This project uses commercial concrete, and the concrete pouring adopts a combination of automobile pump and fixed pump.
1.Process.
1) The concrete construction process of walls and columns is shown in the figure below
Figure 66-1 Flow Chart of Wall and Column Concrete Construction.
2) The construction process of sorghum and slab concrete is shown in the figure below
Figure 66-2 Beam and slab concrete construction flow chart.
2.Preparation before concrete pouring.
1) Preparation and inspection of machine tools.
Before pouring concrete, prepare and implement the hopper, vibrator, vibrating rod, concrete pump and other machinery and equipment as needed. For vulnerable machinery and tools, there should be a spare, and the tools used should be inspected and tested before pouring, and full-time technicians should be equipped for maintenance at any time.
2) Guarantee water and electricity**.
During the concrete pouring period, it is necessary to ensure that the water, electricity and lighting on the site are not interrupted. You can contact the water and electricity departments in advance. In order to prevent power outages, a generator is prepared.
3) Stay on top of the weather.
Strengthen the forecast contact with the meteorological department. When pouring concrete in each construction section, grasp the changes in the weather and try to avoid rainy days to ensure the pouring quality of concrete.
4) Check the formwork, brackets, rebar and embedded parts.
Before pouring concrete, the size, specification, quantity and location of formwork, steel bars, steel bones, protective layers and embedded parts should be checked and controlled, and their deviations should meet the requirements of construction specifications. Pay attention to the following points when checking:
1) Whether the elevation, position and cross-sectional size of the template meet the design requirements.
2) Whether the installed bracket is stable;Whether the fixing of supports and formwork is reliable.
3) Before pouring concrete, the garbage and wood chips in the template should be removed.
5) Be technically prepared.
1) Technical disclosure to the construction personnel.
2) Ask the owner and supervisor to accept the hidden part and fill in the concealed acceptance record. Strictly implement the concrete pouring order system.
3) Fill in the concrete mixing notice, and inform the concrete mixing plant to be poured concrete mix ratio, mixing volume, pouring time.
3.Transportation and pumping of concrete.
1) Transportation of concrete.
1) Due to the large construction area, the commercial concrete is transported to the on-site pump truck parking point with a mixer truck, and the transportation time shall not exceed 2 hours, and it is strictly forbidden to add water during the transportation.
2) The speed of the mixer truck should be rotated according to the different requirements of the mixing plant for loading, mixing, unloading, etc., or the requirements of the product manual of the mixer truck, so as to ensure product quality.
2) Concrete pump pipe laying.
1) The straight pipe layout of the concrete conveying pipeline should be straight, the pipe joint should be dense and not leaking, and the anchorage at the turning position should be firm and reliable.
2) The distance between the concrete pump and the vertical upward pipe should be greater than 15m to counteract the anti-fall force and ensure that the vibration of the pump is not directly transmitted to the vertical pipe.
3) Where the position of the pipeline should be flat, the pipeline should be cushioned with brackets or wooden pads, and should not be directly in contact with the formwork and steel bars, and if it is placed on the scaffolding, reinforcement measures should be taken.
4) When the vertical pipe passes through the floor slab, it should be anchored with wooden square or embedded bolts.
5) The newly connected conveying pipe in the middle of construction should be cleared first, and the pipe wall should be lubricated with water or cement mortar.
3) Concrete pumping.
The concrete pumping of this project mainly adopts ground pumps, and the basement and shop parts are assisted by automobile pumps.
1) Before the concrete pumping, the hopper, pump chamber and pipeline of the pump truck are moistened with an appropriate amount of water and the contact parts with the concrete, and after checking that the pipeline is not abnormal, then lubricate and press with 1:1 cement mortar.
2) When starting pumping, the pump should be in a low-speed operation state, and the speed is 500-550r min. It is necessary to pay attention to the pressure of the pump and the working conditions of each part, the conveying pressure is generally not greater than the maximum working pressure of the main cylinder of the pump 1 3, and it can be improved to the normal operating speed only after the smooth pressure is sent.
3) The pumping of concrete should be carried out continuously, when the concrete ** is insufficient or the operation is not normal, the pressure feeding speed can be slowed down to maintain continuous pumping. Slow pumping time, not exceeding the permissible time from mixing to pouring completion.
4) When encountering difficulties in concrete pressure feeding, the pressure of the pump rises, and the pipeline vibrates, do not force the pressure to feed, the pipeline should be checked first, and slow down the pressure feeding speed or reverse the pump to prevent blockage. When the conveying pipe is blocked, you can use a mallet to knock on the pipeline, find out the blocked pipe section, remove the blocked pipe section after the concrete is relieved, take out the blockage, and check whether the rest of the pipeline is blocked, if there is no blockage, then take over. When re-pressurizing, the air must be exhausted before the disassembled pipe section fitting clamp can be tightened.
