Rules for the installation of prefabricated concrete and reinforced concrete structures. Ways and methods of installation of prefabricated reinforced concrete structures. Installation of foundation blocks and walls of the underground part of the building

Precast concrete structures are manufactured in factories and only then delivered to the construction site. On the one hand, due to the scaling of production, this can significantly reduce the cost of a unit of production, on the other hand, the designer must set clear parameters for the future product.

Prefabricated reinforced concrete structures make it possible to erect entire buildings in the shortest possible time, but the possibility of modifying products during operation is extremely limited and is associated with considerable financial costs.

There are types reinforced concrete structures, which are made only in factories. An example is prestressed FLC. Typically, enterprises produce only standard products. Of course, it is possible to order individual parameters, but you have to pay extra for uniqueness. Conventionally, all production technologies can be divided into three types:

• conveyor technology,
• flow-aggregate technology,
• bench technology,

For prestressed prefabricated structures, the following production methods are used: tension on concrete and tension on supports. The armature is tensioned by electromechanical and electrothermal methods.

General characteristics

The characteristics of precast concrete structures depend on the type of concrete and the type of reinforcement used in them. Concrete has the following quality parameters:

• frost resistance,
• strength,
• high density,
• fire resistance.

The only disadvantage of concrete is its poor tensile strength. To level it, reinforcement is used. It can be made from composite or steel. The shape can be different, but in most cases ribbed steel rods with a round section are used.

Mounting process

At the beginning of the installation, the condition of the already installed precast concrete structures is checked. The further algorithm of the process directly depends on the type of FLC and the goals pursued by the builders. Nevertheless, there are points that are always present in the work:

1. Inspection of precast concrete structures to be installed. Builders must ensure that embedded parts are positioned correctly and anti-corrosion coating not damaged. Particular attention is paid to the reinforcement, it must not be damaged or deformed.
2. Design and mounting holes are checked. Their diameter must correspond to the indicators in the project. For measurements, a tape measure or meter is used.
3. Precast concrete structures are examined for cracks and pits. geometric shape products must comply with the design.
4. After inspection, all precast concrete structures are cleaned. Parts deformed during transportation are straightened out. The influx of concrete is removed and rust is removed (if any).

Prefabricated reinforced concrete structures can be slinged during installation different methods. Lifting means can be in the form of traverses, flexible slings or vacuum grips.

Advice ! It is most convenient to work with lifting devices that have a detachable remote hook.

SNiP 52-01-2003 as amended in 2012

SNiP is a set of rules that includes a set of norms and recommendations regarding the production, design, installation and transportation of precast concrete structures.

Prefabricated reinforced concrete structures, despite high strength, must be transported according to established standards. When an FLC is designed, the impact of the forces that arise during lifting, transportation and installation is taken into account. In this case, the load depends on the mass and is calculated using the following coefficients:

• 1.4 - for installation;
• 1.6 - for transportation;
• 1.25 is the coefficient of dynamism.

The last indicator is an illustration of the boundary figure, below which the coefficient in the calculations cannot fall. Otherwise, the reliability and durability of the precast concrete structure will become questionable.

Nodal and butt elements play a special place in the process of designing precast concrete structures. It depends on their quality performance characteristics the entire assembly structure.

In precast concrete structures big role loops play. When creating them, according to SNiP 52-01-2003, it is customary to use hot-rolled reinforcing steel. At the same time, its class must be at least A240.

Important ! During the creation of loops for SZhK, the use of St3ps steel is unacceptable.

If you have ever dealt with monolithic reinforced concrete structures, then you know very well that they cannot be mounted when sub-zero temperature without special equipment. SLC are deprived of such a disadvantage. According to SNiP, they can be mounted when it is -40 outside. This will in no way affect their performance.

Characteristics of precast concrete structures according to SNiPs

Reinforcement plays a special role in the characteristics of precast concrete structures. To achieve an optimal result, it is necessary to accurately calculate the distance from the rod to the rod and the diameter of the reinforcement itself. It is very important that the steel elements completely hide the concrete. There are specific cover options for each type of building:

1. The humidity level is medium or low, the type of room is closed - a protective layer of at least 15 mm.
2. At high humidity indoors - 20 mm.
3. Outdoors - 25 mm.
4. In the ground and foundation - 35 mm.

