Cast in place concrete frame structure construction technology

Pouring concrete frame structure construction

1 scope

This technology is applicable to General cast frame and frame-shear wall concrete pouring works.

2 construction preparation

2.1 materials and equipment:

2.1.1 cement: No. 325 more slag Portland cement or Portland cement. Entry must have a quality certificate and retest report.

2.1.2 sand: appropriate uses of coarse sand or sand. When the concrete below the C30, clay is less than 5%, above, the C30 is not greater than 3%.

2.1.3 stone: size of 0.5~3.2cm, concrete below the C30, clay is less than 2%, above, the C30 is not greater than 1%.

2.1.4 admixture fly ash, their content should be determined by experiments, and should comply with the relevant standards.

2.1.5 concrete admixtures:, early strength water reducing agent agent shall conform to the provisions of the relevant standards, its volume after the tests to meet the requirements, can be used.

2.1.6 major equipment: concrete mixers, scales (or automatic metering device), two-wheeled carts, small dumpers, sharp spade, shovel, concrete skip, plug-in vibrators, long wooden trowel, float, plug the iron foot, rubber pipes, iron plate, barrel, tower cranes, and so on.

2.2 operating conditions.

Paragraph 2.2.1 pour concrete floor formwork, reinforcement, embedded and pipe, and all installed and inspected in accordance with the design requirements and through hidden, preflight procedures.

2.2.2 concrete shelf and Ma has pitched a complete and inspected.

2.2.3 cement, sand, stone and additives have been examined in accordance with the relevant standards, the laboratory has issued notice of concrete mix.

2.2.4 scales (or automatic feeding system) approved by the inspection accuracy in measuring vibrator (bar) by commissioning qualified.

2.2.5 personnel according to the construction plan of action team has conducted a comprehensive construction technology to give the low-down, concrete applications have been approved.

3 operational processes

3.1 process;

Ready concrete concrete mixer → → transport →

Columns, beams, slabs, shear walls, stairs, concrete pouring and tamping → maintenance

3.2 job preparation: before pouring in the template should be rubbish, dirt and other debris and oil on the bar clean and check the pad mat reinforced cement mortar well. Water the wood template should be used to make a template and moist. Cleaning of the column template should be closed after clearing debris and water. Scissors scrape loose concrete walls have been clean.

3.3 concrete mixer:

3.3.1 each according to the mix a variety of material content and weight of the vehicle, individual scales are fixed well cement, sand, stone standard. Trucks weighing at feeding time, determination of water should frequently aggregates, adjust the mix of water and ensure water accurately.

3.3.2 charging sequence: the first stone, and then loaded cement, and finally pour sand. When extra fly ash admixture should be joined together with cement. If additive (reducing agent, light intensity, such as), the powder should be processed according to each amount put into a small bag (plastic bags) and available simultaneously with the coarse and fine aggregates to join; amount of liquid should be per plate and water and mount the mixer.

3.3.3 time: for concrete mixing, since all the mixture into the mixing Drum plays a concrete start discharging, concrete mixing and the minimum amount of time, according to table 4-34.

Concrete mixing time (s) in table 4-34

Mixer discharge capacity (l)

<250 250~500 >500

Since falling 90 120 150

Forced 60 90 120

Since falling 90 90 120

Forced 60 60 90

3.3.4 concrete starting stirring time, by a competent technical department, foreman of the construction unit employees concerned, the plate of concrete slump and workability for identification, check compliance with notice requirements, adjusted qualified and stir again.

Transportation of concrete: concrete mixer after unloading, pouring should be sent to the site. In the course of transport, to prevent segregation of the concrete, cement paste loss, slump and the initial setting and so on. Such as the transport of concrete pouring sites when there is segregation, prior to pouring the second mix.

Finished pouring concrete after discharge from the mixer to the extension of time should not be more than provided in table 4-35.

Finished pouring concrete from the mixer unloading to time (min) table 4-35

Less than 25 above 25

<C30 120 90

<C30 90 60

Note: mixed use high early strength cement or admixtures mixed concrete should be determined according to the test.

