Technical map for concrete work. TTC

CENTRAL INSTITUTE FOR REGULATORY STUDIES AND SCIENTIFIC AND TECHNICAL INFORMATION "ORGTRANSSTROY"
MINISTRIES OF TRANSPORT CONSTRUCTION

PREPARATION OF CEMENT CONCRETE MIXTURE IN THE C-780 INSTALLATION

1 AREA OF USE

The technological map was developed on the basis of the application of methods of scientific organization of labor and is intended for use in the development of a project for the production of work and organization of labor at mixing plants for the preparation of cement concrete mixtures.

The automated cement concrete plant (CBZ) with the S-780 plant is designed for the preparation of rigid and plastic concrete mixtures with aggregates up to 40 mm.

The capacity of the plant is up to 30 m 3 /h. The capacities of the supply bins for cement, aggregates, water tank are designed for half an hour of operation at maximum productivity and the highest water-cement ratio = 0.5.

The plant consists of mixing and dosing departments, aggregate warehouse and cement warehouse.

The consumable warehouse of aggregates is open, located directly near the S-780 concrete mixing plant. Screening and washing of the material is also organized here. Sand and crushed stone are delivered in railway cars, unloaded by a multi-bucket gantry unloader S-492 directly over the funnels of the vibrating chutes of the gallery conveyor.

The automated warehouse of cement S-753 is intended for short-term storage of cement. The silo tower with a capacity of 25 g is equipped with two cement level indicators of the UKM type. Cement from railroad cars is unloaded directly into the cement warehouse using a pneumatic unloader S-577.

The dosing unit of the plant consists of feed hoppers with continuous pendulum batchers S-633. The dispensers are installed above the horizontal conveyor, which supplies materials to the inclined conveyor. On the inclined conveyor they fall into the loading tray of the mixing department.

The cement supply hopper is a cylinder with a conical part at the bottom. Cement is fed directly into the S-781 dispenser with a drum feeder. Inside the bunker, two C-609A cement level indicators are installed, included in the warehouse control scheme. Turning on or off the mechanism that supplies cement from the warehouse is done using the same indicators.

The S-780 continuous forced mixing plant is the main equipment of the concrete plant. The working body of the mixer is two shafts of square section 80 × 80 mm with blades mounted on them. The blades end with blades measuring 100×100 mm. The body of the agitator ends with a storage hopper with a jaw gate.

Concrete mixing plant S-780 is connected with warehouses: cement aggregates and dosing unit by a system of belt and bucket feeders.

In all cases of using the technological map, it is necessary to link it to local conditions, depending on the composition, brand and quantity of the produced mixture.

Depending on the replacement needs of cement concrete mix the plant can be adjusted to any productivity within the range from 15 to 30 m 3 /h by changing the productivity of its batchers: cement from 5 to 10 t/h, sand and crushed stone from 12.5 to 25 g/h and water up to 6 m 3 .

So, for example, at a specified by the laboratory of the plant, the consumption of materials per 1 m 3 of concrete (cement - 340 kg, sand - 547 kg, crushed stone fraction 5-20 mm - 560 kg, crushed stone fraction 20-40 mm - 840 kg, water - 170 kg ) the productivity of the plant will be:

Day dispenser	Productivity of batchers, t/h at plant productivity m 3 /h
Day dispenser


Crushed stone fraction 15-20 mm
Crushed stone fraction 20-40 mm

2. INSTRUCTIONS ON THE TECHNOLOGY OF THE PRODUCTION PROCESS

Prior to the start of the work of the cement concrete plant with the S-780 installation, all equipment is inspected and, if necessary, the batchers of aggregates, cement and water are calibrated.

Calibration of dispensers is carried out with a change in the productivity of the plant, the brand and composition of the concrete mixture, the volumetric weight and particle size distribution of aggregates.

With a certain plant productivity and, accordingly, the composition and brand of the mixture, it is also necessary to periodically calibrate the dispensers.

Aggregate dispenser calibration

Aggregate dispensers are calibrated by sampling. For this you need:

a) fill the supply bins with sand, small and large gravel in an amount of at least 5 m 3 of each material;

b) set the batchers by level to a horizontal position (with material) by moving the load lever or changing the load in the ballast box (near the variator).

In this case, the movable dampers should be set to a height of 100 mm for crushed stone, and 80 mm for sand. The fixed dampers are installed 10 mm higher than the movable dampers. Checking the absence of jamming or jamming in the weighing system of the dispensers is carried out by lightly pressing on the edge of the weighing platform or by placing a weight of 0.5 kg. In this case, the platform should be lowered to the stop;

c) prepare for calibration commodity scales with a load capacity of at least 0.5 T, a box with a capacity of 200 m and a stopwatch.

For sampling, it is necessary to turn on the horizontal collection conveyor to move in reverse side by switching the direction of the motor (reversing). When testing one dispenser, the rest must be turned off.

The horizontal collecting conveyor shall be switched on during the test period.

At the command of a laboratory assistant holding a stopwatch, the operator turns on the dispenser. Sand or crushed stone is poured onto a metal sheet for 4-5 seconds until a stable flow of poured material is obtained. After that, the stopwatch is turned on and the box is placed under the flow of the dosed material.

After the sampling time has elapsed, at the signal of the laboratory assistant, the collection conveyor and the dispenser are turned off. The sample taken is weighed on a scale.

Three weighings are made for one position of the variator.

The hourly productivity of the dispenser is determined by the arithmetic mean of the weight of three samples according to the formula:

where α - arithmetic mean value of the weight of three samples in kg without tare;

t- sampling time in sec. If the weight of the samples does not exceed ± 2% of the calculated value, it is considered that at the given position of the variator pointer the dispenser works stably.

Similarly, the calibration of other batchers of aggregates is performed.

To calibrate the cement dispenser, you must:

a) unscrew the bolts fastening the branch pipe of the cement hopper and turn the branch pipe by 90 °;

b) make sure that the cement supply hopper is completely filled with cement. Check the level of cement in the supply hopper using the level indicators on the control panel of the mixing plant;

c) prepare for tare commercial scales with a carrying capacity of at least 0.5 T, two boxes with a capacity of 200 l, a stopwatch, a shovel, a branch pipe made of tin with a diameter of 130-150 mm, a length of 3-3.5 m.

Sampling is carried out for each of all five positions of the variator arrow.

To do this, a box is installed under the nozzle, at the command of the laboratory assistant, the driver turns on the cement dispenser. Cement from the dispenser enters the pipe, and from it into the box until a stable, cement supply mode and normal speed of the electric motor are set by eye. The time required to obtain a stable flow of material is typically 50-60 seconds. After this time, the stopwatch is simultaneously turned on and the pipe is transferred to the loading of the box. The box is loaded within 90 seconds for 1, 2, 3 positions of the variator arrow, and within 60 seconds - for 4, 5 positions of the arrow. After the specified time has elapsed, the sample taken is weighed on the balance. Three samplings are made for each position of the variator needle. Cement dosing accuracy ± 2% of the calculated weight.

