Construction method of a roof panel under post-cast wall and air duct plate

Abstract

This invention discloses a construction method for post-cast walls and duct slabs under roof panels, comprising: erecting a roof panel support system to separate the roof panel pouring area from the wall area; tying the roof panel reinforcement and wall reinforcement, and pre-embedding several fiber cement sleeves; pouring concrete in the roof panel area and curing it; installing wall formwork and duct slab formwork on the outside of the wall reinforcement; setting an overflow trough on the top of the wall formwork; conveying concrete in layers through the fiber cement sleeves; air and excess concrete in the pouring cavity forming an overflow fluid; cutting off the overflow fluid, leveling the cut surface and continuing curing; removing the wall formwork, duct slab formwork and support frame, cutting off the portion of the fiber cement sleeves that exceeds the preset height of the roof panel, and trimming the cut. This invention solves the problems of high-altitude formwork difficulty, limited concrete delivery and vibration, difficulty in observing the pouring status, poor ventilation at the top of the wall, and difficulty in guaranteeing the forming quality of the wall and duct slab in existing construction methods.

Description

Technical Field

[0001] This invention relates to the field of concrete construction technology for building main structures, specifically to a construction method for post-cast walls and ventilation duct slabs under roof panels. Background Technology

[0002] In the construction of industrial and public buildings, concrete walls and ventilation ducts are often installed beneath the roof slab. These structures are usually located at a high position, with limited construction space between the walls and the roof slab. In addition, the interlacing arrangement of the wall reinforcement, roof reinforcement, and ventilation duct reinforcement significantly restricts formwork installation, concrete delivery, and vibration operations.

[0003] In current construction practices, one method involves simultaneously erecting formwork and pouring concrete for the roof slab, walls, and ventilation duct slabs as a single, integral structure. This method requires constructing a tall support system covering the roof slab and lower walls in a single setup, resulting in significant loads on the formwork and supports, and numerous overlapping operations at heights. Due to the dense reinforcement at the top of the walls, the concrete delivery channels are relatively narrow, making it difficult for pump pipes and vibrating equipment to penetrate the walls. Furthermore, it is difficult for construction workers to directly observe the concrete filling within the formwork cavity. Especially at the top of the walls and at the junction of the walls and ventilation duct slabs, air is difficult to expel, easily leading to problems such as insufficient concrete filling, honeycombing, voids, or localized inadequate compaction.

[0004] Another approach is to construct the lower walls and duct slabs first, followed by pouring the roof slab. While this method reduces the organizational difficulty of simultaneously constructing the roof slab and walls, it creates construction joints between the walls, duct slabs, and the subsequently poured roof slab. If these construction joints are not properly treated, cracks or water seepage can easily occur at the junction of the roof and walls. Furthermore, when the duct slabs are supported by separate formwork, their elevation, thickness, and cross-sectional dimensions are difficult to control, and grout leakage, formwork bulging, or localized deformation may occur during the pouring process.

[0005] For post-cast construction of walls beneath the roof slab, the current practice typically involves setting up a feed inlet on the formwork, and additionally adding a vibration inlet or observation port as needed. Multiple openings not only increase the workload of formwork fabrication and sealing but also easily become points of grout leakage. When the top of the wall lacks effective ventilation and overflow channels, as the concrete gradually rises, the air trapped at the top of the formwork is difficult to expel in time, and it is also difficult to determine whether the concrete has filled the wall completely. After demolding, the top of the wall often needs to be chiseled and repaired.

[0006] Therefore, the existing construction methods still cannot simultaneously ensure the early closure of the roof, the safety of high-altitude formwork, the smooth pouring of concrete for the walls and duct slabs, sufficient vibration, and dense top formation. It is necessary to further improve the construction methods for the post-cast walls and duct slabs under the roof slabs. Summary of the Invention

