One-time forming mold and pouring process for UHPC core column ribbed plate

Abstract

The application discloses a one-time forming die and pouring process for a UHPC core column rib plate, and belongs to the technical field of concrete prefabricated component manufacturing. The die comprises a bottom die, a side die and a rib forming part, a negative pressure cavity in communication with a vacuum source is arranged in the bottom die and / or the side die, and a plurality of air-permeable micropores are arranged on the forming surface of the negative pressure cavity. A multi-point pressurized grouting flow channel system in communication with a concrete pump is arranged at the bottom of the die, the flow channel is arranged along the core column root and the lower skin plate area, UHPC is poured by adopting a bottom pumping and jacking mode from bottom to top, air and excess slurry are discharged through a top exhaust port, and the lower layer and the rib part concrete are fully filled and compacted. The application significantly improves the one-time forming quality, impermeability and anti-seismic performance of the UHPC core column rib plate module, and simplifies the factory production process.

Description

Technical Field

[0001] This invention relates to the field of precast concrete component manufacturing technology, and more particularly to a one-time molding mold for ultra-high performance concrete (UHPC) core column rib sandwich components and its matching bottom reverse casting process. Background Technology

[0002] Due to its high strength, high durability, and excellent impermeability and crack resistance, UHPC has been widely used in prefabricated buildings and bridge engineering. To achieve lightweight structure and high thermal insulation performance, the "sandwich" type UHPC core-rib plate modular unit, consisting of an upper skin plate, lightweight core material, core column ribs, and a lower skin plate, is gradually being adopted in engineering projects. It is prefabricated in the factory and then assembled on site to improve construction efficiency and quality.

[0003] A search of existing patents and literature related to UHPC precast components, sandwich panels, and negative pressure molding revealed that common solutions in the prior art mainly include: 1) using ordinary steel molds or combined steel molds, pouring UHPC from top to bottom by gravity, with foam or other lightweight core materials positioned by simple support, glue application, or through-steel reinforcement; 2) to prevent the core material from floating, inserting steel bars, bolts, or plastic connectors into the core material to mechanically connect it to the upper and lower skin plates; 3) for complex rib and core column structures, layered or multi-stage pouring is usually used: first pouring the lower skin plate and part of the rib columns, then pouring the upper skin plate above the core material; 4) although there are processes in other material molding fields that utilize negative pressure adsorption to fix the inlays or vacuum-assisted injection, these are mostly applied to resin composite materials or ordinary mortar products, and the corresponding mold structures and process parameters are not suitable for UHPC core column rib sandwich systems with high fluidity and special particle size distribution.

[0004] The aforementioned existing technologies still have the following prominent problems:

[0005] (1) It is difficult to form a whole in one step.

[0006] For "sandwich" components containing multiple core columns and complex ribs, when using top-down gravity casting, the UHPC flow path is long, which easily leads to air pockets or vibration dead zones at the base of the core columns and in low-lying areas of the lower skin plate. This results in honeycomb-like surface defects and localized incomplete compaction, making it difficult to guarantee compressive and fatigue resistance. To ensure molding quality, layered casting is often forced, which introduces the risk of cold joints.

[0007] (2) Layered casting is prone to cold joints, which affect the integrity and seismic performance.

[0008] When the lower skin plate and some ribs are poured first, and then the upper UHPC is poured, construction intervals are inevitable. The lower UHPC has already initially set, and cold joints are formed at the interface between the two pours. This weakens the overall performance of the ribs and the upper and lower skins, reduces the shear bearing capacity and seismic ductility, and is particularly unfavorable to the requirements for joint ductility in prefabricated assembled structures.

[0009] (3) The core material is unstable in positioning and is prone to forming thermal bridges and water seepage channels.

[0010] Currently, mechanical ties using steel bars or bolts penetrating the foam core material are commonly used to counteract the buoyancy and lateral pressure during UHPC casting. On the one hand, it is difficult to precisely position the core material, and displacement or torsion may still occur during casting and vibration, affecting the geometric accuracy and stress path of the component; on the other hand, rigid connectors penetrating the core material form thermal bridges and potential water seepage paths, weakening the insulation and durability performance of the sandwich panel, which is particularly disadvantageous in ultra-low energy buildings and applications in extremely cold regions.

[0011] (4) Restricted vibration and difficulty in removing air bubbles

[0012] Under conditions of dense reinforcement and multi-ribbed, multi-core column arrangement, conventional immersion vibrators are difficult to effectively reach all critical sections, and over-vibration can easily cause core material damage or displacement. For high-flow-rate UHPC, it is difficult to remove air trapped at the root of the core column in time through a single top surface venting, resulting in hidden voids, reducing local load-bearing capacity and fatigue resistance.

[0013] (5) The applicability of existing negative pressure and bottom pumping technologies is limited.