To control the correct calibration, the operation of the dispenser is checked at the selected capacity and with continuous operation of the dispenser for 10 minutes by taking three samples in a box, especially paying attention to the operation of all mechanisms and the uninterrupted flow of material into the dispenser.

To calibrate the water dispenser, you must:

a) turn the drain pipe through which water enters the mixer by 180 ° on the flange and lengthen it with an additional pipe up to 4 m long;

b) turn off all equipment not related to water dosing.

The metering device is calibrated by sampling, for which it is necessary to turn on the metering pump when the drain pipe. At the same time, water from the tank through the dosing pump and the three-way valve returns back to the tank through the ring. At the command of a laboratory assistant holding a stopwatch, the operator switches the three-way valve to the position of supplying water to the mixer, and water is supplied to the barrel until a stable continuous flow of water is established. After that, the stopwatch is simultaneously turned on and the three-way valve is instantly switched to supply water to the water meter tank. The container is filled within 60 seconds for positions 1, 2 and 3 of the variator arrow, and within 30 seconds for positions 4 and 5 of the arrow. After the specified time has elapsed, at the command of the laboratory assistant, the three-way valve is switched to drain and the stopwatch is turned off. The operator switches the three-way valve to the position for supplying water through the ring. The sample taken is measured.

To maintain the main quality indicator of the concrete mixture (water-cement ratio), it is necessary to calibrate the water dispenser with an accuracy of ± 1%.

After calibrating all batchers, the installation builds a graph of the productivity of a concrete plant, depending on the position of the arrow of the variator of each batcher (Fig. 1).

Rice. 1. Graph of the dependence of the productivity of the dispensers on the positions of the arrow of the variators:

1 - water; 2 - crushed stone fraction 5-20 mm; 3 - crushed stone fraction 20-40 mm; 4 - sand; 5 - cement

This graph is valid when the plant is running on permanent materials that make up the concrete mix.

To change the productivity of the dispensers, it is necessary to change the gear ratio by the variator. To do this, set the arrows of the variator (only on the move) to the appropriate division along the approximate curve and, by subsequent calibration, make the necessary correction to their position.

The correct operation of the dispensers is checked daily at the beginning of the shift by a representative of the CBZ laboratory. The weighing device is installed in accordance with the composition of the concrete mixture approved by the chief engineer of the construction department and taking into account the moisture content of the aggregates. Access to weighing cabinets and dosing devices, as well as changes in the amount of materials, is allowed only for laboratory employees.

The components of the concrete mixture immediately after entering the concrete plant are subject to control by the laboratory of the Central Biomedical Plant and the Central Laboratory of Construction Management. The quality of materials is checked by external inspection and by sampling.

The plant operates according to the scheme given in Fig. 2.

Rice. 2. Technological scheme of the cement concrete plant with the S-780 plant for the preparation of concrete mix:

1 - vibration feeders; 2 - conveyors; 3 - aggregate bunkers; 4-dispensers of aggregates; 5 - cement dispenser; 6 - cement bunker; 7 - belt conveyor; 8 - mixer; 9 - drive for concrete; 10 - water tank; 11 - water dispenser; 12 - three-way valve; 13 - receiving hopper; 14 - silo bank; 15 - filters

The bulldozer alternately pushes the aggregates onto the 1 vibrating trays, from where the 2 conveyors feed them into the 3 feed bins.

When the bunkers are fully loaded, the upper level indicator is activated and the vibrating tray and conveyors are turned off after the material remaining on the belt has passed, and the light signal for the end of loading is turned on. When the material is depleted in the supply hopper to the lower level indicator, the conveyor, vibrating tray, light and sound signals for the start of loading are switched on.

Cement from the silo can 15 is fed into the feed bin 6 by a pneumatic injection system. From the supply hopper, the cement enters the weighing pendulum batcher 5. The indicators of the upper and lower levels of cement have light and sound signals to the cement warehouse control panel.

Water in the tank 10 of the mixing compartment is pumped from a special tank.

Crushed stone of fraction 5-20, 20-40 mm and sand are continuously dosed by belt pendulum dispensers 4, to which the material comes from supply bins.

First, crushed stone of a fraction of 20-40 mm is dosed onto the tape, then crushed stone of a fraction of 5-20 mm and sand, and on top of these materials - cement. This feed order eliminates the build-up of small particles of material on the belt.

Dosed materials are fed through the feed funnel into the mixer. Water from the tank is dosed by means of a dosing pump and fed through the pipeline directly into the working mixer.

Sulfite-alcohol stillage is prepared in a special installation and introduced into the water in an amount of 0.2-0.3% of the weight of cement per 1 m 3 of concrete (0.68-1.0 kg / m 3).

In the mixer, the concrete components are intensively mixed and transported by paddle shafts to the outlet. From the mixer, the finished mixture enters the hoarder, and is unloaded through the jaw gate into a dump truck.

The quality of the cement concrete mixture obtained in the C-780 mixing plant primarily depends on the continuity of its operation, since at each stop the calculated ratio of the components of the concrete mixture, especially cement and water, changes.

Quality control of the cement concrete mixture is carried out by the factory laboratory 2-3 times per shift.

With the same composition and correct dosing, the mobility, workability, bulk density and yield of concrete must be constant.

The output of concrete is determined at least once a month with a change in the composition of the concrete.

The amount of concrete released from the factory and placed in the case should be checked daily.

When performing work, the following safety rules must be observed:

Persons familiar with the design of this equipment and safety regulations are allowed to operate the equipment of concrete plants;

Before starting the equipment, it is necessary to check the reliability of the guards on all open, rotating and moving ones; parts;

It is necessary to ensure the good condition of not only the automation system, but also local start-up mechanisms. In the event of a malfunction of the local start-up, the operation of the automated plant is not allowed;

It is allowed to turn on machines, tools and lighting lamps only with the help of starters or knife switches;

Repairs to electrical equipment and wiring may only be carried out by an electrician;

Repair of pipelines of pneumatic systems under pressure is prohibited;

At the end of the operation of the mixing plant, it is necessary to turn off the general switch, and close the box in which it is located;

In the absence of transport for more than 1.5 hours, it is necessary to clean the blades and the trough from the concrete mix and rinse the mixer with water, as well as clean the jaw gate of the storage hopper;

To prevent foreign objects from entering the hopper, a grate must be installed above the loading opening. When preparing a mixture with chemical additives, the worker must use rubber gloves and safety glasses.

3. INSTRUCTIONS FOR THE ORGANIZATION OF WORK

Works on the preparation of cement-concrete mixture are carried out in two shifts.

The mixing plant is serviced by a team consisting of 8 people, including cement concrete mix preparers, machinists: 5 razr.-1; 4 bits-1; batcher of cement-concrete mix components 3 size-1; electrical fitter 5 category-1; locksmith construction 4 razr.-1; bulldozer driver 5 years - 1; transport (auxiliary workers) 2 razr.-2.

Before starting work, the cement concrete mix preparers and the batcher must check the completeness of the equipment of the installation, the absence of foreign objects near the rotating parts or on the conveyor belts.