You must ensure concrete pump to pump concrete work, if a failure occurs, segregation phenomenon in a pause longer than 45min or concrete, should immediately wash the tube with water pressure or some other method of residual concrete.

3.5 concrete pouring and tamping General requirements:

3.5.1 lean concrete of a skip falling free falling height must not exceed 2m, you must take measures to pouring exceeds 3M, with a series of barrel or chute.

3.5.2 concrete should be segmented layer continuous, LIFT height should be based on structural features, the reinforcement density decides, for the length of the vibrator part l. 25 times times the maximum of 50cm.

3.5.3 using vibrating needle quickly inserted slowly remove, insert point to evenly arrange, point-by-point move, the order shall not be omitted, even tapped. Mobile space with a little Yu Zhen during the radius of 1.5 times (typically 30~40cm). Layer on the vibration should be inserted in the lower 5cm, to eliminate the seam between the two layers. Surface vibrators (or plate vibrator) of the mobile space, should ensure that vibration plate cover has been tapped for part of the edge.

3.5.4 casting concrete should be carried out continuously. If it is necessary to break, the rest period should be as short as possible, and before the front layer concrete setting, a secondary layer finished pouring concrete. Cement used for the longest time interval according to the variety, temperature and concrete setting conditions, General 2H treatment of construction joints.

3.5.5 should always observe the template when pouring concrete, reinforcement and reserve holes, such as embedded parts and reinforcing any move, deformation, or jams, found that the problem should be dealt with immediately and should be amended before poured concrete setting intact.

3.6 concrete pouring of the columns:

3.6.1 column should fill at the bottom before pouring to 5~10cm thickness and concrete the same reduced stone mortar, concrete layer vibrating, vibrating needle thickness of each layer is not more than 50cm, vibrator must not touch of steel and embedded parts. Above, vibrating, but somebody has to knock at any time below the template.

3.6.2 height in 3M, top in ash poured directly over 3M, measures should be taken (in barrels) or subparagraph on the template side door hole Setup inclined chute pouring. Height of 2m in each paragraph, each block of concrete after the doors closed tight hole template and hoop hoop in prison.

3.6.3 finished pouring concrete pillars, if you need construction joints should remain under the main beam. Beamless floor slab should stay below the CAP. And when the slab casting, should stop l~1.5h after finished pouring columns, making it an initial heavy, and then continue to pour.

3.6.4 After pouring out, should be kept out of the lap bar arrangement in place.

3.7 beams and slabs of concrete pouring:

3.7.1 beams and slabs should be pouring, pouring method should begin by the end of "method", that is, placing beams, according to beam high stratified placement into stepped, when bottom position and pouring of the concrete, with ladder extended, continuous beams and slabs of concrete pouring forward.

3.7.2 and overall height of plate is connected to a beam greater than LM, allowing separate pouring, construction joints should remain in the plate under the bottom of 2~3cm. Poured pound Shi, pouring and vibration pound must close tie, first layer Xia material slow some, breast full vibration real Hou again Xia two layer material, with "catch pulp method" keep water mud along beam end of package stone forward advance, each layer are should vibration real Hou again Xia material, breast and the beam help parts to note vibration real, vibration pound Shi shall not touches steel and the pre buried pieces.

3.7.3 beam when the reinforcement is key, here pouring concrete for the times using small particle stones with the strength of concrete using small diameter vibrator vibrating.

3.7.4 deficiency of pouring concrete floor thickness should be slightly greater than the plate thickness, vibrating back and forth with vibrating Board perpendicular to the casting direction, plates available internal vibrator smooth pouring Tora vibrating, and plug the iron ruler to check the concrete thickness, vibration is finished with a long wooden trowel smooth. Construction joint or be embedded parts and reinforcing with a wooden float level. Pouring concrete vibrator is not allowed when casting concrete.

3.7.5 construction joint locations; suitable for pouring floor slab along the beam direction, construction joints should be retained in the center of beam span the range 1/3. Construction joints surfaces should be perpendicular to the axis of the beam or Board shall not be inclined Cha. Construction joints should be treated with wood or steel mesh out of prison.