[0014] Existing technologies related to negative pressure adsorption or vacuum infusion are mostly aimed at fiber composite panels, ordinary concrete slabs, or small components. Their mold cavity shapes are relatively simple, and the requirements for precise three-dimensional positioning of the embedded core material are low. Moreover, they do not involve complex "sandwich" systems like UHPC core column rib plates, which simultaneously have lightweight cores, vertical core columns, and reinforcing ribs. On the other hand, although bottom pumping molding technology has been applied in large-volume concrete or hydraulic structures, it usually does not combine microporous negative pressure adsorption for precise positioning of the lightweight core material, nor does it address the issue of air pockets easily forming at the roots of multiple ribs in core column rib plates by optimizing the multi-point grouting flow channel design.

[0015] The comprehensive search results show that no mold or process solution has been found that simultaneously utilizes the microporous negative pressure adsorption of the mold forming surface to achieve three-dimensional precise positioning of the foam core material for UHPC core-rib sandwich components, and combines this with a bottom-up multi-point pressurized grouting channel to achieve a one-time integral reverse casting. Existing solutions are mostly simple combinations of traditional gravity casting and mechanical fixation of the core material, which cannot fundamentally solve key issues such as core material stability, cold joint control, and the dense molding of the lower UHPC.

[0016] Therefore, it is necessary to propose a new mold structure and supporting process that combines negative pressure adsorption positioning with multi-point reverse casting at the bottom. Without introducing penetrating tie-in components, the foam core material can be reliably fixed, and the high self-leveling properties of UHPC can be fully utilized to ensure the one-time casting quality of the core column rib plate. This will improve the seismic resistance, durability and thermal insulation performance of the component, and meet the manufacturing requirements of "one-time casting" of factory-made modular units. Summary of the Invention

[0017] This invention addresses the following problems existing in the factory-casting process of UHPC "sandwich" core column and rib plate components: Gravity casting from top to bottom leads to difficulties in vibration and air venting at the core column root, rib plate root, and low-lying areas of the lower skin plate, resulting in localized honeycomb surfaces, voids, and insufficient compaction, making it difficult to guarantee mechanical properties and durability; To prevent lightweight core materials such as foam from floating and shifting, steel bars, bolts, or plastic connectors penetrating the core material are commonly used for fixation, forming thermal bridges and potential seepage channels, weakening the insulation and impermeability of the sandwich component; Under complex rib plate and core column arrangements, layered or multi-stage casting is often required, leading to cold joints between the upper and lower UHPCs, weakening the overall integrity and seismic performance of the component; Existing negative pressure adsorption or bottom pumping technologies are mostly used for simple cross-sections or other material systems and cannot meet the comprehensive requirements of "three-dimensional precise core material positioning + multi-point compaction at the bottom + one-time integral casting" for UHPC core column and rib plate sandwich components.

[0018] The purpose of this invention is to provide a molding die and casting process for UHPC core column ribs. By constructing a microporous negative pressure adsorption system on the molding surface of the die and arranging multiple pressurized grouting channels inside the bottom mold, stable and non-penetrating positioning of the foam core material and uniform filling and degassing of the UHPC grout from bottom to top are achieved, thereby significantly improving the one-time molding quality of the component and avoiding cold joint and thermal bridge problems.

[0019] To achieve the above objectives, the technical solution provided by this invention is summarized as follows:

[0020] 1. Overall structure of the molding die

[0021] The mold includes a bottom mold (1), side molds (2) surrounding the bottom mold, and an optional top mold or cover plate (25). The bottom mold (1) has a lower skin forming surface (20) for forming the lower skin, and the side molds (2) and / or the top mold (25) have an upper skin forming surface (19) for forming the upper skin, forming a space within the mold cavity for arranging the UHPC core pillars (17), UHPC ribs (18), and foam core material (16). The outside of the mold is equipped with a mold frame support (24).

[0022] 2. Negative pressure adsorption positioning system

[0023] The bottom mold (1) and / or the side mold (2) are provided with a negative pressure cavity (3) extending along the length and width of the component. The negative pressure cavity (3) is connected to the vacuum source (14) through a negative pressure pipeline (4). Several permeable micropores (5) are evenly distributed on the molding surface facing the mold cavity. The pore diameter and pore spacing of the permeable micropores (5) are determined according to the particle size distribution of UHPC and the stiffness of the core material to take into account both adsorption capacity and anti-clogging performance. The negative pressure cavity (3) can be set in sections along the core column arrangement area and the rib arrangement area. It is connected to the vacuum source (14) through different negative pressure pipelines (4) to realize independent adsorption control of the sections. Sealing ribs (6) and elastic sealing strips (7) that fit with the foam core material (16) are set at the contact parts of the bottom mold (1) and / or the side mold (2) to form a local sealed chamber, improve the negative pressure retention capacity, and prevent the slurry from seeping into the negative pressure cavity (3) during the pouring process.

