceives compressive forces, the transverse deformations of mortars in horizontal joints significantly exceed the transverse deformations of stone materials, therefore, the masonry is destroyed by tensile forces in the stone arising under the influence of transverse deformations of the mortar. An increase in the thickness of the seam leads to a decrease in the strength of the masonry. The destruction of masonry begins with the opening of vertical seams and the appearance of small vertical cracks in individual stones. With further loading, vertical cracks are connected in height and dissect the masonry into separate pillars, then with a further increase in load, the masonry loses stability.

The strength and deformation characteristics of the masonry are obtained by testing prismatic samples with base dimensions of 38 * 38; 51*51 cm, height 110-120 cm.

Strength characteristics of masonry:-temporary compression resistance R and

Design axial compression resistance R

Design axial tensile strength R bl

Design tensile bending resistance R tb

Design shear resistance R sq

Deformation characteristics of masonry: - elastic modulus of masonry (initial deformation modulus) E o

Elastic characteristic of masonry α

Masonry deformation modulus E

Masonry creep coefficient γ cr

Linear expansion coefficient α t

Friction coefficient μ

The value of R and determined by test data.

R value= R and /k, where k is the coefficient depending on the type of stone; for stone and brick of all types, rubble, rubble concrete k=2; for large and small blocks of cellular concrete k=2.25 (R data are given in SNiP 11-22-81).

When assigning the design compression resistance of masonry, the coefficient of operating conditions is taken into account: γ c - for summer masonry; γ cl – for winter masonry made by freezing

(SNiP 11-22-81 t.33)

Value Rbl; R sq ; Rtb depend on the type of section along which the masonry is destroyed. In this case, it is possible two cases of destruction:- along the untied section, which are the horizontal joints of the masonry

According to the tied section, which are the vertical seams of the masonry, in these cases the section has a stepped shape

The values ​​of R tb R sq R bl are given in SNiP 11-22-81 t. 10

E value under short-term loading is assumed to be equal to E o = α tgφ o, also proportional to the temporary resistance of axial compression E o = α R and

The value of the elastic characteristic α, depending on the type of masonry, for the main types of masonry is found in SNiP 11-22-81

When calculating masonry to constant and long-term loads taking into account creep, the elastic modulus decreases by the creep coefficient γ cr, accepted: 1.2 - for masonry made of ceramic bricks; 1.8 - for ceramics. stones with vertical slotted voids; 2.8 - for masonry from large blocks; 3-for masonry made of sand-lime bricks and concrete blocks with porous aggregates.

E value= tanφ is the tangent of the angle of inclination of the tangent to the curve at a point with a given stress level. The deformation modulus is used in calculations for groups 1 and 11 of limit states of masonry structures. Working in structures together with structural elements made of other materials, with E = 0.5E o

When determining masonry deformations in statically indeterminate frame systems

The moduli of elasticity and deformation of masonry made from natural stones are taken based on the results of experimental studies.

Relative deformation taking into account creep: ε=νσ/ E o, where ν-coefficient, taking into account the influence of creep of the masonry; σ-stress in masonry during long-term loading.

7.1. The requirements of this section apply to the production and acceptance of work on the construction of stone structures made of ceramic and silicate bricks, ceramic, concrete, silicate and natural stones and blocks.

7.2. Work on the construction of stone structures must be carried out in accordance with the project. The selection of the composition of the masonry mortar, taking into account the operating conditions of buildings and structures, should be carried out using reference Appendix 15.

7.3. The brick plinths of buildings must be laid using solid ceramic bricks. The use of sand-lime brick for these purposes is not allowed.

7.4. It is not allowed to weaken stone structures through holes, grooves, niches, or installation openings not provided for in the design.

7.5. The masonry filling of the frames should be carried out in accordance with the requirements for the construction of load-bearing masonry structures.

7.6. The thickness of horizontal joints in masonry made of bricks and stones of regular shape should be 12 mm, vertical joints - 10 mm.

7.7. In case of forced breaks, the masonry must be done in the form of an inclined or vertical cut.

7.8. When breaking masonry with a vertical groove, a mesh (reinforcement) of longitudinal rods with a diameter of no more than 6 mm, of transverse rods - no more than 3 mm with a distance of up to 1.5 m along the height of the masonry, as well as at the level of each floor, should be laid in the joints of the masonry grooves. .