[0007] The purpose of this invention is to provide a construction method for post-cast walls and ventilation duct slabs under roof panels, in order to solve the problems of high-altitude formwork difficulty, limited concrete feeding and vibration, difficulty in observing the pouring status, poor ventilation at the top of the wall, and difficulty in ensuring the forming quality of the wall and ventilation duct slab in the existing construction methods.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A construction method for post-cast walls and ventilation duct slabs under roof slabs includes the following steps: S1: Erect the roof panel support system and lay the bottom formwork. Set up a wire mesh template in the vertical projection area of ​​the wall to be poured to separate the roof panel pouring area from the wall area below. Tie the roof panel reinforcement and wall reinforcement, and embed several fiber cement sleeves at intervals along the length of the wall. The fiber cement sleeves pass through the roof panel pouring area, and their lower ends pass through the wire mesh template and connect with the wall area. The upper ends are higher than the preset height of the roof panel. S2: Pour concrete in the roof slab area and cure it to form a rigid superstructure; S3: Install wall formwork on the outside of the wall reinforcement, erect a duct plate support frame and install duct plate formwork. The wall formwork and duct plate formwork enclose each other to form a wall pouring cavity and a duct plate pouring cavity that are interconnected. Set an overflow trough for the wall formwork on the top of the wall formwork and connect it with the wall pouring cavity. S4: Concrete is delivered in layers to the wall pouring cavity and the air duct plate pouring cavity through the fiber cement sleeve. The vibrating equipment is inserted into the wall pouring cavity through the fiber cement sleeve to vibrate in layers, and the concrete filling status is observed through the fiber cement sleeve. Air and excess concrete in the pouring cavity are discharged through the wall formwork overflow channel and form an overflow on its outside. S5: After the concrete of the wall and duct slab reaches the strength required for the cutting operation, cut off the overflow along the designed outline of the wall, level the cut surface and continue to cure until the demolding strength is reached; remove the wall formwork, duct slab formwork and support frame, cut off the part of the fiber cement sleeve that is higher than the preset height of the roof panel, and trim the cut.

[0009] To optimize the above technical solution, the specific limitations also include: The wire mesh template is arranged along the length of the wall to be poured and fixed to the underside of the roof slab reinforcement; the wire mesh template is made of galvanized steel wire mesh with a mesh size of 4-6mm.

[0010] Preferably, the fiber cement sleeve has an inner diameter of 180-220mm and a wall thickness of 15-25mm, with its upper end extending 200-300mm above the pre-set height of the roof panel, and the spacing between adjacent fiber cement sleeves along the length of the wall to be poured is 1.5-2.0m.

[0011] Preferably, before pouring concrete in the roof panel area, a removable sealing device is installed at the upper end of each fiber cement sleeve to seal the fiber cement sleeve; before conveying concrete through the fiber cement sleeve to the wall pouring cavity and the air duct plate pouring cavity, the removable sealing device is removed.

[0012] Preferably, the overflow groove of the wall template has a groove height of 100-150mm and a width of 150-200mm, and the spacing between adjacent overflow grooves of the wall template along the length of the wall to be poured is 1.5-2.0m.

[0013] Furthermore, the fiber cement sleeves and wall formwork overflow channels are arranged in segments along the length of the wall to be poured, with each fiber cement sleeve corresponding to a wall formwork overflow channel, and the wall formwork overflow channel is located below the corresponding fiber cement sleeve.

[0014] Preferably, in step S4, the concrete in the wall pouring cavity and the air duct plate pouring cavity is poured in layers, with each layer of concrete having a pouring height of 400-1000mm. After each layer of concrete is poured and fully vibrated, the next layer of concrete is poured.

[0015] Furthermore, in step S4, concrete is transported using a concrete delivery pump pipe. The concrete delivery pump pipe and the vibration equipment are used in conjunction with the same fiber cement sleeve at different construction periods. The fiber cement sleeve serves as the concrete discharge channel, the vibration channel, and the concrete filling status observation channel in sequence.

[0016] Furthermore, the roof panel support system includes supporting steel beams, steel brackets, roof panel support frames, and wall ties; the steel brackets are fixed to the cast-in-place wall via pre-embedded cones; one end of the supporting steel beam is fixed to the reference surface at the bottom of the structure, and the other end is supported on the steel bracket; the roof panel support frame is erected on the supporting steel beam and is connected and fixed to the cast-in-place wall via a wall tie.

