Technical map of a monolithic floor slab. TTK. Installation and dismantling of monolithic floor slab formwork. Basic instructions for concreting floors

CONCRETE PLOCKING OF A TYPICAL FLOOR OF A MONOLITHIC BUILDING

1 AREA OF USE

1.1. A standard technological map (hereinafter referred to as TTK) was developed for a complex of concrete works during laying concrete mixture into floors using a concrete pump with transportation of concrete mixture by concrete mixer trucks during the construction of a residential building. Floor height up to 2.5 m, floor thickness up to 180 mm.

It is planned to support the continuous floor slab along the perimeter on load-bearing reinforced concrete, monolithic walls, and in the spans between the walls on monolithic reinforced concrete columns.

1.2. The standard technological map is intended for use in the development of Work Production Projects (WPP), Construction Organization Projects (COP), other organizational and technological documentation, as well as for the purpose of familiarizing workers and engineers with the rules for the production of concrete work at the construction site.

1.3. The purpose of creating the presented TTK is to provide a recommended flowchart for the technological process of concrete work.

1.4. When linking the Standard Flow Chart to a specific facility and construction conditions, production schemes, volumes of work, labor costs, mechanization equipment, materials, equipment, etc. are specified.

1.5. The installation of a monolithic reinforced concrete floor is carried out on the basis of the Work Project, working drawings and Working Technological Maps, which regulate the means of technological support and the rules for performing technological processes during the execution of work.

1.6. The regulatory framework for the development of technological maps is: SNiP, SN, SP, GESN-2001 ENiR, production standards for material consumption, local progressive standards and prices, labor cost standards, material and technical resource consumption standards.

1.7. Working technological maps are reviewed and approved as part of the PPR by the head of the General Contracting Construction and Installation Organization, in agreement with the Customer's organization, the Customer's Technical Supervision and the organizations that will be in charge of the operation of this building.

1.8. The use of TTK helps to increase labor productivity, reduce labor costs, improve the organization and improve the quality of work, reduce costs and reduce construction duration, safe performance of work, organize rhythmic work, rational use of labor resources and machines, as well as reduce the time required for development of project planning and unification of technological solutions .

1.9. The work performed sequentially during the production of concrete work includes:

supply of concrete mixture;

laying concrete mixture.

1.10. Work in progress all year round and are carried out in one shift. The working hours during a shift are:

where is the coefficient of use of the concrete pump by time during the shift (the time associated with preparing the machine for work and carrying out technical maintenance is 15 minutes, breaks associated with the organization and technology of the production process and the driver’s rest are 10 minutes every hour of work).

1.11. Used as a driving mechanism truck-mounted concrete pump SY5420THB-48, on a car chassis ^ VOLVO FM 12, with a capacity of 50 m/hour with a distribution boom 48 m long for supplying concrete mixture horizontally and vertically (see Fig. 1).

Fig.1. Truck-mounted concrete pump SY5420THB-48
The concrete mixture is delivered concrete mixer trucks NTM 1004 on a car chassis ^ VOLVO FM 12, with a mixing drum volume of 8.0 m (see Fig. 2).

Fig.2. Concrete mixer truck NTM 1004
1.12. When concreting the floor slab, a heavy concrete mixture of class B22.5 W6, frost resistance grade F75, meeting the requirements of GOST 7473-94 is used as the main material. The maximum aggregate size is 20 mm, the mobility of the concrete mixture is 8-12 cm along a standard cone.

1.13. Work should be performed in accordance with the requirements of the following regulatory documents:

SNiP 12-01-2004. Organization of construction;

SNiP 3.01.03-84. Geodetic work in construction;

SNiP 12-03-2001. Occupational safety in construction. Part 1. General requirements;

SNiP 12-04-2002. Occupational safety in construction. Part 2. Construction production;

SNiP 3.03.01-87. Load-bearing and enclosing structures;

GOST 7473-94. Concrete mixtures. Technical conditions.

^ 2. TECHNOLOGY AND ORGANIZATION OF WORK

2.1. In accordance with SNiP 12-01-2004 “Construction Organization”, before the start of concrete work at the site, the Subcontractor must, according to the act, accept from the General Contractor the prepared construction site, including the assembled DOKA type floor formwork and the reinforcement frame of the floor installed in the formwork.

2.2. Before starting concrete work, the following activities must be completed:

a person responsible for the quality and safety of work has been appointed;

team members are instructed in safety precautions and familiarized with the working flow chart for the ceiling installation;

the walls of the floor are erected to the level of the bottom of the floor slab;

columns are concreted, the concrete strength is at least 70% of the design;

floor formwork installed;

a volumetric reinforcement frame and embedded parts of the floor were mounted in the formwork;

guides for the vibrating screed are installed;

the routes for the movement of concrete mixer trucks and the working parking lot for the concrete pump are marked;

the necessary installation equipment, equipment, tools and a household trailer for workers’ rest were delivered to the work area;

measures are provided to ensure the preservation of reinforcement outlets from the walls of the floor from corrosion and deformation;

a geodetic alignment of the axes and marking of the position of the ceiling were carried out in accordance with the project.
In addition, you must:

prepare a horizontal platform for a concrete pump;

clean the formwork and reinforcement in the concreting area;

check the strength and tightness of the formwork;

accept the completed reinforcement and formwork work;

prepare reserve places for receiving concrete mixture from concrete mixer trucks;

install a stationary concrete pipeline (if necessary);

install reliable audio communications in the work area;

provide the construction site with alarm systems;

arrange lighting for the work area;

fence openings stairwells and along the perimeter of the building.

2.3. Laying the concrete mixture into the ceiling is carried out using a concrete pump complete with concrete mixer trucks and is carried out along the grips in a certain order. The grips are determined based on the condition of the shifting (daily) operational productivity of the concrete pump, the minimum delivery range of the concrete mixture and whether concreting is carried out only using the boom of the concrete pump or using a concrete pipeline.

2.4. The process of laying concrete mixture consists of work operations associated with feeding it into the formwork and compaction. Before laying the concrete mixture into the formwork, you must check:

formwork fastening elements;

quality of cleaning the formwork from debris and dirt;

quality of cleaning of fittings from rust deposits;

correct installation of the reinforcement cage;

thoroughness of cleaning concrete surface walls from cement film;

lubricating the internal surfaces of the formwork;

placing the design mark for the top of the floor slab concreting (with paint) onto the reinforcement frame.

2.5. Laying the concrete mixture on each grip begins with the strip furthest from the pump and proceeds towards the installation site of the concrete pump. The grips are assigned a width of 1.5-2.0 m and are separated from each other by wooden blocks, which are attached to the floor formwork.

Concrete mixer trucks drive up to the loading hopper of the concrete pump and unload the concrete mixture in portions, which is immediately pumped into the floor slab structure by the concrete pump. Using a flexible hose, the concrete mixture is distributed over the concreting area, starting from the most distant area. The height of free dumping of concrete mixture into the coating should be no more than 1.0 m.

The concrete mixture is laid through one strip in one layer to the full thickness of the floor. Concreting of the strips is carried out using beacon strips (reinforcing bars), which during the period of reinforcement work are installed in rows every 2...2.5 m and attached to the reinforced frame of the floor slab. The floor slab is concreted in a direction parallel to the main or secondary beams. In this case, concrete is fed towards concreting.

Fig.3. Concrete laying scheme
Before laying the concrete mixture, the top surface of the walls and columns must be moistened with water. When concreting the slab, lightweight portable panels are laid on top of the reinforced frame, serving as a work place and preventing deformation of the reinforcement.

During rain, the concreted area must be protected from water entering the concrete mixture. Any accidentally washed away concrete should be removed.

2.6. The concrete mixture is placed in the formwork in compliance with the following conditions:

the upper level of the laid concrete mixture should be 50-70 mm below the top of the formwork panels;

the concrete mixture should have a cone slump of 4-12 cm.

adding water when laying the concrete mixture to increase its mobility is not allowed;

separated from the mixture cold water must be removed;

the optimal mobility of the concrete mixture should be within 8-10 cm;

the water-cement ratio of the concrete shift should be in the range of 0.4-0.6.

2.7. The concrete mixture laid in strips is compacted deep, electric vibrators IV-47B, power N=0.8 kW and is leveled vibrating screed ZM. Along walls and in other places inaccessible to the use of a vibrating screed, the concrete mixture is compacted surface vibrator IV-2, power N=0.6 kW.

2.8. Compaction of the concrete mixture to be laid must be carried out in compliance with the following rules:

the step of rearranging deep vibrators should not exceed one and a half radius of their action, i.e. 50 cm;

the depth of immersion of the deep vibrator into the concrete mixture should ensure its deepening into the previously laid layer by 5-10 cm;

The vibrator should be removed from the concrete mixture with the electric motor turned on without jerking to avoid the formation of voids in the concrete.

2.9. Workers perform vibratory compaction of the concrete mixture while on a wooden ladder.

The deep vibrator is immersed into the compacted layer vertically or with a slight inclination. The tip is immersed quickly, after which it, vibrating, remains motionless for 10-15 seconds, and then is slowly pulled out of the concrete mixture in order to ensure that the vacated space is filled with the mixture.

Fig.4. Compaction of concrete mixture with deep vibrator
Compaction must be stopped when:

no settling of the concrete mixture is observed;

the coarse aggregate is covered with the solution;

laitance appears on the surface;

The release of large air bubbles stops.

The duration of vibration must ensure sufficient compaction of the concrete mixture and ranges from 15 to 30 seconds or is determined empirically. The thickness of the laid layer of concrete mixture should not be more than 1.25 times the length of the working part of the deep-well vibrator. When compacting the concrete mixture, it is not allowed to rest the vibrators on the reinforcement and formwork fastening elements.

The foreman, by visual inspection, determines that the concrete mixture has settled completely in the layer, and only after that gives orders to stop compaction and pour a new layer.

The main signs of the end of settling of mixtures can be:

stopping the release of air from the mixture;

the appearance of cement laitance at the junction of concrete and formwork.

