Special hanging structure cast-in-situ fair-faced concrete ceiling board making method

Abstract

The application relates to the field of fair-faced concrete, in particular to a special suspended fair-faced concrete ceiling plate construction method, which comprises the following steps: arranging a steel structure purlin, suspending a joint on the steel structure purlin to form a formwork frame body; preparing fair-faced concrete to form a fair-faced concrete plate; supporting a double-layer fair-faced concrete plate; arranging an adjustable L bolt at the joint of the steel structure purlin; preliminarily fixing the L bolt; binding the fair-faced concrete reinforcing steel bars; on-site pouring the fair-faced concrete ceiling plate meeting the strength; secondarily fixing the L bolt before formwork removal; and removing the formwork after checking the stress condition of the L bolt. The application has the effect of avoiding joint gaps of the fair-faced concrete plates during splicing.

Description

Technical Field

[0001] This application relates to the field of fair-faced concrete, and in particular to a special suspended structure for cast-in-place fair-faced concrete ceiling panels. Background Technology

[0002] Fair-faced concrete is cast in one continuous pour without any secondary decoration. Its most distinctive feature is that after pouring, no coating, tiles, or stone cladding are applied, showcasing the raw, unadorned nature of concrete. However, to prevent rainwater penetration or deterioration, a waterproofing agent may be sprayed on. Fair-faced concrete slabs are formed by a combination of regularly arranged tie bolt holes, visible joints, chamfered joints, and artificial eyelets, ensuring the overall aesthetic appeal of the building and achieving the highest quality standards for fair-faced concrete.

[0003] The quality requirements for fair-faced concrete are very high, particularly regarding points, lines, and surfaces. Points refer to accurate positioning and uniform distribution; lines refer to regular forming patterns and smooth outlines; and surfaces refer to a flat surface and uniform color. Currently, when fair-faced concrete is used for, for example, 20*20m roof cladding panels, it is mostly precast and then assembled on-site. However, on-site assembly results in seams, affecting the aesthetics. Summary of the Invention

[0004] To avoid seams during the splicing of fair-faced concrete slabs, this application provides a special suspended structure for cast-in-place fair-faced concrete ceiling slabs.

[0005] This application provides a special suspended structure for cast-in-place fair-faced concrete ceiling panels, employing the following technical solution:

[0006] A method for constructing a special suspended structure cast-in-place fair-faced concrete ceiling slab includes the following steps:

[0007] Steel purlins are installed, and nodes are suspended on the steel purlins to form a formwork frame.

[0008] To produce fair-faced concrete, forming fair-faced concrete slabs;

[0009] Support a double-layer water-concrete slab;

[0010] Adjustable L-bolts are installed at the suspension nodes of the rigid purlins;

[0011] Initially secure the L-bolts;

[0012] Perform steel reinforcement binding for fair-faced concrete;

[0013] On-site pouring of fair-faced concrete ceiling slabs that meet the required strength;

[0014] Before demolding, the L-bolts should be secured a second time.

[0015] After checking the stress on the L bolts, disassemble the formwork.

[0016] By adopting the above technical solution, the L-bolts at the nodes can be adjusted vertically, and the L-bolts in the middle of the roof can be adjusted upwards by a certain distance, lifting the fair-faced concrete in the middle of the roof and reducing its deflection. Simultaneously, the L-bolts can move back and forth and side to side within the holes of the steel purlins. When the fair-faced concrete expands and contracts due to temperature changes, the lower end of the L-bolt will move to a certain extent, reducing the risk of cracking. This construction method provides a way to construct cast-in-place fair-faced concrete ceiling panels, effectively solving the problems of traditional precast suspension construction methods and improving productivity.

[0017] Preferably, the L-bolt is a load-bearing suspension component, and the formwork support frame has a fixing hole for the L-bolt to be movably positioned. The L-bolt is provided with a detachable nut, which allows the L-bolt to switch between a movable state and a fixed state.

