1 control points before construction of aluminum alloy formwork
1. Review the special construction scheme of aluminum alloy formwork, and provide effective construction basis in line with the characteristics of this project for subsequent construction.
2. The processed aluminum alloy template shall be inspected and pre-assembled for acceptance.
3. Supervise the construction unit to make technical disclosure to the aluminum alloy formwork installation personnel.
4. Supervise and urge the construction unit to disclose the cooperation nodes of cross-work between different types of work.
5. When the aluminum alloy formwork on the first floor of each building is installed for the first time, the manufacturer's technicians and project technicians are required to give on-site technical guidance to the operators.
2 aluminum alloy template installation process control points
Wall column formwork installation
1. Brush the release agent
Upload and place the dismantled and cleaned templates in the lower layer according to the region and order. Overlapping pile, should make the board face up, easy to besmear brushs release agent, and then piece by piece besmear brushs release agent, in order to avoid the subsequent concrete is poured concrete die-sticking phenomenon.
2. Temporary fixation of interior wall formwork
Interior wall formwork shall be installed from the internal corner (corner) and extended to both sides according to the template number sequence. In order to prevent the formwork from falling down, temporarily fix the support (wood square, steel pipe, etc.). ) and on each template besmear brushs the right amount of release agent.
pin
Generally, every 300mm, nail 1 pin on the vertical formwork. Don't push too hard when nailing, and there should be no gaps at the joint of the template. Bolts at the end of transverse splicing formwork must be nailed firmly, with holes left in the middle and inserted from top to bottom to avoid falling off when vibrating concrete.
4. Side wall formwork installation
When installing the formwork of the other side wall, vertically place the internal bracing steel bar with the same size on the shear wall steel bar near the hole of the pull tab, and check whether the pull tab is blocked by the steel bar (especially the lower part of the wall and column). If it is blocked, move the steel bar slightly with tools to ensure that the PVC conduit can pass smoothly. The hole position of the template pull-tab on both sides must be right, which is also one of the methods to check whether the wallboard is installed correctly.
5. Adjust verticality
Before each wall template is closed, the templates on both sides should be adjusted to stand vertically on the control line to ensure the smooth progress of the next process.
6. Back stare blankly installation
Back stare blankly installation should be bottom-up, first external wall and then internal wall. The limit reinforcement of back stare blankly at the external angle should be close to the inner edge of the template, and the back stare blankly at the internal angle should be installed first, and then the external angle should be installed. The installation of the external angle must be tightened horizontally. Every time a back stare blankly is installed, an iron sheet and a herringbone nut must be installed. The iron sheet is vertically buckled on the back stare blankly, and then the herringbone nut is tightened. The exposed screw protection wire of herringbone nut should be ≥ 50 mm.
Opposite pulling screws shall be installed at the position of wall sealing plate; The distance between the opposite screw and both ends of the back stare blankly should be consistent. After the installation of the back beams on both sides is completed, the gables nuts will be reinforced again, and two people will cooperate with the construction on both sides of the wall at the same time.
7. Installation of diagonal braces
(1) diagonal braces should be installed on both sides of column and wall formwork, and the horse stool made of embedded φ 14 steel bars should be used as the stress point of diagonal brace foundation support, and the diagonal brace spacing should not be greater than 2000 mm
No less than two sets of diagonal braces shall be set for walls with a width of ≥2000mm, and no less than one set of diagonal braces shall be set for walls with a width of < 2000mm or short-leg shear walls, and the diagonal braces on both sides shall be 300mm away from the sealing plate.
Each group of diagonal braces consists of long-side members, short-side members and fixed codes. The distance between the yard and the wall should be fixed so that the angle of the long side of the diagonal brace is 45 -55 degrees, and the angle of the right side of the diagonal brace is 10-15 degrees (see figure 1).
Figure 1
(2) For external walls and other parts where diagonal braces can only be installed on one side, the diagonal braces on the same side should be tightened by chains to form a two-way constraint.
8. Wall column template adjustment
Align the 1m elevation control line with laser levels, and observe whether the laser line coincides with the wall control point and whether the wall coincides with the wall positioning line, and adjust if there is any error.
Insert the hammer rod into the top back stare blankly, and the hammer is about 50mm vertically from the ground to stabilize the hammer; Measure the vertical distance between the wall and the messenger wire with a tape measure. Take at least three points on the same vertical plane, and the distance between points on the same wall is 500mm.