To achieve the desired quality indicators, it is necessary that prefabricated reinforced concrete structures meet these characteristics. Reducing the protective layer of concrete is possible only if there is additional measures protection.

If the precast concrete structure does not have a reliable protective layer for the reinforcement, then there is a high risk that corrosion will reach the precast structure. This compromises the strength of the entire building.

Installation requirements according to SNiPs

During the construction of a building from FLC, the role of the designer increases many times over. It is he who, with the help of special programs, must calculate in advance the parameters of the future structure. According to these characteristics, products of the desired shape and size will be manufactured at the plant.

Installation must take place strictly according to the approved plan. This document provides for the sequence of work and additional measures to ensure the required strength. Prefabricated reinforced concrete structures are assembled directly at the facility and installed in the place assigned to them in the project.

Testing the characteristics of SZhK according to SNiPs.

Before sending the product to the customer or putting it on stream, a whole complex of complex tests is carried out. The following characteristics are tested during the process:

• crack resistance;
• serviceability;
• overall fitness score.

Testing takes place by changing the load on the precast concrete structure. In some cases, blocks are deliberately destroyed in order to find out the ultimate strength values.

Usually several products are taken from a batch, and they are amenable to different kind tests. The choice of the latter largely depends on the purpose of prefabricated reinforced concrete structures. The suitability assessment consists of indicators such as:

• protective layer thickness;
• strength of welded joints;
• the geometric size of the sections and the location of the reinforcement;
• strength of welds;
• mechanical properties of reinforcement;
• product size.

Based on these indicators, an assessment of the entire batch is formed, and a decision is made regarding its suitability.

Results

Prefabricated reinforced concrete structures are manufactured only in factories. At one time, this gave a significant impetus to the general industrialization of industry. FLC can be mounted in any weather, and their cost is at an affordable level.

During the installation of buildings, structures and technological equipment use cranes for supplying elements to their installation site. When erecting building structures, stationary mounting machines that allow work in a strictly defined space: mounting booms, mounting masts, chevres (a type of masts), portal hydraulic and cable lifts, screw mast-jib cranes, stiff-legged mast-jib cranes, attached tower cranes. mobile assembly machines are able to move from parking lot to parking lot on their own: crawler, wheeled and tower cranes.

Load gripping devices are shown in fig. 9.1 and 9.2.

Depending on the laying height of the structure, there are various methods installation of structures: building up, growing, turning with sliding, turning, sliding, etc. The sequence of installation of elements in the design position determines the following installation methods: element-by-element, differentiated, complex and mixed. Installation of structures can be carried out from the object warehouse or directly from Vehicle("mounting from wheels"). For the installation of pipelines from individual pipes or their short sections, self-propelled jib cranes on caterpillar, automobile and pneumatic wheels are used. For the installation of pipes from long sections and lashes, the main machines are pipe-laying cranes with a side boom and a folding counterweight.

Choice of mounting cranes. The selection of a crane is usually carried out in two stages. At the first stage, the minimum possible operating parameters of the crane required for the given conditions and the accepted schemes of installation work are determined - hook reach, lifting height (lowering depth into the trench) of the hook and load capacity. At the second stage, technical and economic indicators are calculated for each of the selected cranes and the most economical one is determined from them.

Rice. 9.1.1 - carbine;

• 2- hook; 3- traverse; 4 - cable; 5- electric grip; 6- thimble;
• 7 - lightweight sling; 8- universal sling; 9- linings;
• 10 - column; 11 - suspension; 12- gripping cheeks; 13- frame;
• 14- lever; 15- movable shaft; 16- clamping shoes;
• 17- safety chains

Calculation of operating parameters for the selection of a crane. First, the minimum hook reach is determined - the smallest distance from the axis of rotation of the crane turntable (for pipe-laying cranes - from the extreme caterpillar) to the axis of the pipeline in the trench. The required hook reach T to the mounting crane, depending on the adopted pipeline installation scheme (Fig. 9.3), can be determined by the following formulas and dependencies.