Mixing plant operator 5 years manages the operation of the concrete mixing plant as a whole: monitors the approach, loading and dispatch of vehicles, gives an audible signal to drivers for loading, in the absence of vehicles, turns off the plant and ensures that after the plant is turned off, there is no concrete mixture left in the mixer.

Mixing plant operator 4th grade. checks the presence of water in the tank and the dosing tank, cement in the feed hopper, inspects the agitator, checks the empty operation of the jaw lock and the agitator without materials, checks the operation of the variator, turns on the water pump that supplies water to the water dosing tank of a constant level, turns on the mixer, then the aggregate supply conveyor opens the water shut-off valve, turns on the cement dispenser and controls the preparation of the cement concrete mix. Monitors the operation of the installation mechanisms, ensures the smooth operation of all units and performs routine repairs.

The batcher of components of cement concrete mix 3 razr. checks the presence of aggregates in the supply bins of the dosing department, the installation height of the fixed and movable shutters, the ease of swinging of the weight conveyor and its horizontal position. It checks the empty operation of the prefabricated and inclined conveyors and, during their normal operation, turns on prefabricated conveyors, vibrating chutes and dispensers in a certain sequence.

Construction locksmith 4 times. checks the presence of cement in the warehouse, the position of the slide gates and the presence of the required amount of cement in the pit or transfer tray. At the direction of the driver of the central console, he checks the idle operation of the pneumopressure system.

Electrician 5th category checks the grounding of electric motors, connects the unit to the mains, together with the drivers checks the operation of electric motors on Idling monitors the precise operation of the automatic control system. During the operation of electric motors, it periodically monitors the mode of their operation, heating and the state of the contacts.

Bulldozer driver 5 years feeds aggregates to the chutes of the underground gallery.

Transport (auxiliary) workers 2 sec. are busy with preparatory and final work: they prepare sulphite-alcohol stillage, remove spilled material from conveyors and dosing units, remove foreign objects from conveyors.

4. SCHEDULE OF THE PRODUCTION PROCESS

Name of works

unit of measurement

Scope of work

The composition of the link (team)

Preparatory work

0,05

5 bits-1

4 " - 1

3 bits-1

electrician
5 bits-1

Construction locksmith
4 bits-1

Bulldozer driver
5 bits-1

2 cut-2

14,27

Shift handover

0,03

Final works

0,05

continuation

Name of works

unit of measurement

Scope of work

Labor intensity for the entire scope of work, man-days

The composition of the link (team)

Production process time

Preparatory work

0,05

Preparers of cement concrete mix, machinists:
5 bits-1

4 " - 1

Dosing unit for cement concrete mix components:
3 bits-1

electrician
5 bits-1

Construction locksmith
4 bits-1

Bulldozer driver
5 bits-1

Transport (auxiliary workers)
2 cut-2

Preparation of cement-concrete mixture (supply of aggregates, cement, water, their dosing, mixing, preparation of additives)

14,27

Shift handover

0,03

Final works

0,05

Notes.

1. The schedule does not provide for nightly preventive maintenance.

2. During the period of start-up and adjustment of the plant, the composition of the team may be changed at the discretion of the chief engineer of the construction department.

5. CALCULATION OF LABOR COSTS FOR THE PREPARATION OF 210 m

Code of rates and prices	The composition of the link	Description of works	unit of measurement	Scope of work	Norm of time, man-hour	Price, rub.-kop.	Standard time for the full scope of work	The cost of labor costs for the full scope of work, rub.-kop.
TNR, § T-1-38, tab. 2a	Preparers of cement concrete mix: 5 bits-1. Component dispenser cement concrete mix: 3 bits-1 electrician 5 bits-1 Construction locksmith 4 bits-1	Preparation of cement-concrete mixture (supply of cement to the supply hopper, dosage of aggregates in cement when supplied to the mixer), water supply to the mixer and introduction (if necessary) of a solution of additives; mixing of materials with the release of the mixture into the storage hopper; release of the finished mixture into dump trucks; preparation of documents for the mixture	100 m 3			12-84		26-96
By the time	Bulldozer driver 5 bits-1 Transport (auxiliary) workers 2 cut-2	Supply of mineral materials (pushing materials to the conveyor gallery with a bulldozer; maintenance of the feeder points of the belt conveyor and the consumable warehouse conveyor and preparation of sulphite-alcohol stillage)	1 shift			13-50		13-50
		Total for 210 m 3

6. MAIN TECHNICAL AND ECONOMIC INDICATORS

The name of indicators	unit of measurement	According to costing	On schedule	How much more or less are the indicators according to the schedule than according to the calculation, %.
The complexity of work per 100 m 3 of the mixture
Average rank of workers
Average daily wage per worker
The utilization rate of the S-780 installation

7. MATERIAL AND TECHNICAL RESOURCES

a) Basic materials

The consumption of materials is determined according to the recipe of the cement concrete mixture. This table shows the average consumption of materials.

Name	Mark, GOST	unit of measurement	Quantity
Name	Mark, GOST	unit of measurement	per unit of production (100 m 3 mixture)	per shift (210 m 3 mix)
Cement grade 500	GOST 10178-62*
Medium sand	GOST 10268-62
Crushed stone fraction 5-20 mm	GOST 8267-64
Crushed stone fraction 20-40 mm	GOST 8267-64

Sulfite-alcohol stillage

b) Machinery, equipment, tools, inventory

Name	unit of measurement		Quantity
Mixing plant with automatic
Continuous dispensers
Automated cement charging
Bulldozer
cement unloader
Belt conveyors		T-144 and RTU-30
Plant for the preparation of SSB additives


Spanners	set

The technological map was developed by the department for the implementation of best practices and technical regulation in the construction of roads and airfields (performed by engineer T.P. Bagirova) based on the materials of the Rostov and Chelyabinsk regulatory research stations of the Orgtransstroy Institute

TYPICAL TECHNOLOGICAL CHART (TTK)

PREPARATION OF CONCRETE MIXTURE ON THE CONSTRUCTION SITE

I. SCOPE

1.1. A typical technological map (hereinafter referred to as TTK) is a comprehensive regulatory document that establishes, according to a specific technology, the organization of work processes for the construction of a structure using the most modern means of mechanization, progressive designs and methods of performing work. They are designed for some average working conditions. The TTC is intended for use in the development of Projects for the production of works (PPR), other organizational and technological documentation, as well as for the purpose of familiarizing (training) workers and engineering and technical workers with the rules for the production of work on the preparation of a concrete mixture at a mixing plant for the preparation of cement concrete mixtures under conditions construction site.

1.2. This map provides instructions for the preparation of concrete mix by rational means of mechanization, data on quality control and acceptance of work, requirements industrial safety and labor protection in the course of work.

1.3. The regulatory framework for the development of technological maps are: SNiP, SN, SP, GESN-2001 ENiR, production norms for the consumption of materials, local progressive norms and prices, norms for labor costs, norms for the consumption of material and technical resources.

1.4. The purpose of creating a TC is to describe solutions for the organization and technology of preparing a concrete mixture in order to ensure its High Quality, as well as:

- cost reduction of works;

- reduction of construction time;

- ensuring the safety of work performed;

- organization of rhythmic work;

- unification of technological solutions.