5) During the pumping process, it should be noted that the concrete in the hopper should not be kept 200mm lower than the upper mouth of the hopper. In case of insuction of air, immediately make the pump run in reverse, and the concrete is sucked into the hopper to remove the air, and then pressurized.
6) In the process of pumping concrete, when the pumping interruption time exceeds 30min or the pressure is difficult, the concrete pump should be pushed at intervals, and 4 strokes are reversed every 4 5min to prevent concrete segregation or blockage.
4.The method of pouring concrete.
The pouring of concrete in this project adopts the construction method of one-time pouring of first wall, column and back beam and slab.
1) Concrete pouring of walls and columns.
1) The concrete pouring of walls and columns should be carried out in layers, the thickness of each layer should not exceed 500mm, and the initial setting time of concrete between the upper and lower layers should not be exceeded, and it is not allowed to leave any horizontal construction joints outside the specifications.
2) For concrete walls and columns with dense steel bars, the pouring point should be left in the process of steel bar binding and marked on the steel bar, and small rods should be selected to vibrate to ensure that there is no vibration leakage.
2) Concrete pouring of beams and slabs.
1) Beams and slabs should be poured at the same time. The concrete of the beam is poured into a stepped shape to advance first, when the elevation of the bottom of the slab is reached, then it is poured together with the concrete of the slab, with the continuous extension of the stairs, the pouring of the slab also keeps advancing, when the beam height is greater than 1m, the beam can be poured separately to the construction joint at 2 3cm below the bottom of the slab, and then the slab is poured.
2) to columns, walls and beams with larger heights, in the slab concrete pouring is completed 1 1After 5 hours, the concrete should be vibrated twice.
3) In order to prevent cracks in the plate, first vibrate with a plug-in vibrating rod and then vibrate with a plate vibrator until the surface is overflowing with slurry, and then roll with an iron roller, before the initial setting, calender with an iron trowel, and finally with an iron trowel before the final setting.
4) The concrete pouring area of this project is large, and the elevation control network should be done to strengthen the flatness control of the floor slab.
5.Vibrating of concrete.
1) When pouring concrete, the correct vibrating method can avoid common quality problems such as honeycomb surface, which must be taken seriously and operated carefully. Walls, beams and columns are all using HZ-50 plug-in vibratorsAt the intersection of beams with each other, the reinforcement is dense, and the Hz6X-30 plug-in vibrator can be used insteadWhen pouring concrete on the floor slab, when the plate thickness is greater than 150mm, a plug-in vibrator is adoptedBut the rod should be inserted obliquely, and then vibrate again with a plate vibrator to level the concrete;When the thickness of the plate is less than 150mm, the plate vibrator is used to vibrate.
2) When using a plug-in vibrator:
1) The correct method of the vibrator should be "fast plug and slow unplug". In the process of vibrating, it is advisable to twitch the vibrating rod up and down slightly, so that the concrete vibrates up and down evenly.
2) When pouring concrete in layers, the thickness of each layer of concrete should meet the requirements of the specification. When vibrating the upper layer of concrete, it should be inserted into the lower layer about 50mm to eliminate the seam between the two layers. At the same time, when vibrating the upper layer of concrete, it should be carried out before the initial setting of the lower layer of concrete.
3) Each insertion point should master the quasi-vibration time, too short is not easy to compact, too long can cause concrete segregation. Generally, the surface of the concrete should be level, no longer significant settlement, no longer bubbles and the surface of the mortar shall prevail.
4) The insertion points of the vibrator should be evenly arranged, and the order of "determinant" or "staggered" can be used, but they cannot be mixed. The distance of each moving position should not be large to 15 times.
5) When the vibrator is used, the distance between the vibrator and the template should not be greater than 0 of the radius of the vibrator5 times, can not be close to the formwork, and try to avoid steel bars and embedded parts.
3) When using a plate vibrator:
1) Under normal circumstances, the continuous vibration of the plate vibrator at one point should be subject to the uniform slurry on the surface of the concrete. When moving the vibrator, it should be vibrated in a row, and the front and rear positions and rows should be 100mm between each other to prevent leakage.
2) The effective depth of action of the plate vibrator in the unreinforced and single-rib plate is 200mm;It is about 120mm in a double-reinforced slab.
3) When the concrete surface is tilted by vibration, it should be gradually moved from low to high to ensure that the vibration is compact.
6.Curing of concrete.