The number of longitudinal reinforcement bars is taken at the rate of one bar for every 12 cm of wall thickness, but not less than two for a wall thickness of 12 cm.

7.9. The difference in the heights of the masonry being erected on adjacent grips and when laying junctions of external and interior walls should not exceed the height of the floor, the difference in height between adjacent areas of foundation laying should not exceed 1.2 m.

7.10. The installation of fasteners at the junction of reinforced concrete structures and masonry should be carried out in accordance with the design.

The construction of stone structures of the next floor is allowed only after laying load-bearing structures floors of the constructed floor, anchoring the walls and sealing the seams between the floor slabs.

7.11. The maximum height for the construction of free-standing stone walls (without laying floors or coverings) should not exceed the values ​​​​specified in Table. 28. If it is necessary to construct free-standing walls of greater height, temporary fastenings should be used.

Table 28

Note. At wind speeds having intermediate values, the permissible heights of free-standing walls are determined by interpolation.

7.12. When erecting a wall (partition) connected to transverse walls (partitions) or other rigid structures with a distance between these structures not exceeding 3.5 N (where H is the height of the wall indicated in Table 28), the permissible height of the wall being erected can be increased by 15%, with a distance of no more than 2.5 N - by 25% and no more than 1.5 N - by 40%.

7.13. The height of unreinforced stone partitions, not supported by ceilings or temporary fastenings, should not exceed 1.5 m for partitions 9 cm thick, made of stones and bricks with an edge thickness of 88 mm, and 1.8 m for partitions 12 cm thick, made of bricks

7.14. When connecting the partition with transverse walls or partitions, as well as with other rigid structures, their permissible heights are accepted in accordance with the instructions of clause 7.12.

7.15. The verticality of the edges and corners of masonry made of bricks and stones, the horizontality of its rows must be checked as the masonry progresses (every 0.5-0.6 m) with the elimination of detected deviations within the tier.

7.16. After finishing the laying of each floor, an instrumental check of the horizontality and marks of the top of the masonry should be carried out, regardless of intermediate checks of the horizontalness of its rows.

MASONRY OF CERAMIC AND SILICATE BRICK, OF CERAMIC, CONCRETE, SILICATE AND NATURAL STONES OF REGULAR SHAPE

7.17. The bonded rows in the masonry must be laid from whole bricks and stones of all types. Regardless of the adopted seam dressing system, laying bonded rows is mandatory in the lower (first) and upper (last) rows of erected structures, at the level of the edges of walls and pillars, in protruding rows of masonry (cornices, belts, etc.).

When multi-row dressing of seams, laying bonded rows under the supporting parts of beams, purlins, floor slabs, balconies, under mauerlats and other prefabricated structures is mandatory. With single-row (chain) ligation of seams, it is allowed to support prefabricated structures on spoon rows of masonry.

7.18. Brick pillars, pilasters and piers two and a half bricks wide or less, ordinary brick lintels and cornices should be built from selected whole bricks.

7.19. The use of half-brick is allowed only in the laying of backfill rows and lightly loaded stone structures (sections of walls under windows, etc.) in an amount of no more than 10%.

7.20. Horizontal and transverse vertical seams of brickwork walls, as well as seams (horizontal, transverse and longitudinal vertical) in lintels, piers and pillars should be filled with mortar, with the exception of empty masonry.

7.21. When laying hollow areas, the depth of the joints not filled with mortar with front side should not exceed 15 mm in walls and 10 mm (vertical joints only) in columns.

7.22. Sections of walls between ordinary brick lintels with walls less than 1 m wide must be laid out on the same mortar as the lintels.

7.23. The steel reinforcement of ordinary brick lintels should be laid along the formwork in a layer of mortar under the bottom row of bricks. The number of rods is established by the project, but must be at least three. Smooth rods for reinforcing lintels must have a diameter of at least 6 mm, end with hooks and be embedded in the piers at least 25 cm. Periodic profile rods are not bent with hooks.

7.24. When maintaining brick lintels in the formwork, it is necessary to observe the terms indicated in Table. 29.

Table 29

7.25. Wedge lintels made of ordinary bricks should be laid with wedge-shaped joints with a thickness of at least 5 mm at the bottom and no more than 25 mm at the top. Laying must be done simultaneously on both sides in the direction from the heels to the middle.

7.26. The laying of cornices should be carried out in accordance with the project. In this case, the overhang of each row of brickwork in the cornices should not exceed 1/3 of the length of the brick, and the total extension of the unreinforced brick cornice should be no more than half the thickness of the wall.