[0024] With the above structure, before casting, the foam core material (16) is attached to the molding surfaces of the bottom mold (1) and the side mold (2) according to the design position. After the vacuum source (14) is started, negative pressure is applied to the surface of the core material through the air-permeable micropores (5) to adsorb and lock the core material in the three-dimensional predetermined position. There is no need to set rigid connectors that penetrate the core material.

[0025] 3. Multi-point pressurized grouting channel system

[0026] A main grouting channel (8) is set inside the bottom mold (1) along the length of the component. The main channel (8) is connected to the concrete pump (15) through the grout inlet (10). Several grouting branch channels (9) branch out from the main channel (8) and extend to the root of the core column, the root of the rib plate and the low-lying area of ​​the lower skin plate forming surface (20). The grout outlet (11) is arranged at the corresponding position. The grout outlet (11) is preferably arranged facing upward or inclined towards the junction of the core column (17) and the rib plate (18) so that the grout fills the key nodes from bottom to top. The cross-sectional dimensions, branch spacing and elevation of the channel system are optimized according to the component height and the flow characteristics of UHPC to ensure that the grout front rises uniformly and synchronously.

[0027] Vents (12) and / or overflow ports (13) connected to the mold cavity are provided on the side mold (2) and / or top mold (25). A filter or a breathable component may be installed in the vent (12). If necessary, an observation window (22) or a pressure sensor (23) may be arranged near the vent to monitor the rise height of the slurry and the pressure inside the mold cavity.

[0028] 4. Reverse casting process

[0029] The process for preparing UHPC core pillar ribs using the above-mentioned mold includes:

[0030] S1: Place the steel reinforcement skeleton (21) in the bottom mold (1) and the side mold (2), and arrange the foam core material (16) according to the design position so that it fits tightly with the bottom mold forming surface (20), the side mold forming outline and the core column and rib plate cavity;

[0031] S2: Start the vacuum source (14), draw air into the negative pressure chamber (3) through the negative pressure pipeline (4), apply negative pressure adsorption to the foam core material (16) through the air-permeable micropores (5), thereby achieving three-dimensional stable positioning of the core material, and the vacuum degree can be adjusted in zones as needed;

[0032] S3: Connect the mixed UHPC to the concrete pump (15), and supply grout from bottom to top to the main channel (8) of the grouting channel through the grout inlet (10). The grout is simultaneously or sequentially lifted into the mold cavity from multiple outlets (11) through the grouting branch channel (9). Under the action of self-leveling, the grout gradually fills the lower skin plate forming surface (20), the core column (17) and rib plate (18) area and the upper skin plate forming surface (19). Air is discharged through the exhaust port (12), and excess grout overflows through the overflow port (13).

[0033] S4: Under the condition of maintaining negative pressure adsorption, the necessary external vibration or the self-compacting property of UHPC is used to complete the molding. After the UHPC reaches the initial solidification state, the vacuum source (14) is turned off, the negative pressure is released, and the curing is carried out in the conventional way. Finally, the mold is removed to obtain the one-time molded UHPC core column rib sandwich component.

[0034] 5. Parameter Control and Monitoring

[0035] In the preferred embodiment, the vacuum degree during the negative pressure adsorption stage is controlled within a certain range to resist the buoyancy and lateral pressure of the UHPC while avoiding crushing of the foam core material; the bottom pumping pressure is controlled in stages according to the component height and flow channel resistance to ensure stable rise of the slurry front and reduce bubble entrainment. The pumping flow rate and vacuum degree can be dynamically adjusted by monitoring the mold cavity status in real time through the observation window (22) or pressure sensor (23).

[0036] Compared with the prior art, the present invention has the following significant advantages:

[0037] 1. Achieve precise, non-penetrating positioning of lightweight core materials

[0038] By constructing a microporous negative pressure adsorption system on the mold forming surface, the foam core material (16) is firmly "adsorbed" in a predetermined position, avoiding the use of rigid connectors such as steel bars or bolts that penetrate the core material, eliminating the risk of thermal bridges and water seepage channels from the source, while improving the positional accuracy of the core material and the geometric stability of the mold cavity.

[0039] 2. Multi-point reverse casting at the bottom significantly improves density.

[0040] By adopting a bottom-up pumping and jacking method, combined with grouting branch channels (9) and grout outlets (11) that are optimized along the root of the core column, the root of the rib plate and the low-lying area of ​​the lower skin plate, the UHPC first fills the most difficult area to be poured, and the gas is discharged upwards, which significantly reduces the probability of voids and honeycomb pitting at the root of the core column and improves the density, compressive strength and fatigue performance of the key section.

[0041] 3. Cast in one continuous pour to avoid cold joints and weak interface layers.