[0018] By adopting the above technical solution, since the L-bolt is fixed by drilling holes in the flange of the steel structure beam with nuts, before pouring, in order to control the shaking that would cause the L-bolt to detach from the steel mesh and affect the connection, a nut is set at the top and bottom of the steel structure beam to fix the L-bolt. After the pouring is completed, the bottom nut is loosened to make it movable, so as to ensure that the shrinkage force generated by the concrete during the heat of hydration is not constrained.

[0019] Preferably, the method of supporting the double-layer water-concrete slab includes the following steps:

[0020] Prepare a 12mm thick formwork specifically for fair-faced concrete;

[0021] Double-layer 12mm fair-faced concrete special formwork is cut using a 3D model and a fully automatic formwork cutting machine;

[0022] The concrete is arranged neatly and orderly on the formwork according to the detailed design, and is used to form the fair-faced concrete finish.

[0023] Preferably, the step of providing an adjustable L-bolt at the suspension node of the rigid purlin includes:

[0024] The structural framework of fair-faced concrete is constructed using reinforced concrete.

[0025] The stress points of the fair-faced concrete structural frame are tied and fixed with L bolts.

[0026] Preferably, the initial fixing of the L-bolt includes the following steps:

[0027] Secure the first nut to the bottom of the L-bolt;

[0028] Hang L-bolts under the steel structure purlins;

[0029] The height of the bottom of the L-bolt from the special formwork for fair-faced concrete is determined on site.

[0030] Install the second nut on the steel purlin.

[0031] Preferably, the on-site casting of the fair-faced concrete ceiling slab meeting the required strength includes the following steps:

[0032] Determine the strength requirements, and pour 3-50mm fair-faced concrete ceiling slabs on site. Depending on the building's finish, pour them together with the reinforcing steel. During pouring, use a flat vibrator and a special high-frequency vibrator for fair-faced concrete to work simultaneously. After forming, achieve the desired finish for the building.

[0033] By adopting the above technical solution, the finished surface is more complete after molding and the joint seams are avoided, making the surface more beautiful.

[0034] Preferably, the secondary fixing of the L-bolts before demolding includes the following steps:

[0035] Loosen the first nut downwards and tighten the second nut;

[0036] Make sure the second nut of the L bolt is tightly attached to the steel purlin;

[0037] Apply the self-weight load of the fair-faced concrete ceiling slab to the steel structure.

[0038] Preferably, the end of the L-bolt extends into the bottom of the reinforcing bar inside the concrete and is tied to the reinforcing bar. The tail of the L-bolt is inserted into the reserved hole of the purlin and fixed to the purlin with a load-bearing nut. After tightening before demolding, the exposed parts are coated with anti-corrosion treatment.

[0039] Preferably, the steel purlin acts on the steel frame beam of the steel structure to suspend L bolts and bear the self-weight load of fair-faced concrete. Holes are opened on the purlins for L bolts to pass through.

[0040] Preferably, the method also includes the step of: after the pouring is completed, wet curing is adopted, and the formwork is removed after the conditions for demolding of fair-faced concrete are met.

[0041] In summary, this application includes at least one of the following beneficial technical effects:

[0042] 1. The L-bolts at the joints are adjustable vertically. The L-bolt in the middle of the roof can be adjusted upwards by a certain distance to lift the fair-faced concrete in the middle of the roof, reducing its deflection. Simultaneously, the L-bolts can move back and forth and side to side within the holes of the steel purlins. When the fair-faced concrete expands and contracts due to temperature changes, the lower end of the L-bolt will move slightly, reducing the risk of cracking. This construction method provides a way to construct cast-in-place fair-faced concrete ceiling panels, effectively solving the problems of traditional precast suspension construction methods and improving productivity.

[0043] 2. Since the L-bolts are fixed by holes drilled in the flange of the steel structure beam with nuts, before pouring, in order to control the shaking that would cause the L-bolts to detach from the steel mesh and affect the connection, a nut is set at the top and bottom of the steel structure beam to fix the L-bolts. After the pouring is completed, the bottom nut is loosened to make it movable, so as to ensure that the shrinkage force generated by the concrete during the heat of hydration is not constrained. Attached Figure Description

[0044] Figure 1 This is a schematic diagram illustrating the process of constructing a special suspended structure cast-in-place fair-faced concrete ceiling panel according to an embodiment of this application. Detailed Implementation

[0045] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.