[0017] Preferably, in step S5, after cutting off the portion of the fiber cement sleeve that extends above the preset height of the roof panel, the upper end cavity of the fiber cement sleeve is sealed with micro-expansion waterproof mortar, and a waterproof sealing layer is set at the junction of the fiber cement sleeve and the roof panel concrete.

[0018] Compared with the prior art, the beneficial effects of the present invention are: The construction method for post-cast walls and duct slabs under roof panels provided by this invention involves pouring roof panels and curing them to their design strength to form a rigid upper load-bearing structure, followed by formwork erection and concrete pouring for the walls and duct slabs. This allows for phased implementation of roof panel construction and the construction of the lower walls and duct slabs, reducing the difficulty of erecting a tall, composite formwork system in one go. By pre-embedding fiber cement sleeves in conjunction with overflow channels in the wall formwork, concrete feeding, vibration, observation, venting, and overflow are completed, enabling continuous filling of the wall pouring cavity and the duct slab pouring cavity. This improves the concrete density and forming quality of the walls, duct slabs, and their junctions, reducing the difficulty of high-altitude construction and construction safety risks.

[0019] This invention separates the roof panel pouring area from the wall area below by setting a wire mesh template along the entire vertical projection area of ​​the wall to be poured later. During the roof panel pouring process, it prevents concrete from flowing to the wall area below and forms a rough bonding interface at the junction of the roof panel and the wall to be poured later, thereby improving the bonding performance between the concrete poured later and later.

[0020] This invention involves setting multiple fiber cement sleeves at intervals along the length of the wall to be poured, and limiting the inner diameter, wall thickness, protrusion height, and spacing of the fiber cement sleeves. This allows concrete to enter the wall pouring cavity and the ventilation duct pouring cavity from multiple locations, shortening the lateral flow distance of the concrete within the pouring cavity. The fiber cement sleeves protrude from the roof panel at a predetermined height, and a removable sealing device is installed at the upper end of the fiber cement sleeve to prevent roof panel concrete, mortar, and construction debris from entering the sleeve, ensuring unobstructed flow for subsequent concrete pouring and vibration.

[0021] This invention arranges fiber cement sleeves and overflow channels in the wall formwork along the length of the wall, ensuring that each pouring section has corresponding locations for material feeding, vibration, observation, venting, and overflow. By having the fiber cement sleeves sequentially cooperate with the concrete delivery pump pipe and vibration equipment at different construction stages, the same sleeve can perform functions such as concrete feeding, layered vibration, and observation of the filling status, reducing the number of openings in the formwork and interference between different construction equipment. By controlling the pouring height of each layer of concrete and pouring the next layer after sufficient vibration, it helps to reduce concrete segregation, air bubble accumulation, honeycombing, and voids, and improves the pouring density at the junction of the top of the wall and the ventilation duct plate.

[0022] This invention constructs a roof panel support system using supporting steel beams, steel brackets, roof panel support frames, and wall ties. Pre-embedded cones are used to fix the steel brackets to the already poured wall, and the steel brackets support the supporting steel beams, ensuring that the roof panel construction load can be reliably transferred to the existing structure. The wall ties secure the roof panel support frame, improving the overall stability of the support system and reducing the risk of tilting or instability during high-altitude formwork erection of the roof panel. Simultaneously, it facilitates the installation, dismantling, and reuse of the support components.

[0023] This invention discharges air and excess concrete from the pouring cavity through the overflow channel of the wall template, and forms a cuttable overflow channel on the outside of the wall template, allowing construction workers to judge the filling status of the concrete based on the overflow status, reducing the problem of insufficient filling at the top of the wall; after cutting off the part of the fiber cement sleeve that is higher than the preset height of the roof panel, the upper end of the sleeve cavity is sealed with micro-expansion waterproof mortar, and a waterproof sealing layer is set at the junction of the sleeve and the roof panel concrete, reducing the risk of water seepage channels forming at the sleeve cut and improving the waterproof reliability of the roof structure. Attached Figure Description

[0024] Figure 1 : A schematic diagram of the construction method for the post-cast wall and air duct slab under the roof panel of the present invention.