The laying of anchored cornices may be carried out after the masonry wall has reached the design strength into which the anchors are embedded.

When installing cornices after the wall has been laid, their stability must be ensured with temporary fastenings.

All embedded reinforced concrete prefabricated elements (cornices, corbels, balconies, etc.) must be provided with temporary fastenings until they are pinched by the overlying masonry. The term for removing temporary fasteners must be indicated in the working drawings.

7.27. When constructing walls made of ceramic stones in overhanging rows of cornices, corbels, parapets, firewalls, where brick cutting is required, solid or special (profile) facing brick with frost resistance of at least MP325 with protection from moisture must be used.

7.28. Ventilation ducts in the walls should be made of ceramic solid brick of a grade not lower than 75 or silicate brick of grade 100 to the level attic floor, and above - from solid ceramic bricks of grade 100.

7.29. For reinforced masonry, the following requirements must be observed:

• the thickness of the joints in reinforced masonry must exceed the sum of the diameters of the intersecting reinforcement by at least 4 mm with a joint thickness of no more than 16 mm;
• when transversely reinforcing pillars and piers, meshes should be made and laid so that there are at least two reinforcing bars (from which the mesh is made) protruding 2-3 mm onto the inner surface of the pier or on both sides of the pillar;
• when longitudinally reinforcing masonry, steel reinforcement bars along their length should be connected to each other by welding;
• when making reinforcement joints without welding, the ends of the smooth rods must end with hooks and tied with wire with the rods overlapping by 20 diameters.

7.30. The construction of walls made of lightweight brickwork must be carried out in accordance with the working drawings and the following requirements:

• All seams of the outer and inner layers of lightweight masonry walls should be carefully filled with mortar, with the façade joints grouted and internal joints grouted if required. wet plaster wall surfaces from the room side;
• slab insulation should be laid to ensure a tight fit to the masonry;
• metal connections installed in masonry must be protected from corrosion;
• Loose fill insulation or lightweight infill concrete should be laid in layers, compacting each layer as the masonry is built. In masonry with vertical transverse brick diaphragms, voids should be filled with backfill or lightweight concrete in layers to a height of no more than 1.2 m per shift;
• window sill sections of external walls must be protected from moisture by installing ebb tides according to the design;
• During work during periods of precipitation and during breaks in work, measures should be taken to protect the insulation from getting wet.

7.31. The edge of the brick plinth and other protruding parts of the masonry after their construction should be protected from atmospheric moisture, following the instructions in the project, in the absence of instructions in the project - with cement-sand mortar of a grade not lower than M100 and Mrz50.

WALL CLADDING IN THE PROCESS OF MASONRY CONSTRUCTION

7.32. For facing works should be applied cement-sand mortars on Portland cement and pozzolanic cements. The content of alkalis in cement should not exceed 0.6%. The mobility of the solution, determined by the immersion of a standard cone, should be no more than 7 cm, and to fill the vertical gap between the wall and the tile, in the case of fixing the tiles on steel ties, no more than 8 cm.

7.33. When facing brick walls large concrete slabs carried out simultaneously with masonry, the following requirements must be observed:

• cladding should begin with laying a supporting L-shaped row of facing slabs embedded in the masonry at the level of the interfloor ceiling, then installing ordinary flat slabs and fastening them to the wall;
• when the thickness of the facing slabs is more than 40 mm, the facing row should be placed earlier than the masonry is done, at the height of the facing row;
• if the thickness of the slabs is less than 40 mm, it is necessary to first lay the masonry to the height of the slab row, then install the facing slab;
• installation of thin slabs before the construction of the wall is permitted only if fasteners are installed to hold the slabs;
• It is not allowed to install facing slabs of any thickness above the wall masonry by more than two rows of slabs.

7.34. Cladding slabs must be installed with mortar joints along the contour of the slabs or close to each other. In the latter case, the joining edges of the plates must be ground.

7.35. The erection of walls with their simultaneous cladding, rigidly connected to the wall ( face brick and stone, slabs of silicate and heavy concrete), with negative temperatures should, as a rule, be performed on a solution with the antifreeze additive sodium nitrite. Masonry facing with ceramic and sand-lime bricks and stone can be done using the freezing method according to the instructions in the subsection “Construction of stone structures in winter conditions.” In this case, the brand of mortar for masonry and cladding must be at least M50.