[0046] This application discloses a method for constructing a special suspended structure cast-in-place fair-faced concrete ceiling slab. (Refer to...) Figure 1 The construction process for a special suspended structure cast-in-place fair-faced concrete ceiling panel includes the following steps:

[0047] S1. Install steel purlins and suspend nodes on the steel purlins to form a formwork frame;

[0048] S2. Produce fair-faced concrete to form fair-faced concrete slabs;

[0049] S3. Support double-layer water-concrete slabs;

[0050] The steps for setting up a double-layer water-resistant concrete slab are as follows:

[0051] Prepare a 12mm thick formwork specifically for fair-faced concrete;

[0052] Double-layer 12mm fair-faced concrete special formwork is cut using a 3D model and a fully automatic formwork cutting machine;

[0053] The concrete is arranged neatly and orderly on the formwork according to the detailed design, and is used to form the fair-faced concrete finish.

[0054] S4. Adjustable L-bolts are installed at the suspension nodes of the rigid purlins;

[0055] The steps for installing adjustable L-bolts at the purlin suspension nodes of the rigid structure include:

[0056] The structural framework of fair-faced concrete is constructed using reinforced concrete.

[0057] The stress points of the fair-faced concrete structural frame are tied and fixed with L bolts.

[0058] Among them, the L-bolt is a load-bearing suspension component. The formwork support frame has a fixing hole for the L-bolt to be moved. The L-bolt is equipped with a detachable nut, which allows the L-bolt to switch between a movable state and a fixed state. The detachable nut includes a first nut and a second nut. Furthermore, the steel structure purlin acts on the steel structure frame beam to suspend the L-bolt and bear the self-weight load of the fair-faced concrete. The purlin has a hole for the L-bolt to pass through.

[0059] S5. Initially fix the L bolts;

[0060] The initial fixing of the L-bolt includes the following steps:

[0061] Secure the first nut to the bottom of the L-bolt;

[0062] Hang L-bolts under the steel structure purlins;

[0063] The height of the bottom of the L-bolt from the special formwork for fair-faced concrete is determined on site.

[0064] Install the second nut on the steel purlin.

[0065] S6. Perform steel reinforcement binding for fair-faced concrete;

[0066] S7. Cast fair-faced concrete ceiling panels of the required strength on site;

[0067] The process of pouring on-site fair-faced concrete ceiling slabs that meet the required strength includes the following steps:

[0068] Determine the strength requirements, and pour 3-50mm fair-faced concrete ceiling slabs on site. Depending on the building's finish, pour them together with the reinforcing steel. During pouring, use a flat vibrator and a special high-frequency vibrator for fair-faced concrete to work simultaneously. After forming, achieve the desired finish for the building.

[0069] S8. Before demolding, the L bolts are fixed again.

[0070] The secondary fixing of L-bolts before demolding includes the following steps:

[0071] Loosen the first nut downwards and tighten the second nut;

[0072] Make sure the second nut of the L bolt is tightly attached to the steel purlin;

[0073] Apply the self-weight load of the fair-faced concrete ceiling slab to the steel structure.

[0074] Furthermore, the end of the L-bolt is inserted into the bottom of the reinforcing steel in the concrete and tied to the reinforcing steel. The tail of the L-bolt is inserted into the reserved hole of the purlin and fixed to the purlin with a load-bearing nut. After tightening before demolding, the exposed parts are coated with anti-corrosion treatment.

[0075] S9. After checking the stress on the L bolts, disassemble the formwork:

[0076] Optionally, after pouring, wet curing can be used, and the formwork can be removed after the concrete reaches the conditions for demolding.