[0042] The negative pressure adsorption ensures the stability of the core material and steel reinforcement skeleton, and the multi-point pressure grouting at the bottom enables the mold cavity to be filled quickly. The overall pouring can be completed within the allowable construction time without the need for layered or multi-stage pouring, thereby avoiding the formation of cold joints between the upper and lower skin plates and the core column ribs, and significantly improving the integrity and seismic performance of the components.

[0043] 4. Improve exhaust and vibration reduction requirements to reduce construction sensitivity.

[0044] Because of the reverse casting method combined with the top vent (12) and overflow port (13), the air is naturally discharged as the grout rises, reducing the reliance on traditional immersion vibration, and is especially suitable for complex sections of densely reinforced, multi-ribbed, multi-core columns; high-quality molding can be obtained under conditions of less external vibration or even relying solely on the self-compacting of UHPC.

[0045] 5. Facilitates standardized factory production and quality control.

[0046] This invention integrates a negative pressure adsorption system and a grouting channel system into a standard mold structure. The molding process can be controlled by adjusting the vacuum level, pumping pressure and flow rate, making it suitable for intensive and automated factory production and improving the stability and repeatability of "one-time casting of modular units".

[0047] 6. The technological approach is not a simple combination, but rather demonstrates outstanding creativity.

[0048] This invention is not simply a mechanical superposition of existing negative pressure molding or bottom pumping technologies. Instead, it addresses the specific needs of UHPC core column rib sandwich systems by collaboratively designing a microporous negative pressure adsorption zone layout, a multi-point arrangement of grouting branch channels, and a matching control of vacuum degree and pumping pressure. This forms a complete mold structure and reverse casting process scheme that are mutually dependent and complementary. It can solve the long-standing and unresolved problems of core material stability, cold seam control, and bottom dense molding in traditional processes, and has outstanding substantive features and significant progress. Attached Figure Description

[0049] To more clearly illustrate the technical solution of the present invention, the embodiments of the present invention will be further described below with reference to the accompanying drawings. The accompanying drawings are used to illustrate the principle of the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0050] Figure 1 This is a schematic diagram of the overall structure of a molding die for a UHPC core column rib plate according to the present invention. In the figure: 1—bottom mold; 2—side mold; 3—negative pressure chamber; 4—negative pressure pipeline; 5—ventilation micropores; 6—sealing rib; 7—elastic sealing strip; 8—main channel for grouting; 9—branch channel for grouting; 10—grout inlet; 11—grout outlet; 12—vent; 13—overflow outlet; 14—vacuum source; 15—concrete pump; 16—foam core material; 17—UHPC core column; 18—UHPC rib plate; 19—upper skin plate forming surface; 20—lower skin plate forming surface; 21—reinforcing steel skeleton; 24—mold frame support.

[0051] Figure 2 This is a partial cross-sectional schematic diagram of the negative pressure adsorption positioning system in the mold of the present invention, showing the arrangement of the negative pressure cavity and the air-permeable micropores between the foam core material and the bottom mold. In the figure: 1—bottom mold; 2—side mold; 3—negative pressure cavity; 4—negative pressure pipeline; 5—air-permeable micropores; 6—sealing rib; 7—elastic sealing strip; 14—vacuum source; 16—foam core material; 20—lower skin plate forming surface.

[0052] Figure 3 This is a schematic diagram of the planar structure of the bottom multi-point pressurized grouting channel system in the mold of the present invention, showing the arrangement of the main channel, multiple branch channels, and grout outlet. In the figure: 1—bottom mold; 8—main grouting channel; 9—branch grouting channel; 10—grout inlet; 11—grout outlet; 15—concrete pump; 17—UHPC core column (position shown); 18—UHPC rib (position shown); 20—lower skin forming surface.

[0053] Figure 4 This is a typical transverse cross-sectional schematic diagram of a UHPC core column and rib sandwich component manufactured using the mold and process of this invention. In the figure: 16—foam core material; 17—UHPC core column; 18—UHPC rib; 19—upper skin plate corresponding to the upper skin plate forming surface; 20—lower skin plate corresponding to the lower skin plate forming surface; 21—reinforcing steel skeleton.

[0054] Figure 5 This is a schematic diagram of the reverse casting process of the UHPC core column rib plate of the present invention. In the figure: A—Installation process of steel reinforcement skeleton and foam core material; B—Negative pressure adsorption positioning process; C—Bottom pumping grouting and venting process; D—Cure and demolding process; 22—Observation window; 23—Pressure sensor; 14—Vacuum source; 15—Concrete pump. Detailed Implementation

[0055] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that various modifications or equivalent substitutions can be made to the following embodiments without departing from the spirit and essence of the present invention, and all such modifications or equivalent substitutions should fall within the protection scope of the present invention.

