Connecting structure of assembly type prefabricated column and construction technology of connecting structure

Abstract

The invention discloses a connecting structure of an assembly type prefabricated column and a construction technology thereof.The connecting structure is configured to be driven by a driving system, two-way path grouting is achieved through a multi-point grouting system, the connecting structure comprises a main steel pipe and an inserting steel pipe, and the main steel pipe is a semi-cylindrical solid steel pipe; a plurality of first grooves are downwards formed in the main steel pipe along the top end, the bottom of the main steel pipe is integrally connected with a disc-shaped connecting end, and a second groove is formed in the connecting end; the inserting steel pipe comprises an upper half connecting pipe and a lower half connecting pipe which are connected, the upper half connecting pipe is a solid cylinder, and a grouting hole is formed in the top side, close to the lower half connecting pipe, of the upper half connecting pipe. By designing a butt joint structure between the main steel pipe and the insertion steel pipe, high-precision butt joint of all connecting parts in the mounting process is ensured; meanwhile, a two-way grouting path is adopted, and sufficient grouting of the connecting joints is achieved through cooperation of the grouting holes and the sliding blocks.

Description

Technical Field

[0001] The present invention relates to the field of prefabricated columns, and specifically to a connection structure and construction technology for prefabricated columns. Background Art

[0002] The connection technology of precast columns is a crucial part in modern construction projects. Especially in prefabricated buildings, as key load-bearing components, the reliability of the connection of precast columns directly affects the stability and safety of the overall structure. With the continuous improvement of the requirements for construction period, construction accuracy, and structural safety in construction projects, the precast column connection technology faces multiple challenges.

[0003] The existing precast column connection technologies generally have the following several defects in practical applications, which limit their popularization and application in large-scale building construction:

[0004] Low construction efficiency: Traditional precast column connection technologies usually adopt hydraulic or screw-driven devices. Most of these methods rely on manual operations to complete docking and connection. The construction process is cumbersome and time-consuming. During the connection process, due to the need for multiple manual adjustments, the operation accuracy and coordination of construction workers will also affect the progress of the entire project, resulting in a significant decline in construction efficiency.

[0005] Poor positioning accuracy: In the existing connection structures, especially the docking problem between the slide rail and the slider is very prominent. Due to the traditional connection methods often relying on manual or mechanical rough alignment, the alignment accuracy between the slide rail and the slider is poor, which easily leads to incomplete biting or misalignment of the connection components, thus affecting the connection strength and even causing failures during the construction process. This error will not only increase the risk of rework but also affect the stability and safety of the entire precast column structure.

[0006] Insufficient grouting: The existing single grouting hole design is prone to problems such as uneven grouting and air holes. Especially during the grouting process, it is impossible to ensure that every gap in the connection part can be fully filled. This will lead to insufficient joint strength. Especially in complex stress environments, grouting defects will directly affect the bearing capacity and seismic performance of the connection part. The single grouting hole cannot effectively avoid the phenomenon of air bubbles or incomplete filling, resulting in the non-uniformity of the grouting layer and potential connection hidden dangers.

[0007] To solve the above problems, the existing publicly known technologies have proposed the following solutions, including:

[0008] 1) Publication No. CN107780530A discloses a connection structure and construction method for prefabricated columns. In this patent application, it includes prefabricated columns arranged on a precast base layer. At the position where the precast base layer is connected to the prefabricated column, several steel bars protruding from the precast base layer are provided. The steel bars penetrate the precast base layer. Precast holes for inserting the steel bars are formed on the prefabricated column. A sealing layer is provided at the position where the outer wall of the prefabricated column is connected to the precast base layer. A grouting hole communicating with the precast hole and several slurry outlet holes extending to the lower end of the precast hole are provided at the lower end of the prefabricated column. The grouting hole is located above the slurry outlet hole, and the slurry outlet hole is located above the sealing layer. A rubber plug for closing the grouting hole and the slurry outlet hole is provided on the prefabricated column.

