Pumping concrete construction method

(A) concrete supply:
1, commodity concrete: the proposed adoption of ISO9002 quality certification of the manufacturer, according to the actual situation of the production technology monitoring requirements are as follows:
(1) Material requirements:
A, bulk cement:
a. Portland 325 or above selected ordinary Portland cement or Portland cement.
b. When cement enters the factory, there should be a factory certificate or test report, and check its varieties, marking the date of manufacture. If found to be damp or expired before use, the sample should be resampled.
c. Quality indicators in the cement quality indicators should be consistent with the provisions of the standard. Quality indicators include magnesium oxide content, sulfur trioxide content, loss on ignition, fineness, setting time, stability, compressive strength and flexural strength.
d. The maximum amount of concrete cement should not be greater than 550kg / m3.
B, sand:
a. Sand is the first choice of high-quality sand river terminal in Shenzhen.
b. Concrete projects should be selected coarse sand. For pumping concrete, sand should be used in sand, sand rate should be controlled at 40 ~ 50%.
c. Sand content (by weight), not more than 3% when the concrete strength level is higher than or equal to C30, not more than 5% below C30, for impermeability, frost resistance or other special requirements Of concrete sand, the clay content should not exceed 3% of C10 or C10 below the concrete sand, the mud content may be relaxed as appropriate.
C, gravel (gravel or pebble)
a. Stone should use granite as well.
b. The maximum size of the stones shall not be greater than 1/4 of the cross-sectional dimension of the structure and not more than 3/4 of the minimum clearance between the bars. Concrete aggregate aggregate maximum size should not exceed the thickness of the plate 1/2. And shall not exceed 60mm. For pumping concrete, the ratio of the maximum particle size of gravel to the inner diameter of the pipe should be less than or equal to 1: 3 and pebbles should be less than or equal to 1: 2.5.
c. The amount of clay in gravel (by weight) is not more than 1% for concrete equal to or higher than that of C30; not more than 2% for materials less than C30; for mixtures with resistance to freezing, impermeability or other special requirements Condensation, gravel content of not more than 1%; for C10 or C10 below the concrete, gravel content of mud can be relaxed as appropriate.
d. The content of the medium needles and flaky particles in gravel (by weight), not more than 15% when the concrete strength level is higher or lower than C30; not more than 25% lower than C30; Can be relaxed to 40%.
D, water: drinking water in line with national standards can be mixed all kinds of concrete, do not need to be tested.
(2) Operating conditions:
a. The task list must include the name, location, location and quantity of the project, technical requirements for concrete (strength grade, retarding and special requirements), on-site construction methods, production efficiency (or duration), handover Then the requirements, as well as coordination between supply and demand, together with the notice of construction mix issued.
b. The equipment is running normally and the number of concrete transport vehicles meets the requirements.
c. adequate supply of materials, in particular the designated cement varieties have sufficient reserves or follow-up supply guarantee.
d. All materials should be tested and qualified to meet the requirements.
e. mixing station, pouring pounding site and transport vehicles have a reliable means of communication between.
(3) The quality inspection of commercial concrete requirements:
a. Concrete pumping, with more than 100m3 of work per class, should be dispatched by quality inspectors.
b. Concrete mixer truck out of the station, each car must be checked by the quality inspector and transmissibility of visa compliance. Slump Sampling once per car; concrete truckload check each mix of not less than once a day.
c. When sampling on site, the concrete should be represented by 1/4 to 3/4 after discharging the mixer. Concrete sampling, specimen production, conservation, both parties should be both signed by the supply and demand approval.
d. Mixing truck shall not appear before discharge and initial setting phenomenon.
2, self-mixing concrete production: Self-mixing concrete used to prevent the temporary provision of commercial concrete emergency measures and sporadic concrete on-site mixing, raw materials and mix should be consistent with the commodity concrete.
(1) According to the ratio of each plate (slot) the amount of various materials to be said.
(2) loading order: general first installed gravel, then install the cement, and finally loaded sand, if you need to add admixture, it should be added together with the cement.
(3) The minimum time for concrete mixing is determined according to the requirements of the construction specification. When admixture is added, the mixing time should be extended appropriately. Fly ash concrete mixing time than the reference mixed soil to extend 10 to 30s.
3, concrete transport:
(1) Concrete In the field of transport vehicles trolleys, bucket, chute (basement -), pumping and so on.
(2) After the concrete is discharged from the mixer, it should be promptly transported to the place of pouring for the duration, which can not exceed the initial setting time. In the transport process, to prevent concrete segregation, loss of cement slurry, slump changes and the phenomenon of initial setting. If the concrete is transported to the place of pouring, there must be the second mixing before watering on the scene of segregation.