[0056] Example 1: Molding mold structure for UHPC core column ribs

[0057] like Figure 1 , Figure 2 As shown, this embodiment provides a molding die for a UHPC core pillar rib plate, comprising:

[0058] Bottom mold (1): The bottom mold (1) is a steel structure integral welded component. Its upper surface is machined to form a lower skin plate forming surface (20). The flatness of the lower skin plate forming surface (20) is preferably controlled within 0.5 mm / m. The bottom mold (1) adopts a box-shaped or rib-plate reinforced structure inside to improve the overall rigidity and prevent deformation during casting.

[0059] Side mold (2): The side mold (2) surrounds the bottom mold (1) and is connected to the bottom mold (1) by bolts or a quick-locking mechanism. The inner side of the side mold (2) is machined with a forming surface that matches the contour of the component, which is used to define the position of the UHPC core column (17), UHPC rib plate (18) and the upper skin plate. The outer side of the side mold (2) is provided with a mold frame support (24) to ensure the dimensional stability of the overall mold.

[0060] Top mold or cover plate (25) (optional): For UHPC top skin plates that require strict control of the flatness of the upper surface or need to form a specific texture, a removable top mold or cover plate (25) can be set on the top of the side mold (2), with its lower surface corresponding to the top skin plate forming surface (19). The top mold (25) can be positioned with the side mold (2) by a limiting pin, which is convenient for installation and disassembly.

[0061] 1. Negative pressure adsorption positioning system

[0062] like Figure 1 , Figure 2 As shown, the bottom mold (1) and the side mold (2) are provided with negative pressure cavities (3) for negative pressure adsorption. The negative pressure cavities (3) can adopt one of the following structural forms or a combination thereof: a long strip-shaped negative pressure cavity (3) arranged longitudinally in the bottom mold, extending along the length of the component; a grid-shaped negative pressure cavity (3) distributed laterally, spaced along the width of the component; a local negative pressure cavity (3) separately set below or to the side of the expected arrangement area of ​​the core column (17) and the rib plate (18).

[0063] The negative pressure chamber (3) is connected to an external vacuum source (14) via a negative pressure pipeline (4). The negative pressure pipeline (4) can be made of metal or pressure-resistant hose, and a control valve is installed near the bottom mold (1) to adjust the vacuum level in zones or to open and close each zone sequentially according to the construction sequence. Preferably, independent negative pressure chambers (3) and negative pressure pipelines (4) are set for the core column zone, the rib zone, and the large-area flat plate zone respectively to achieve zoned adsorption.

[0064] A number of permeable micropores (5) are evenly distributed on the molding surfaces facing the mold cavity, namely the molding surface (20) of the lower skin plate and the inner wall of the side mold. The permeable micropores (5) are connected to the negative pressure cavity (3), and their diameter is preferably 0.05-1.0 mm, more preferably 0.1-0.5 mm; the hole spacing is preferably 5-50 mm, more preferably 10-30 mm. The opening of the permeable micropores (5) is basically flush with the surface of the mold cavity, and if necessary, it can be slightly lower than the molding surface by 0.1-0.3 mm to reduce the impact on demolding and the appearance quality of the component.

[0065] At the junction of the bottom mold (1) and the side mold (2), and in the area on the molding surface of the bottom mold (1) that contacts the foam core material (16), sealing ribs (6) and elastic sealing strips (7) are provided: the sealing ribs (6) are preferably raised ribs that are integrally welded or bolted to the bottom mold, and their height is generally 3 to 10 mm and their width is 10 to 30 mm; the elastic sealing strips (7) can be made of foamed rubber, silicone or wear-resistant polyurethane material, and are fixed to the sealing ribs (6) by bonding or embedding, and their hardness is preferably Shore A 30 to 70.

[0066] When installing the foam core material (16), the edge of the core material is pressed against the elastic sealing strip (7) to form a relatively closed adsorption chamber in the negative pressure cavity (3), which significantly improves the negative pressure retention effect and prevents the slurry from entering the negative pressure cavity (3) during pouring.

[0067] In some embodiments, a vacuum gauge and regulating valve may be installed on the negative pressure pipeline (4) to monitor and regulate the vacuum level in the negative pressure chamber (3) in real time, ensuring that the vacuum level is within the range of –0.02 to –0.08 MPa.