FEATURES OF MASONRY OF ARCHES AND Vaults

7.36. The laying of arches (including arched lintels in walls) and vaults must be made of bricks or stones of the correct shape on cement or mixed mortar.

For laying arches, vaults and their heels, Portland cement mortars should be used. The use of slag Portland cement and pozzolanic Portland cement, as well as other types of cements that harden slowly at low positive temperatures, is not allowed.

7.37. The laying of arches and vaults should be carried out according to a project containing working drawings of formwork for laying vaults of double curvature.

7.38. Deviations of the dimensions of the formwork of doubly curvature arches from the design should not exceed: along the lifting boom at any point of the arch, 1/200 of the lift, in terms of the displacement of the formwork from the vertical plane in the middle section, 1/200 of the lifting boom of the arch, in the width of the arch wave - 10 mm.

7.39. The laying of waves of doubly curvature arches must be carried out according to movable templates installed on the formwork.

The laying of arches and vaults should be done from the heels to the castle simultaneously on both sides. Masonry joints must be completely filled with mortar. The upper surface of doubly curvature vaults, 1/4 brick thick, should be rubbed with mortar during the laying process. With a greater thickness of vaults made of brick or stones, the masonry seams must be additionally filled with liquid mortar, while the upper surface of the vaults is not grouted with mortar.

7.40. The laying of doubly curvature vaults should begin no earlier than 7 days after the completion of the installation of their heels at an outside air temperature above 10 °C. At air temperatures from 10 to 5 °C this period increases by 1.5 times, from 5 to 1 °C - by 2 times.

Laying vaults with tie-rods, in the heels of which prefabricated reinforced concrete elements or steel frames, it is allowed to start immediately after finishing the installation of the heels.

7.41. The abutting edges of adjacent waves of doubly curvature arches are maintained on the formwork for at least 12 hours at an outside air temperature above 10 °C. At lower positive temperatures, the duration of keeping the arches on the formwork increases in accordance with the instructions of clause 7.40.

Loading of stripped arches and vaults at air temperatures above 10 °C is allowed no earlier than 7 days after the completion of masonry. At lower positive temperatures, the holding time increases according to clause 7.40.

The insulation on the vaults should be laid symmetrically from the supports to the castle, avoiding one-sided loading of the vaults.

Tensioning of tie rods in arches and vaults should be done immediately after finishing the masonry.

7.42. The construction of arches, vaults and their heels in winter conditions is allowed at an average daily temperature of not lower than minus 15 ° C using solutions with anti-frost additives (subsection “Erection of stone structures in winter conditions”). Wave vaults erected at sub-zero temperatures are kept in the formwork for at least 3 days.

MASONRY FROM ROAD STONE AND ROUGH CONCRETE

7.43. Stone structures It is allowed to build from rubble and rubble concrete using rubble stone of irregular shape, with the exception of external parties masonry for which bedded stone should be used.

7.44. Rubble masonry should be done in horizontal rows up to 25 cm high with trenching of stone on the face of the masonry, crushing and filling the voids with mortar, as well as bandaging the seams.

Rubble masonry with cast mortar filling the seams between stones is allowed only for structures in buildings up to 10 m high, erected on non-subsidence soils.

7.45. When lining rubble masonry with brick or stone of the correct shape simultaneously with the masonry, the lining should be tied with the masonry in a bonded row every 4-6 rows of spoons, but no more than after 0.6 m. The horizontal seams of the rubble masonry must coincide with the dressing bonded rows of the cladding.

7.46. Breaks in the rubble stone masonry are allowed after filling the gaps between the stones of the top row with mortar. Resumption of work must begin by spreading the mortar over the surface of the stones of the top row.

7.47. Rubble concrete structures must be erected in compliance with the following rules:

• laying the concrete mixture should be done in horizontal layers no more than 0.25 m high;
• the size of stones embedded in concrete should not exceed 1/3 of the thickness of the structure being built;
• embedding stones into concrete should be done directly after laying concrete during the process of compaction;
• the construction of rubble concrete foundations in trenches with steep walls can be carried out without formwork;
• breaks in work are allowed only after laying a number of stones in the last (top) layer of the concrete mixture; Resumption of work after a break begins with laying the concrete mixture.
• Structures made of rubble and rubble concrete, erected in dry and hot weather, should be cared for in the same way as monolithic concrete structures.