[0025] Figure 2 : A cross-sectional schematic diagram of the roof panel support system and fiber cement sleeve pre-embedded structure during the roof panel casting of the present invention.

[0026] Figure 3 : A cross-sectional schematic diagram of the template and casting cavity structure during the pouring of the wall and air duct slab of the present invention.

[0027] Figure 4 : A partial structural diagram of the fiber cement sleeve and the overflow removal location of the present invention.

[0028] In the diagram: 1. Supporting steel beam; 2. Expansion bolt; 3. Bottom pressure plate of steel beam; 4. Template tie rod; 5. Tie rod fixing device; 6. Upper pressure plate of steel beam; 7. Nut; 8. Roof panel support frame; 9. Wall tie; 10. Operating frame; 11. Steel bracket; 12. Embedded cone; 13. Wall formwork; 14. Overflow channel; 15. Fiber cement sleeve; 16. Overflow fluid; 17. Wall reinforcement; 18. Bolt; 19. Wire mesh formwork; 20. Air duct plate support frame; 21. Scaffolding. Detailed Implementation

[0029] The present invention will be further described in detail below through specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0030] In one embodiment of the present invention, a construction method for post-cast walls and ventilation duct slabs under roof panels is provided, as illustrated in the flowchart below. Figure 1 As shown, it includes the following steps: S1: Erect the roof panel support system and lay the bottom formwork. Set up wire mesh templates in the vertical projection area of ​​the wall to be poured to separate the roof panel pouring area from the wall area below. Tie the roof panel reinforcement and wall reinforcement, and embed several fiber cement sleeves at intervals along the length of the wall. The fiber cement sleeves pass through the roof panel pouring area, and their lower ends pass through the wire mesh template and connect with the wall area. The upper end is higher than the preset height of the roof panel. S2: Pour concrete in the roof slab area and cure it to form a rigid superstructure; S3: Install wall formwork on the outside of the wall reinforcement, erect a duct plate support frame and install duct plate formwork. The wall formwork and duct plate formwork enclose each other to form a wall pouring cavity and a duct plate pouring cavity that are interconnected. Set an overflow trough for the wall formwork on the top of the wall formwork and connect it with the wall pouring cavity. S4: Concrete is delivered in layers to the wall pouring cavity and the air duct plate pouring cavity through the fiber cement sleeve. The vibrating equipment is inserted into the wall pouring cavity through the fiber cement sleeve to vibrate in layers, and the concrete filling status is observed through the fiber cement sleeve. Air and excess concrete in the pouring cavity are discharged through the wall formwork overflow channel and form an overflow on its outside. S5: After the concrete of the wall and duct slab reaches the strength required for the cutting operation, cut off the overflow along the designed outline of the wall, level the cut surface and continue to cure until the demolding strength is reached; remove the wall formwork, duct slab formwork and support frame, cut off the part of the fiber cement sleeve that is higher than the preset height of the roof panel, and trim the cut.

[0031] In step S1, a roof panel support system is erected according to the roof panel's elevation, span, and construction load, and a bottom formwork is laid on top of the roof panel support system. For example... Figure 2 As shown, the roof panel support system includes a supporting steel beam 1, a steel bracket 11, a roof panel support frame 8, and wall ties 9. One end of the supporting steel beam 1 is fixed or supported on the reference plane at the bottom of the structure, and the other end is supported on the steel bracket 11 fixed to the cast-in-place wall. The roof panel support frame 8 is erected on the supporting steel beam 1 and is connected and fixed to the cast-in-place wall through the wall ties 9.

[0032] A wire mesh template 19 is installed in the vertical projection area of ​​the wall to be poured, extending along the length of the wall and fixed to the underside of the roof slab reinforcement. The wire mesh template 19 uses galvanized steel wire mesh with a mesh size of 4-6mm, used to separate the roof slab pouring area from the area of ​​the wall to be poured below, and to form a rough bonding interface at the junction of the roof slab and the wall.