[0077] The L-bolts at the nodes are adjustable vertically, and the L-bolts in the middle of the roof can be adjusted upwards by a certain distance to lift the fair-faced concrete in the middle of the roof and reduce its deflection. Simultaneously, the L-bolts can move back and forth and left and right within the holes of the steel purlins. When the fair-faced concrete expands and contracts due to temperature changes, the lower end of the L-bolt will move to a certain extent, reducing the risk of cracking. This construction method provides a way to construct cast-in-place fair-faced concrete ceiling panels, effectively solving the problems of traditional precast suspension construction methods and improving productivity. Since the L-bolts are fixed by nuts through holes drilled in the flange of the steel beam, before pouring, to control the swaying that could cause the L-bolts to detach from the reinforcing mesh and affect the connection, a nut is installed at the top and bottom of the steel beam to fix the L-bolts. After pouring, the bottom nut is loosened, allowing it to move freely and ensuring that the shrinkage force generated during the hydration heat of the concrete is not constrained.

[0078] In an optional embodiment, since there is no space for the ceiling panel to be tightened to prevent cracking, 70% of the original structural camber value is used as the tightening value of the ceiling panel. That is, the tightening value at the mid-span of the variable cross-section secondary beam is: (absolute deflection value of GTL + camber value of the variable cross-section secondary beam in the original drawing, deflection due to the self-weight of the steel beam) × 70%; the tightening value at the mid-span of the variable cross-section main beam is: (camber value of the variable cross-section main beam in the original drawing, deflection due to the self-weight of the steel beam) × 70%. The tightening value of the ceiling panel indicates that the tightening values ​​at the mid-span, CTL beam, and edge beam positions of each variable cross-section beam are connected by a line; the camber height at the purlin positions with a 1m spacing is linearly interpolated based on the line obtained in step 1; the tightening values ​​at each purlin position of each variable cross-section beam are symmetrical about the mid-span.

[0079] In one optional embodiment, the fair-faced concrete ceiling slab is constructed in three spans as one construction section. Optionally, 50 construction sections are set up, and the skip-pour construction method is adopted. An 8mm expansion joint is left between every three spans of concrete. The expansion joint uses a single-sided adhesive-coated 8mm thick gray environmentally friendly silicone foam board as the partition. In a preferred embodiment, during construction, the first pour of the fair-faced concrete ceiling slab uses a 2-8mm gray silicone foam board; the second pour uses a 4-0.42mm rigid PVC board. After the ceiling slab is cast, once the concrete in each three-span construction section reaches the required strength, a crack-resistant loading is applied according to the design value to increase the crack resistance and reduce the risk of cracking.

[0080] In an optional embodiment, the tensile force of each bolt is determined based on the mass of the ceiling panel. Ceiling panel mass = ceiling panel area × thickness × density = 120 × 0.05 × 2.5 = 15t; tensile force of each bolt = ceiling panel weight ÷ number of bolts = 15000 / 480 = 31.25kg. The bolt diameter is known to be 10mm, and the material is Q195b galvanized steel. According to the formula, 1N × m = 10.2kgf.cm, and the torque of a 10mm diameter nut is 135 × 10.2 = 1377kgf.cm. Therefore, theoretically, the nut and bolt meet the loading requirements. However, calculations show that when the nut is simultaneously tightened to a height of 10mm and the number of sets is less than 11, the nut will experience ultimate failure. Therefore, the nut height should be ≤3mm at a time, and the ceiling panel should be tightened in batches to lift it into place.

[0081] According to the structural stress requirements, after the concrete pouring is completed and the strength reaches the design requirements, clean all debris from the surface of the ceiling panel. After confirming the three-point tightening value, use fishing line to fix the steel beam and pull out the relative clear height between the upper surface of the ceiling panel and the bottom of the steel beam to be loaded. Then mark the data on the lower bolts of the main and secondary beams of the steel structure, and mark the bolt threads with a red marker. During construction, in an optional embodiment, when loading, two people are arranged between each steel beam. First, lift the nut of the upper bolt in the middle of the span by 2mm. Then, the two people load the remaining purlin bolts in different directions. Pay attention to the red markings and the height of the fishing line near the edge beam. It is strictly forbidden to load too high. Load 2mm high each time.