ADDITIONAL REQUIREMENTS FOR WORK IN SEISMIC AREAS

7.48. Masonry of bricks and ceramic slotted stones must be carried out in compliance with the following requirements:

• masonry of stone structures should be carried out over the entire thickness of the structure in each row;
• masonry of walls should be carried out using single-row (chain) dressing;
• horizontal, vertical, transverse and longitudinal joints of the masonry should be filled completely with mortar, with the mortar trimmed on the outer sides of the masonry;
• temporary (installation) breaks in the masonry being erected should be terminated only with an inclined groove and located outside the areas of structural reinforcement of the walls.

7.49. The use of bricks and ceramic stones with a high content of salts protruding on their surfaces is not allowed.

The surface of brick, stone and blocks must be cleaned of dust and dirt before laying:

• for masonry using conventional mortars in areas with hot climates - with a stream of water;
• for masonry on polymer-cement mortars - using brushes or compressed air.

7.50. At subzero outside temperatures, large blocks should be installed using solutions with antifreeze additives. In this case, the following requirements must be observed:

• before the beginning masonry work the optimal relationship between the amount of pre-wetting of the wall material and the water content of the mortar mixture should be determined;
• conventional solutions must be used with high water-holding capacity (water separation no more than 2%).

7.51. As a rule, Portland cement should be used to prepare solutions. The use of slag Portland cement and pozzolanic Portland cement for polymer cement solutions is not allowed.

To prepare solutions, sand should be used that meets the requirements of GOST 8736-85. Other types of fine aggregates can be used after research into the strength and deformation properties of mortars based on them, as well as the adhesion strength to masonry materials. Sands with a high content of fine-grained clay and dust particles cannot be used in polymer-cement mortars.

7.52. When laying with polymer-cement mortars, the brick should not be moistened before laying, as well as the masonry during the period of curing.

7.53. Monitoring the strength of normal adhesion of the mortar during manual laying should be done at the age of 7 days. The adhesion value should be approximately 50% of the strength at 28 days of age. If the adhesive strength in masonry does not correspond to the design value, it is necessary to stop the work until the issue is resolved by the design organization.

7.54. During the construction of buildings, contamination of niches and gaps in walls, spaces between floor slabs and other places intended for reinforced concrete inclusions, belts and strapping, as well as the reinforcement located in them, is not allowed with mortar and construction waste.

Anti-seismic joints must be freed from formwork and construction debris. It is prohibited to seal anti-seismic joints with bricks, mortar, lumber, etc. If necessary, anti-seismic joints can be covered with aprons or sealed with flexible materials.

7.56. When installing lintel and strapping blocks, it is necessary to ensure the possibility of free passage of vertical reinforcement through the holes provided by the design in the lintel blocks.

CONSTRUCTION OF STONE STRUCTURES IN WINTER CONDITIONS

7.57. Masonry of stone structures in winter conditions should be carried out using cement, cement-lime and cement-clay mortars.

Compound mortar of a given brand (ordinary and with anti-frost additives) for winter work, the mobility of the solution and the period for maintaining mobility are pre-established by the construction laboratory in accordance with the requirements of current regulatory documents and adjusted taking into account the materials used.

For winter masonry, mortars with mobility should be used: 9-13 cm - for masonry made of ordinary bricks and 7-8 cm - for masonry made of bricks with voids and natural stone.

7.58. Masonry in winter time can be carried out using all dressing systems used in the summer. When masonry is done on mortars without anti-frost additives, a single-row dressing should be performed.

With a multi-row dressing system, vertical longitudinal seams are tied up at least every three rows when laying bricks and every two rows when laying ceramic and silicate stone 138 mm thick. Brick and stone should be laid with vertical and horizontal joints completely filled.

7.59. The construction of walls and pillars along the perimeter of the building or within the limits between sedimentary seams should be carried out evenly, avoiding gaps in height by more than 1/2 floor.

When laying blind sections of walls and corners, breaks are allowed to be no more than 1/2 floor high and are made with a fine.

7.60. It is not allowed to lay the mortar on the top row of masonry during breaks in work. To protect against icing and snow drift, the top of the masonry should be covered during breaks in work.

Used in masonry mortars sand should not contain ice and frozen clods, lime and clay dough should not be frozen at a temperature of at least 10 ° C.