When laying pipelines from single pipes in trapezoidal trenches according to the scheme shown in fig. 9.3, a, b k = 0,5(b + B cr) + 1.2 tk, where b- trench width along the bottom, m; B cr - width of the crane base, m; 1.2 ti - the distance from the base of the excavation slope to the caterpillars (wheels or outriggers) of the crane (the free berm must be at least 1 m); t- laying of slopes; /? - trench depth, m

Rice. 9.2. Lifting devices used in the construction of pipelines: a - slinging pipes with a universal sling with a device for slinging; b - semi-automatic sling "noose"; in - slinging the pipe with this sling; g, d- two- and four-branch slings with end grips for pipes; e - slinging steel pipe two-branch sling; w - articulated end grip for asbestos-cement pipes; h- mounting bracket for reinforced concrete pipes; and - the same for ceramic; 1 - cable; 2- latch-lock; 3- cheeks; 4- base plate;

• 5 - finger; 6 - cable (sling); 7 - pipe; 8 - bracket; 9 - capture; 10 - thimble; 11 - earring; 12- soft pads; 13- suspension device;
• 14 - mounting bracket

When installing pipelines from single pipes in rectangular trenches with fasteners (Fig. 9.3, b), the hook reach is determined similarly.

For the installation of pipelines from large assembly blanks (up to 18-24 m long), the hook overhang is taken as low as possible, but in such a way that the crane operating conditions are the most favorable (Fig. 9.3, c), b k = 0,5b + 1,2 tk + c1 n + 1 + 0.5B cr, where with! and - outside diameter laid pipes, and for socket pipes- socket diameter, m.

In deep trenches, as well as in soft soils, pipes are laid with a long hook reach. In this case, if the distance from the axis of rotation of the crane to the center of gravity of the pipe section is less than the hook projection required by the calculation (b 2 then the installation scheme is left the same (Fig. 9.3, in), and if C > b K, then the crane is moved away from the section to the side at a distance of at least 1 m and fed forward by an amount b 2 -b k, carrying out further installation at the calculated hook reach (determined by the above formula). During installation, in this case, guys are applied to the ends of the pipe section to prevent it from turning when lifting. When such a shift is not possible due to local or other conditions, the installation is carried out and the crane is selected with a hook departure equal to b 2 b k = b 2 = 0.5 4r. c + 1.5 + / gab, where / trs - the length of the pipe section; 1.5 m - clear distance between the end of the section and the clearance of the crane (according to safety conditions); 4.6 - the distance between the axis of rotation of the crane platform and the front edge of its running gear.

When installing pipes from vehicles (Fig. 9.3, G) the hook overhang is determined by a formula similar to the one given, and checked by the condition: b^=/) + 1 + B a, where D. p is the distance between the axes of movement of the crane and vehicles; /) - turning radius of the tail part of the crane platform; B a - the width of the vehicle base.

This simultaneously determines the location of the vehicles in relation to the crane. Distance between the axis of rotation of the crane and the center of gravity of the delivered pipe (section) (b pn):

Laying insulated braided steel pipes in field conditions usually lead by pipe-laying cranes. Based on the condition of preventing the collapse of the trench wall, the distance from the crest to the pipe-laying crane should be at least 2 m. The required reach of the pipe-laying crane hook b K -0.5b + ti + 2 m

If the laying of insulated lashes is carried out by jib cranes on caterpillar or pneumatic wheels, then they are placed on the other side of the lash (counting from the trench), and the required reach then b to = 0,5b + u + 4„1 + with! and +/ br2 + 0.5B kr, where / br1, / br2 - respectively, the distance from the edge of the trench to the pipe lash and from it to the crane. Usually they take / brb \u003d 1 m, and / br2 \u003d 0.5-1 m.

Crane lifting capacity calculated based on the maximum load that the crane must lift with the required hook reach b k.

It is determined by the mass of the mounted pipes or their sections and lashes, taking into account the mass lifting devices. According to the directories, the appropriate types and brands of cranes are selected. When two cranes are working, the calculation is carried out on one of them. The main technical and economic indicators are: the duration and complexity of installation; the cost of installation work per unit of construction.