(3) Concrete transport roads should be smooth and smooth, if uneven, should be paved bridge æž‹. In the construction of the floor, it should be laid a special bridge is prohibited bar stamped personnel and staff.
(B) pumping concrete:
1, pumping process:
(1) Before pumping concrete, first pump the clear water in the hopper out of the pipe to wet and clean the pipe. Then, add cement mortar (or 1: 2 cement mortar) with the same proportion of concrete to the hopper, lubricate After the pipeline can start pumping concrete.
(2) When starting to pump, the pumping speed should be slowed down. The change of hydraulic pressure should be within the allowable range. When the pumping is smooth, it should be pumped with normal speed.
(3) During pumping, the amount of concrete in the hopper should be maintained at a minimum of 10 mm above the cylinder bore to 150 mm below the hopper mouth. Avoid inefficient inhalation, easy inhalation of air caused by the tube, too much when the counter will overflow and increase the shaft load.
(4) Concrete pumping should be continuous operation, when the concrete supply is not timely, to reduce the pumping speed, pumping temporarily suspended, stirring should not stop. When the leaves are stuck, the need to reverse queuing, and then forward, reverse a certain period of time, to be smooth before continuing to pump.
(5) if the pumping midway stop time more than 20min, the pipeline is longer, the pump should be open every 5min, pumping a small amount of concrete, the pipeline is shorter, you can use positive and negative every 5min trip 2-3, Make the concrete creep in the pipe to prevent segregation of bleeding water, long time to stop pump (more than 45min), high temperature, concrete slump hours may cause plug pipe, concrete should be removed from the pump and pipe.
(6) pumping away after the recent pouring gradually demolition.
(7) pumping in the hot season, should be covered with warm grass bag pipe cooling to reduce the mold temperature.
(8) The sum of the horizontal conversion distances of the pumping pipes shall be less than the maximum pumping distance of the equipment.
2, the end of pumping cleaning work:
(1) At the end of pumping, the amount of concrete stored in the concrete pipe and in the hopper and the amount of concrete left to be poured (1.75 m³ per 100 mm diameter pipe) should be estimated in order to determine the amount of concrete to be mixed.
(2) When the pumping is completed, the air compressor is used to clean the ball when cleaning the pipeline. Put a good special wash water, then start the air compressor, progressive pressure. During cleaning, the pipe should be tapped at any time to see if the concrete is close to emptying. When there is about 10m of concrete in the delivery pipe, the compressor should be slowly depressurized to prevent large explosion and injury.
(3) After the pump is finished, the concrete pump, distributor and pipe should be cleaned immediately. After the pipe is disassembled, the pipes should be stacked according to different specifications.
(C) concrete pouring:
1, before pouring concrete preparation:
(1) Organizing the construction team to make technical explanations, the team must be familiar with the drawings and specifying the various technical factors (concrete strength grade, impermeability grade, initial setting time, etc.) of the construction site.
(2) Organizing the team to hand over the rebar and template, if there is no concrete construction condition, the concrete construction can not be carried out.
(3) Organization of construction equipment, tools and other supplies, to ensure good.
(4) before pouring wetting template should be wet, wall, column template cleaning port should be cleared of debris and water and then closed.
2, the general requirements of concrete pouring:
(1) The free fall height of concrete falling from the bucket mouth shall not exceed 2m, if more than 2m, measures must be taken. Straps, tubes, chutes, or door shutters should be used on the sides of the formwork (raw mouth).
(2) Pouring concrete should be segmented layering, pouring height of each layer should be based on structural features, steel density decision. General layered height of the role of plug-in vibrator part of the length of 1.25 times the maximum not exceeding 500mm. The thickness of the slab vibrator is 200 mm.
(3) Start the vibrating rod, vibrate the hand grip the flexible hose at the top of the vibrating rod and quickly insert the interior of the concrete. When vibrating, the vibrating rod is slightly twitched up and down, vibrating for 20-30 seconds, Re-emergence of bubbles, no significant sinking, the surface of the slurry and surface formation level prevail. The use of plug-in vibrators should be inserted quickly inserted slow, plug points should be evenly arranged, point by point movement, in order, shall not be omitted, so that even solid. The moving distance is not more than 1.5 times the radius of vibration rod (usually 300 ~ 400mm), the distance from the template should not be less than 200mm. Vibrate the upper layer should be inserted into the lower concrete surface 50 ~ 100mm, in order to eliminate the seam between the two layers. The spacing of the plate vibrators should be such that the plate of the vibrator covers the edges of the tapped part.
(4) pouring concrete should be carried out continuously. If it must be intermittent, its intermittent time should be shortened, and should be in the first layer of concrete before the initial setting, the second floor of concrete pouring completed. Intermittent maximum time should be determined according to all types of concrete and concrete initial setting conditions, generally more than 2 hours should be handled by construction joints.