3.7.6 construction joints subject to compressive strength of concrete not less than 1.2MPa, only allowed to continue pouring. Before continuing to pour concrete, construction joints of concrete surface should be cutting hair, eliminate the floating stones and water rinse, pour a layer of cement slurry, and then continue to pour concrete, detailed operation of compacting, combining new and old concrete.

3.8 pouring concrete shear wall:

3.8.1 columns, and walls of concrete strength are the same, can be poured, whereas first pouring of concrete, embedded anchorage reinforcement of shear wall, column model to be demolished, then tying rebar, formwork, pouring concrete shear walls.

3.8.2 wall prior to pouring concrete, evenly at the bottom before pouring 5cm and walls the same ingredients of concrete cement mortar and shovels into the mold, hopper is not applied directly into the mould.

3.8.3 poured wall concrete shall be continuous, interval should not exceed 2H, pouring each layer thickness control in 60cm, therefore must be arranged in advance concrete cutting point and vibrators the operator number.

3.8.4 vibrator move distance should be less than 50cm, vibration every time to float to the surface of pulp, for the upper and lower concrete combined into a whole, vibrator concrete should be inserted in the lower 5cm. Vibrating steel-intensive and when opening, vibration to prevent leakage. In the hole on both sides at the same time vibrated, no ash to approximately the same height. Big hole template should be open by the end of the cave, and vibrating poured here.

3.8.5 after finished pouring concrete wall, hands thrown out of reinforced them with a wooden float elevation line of wall surface of concrete leveling.

3.9 pouring concrete stairs:

3.9.1 stair concrete pouring from the bottom up, compacting concrete, when the time is reached and time pouring with concrete, continuous pushing up, and feel free to use wood trowel (or plastic trowel) will step on the surface smooth.

3.9.2 cast seam: staircases suitable for continuous pouring of concrete finish, multi-layered construction joint of the stairs should be left on the flight 1/3 site.

3.10 maintenance: after the concrete has been poured, and should be covered and 12h water, watering frequency should be able to maintain adequate wetting of the concrete, curing period of not less than 7 days and nights.

3.11 in winter:

3.11.1 pouring of concrete mixed with negative temperature in winter when the composite additives should be according to the temperature difference, the use of different admixtures for negative temperature. And must be approved by a special test before use and unit identification. Columns, and walls conservation conservation should be used properly.

3.11.2 winter construction plan should be developed before winter, heating and mixing of raw materials, transport, placement and maintenance of heat engineering calculation and construction.

3.11.3 before concrete pouring should be clear of ice and snow, dirt on the template and steel. Container for transport and pouring of concrete thermal insulation measures.

3.11.4, conveyance and construction process, the temperature should be consistent with data, as determined by the thermal calculation does not comply, it shall take measures to adjust. When using heat curing, curing temperature shall not be less than 2 degrees before.

3.11.5 overall structure when heat curing and placement procedures and construction joint locations, should be able to prevent large temperature stress, such as heat when temperatures exceed 40 degrees, should seek to design units determined. Raising and lowering the temperature of the concrete shall not exceed the norm.

3.11.6 winter average temperature is-5 ℃, comprehensive thermal storage method of construction is generally used, used by early-strength antifreeze admixtures should be factory-prove, and refer it to the laboratory specimen contrast official after use. Comprehensive thermal storage method should use No. 425 above ordinary Portland cement or r-type early-strength cement. Additives can improve the early strength should be used, and can reduce the resistant freezing critical strength of powder composite admixture, and aggregate and joined to ensure mixing.

3.11.7 winter maintenance: template and its insulation layer should be cooled to 5 c in concrete rear removable. Concrete and the outside temperature is greater than 15 ℃, after the removal of the concrete surface should be temporarily override so that it slowly cooled.

3.11.8 provisions in addition to the normal number of groups produced concrete block, and structure the same curing condition should be added to the second group, a group to test the strength of concrete before freezing, another group to test the strength of conservation at room temperature 28D.