1.5. On the basis of the TTC, as part of the WEP (as mandatory components of the Work Execution Project), Working Flow Charts (RTC) are developed for the implementation certain types concrete mixing work. Working technological maps are developed on the basis of standard maps for the specific conditions of a given construction organization, taking into account its design materials, natural conditions, the existing fleet of machines and building materials tied to local conditions. Working technological maps regulate the means of technological support and the rules for the implementation of technological processes in the production of work. Technological features, depending on the brand of the prepared mixture, are decided in each case by the Working draft. The composition and level of detail of materials developed in the RTK are established by the relevant contracting construction organization, based on the specifics and scope of work performed. In all cases of application of the TTK, it is necessary to bind it to local conditions, depending on the composition, grade and quantity of the produced concrete mixture.

Working flow charts are reviewed and approved as part of the PPR by the head of the General Construction Contractor, in agreement with the Customer's organization, the Customer's Technical Supervision.

1.6. The technological map is intended for foremen, foremen and foremen who perform work on the preparation of concrete mix, as well as employees of the technical supervision of the Customer and is designed for specific conditions of work in the III temperature zone.

II. GENERAL PROVISIONS

2.1. The technological map has been developed for a set of works on the preparation of concrete mix.

2.2. Works on the preparation of concrete mix are carried out in one shift, the duration of working hours during the shift is:

Where 0.828 is the coefficient of use of mechanisms in time during the shift (the time associated with preparing for work and conducting ETO - 15 minutes, breaks associated with the organization and technology of the production process and the driver's rest - 10 minutes every hour of work).

2.3. The technological map provides for the performance of work by an integrated link with mobile concrete mixing plant BSU-30TZ, overall dimensions of the unit 42500x5850x8400 m, with a capacity of 30 m3/hour equipped with concrete mixer SB-138, bunkers of inert materials m, the capacity of the supply silo of cement - 60 tons, the total power consumption of electricity is 75 kW (see Fig. 1).

Fig.1. Concrete mixing plant BSU-30TZ

2.4. The concrete mixing plant is equipped with automated system control based on an industrial computer, which provides:

- automated control of all technological processes of production;

- multi-recipe technology for the preparation of mixtures (up to 50 recipes);

- accounting for the consumption of materials and the output of concrete by grade;

- accounting for the fulfillment of applications with the preservation of information about the Customer, the time of entering and fulfilling the application, the recipe number and the volume of the mixture;

- output of accounting information to the display and printer.

2.5. Work should be carried out in accordance with the requirements of the following regulatory documents:

- SP 48.13330.2011. Organization of construction;

- SNiP 3.03.01-87. Bearing and enclosing structures;

- GOST 27006-86. Concrete. Rules for the selection of composition;

- GOST 30515-97. cements. General technical conditions;

- GOST 8736-93. Sand for construction work;

- GOST 8267-93. Crushed stone and gravel from dense rocks for construction work;

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

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

III. ORGANIZATION AND TECHNOLOGY OF WORK PERFORMANCE

3.1. The automated concrete mixing plant (BSU) with the SB-138 plant is designed for the preparation of rigid and plastic concrete mixtures with aggregates up to 40 mm. Installation capacity up to 30 m/h; capacities of supply hoppers for cement, aggregates, water tank are designed for half an hour of operation at maximum productivity and the highest water-cement ratio of 0.5. The mobile concrete mixing plant consists of mixing and dosing departments, aggregate warehouse and cement warehouse (see fig. 2). The installation is controlled from the driver's cab, and the electrical equipment is located in a special room. The driver's cab is equipped with instruments that record the course technological process.

Fig.2. Diagram of a concrete mixing plant

1 - consumable bunker fillers; 2 - conveyor-dispenser; 3 - reloading conveyor; 4 - concrete mixer; 5 - concrete mixer frame; 6 - cement dispenser; 7 - dispenser of chemical additives; 8 - water dispenser; 9 - chemical additives unit (at the request of the customer); 10 - consumable cement silo with a filter; 11 - screw conveyor

3.2. Consumable warehouse of sand and fractional crushed stone open type with dividing walls, located directly next to the concrete mixing plant. Sand and fractional crushed stone are delivered to the consumable warehouse in railway cars. In the case of delivery of non-fractional or contaminated crushed stone, sorting of the material into fractions (screening) and washing of the material are also organized here. Sand and crushed stone are fed into the feeders of the batching department and unloaded front loader TO-49 directly over the funnels of the vibrating trays of the gallery conveyor. The SBU dosing unit consists of service hoppers-fillers with pendulum dispensers of continuous action С-633. The dispensers are installed above the horizontal conveyor, which supplies materials to the inclined conveyor. On the inclined conveyor they fall into the loading tray of the mixing department.

3.3. Consumable automated warehouse of cement S-753 with a capacity of 300 tons is designed for short-term storage of cement. Cement from railway wagons is unloaded directly into the cement warehouse using pneumatic unloader С-577 or cement trucks.

The silo tower with a capacity of 60 tons is equipped with two cement level indicators of the UKM type. The cement supply hopper is a cylinder with a conical part at the bottom. Cement is fed directly into dispenser S-781 with drum feeder. Inside the bunker are two cement level indicator С-609А included in the warehouse management scheme. Turning on or off the mechanism that supplies cement from the warehouse is done using the same indicators.

3.4. Concrete mixing plant SB-138 continuous action forced mixing is the main equipment of the concrete batching plant. The working body of the mixer is two shafts of square section 80x80 mm with blades mounted on them. The blades end with blades measuring 100x100 mm. The body of the agitator ends with a storage hopper with a jaw gate.

Concrete mixing plant SB-138 is connected to the warehouses of cement aggregates and the dosing unit by a system of belt and bucket feeders.

3.5. Depending on the changing needs of the cement concrete mix, the plant can be adjusted to any capacity ranging from 15 to 30 m/h by changing the capacity of its batchers: cement from 5 to 10 t/h, sand and crushed stone from 12.5 to 25 t/h and water up to 6 m.

So, for example, at the consumption of materials per 1 m3 of concrete specified by the laboratory of the plant (cement - 340 kg, sand - 547 kg, crushed stone of a fraction of 5-20 mm - 560 kg, crushed stone of a fraction of 20-40 mm - 840 kg, water - 170 kg) plant productivity will be.

I. SCOPE

The technological map is developed on the basis of the methods of scientific organization of labor and is intendedfor use in the development of a project for the production of work and the organization of labor at mixing plants for the preparation of cement concrete mixtures.

The following basic conditions are accepted in the map.

The automated plant with a mixing plant SB-78 operates in the general complex of machines and mechanisms forabout the device of cement-concrete pavements of highways.

The consumable storage of sand and graded crushed stone of an open type with dividing walls is located next to the mixing plants. Hand the stock of materials must be created in the warehouse, sufficient for the operation of the installations within 10 days. Sand and fractionated crushed stone are delivered to the supply warehouse in railway cars or by road. In the case of delivery of unfractionated or contaminated crushed stone, washing and sorting of the material into fractions should be organized. Sand and crushed stone are fed into the feeders of the batching department by bucket loaders of the TO-18 or "Case" type.