7.61. Structures made of bricks, stones of regular shape and large blocks in winter conditions can be erected in the following ways:

• with antifreeze additives in solutions not lower than grade M50;
• using ordinary mortars without antifreeze additives, followed by timely strengthening of the masonry by heating;
• by the method of freezing on ordinary (without antifreeze additives) solutions not lower than grade 10, provided that sufficient bearing capacity of the structures is ensured during the thawing period (at zero strength of the solution).

Masonry with anti-frost additives

7.62. When preparing solutions with antifreeze additives, one should be guided by reference Appendix 16, which establishes the scope and consumption of additives, as well as the expected strength, depending on the time of hardening of solutions in the cold.

When using potash, clay dough should be added - no more than 40% of the mass of cement.

Masonry using mortars without anti-frost additives, followed by strengthening of structures by heating

7.63. When constructing buildings on mortars without anti-frost additives with subsequent strengthening of structures by artificial heating, the procedure for carrying out the work should be provided for in the working drawings.

Table 30

Notes: 1. Above the line is the depth of thawing of masonry (% of wall thickness) made of dry ceramic bricks, below the line is the same, made of silicate or wet ceramic bricks.

2. When determining the depth of thawing of frozen masonry walls heated on one side, the calculated value gravimetric humidity masonry adopted: 6% - for masonry made of dry ceramic bricks, 10% - for masonry made of silicate or ceramic wet (harvested in autumn) bricks.

7.64. Masonry by heating structures must be carried out in compliance with the following requirements:

• the insulated part of the structure must be equipped with ventilation that ensures air humidity during the warm-up period of no more than 70%;
• loading of heated masonry is allowed only after control tests and establishment of the required strength of the heated masonry mortar;
• the temperature inside the heated part of the building in the coolest places - near the external walls at a height of 0.5 m from the floor - should not be lower than 10 °C.

7.65. The depth of thawing of masonry in structures when heated with warm air on one side is taken from Table. thirty; the duration of thawing of masonry with an initial temperature of minus 5 ° C with double-sided thawing - according to > table. 31, when heated from four sides (pillars) - according to table. 31 with data reduction by 1.5 times; strength of solutions hardening at different temperatures - according to table. 32.

Freezing masonry

7.66. By freezing using ordinary (without anti-frost additives) solutions during the winter period, it is allowed, with appropriate calculation justification, to erect buildings with a height of no more than four floors and no higher than 15 m.

The requirements for masonry made by the freezing method also apply to structures made of brick blocks made of positive temperature ceramic bricks, frozen to the set of masonry blocks of tempering strength and unheated until they are loaded. The compressive strength of masonry from such blocks in the thawing stage is determined based on the strength of the solution, equal to 0.5 MPa.

It is not allowed to perform the method of freezing rubble masonry from torn rubble.

7.67. When laying by the method of freezing solutions (without antifreeze additives), the following requirements must be observed:

• the temperature of the solution at the time of its installation must correspond to the temperature indicated in the table. 33;
• performance of work should be carried out simultaneously throughout the grip;
• to avoid freezing of the mortar, it should be laid on no more than two adjacent bricks when making a mile and on no more than 6-8 bricks when backfilling;
• At the mason's workplace, a supply of mortar for no more than 30-40 minutes is allowed. The solution box must be insulated or heated.

Using frozen or thawed hot water solution is not allowed.

Table 31

Notes: 1. When using mortars made with slag Portland cement and pozzolanic Portland cement, one should take into account the slowdown in the increase in their strength at a hardening temperature below 15 °C. The relative strength of these solutions is determined by multiplying the values ​​given in table. 32, by coefficients: 0.3 - at a hardening temperature of 0 °C; 0.7 - at 5 °C; 0.9 - at 9 °C; 1 - at 15 °C and above.

2. For intermediate values ​​of the hardening temperature and age of the solution, its strength is determined by interpolation.

Table 33

Note. For getting required temperature solution, heated water (up to 80 °C), as well as heated sand (not higher than 60 °C) can be used.

7.68. Before the onset of a thaw, before the start of thawing, the masonry should be carried out on all floors of the building all the measures for unloading, temporary fastening or strengthening of its overstressed sections (pillars, piers, supports, trusses and girders, etc.) provided for by the project for the production of work. It is necessary to remove random loads not provided for by the design from the floors ( construction garbage, Construction Materials).

Work quality control

7.69. Quality control of work on the construction of stone buildings in winter conditions should be carried out at all stages of construction.

In the work log, in addition to the usual records of the composition of the work performed, the following should be recorded: the temperature of the outside air, the amount of additive in the solution, the temperature of the solution at the time of laying and other data that affects the hardening process of the solution.