3.11.9 winter construction process, you should complete the "construction of concrete engineering records" and "winter construction of concrete daily."

4 quality criteria

4.1 project:

4.1.1 cement used in concrete, water, aggregates, admixtures must conform to the relevant specifications and requirements, check the certificate or test report in accordance with the quality requirements of the factory.

4.1.2 concrete mix proportion and materials measuring, mixing, conservation and treatment of construction joints must meet the construction specifications.

4.1.3 concrete strength of blocks sampling, production, maintenance and testing to meet the standards for inspection and evaluation of concrete strength (GBJ107-87) requirements.

4.1.4 design crack structure are not allowed, no cracks, design allows structural cracks, the crack width must meet the design requirements.

4.2 basic item: vibration compacting of concrete; without honeycomb, cavities, exposed tendon defects, cracks, inclusions, etc.

4.3 allowable deviation, as shown in table 4-36.

5 finished product protection

5.1 to ensure correct position of steel and blocks shall not step on the floor, stairs of truss bar, do not touch the moving of embedded parts and reinforcing.

5.2 without a heavy impact template, not beams or hanging help pedal step on the stair template, setting should be a springboard to protect firm and strict template.

5.3 stair 3 poured on floors, stair on the upper surface of the concrete to be protected must be concrete strength to 1.2MP. Yihou, operate on and bracket mounting structure and templates.

Cast in place concrete frame tolerance table 4-36

Tolerance (mm)

Single-layer multilayer frame

1 axis displacement 8 5 foot check

Storey ± 10 ± 5

Full height ± 30 ± 30

3 column, wall and beam section dimensions +8-5 ± 5 foot check

Each layer of 5 5

5 column and wall vertical full height H/1000

And not more than 20 H/1000

And no more than 30

5 8 8 2m surface flatness on foot and wedged feeler Gage check

Embedded steel center line position offset of 6 10 10

7 embedded pipe, set aside the hole center line position offset 5 5

Embedded bolt centerline position offset 5 8 5

9 reserved hole Center location offset 15 15

Shaft length and width

Center +25

-0 +25

-0

H/1000

And not more than 30 H/1000

And no more than 30

Note: h-columns, the full height of the wall.

5.4 winter cover in the templates that have been poured, to paving operations on the scaffold, trying not to step foot.

6 quality problems to be noticed

6.1 cellular: why was concrete, material thickness, vibration vibrating false or omitted, template gap loss of cement slurry, rebar closer and concrete slump is too small or too much stone, columns, wall template, there are gaps, so that the mortar in the concrete caused by the emission from below.

6.2 exposed reinforcement: due to the reinforcing pad displacement, distance, left, bars close to the template, causing dew tendons, or vibrating beam and plate the bottom is not solid, exposed tendons may also occur.

6.3 MA: stripping surface brush release agent or stencil or template prematurely moist enough, on the surface of concrete sticking to the template caused pitted and peeling.

6.4 cavities: because the concrete rebar closer was card, continue pouring upper concrete without vibration.

6.5 crack and slag layers: construction joint of clutter, dirty or not end of pouring pulp and other reasons, the gaps, the slag layer.

6.6 connection of beam and column size too large, mainly due to a template column joint stiffness or this site template is not serious about controlling section size.

6.7 in-situ floor slab and on the stair surface flatness deviations are too large: the main reason is that after the concrete has been poured, don't trowel the surface carefully flattened. Winter construction insulation layer in cover, his prematurely or not operate plate.

7 quality records

This standard shall meet the following quality records:

7.1 cement factory quality certificate and enter the second interview report.

7.2 stone test report.

7.3 sand test report.

7.4 admixture quality certificates and entry test reports.

7.5 quality additives and the approaching June test reports, product brochures.

7.6 test of concrete records.

7.7 concrete mix order.

7.8 pressure test for strength of concrete block reports.

7.9 strength assessment of concrete form.

7.10 section for quality inspection and assessment of concrete.

7.11 concrete journal (winter).

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