2.10. After internal (deep) vibration of the upper, working layer, they begin its external (surface) compaction. For this purpose they use vibrating screeds ZM, with a width of the compacted strip of 3.0 m. Concrete workers install the vibrating screed on the guides and move it by the halyards, leveling the surface of the concrete mixture. If necessary, remove excess concrete with a shovel or add it to the recesses. After removing the beacon slats, the surface is smoothed with a rubberized tape and a metal trowel.

Fig.5. Leveling the slab surface with a vibrating screed
2.11. Caring for concrete involves keeping it moist during the period of hardening and strength gain by preventing the evaporation of water and its absorption by the formwork. Optimal curing conditions for concrete: temperature +18 °C, humidity 90%.

During the initial period of hardening, concrete should be protected from precipitation or drying, and subsequently the temperature and humidity conditions should be maintained to create conditions that ensure an increase in its strength.

In hot and dry weather, after concreting is completed, during the first days of hardening of the concrete mixture, it is periodically watered with water. Watering begins no later than 10-12 hours, and in hot and windy weather 2-3 hours after finishing concreting.

Watering at temperatures of 15 °C and above is carried out during the first three days during the day at least every three hours, and at least once at night; subsequently, at least three times a day. In dry weather, Portland cement concrete is watered for at least seven days. When the air temperature is below 5 °C, watering is not carried out.

In hot and windy weather, the floor surface is covered with damp matting, sawdust or sand for at least 2 days. Concrete maintenance stops after it reaches 70% of its design strength. The holding period and frequency of watering are determined by the construction laboratory.

2.12. When correcting defects large sizes All loose concrete is beaten off, and the surface of durable concrete is cleaned with a wire brush and washed with water. Then the sinks are sealed with a concrete mixture with small crushed stone or gravel up to 20 mm in size. After cleaning with a brush and rinsing with water, small sinks are rubbed down with cement mortar.

Before resuming laying the concrete mixture, when the concrete reaches a strength of 1.5 MPa, the vertical edge of the set concrete mixture must be cleaned of the cement film, moistened and primed with cement laitance.

2.13. Transportation and supply of concrete mixtures to the construction site is carried out by concrete mixer trucks, ensuring the preservation of the specified properties of the concrete mixture. The concrete mixture is supplied to the laying site using a concrete pump. Calculation of the required number of NTM 1004 concrete mixer trucks capable of loading the SY5420THB-48 concrete pump truck is carried out in the following sequence:

2.13.1. The operational average shift productivity of a concrete pump is calculated using the formula:

where is the technical and certified performance of the concrete pump (50 m3/h);

Coefficient that takes into account the decrease in the productivity of a concrete pump depending on the type of concrete structure (0.5);

A coefficient that takes into account the decrease in concrete pump performance depending on the length of the straight horizontal section of the concrete pipeline at the corresponding pressure in it that occurs when pumping the concrete mixture (0.66);

Coefficient taking into account the loss of time for daily care of the concrete pump and its maintenance (0.93);

Coefficient taking into account the qualifications of a concrete pump operator (0.90);

Coefficient that takes into account the decrease in the productivity of a concrete pump due to various organizational and technological reasons (0.95);

Duration of concreting the structure, hour.

We accept 87 m per shift or 13 m per hour.

2.13.2. Required amount concrete mixer trucks with an average hourly productivity of a concrete pump equal to 13 m/h and the duration of one trip of 1.5 hours (the time of one trip of a concrete mixer truck is taken approximately depending on specific conditions) and will be

we accept 3 concrete mixer truck.

Thus, the set will consist of a SY5420THB-48 truck-mounted concrete pump and three NTM 1004 brand concrete mixers.

TYPICAL TECHNOLOGICAL CARD

ROUTING
FOR INSTALLATION AND DISASSEMBLY OF FORMWORK FOR A MONOLITHIC FLOOR PLATE

1 area of ​​use

1 area of ​​use

1.1. The technological map has been developed to organize the work of workers involved in installing and dismantling the formwork of monolithic reinforced concrete floor slabs.

1.2. The technological map includes the following works:

- installation of formwork;

- dismantling the formwork.

1.3. The work covered by the technological map includes:

- slinging and supplying formwork elements (frame supports, racks, tripods, uniforks, wooden beams, plywood) to the installation horizon;

- arrangement of formwork for the beam;

- installation of formwork for the balcony slab;

- arrangement of formwork under the “tooth”;

- arrangement of formwork for the ceiling;

- arrangement of formwork for the end of the floor slab;

- installation of temporary fencing;

- arrangement of openings;

- dismantling of formwork;

- cleaning, lubrication, storage and transportation of formwork elements.

1.4. The formwork must meet the following requirements:

- strength, immutability, correctness of shape and size;

- reliable perception of vertical and horizontal loads;

- surface density (no cracks), preventing cement laitance from seeping through it;

- ability to provide the required quality of the concrete surface;

- possibility of repeated use;

- manufacturability - ease of use, the ability to quickly install and disassemble.

2. Technology and organization of work

2.1. Requirements for previous work

2.1.1. Before installation of formwork begins, the following work must be completed:

- the base for installing the formwork has been prepared;

- the structures of columns and walls were completed, their acceptance certificates were drawn up based on the as-built geodetic survey;

- elements of the floor formwork were delivered and stored in the installation area of ​​the tower crane;

- presence and marking of formwork elements was checked;

- mechanisms, equipment, devices, tools were prepared and tested;

- lighting of workplaces and construction site was arranged;

- all measures for fencing openings, staircases, and the perimeter of the reinforced concrete slab were completed in accordance with SNiP 12-03-2001 “Labor safety in construction, part 1”;

- the elevation mark has been transferred to the floor.

2.2. Work production technology

Installation of formwork

2.2.1. The installation of floor formwork begins with the delivery of frame supports, telescopic racks, tripods, uniforks, wooden beams, plywood sheets to the installation horizon, to the workplace.

2.2.2. First, formwork is performed at a lower elevation. We begin the work by installing formwork for the beams.

2.2.3. In connection with the chosen method of constructing the formwork, the installation of a double deck, at the same time the formwork is installed under the beam, balcony slab, “tooth”.

2.2.4. Installation of the formwork begins with the installation of ID15 frame supports at a distance of at least 50 mm from the edge of the slab in accordance with the arrangement diagram, l.2 and l.3 of the graphic part.

Pre-set the height of the frame support (distance from the floor to the bottom of the main beam) according to the template by adjusting the screw heads and screw legs.

2.2.5. Install the main beams (2.9 m wooden beam) onto the screw heads (crown).

In accordance with sections 1-1, 2-2, 3-3, 4-4 (l.5, 6 of the graphic part) and the beam layout diagram (l.4 of the graphic part).

2.2.6. Install secondary beams (4.2 m wooden beams) on the main beams at intervals of 400 mm.

In axes G-D/1, E-Zh/7, where the “tooth” passes, if it is impossible to use a 4.2 m beam (the distance between the walls in these places is 2900 mm and 2660 mm), install two paired beams 2 .5 m.

2.2.7. Lay sheets of laminated plywood, 18 mm thick, on the installed secondary beams. Thus, the lower deck is formed (level +6.040). Nail plywood to wooden beams. For the plywood layout diagram, see sheet 4, as well as sheets 5 and 6 of the graphic part.

2.2.8. Level the lower deck.

2.2.9. Using geodetic instruments, place the lines of the edges of the concrete beam on the lower deck to construct a vertical deck.

2.2.10. The vertical deck beam is formed from strips of laminated plywood, 300 mm wide. For dimensions and layout, see sheet 3 of the graphic part.

Connect the plywood strips together with 50x50 timber. The beam is also used so that it is possible to nail it to the lower deck and to the upper one, see node A, sheet 5 of the graphic part.

To stabilize the vertical deck, install a brace from 50x50 timber.

2.2.11. Install 2.5 m wooden beams on the lower deck.

Place an 82x82 beam under these beams (to gain height).

Under the balcony slab, wooden beams are located perpendicular to the concrete beam with a step of 400 mm, under the “tooth” along the concrete beam.

For the layout of wooden beams, see pages 5 and 6 of the graphic part.

2.2.12. Lay sheets of laminated plywood on the installed wooden beams, in accordance with the layout diagram for sheet 3 of the graphic part.

2.2.13. To install the “tooth” where the wall goes, use a bracket.

The bracket is secured with a tie.

A 100x100 beam is placed on the bracket.

Laminated plywood is attached to the beam.

For a diagram of the deck structure, see sections 6-6 and 7-7, sheet 7 of the graphic part.

For a diagram of the placement of brackets for forming a tooth, see sheet 2 of the graphic part.

2.2.14. Installation of formwork under the floor slab.

In accordance with the layout diagram (sheet 2 of the graphic part), measure with a meter and mark with chalk the installation locations of the racks.

Start by installing the outer posts under the main beams, at a distance of 4.0 m along the letter axes.

The distance between the posts along the digital axes corresponds to the pitch of the main beams.

2.2.15. Insert the uni-plug into the rack. Extend the rack according to the template to the length specified by the height to the main (lower) beam. Install the stand and secure it with a tripod.

2.2.16. Install the main beams (4.2 m wooden beams) onto the installed and fastened racks using a mounting fork. The pitch of the main beams is 1.5 m.

2.2.17. Using a mounting fork, install secondary beams (wooden beams 3.3 m) without fastenings onto the main beams. The pitch of the secondary beams is 0.40 m.

2.2.18. Lay sheets of laminated plywood on the secondary beams, close to each other so that the gaps between them are no more than 2 mm. The first sheets of plywood are supplied from the concrete floor; after laying at least 12 sheets, the plywood is supplied to the constructed deck.

The outer perimeter sheets and strips of plywood are nailed to the secondary beams to prevent them from tipping over.

For the plywood layout diagram, see sheet 3 of the graphic part.

2.2.19. Sheets of plywood that fit the formwork under the beam should be laid last, after the vertical deck of the beam has been installed.

2.2.20. For ease of installation of formwork (as well as dismantling), cut a standard sheet of plywood into pieces 2440x610 mm.