[0009] 2) Publication No. CN117721954A discloses a connection structure and construction method for a cavity precast column joint. In this patent application, it includes a cavity precast column. Sixteen precast column steel bars are uniformly inserted and fixed inside the cavity precast column. The bottom ends of the precast column steel bars are located outside the bottom end of the cavity precast column. A joint connection mechanism, and the joint connection mechanism includes a steel bar connection cylinder. By designing and installing the joint connection mechanism, the skateboard is extruded by the precast column steel bar or the connecting steel bar, driving the clamping slider to tighten and bite the precast column steel bar or the connecting steel bar, so that the precast column steel bar or the connecting steel bar is fixed in the steel bar connection cylinder. Then, the tooth groove is used to prevent the precast column steel bar or the connecting steel bar from being pulled out of the steel bar connection cylinder, so that the precast column steel bar or the connecting steel bar can be simply inserted into the steel bar connection cylinder for connection, saving the connection steps, reducing the construction time, and improving the work efficiency.

[0010] 3) Publication No. CN109779013A discloses a connection method between prefabricated columns in a prefabricated concrete building. In this patent application, the connection between the column steel bars of the upper prefabricated column and the lower prefabricated column uses a connection sleeve. The connection sleeve is radially extruded to cause plastic deformation of the connection sleeve and interactively bite with the column steel bars to form a whole. The present invention can make the pouring efficiency of the column-to-column connection node higher, the quality controllability stronger, the process more simplified, easy to learn, effectively solve the problems of non-compaction of materials during grouting and material shrinkage, and greatly improve the pouring quality and stability of the node.

[0011] However, the above-mentioned existing technologies still have the following technical defects when applied.

[0012] Although grouting holes and slurry outlet holes are provided in Patent CN107780530A, the problem of air holes during the grouting process is not effectively solved. The design of the grouting holes may lead to uneven grouting, affecting the strength of the connection nodes. Especially under high load conditions, weaknesses may occur, resulting in insufficient structural stability. In CN117721954A, the connection is achieved through the engagement of a sliding plate and steel bars. However, since the fixation of the steel bars is realized by squeezing the sliding plate, problems such as inaccurate alignment of the sliding plate or incomplete engagement of the sliding blocks are likely to occur, thus affecting the connection strength. Especially in an environment with high vibration or deformation, the connection may fail. Additionally, in CN109779013A, there is still the problem of uneven grouting.

[0013] In summary, the existing technology requires a connection structure that can improve construction efficiency, accuracy, and connection strength, and ensure the connection. Summary of the Invention

[0014] The purpose of the present invention is to provide a connection structure and construction technology for prefabricated columns, which greatly improves the construction efficiency, accuracy, and quality of the connection of prefabricated columns through the cooperation of the connection structure and the multi-point grouting system, and ensures the strength and stability of the connection nodes.

[0015] To achieve the above purpose, the present invention provides the following technical solution: A connection structure for prefabricated columns, the connection structure is configured to be driven by a drive system and realize two-way path grouting through a multi-point grouting system. The connection structure includes a main steel pipe and an inserted steel pipe. The main steel pipe is a semi-cylindrical solid steel pipe. The main steel pipe is provided with a plurality of first grooves along the top downward. The bottom of the main steel pipe is integrally formed with a connecting end in the shape of a circular plate, and the connecting end is provided with a second groove; the inserted steel pipe includes an upper half connecting pipe and a lower half connecting pipe connected to each other. The upper half connecting pipe is a solid cylinder, and a grouting hole is provided on the top side of the upper half connecting pipe close to the lower half connecting pipe. By designing the docking structure between the main steel pipe and the inserted steel pipe, the high-precision docking of each connecting component during the installation process is ensured. This design can effectively avoid positioning deviations caused by manual operation errors, thereby ensuring the precise engagement of the connecting components.

[0016] Preferably, the lower half connecting pipe is a hollow steel pipe, and the end of the lower half connecting pipe is a semi-circular structure.