[0068] 2. Multi-point pressurized grouting channel system

[0069] like Figure 1 , Figure 3As shown, a main grouting channel (8) and several grouting branch channels (9) are set inside the bottom mold (1): The main grouting channel (8) is arranged along the length of the component and can be a circular or elliptical cross-section steel pipe, or a closed cavity directly formed in the steel plate of the bottom mold (1). One or both ends of the main channel (8) are provided with grout inlets (10), which are connected to the concrete pump (15) through hoses or pipelines; multiple grouting branch channels (9) branch from the main channel (8) and extend along the width of the component to below the forming surface (20) of the lower skin plate. Grout outlets (11) are set near the root of the UHPC core column (17), the root of the UHPC rib plate (18) and the low-lying area of ​​the lower skin plate; the grout outlets (11) are preferably vertically upward, or they can be inclined at a certain angle according to the structural arrangement, so that the grout can flow more easily into the lower part of the cavity of the core column (17) and the rib plate (18). The diameter of the slurry outlet (11) is determined according to the height of the component and the pumping pressure, and is generally 10 to 40 mm.

[0070] To ensure uniform rise of the slurry in the mold cavity, the slurry branch channels (9) can be arranged according to the principle of symmetrical arrangement. For example, they can be arranged symmetrically on both sides of the width direction of the component so that the slurry outlets (11) are equidistant from each other. For components with a larger width, an additional row of slurry outlets (11) can be added in the middle.

[0071] Vents (12) and overflow ports (13) are arranged at the upper edge of the side mold (2) or top mold (25). Vents (12) are usually set every 1 to 3 m along the length of the component, and overflow ports (13) are set near the highest point of the component. Metal filters or vent plugs can be installed inside the vents (12) to prevent excessive UHPC from flowing out, while allowing air to escape.

[0072] In situations where precise control of the pouring process is required, a transparent observation window (22) and a pressure sensor (23) can be installed near the vent (12) to facilitate observation of the rise height of the slurry and the pressure change inside the mold cavity.

[0073] Example 2: Reverse casting process for UHPC core column ribs

[0074] This embodiment combines Figure 4 , Figure 5 This describes the specific process steps for one-time molding of UHPC core column ribs using the above-mentioned mold.

[0075] 1. Procedure A: Installation of the reinforcing steel frame and foam core material (corresponding to...) Figure 5 (A)

[0076] Clean the bottom mold (1), side mold (2), main grouting channel (8), and grouting branch channel (9) to ensure that there is no residue or water accumulation inside; check whether the ventilated micropores (5) are unobstructed, and if there is blockage, use compressed air or fine needles to clear the holes. Tie the steel reinforcement skeleton (21) according to the design drawings, and fix the steel reinforcement skeleton (21) in the bottom mold (1) and side mold (2) by means of pads, brackets, etc., to ensure that the protective layer thickness meets the requirements. Cut and process the foam core material (16) according to the design dimensions. The foam core material (16) can be polystyrene, polyurethane, or other lightweight thermal insulation materials, with a density preferably of 15 to 80 kg / m³. Place the foam core material (16) in the lower skin plate forming surface (20) and the outline of the side mold (2) according to the design position, so that the surface of the core material fits the cavity of the bottom mold (1), side mold (2), core column, and rib plate. A reliable compression is formed between the foam core material (16) and the elastic sealing strip (7) to ensure that a closed adsorption cavity can be formed during subsequent vacuuming.

[0077] 2. Process B: Negative pressure adsorption positioning (corresponding to...) Figure 5 (B)

[0078] Close all slurry inlets (10), vents (12), and overflow outlets (13), open the valves on the negative pressure pipeline (4), and start the vacuum source (14). The vacuum source (14) evacuates the negative pressure chamber (3), and the negative pressure acts on the surface of the foam core material (16) through the permeable micropores (5), reliably adsorbing it onto the lower skin forming surface (20) and the side mold (2) forming surface. The negative pressure value is monitored by a vacuum gauge installed on the negative pressure pipeline (4), and the vacuum degree can be adjusted according to the core material strength and component height, generally controlled in the range of –0.02 to –0.08 MPa. When the core material size is large or the component height is high, the vacuum degree can be appropriately increased to resist the buoyancy generated by the weight of the UHPC and the pumping pressure. For the negative pressure chamber (3) arranged in zones, the negative pressure of the core column area can be started first as needed, and then the negative pressure of the large-area flat plate area can be started to avoid local premature adsorption causing installation and adjustment difficulties. After the negative pressure adsorption is completed, the position and flatness of the foam core material (16) are checked. If local warping or loose seams are found, local fine-tuning can be made, and then vacuuming can be performed again.