2.2.21. In rare places, it is recommended to use ordinary plywood impregnated with emulsion for lubrication.

2.2.22. Places where laminated plywood has been cut become susceptible to moisture and are subject to moisture-resistant treatment (molten paraffin, treatment with two layers of primer).

2.2.23. The deck surface must be leveled.

2.2.24. After installing the deck slab, balcony slab, “tooth”, install a side with a height equal to the thickness of the floor.

The formwork of the end of the floor is performed as follows.

A line is drawn for the end of the slab, strips of plywood are attached to the deck along the line, the width being equal to the height of the ceiling. To prevent the end from tipping over, arrange a strut from 50x50 timber.

2.2.25. Using universal fencing that is attached to wooden beams, create a temporary fence. Install fence posts, with a pitch of no more than 1200 mm, insert fencing boards into the brackets of the posts.

2.2.26. Device of openings. The openings are made of laminated plywood. The size of the openings along the outer edges corresponds to the dimensions of the opening in the floor slab. The openings are installed in the design position and nailed to the floor slab deck.

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TYPICAL TECHNOLOGICAL CARD (TTK)

CONCRECTING OF MONOLITHIC SLOBS AREA OF APPLICATION

A standard flow chart has been developed for concreting monolithic floors

The material was prepared by Demyanov A.A.

1. INSTRUCTIONS FOR CONSTRUCTION TECHNOLOGY OF MONOLITHIC STRUCTURES

General provisions

When constructing monolithic concrete and iron concrete structures it is necessary to be guided by the Building Codes and Rules and the requirements of the work project. The quality of formwork, reinforcement and concrete work is determined by the overall technical level of construction, its reliability and durability. The use of advanced technology and labor organization, complex mechanization means improves the quality of work and reduces the construction time of structures. The decisive influence on the intensity of the construction of monolithic structures is exerted by an integrated approach to ensuring the manufacturability of all stages and equipping production with economical means of comprehensive mechanization of work. Special attention When constructing monolithic structures, intensification of concrete hardening processes is given.

Improving the quality of structures is directly related to compliance with accuracy standards for all monolithic construction operations:

Geodetic and installation work, taking into account known tolerances for the manufacture of elements and parts that determine the equipment at this stage of operation;

Installation of reinforcement and accuracy of fixing the position of working rods;

Layer-by-layer laying and compaction of the mixture;

Modes of heat treatment and curing of concrete.

Improving the quality of monolithic structures is associated with maintaining the accuracy of the technological process of constructing elements and quality control characteristics.

The accuracy of technological processes when performing work is assigned depending on the type of structures and the effect of deviations on the accuracy of the construction of the overlying floors.

The quality of formwork work must be constantly monitored. Instrumental control of formwork systems should be performed at least every 20 revolutions, and for wood elements - every 5 revolutions. When inspecting and accepting the formwork, the following is checked: the rigidity and geometric inapplicability of the entire system and the correct installation of supporting elements; the density of the formwork panels and joints between each other and with previously laid concrete; formwork surfaces and their position relative to the design axes of structures.

During the concreting process, it is necessary to continuously monitor the condition of the formwork, supporting elements and fastenings. The quality of structures is determined by the accuracy and immutability of the position of the reinforcement filling, compliance with the requirements for changing the technological properties of the laid concrete mixture and compaction modes.

An analysis of the actual state of the accuracy of manufacturing structures showed that the statistical dispersion of deviations from the nominal geometric dimensions of structures significantly exceeds the requirements of the standards and indicates a rather low level of technology.

More stringent tolerance requirements should be established for the construction of multi-storey buildings and structures, including monolithic housing construction. Increased demands must be placed on the technology for constructing expansion, settlement, temperature and shrinkage seams. Expansion joints are made with easily deformable materials; rubber bitumen, bitumen-polymer mastics, thiokol sealants, etc.

When concreting structures, technological interruptions are inevitable. In these cases, working seams are arranged. They eliminate movement of the joining surfaces relative to each other and do not reduce the load-bearing capacity of structures. The location of the working seams is assigned in places where the bending moment or shearing force is the smallest. If there is a break in concreting for more than two hours, laying is resumed only after the concrete has reached a strength of at least 1.5 MPa, since if the strength is below 1.5 MPa further installation leads to disruption of the structure of previously laid concrete as a result of the dynamic impact of vibrators and other mechanisms. Before resuming concreting, clean the concrete surface. For better adhesion of previously laid concrete to fresh concrete, working seams on horizontal and inclined surfaces are cleaned of the cement film with a water or air jet, metal brushes or mechanical cutters. Then they cover it with a layer of cement mortar 1.5-3 cm thick to fill all the unevenness.

The concrete mixture is laid in horizontal layers, and it must fit tightly to the formwork, reinforcement and embedded parts of the structure. Layers are laid only after appropriate compaction of the previous one. For uniform compaction, the distance between each vibrator installation must be maintained. The thickness of the concrete layer is set based on the depth of vibration development: no more than 1.25 times the length of the working part of the vibrator when vibrating manually and up to 100 cm when using mounted vibrators and vibrating packages.

When constructing massive structures, stepped concreting is recommended. The duration of laying each layer should not exceed the setting time of the previous layer. In each specific case, the time for laying and overlapping layers is determined by the laboratory, taking into account temperature factors and the characteristics of the mixture.

When compacting the laid layer, the deep vibrator should penetrate 10-15 cm into the previously laid layer and liquefy it. This achieves higher strength of the butt joint between the layers. If, when the vibrator is immersed in a previously laid layer, non-sinking recesses are formed, which indicates the formation of a crystallization structure of concrete, then concreting is stopped and a working seam is made.

For rhythmic work on the construction of monolithic structures, a calculated standard set of formwork is required. For the conditions of work at several sites when concreting different types of structures, the set of formwork is determined depending on the shift production, the ratio of the volumes of the structures being concreted and the modules of their surface.

2. ORGANIZATION AND TECHNOLOGY OF WORK EXECUTION

Basic instructions for concreting floors

1. The technological scheme has been developed for concreting monolithic floors during the construction of a residential building.

2. Concreting of floors is carried out using adjustable formwork on grips, after completion monolithic walls and columns to the bottom level of the floor.

3. Before concreting the floors on each section, it is necessary to:

Provide measures for safe work at heights;

Install formwork;

Install fittings, embedded parts and void formers for wiring;

All structures and their elements that are closed during the concreting process (prepared structural foundations, reinforcement, embedded products, etc.), as well as the correct installation and fastening of the formwork and its supporting elements must be accepted in accordance with SNiP 3.01.01-85.

4. Before concreting, the surface of wood, plywood or metal formwork should be coated with an emulsion lubricant, and the surface of concrete, reinforced concrete and reinforced cement formwork should be moistened. Clean the surface of previously laid concrete from the cement film and moisten it or cover it with cement mortar.

5. Protective layer The reinforcement is maintained using inventory plastic clamps installed in a checkerboard pattern.

6. To align the top level of the concrete floor, spatial clamps are installed or removable beacon strips are used, the top of which must correspond to the level of the concrete surface.

7. Transportation of the concrete mixture to the site is carried out by concrete trucks with unloading of concrete into bunkers (Fig. 1) at the concrete receiving site. The concrete mixture is supplied to the floor structure in hoppers with a volume of 1.0 cubic meters. using a tower crane.

Fig.1. Receiving concrete from a dump truck

8. When concreting, walking on the reinforced floor is allowed only on panels with supports resting directly on the floor formwork.

9. When unloading the concrete mixture from the bunker into the floor formwork, the distance between the lower edge of the bunker and the surface on which the concrete is laid should be no more than 1.0 m (Fig. 2).

Fig.2. Unloading concrete mixture from the bunker into the floor formwork

10. The concrete mixture should be laid horizontally in layers 1.5 - 2 m wide of equal thickness without breaks, with a consistent laying direction in one direction in all layers.

11. Laying the next layer of concrete mixture is allowed before the concrete of the previous layer begins to set. The duration of the break between laying adjacent layers of concrete mixture without forming a working joint is established by the construction laboratory.

12. When concreting flat slabs, working joints, in agreement with the design organization, are placed anywhere along the axis of the wall. The surface of the working seam (Fig. 3) must be perpendicular to the surface of the slab, for which purpose slats along the thickness of the slab are placed in the intended places where concreting is interrupted.

Fig.3. Construction of the working seam

13. Resumption of concreting at the site of construction of the working seam is allowed when the concrete reaches a strength of at least 1.5 MPa and the cement film is removed from the surface of the seam with a mechanical brush, followed by watering.

14. To compact the concrete mixture, deep vibrators (IV-66, IV-47A) or surface vibrators (PV-1, PV-2) are used.

The concrete mixture is laid in the structure in layers of 15...30 cm with careful compaction of each layer. The most common method of compacting concrete is vibration. At the construction site, internal (deep), external and surface vibrators are used (Table 1). Vibrators are activated electric shock(electric vibrators) or compressed air (pneumatic vibrators). In massive structures, concrete is placed using internal vibrators. Surface vibrators are used to compact concrete mixtures in floor slabs, floors and other similar structures. External vibrators are used for concreting densely reinforced thin-walled structures. The duration of vibration at each vibrator installation location depends on the plasticity (mobility) of the concrete mixture and is 30...60 s. A sign of sufficient vibration is the cessation of concrete slumping and the appearance of laitance on its surface. Excessive vibration of the concrete mixture is harmful as it can lead to delamination of the concrete. The step of rearranging the internal vibrators is from 1 to 1.5 of their radius of action.

Table 1 Vibrators

When there is a large supply of concrete to large masses, batch (group) vibrators are used. Large structures are concreted in sections (blocks) with working (construction) joints. The block dimensions in plan are no more than 50...60 sq. m. and height up to 4 m.