Rice. 9.3. Scheme for determining the hook outreach when laying pipes: a - laying single pipes in trapezoidal trenches; b - the same in trenches with fasteners; in - the same with a link length of more than 12 m;

g - when mounting "from the wheels"

The choice of lifting devices (slings, clamps, brackets, traverses, suspensions, etc.) for lifting, moving and laying pipes is carried out on the basis that they meet the following basic requirements: ensuring the necessary carrying capacity; strength; reliable fastening (slinging) of the pipe; inadmissibility of damage to both the pipe itself and its insulating coating; simplicity of design and application.

PROJECT OF WORK PRODUCTION
for the installation of prefabricated reinforced concrete structures of the "cube 2.5" system

1. General part

1. General part

1.1 This project for the production of works was developed for the installation of prefabricated reinforced concrete structures of the "cube 2.5" system at the facility: "Residential development in the Yugo-Zapadny microdistrict". Buildings N 13, 14, 15. Address: Moscow region, Podolsk.

2. Technological sequence of works

2.1 General data

The frame of the KUB-2 5 system is intended for use in residential buildings and public buildings as well as in ancillary buildings industrial enterprises with the number of floors up to 15 inclusive.

The frame is assembled from prefabricated products with subsequent monolithic nodes.

The frame of the KUB-2.5 system is designed according to a frame or frame-and-frame scheme, the transfer of horizontal forces to the columns and stiffeners is ensured by monolithic floor panels with their transformation into HDD in the horizontal plane.

Load bearing capacity ceilings allows the use of the frame in buildings with an intensity of loads per floor of not more than 1300 kg / m.

The developed frame structures provide for floor heights in buildings of 2.8 m, 3.0 m and 3.3 m with the main column grid of 6.0x6.0 m. For buildings with a height of more than 15 floors, it is necessary individual development columns.

In the KUB-2.5 system, reinforced concrete compressed-tensioned braces in an ascending pattern were adopted, which ensured spatial rigidity and stability of the frame-bonded version of the system. The bearing capacity of the connection element is determined from the calculation of its work on the longitudinal tensile force.

The section of the element of connections is taken 200x250 mm, reinforcement with 4 bearing reinforcing bars, both ends of which are welded to the embedded loops located at both ends of the element.

2.2 Installation of columns and ties

2.2.1 Preparatory work

Before starting the installation of columns on the foundation, it is necessary to perform the following work:

To make monolithic foundations of glass type, to check the accuracy of the execution of glasses of their binding to the axes of the building. Completed designs are accepted according to the act;

Carry out the preparation of the basement floor;

Make sure that the foundation concrete has gained 70% of the design strength.

Before starting the installation of subsequent columns, the following work must be done:

Install floor guard. Close the openings in the ceilings with wooden shields;

Check the correct installation of the underlying columns and accept them according to the act;

Prepare the necessary mounting equipment;

Concrete monolithic structures(seams) of the underlying columns and floors should gain 70% of the design strength.

2.2.2 Work sequence

2.2.2.1 Work on the installation of columns on the foundation is carried out in the following sequence:

Rinse the glass with water under pressure and make a gravy from cement mortar M-200, the top of which must correspond to the design mark of the bottom of the column;

After the column is fed to the foundation glass, the installers approach it, calm it down from vibrations and lower it into the glass. If the height of the column from the edge of the glass does not exceed 12 cm, then fixing it with wedges from buckling can be considered sufficient; if this size exceeds 12 cm, then it is necessary to install special struts, which are removed after installation and monolithic of the first floor. During the installation of the column, it is necessary to ensure that the longitudinal risks are located in relation to the enclosing structures adjacent to them according to Figure 2;

Using longitudinal marks on the sides of the column, align it vertically and horizontally and then fix the column with 4 steel wedges;

Concrete the sinuses in the glass with fine-grained concrete B25, followed by compaction;

For the installers, install the Aris tower 1x1.5x9.6 m (it is possible to replace it with similar ones in terms of characteristics) and install the telescopic struts to the column. Fasten the second end of the struts to the ceiling with anchor bolts;