The mixing plant is supplied with cement from a consumable warehouse with a capacity of 300 tons.

Cement is delivered to the consumable warehouse by cement trucks.

The site of the plant has a hard surface, drainage is provided. The territory of the plant is fenced temporary fence. To the plant underprovided water and electricity.

A hard-surfaced access road has been laid to the mixing plant. The movement of cars is organized according to the ring scheme without oncoming traffic.

For the export of cementa column of dump trucks with an estimated number of vehicles is fixed to the concrete mixture.

The number of vehicles is adjusted depending on the distance of transportation of the mixture and road conditions.

In technological The map provides for a plant capacity of 320 m 3 per shift.

When changing the conditions accepted in the technological map, it is necessary whenknitting it to new conditions.

. MANUFACTURING PROCESS INSTRUCTIONS

Automated cementobetonne plant (TsBZ) with the SB-78 plant is designed for the preparation of rigid and plastic concrete mixes with sizes of aggregate fractions up to 40 mm .

Technical specifications

Prod driving, m 3 / h ............................................... ........ 60

Fra quantity pieces of aggregates:

sand................................................. .......................... one

rubble n................................................. ......................... 3

The largest th placeholder size, mm................................... 70

Feed hopper capacity, m 3

filled threads ................................................. ............ 36

cement a................................................. ...................... 12

Mouth new power, kW ............................................... 57,8

Dimension dimensions, mm:

dl ina ................................................. ......................... 36800

width................................................. ....................... 2600

height................................................. ......................... 12520

The weight, t....................................................................................... 3

Installation and consists of the following main blocks (see figure):

continuous concrete mixer, the working body of which is square-section shafts with cast blades made of steel 35 GL mounted on them. work surfaces lothe mouths are located at an angle of 45° relative to the axis of the shaft;

supply hopper of cement, which is a cylindricala conical container and a dispenser designed to receive cement and feed it with cement. The bunker is equipped with a filter for cleaning the exhaust air before it is released into the atmosphere and automatic indicators of the lower and upper levels;

dosing unit, consisting of four consumable buanchors for crushed stone and sand with dispensers. A B-21 vibrator is fixed on the inclined wall of the sand bin. The batchers are mounted above the horizontal collection conveyor, which transports the materials to the inclined conveyor and then to the concrete mixer.

Technological scheme of work of the pulp and paper mill with mixer SB-78:

Notes. one . The numbers above the line are the duration of operations in minutes.

Description of works

The composition of the link (team)

unit of measurement

Scope of work

Norm of time

Price, rub.-kop.

Standard time for the entire scope of work,people-h

The cost of labor costs for the entire scope of work, rub.-cop.

Local norm SU-921 of the trust "Dondorstroy"

Checking SB-78 nodes before starting work. Ce dispenser settingment and checking the operation of all dispensers. Checking the operation of nodes idle. Checking the quality of produced concrete and adjusting the supply of water and cement. Preparation and production of ready-mixed concrete in automatic mode. Tidying up workplaces and mixing plant at the end of the shift. Plant maintenance, monitoring technical condition power equipment

Mixing plant operator 6 years - one

Assistant driver (construction locksmith) 4 times. - one

Front loader driver "Case" 6 years. - 1

Cement supply fitter 4 size. - one

Road worker for the maintenance of batchers of inert materials 3 category. - 1

Electrician 5th category - one

100 m 3

15,6

10-62

99,84

67-97

Total: 640 m 3

99,84

67-97

per 100 m 3

15,6

10-62

. TECHNICAL AND ECONOMIC INDICATORS

unit of measurement

According to calculation A

Schedule B

How much % is the indicator according to the graph more (+) or less (-) than according to the calculation

work hard bone works at 100 m 3 mixtures

people-h

15,6

Average rank of workers

Average week daily wage per worker

rub.-kop

TYPICAL TECHNOLOGICAL CHART (TTK)

APPLICATION OF CONCRETE WITH ANTI-FROST ADDITIVES

1 area of use

1.1. The technological map was developed for concreting structures winter conditions with the use of antifreeze additives.

1.2. Winter conditions are conditions under which the average daily outdoor temperature is below 5 °C and the minimum daily temperature is below 0 °C.

1.3. The essence of the method of introducing antifreeze additives into the concrete mixture consists in introducing into the concrete mixture during its manufacture additives that lower the freezing point of water, ensure the hydration reaction of cement and its delayed hardening at low temperatures.

1.4. Antifreeze additives are used in the case of a device during the construction in winter conditions of monolithic concrete and reinforced concrete structures, monolithic parts of prefabricated monolithic structures, embedding the joints of prefabricated structures.

1.5. The scope of work under consideration technological map includes:

Laying of concrete mix with antifreeze additives;

1.6. Concreting in winter conditions with the use of antifreeze additives is carried out in accordance with the requirements of federal and departmental normative documents, including:

SNiP 3.03.01-87. Bearing and enclosing structures;

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

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

- "Guidelines for the production of concrete work in winter conditions, areas of the Far East, Siberia and the Far North." Moscow, Stroyizdat, 1982;

- "Manual for the production of concrete work." Moscow, Stroyizdat, 1975;

- “Guidelines for quality control of construction and installation works”, St. Petersburg, 1998.

2. Organization and technology of work performance

2.1. Prior to the start of the installation of a robot for the use of concrete mixtures with antifreeze additives in winter conditions, it is necessary:

Execute and accept the underlying structures;

Prepare tools, fixtures, inventory;

Deliver to workplace materials and products,

Instruct workers on labor protection;

Familiarize the performers with the technology and organization of work.

2.2. The use of concrete mixtures with antifreeze additives includes:

Selection of antifreeze additives;

Preparation of concrete mix with antifreeze additives;

Transportation of concrete mix with antifreeze additives;

Laying concrete mix with antifreeze additives;

Curing of concrete with antifreeze additives;

Quality control and acceptance of works.

2.3. As antifreeze additives, it is possible to use chemicals, the characteristics of which are given in Table. 2.1. It is recommended to use complex additives containing compatible plasticizing and antifreeze (simultaneously accelerating hardening) components.

2.4. The scope of concrete with antifreeze additives and hardening accelerators are given in table. 2.2.

2.5. The antifreeze additives listed above have a different mechanism of influence on the process of concrete structure formation. Some of them only reduce the freezing point of water and do not affect the rate of setting and hardening of concrete (for example, HH, M).

Other additives, along with effective antifreeze properties, are simultaneously setting accelerators (P) and hardening accelerators (NK, NNK). Approximate strength of concrete with antifreeze additives is given in Table 2.3.

2.6. The optimal amount of antifreeze additive depends on the minimum temperature of the concrete mixture. When curing concrete with antifreeze additives, it is necessary to create such conditions that during the period of transportation and laying the concrete mix does not cool below 0°C. In this case, the optimal amount of antifreeze additives should correspond to the data in Table. 2.4.