It is possible to resume interrupted concreting after the setting process in the previously laid concrete mixture has completed and the concrete acquires a strength of at least 1.2 MPa, approximately 24-36 hours after laying the concrete. To ensure reliable adhesion of concrete in the working joint, the surface of the previously laid concrete is carefully processed: by notching, the top film of the mortar is removed and the coarse aggregate is exposed, blown with compressed air and washed with a stream of water, wiping with wire brushes, and in the places where the reinforcement is released, the rods are cleaned of the mortar.

15. During operation, it is not allowed to rest the vibrator on reinforcement and embedded parts of a monolithic structure. Do not perform vibration compaction in places where electrical boxes are directly installed.

16. The step of rearranging deep vibrators should not exceed one and a half radius of its action; surface vibrators are rearranged so that the vibrator platform in the new position overlaps the adjacent vibrated area by 50-100 mm (Fig. 4).

Fig.4. Diagram of rearrangement of deep vibrators

17. The duration of vibration at each position should ensure sufficient compaction of the concrete mixture, the main signs of which are the cessation of its settling, the appearance of laitance on the surface and the cessation of the release of air bubbles.

18. In places where reinforcement, embedded products or formwork prevent proper compaction of the concrete mixture by vibrators, it should be additionally compacted by jointing.

19. During the concreting process and upon completion, it is necessary to take measures to prevent adhesion of formwork elements and temporary fastenings to the concrete.

Concrete maintenance should ensure that the proper curing temperature is maintained and that freshly placed concrete is protected from quick drying. Freshly laid concrete, first of all, is protected from exposure to rain and sunlight (covering with matting, tarpaulins, bags, sawdust) and systematically watered in dry weather for 7 days for concrete on Portland cement or aluminous cement and 14 days on other cements (one-time watering 0.5...1.0 kg/sq.m.). When the air temperature is below 5 °C, watering is not carried out. The movement of people along concreted structures and the installation of scaffolding and formwork on them for the construction of overlying structures is allowed only after the concrete reaches a strength of at least 1.2 MPa.

The adhesion of concrete to formwork increases over time, so the formwork must be removed as soon as the concrete acquires the required strength. Stripping the side surfaces of concrete structures is allowed after the concrete has achieved strength, ensuring the safety of their corners and edges, which is observed when the concrete strength is at least 2.5 kg/sd sq., achieved in 1...6 days depending on the grade of concrete and the quality of cement and temperature conditions of concrete hardening.

Removal of load-bearing formwork of reinforced concrete structures is allowed when the concrete reaches its design strength, %:

slabs and vaults with a span of up to 2 m...................................50

beams and purlins with a span of up to 8 m....................................70

slabs and vaults with a span of 2...8 m...................................70

load-bearing structures with a span of more than 8 m............100

In all cases, loading structures with the full design load is allowed after the concrete has acquired its design strength.

The demoulding of structures must be carried out in a certain sequence. In multi-storey buildings, formwork is carried out floor by floor, and within a floor, individual structures are removed in different terms. When dismantling the formwork posts of the underlying floor (1st floor), everything is left behind if the overlying floor (2nd floor) is being concreted above it. Safety posts should be located at a distance of no more than 3 m from the supports and from each other. The demoulding of structures should be carried out without impacts or jolts. To avoid damaging the formwork panels when tearing them off the concrete, use different types crowbars. It is not allowed to tear off panels from concrete using cranes and winches.

After removing the formwork, small cavities on the surface of the concrete can be cleaned out with wire brushes, washed with a stream of water under pressure and rubbed with a greasy cement mortar of 1:2 composition.

Large sinks and cavities are cleared to their full depth, removing weak concrete and protruding pieces of aggregate, then the surface is treated with wire brushes and washed with a stream of water under pressure, sealed with a rigid concrete mixture and thoroughly compacted.

20. Quality control of the concrete mixture and concrete is carried out by the construction laboratory in accordance with GOST 10180-90. Weight quality control data is recorded in the concrete work log. Particular attention should be paid to monitoring the vibration compaction of the concrete mixture.

21. When carrying out work, it is necessary to be guided by the requirements of SNiP 3.03.01-87 "Load-bearing and enclosing structures", SNiP 12-03-2001, SNiP 12-04-2002 "Occupational safety in construction" and SP 12-135-2003 "Occupational safety in construction. Industry standard instructions on labor protection."

Concreting with a concrete pump

Currently widely used concrete pumps, which are a concrete pump with a full-rotating distribution boom mounted on a frame, which, in turn, is mounted on a vehicle chassis (Fig. 5).

Fig.5. Supplying concrete mixture with a concrete pump:

A- general form;

b- diagram of possible positions of the concrete pump boom (numbers in meters indicate the delivery range);

1 - flexible sleeve; 2 - articulated boom; 3 - concrete pipeline; 4 - hydraulic cylinder; 5 - concrete pump; 6 - pump receiving hopper; 7- concrete mixer truck

Truck-mounted concrete pumps are designed to supply concrete mixture to the laying site both vertically and horizontally. Along the boom, consisting of three articulated parts, runs a concrete pipeline with hinges - inserts at the joints of the boom, ending with a flexible distribution hose (Fig. 6) on supports (Fig. 7).

Fig.6. Concrete mix supply

Normal operation of concrete pumps is ensured if a concrete mixture with a mobility of 5... 15 cm is pumped through a concrete pipeline, meeting the requirements of ease of pumping, i.e. the ability to transport it through a pipeline over extreme distances without delamination and the formation of plugs. The optimal mobility of the concrete mixture in terms of its ease of pumpability is 6...8 cm, and the water-cement ratio is 0.4...0.6.

Fig.7. Type of supports for concrete pipeline:

a - inventory telescopic stand; b - inventory trestles made of reinforcing steel

It is recommended to use gravel or non-needle-shaped crushed stone as a coarse aggregate. The largest grain size of coarse aggregate should not exceed 0.4 of the internal diameter of the concrete pipeline for gravel and 0.33 for crushed stone. The number of grains of the largest size and grains of lamellar (horse) or needle-shaped form should not exceed 15% by weight.

Before transporting the concrete mixture, the pipeline is lubricated by pumping lime paste or cement mortar. After concreting is completed, the concrete pipe is washed with water under pressure and an elastic wad is passed through it. During a break of more than 30 minutes, the mixture is activated by periodically turning on the concrete pump to avoid the formation of traffic jams; during breaks of more than 1 hour, the concrete pipeline is completely emptied of the mixture (Fig. 8).

Fig.8. Scheme of organizing a workplace when concreting a monolithic slab

NOTE.

1. When concreting monolithic floors, table or frame formwork "DOKA" is used.

2. The layout of formwork panels on floors, the order of concreting by grips, formwork fastening points, places for attaching struts, as well as additional requirements for concreting using formwork of this type are indicated in the project developed by the owner of the formwork.

3. Dismantling of the floor formwork is permitted after the concrete has reached at least 70% of its design strength.

4. When carrying out monolithic work in areas that do not have reliable fences, workers must be secured with a safety belt with an extension cord to avoid falling from a height. The fixing points are indicated by the master or foreman.

3. REQUIREMENTS FOR THE QUALITY OF WORK PERFORMANCE

Quality control

The quality of concrete and reinforced concrete structures is determined both by the quality of the material elements used and by the careful compliance with the regulatory provisions of the technology at all stages of the complex process.

This requires control and is carried out at the following stages: upon acceptance and storage of all source materials (cement, sand, crushed stone, gravel, reinforcing steel, timber, etc.); in the manufacture and installation of reinforcing elements and structures; in the manufacture and installation of formwork elements;

when preparing the base and formwork for laying the concrete mixture; when preparing and transporting concrete mixture; when caring for concrete during its hardening.

All source materials must meet the requirements of GOSTs. Indicators of material properties are determined in accordance with a unified methodology recommended for construction laboratories.

In the process of reinforcing structures, control is carried out upon acceptance of steel (presence of factory grades and tags, quality of reinforcing steel); during warehousing and transportation (correct storage by brands, grades, sizes, safety during transportation); in the manufacture of reinforcing elements and structures (correct shape and size, welding quality, adherence to welding technology). After installing and connecting all the reinforcing elements in the concreting block, a final check is carried out for the correctness of the dimensions and position of the reinforcement, taking into account permissible deviations.

During the formwork process, the correct installation of formwork, fastenings, as well as the density of joints in panels and joints, the relative position of formwork forms and reinforcement (to obtain a given thickness of the protective layer) are monitored. The correct position of the formwork in space is checked by reference to the alignment axes and leveling, and the dimensions are checked by ordinary measurements. Permissible deviations in the position and dimensions of the formwork are given in SNiP (Part 3) and reference books.

Before laying the concrete mixture, check the cleanliness of the working surface of the formwork and the quality of its lubrication.

At the stage of preparing the concrete mixture, the accuracy of dosing of materials, the duration of mixing, the mobility and density of the mixture are checked. The mobility of the concrete mixture is assessed at least twice per shift. The mobility should not deviate from the specified value by more than ±1 cm, and the density should not deviate by more than 3%.

When transporting the concrete mixture, care must be taken to ensure that it does not begin to set, does not disintegrate into its components, or lose mobility due to loss of water, cement or setting.

At the installation site, you should pay attention to the height of dropping the mixture, the duration of vibration and the uniformity of compaction, avoiding the stratification of the mixture and the formation of cavities and voids.

The process of vibration compaction is monitored visually, by the degree of settlement of the mixture, the cessation of air bubbles escaping from it and the appearance of laitance. In some cases, radioisotope density meters are used, the operating principle of which is based on measuring the absorption of radiation by a concrete mixture. Density meters are used to determine the degree of compaction of the mixture during vibration.

When concreting large masses, the uniformity of concrete compaction is controlled using electrical converters(sensors) resistance in the form of cylindrical probes located along the thickness of the layer being laid. The principle of operation of the sensors is based on the property of concrete, with increasing density, to reduce resistance to the passage of current. Place them in the vibrator coverage area. At the moment the concrete reaches a given density, the concrete operator receives a light or sound signal.