[0082] To ensure construction safety, in one optional embodiment, after each tightening operation, the height relationship between the edge beams, secondary beams, and ceiling slab is checked. When the fishing line near the edge beam is in contact with the ceiling slab, the outer loading work is stopped until the mid-span height loading is completed, the red marks on the bolts are completely hidden, and the fishing line is completely in contact with the ceiling slab surface. After the loading and lifting are completed, first check the separation of the three-span edge fair-faced concrete ceiling slab from the formwork, and whether the separation height is consistent with the loading and tightening height. If they are inconsistent, the error needs to be checked and appropriate adjustments made. Then check whether each bolt is tightened. For bolts that are not tightened, tighten them by hand until they are in contact with the steel structure purlins to ensure that the ceiling slab is under uniform stress. In one optional embodiment, after loading is completed, the L-bolts and nuts exposed to the air are fully sealed with polyurethane sealant.

[0083] The specific steps involved in constructing a special suspended structure cast-in-place fair-faced concrete ceiling panel include:

[0084] By setting up double-layer 12mm special formwork for fair-faced concrete, the flatness and installation quality of the formwork must meet the specifications to ensure the finishing effect after the fair-faced concrete is poured.

[0085] Hang L-bolts under the steel structure purlins. Before hanging the second L-bolt, the fixing nut at the bottom of the first L-bolt should be installed in place. Protect the threaded parts that are easily contaminated by concrete to prevent the nut from becoming unable to rotate due to concrete contamination. Determine the fixing position of the fixing nut at the bottom of the L-bolt by determining the height of the bottom of the L-bolt from the formwork on site, ensuring that the protective layer thickness of the fair-faced concrete reinforcement meets the design requirements. Then install the top load-bearing nut of the second L-bolt and tighten it onto the steel structure purlin.

[0086] Next, the reinforcement bars for the fair-faced concrete are tied, with each intersection of the bars fully bound with double-stranded wire, the ends of the wires aligned with the direction of the upper layer of reinforcement. At the L-bolt locations, the wires are fully bound in a crisscross pattern. Ensure the protective layer thickness at each location meets design requirements. Pour 3-50mm thick fair-faced concrete ceiling slabs to the required design strength on-site. Use both a flat vibrator and a dedicated high-frequency vibrator for fair-faced concrete during pouring to ensure the quality of the concrete. After pouring, use a wet curing method until the conditions for demolding the fair-faced concrete are met. Before demolding, loosen the bottom fixing nut of the first bolt downwards, then tighten the top tension nut of the L-bolt, ensuring it is flush against the steel purlin, thus applying the self-weight of the fair-faced concrete ceiling slab to the steel structure. Remove the formwork. Check the stress on each L-bolt, adjust those requiring adjustment, and after inspection, perform anti-corrosion treatment and clean the site.

[0087] The implementation principle of this application embodiment is as follows: the L-bolts at the nodes can be adjusted up and down, and the L-bolts in the middle of the roof can be adjusted upwards by a certain distance to lift the fair-faced concrete in the middle of the roof and reduce the deflection of the fair-faced concrete in the middle of the roof. At the same time, the L-bolts can swing back and forth and left and right in the holes of the steel structure purlins. When the fair-faced concrete expands and contracts with temperature changes, the lower end of the L-bolt will move to a certain extent, reducing the risk of cracks in the fair-faced concrete. This construction method provides a method for casting-in-place fair-faced concrete ceiling panels, effectively solving the problems of traditional precast suspension construction methods and improving productivity. Since the L-bolts are fixed by holes drilled in the flange of the steel structure beam with nuts, before pouring, in order to control the shaking that could cause the L-bolts to detach from the steel mesh and affect the connection, a nut is set at the top and bottom of the steel structure beam to fix the L-bolts. After pouring is completed, the bottom nut is loosened to allow it to move, ensuring that the shrinkage force generated by the concrete during the heat of hydration is not constrained.