[0079] 3. Process C: Bottom pumping grouting and venting (corresponding to...) Figure 5 (C)

[0080] Mix UHPC according to the predetermined mix ratio, ensuring that the slump expansion, setting time, and viscosity meet the requirements for bottom pumping and self-leveling. Use it as soon as possible after mixing to avoid loss of workability. Connect the discharge port of the concrete pump (15) to the grout inlet (10) and check the sealing of all connections. Open the passages of the vent (12) and overflow port (13), and if necessary, remove the caps or loosen the regulating valves to connect the upper part of the mold cavity to the outside. Start the concrete pump (15) and supply grout to the main channel (8) of the grouting channel at a low initial pumping pressure (e.g., 0.1 to 0.2 MPa). UHPC enters the bottom area of ​​the mold cavity from the grout outlet (11) along the grouting branch channel (9), first filling the space around the bottom skin forming surface (20) and the roots of the core column (17) and rib plate (18). As the pouring height increases, the pumping pressure can be gradually increased to 0.2 to 0.6 MPa, and continuous or segmented pumping methods can be used depending on the height of the component. If the slurry rises too quickly at the observation window (22) or the pressure sensor (23) shows excessive internal pressure, the pump can be briefly paused or the pumping pressure reduced to avoid local overpressure. During the process of UHPC filling the mold cavity from bottom to top, air is discharged through the vent (12). When it is observed that slurry continuously overflows from the vent (12) and no longer carries obvious air bubbles, the corresponding vent (12) can be closed. When slurry begins to flow out of the overflow port (13), it indicates that the mold cavity is basically filled. Throughout the pumping process, the vacuum source (14) is kept working to maintain the stable adsorption of the foam core material (16) until the UHPC in the mold cavity is basically filled and the initial leveling is completed. Depending on the complexity of the component and the self-compacting properties of UHPC, one or a combination of the following methods can be selected to assist in molding: an external vibrator is installed on the outside of the bottom mold (1) or on the mold frame support (24) to apply low-amplitude high-frequency vibration to the entire mold to help air bubbles rise and be discharged; without damaging the stability of the core material, a slight tap or short-term low-frequency vibration is applied to a local area of ​​the component.

[0081] 4. Process D: Curing and demolding (corresponding to...) Figure 5 (D)

[0082] After pumping is completed, the UHPC is left to stand for a period of time under negative pressure adsorption until it reaches the initial setting state. The initial setting time is generally 2 to 6 hours depending on the mix ratio and ambient temperature. After the UHPC has initially set, the vacuum source (14) can be stopped and the negative pressure can be released slowly to avoid sudden changes in the stress on the core material or component surface caused by sudden changes in negative pressure. The component is cured according to the current standards or engineering requirements, and can be cured by film curing, steam curing or comprehensive curing. When steam curing, attention should be paid to the rate of temperature rise and fall to prevent early cracking due to excessive temperature gradient. When the strength of UHPC reaches the requirement for demolding (e.g., 50% or more of the design strength), the top mold or cover plate (25) (if any) is removed first, then the side molds (2) are removed in sequence, and finally the component together with the bottom mold (1) is lifted up as a whole and removed from the lower skin forming surface (20). After demolding, inspect the surface quality and internal density of the UHPC core column (17), UHPC rib plate (18), upper skin plate, and lower skin plate. If possible, use ultrasonic testing or core drilling to test the density and strength of key parts. The test results show that the components prepared by the process of this invention have almost no honeycomb pitting and visible voids at the root of the core column and rib plate, and the interface between the lower skin plate and the core column and rib plate is tight with no obvious cold seams.

[0083] Example 3: Variable configuration of structural layout and parameters

[0084] Based on the above embodiments, the present invention can also have various structural and parameter variations:

[0085] Variations in the arrangement of negative pressure chambers: When the component length is short (e.g., less than 3 m), only longitudinal or transverse negative pressure chambers (3) can be set in the bottom mold (1), and no negative pressure chamber is set in the side mold (2). The core material is stabilized by adsorption on the bottom surface. For components with a large number of core columns (17) and dense arrangement of ribs (18), a separate negative pressure chamber (3) can be set in the bottom mold (1) for each column of core columns to form a multi-channel independently controlled adsorption system so as to adjust the vacuum degree according to the local buoyancy.

[0086] Variations of the grouting channel system: For UHPC sandwich panels with low component height, it can be simplified to a single main channel (8) plus a small number of branch channels (9); for floor slab components with large span and width, one or more main channels (8) can be added in the middle of the component to allow grout to enter from both sides or multiple points, thus shortening the grout flow path.

[0087] Adjustment of process parameters: When using early-strength or fast-hardening UHPC mix proportions, the pumping speed can be appropriately increased to shorten the overall pouring time and ensure that the pouring is completed before initial setting; when the ambient temperature is low and the workability retention time is long, a lower pumping pressure and a gentler flow rate can be used to reduce air entrainment.

[0088] Expansion of applicable component types: In addition to typical flat UHPC core column ribs, the molds and processes of this invention can also be applied to: sandwich wall panels with irregular planes or folded edges; prefabricated house module floor slabs or roof panels with locally thickened ends or node areas; and UHPC sandwich components that require reserved holes or functional chambers for pipelines to be arranged in the slab.