Re-check the verticality of the wall with the lowest point as the benchmark. If there is any error, adjust it in time.
Beam formwork installation
1. Nail the cleaned beam bottom plate (B), early dismantling head (BP) and internal corner template (LSA, internal corner template connecting beam and wall) in the correct position with bolts. Special attention should be paid to the support of early dismantling head, which must be on the same vertical center line with the bottom support of lower beam to ensure the safety of concrete structure.
2. When installing the beam bottom plate, two people cooperate, one person at one end holds both ends of the beam bottom plate, stands on the operating platform, and bolts are used to connect the internal corner formwork (LS) with the wallboard at the specified position.
If the beam bottom is too long, two people should install the beam bottom and another person should install the beam bottom support, so as to avoid the template at the beam bottom from being overweight and sinking, which will lead to premature deformation of the template and affect the operation safety.
3. After the beam bottom is leveled with support, the beam side formwork can be installed, and all horizontally connected formwork and bolts must be inserted from top to bottom, so as to avoid the bolts falling off when pouring concrete and vibrating, causing formwork explosion and affecting safety.
Installation of roof formwork
1. After installing the internal angle template at the top of the wall beam, install the floor keel, then install the roof according to the trial assembly number diagram, and assemble the standard plate template in turn until all the aluminum templates are assembled. The support rod under the early dismounting head of the floor keel should be vertical without looseness.
2. After the installation of each bay roof is completed, it is necessary to adjust the support bar to a suitable position to make the board surface smooth. For roofs with a span of more than 4m, the formwork shall be arched according to the design requirements. Unless otherwise specified, the springing height of aluminum alloy formwork is generally11000.
Installation of peripheral guide wall plate (K plate) and balcony line
1. In the parts with continuous formwork, such as elevator shaft and external wall. The floor is enclosed in a closed circle with guide wallboard as the connecting member of the upper formwork.
2. After the first layer of concrete pouring is completed, the second layer of guide wall panel must be installed, one layer is used to be fixed on the upper layer of formwork that has not been dismantled, and the other layer is used to be fixed on the upper part of the wall formwork around the floor.
After pouring concrete, keep the upper guide wallboard as the starting point of the lower wall formwork. Connection between guide wall plate and wall formwork: Before installing guide wall plate, make sure that the cleaning and oiling work has been completed.
In order to prevent the pin from falling off during pouring, the pin must be inserted downward from the lower frame of the wall formwork to the upper frame of the guide wallboard. There is a 26mm× 16.5mm long hole on the guide wall plate. Before pouring, install M 16 bolts near the tank bottom, which will be anchored in the solidified concrete.
After pouring is completed, the bolts can be adjusted to adjust the levelness of the guide wall plate when necessary to control the verticality of the formwork.
3. After the installation of aluminum formwork, the beam-slab pipeline shall be embedded. After the reserved pipeline position of the beam is determined, the hole should be opened in a fixed position and cannot be moved again; The reserved plate shall be fixed with aluminum formwork with screw holes.
Quality requirements for installation of aluminum alloy formwork
1. Template axis positioning, overall dimensions and horizontal elevation are accurate.
2. The board should be flat and clean, flat-fell seam tightly, no leakage.
3. It has sufficient bearing capacity, rigidity and stability, and can bear the dead weight, lateral pressure and construction load of newly poured concrete.
4. Template installation deviation should be controlled within the scope permitted by the specification.
5. The angle of Yin and Yang should be straight and square, with neat edges and corners without dislocation, inclination and concave-convex lines.
6. The beam-slab support system is equipped with an adjustable base at the bottom and an adjustable support head at the top to adjust the elevation and level of the formwork.
3 Inspection points before issuing concrete pouring and tamping orders
All templates should be clean and coated with qualified release agent.
Ensure that the wall formwork is installed according to the lofting line.
Check whether all openings are correct in size and deformed.
Check whether all horizontal molds (top mold and beam bottom mold) are horizontal.
Ensure that the support rods at the bottom of the slab and the bottom of the beam are vertical, and the support rods are not loose in the vertical direction.
Check whether the back stare blankly and brace of wall formwork and column formwork are correct.
Check whether the traction screws, pins and wedges are kept in place and secure.
Remove the remaining materials and other objects from the pouring area.
Ensure that the support frame for suspending the working platform is reliably fixed on the concrete structure.