[0017] Preferably, cube-shaped protrusions are provided on the surface of the end of the lower half connecting pipe, and a plurality of sliding blocks are provided at intervals along the upper side section of the lower half connecting pipe.

[0018] Preferably, the surface of the slider is chrome-plated. A grouting through-hole is preset in the center of the slider. The slider is movably connected to the lower connecting pipe. The slider is a long sliding seat with a length of 90 mm, a width of 40 mm, a thickness of 30 mm, and a retractable length of 30 mm. The chrome-plated layer can significantly improve the surface hardness of the slider and enhance its wear resistance. During the contact and movement of the slider with the groove of the main steel pipe, it will be subject to large frictional force and wear. The chrome-plated surface can effectively reduce wear, extend the service life of the slider, and ensure the stability and reliability of the connection system during long-term use. In addition, the smooth surface of the chrome-plated layer helps to reduce the frictional force when the slider contacts the groove, thereby improving the sliding performance of the slider. The smooth movement of the slider can not only improve the construction efficiency but also reduce the resistance during the operation, making the slider move more stably and ensuring the precise docking of the connection structure.

[0019] Preferably, the first groove is a trapezoidal groove, and the second groove is a cubic groove and is used to fit with the cubic protrusion on the inserted steel pipe.

[0020] Preferably, the grouting hole is Φ35mm, and the grouting through-hole in the center of the slider is Φ20mm.

[0021] Preferably, the driving system is a gear-rack driving device. The gear-rack driving device can be configured outside the connection structure and extends into the grouting hole through a long rack to drive the slider to move and realize the ejection of the slider (ejection stroke: 30 mm).

[0022] The present invention also provides a construction process for the connection structure of the above-mentioned assembled precast column, including the steps:

[0023] Step 1: Embedded installation. The upper part of the inserted steel pipe is embedded in the upper precast column, and the main steel pipe is temporarily fixed on the lower precast column.

[0024] Step 2: Mechanical alignment. Lift the lower precast column, and fit the cubic protrusion at the end of the inserted steel pipe with the cubic groove on the main steel pipe.

[0025] Step 3: Configure the driving system. The driving system drives the rack to move linearly through the gear and sequentially ejects all the sliders into the grooves of the main steel pipe.

[0026] Step 4: Composite grouting. The reserved holes in the upper / lower precast columns form a two-way grouting path. Inject UHPC slurry with a fluidity ≥ 300 mm into the reserved holes of the upper / lower precast columns, and the grouting pressure is 0.3 - 0.5 MPa until the slurry overflows from the overflow hole of the lower precast column.

[0027] Step 5: Curing and forming. After curing at normal temperature for 24 hours, the compressive strength of the joint ≥ 120 MPa.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] The present invention greatly improves the construction efficiency, precision, and quality of the connection of prefabricated columns, and ensures the strength and stability of the connection nodes.

[0030] The specific technical effects are as follows:

[0031] Improve construction efficiency: The present invention realizes precise slider ejection through a gear-rack drive device, reduces the dependence on manual operation, and thus greatly improves the construction efficiency. Traditional connection methods require a large amount of manual participation, while this technical solution makes the connection process more automated through mechanical drive, significantly shortening the construction period.

[0032] Improve connection precision: By designing the docking structure between the main steel pipe and the inserted steel pipe, the present invention ensures the high-precision docking of each connection component during the installation process. This design can effectively avoid positioning deviations caused by manual operation errors, thereby ensuring the precise engagement of the connection components, improving the connection precision of the overall structure, and ensuring the stability and safety of the connection.

[0033] Ensure the adequacy and uniformity of grouting: The present invention adopts a two-way grouting path, and through the cooperation of grouting holes and sliders, full grouting of the connection nodes is achieved. The two-way grouting path can effectively avoid the problems of air holes or uneven grouting caused by a single grouting hole, ensure the complete filling of the grouting material, and improve the strength and durability of the nodes. This design not only improves the structural strength but also avoids connection weaknesses caused by grouting defects.