[0033] After setting up the wire mesh template 19, tie the roof slab reinforcement and wall reinforcement 17, and pre-embed multiple fiber cement sleeves 15 at intervals along the length of the wall to be poured. The inner diameter of the fiber cement sleeve 15 is 180-220mm, and the wall thickness is 15-25mm. Its lower end passes through the wire mesh template 19 and connects to the area of ​​the wall to be poured below. The upper end protrudes 200-300mm above the designed roof slab surface, and the spacing between adjacent fiber cement sleeves 15 is 1.5-2.0m. The fiber cement sleeves 15 are fixed to the roof slab reinforcement by positioning components to prevent the fiber cement sleeves 15 from tilting or shifting during the roof slab concrete pouring process.

[0034] Before pouring the roof slab concrete, a removable sealing device is installed at the upper end of each fiber cement sleeve 15 to temporarily seal the fiber cement sleeve 15 and prevent concrete, mortar or construction debris from entering the cavity of the fiber cement sleeve 15.

[0035] In step S2, the positions and fixation status of the bottom formwork, wire mesh template 19, roof panel reinforcement, wall reinforcement 17, and fiber cement sleeve 15 are first inspected. After passing the inspection, concrete is poured into the roof panel pouring area. During the pouring process, the wire mesh template 19 prevents the roof panel concrete from entering the area of ​​the wall to be poured below, and the removable sealing parts keep the inside of the fiber cement sleeve 15 unobstructed. After the roof panel is poured, the surface is smoothed and moisturized, and the strength of the roof panel concrete is determined by using specimens cured under the same conditions or other strength testing methods. After the roof panel concrete reaches 100% of its design strength, the roof panel forms a rigid upper load-bearing structure capable of supporting the subsequent formwork and pouring construction loads, and then the construction of the lower walls and ventilation duct slabs is carried out.

[0036] In step S3, as Figure 3 As shown, wall formwork 13 is installed on the outside of the wall reinforcement 17, and formwork tie rods 4 are used to reinforce the wall formwork 13. A ductwork support frame 20 is erected at the designed location of the ductwork slab, and ductwork slab formwork is installed, so that the wall formwork 13 and the ductwork slab formwork together enclose the wall casting cavity and the ductwork slab casting cavity, which are interconnected at their junction.

[0037] An overflow trough 14 is installed at the top of the wall formwork 13. The overflow trough 14 is connected to the wall pouring cavity, and its opening height is 100-150mm and its width is 150-200mm. It is arranged in sections along the length of the wall to be poured. Each fiber cement sleeve 15 corresponds to one overflow trough 14. The overflow trough 14 is located below the corresponding fiber cement sleeve 15 and is used to discharge air and excess concrete in the pouring cavity and to observe the filling status of the concrete in the corresponding pouring section.

[0038] In step S4, the detachable sealing piece at the upper end of the fiber cement sleeve 15 is removed, and the concrete delivery pump pipe is connected to the upper end of the fiber cement sleeve 15. Concrete is then delivered to the wall pouring cavity through the fiber cement sleeve 15. After entering the wall pouring cavity, the concrete enters the duct plate pouring cavity through the connection between the wall pouring cavity and the duct plate pouring cavity, completing the continuous pouring of the wall and the duct plate.

[0039] The concrete in the wall pouring cavity and the air duct slab pouring cavity is poured in layers, with each layer having a pouring height of 400–1000 mm. After each layer of concrete is poured, the concrete delivery pump pipe is removed from the top of the fiber cement sleeve 15, and then the vibrating equipment is inserted into the pouring cavity through the same fiber cement sleeve 15 to vibrate that layer of concrete. Additionally, the vibrating equipment can also vibrate the concrete in the pouring cavity by passing through the overflow trough 14. After vibration, the filling height and surface condition of the concrete are observed through the fiber cement sleeve 15 before pouring the next layer of concrete.

[0040] like Figure 4 As shown, as the concrete level rises, air in the pouring cavity is discharged through the overflow channel 14. When the concrete fills the wall pouring cavity and the air duct plate pouring cavity, excess concrete overflows from the overflow channel 14 and forms an overflow flow 16 on the outside of the overflow channel 14. By observing the overflow state of each overflow channel 14, the concrete filling status of the corresponding pouring segment can be determined.