7.70. The construction of a building can be carried out without checking the actual strength of the mortar in the masonry as long as the erected part of the building, according to calculations, does not cause overload of the underlying structures during the thawing period. Further construction of the building is permitted only after the mortar has acquired strength (confirmed by data laboratory tests) not lower than the required calculation specified in the working drawings for the construction of a building in winter conditions.

To carry out subsequent monitoring of the strength of the solution with antifreeze additives, it is necessary to make cube samples measuring 7.07 x 7.07 x 7.07 cm on a water-suction base directly on site during the construction of structures.

When constructing one or two-section houses, the number of control samples on each floor (with the exception of the top three) must be at least 12. If the number of sections is more than two, there must be at least 12 control samples for every two sections.

Samples, at least three, are tested after 3 hours of thawing at a temperature not lower than 20 ± 5 °C.

Control cube samples should be tested within the time frame required for floor-by-floor control of the strength of the mortar during the construction of structures.

Samples should be stored in the same conditions as the structure being built and protected from exposure to water and snow.

To determine the final strength of the solution, three control samples must be tested after thawing in natural conditions and subsequent 28-day hardening at an outside temperature of at least 20 ± 5 ° C.

7.71. In addition to testing cubes, and also in the absence of them, it is allowed to determine the strength of the mortar by testing samples with an edge of 3-4 cm, made from two mortar plates taken from horizontal joints.

7.72. When constructing buildings using the freezing method using ordinary (without anti-frost additives) solutions with subsequent strengthening of the masonry by artificial heating, it is necessary to constantly monitor temperature conditions hardening the solution and recording them in a journal. The air temperature in the rooms during heating is measured regularly, at least three times a day: at 1, 9 and 17 o'clock. The air temperature should be monitored at least 5-6 points near the external walls of the heated floor at a distance of 0.5 m from the floor .

The average daily air temperature in the heated floor is determined as the arithmetic average of individual measurements.

7.73. Before the approach of spring and during the period of prolonged thaws, it is necessary to strengthen control over the condition of all load-bearing structures of buildings erected in the autumn-winter period, regardless of their number of storeys, and develop measures to remove additional loads, install temporary fasteners and determine conditions for further continuation of construction work.

7.74. During natural thawing, as well as artificial heating of structures, constant monitoring of the magnitude and uniformity of wall settlement, the development of deformations of the most stressed sections of the masonry, and the hardening of the mortar should be organized.

Observation must be carried out throughout the entire hardening period until the solution reaches the design (or close to it) strength.

7.75. If signs of overstressing of the masonry are detected in the form of deformation, cracks or deviations from the vertical, urgent measures should be taken to temporarily or permanently strengthen the structures.

Strengthening of stone structures of reconstructed and damaged buildings

7.76. Work to strengthen the stone structures of reconstructed and damaged buildings is carried out in accordance with the working drawings and the work project.

7.77. Before strengthening stone structures, the surface should be prepared: visually inspect and tap the masonry with a hammer, clean the surface of the masonry from dirt and old plaster, remove partially destroyed (thawed) masonry.

7.78. Reinforcement of stone structures by injection, depending on the degree of damage or the required increase in the load-bearing capacity of structures, should be performed using cement-sand, sandless or cement-polymer mortars. For cement and cement-polymer mortars, it is necessary to use Portland cement grade M400 or M500 with a grinding fineness of at least 2400 cm 3 /g. The cement paste should be of normal thickness within 20-25%.

When preparing an injection solution, it is necessary to control its viscosity and water separation. Viscosity is determined using a VZ-4 viscometer. It should be 13-17 s for cement mortars, 3-4 min for epoxy mortars. Water separation, determined by holding the solution for 3 hours, should not exceed 5% of the total volume of the mortar mixture sample.

7.79. When reinforcing stone structures with steel clips (angles with clamps), installation metal corners should be done in one of the following ways:

first - a layer of cement mortar of a grade not lower than M100 is applied to the reinforced element in the places where the corners of the frame are installed. Then install the corners with clamps and create a pre-tension in the clamps with a force of 10-15 kN;

second - the corners are installed without mortar with a gap of 15-20 mm, fixed with steel or wooden wedges, and a tension of 10-15 kN is created in the clamps. The gap is caulked with a rigid solution, the wedges are removed and the clamps are fully tensioned to 30-40 kN.