[0034] Enhance the strength and stability of the nodes: The present invention enhances the compressive, tensile, and seismic performance of the connection part through an innovative connection structure and a two-way grouting system. Due to the reasonable design of the grouting holes and slurry outlet holes and the precise ejection of the sliders, the strength of the connection nodes is greatly improved, enabling them to better withstand complex loads and external forces, ensuring the long-term stability and safety of the structure. After curing at room temperature for 24 hours, the compressive strength of the nodes can reach ≥120 MPa, significantly enhancing the compressive performance of the connection part of the precast column, ensuring the stability and load-bearing capacity of the nodes during use, and having better application prospects especially in buildings with high loads or high seismic requirements.

[0035] Simplify the construction process: The construction process of the present invention is simple and the steps are clear. Through simplified steps such as embedded installation, mechanical alignment, driving the slider out by the drive system, and composite grouting, the entire construction process becomes more efficient, reducing the cumbersome manual operations and unnecessary adjustments in traditional connection methods, and greatly improving the controllability and operability of the construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0037] Figure 2 It is a schematic structural diagram of the main steel pipe in the embodiment of the present invention;

[0038] Figure 3 It is a schematic structural diagram of the inserted steel pipe in the embodiment of the present invention;

[0039] Figure 4 It is a construction flow chart of the present invention.

[0040] In the figure:

[0041] 1. Main steel pipe; 101. First groove; 102. Connection end; 103. Second groove;

[0042] 2. Inserted steel pipe; 201. Upper half connecting pipe; 202. Lower half connecting pipe; 203. Grouting hole; 204. Cubic protrusion; 205. Slide block. Detailed implementation manners

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0044] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "vertical", "upper", "lower", "horizontal", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0045] In the description of the present invention, it should also be noted that unless otherwise clearly defined and limited, the terms "set", "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0046] Please refer to Figure 1 , the present invention provides a technical solution: a connection structure of a prefabricated precast column, and the connection structure is configured to be driven by a driving system and realize two-way path grouting through a multi-point grouting system. The connection structure includes a main steel pipe 1 and an inserted steel pipe 2.

[0047] Please refer to Figure 2, in this embodiment, the main steel pipe 1 is a semi-cylindrical solid steel pipe. A plurality of first grooves 101 are provided on the main steel pipe 1 extending downward from the top end. A connecting end 102 in the shape of a circular disc is integrally formed at the bottom of the main steel pipe 1, and a second groove 103 is provided on the connecting end 102.

[0048] Please refer to Figure 3 , the inserted steel pipe 2 includes an upper half connecting pipe 201 and a lower half connecting pipe 202 which are connected to each other. The upper half connecting pipe 201 is a solid cylinder. A grouting hole 203 is provided on the top side of the upper half connecting pipe 201 close to the lower half connecting pipe 202. The lower half connecting pipe 202 is a hollow steel pipe, and the end of the lower half connecting pipe 202 is a semi-circular structure. A cubic protrusion 204 is provided on the surface of the end of the lower half connecting pipe 202. A plurality of sliders 205 are provided on the lower half connecting pipe 202 at intervals along its upper side section.

[0049] In this embodiment, the surface of the slider 205 is chrome-plated. A grouting through-hole is preset at the center of the slider 205. The slider 205 is movably connected to the lower half connecting pipe 202. The slider 205 is a long sliding seat with a length of 90 mm, a width of 40 mm, a thickness of 30 mm, and a retractable length of 30 mm. The chrome-plated layer can significantly improve the surface hardness of the slider and enhance its wear resistance. During the process of the slider 205 coming into contact with and moving in the groove on the main steel pipe 1, it will be subject to relatively large friction and wear. The chrome-plated surface can effectively reduce wear, extend the service life of the slider, and ensure the stability and reliability of the connection system during long-term use. In addition, the smooth surface of the chrome-plated layer helps to reduce the friction when the slider 205 contacts the groove, thereby improving the sliding performance of the slider. The smooth movement of the slider can not only improve the construction efficiency, but also reduce the resistance during the operation process, making the slider move more stably and ensuring the precise docking of the connection structure.