[0088] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for constructing a special suspended structure cast-in-place fair-faced concrete ceiling slab, characterized in that, Including the following steps: Install steel purlins and suspend nodes on the steel purlins; To produce fair-faced concrete, forming fair-faced concrete slabs; Support double-layer fair-faced concrete slabs; Adjustable L-bolts are installed at the suspension nodes of the rigid purlins; Initially secure the L-bolts; Perform steel reinforcement binding for fair-faced concrete; On-site pouring of fair-faced concrete ceiling slabs that meet the required strength; Before demolding, the L-bolts should be secured a second time. After checking the stress on the L-bolts, disassemble the formwork. The L-bolt is a load-bearing suspension component. The steel purlin has a fixing hole for the L-bolt to be movably positioned. The L-bolt is equipped with a detachable nut, which allows the L-bolt to switch between a movable state and a fixed state. The detachable nut includes a first nut and a second nut. In the movable state, the L-bolt can swing back and forth and left and right in the hole of the steel purlin.

2. The construction method for a special suspended structure cast-in-place fair-faced concrete ceiling slab according to claim 1, characterized in that: The steps for supporting the double-layer fair-faced concrete slab are as follows: Prepare a 12mm thick formwork specifically for fair-faced concrete; Double-layer 12mm fair-faced concrete special formwork is cut using a 3D model and a fully automatic formwork cutting machine; The concrete is arranged neatly and orderly on the formwork according to the detailed design, and is used to form the fair-faced concrete finish.

3. The construction method for a special suspended structure cast-in-place fair-faced concrete ceiling slab according to claim 2, characterized in that: The steps for installing adjustable L-bolts at the suspension nodes of the rigid purlins include: The structural framework of fair-faced concrete is constructed using reinforced concrete. The stress points of the fair-faced concrete structural frame are tied and fixed with L bolts.

4. The construction method for a special suspended structure cast-in-place fair-faced concrete ceiling slab according to claim 3, characterized in that: The initial fixing of the L-bolt includes the following steps: Secure the first nut to the bottom of the L-bolt; Hang L-bolts under the steel structure purlins; The height of the bottom of the L-bolt from the special formwork for fair-faced concrete is determined on site. Install the second nut on the steel purlin.

5. The construction method for a special suspended structure cast-in-place fair-faced concrete ceiling slab according to claim 1, characterized in that: The process of casting fair-faced concrete ceiling slabs that meet the required strength on-site includes the following steps: Determine the strength requirements, and pour 3-50mm fair-faced concrete ceiling slabs on site. Depending on the building's finish, pour them together with the reinforcing steel. During pouring, use a flat vibrator and a special high-frequency vibrator for fair-faced concrete to work simultaneously. After forming, achieve the desired finish for the building.

6. The construction method for a special suspended structure cast-in-place fair-faced concrete ceiling slab according to claim 4, characterized in that: The secondary fixation of the L-bolts before demolding includes the following steps: Tighten the first nut; Make sure the first nut of the L-bolt is tightly attached to the steel purlin; Apply the self-weight load of the fair-faced concrete ceiling slab to the steel structure.

7. The construction method for a special suspended structure cast-in-place fair-faced concrete ceiling slab according to claim 6, characterized in that: The end of the L-bolt is inserted into the bottom of the reinforcing bar in the concrete and tied to the reinforcing bar. The tail of the L-bolt is inserted into the reserved hole of the purlin and fixed to the purlin with a load-bearing nut. After tightening before demolding, the exposed parts are coated with anti-corrosion treatment.

8. The construction method for a special suspended structure cast-in-place fair-faced concrete ceiling slab according to claim 1, characterized in that: The steel purlins act on the steel frame beams of the steel structure to suspend L-bolts and bear the self-weight load of the fair-faced concrete. Holes are opened on the purlins for the L-bolts to pass through.

9. The method for constructing a special suspended structure cast-in-place fair-faced concrete ceiling slab according to claim 1, characterized in that: It also includes the following steps: after the pouring is completed, wet curing is used, and the formwork is removed after the fair-faced concrete reaches the demolding conditions.

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