With both methods of installing metal clips, the clamps are fully tensioned 3 days after they are tensioned.

7.80. Reinforcement of stone structures with reinforced concrete or reinforced mortar clips should be carried out in compliance with the following requirements:

Reinforcement should be performed with connected frames. The reinforcement frames must be fixed in the design position using staples or hooks driven into the masonry joints in increments of 0.8-1.0 m in a checkerboard pattern. It is not allowed to connect flat frames into spatial frames by manual spot welding;

collapsible formwork should be used for formwork, formwork panels must be rigidly connected to each other and ensure the tightness and invariability of the structure as a whole;

lay the concrete mixture in even layers and compact it with a vibrator, avoiding damage to the solidity of the reinforced section of the masonry;

the concrete mixture should have a cone draft of 5-6 cm, the crushed stone fraction should not exceed 20 mm;

stripping of the clips should be carried out after the concrete reaches 50% of the design strength.

7.81. When reinforcing stone walls with steel strips in the presence of a plaster layer, it is necessary to make horizontal strokes in it with a depth equal to the thickness of the plaster layer and a width equal to the width of the metal strip 20 mm.

7.82. When reinforcing stone walls with internal anchors, it is necessary to inject holes in the wall under the anchor with a solution.

The main anchor holes should be placed in a checkerboard pattern with a step of 50-100 cm with a crack opening width of 0.3-1 mm and 100-200 cm with a crack opening of 3 mm or more. In places of concentration of small cracks, additional wells should be located.

Wells must be drilled to a depth of 10-30 cm, but not more than 1/2 the thickness of the wall.

7.83. When reinforcing masonry walls with prestressed steel ties, the exact tensile strength of the ties should be controlled using a torque wrench or by measuring strains with a dial indicator with a division value of 0.001 mm.

When installing strands in winter in unheated rooms, it is necessary to tighten the strands in summer, taking into account the temperature difference.

7.84. Replacement of piers and pillars with new masonry should begin with the installation of temporary fastenings and dismantling window fillings in accordance with working drawings and work design. The new laying of the pier must be carried out carefully, with a dense upsetting of the brick to obtain a thin seam.

The new masonry should not be brought closer to the old one by 3-4 cm. The gap should be carefully caulked with a rigid solution of a grade of at least 100. Temporary fastenings can be removed after the new masonry reaches at least 70% of the design strength.

7.85. When strengthening masonry, the following are subject to control:

• quality of masonry surface preparation;
• compliance of reinforcement structures with the design;
• quality of welding of fasteners after stressing structural elements;
• availability and quality of anti-corrosion protection of reinforcement structures.

Acceptance of stone structures

7.86. Acceptance of completed work on the construction of stone structures must be carried out before plastering their surfaces.

7.87. Elements of stone structures hidden during construction and installation works, including:

• places where trusses, purlins, beams, floor slabs are supported on walls, pillars and pilasters and their embedding in masonry;
• fastening in prefabricated masonry reinforced concrete products: cornices, balconies and other cantilever structures;
• embedded parts and their anti-corrosion protection;
• reinforcement laid in stone structures;
• sedimentary expansion joints, anti-seismic joints;
• water vapor barrier of masonry;
• should be accepted according to documents certifying their compliance with the design and regulatory and technical documentation.

7.88. When accepting completed work on the construction of stone structures, it is necessary to check:

• the correctness of the dressing of the seams, their thickness and filling, as well as the horizontality of the rows and the verticality of the corners of the masonry;
• correct construction of expansion joints;
• correct installation of smoke and ventilation ducts in the walls;
• quality of surfaces of façade unplastered brick walls;
• quality of facade surfaces lined with ceramic, concrete and other types of stones and slabs;
• geometric dimensions and position of structures.

7.89. When accepting stone structures made in seismic areas, the device is additionally controlled:

• reinforced belt at the level of the top of the foundations;
• floor-by-floor antiseismic belts;
• fastenings thin walls and partitions to main walls, frames and ceilings;
• strengthening stone walls by including monolithic and prefabricated reinforced concrete elements in the masonry;
• anchoring of elements protruding above the attic floor, as well as the strength of adhesion of the mortar to the wall stone material.

7.90. Deviations in the size and position of stone structures from the design ones should not exceed those indicated in > table. 34.

Table 34

Note. The dimensions of permissible deviations for structures made of vibrated brick, ceramic and stone blocks and panels are given in parentheses.