2.7. Concrete mixtures with NK, NNKi, especially P additives are characterized by accelerated setting times, which makes it difficult to lay the concrete mixture and degrade the structure. cement stone. Therefore, simultaneously with the indicated antifreeze components, it is recommended to introduce plasticizing agents into the composition of the concrete mixture. As a plasticizing component of the complex additive, which increases the mobility and reduces the water demand of the concrete mixture, it is recommended to use the additives given in Table. 2.5.

Concrete with the addition of potash during setting and initial hardening must have negative temperature.

2.6. The most effective complex additives are compositions that include surface-active substances (surfactants) and electrolytes. With properly selected dosages of electrolyte and surfactant additives, it is possible to use the plasticizing properties of the latter and at the same time obtain a high hardening rate. The list of the most effective complex antifreeze additives and their reduced amount is given in Table. 2.5.

2.7. The recommended amount of chemical additives for complex curing of concrete is given in Table 2.6. The use of concrete with antifreeze additives should be preceded by laboratory tests of the effect of additives on the strength and hardening rate of concrete.

2.8. The final choice of the type of chemical additives is made taking into account the prices of manufacturers and suppliers of chemical additives.

2.9. The preparation of the concrete mixture is organized at a concrete plant. The selection of the concrete composition for winter laying is carried out in accordance with GOST 27006-86. The selection of the composition is carried out by a calculation-experimental method, which includes the solution of the following issues:

Determination of all requirements for the quality of the concrete mix and concrete;

Quality assessment and selection of materials for the preparation of concrete mix;

Calculation of the nominal composition of concrete;

Experimental verification of the design composition;

Adjustment of the composition and calculation of the production composition of concrete.

2.10. When preparing a concrete mixture, it is possible to heat the mixing water, warm or heat the components, as well as heat the concrete mixing unit, batching and bunker compartments.

2.11. To obtain the maximum temperature of the concrete mixture at the outlet of the concrete mixer, water is heated up to the maximum possible temperature of + 80 ° C.

2.12. The mixing time of the concrete mixture in the concrete mixer should be 25% longer than in summer conditions, and not less than the values given in Table 2.7.

2.13. The amount of chemical additives established in accordance with the recommendations is introduced during the preparation of concrete mixtures in the form of aqueous solutions of a working concentration. Salt solutions are prepared on water heated to 40 ° C in mixers. The main indicators of aqueous solutions of antifreeze and plasticizing additives are given in table. 2.8, table 2.9.

2.15. Transportation of the prepared concrete mix is carried out by truck mixers. To minimize heat loss, the open parts of the mixer truck drum are covered with moisture-proof materials and insulated. The neck of the mixer truck drum is insulated and covered with a heat-insulating cover or the neck is heated with exhaust gases from the engine. When using only potash, it is recommended to add it at the facility by introducing an aqueous solution of potash with mixing of all components in the mixer truck drum. protected from wind and precipitation. The bunker for supplying the concrete mixture must also be insulated.

2.16. When using concrete pumping plants to supply the concrete mixture, all components and parts in contact with the concrete mixture are insulated. At the same time, especially carefully insulate the pipelines and the main components of the concrete pump in order to maintain the initial temperature of the concrete. At extreme temperatures down to -40°C, in addition to the insulation of the main components of the concrete pump, additional heating of the insulated concrete pipeline is required with flexible heating elements. It should also provide for hot water in insulated tanks for flushing concrete pipelines after concreting.

2.17. Keeping monolithic concrete and reinforced concrete structures erected from concrete with antifreeze additives is carried out in compliance with the following guidelines:

Concrete surfaces that are not protected by formwork, in order to avoid moisture loss or increased moisture due to atmospheric precipitation, should be immediately covered with a layer after concreting waterproofing material(polyethylene film, rubberized fabric, roofing material, etc.);

Concrete surfaces that are not intended in the future for a monolithic connection with concrete or mortar can be coated with film-forming compounds or protective films (bitumen-ethinol, etinol varnish, etc.);

In the event of an unexpected decrease in the temperature of concrete below the design structure, it is necessary to insulate or heat it until the concrete reaches critical strength.

2.18. Demoulding of load-bearing concrete and reinforced concrete structures should be carried out after the concrete reaches the strength given in Table. 2.9.

2.31. If it is impossible to provide the required strength of concrete by the time the structure is loaded with a standard load, it is allowed, with an appropriate feasibility study, to use a concrete class increased by one step.

2.32. It is allowed to remove the formwork, which perceives the mass of concrete of structures reinforced with load-bearing welded frames, as well as side elements that do not bear the load from the mass of structures, after the concrete reaches critical strength.

2.33. The strength of concrete before stripping must be confirmed by tests.

2.34. Removal of thermal protection and formwork from structures, when using concrete with antifreeze additives - upon reaching the strength specified in section 3.

3. Requirements for the quality and acceptance of work

3.1. When curing concrete with antifreeze additives in winter conditions, production quality control is carried out, which includes:

Input control of materials for the preparation of concrete mix, reinforcement and embedded parts, thermal insulation materials;

Operational control of the performance of reinforced concrete works;

Acceptance control of work performed.

At all stages of work, inspection control is carried out by representatives of the technical supervision of the customer.

3.2. The input quality control of materials, semi-finished products, products and parts consists in checking by external inspection their compliance with GOSTs, TUs, project requirements, passports, certificates confirming the quality of their manufacture, completeness and compliance with their working drawings. During the input control, compliance with the rules for unloading and storage is also checked. Input control is performed by line personnel when materials, structures, products arrive at the construction site.

3.3. Operational control should be carried out during the performance of reinforced concrete work and ensure the timely detection of defects and the adoption of measures to eliminate and prevent them. During operational control, they check the compliance of the work performed with the working project and regulatory requirements. Main goals operational control:

Compliance with the technology of performing reinforced concrete works;

Ensuring compliance of the work performed with the project and the requirements of regulatory documents;

Timely detection of defects, their causes and taking measures to eliminate them;

Performing subsequent operations after the elimination of all defects made in previous processes;

Increasing the responsibility of direct executors for the quality of their work.

3.4. When laying the concrete mixture, it is necessary to control:

The quality of the concrete mixture;

Rules for unloading and distribution of concrete mix;

The temperature of the concrete mixture;

Concrete compaction mode;

The order of concreting and ensuring the solidity of the structure;

Timeliness and correctness of sampling for the manufacture of control samples of concrete.

3.4. When laying and compacting a concrete mixture with antifreeze additives, laid in winter conditions, the requirements given in Table. 3.1.

3.5. When curing concrete with antifreeze additives, the following is controlled:

Maintenance of temperature and humidity conditions;

Protection of hardening concrete from mechanical damage;

curing time of concrete.

3.6. Technical requirements when curing concrete with antifreeze additives are given in table. 3.2.

3.6. Concrete quality control provides for checking the compliance of the actual compressive strength of concrete in the design with the design and specified in the terms of intermediate control. The compressive strength of concrete should be checked by testing control cubes with dimensions of 100x100x100 mm in accordance with GOST 10180-90. Test specimens are made from samples of the applied concrete mix. Samples are taken at the place of preparation of the concrete mixture and directly at the place of concreting.