Fig.1. Scheme of fixing the column with wedges

Fig.2. Scheme of the location of longitudinal scratches in relation to adjacent structures

2.2.2.2 Installation of columns on top of each other is carried out in the following sequence:

At the storage site, insert a trunnion into the through hole of the column at the level of the upper tier and fix it with pins. Tie a rope to the trunnion and stud (for bridging after mounting the columns). Attach the rope to the column. Install a clip on the column (for attaching telescopic struts) below the mark for the bottom of the overlap with the ribs down;

At the signal of the slinger, move the column to the installation site, while the installers must be outside the danger zone formed from the fall of the column;

After the column has been delivered to the installation site, the installers will approach it and calm it down from vibrations. Align the columns one above the other and lower, while the rod of the lower end of the upper column must enter the branch pipe of the upper end of the lower column. Next, it is worth welding the reinforcement according to the project;

For the installers, install the Aris tower 1x1.5x9.6 m (it is possible to replace it with similar ones in terms of characteristics) and install the telescopic struts to the column. Fasten the second end of the struts to the floor with anchor bolts. The braces may only be removed after the installation of the overlying floor slabs;

After mounting the column, untie it by pulling the pin out of the trunnion and pulling the trunnion out of the column with a rope.

2.2.2.3 Installation of column ties is carried out in the following sequence:

At the storage site, perform a preliminary pairwise assembly of the connection elements into a triangle using a mounting spacer;

Perform welding of support tables to the column;

At the signal of the slinger, apply the connection to the installation site, while the installers must be outside the danger zone formed from the fall of the connection. Reinforced concrete ties are installed "herringbone" in an ascending pattern;

After submitting the connection to the installation site, installers approach it and calm it down from vibrations. Set the connection on the tables and weld;

Concrete the supporting structures with fine-grained concrete B15 within the sectional dimension of the element.

Fig.3. Appearance columns and its nodes

Fig.4. Column connection node

Fig.5. Ties attachment point

2.3 Installation of floor slabs

2.3.1 General data

Floor panels are designed in 2 modifications: single-module with maximum dimensions 2980x2980x160 and two-module - 2980x5980x160. At the ends of the panels there are hinged outlets, which provide a monolithic connection of adjacent panels in the building frame, and mounting tables, which in most cases provide installation of the ceiling without supporting racks.

Single-module floor panels are divided, depending on their location in the frame, into above-column (panels directly supported by columns) NP - inter-column (panels located between above-column) MP - and middle (located between annular) SP.

2.3.2 Preparatory work

Before installing floor panels, make sure that:

Distances between columns correspond to design values ​​within tolerances;

Geometric dimensions of panels (diagonal dimensions, "propeller ratio", etc.), reinforcing outlets, embedded parts, etc. meet design requirements;

There are no technological influxes of concrete that interfere with installation and welding.

2.3.3 Work sequence

The installation option for 2 modular panels provides for the following sequence:

Installation of a 1-module above-column panel NP;

Installation of a 2-module NMP panel;

Installation of a 2-module MSP panel;

Fig.6. Mounting option for 2-module panels

The installation option for I-modular panels provides for the following sequence:

Installation of the above-column panel NP;

Installation of the intercolumn panel MP;

Installation of the middle panel of the joint venture;

Fig.7. Mounting option for I-modular panels

2.3.3.1 Installation of panels is carried out in the following sequence:

Install a mounting jig on the column;

At the signal of the slinger, move the NP slab to the installation site, while the installers must be outside the danger zone formed from the fall of the slab;

After the slab is delivered to the installation site, the installers should approach it, calm it down from vibrations and lower it onto the conductor;

Adjust the level of the panel using specialized bolts on the conductor;

Install telescopic racks under the stove;

Attach the NP panel to the column by welding the shell of the plate with the working reinforcement of the column. After doing welding work it is allowed to remove the conductor;

In the places of installation of inter-column ties, weld the top of the triangle to the shell of the ties of the structural panel;

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The topic of this article is reinforced concrete load-bearing and enclosing structures. We have to deal with their classifications and get acquainted with the requirements for installation work set out in the current regulatory documents.