4 Cause analysis and preventive measures
Figure 2: Expansion mold for elevator shaft wall
All templates should be clean and coated with qualified release agent.
cause analysis
(1) connectors are not set as required, resulting in poor integrity of the formwork.
(2) The wall template has no pull-tab or the pull-tab spacing is too large and the specification is too small.
(3) The internal formwork support is not firm, and it is easy to squeeze the formwork when the concrete is vibrated.
(4) The spacing between the wall column formwork fixtures is too large, or the formwork is not clamped.
(5) The concrete pouring speed of the wall column is too fast, the pouring height at one time is too high, and the vibration is too large.
Preventive and control measures
(1) Support spacing should be able to ensure no deformation under concrete weight and construction live load.
(2) The upper part of the wall should have a temporary supporting head to ensure the width of the hole in the wall when the concrete is cast.
(3) When pouring concrete, the materials should be evenly and symmetrically cut, and the pouring height should be strictly controlled, especially on both sides of the door and window formwork, so as to ensure the compactness of concrete and prevent the formwork from being deformed due to excessive vibration.
Phenomenon 2: After the concrete of beams and walls is poured, slurry leakage occurs, and honeycomb and pits appear on the concrete surface (see Figure 3 and Figure 4).
Fig. 3: concrete honeycomb at the bottom of beam Fig. 4: concrete honeycomb and pits on the wall.
cause analysis
(1) Improper use of template release agent.
(2) Template flat-fell seam control is not in place.
(3) The contact mounting surface may be deformed.
Preventive and control measures
(1) According to the actual quality defects in site construction, the technicians of aluminum mold manufacturers are invited to provide on-site technical guidance, and the types of release agents are adjusted according to the actual situation. The vertical formwork adopts oily release agent, and the horizontal formwork adopts water-based release agent.
(2) Strictly control the sealing measures between templates, and do not use linoleum, plastic sheets, cement bags, etc.
(3) Beam-column joints should be firm, flat-fell seam should be tight, and dislocation should be corrected.
Phenomenon 3: The external angle of the wall column member is seriously damaged (see Figure 5 and Figure 6).
Fig. 5: damage to external corners of walls and columns Fig. 6: damage to external corners of walls and columns.
cause analysis
(1) The template was not cleaned and the surface was covered with cement slurry.
(2) The form removal time is too early or the seesaw is stressed.
Preventive and control measures
(1) cement slurry on the surface of aluminum alloy formwork shall be cleaned.
(2) After the strength of concrete meets the design requirements, the formwork shall be removed, and the removal process shall be controlled to avoid damage to concrete members caused by excessive force.
Phenomenon 4: The root of the wall column is leaking and rotten (see Figure 7).
Figure 7: Rotten roots at the foot of the column
cause analysis
(1) The concrete surface at the root of the wall column is uneven, and there is a gap between the bottom of the formwork and the concrete surface, which leads to root rot due to slurry leakage during concrete pouring.
(2) The high-low span is misaligned with the upper and lower layers of the external wall and column, resulting in slurry leakage and rotten roots of the hanging feet.
(3) the wall column template root slurry leakage caused by column root.
(4) The garbage and accumulated water at the root of the wall column formwork are not cleaned and leveled, resulting in slag inclusion and rotten roots.
(5) Improper vibrating operation, slurry leakage, insufficient vibrating, excessive vibration, or one-time pouring is too high, and the bottom vibrating is not in place, resulting in rotten roots.
(6) Improper concrete gradation, too large or too small water cement ratio causes root rot.
Preventive and control measures
(1) A cleaning port is left at the bottom of the template. Before pouring concrete, remove the garbage and water. Then, plug the cleaning mouth and pour concrete.
(2) Training vibrating hands, making technical disclosure and mastering vibrating time. Concrete pouring of wall column should be carried out in layers along the height.
(3) Check and control the slump of concrete in time, and the slump should be within 150mm.
5 concluding remarks
To sum up, the aluminum alloy formwork support system can ensure the section size, surface flatness and verticality of concrete members during construction and use.
However, pre-control is needed in the process of construction and supervision, and the quality control of pre-assembly, installation and removal of aluminum alloy formwork is more detailed and demanding, so as to ensure that the advantages of high efficiency and high quality of aluminum alloy formwork are reflected.
I believe that after the above introduction, everyone has a certain understanding of what to do if the slurry leakage is wrong in the construction of aluminum alloy formwork. Welcome to Zhong Da for more information.
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