The final assessment of the quality of concrete can be obtained only on the basis of testing its compressive strength to failure of sample cubes made from concrete simultaneously with its placement and maintained under the same conditions in which the concrete of the concrete blocks hardens. For compression testing, samples are prepared in the form of cubes with an edge length of 160 mm. Other sizes of cubes are also allowed, but with the introduction of a correction for the result obtained when crushing samples on a press.

For each class of concrete, a series of three twin samples is made.

To obtain a more realistic picture of the strength characteristics of concrete, cores are drilled from the body of structures, which are subsequently tested for strength.

Along with standard laboratory methods for assessing the strength of concrete in samples, indirect non-destructive methods for assessing strength directly in structures are used. Such methods, widely used in construction, are mechanical, based on the use of the relationship between the compressive strength of concrete and its surface hardness, and ultrasonic pulse, based on measuring the speed of propagation of longitudinal ultrasonic waves and the degree of their attenuation.

At mechanical method concrete strength control using Kashkarov's standard hammer . To determine the compressive strength of concrete, a Kashkarov hammer is placed with a ball on the concrete and a blow is applied to the body of the standard hammer with a mechanic's hammer. At the same time, the ball bottom is pressed into the concrete, and the top one into the reference steel rod, leaving imprints on both the concrete and the rod. After measuring the diameters of these indentations, their ratios are found and the compressive strength of the surface layers of concrete is determined using calibration curves.

With the ultrasonic pulse method, special ultrasonic devices such as UP-4 or UKB-1 are used, with the help of which the speed of passage of ultrasound through the concrete of the structure is determined. Using the calibration curves of the ultrasonic speed and the compressive strength of concrete, the compressive strength of concrete in a structure is determined. Under certain conditions (constancy of technology, identity of source materials, etc.), this method provides quite acceptable control accuracy.

IN winter conditions In addition to the general requirements stated above, additional control is carried out.

During the preparation of the concrete mixture, the following is monitored at least every 2 hours: the absence of ice, snow and frozen lumps in unheated aggregates supplied to the concrete mixer when preparing a concrete mixture with antifreeze additives; temperature of water and aggregates before loading into the concrete mixer; concentration of salt solution; temperature of the mixture at the outlet of the concrete mixer.

When transporting concrete mixtures, once a shift the implementation of measures for covering, insulating and heating the transport and receiving containers is checked.

During preliminary electrical heating of the mixture, the temperature of the mixture in each heated portion is controlled.

Before laying the concrete mixture, check the absence of snow and ice on the surface of the base, abutting elements, reinforcement and formwork, ensure that the thermal insulation of the formwork meets the requirements of the technological map, and, if it is necessary to warm up the abutting surfaces and the foundation, ensure that this work is carried out.

When laying the mixture, its temperature is monitored during unloading from vehicles and the temperature of the laid concrete mixture. Check the compliance of waterproofing and thermal insulation of unformed surfaces with the requirements of technological maps.

During the curing process of concrete, the temperature is measured at the following times: when using the “thermos” method, preliminary electrical heating of the concrete mixture, heating in hothouses - every 2 hours on the first day, at least twice per shift in the next three days and once a day for the rest holding time; in the case of using concrete with anti-frost additives - three times a day until it acquires the specified strength; when electrically heating concrete during a period of temperature rise at a rate of up to 10 °C/h - every 2 hours, in the future - at least twice a shift.

After curing the concrete and stripping the structure, the air temperature is measured at least once per shift.

The temperature of concrete is measured by remote methods using temperature wells, resistance thermometers, or technical thermometers are used.

The concrete temperature is controlled in areas subject to the greatest cooling (in corners, protruding elements) or heating (at electrodes, at contacts with thermoactive formwork at a depth of 5 cm, as well as in a number of massive concreting blocks). The measurement results are recorded in the temperature control sheet.

When electrically heating concrete, the voltage and current on the downstream side of the supply transformer are monitored at least twice a shift and the measured values ​​are recorded in a special journal.

The strength of concrete is controlled in accordance with the requirements set out above and by testing an additional number of samples made at the place where the concrete mixture is laid in the following periods: when kept using the “thermos” method and with preliminary electrical heating of the concrete mixture - three samples after the concrete temperature has been reduced to the calculated final one, and for concrete with antifreeze additives - three samples after the concrete temperature has been reduced to the temperature for which the amount of additives is calculated; three samples after the concrete structures have reached a positive temperature and the samples have been kept in normal conditions for 28 days; three samples before loading structures with standard load. Before testing, samples stored in the cold are kept for 2...4 hours to thaw at a temperature of 15...20 °C.

When using electric heating, heating in thermoactive formwork, infrared and induction heating of concrete, maintaining cube samples in conditions similar to the heated structures is, as a rule, not feasible. In this case, the strength of concrete is controlled by ensuring that the actual temperature conditions correspond to the specified ones.

With all methods of winter technology, it is necessary to check the strength of concrete in the structure non-destructive methods or by testing drilled cores if control samples cannot be maintained under structural curing conditions.

For all operations to control the quality of technological processes and the quality of materials, inspection (test) reports are drawn up, which are presented to the commission accepting the facility. During the course of work, they draw up acts of acceptance of the base, acceptance of the block before laying the concrete mixture and fill out temperature control work logs in the prescribed form.

OPERATIONAL QUALITY CONTROL SCHEME

Composition of operations and controls

Technical requirements for the construction of monolithic sections in floors

Technical requirements for the installation of monolithic coatings

The maximum size of crushed stone and gravel for concrete pavements should not exceed 15 mm and 0.6 of the pavement thickness (h).

Compressive strength of marble chips for coatings:

Mosaic not less than 600 MPa;

Polyvinyl acetate-cement concrete and latex-cement concrete not less than 800 MPa.

When checking the adhesion of monolithic coatings to underlying floor elements by tapping, there should be no change in the nature of the sound. monolithic floor vibrator concreting

Not allowed:

Gaps and cracks between baseboards and floor coverings or walls (partitions);

Potholes, cracks, waves on the surface of coatings;

Cutting monolithic coatings into separate cards, with the exception of multi-color coatings (with the installation of dividing veins).

4. MATERIAL AND TECHNICAL RESOURCES

The set of standard formwork kits should be made taking into account: technical means of delivering mixtures of intra-building transport; delivery means; laying and compaction; methods of heat treatment and care of concrete. The organization of concrete work should provide for the full provision of complex teams with standard kits, including equipment, power tools, inventory and fixtures. In table 1 shows the approximate equipment of the brigade with individual means. In addition, it is necessary to have a standard kit for the welder and fitter.

Standard set of an integrated team for conducting concrete work

Table 1

5. ENVIRONMENTAL AND SAFETY RULES

Occupational health and safety instructions for concrete workers

I. General requirements

1. The concrete worker is obliged to work in the special clothing and safety shoes issued to him and keep them in good condition. In addition, he must have the necessary safety devices for work and use them at all times.

2. Before starting work, workplaces and passages to them must be cleared of foreign objects, debris and dirt, and in winter - from snow and ice and sprinkled with sand.

3. It is prohibited to work in an area where there are no fences around open wells, pits, hatches, holes in ceilings and openings in piles. At night, in addition to fencing in dangerous places, light signals must be installed.

4. If there is insufficient illumination of the workplace, the worker is obliged to inform the foreman about this.

5. The concrete worker is prohibited from screwing in and out electrical lamps that are under voltage and moving temporary electrical wiring. This work must be performed by an electrician.

6. It is prohibited to be in the operating area of ​​lifting mechanisms, or to stand under a raised load.

7. The concrete worker is not allowed to turn on and off mechanisms and signals that he has nothing to do with.

8. Machines, power tools and lighting lamps can only be turned on using switch starters, etc. No worker is allowed to connect or disconnect live wires. If it is necessary to extend the wires, call an electrician.

9. To avoid electric shock, do not touch poorly insulated electrical wires or unprotected parts electrical devices, cables, tires, switches, lamp sockets, etc.

10. Before starting up the equipment, you should check the reliability of the guards on all open rotating and moving parts.

11. If a malfunction is detected in the mechanisms and tools with which the concrete worker works, as well as their fences, the work must be stopped and the foreman must be immediately informed.

12. Upon receipt of the tool, you must make sure that it is in good working order: a faulty tool must be returned for repair.

13. When working with hand tools (scrapers, bush hammers, shovels, tampers), it is necessary to ensure that the handles are in good condition, that the tool is tightly fitted on them, and that the working surfaces of the tool are not knocked down, blunted, etc.

14. It is prohibited to operate power tools from ladders.

15. An electrified tool, as well as the electrical wire supplying it, must have reliable insulation. Upon receipt of the power tool, you should check the condition of the wire insulation by external inspection. When working with the tool, make sure that the power cord is not damaged.

16. At the end of the work, the powered tool must be disconnected from the power supply and placed in the storeroom.

17. When carrying aggregate materials and concrete mixture, workers must know that the maximum permissible load is:

for women 20 kg

for female teenagers 10 kg

for male teenagers 16 kg

Teenagers under 16 years of age are not allowed to carry heavy loads.

18. When moving construction cargo in wheelbarrows its weight should not exceed 160 kg.

19. To avoid colds, all open openings in the premises must be sealed with temporary shields.

20. In the cold season, you should use rooms specially designated for heating. Heating in boiler rooms, wells of heating mains, in bunkers, as well as on air heaters is prohibited.

21. In the event of an accident involving a workmate, you should provide him with first aid, and also inform the foreman or foreman.

II. Transporting concrete mixture

22. When feeding concrete mixture with a belt conveyor, its upper end should be positioned above the load receiving area for a length of at least 0.5 m.

23. During operation of the conveyor belt, it is necessary to monitor its stability, as well as the good condition of the protective canopies enclosing the conveyor over the passages and driveways.

24. When the conveyor belt is sliding, throwing sand, clay, slag and other materials between the belt and the drum is not allowed. To do this, you need to stop the conveyor and call an on-duty mechanic.

25. Clean the rollers and conveyor belt from adhering concrete, as well as tension and strengthen the latter only when the electric motor is turned off. In this case, it is necessary to post a warning sign on the starter: “DO NOT TURN ON!”, and remove the fuses. Only an electrician can remove fuses.