[0041] In step S5, after the concrete of the wall and the duct slab reaches the strength required for the cutting operation, the overflow fluid 16 formed on the outside of the overflow groove 14 is cut off along the designed outline of the wall, and the cut surface is trimmed and leveled. After the cutting is completed, the concrete of the wall and the duct slab continues to be cured until it reaches the demolding strength, and then the wall formwork 13, the duct slab formwork, and the duct slab support frame 20 are removed.

[0042] The portion of the fiber cement sleeve 15 extending above the designed roof panel surface is cut off to ensure the cut end fits the roof panel surface. The upper end of the fiber cement sleeve 15 is sealed with micro-expansion waterproof mortar, and a waterproof sealant layer is applied at the junction of the fiber cement sleeve 15 and the roof panel concrete. Finally, the supporting steel beam 1, steel bracket 11, roof panel support frame 8, and wall ties 9 are removed, and the holes formed after the removal of the supporting components are sealed and repaired.

[0043] To further understand the technical solution of the present invention, a detailed description is provided in conjunction with specific embodiments: This embodiment is applied to the construction of the roof structure of an industrial building's machine room. The structure includes a roof panel, a shear wall located below the roof panel, and an air duct slab connected to the shear wall. The roof panel is 800mm thick, the air duct slab is 200mm thick, and the shear wall is 5.35m high.

[0044] A No. 16 I-beam is installed as a supporting steel beam 1 along the reference plane at the bottom of the structure. M16 expansion bolts 2 are used to pass through the bottom pressure plate 3 and the screw fixing device 5 of the steel beam to fix the supporting steel beam 1 to the reference plane at the bottom of the structure; the upper pressure plate 6 of the steel beam is clamped and locked with nuts 7. A steel bracket 11 is installed every 1.2m along the length of the poured wall. The steel bracket 11 is connected to the pre-embedded cone 12 set in the poured wall by M30 bolts 18, and the outer end of the supporting steel beam 1 is supported on the steel bracket 11. A scaffolding plank 21 is laid on the supporting steel beam 1 to form a construction operation platform.

[0045] A roof panel support frame 8 is erected on the supporting steel beam 1. The vertical spacing of the uprights of the roof panel support frame 8 is 1.2m, the horizontal spacing is 1.2m, and the vertical step distance is 1.5m. Vertical scissor bracing is also installed. A wall tie 9 is installed every 1.8m vertically to rigidly connect the roof panel support frame 8 to the already poured walls on both sides. A 15mm thick wooden formwork is laid on top of the roof panel support frame 8 as the bottom formwork for the roof panel.

[0046] A galvanized steel wire mesh with a mesh size of 5mm × 5mm is installed as a wire mesh template 19 in the vertical projection area of ​​the shear wall. The wire mesh template 19 is installed along the length of the shear wall and fixed to the underside of the bottom reinforcement of the roof slab. Subsequently, the roof slab reinforcement and the wall reinforcement 17 are tied.

[0047] A fiber cement sleeve 15 is pre-embedded every 1.8m along the length of the shear wall. The fiber cement sleeve 15 has an inner diameter of 200mm, a wall thickness of 20mm, and a total length of 1100mm, of which 800mm is located within the roof slab pouring area, and 300mm extends above the designed roof slab surface. Its lower end passes through the wire mesh template 19 and connects to the shear wall area below. The fiber cement sleeve 15 is fixed with positioning hoops connected to the roof slab reinforcement, and a removable rubber sealing cap is installed at the upper end of each fiber cement sleeve 15.

[0048] After the concealed acceptance inspection is completed, concrete is poured into the roof slab pouring area. During the pouring process, wire mesh formwork 19 prevents concrete from entering the shear wall area below, and rubber sealing caps prevent concrete and cement slurry from entering the fiber cement sleeve 15. After the roof slab concrete is poured, the surface is finished, covered, and moisturized for curing. After the roof slab concrete reaches 100% of its design strength as confirmed by testing specimens cured under the same conditions, the shear wall and air duct slab construction begins.