Construction industrial building. Floor slabs - reinforced concrete, load-bearing frame - steel.

Classification

What types of reinforced concrete structures are used in construction?

• Monolithic. Most good example- modern frame-monolithic apartment buildings. The load-bearing frame of the building is cast on site in a removable formwork; after the concrete has gained strength, enclosing walls and partitions are erected from light porous materials.
• prefabricated. An example of such a design is panel house: it is built from finished elements. The installation of precast concrete structures, as a rule, comes down to combining the frame reinforcing the structural elements by welding and concreting the joints.

Useful: this technology, among other things, allows the use of structural elements with prestressed reinforcement.
The reinforcing rods heated by high currents, cooling down, stretch and thereby increase the bending strength of the product.
The method of producing reinforced concrete with reinforcement tension implies industrial conditions.

• Prefabricated - monolithic. This type of structure includes, for example, a ceiling made of slabs laid on monolithic crossbars.

Typical combined design. 1 - monolithic columns; 2 - floor slabs; 3 - monolithic crossbars; 4 - external walls of aerated concrete blocks.

In addition, during the construction of buildings and industrial facilities, dissimilar elements can be combined into a single structure. The joint installation of reinforced concrete and steel structures is used, for example, when creating open warehouses adjacent to a building: beams or canopy trusses are welded to embedded parts in concrete or anchored to a monolith.

Regulations

What documents regulate the installation of reinforced concrete products?

We will have to familiarize ourselves mainly with the content of the last document: it contains the most full information for installation work.

SNiP 3.03.01-87

The document applies to the following list of works:

• Construction of monolithic concrete and reinforced concrete walls, beams, columns, ceilings and other load-bearing and enclosing structures.

Monolithic housing construction is one of the special cases of SNiP application.

• Installation of reinforced concrete and metal structures prefabricated type in the conditions of a construction site.
• Welding field connections metal structures, welding of reinforcement joints reinforced concrete products and embedded parts in them.
• Construction of stone, ceramic, silicate and concrete blocks.

The work begins with the preparation of a PPR (project for the production of works). The project, among other things, should include a statement of the order of the main operations, taking into account the safety and manufacturability of construction.

All materials used must comply with applicable standards and/or specifications.

Let's study the basic requirements of SNiP.

Warehousing and moving

During storage, structural elements must be supported by rectangular spacers with a thickness of at least 30 millimeters. When stacking, the spacers should be in the same vertical line.

Armature outlets are protected from damage. Surfaces provided with a texture to ensure better adhesion to concrete also require protection.

Warehousing is carried out taking into account the order of installation. In this case, the factory marking must remain visible.

Metal fasteners (bolts, nuts, etc.) are stored exclusively indoors; they must be sorted by standard sizes, strength class, and in the case of high-strength products - also by batches.

Moving any products by dragging is prohibited. Lifting equipment is used to move or feed to the place of work. Slinging is carried out for mounting loops or in the places indicated in the working drawings.

Let's clarify: ENiR for installation and construction works(document containing uniform norms and prices) is based on the movement of goods weighing up to 50 kg at a distance of up to 30 meters with your own hands, without the use of loading equipment.

The slinging method must exclude the displacement of the slings and damage to the reinforcement. It is forbidden to rafter products for the release of reinforcement. The position of the element during lifting should be as close as possible to the design (that is, for example, Wall panel delivered to the place of work in vertical position, and the floor panel is horizontal).

Elements rise without jerking and swinging; the desired orientation in space is achieved by using braces (one for vertically oriented elements and at least two for horizontal parts of the structure).

The ascent is done in two steps:

1. The product rises by 20-30 cm to check the quality of the slinging.
2. After verification, further ascent is carried out.

The method of fixing the elements should exclude their displacement at any stage of installation. Before secure fixation (permanent or temporary), the product must not be used as a support for others. structural elements.

Concrete works

According to SNiP, mixtures prepared in accordance with the following requirements should be used for them:

Dosing of concrete components is carried out by weight. According to the volume of water for mixing, only modifying additives (plasticizers, antifreeze, etc.) can be dosed.