The beam and plate span of this project is large, the area is large, in order to ensure that the concrete that has been poured in the specified age to achieve the strength of the design requirements, to control the concrete to produce shrinkage cracks, must do a good job in the maintenance of concrete.
1) The curing time of ordinary concrete is not less than 7d, and the curing time of micro-expanded concrete is not less than 14d.
2) Set up a special maintenance team, 24 hours on duty.
3) The foundation cushion cap and horizontal beam plate are covered with sacks for sprinkling and curing, and should be carried out about 12h after the concrete is poured, and the number of watering should be decided according to the state that can ensure that the concrete is in a wet state.
4) For vertical components such as walls and columns, spray curing liquid is used for maintenance.
7.Quality control of concrete construction.
Concrete test block indwelling:
1) Retention of compressive test block: each construction layer of each construction section, the sampling of concrete of different grades shall not be less than a group of compressive test blocks every 100m3 (including less than 100m3), and an appropriate amount of test blocks under the same conditions shall be left.
2) The retention of impermeability test blocks: two groups of impermeability test blocks should be left for every 500m3 poured, and two groups should be left for every additional 250 500m3. One group is kept as standard, and the other group is maintained under the same conditions.
3) Each beam and plate pouring platform is left with two sets of test blocks, and the pressure test is carried out after the age of 7 days and 10 days, which is used as the basis for dismantling the beam plate formwork.
The quality inspection standards for concrete are shown in the table below
Table 66-1 List of quality inspection standards for concrete works.
1.The construction joint is left in place.
The concrete structure can not be continuously poured during the construction, according to the construction specification, the construction organization and the design requirements of the facility joint, the construction joint is located in the structure shear force is less and convenient for the construction of the part: the horizontal construction joint of the column is left in the cushion cap part, and the floor is left at the place where it is 10mm lower than the bottom of the beam and at the top surface of the floor slab;The wall is left in the range of 1 3 in the lintel span of the door and window openings. The floor slab with the main and secondary beams should be poured along the direction of the secondary beam, and the construction joint is left in the range of 1 3 in the secondary beam span, the plate is left in the 1 3 places of the plate span, and the construction joint of the staircase is left in the part of 1 3 of the staircase. 2.Construction joint construction methods and measures.
When the concrete floor and the side wall are poured concrete, the horizontal construction joint is left on the side wall that is 500mm away from the bottom plate surface, and the 3mm thick waterproof steel plate 300mm wide is adopted at the horizontal joint during construction, and the surrounding is evenly and vertically placed and fixed around the 500mm high place on the upper surface of the reverse beam, and the groove is outward, and the concrete joint of two pourings is 150mm wide respectively.
The position and size of all horizontal construction joints of this project refer to the construction joints after chiseling and forming, and the construction joints reserved in the concrete pouring process should be 10mm higher than the construction joints after forming. All vertical, horizontal direction of the construction joint in the joint before the joint should be used elastic control line, marble machine grooving, manual chiseling mode, before the next process, the construction joint position should be chiseled and cleaned up, to ensure that the joint position of the concrete is dense, the line mouth is straight and smooth, so that the stubble part of the concrete joint tight, straight, beautiful.
In the construction joint part of the wall (column) and the floor (beam) junction, first 20mm up the control line at the bottom of the plate (beam), and then use a marble machine to cut a 5mm deep incision along the control line, and then use the method of manual chiseling from both sides of the wall (column) to remove the construction joint part of the chiseling, remove the slurry, expose the stone to the bottom of the plate (beam) 20mm, the incision part should be smooth and straight, and the height difference should be controlled within 2mm.
When pouring concrete, first use the same mix ratio of the stone mortar to pour the concrete, vibrating must be meticulous and rigorous, to ensure that the joint is dense.
In order to ensure that the poured concrete reaches the strength required by the design within the specified age period, and to prevent the concrete from shrinking cracks, the maintenance of the concrete must be done.
1) Covering watering and curing should be carried out within 12h after the concrete is poured. The number of watering should be determined according to the state that can ensure that the concrete is wet.
2) Concrete curing of each component.
1) Wall maintenance.
The walls are maintained by manual watering.
2) Frame column maintenance.
After the mold is removed, the frame column is wrapped with plastic wrap in time, and a special person is arranged to water and moisten, and special attention is paid to the maintenance of the column head.
3) Maintenance of bottom plate and beam plate.
After pouring concrete and final setting, the surface of the bottom plate is covered with straw bags and plastic film for water storage and curing, and the beams and slabs are covered with water-retaining plastic film for watering and curing. The concrete curing time for the basement with impermeability requirements is not less than 14d;The curing time for ordinary concrete is not less than 7d.