At least two samples should be taken at the concreting site. From each sample, one series of control samples is made (at least three samples in a series). Control samples are concreted in detachable steel molds corresponding to GOST 22685-89. Before concreting, the inner surfaces of the molds are lubricated. The concrete mixture is placed in the molds immediately after sampling with compaction by bayoneting or vibrating. Control samples are stored under the conditions of hardening of the concrete structure. Demoulding the samples after keeping the structure.

The terms for testing control samples are assigned by the construction laboratory, taking into account the achievement by the time of testing design strength. Samples stored in frost must be kept for 2 ... 4 hours at a temperature of 15 ... 20 degrees C before testing. Intermediate control is carried out after the temperature has dropped to the calculated final temperature.

3.7. When accepting a sustained design, check:

Compliance of the design with working drawings;

Conformity of concrete quality to the project;

The quality of the materials used in the construction, semi-finished products and products.

3.8. The requirements for the finished design are given in Table. 3.3.

...

7. Productivity of transport of cyclical action, the method of its calculation. Soil transportation by cyclic transport

8. Methods for the production of earthworks and the conditions for their use.

9. Technology of soil development by excavators with working equipment "dragline"

10. Technology of soil development by excavators with working equipment "straight shovel"

11. Technology of soil development with working equipment "backhoe"

12. The performance of single-bucket excavators, the method of its calculation and ways to improve it

13. Technology of soil development by bulldozers. Development methods, schemes of working movements and their characteristics

14. The performance of bulldozers, the method of its calculation

15. Technology of soil development with scrapers. Methods of development, schemes of working movements and their characteristics.

17. Factors affecting the intensity of soil compaction and their characteristics

18. Methods of soil compaction, their characteristics and conditions of use

19. Technology of soil compaction by machines of static and dynamic action

21. Technological features of soil development in winter

22. Technology for the preparation of concrete mix

23. Technology of laying concrete mix in concreting blocks.

26. Defects in concrete masonry and ways to eliminate it. Concrete care

27. Quality control of concrete work

28. Pile driving technology

29. Stuffed pile technology

30. Acceptance of pile work. Quality control

31. Basic technological schemes for the installation of reinforced concrete structures

32. Scope of work for the installation of welded structures at the construction site

33. Features of the installation of reinforced concrete structures in winter conditions

36. Masonry production technology

36. Features of stone work in winter

37. Purpose and types of waterproofing works (gir)

38. Technology for the production of waterproofing works

39. Technology of production of thermal insulation works.

40. Features of the production of weights in winter conditions

41. Features of the thermal insulation device in winter conditions.

42. Types of roofs and roofing technology

43. Features of work on the installation of the roof in winter conditions

44. Technology of preparing surfaces for plastering and plastering surfaces

45. Features of the production of plaster work in winter conditions

46. Production of works on facing buildings with various materials

47. Features of the production of facing works in winter conditions

48. Surface preparation, application and processing of prepared layers for painting

49. Painting of internal and external surfaces of structures

50. Technology of pasting surfaces with wallpaper

51. Painting and wallpaper work performed in winter conditions

52. Technology of flooring from various materials

53. Construction technology of subgrade and pavement (improved capital and transitional types)

54. Pavements with transitional types of pavement.

55. Improved types of pavement.

56. Quality control in road construction

57. General provisions for the reconstruction of buildings and structures.

58. Dismantling and liquidation of buildings and structures

59. Concrete and reinforced concrete works

60. Dismantling of building structures. Strengthening building structures

22. Technology for the preparation of concrete mix

The technological process of concreting structures includes the preparation of the concrete mixture and its transportation to the object under construction, its supply, distribution, laying and compaction in the structure, the care of concrete during the hardening process.

Concrete mixture cannot be prepared in advance and transported over long distances. After preparation, it must be delivered and placed in the blocks of the structure before setting begins (usually 1 ... 3 hours). Therefore, the concrete mixture must be prepared near the places of its laying so that the time it takes to travel in the summer does not exceed 1 hour.

The concrete mixture is prepared in a mechanized or automated concrete plant in ready-made delivered to the construction site or prepared on-site inventory (mobile) concrete mixing plants.

Preparation of concrete mix consists of the following operations: reception and storage of constituent materials (cement, aggregates), weighing (dosing) and mixing them with water and issuing the finished concrete mixture to vehicles. In winter conditions, additional operations are included in this technological process.

The concrete mixture is prepared according to the finished or dissected technology. With the finished technology, a ready-made concrete mixture is obtained as a product, with a dissected one, dosed components or a dry concrete mixture are obtained. Main technical means for the release of the concrete mixture are supply bins with distribution devices, batchers, concrete mixers, systems of internal vehicles and communications, a dispensing bin.

Technological equipment of a stationary type for the preparation of a concrete mixture can be solved according to one-stage and two-stage schemes.

The single-stage (vertical) scheme (Fig. 6.1, a) is characterized by the fact that the constituent materials of the concrete mixture (binders, aggregates, water) rise to the top point of the technological process once and then move down under the action of their own gravity during the technological process. Advantages: compact, economical, and disadvantages - the complexity of installation (due to the considerable height, up to 35 m).

With a two-stage (parterre) scheme (Fig. 6.1, b), the rise of the constituent materials of the concrete mixture occurs twice, i.e. the components of the concrete mixture are first lifted into the feed bins, then they fall by gravity, passing through their own dispensers, fall into a common receiving funnel and rise again to be loaded into the concrete mixer. The advantage of this scheme is the lower installation cost, and the disadvantage is big square buildings.

When the need for a concrete mix is not more than 20 m 3 / h, mobile mobile concrete mixers with gravity-type mixers are usually used.

Rice. 6.1. Layout diagrams of concrete mixing plants and installations: a - single-stage; b - two-stage; 1 - aggregate storage conveyor

in consumable bunkers; 3, 9, 10 - rotary guide and distribution; 4 - consumable bins; 5 - cement supply pipeline; 6 - cement dispenser; 7 – filler dispenser; 8 - water dispenser; 11 - concrete mixers; 12 - distributing hopper; 13 - concrete truck; 14 - cement truck; 15 - skip hoist.

The design of concrete mixing plants allows you to transfer from working to transport position during one work shift and transport them on a trailer to the next object. The use of such installations is expedient on large dispersed objects located from stationary concrete plants at distances exceeding technologically permissible.

Concrete plants usually produce two types of products - dosed components and ready-mixed concrete.

Cyclic and continuous mixers are used as equipment for the preparation of ordinary concrete mix.

Cyclic concrete mixers differ in the volume of the finished mixture dispensed in one batch.

The performance of the cyclic concrete mixer

P \u003d q n k in / 1000, m 3 / h

where q is the volume of the finished concrete mix for one batch, l; n is the number of batches per hour; k in - the coefficient of use of the concrete mixer in time (0.85 ... 0.93).

The loading of the cyclic concrete mixer is carried out in the following sequence: first, 20 ... 30% of the required amount of water, then simultaneously begin to load cement and aggregates, without stopping the supply of water to the required amount. The cement enters the mixer between the batches of aggregate, thereby eliminating its spraying. The duration of mixing the concrete mixture depends on the capacity of the mixer drum and the required mobility of the concrete mixture and ranges from 45 to 240 s.