(5) Concrete pouring should be sent to observe the regular template steel reinforcement, reserved holes, embedded parts, such as whether there is displacement deformation or plug tendons, and found that the problem should be immediately irrigated and concrete pouring has been completed before the initial setting .
(6) pouring finished, check the reinforced surface is concrete pollution, and timely scrub clean.
3, wall concrete pouring:
(1) The cement mortar with the same proportion of 50mm concrete as the concrete shall be uniformly poured on the bottom before the wall is poured or the newly-fired concrete is mixed with the lower concrete. Mortar application shovel into the mold, do not use the hopper directly into the mold.
(2) Wall concrete should be layered and vibrated, each pouring thickness control in about 500mm. Concrete cutting point should be scattered layout, recycling, continuous.
(3) pouring wall hole, make the hole on both sides of the concrete height roughly the same. Vibration concrete to be even and dense, especially the wall thickness is small, the door and window structure reinforced with interlocking bars more dense parts should be Φ25 vibration rod, the other wall parts Φ50 vibration rod, taking into account the wall under the wall window After the concrete sealing mold can not be directly vibrated, you can leave the mouth of the window in advance to stay alive until the concrete pouring to the location and vibrate and then seal the mold and reinforcement. When vibrating, the vibrating rod should be 300mm above the edge of the hole and vibrate simultaneously from both sides to prevent deformation of the hole. Large holes in the lower part of the template should be opened and added vibration.
(4) The structural column concrete should be layered pouring, the thickness of each layer shall not exceed 300mm.

(5) construction joints set: wall should be located in the door and window openings in the mid-1/3 range. Vertical joints in other parts of the wall should be set aside by the construction plan. Column horizontal seam left below the main beam.
4, beams, slabs concrete pouring:
(1) Beams of ribbed floors shall be poured at the same time. The pouring method shall be started from one end by the "Kneading Method". The beams shall be first placed into a staircase in layers and then poured into the concrete together with the slabs when the floor is reached.
(2) The thickness of the floor pouring virtual shop should be slightly larger than the thickness of the plate with a vertical vibrator pouring direction to vibrate. Constant use of moving signs to control the thickness of concrete slab. Vibration is completed, with a scraper or planing surface smooth.
(3) When pouring beams and slabs integral with columns and walls, they should be suspended for 1-1.5 hours after the pillars and walls have been poured, so as to obtain a preliminary solidity before continuing the pouring.
(4) Construction joints should be laid along the direction of the secondary beam, the construction joints should be kept within 1/3 of the secondary beam span. The construction joint surface should be perpendicular to the secondary beam axis or plate surface. The unidirectional slab construction joints are left in any position parallel to the short side of the plate.
(5) construction joints with wood, steel wire block.
(6) Construction joints are subject to the compressive strength of concrete that has been poured to not less than 1.2Ppa, to allow continued pouring.
(7) Before pouring the concrete at the construction joint, the surface of the concrete joint should be chiselled, the turquoise stones should be removed and rinsed with water. After removing the stagnant water, first pour a layer of cement or cement mortar with the same ratio of concrete, and then continue pouring concrete.
(8) Before pouring the beam wall joint, it should be handled by the construction joint of the wall.
5, staircase concrete pouring:
(1) Stairway concrete pouring from bottom to top. The first concrete floor compaction, to reach the step position and stepping concrete pouring, continuous continuous upward push, and at any time with a wooden trowel will step the smooth surface.
(2) staircase concrete pouring should be completed.
(3) Construction joints Location: According to the structure of the situation can be set aside in the staircase plate span or staircase 1/3 range.
6, pouring concrete slab, the concrete wall node area by high-intensity concrete construction, the interface at the wall column edge 500.
(D) the conservation of concrete:
1, concrete pouring is completed, it should be covered within 12 hours, and water conservation.
2, concrete water conservation date, admixture retarding admixture or concrete with anti-seepage requirements shall not be less than 14 days. Before the concrete strength reaches 1.2Mpa, it shall not be stepped on or vibrated on it. Column, wall mold conservation more than 2 days, remove the mold and then continue to water conservation.
3, the number of daily watering should be able to keep the concrete in a state of adequate wetting. Pour twice daily at room temperature.
4, large-scale structures such as floor, floor, roof and other water conservation, storage tank a class of engineering, can be removed within the template, until the concrete reaches a certain intensity after water conservation.
5, Sun care agent can be sprayed, forming a protective film on the concrete surface, to prevent water evaporation, to achieve the purpose of conservation.
6, when covered with plastic film, the surrounding pressure should be tight and should keep the film has condensed water.

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