26. You should cross conveyor belts on special bridges with railings.

27. When lifting concrete mixture with cranes, it is necessary to check the reliability of fastening of the tub or container to the crane hook, the serviceability of the container and the sector valve. The distance from the bottom of the tub or container at the time of unloading to the surface on which unloading occurs should not be more than 1 m.

28. When delivering concrete in a dump truck, the following rules must be observed:

a) at the moment the dump truck approaches, all workers must be on the side of the road opposite the one on which the movement is taking place;

b) it is not allowed to approach the dump truck until it has come to a complete stop, stand at the stacker bunker and be under a raised load while unloading the dump truck;

c) the raised body should be cleaned of adhering pieces of concrete with a shovel or a scraper with a long handle; the bottom of the body should not be hit from below; Cleaning workers must stand on the ground. Standing on the wheels and sides of the dump truck is prohibited;

d) you cannot walk along the roadway of overpasses on which dump trucks move.

III. Laying concrete mixture

29. Before starting to lay the concrete mixture into the formwork, you must check:

a) fastening of formwork, supporting scaffolding and working decks;

b) fastening to the supports of loading funnels, trays and trunks for lowering the concrete mixture into the structure, as well as the reliability of fastening individual links of metal trunks to each other;

c) the condition of the protective canopies or flooring around the loading funnels.

30. Before laying the concrete mixture into forms, the correctness and reliability of the mounting loops must be checked

31. Concrete should be laid in structures located 1.5 m below the level of its supply only using trays, link trunks and vibrating trunks.

32. When laying concrete mixture from unfenced areas at a height of more than 3 m, as well as when concreting structures with a slope of more than 30 degrees. (cornices, lanterns, coverings) concrete workers and workers serving them must work using safety belts attached to reliable supports.

33. Concreting joints of prefabricated elements at a height of up to 5.5 m should be done from ordinary scaffolding, and at higher heights - from special scaffolding

34. Dispensing of concrete mixture into one or another vibrating robot must be carried out at the direction of the work manager or foreman using a predetermined alarm

35. When feeding concrete mixture through vibrating robots, it is necessary that:

a) links of vibrating robots were attached to the safety rope;

b) the vibrators were securely connected to the trunk;

c) winches and steel ropes for pulling the trunk were securely fastened;

d) the lower end of the trunk has been secured, and the strength of the fastening should be systematically checked;

e) while unloading the concrete mixture, no one should be under the vibrating robot.

IV. Compaction of concrete mixture with vibrators

36. Concrete workers working with vibrators are required to undergo a medical examination, which must be repeated every 6 months.

37. Women are not allowed to work with a manual vibrator.

38. Concrete workers working with electrified tools must know the measures to protect against electric shock and be able to provide first aid to the victim.

39. Before starting work, you must carefully check the serviceability of the vibrator and make sure that:

a) the hose is well attached and if it is accidentally pulled, the ends of the winding will not break;

b) the supply cable has no breaks or bare spots;

c) the grounding contact is not damaged;

d) the switch operates properly;

e) the bolts ensuring the tightness of the casing are well tightened;

f) the connections of the vibrator parts are sufficiently sealed and the electric motor winding is well protected from moisture;

g) the shock absorber on the vibrator handle is in good condition and adjusted so that the vibration amplitude of the handle does not exceed the norms for a hand tool.

40. Before starting work, the body of the electric vibrator must be grounded.

The general serviceability of the electric vibrator is checked by testing it in a suspended state for 1 minute, but it is impossible to

41. To power electric vibrators (from the distribution panel), four-core hose wires or wires enclosed in a rubber tube should be used; the fourth wire is necessary for grounding the vibrator housing operating at a voltage of 127 or 220 V.

42. The electric vibrator can only be turned on using a switch protected by a casing or placed in a box. If the box is metal, it must be grounded.

43. Hose wires must be suspended and not laid over laid concrete.

44. It is prohibited to drag the vibrator by the hose wire or cable when moving it.

45. If live wires break, contacts spark, or the electric vibrator malfunctions, you should stop working and immediately notify the foreman or workman about this

46. ​​Working with vibrators on ladders, as well as on unstable scaffolding, decking, formwork, etc. prohibited.

47. When working with electric vibrators, you must wear rubber dielectric gloves or boots

48. To prevent the vibrator from falling, it should be secured to the structure support with a steel rope.

49. It is prohibited to press a portable vibrator with your hands to the surface of the concrete being compacted; Moving the vibrator manually during operation is only permitted using flexible rods.

50. When working with a vibrator with a flexible shaft, it is necessary to ensure the direct direction of the shaft, in as a last resort with small smooth bends. The formation of loops on the shaft is not allowed to avoid an accident.

51. During prolonged operation, the vibrator must be turned off for five minutes every half hour to cool down.

52. During rain, vibrators should be covered with a tarpaulin or removed indoors.

53. During breaks in work, as well as when concrete workers move from one place to another, the vibrators must be turned off.

54. When watering concrete or formwork, a concrete worker working with a vibrator should not allow water to come into contact with it.

55. When operating a vibration platform, careful supervision must be provided over the condition of the limit switches and the device for lifting the vibration shield. Particular attention must be paid to the reliable operation of the traverse bolt lock in the upper position.

56. To reduce noise during operation of a vibrating unit, it is necessary to attach forms to vibrating machines and systematically check the tightness of all fastenings

57. It is not allowed to go down into the pit of the vibrating platform during its operation.

58. Standing on the form or on the concrete mixture when compacting it, as well as on the vibrating platform, vibrating inserts or on the frame of the molding machine when they are working is prohibited

59. At the end of the work, vibrators and hose wires should be cleaned of concrete mixture and dirt, wiped dry and put in the storeroom, and the wires should be folded into coils. The vibrator can only be cleaned after disconnecting it from the mains. It is prohibited to wash vibrators with water.

V. Concrete work in winter conditions

60. Before working with chemical accelerators for concrete hardening, the concrete worker must undergo special instructions on safe handling with chemicals, as well as a medical examination. It should be remembered that calcium chloride, used as an accelerator for the setting and hardening of concrete, is dangerous for the skin of the face and hands, and bleach and its aqueous solutions are strong oxidizing agents that can release chlorine gas.

Persons under 18 years of age are not allowed to work on the preparation of chlorinated solutions.

61. Chlorinated water should be prepared in a separate room located at a distance of no closer than 500 m from residential buildings.

62. When working with calcium chloride or when using bleach and chlorinated mixtures, you must wear a respirator or gas mask and rubber gloves.

63. Calcium chloride can be used as an accelerator only in diluted form. When diluting a solution of calcium chloride, use scoops with long handles.

64. Workers concreting structures exposed to electrical heating must undergo special training on safe working methods. Those working near heated areas should be warned about the danger of electric shock.

65. Heated areas of concrete should be fenced off and well lit at night. Fences are installed at a distance of at least 3 m from the border of the area under current.

At the boundaries of the site, warning posters and inscriptions should be posted: “DANGER!”, “CURRENT ON”, as well as rules for providing first aid in case of electric shock.

66. Work on electrical heating of concrete should be carried out under the supervision of experienced electricians. It is prohibited for people to stay in electrical heating areas and perform any work, with the exception of measuring temperature. Only qualified personnel should take temperature measurements. Moreover, this must be done using protective equipment.

67. Electrical heating of reinforced concrete structures should be carried out at a voltage not exceeding 110 V.

68. In the area of ​​electrical heating work there must be a warning light, located in a visible place and lighting up when the current is turned on in the area. From this point on, only persons servicing the installation may be on the work site.

69. Workers performing electrical heating are required to work in dielectric rubber shoes and the same gloves; the tool must have insulated handles.

70. Before concreting, you should make sure that the heated area is not under current.

71. When concreting in poorly lit areas, it is allowed to use portable lamps with a voltage of no more than 12 V.

72. Before unloading the concrete mixture, the concrete worker is obliged to make sure that the reinforcement and electrodes are located correctly. The distances between the electrodes and the reinforcement must be at least 5 cm. The concrete mixture must be unloaded very carefully, without moving the electrodes.

73. Watering concrete is allowed only after the stress in the heated structures has been relieved.

74. Before electrical heating of concrete, for better contact with the wires, the protruding ends of the electrodes must be cleaned of the concrete mixture. After electrical heating is completed, the ends of the electrodes protruding from the concrete must be cut off.

75. It is not permitted to work on a site where concrete is electrically heated. The work should be carried out with a special installation tool using dielectric gloves and galoshes. Tools must have insulated handles.

76. Measure the temperature of concrete in dielectric rubber galoshes and gloves. In this case, it is necessary to exercise extreme caution, not to come close to the structure, and also not to lean on it. Work should be performed, if possible, with one hand, holding the other behind your back or to the side.

77. In structures heated using thermal formwork, the outer surfaces of the formwork and sawdust moistened with water acquire increased current conductivity, therefore, during electrical heating, when the current is turned on, touching the thermal formwork and sawdust is prohibited.

78. It is prohibited to touch water pipes, taps, dispensers and other open parts of water lines that are energized during electrical heating, as well as the stream of water flowing from them.

79. It is prohibited to check the presence of voltage on parts of the electrical installation by hand. For this purpose, current detectors or test lamps with lugs at the ends of the wires should be used.

80. Walking or transporting energized concrete in the electrical heating zone is permitted only along specially constructed passages and scaffolds.

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Design and calculation of formwork, basic requirements for it. Preparation and installation of fittings. Methods for ensuring the design protective layer of concrete. Designing the composition of a concrete mixture for concreting a structure. Quality control of reinforced concrete works.

This technical map provides for the following procedure for carrying out work:

Formwork work:

Transportation of formwork to the installation area;

Marking the base for the pitch of the main posts;

Installation of main stands with tripods and uniforks;

Installation of connections along racks;

Installation of longitudinal beams;

Installation of cross beams;

Treatment of plywood ends with anti-adhesive lubricant;

Installing and securing the plywood deck;

Installation of intermediate racks in the spans between the main ones;

Installation of formwork for the side surfaces of the floor slab;

Treating the deck with anti-adhesive lubricant.