[0049] Wall formwork 13 is installed on the outside of the wall reinforcement 17, and is reinforced with 14mm diameter tie rods 4. A duct support frame 20 is erected below the duct slab and the duct slab formwork is installed thereon, ensuring the shear wall pouring cavity and the duct slab pouring cavity are connected at the junction. An overflow trough 14 is installed at the top of the wall formwork 13 and below each fiber cement sleeve 15, with a width of 180mm and a height of 120mm. A double-row operating frame 10 is erected on the outside of the wall formwork 13 for concrete pouring, observation, and subsequent cutting operations.

[0050] Before pouring concrete for the walls and duct slabs, remove the rubber sealing cap at the upper end of the fiber cement sleeve 15 and connect the concrete delivery pump pipe to the upper end of the fiber cement sleeve 15. Concrete is then delivered in layers to the shear wall pouring cavity through the fiber cement sleeve 15. The concrete enters the duct slab pouring cavity through the connection between the shear wall pouring cavity and the duct slab pouring cavity, and the pouring height of each layer of concrete is controlled at 500mm.

[0051] After pouring one layer of concrete, remove the concrete delivery pump pipe and insert a 50-type immersion vibrator through the same fiber cement sleeve 15 into the shear wall pouring cavity to vibrate the concrete layer. After vibration, remove the vibrator and observe the concrete filling height through the fiber cement sleeve 15 before pouring the next layer of concrete. Repeat the pouring, vibration, and observation process until concrete continuously overflows from each overflow trough 14 with no obvious air bubbles and a uniform consistency, then stop pouring. The overflowing concrete forms an overflow fluid 16 on the outside of the overflow trough 14.

[0052] After confirming that the concrete of the shear wall and duct slab had reached the required strength for cutting operations using test specimens under the same conditions, a cutting device equipped with a diamond cutting disc was used to remove the overflow fluid 16 along the designed contour surface of the shear wall, and the cut surface was leveled. The concrete of the shear wall and duct slab continued to be moisturized and cured until it reached the demolding strength. Then, the formwork tie rods 4, wall formwork 13, duct slab formwork, duct slab support frame 20, and operating frame 10 were removed in sequence.

[0053] Cut off the 300mm section of the fiber cement sleeve 15 that extends above the designed roof panel surface. Grind the cut end of the fiber cement sleeve 15 smooth and seal the upper cavity of the fiber cement sleeve 15 with micro-expansion waterproof mortar. Apply a polymer cement waterproof coating at the junction of the fiber cement sleeve 15 and the roof panel concrete, extending the waterproof coating at least 100mm beyond the surrounding roof panel surface at the junction.

[0054] Finally, the supporting steel beam 1, steel bracket 11, roof panel support frame 8, wall tie 9, and embedded cone 12 were removed, and the holes formed after the removal of the supporting steel beam 1, steel bracket 11, and embedded cone 12 were sealed with cement mortar.

[0055] After construction, the concrete connection between the shear wall and the air duct slab is continuous, and no obvious honeycomb, holes or grout leakage defects are found at the top of the wall and at the junction of the wall and the air duct slab. After sealing and waterproofing treatment, the cut of the fiber cement sleeve 15 is smoothly connected to the surface of the roof panel, with no risk of water seepage.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A construction method for post-cast walls and ventilation duct slabs under roof slabs, characterized in that, Includes the following steps: S1: Erect the roof panel support system and lay the bottom formwork. Set up a wire mesh template in the vertical projection area of ​​the wall to be poured to separate the roof panel pouring area from the wall area below. Tie the roof panel reinforcement and wall reinforcement, and embed several fiber cement sleeves at intervals along the length of the wall. The fiber cement sleeves pass through the roof panel pouring area, and their lower ends pass through the wire mesh template and connect with the wall area. The upper ends are higher than the preset height of the roof panel. S2: Pour concrete in the roof slab area and cure it to form a rigid superstructure; S3: Install wall formwork on the outside of the wall reinforcement, erect a duct plate support frame and install duct plate formwork. The wall formwork and duct plate formwork enclose each other to form a wall pouring cavity and a duct plate pouring cavity that are interconnected. Set an overflow trough for the wall formwork on the top of the wall formwork and connect it with the wall pouring cavity. S4: Concrete is delivered in layers to the wall pouring cavity and the air duct plate pouring cavity through the fiber cement sleeve. The vibrating equipment is inserted into the wall pouring cavity through the fiber cement sleeve to vibrate in layers, and the concrete filling status is observed through the fiber cement sleeve. Air and excess concrete in the pouring cavity are discharged through the wall formwork overflow channel and form an overflow on its outside. S5: After the concrete of the wall and duct slab reaches the strength required for the cutting operation, cut off the overflow along the designed outline of the wall, level the cut surface and continue to cure until the demolding strength is reached; remove the wall formwork, duct slab formwork and support frame, cut off the part of the fiber cement sleeve that is higher than the preset height of the roof panel, and trim the cut.