The ratio of components is determined separately for each batch of cement and aggregate with mandatory control of samples for mobility and strength.

It is forbidden to increase the mobility of concrete by introducing water into it.

Before concreting, the surfaces of working joints must be cleaned of dirt, dust, debris, grease stains, cement film, snow and ice. Immediately before the concrete is placed, the surface is washed with water and dried with a stream of air. The instruction is associated with a decrease in the adhesion of cement to the base when the surface is contaminated.

Concrete is laid in horizontal layers of equal thickness.

When vibrating, the vibrator must not rest on reinforcement, embedded parts or formwork. The deep vibrator should be immersed 5-10 cm into the previously laid layer and move in increments of no more than one and a half radius of action; the superficial one moves with a 10 cm overlap of the vibrated area.

Laying the next layer of concrete is permissible either before the previous layer has set, or after it has gained strength of at least 1.5 MPa. The same strength is required so that the concrete can be walked on or the formwork of the overlying part of the structure can be installed.

Concrete processing

It may include cutting expansion joints, openings and technological openings.

• For all work, SNiP provides for the use of diamond tools. It is quite natural: despite the fact that its price is quite high, cutting reinforced concrete diamond circles is cheaper than the same work performed by conventional abrasives. The reason is the huge difference in wear rate.

Useful: In addition, diamond drilling holes in concrete, in contrast to the use of pobedit drills and crowns, makes the edges of the hole perfectly even.

• The tool is cooled by water with the addition of surfactants, which reduce energy losses to overcome friction.
• The strength of concrete at the time of processing should reach at least 50% of the design.

Reinforcement

Non-weld connections of reinforcing bars are made using annealed binding wire. For butt joints, the use of crimp sleeves and screw couplings is allowed.

It is preferable to use large-block reinforcing products or factory-made meshes.

When installing reinforcement, it is necessary to maintain the thickness of the protective layer of concrete, excluding contact of the reinforcement with atmospheric air and water.

prefabricated structures

How does the document regulate the installation of prefabricated concrete and reinforced concrete structures?

• In the general case, the next tier of a multi-tier structure is erected not only after the reinforcing frames are joined by welding, but also after the seams are sealed and concrete sets the strength specified in the PPR. Exceptions are specifically stipulated in the project.

Panel housing construction is one of the few exceptions. The seams are closed last.

• Temporary mounting ties can be used to secure the structural element during assembly. Their number, type and procedure for application are again specified in the PPR.
• For concreting joints, it is not allowed to use a solution that has begun to set. The consequence of violating this rule is a catastrophic drop in the compressive strength of the assembly seam.
• Crossbars, load-bearing trusses, inter-column slabs and rafter beams are laid dry on the supporting surfaces of the columns, without mortar. Floor slabs are laid on the mortar; the thickness of its layer should not exceed 20 mm. The surfaces of adjacent slabs are aligned from the side of the ceiling.
• When installing ventilation units, it is necessary to control the filling of horizontal joints with mortar. There should be no gaps.
• Sanitary cabins are placed on gaskets with the alignment of the vertical axis of the risers. Holes for risers are sealed after pressure testing of hot and cold water supply systems.

In the photo - a reinforced concrete sanitary cabin.

• For embedding the joints of prefabricated reinforced concrete structures, concretes based on fast-hardening Portland cements (grade M400 and higher) are used. The use of hardening accelerators is allowed and even recommended. The maximum aggregate grain size in concrete should not exceed 1/3 of the minimum joint section and 3/4 of the minimum distance between reinforcement elements.
• At the time of formwork removal, concrete must reach the minimum strength specified in the project.

Please note: in the absence special instructions stripping is carried out after reaching 50% of the nominal strength.

• During the installation of welded steel structural elements, shock effects on them are prohibited during low temperatures. To be precise, for steels with a yield strength of 390 MPa or less, the lower temperature limit is -25 ° C, and for steels with a yield strength of more than 390 MPa - 0 degrees.

Conclusion

We hope that the information provided to the reader will be useful. The video in this article, as usual, contains additional materials on the topics we are discussing. Successes in construction!