The pitch of the main and secondary racks, main beams, secondary beams is determined according to table. 1. and fig. 1

Rice. 1. Scheme of arrangement of main and secondary racks, main beams, secondary beams

Reinforcement works:

Transportation to the laying area of ​​reinforcement products, fasteners, embedded parts, opening formers, thermal liners, PVC pipes;

Construction of a alignment base from guide reinforcing bars of the lower mesh;

Construction of a lower mesh of individual reinforcing bars with viscous joints with wire;

Installation of spacers - protective layer clamps;

Installation of reinforcement rods for the lower mesh, near the holes in the slab and the places where the greatest forces occur;

Installing a cutoff to form a working seam

Laying heating wires with fastening to the bottom mesh using tie wire;

Installation of supporting frames and securing them to the lower mesh using binding wire;

Cleaning the surface of the formwork from snow and ice;

Construction of a alignment base from guide reinforcing bars of the upper mesh;

Construction of an upper mesh of individual reinforcing bars with viscous joints with wire;

Installation of embedded parts, openings, thermal inserts, channels for electrical wiring;

Installation of reinforcement rods for the upper mesh, near the holes in the slab and the places where the greatest forces occur;

Construction of a technological seam by securing a chain-link mesh between the upper and lower reinforcement bars;

Installation of limiter boards for forming the upper and lower protective layers at the upper and lower surfaces of the technological seam.

Covering the reinforced floor (to prevent snow from getting into the structure).

Concrete works:

Receiving concrete mixture into the bunker;

Supply of concrete mixture to the concreting area;

Laying concrete mixture with compaction using an in-depth vibrator;

Leveling the concrete mixture according to the beacon marks;

Smoothing the concrete mixture;

Cleaning the receiving hopper, tools, and equipment from concrete.

Curing:

Covering open, unformed surfaces of the slab with P/E film.

Connecting heating wires to power cables, supplying voltage from a transformer.

Temperature measurements in concrete.

Stripping:

Disconnecting the transformer, dismantling the power cables;

Removing the canopies, cleaning them, rolling them up and storing them on pallets for further transportation to a new location;

Dismantling and storing intermediate racks;

Lowering the deck on the main posts;

Turning the cross beams “on their side”;

Dismantling and storing plywood panels;

Dismantling and storing cross beams;

Dismantling and storing longitudinal beams;

Dismantling and storing main stands and tripods;

Transportation of formwork elements;

Cleaning formwork elements from concrete;

Installation of re-supporting racks.

Performers

The work is carried out in a sequential manner by a complex team of 6 people, taking into account the combination of the following professions:

Carpenter-concrete worker 4 categories – 2 people (P1, P2);

Carpenter-concrete worker 3rd category – 2 people; (P3, P4);

Carpenter-concrete worker 2nd category – 2 people; (P5, P6)

At the same time, all workers must have skills in laying reinforcement products and tying reinforcement joints. In addition, at least two people from the flight must be certified slingers.

If workers do not have the above-mentioned specialties and qualifications, they must be trained and certified before starting work.

Preparatory work

Before starting work you must:

Complete the construction of external and internal load-bearing walls, while the strength of the latter at the time of dismantling the floor formwork should ensure the absorption of loads from it;

The premises in which work on the construction of monolithic floors will be carried out must be cleared of fixtures, equipment, and unused building materials;

Clear the base on which the floor formwork posts will be installed from debris, ice, and snow (in winter); in addition, it must be designed for loads transmitted from the posts.

Formwork work

Work on the installation of formwork begins with the installation of the main racks. To do this, the base is broken down according to the pitch of the main racks. A 20 m tape measure and chalk are used as a tool and equipment; it is possible to use a template strip of a certain length corresponding to the pitch of the main posts. The breakdown of the base is carried out by two workers P1 and P5. At this time, P2 and P3 carry out transportation of formwork elements in containers by vertical transport using a crane, or horizontal transport using a hydraulic trolley - a “Rokhlya” type loader and supplying the elements to the installation site. At the same time, P4, P6 carry out the enlarged assembly and installation of the supporting elements of the formwork: a unifork is inserted into the rack, and the rack is secured in a tripod at the installation site. The height of the mounted racks is adjusted so that after installation the deck is 20-30 mm higher than the design position.

Rice. Integrated stand assembly:

1 – stand, 2 – unifork, 3 – spring clamp

Rice. Installation of a stand with a tripod: 1 – stand with a unifork; 2 - tripod

Rice. Installation in a corner or against a wall

Rice. General view of the room after installation of the main racks

After installing the main posts and adjusting their height, the longitudinal beams are installed and vertical connections are installed. Installation of longitudinal beams is carried out using a mounting rod directly from the base.

Rice. Mounting rod

Rice. Installation of longitudinal beams: 1-main stand with tripod and unifork; 2-mounting rod; 3-mounted longitudinal beam

After installing the first longitudinal beam in a row, the next one is joined to the already mounted one, secured in a unifork. To ensure the stability of the formwork and its absorption of horizontal loads with a formwork height of more than 3.0 m, it is necessary to arrange vertical connections using fastening brackets and edged boards with a cross-section (hb) of 25100 mm. The following labor organization is proposed: workers P2 and P3 carry out transportation of formwork elements in containers by vertical transport using a crane, or horizontal transport using a hydraulic trolley - a “Rokhlya” type loader and preliminary laying out the beams at the place of their installation; link of workers P1 and P5, perform installation of longitudinal beams; link of workers P2, P6 performs the installation of vertical connections.

Rice. Vertical connections: 1-post; 2-longitudinal beam; 3-fastening bracket; 4-board

Rice. Mounting bracket

The installation of the transverse beams is carried out in sections of two workers using mounting rods directly from the base. The following scheme for organizing the work of workers is proposed: workers P2 and P3 carry out transportation of formwork elements in containers by vertical transport using a crane, or horizontal transport using a hydraulic trolley - a “Rokhlya” type loader and preliminary laying out the beams at the place of their installation; worker links P1, P5 and P2, P6 carry out the installation of transverse beams in adjacent spans.

Before starting work on the installation of plywood sheets, the cross beams are aligned using a template, then the plywood is laid on the cross beams and secured in the corners of the plywood sheets with nails. Installation of the first sheets of plywood is carried out from the installation sites. Next, an inventory ladder is used to move people onto the deck.

The first sheets of plywood in the span are laid and secured from the stepladder, the remaining sheets are from previously laid ones. Only the outer sheets of plywood are fastened with nails (screws).

The following organization of labor is proposed: worker units P1, P5 and P2, P6 align the transverse beams and lay sheets of plywood, as well as fastening them with nails (screws). Workers P3 and P4 deliver plywood sheets to the laying site, treat the ends of the plywood sheets with form lubricant using a spray gun, and level the formwork with the participation of a foreman (foreman). Worker P3 places the lath at the bottom of the main beams, the foreman (foreman) takes a reading from the level, calculates the marks (height of the main and secondary beams + height of the plywood sheet) and gives a command about the required change in deck height, worker P4, using the support nut of the rack, adjusts the height of the deck . After this, the foreman (foreman) takes a second reading on the rail; if the deck is in the design position, or the deviation does not exceed the standard values, then the section of the deck under the next rack is leveled, otherwise worker P4, using the support nut, re-adjusts the deck in height. The formwork is aligned until the deck reaches its design position or its deviations do not exceed standard values.

Rice. Fastening plywood: 1-cross beams; 2-fixed sheet of plywood; 3-nail; 4-sheet of plywood secured with nails

At the next stage, cutters are installed - elements for molding the end surface of the floor slab. When installing cut-offs, the brackets are first secured with nails, then a deck made of plywood or boards is attached to the brackets.

The following organization of workers' labor is proposed: worker unit P1, P5 marks the outer edge of the slab and installs brackets; workers P2, P6 install and secure the cutter deck from plywood sheets or boards, workers P3 and P4 process the plywood sheets with form lubricant using a spray gun.

After installing the cut-offs, the fencing is installed around the perimeter of the floor being constructed: inventory racks of the fence are installed on the cut-off brackets, onto which the board fencing sides are installed.

Rice. Floor formwork fencing

On final stage Formwork work involves installing intermediate posts. To do this, insert a gripping head with a locking latch (or a unifork) into the intermediate posts and install the posts with the required pitch.

Rice. Capture head. 1 – fixing latch

Rice. Installation of intermediate racks: 1-main rack; 2 - longitudinal beam; 3-intermediate stand; 4-head-gripper

The following organization of workers' labor is proposed: worker unit P3, P4 delivers and assembles the racks: they insert gripper heads into the racks; worker units P1, P5 and P2, P6 use a tape measure or template to mark the base for the intermediate racks and install these racks.

Installation of formwork for reinforced concrete beams at the edge of the ceiling:

Rice. Scheme of formwork arrangement for reinforced concrete beams at the edge of the floor

A, B – floor formwork; C – fencing of the floor formwork.

Reinforcement works

1. Before starting work, you must:

Complete the installation of the floor formwork; the formwork must be rigidly secured and its spatial stability ensured;

When performing work in winter period clear the deck surface of snow and ice;

Install inventory ladders for climbing onto the floor formwork, check the presence and reliability of fencing along the contour of the floor formwork and at height differences of more than 1.3 m.