2. The construction method for post-cast walls and duct slabs under the roof slab according to claim 1, characterized in that: The wire mesh template is arranged along the length of the wall to be poured and fixed to the underside of the roof slab reinforcement; the wire mesh template is made of galvanized steel wire mesh with a mesh size of 4-6mm.

3. The construction method for post-cast walls and ventilation duct slabs under the roof slab according to claim 1, characterized in that: The fiber cement sleeve has an inner diameter of 180-220mm and a wall thickness of 15-25mm. Its upper end is 200-300mm above the pre-set height of the roof panel. The spacing between adjacent fiber cement sleeves along the length of the wall to be poured is 1.5-2.0m.

4. The construction method for post-cast walls and duct slabs under the roof slab according to claim 1, characterized in that: Before pouring concrete in the roof slab area, a removable sealing device is installed at the upper end of each fiber cement sleeve to seal the fiber cement sleeve; before conveying concrete through the fiber cement sleeve to the wall pouring cavity and the air duct plate pouring cavity, the removable sealing device is removed.

5. The construction method for post-cast walls and duct slabs under the roof slab according to claim 1, characterized in that: The overflow groove of the wall formwork has a groove height of 100-150mm and a width of 150-200mm, and the spacing between adjacent overflow grooves of the wall formwork along the length of the wall to be poured is 1.5-2.0m.

6. The construction method for post-cast walls and duct slabs under the roof slab according to claim 1, characterized in that: The fiber cement sleeves and wall formwork overflow channels are arranged in sections along the length of the wall to be poured. Each fiber cement sleeve corresponds to a wall formwork overflow channel, and the wall formwork overflow channel is located below the corresponding fiber cement sleeve.

7. The construction method for post-cast walls and duct slabs under the roof slab according to claim 1, characterized in that: In step S4, the concrete in the wall pouring cavity and the air duct plate pouring cavity is poured in layers. The pouring height of each layer of concrete is 400-1000mm. After each layer of concrete is poured and fully vibrated, the next layer of concrete is poured.

8. The construction method for post-cast walls and ventilation duct slabs under the roof slab according to claim 1, characterized in that: In step S4, concrete is transported using a concrete delivery pump pipe. The concrete delivery pump pipe and the vibration equipment are used in conjunction with the same fiber cement sleeve at different construction periods. The fiber cement sleeve serves as the concrete discharge channel, the vibration channel, and the concrete filling status observation channel in sequence.

9. The construction method for post-cast walls and duct slabs under the roof slab according to claim 1, characterized in that: The roof panel support system includes supporting steel beams, steel brackets, roof panel support frames, and wall ties; the steel brackets are fixed to the cast-in-place wall by pre-embedded cones; one end of the supporting steel beam is fixed to the reference surface at the bottom of the structure, and the other end is supported on the steel bracket; the roof panel support frame is erected on the supporting steel beam and is connected and fixed to the cast-in-place wall by a wall tie.

10. The construction method for post-cast walls and duct slabs under the roof slab according to claim 1, characterized in that: In step S5, after cutting off the portion of the fiber cement sleeve that extends above the preset height of the roof panel, the upper end cavity of the fiber cement sleeve is sealed with micro-expansion waterproof mortar, and a waterproof sealing layer is installed at the junction of the fiber cement sleeve and the roof panel concrete.

Images