[0089] In the above-mentioned different modifications, as long as the following are adopted simultaneously: a microporous negative pressure adsorption system arranged on the forming surface of the bottom mold (1) and / or side mold (2) is used to non-penetratingly position the foam core material (16); UHPC is cast from bottom to top through a multi-point pressurized grouting channel system at the bottom; and the problems of easy displacement of the core material, unavoidable cold seams, and difficulty in densification at the root of the core column and rib plate in the traditional process are solved, they should all be considered within the scope of protection of this invention.

[0090] As can be seen from the above embodiments, by integrating a microporous negative pressure adsorption system and a bottom multi-point reverse casting flow channel system in the mold, the present invention achieves stable and non-penetrating positioning of the core material of the UHPC core column rib sandwich component and one-time integral high-density molding, which significantly improves the component's seismic performance, thermal insulation performance and durability, and is suitable for factory-based, standardized mass production.

Claims

1. A one-time molding die for UHPC core pillar ribs, characterized in that, include: The system comprises: a bottom mold, the forming surface of which is used to form the lower contour of the bottom skin plate, core column, and rib plate; side molds surrounding the bottom mold; a negative pressure cavity arranged inside the bottom mold and / or side molds, the negative pressure cavity being connected to a vacuum source via a negative pressure pipeline, the forming surface of the negative pressure cavity having a number of breathable micropores evenly distributed for positioning the lightweight foam core material through negative pressure adsorption; and a grouting channel system located inside the bottom mold, the grouting channel system being connected to a concrete pump via a grout inlet, and having multiple grout outlets on the forming surface of the bottom mold corresponding to the root of the core column and / or the area of ​​the bottom skin plate; wherein, the micropores of the negative pressure cavity achieve stable fixation of the foam core material during the casting process, and the UHPC is pumped into the mold cavity from bottom to top through the grouting channel system.

2. The mold as described in claim 1, characterized in that: The negative pressure chamber is divided into sections along the core column and rib plate arrangement positions, and each section is connected to the vacuum source through an independent negative pressure branch to achieve zoned adsorption control of foam core material in different areas.

3. The mold as described in claim 1 or 2, characterized in that: The pore diameter of the breathable micropores is 0.05–1.0 mm, the pore spacing is 5–50 mm, and the micropore openings are flush with or slightly lower than the mold cavity surface to balance adsorption capacity and demolding properties.

4. The mold as described in any one of claims 1 to 3, characterized in that: The bottom mold forming surface is provided with sealing ribs and elastic sealing strips along the grouting channel. The sealing strips cooperate with the foam core material and the side mold to improve the sealing effect during negative pressure adsorption and bottom pumping.

5. The mold as described in any one of claims 1 to 4, characterized in that: The side mold and / or top mold are provided with vents and / or overflow ports that communicate with the mold cavity. The vents are provided with filters or air-permeable components to discharge air and excess slurry during bottom pumping.

6. The mold as described in any one of claims 1 to 5, characterized in that: The grouting channel system includes a main channel arranged along the length of the component and multiple branch channels connected to the main channel. Each branch channel leads to the grout outlet at the root of the core column, the root of the rib plate, and / or the low-lying part of the lower skin plate.

7. A casting process for preparing UHPC core column ribs using the mold described in any one of claims 1 to 6, characterized in that, include: S1. Place the steel reinforcement cage in the bottom and side molds, place the lightweight foam core material, and ensure that the foam core material is in contact with the forming surfaces of the bottom and side molds at the corresponding core column and rib positions; S2. Activate the vacuum source of the negative pressure chamber, and implement negative pressure adsorption and positioning of the foam core material through the air-permeable micropores to form a stable mold cavity; S3. Press the mixed UHPC into the grouting channel system through the bottom grouting inlet using a concrete pump, and lift it from bottom to top through each grout outlet to fill the mold cavity, while simultaneously expelling air and excess grout through the exhaust port; S4. While maintaining negative pressure adsorption, complete the vibration or self-compacting forming of the molded component. After the UHPC has initially set, release the negative pressure and cure it to the specified age. Then, remove the mold to obtain the UHPC core column and rib.

8. The casting process as described in claim 7, characterized in that: The vacuum level in the negative pressure adsorption stage of S2 is controlled at -0.02 to -0.08 MPa to resist the buoyancy of UHPC on the foam core material during the casting process, while avoiding excessive crushing of the foam core material.

9. The casting process as described in claim 7 or 8, characterized in that: The pumping pressure for bottom grouting of UHPC in S3 is controlled at 0.1 to 0.6 MPa, and segmented or continuous pumping is adopted according to the height of the component to reduce air bubble entrainment and ensure stable rise of the flow front.

10. The casting process according to any one of claims 7 to 9, characterized in that: During the S3 process, the rise height and internal pressure changes of the slurry in the mold cavity are monitored by a transparent observation window or pressure sensor located near the exhaust port, and the pumping flow rate and vacuum are dynamically adjusted accordingly.

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