2. Work on reinforcing the floor slab begins with delivery to the reinforcement zone necessary materials and devices for the centering base of the lower mesh. To deliver reinforcement products to the laying area, lifting mechanisms (cranes) are used; if there is no stationary crane at the construction site, truck-mounted cranes are used. In order to ensure that the loads on the formwork from reinforcement products do not exceed permissible values, the reinforcement is supplied to the floor formwork in small packs (no more than 2 tons), the distance between the packs must be at least 1 m. During the work, the link of workers P3, P4 carries out slinging of the reinforcement products and feeding them to the laying area. Worker units P1, P5 and P2, P6 receive and unfasten the reinforcement on the floor formwork. Next, a alignment base is constructed from the reinforcing bars of the lower mesh. To do this, a link of workers P1, P6 breaks down the floor formwork for laying reinforcement using a tape measure and chalk (marker) according to the drawings for the slab reinforcement. At this time, the worker links P2, P6 and P3, P4 carry out the laying of reinforcing bars of the lower mesh in one of the directions. After that, workers P1, P6 align the reinforcing bars, but the pitch of the grooves and their depth correspond to the pitch of the mesh bars and the diameter of the reinforcement. After the rods are aligned, they are secured using reinforcing bars laid in a perpendicular direction through an enlarged step. Each intersection of reinforcing bars when constructing the alignment base is fixed using a binding wire.

Rice. Layout of the deck when installing the lower reinforcing mesh: 1 – load-bearing wall; 2 - inventory fence; 3 – floor formwork deck; 4 - roulette; 5 - centering axes placed on deck

Rice. The procedure for fastening reinforcing bars with binding wire: a) movement diagram of the working binding intersection of the bars; b) scheme for fastening the reinforcing mesh rods: 1-transverse rods; 2 – longitudinal rods; 3 – the beginning of the worker’s path; 4 – end of the worker’s path; 5-path of movement of the worker; 6 – intersection of reinforcing bars, secured with tying wire.

Knitting of reinforcing bars is carried out using pre-prepared pieces of knitting wire and a knitting hook. To perform this operation, a knitting wire in the form of a loop is passed under the intersection of the reinforcing bars, and the free ends of the wire are twisted by a rotational movement of the knitting hook until the bars are rigidly fixed in the knot. After finishing the laying of the bars, the workers P3, P4 construct a protective layer, installing reinforcement clamps under the reinforcing bars of the connected lower mesh. The spacing of the clamps for the protective layer of the reinforcement is assigned based on the rigidity of the mesh, ensuring the design position, and is assigned depending on the diameter of the reinforcement:

- Ø8 – 0.5m;

- Ø10 – 0.6m;

- Ø12 – 0.8m;

- Ø14 – 0.8m;

- Ø16 – 1.0m

Rice. Scheme for fixing reinforcing bars with tying wire: a) pulling the wire under the knot; b) alignment of the ends of the wire; c) twisting the ends of the wire with a crochet hook; d) fixed node: 1 – reinforcing bar;

Rice. Installation of reinforcement clamps: 1-longitudinal rod; 2 – transverse rod; 3 – knitting wire; 4 – clamp; 5 - deck

In winter, the heating wires PNSV 1,2 are laid out and secured. To avoid damage to the wires, they are secured to the reinforcement of the lower mesh only with soft wire or twists from pieces of PNSV 1.2 wire. The ends of the wires are brought out and secured in the place where the main different-phase wires will pass. The length of the wire loop and the laying pitch are assigned depending on climatic conditions, the corresponding recommendations are given in the section “Work in winter conditions”.

Rice. Heating wire laying diagram

At the next stage of the reinforcement work, the installation and fastening of the supporting frames and reinforcement frames with the help of knitting wire to the lower reinforcing mesh is carried out. In this case, the following work organization scheme is assumed: workers P3 and P4 lay out and prepare the frames for installation (they give the supporting frames a zigzag bend, which ensures their stability); workers P1, P5 and P2, P6 secure the frames to the lower mesh using knitting wire.

Rice. Installation of supporting frames: 1 - reinforcing mesh rods; 2 - supporting frame; 3 - securing the supporting frame to the reinforcing mesh with knitting wire; 4 - working installation frame; 5 - working fastening frame.

After installing the supporting frames, the transverse rods of the upper mesh are laid. To perform this operation, the worker links P2, P6 and P3, P4 carry out the laying of the reinforcing bars of the upper mesh in the transverse direction. After which workers P1, P6 align the reinforcing bars using a template. After the rods are aligned, they are secured using reinforcing bars laid in the longitudinal direction through an enlarged step. Each intersection of reinforcing bars when constructing the alignment base is fixed using a binding wire. Next, the reinforcing bars of the upper mesh are laid in the longitudinal direction (filling the enlarged spans between the longitudinal bars laid with enlarged steps.

Rice. Arrangement of the upper reinforcing mesh: 1-supporting frames; 2-transverse reinforcing bars of the upper mesh, laid with the design spacing; 3-longitudinal reinforcing bars laid with an increased span; 4-fastening the upper transverse rods to the supporting frames using tying wire. Note: the bottom grid is not shown

To carry out this process, the worker link P3, P4 carries out the laying of bars in the longitudinal direction, filling the enlarged longitudinal spans between the alignment rods, the worker links P1, P5 and P2, P6 carry out the alignment of the reinforcing bars of the upper mesh in the longitudinal direction and fastening the nodes of the upper mesh using knitting wire . When securing the nodes of the upper reinforcing mesh with knitting wire, workers move in the same way as when securing the nodes of the lower reinforcing mesh.

Next, the installation and fastening of openings, embedded parts and thermal liners, and the construction of a technological seam are carried out. To construct a technological seam, along with its passage, a reinforcement cage is installed between the upper and lower reinforcing mesh. A chain-link mesh with a small mesh (no more than 1010 mm) is attached to the frame using a knitting wire. Under the lower reinforcing mesh, along the line of the technological seam, a board is laid and secured, the thickness of which is equal to the thickness of the protective layer of the lower reinforcement. The board is secured to the upper reinforcement in the same way; its thickness should be no less than the thickness of the protective layer of the upper reinforcement. At the final stage, anti-adhesive grease is applied to the formwork panels. It is recommended to use as an anti-adhesive lubricant: betrol, emulsol, adenol. Apply anti-adhesive grease to the surface of the formwork panels using a spray gun or by painting with a brush or roller.

Rice. 1 - top board for forming a protective layer; 2 - upper reinforcing mesh; 3 - chain-link mesh fixed to the reinforcement frame; 4 - lower reinforcing mesh; 5 - bottom board for forming a protective layer; 6 - deck (plywood); 7 - cross beam; 8 - longitudinal beam; 9 - reinforcement clamp.

Laying and compacting concrete

1. Before starting concrete work, it is necessary to:

Complete the installation of reinforcement; the reinforcement must be rigidly fixed to ensure its design position during the concreting process;

Inspect the installation of formwork and floor reinforcement with the execution of the corresponding act.

Concrete mixture is supplied to the laying area:

Concrete pump with characteristics for of this object(concrete distribution boom);

According to the “tap-tub” system.

2. It is proposed to use a “tap-bucket” system to supply concrete mixture to the laying area. The concrete mixture is received into the rotary hopper directly from the concrete mixer vehicle. The concrete mixture in the bunker is transported by a tower crane to the placement site, where it is placed into the floor formwork and compacted using deep vibrators. The vibrator displacement step is taken to be 300 mm. The signal that compaction is complete is that, under the influence of vibration, sedimentation of the concrete mixture has stopped, and air bubbles have ceased to be released from it.

Next, the surface of the concrete structure is smoothed using smoothers. After this, open unformed surfaces are covered with P/E film; in winter, insulated tarpaulin canopies (efa, sawdust) are additionally laid on top of the P/E film and temperature wells are installed in the body of the concrete using a PVC pipe plugged in the lower part.

Rice. Construction of a temperature well: 1 – concrete floor slab; 2 - PVC tube; 3 - heat-conducting liquid; 4 – plug.

During the work, workers P3, P4 monitor the unloading of the concrete mixture into the bunkers, slinging and supplying the concrete mixture to the place where it is placed in the structure. Worker P1 places the concrete mixture into the structure, controlling the movement of the hopper as the volume of the floor slab structure is filled. Worker P5 compacts the concrete mixture using an internal vibrator. Workers P2, P6 level the concrete mixture with shovels and smooth its surface using trowels, after which they also cover the smoothed surfaces with polyethylene film, and in winter, insulate the polyethylene film with insulated canopies and install temperature wells.

Rice. Concrete laying: 1 – bunker for supplying concrete; 2 – concrete to be laid; 3 – reinforcing mesh; 4 – design of the floor formwork; 5 – inventory fence.

When laying a concrete mixture with a concrete pump, the concrete mixture is received into the receiving hopper of the concrete pump directly from the concrete mixer vehicle. The concrete mixture is supplied in portions by a concrete mixing boom to the placement site, where, using a flexible tip, it is placed into the floor formwork and compacted using deep vibrators. The vibrator displacement step is taken to be 300 mm. The signal that compaction is complete is that, under the influence of vibration, sedimentation of the concrete mixture has stopped, and air bubbles have ceased to be released from it.

Next, the surface of the concrete structure is smoothed using smoothers. During work, the driver of the concrete pumping installation and worker P6 inspect and regulate the concrete mixing plant, supply the concrete mixture to the place of its distribution in the structure, monitor the operation of the installation and eliminate traffic jams in the receiving bin. Workers P1, P5 carry out the laying of concrete mixture into the structure, controlling the flexible boom tip of the concrete pump as the volume of the floor slab structure is filled. Worker P2 compacts the concrete mixture using an internal vibrator.

Rice. Laying concrete: 1 – arrowhead of a concrete pump; 2 – concrete to be laid; 3 reinforcement mesh; 4 - design of the floor formwork; 5 - inventory fence.

Curing

When performing work at subzero temperatures:

Unformed surfaces of structures should be covered with steam and heat insulating materials immediately after concreting is completed (PE film + tarpaulin canopies (stage, sawdust)).

Reinforcement outlets of concrete structures must be covered or insulated to a height (length) of at least 0.5 m.

Curing concrete at winter concreting monolithic structures should be produced using the “heating wire” method.

The strength of concrete should be monitored, as a rule, by testing samples made at the site where the concrete mixture is laid. Samples stored in the cold must be kept for 2-4 hours at a temperature of 15-20 C before testing.

It is allowed to control the strength by the temperature of the concrete during its curing.

Movement of people on concreted structures and installation of formwork on overlying structures is allowed after the concrete reaches a strength of at least 1.5 MPa.