Continuous concrete mixers are produced with a capacity of 5, 15, 30 and 60 m 3 / h, and gravity-type machines with a drum mixer - with a capacity of 120 m 3 / h. The duration of mixing in these concrete mixers is indicated in the passports of the machines.

When preparing a concrete mix using a separate technology, the following procedure must be observed: water, part of the sand, finely ground mineral filler (if used) and cement are dosed into the mixer. All these components are thoroughly mixed, the resulting mixture is fed into a concrete mixer, pre-loaded with the rest of the sand and water, coarse aggregate, and once again the whole mixture is mixed.

The composition of the concrete mixture must provide the properties specified for it, as well as the properties of the hardened concrete.

There are certain requirements for concrete mix:

1) it must maintain uniformity (during transportation, reloading and laying in the formwork), which is ensured by cohesion (non-separation) and water-holding capacity. All this is achieved by the correct selection of the composition of the mixture, the accuracy of the dosage of the components and the thorough mixing of all components;

2) be workable. Workability is the ability of a concrete mixture to spread and fill a mold under the action of vibration. It depends on the grain composition of the mixture, the amount of water, the degree of reinforcement, methods of transportation and compaction of the mixture.

Dry mortar(ССС) - a mixture of binder, aggregates, additives, pigments, dosed and mixed at the factory, and mixed with water before use. Accurate dosing of components allows you to get higher specifications finished products compared with mixtures obtained, prepared at the construction site. An important advantage of dry mixes is the possibility of adding chemical additives and microfillers to them, both improving their structure and prepared for use in the cold season.

Concrete Mix Transportation Technology

Transportation of concrete mix includes its delivery from the place of preparation to the construction site, the supply of the mixture directly to the place of laying, or its reloading onto other vehicles or devices, with the help of which the mixture is delivered to the concreting unit. A concreting block is a structure prepared for laying a concrete mix or a part of it with an installed formwork and mounted reinforcement.

In practice, the process of delivering the concrete mixture to the concreting blocks is carried out according to two schemes:

From the place of preparation to direct unloading into the concrete block;

From the place of preparation to the place of unloading at the concrete object, with the subsequent supply of concrete to the concreting unit. This scheme provides for intermediate unloading of the concrete mix.

Transportation and laying of the concrete mixture must be carried out by specialized means that ensure the preservation of the specified properties of the concrete mixture.

Transportation of the concrete mix from the place of preparation to the place of unloading or directly to the concreting unit is carried out mainly by road, and transportation from the place of unloading to the concreting unit is carried out in buckets by cranes, lifts, conveyors, concrete pavers, vibratory feeders, motor carts, concrete pumps and pneumatic blowers.

The method of transporting the concrete mixture to the place of its laying is chosen depending on the nature of the structure, the total volume of the laid concrete mixture, the daily requirement, the transportation distance and the lifting height. With any method of transportation, the mixture must be protected from atmospheric precipitation, freezing, drying, and also from the leakage of cement laitance.

The permissible duration of transportation depends on the temperature of the mixture at the outlet of the mixer: it should not exceed 1 hour at a temperature of 20-30°C; 1.5 h - 19-10°C; 2 h - 9-5°С. Long-term transportation on bad roads leads to its delamination. Therefore, in vehicles without stirring the mixture along the way, it is not recommended to transport more than 10 km on good roads and more than 3 km on bad roads.

Choice of vehicles carried out on the basis of the conditions of the facility under construction: the volume of concrete work; the period of their production; travel distances; the size of the building in plan and in height; TEP (productivity, speed of movement, unit cost of transportation). In addition, it is also necessary to take into account the requirements for maintaining the properties of the concrete mixture - preventing decay, changes in uniformity and consistency.

To transport the mixture to the site, road transport is widely used - general-purpose dump trucks, concrete trucks and concrete mixer trucks (mixers).

Transportation of the mixture by dump trucks. Disadvantages: there are difficulties in protecting the mixture from freezing, drying, leakage of cement milk through the cracks in the bodies, the need for manual cleaning of the body.

Transportation of concrete mix by concrete trucks , equipped with sealed dump-shaped tipping bodies. Advantages: transportation of the mixture is possible at a distance of up to 25-30 km, and without splashing it and leaking cement laitance.

Transportation of the mixture by truck mixers (mixers). This is the most effective remedy transportation. Concrete mixer trucks are loaded with dry components at the factory and prepare the concrete mix en route or at the construction site. The capacity of truck mixers for the finished mix is from 3 to 10 m 3 . Mixing of components with water usually starts 30-40 minutes before arrival at the site. In truck mixers (mixers) it is also advantageous to transport ready-made concrete mixtures due to the possibility of inducing them along the way due to the rotation of the drum. Advantages: the range of transportation of dry mix components in truck mixers is not technologically limited.

The concrete mixture delivered to the facility can be unloaded directly into the structure (when concreting structures located at ground level or shallow) or reloaded into intermediate containers for subsequent delivery to the concreting site.

The mixture is fed into the structures to be concreted by cranes in fixed or rotary buckets or by belt conveyors (conveyors), concrete pumps and pneumatic blowers (through pipes), link arms and vibrating arms, belt concrete pavers. Rotary tubs with a capacity of 0.5 - 8 m 3 are loaded directly from dump trucks or concrete trucks. Belt mobile conveyors are used when it is difficult or impossible to supply the mixture to the place of laying by means of delivery or in tubs. Conveyors up to 15 m long serve the mixture to a height of up to 5.5 m. To reduce the height of free fall of the mixture during unloading, guide shields or funnels are used. Disadvantage: The conveyors need to be changed frequently during the concreting process.

Therefore, self-propelled belt trucks are more effective in this regard. pavers mounted on a tractor, equipped with a skip hoist and a belt conveyor up to 20 m long. To supply the mixture in structures located in cramped conditions and in places not accessible to other means of transport, they are used concrete pumps. They supply the mixture through a steel detachable pipeline (concrete pipe) to a horizontal distance of up to 300 m and vertically up to 50 m. Also, for non-overload supply of the mixture and its laying, pneumatic superchargers. The maximum range of transportation by them is 200 m horizontally or up to 35 m vertically when supplying up to 20 m 3 / h. To supply and distribute the mixture directly at the installation site at a height of 2 - 10 m, apply trunks, representing a pipeline of conical metal links and an upper funnel; vibration robots, representing a link trunk with a vibrator. On the loading funnel with a capacity of 1.6 m 3 and sections of the vibro-shoe with a diameter of 350 mm, vibrators-stimulators, as well as dampers, are installed every 4-8 m.

The supply and distribution of the concrete mixture in the structure at a distance of up to 20 m with a slope of 5-20 ° to the horizon is ensured by vibration chutes in conjunction with vibration feeder with a capacity of 1.6 m 3. They can lay mixtures up to 5 m 3 /h at an angle of inclination of 5 °, and at an angle of 15 ° - up to 43 m 3 / h.