[0050] In this embodiment, the first groove 101 is a trapezoidal groove, and the second groove 103 is a cubic groove and is used for fitting with the cubic protrusion 204 on the inserted steel pipe 2.

[0051] In this embodiment, the grouting hole 203 is Φ35 mm, and the grouting through-hole at the center of the slider 205 is Φ20 mm.

[0052] In this embodiment, the driving system is a gear-rack driving device. The gear-rack driving device can be configured outside the connection structure. It extends into the grouting hole 203 through a long rack and drives the slider 205 to move to realize the ejection of the slider 205 (the retractable stroke is 30 mm). By adopting an electric motor driving system, the electric motor driving system can be reused. This design reduces the cost of a single-node device by 40%, and significantly reduces the procurement and maintenance costs of the device.

[0053] In this embodiment, the three-dimensional grouting network formed by the central hole of the slider 205 and the reserved holes of the upper and lower precast columns is adopted. Through this design, the grouting path is smoother and more comprehensive, effectively improving the grouting density and meeting the density requirement of ≥99%. Compared with the traditional single grouting hole 203, the multi-stage grouting system of the present invention can better fill each gap at the connection part, avoiding problems such as air holes, cavities and uneven grouting, and greatly improving the structural strength and durability of the joint.

[0054] In this embodiment, through the above connection structure design, the installation time of a single connection node is greatly shortened, and the single-node connection time ≤15 minutes, which is 60% higher than the traditional process. The connection node of the present invention has extremely high mechanical properties, and the shear strength of the node ≥150MPa, far exceeding the strength requirements of traditional connection technologies. In addition, the seismic grade of the connection node reaches IX degree, and it can effectively withstand strong earthquakes and complex loads. This design enables the structure to maintain extremely high stability and safety under seismic regions or extreme load conditions, greatly improving the seismic performance and long-term use reliability of the building.

[0055] Please refer to Figure 4 , in combination with the above embodiments, the present invention also proposes a construction process for the connection structure of prefabricated precast columns, including the steps:

[0056] Step 1: Embedded installation. The upper half of the inserted steel pipe 2 is embedded in the upper precast column, and the main steel pipe 1 is temporarily fixed on the lower precast column (a temporary fixed design is adopted at the connection part of the main steel pipe 1 and the inserted steel pipe 2 in this connection structure, allowing a certain deviation correction during the construction process. This design facilitates quick alignment and adjustment during construction and avoids connection failure or construction delay caused by deviation).

[0057] Step 2: Mechanical alignment. Lift the lower precast column, and align the cube protrusion 204 at the end of the inserted steel pipe 2 with the cube groove on the main steel pipe 1. The lifting alignment is calibrated by a laser locator for the axes of the main steel pipe 1 and the inserted steel pipe 2.

[0058] Step 3: Configure the driving system. The driving system drives the rack to move linearly through the gear and sequentially pushes out all the sliders 205 to embed into the groove of the main steel pipe 1.

[0059] Step 4: Composite grouting. The reserved holes in the upper / lower precast columns form a two-way grouting path. Inject UHPC slurry with a fluidity ≥300mm into the reserved holes of the upper / lower precast columns, and the grouting pressure is 0.3 - 0.5MPa until the slurry overflows from the overflow hole of the lower precast column. Double-hole synchronous grouting is adopted during grouting, and the flow controller maintains the grouting speed at 5L / min.

[0060] Step 5: Curing and forming. After curing at room temperature for 24 hours, the compressive strength of the joint ≥ 120 MPa

[0061] This embodiment also provides a processing technology for the above connection structure, including the following: The main steel pipe 1 is processed with a laser to cut a groove (tolerance ±0.2 mm), the lower half of the inserted steel pipe 2 is welded with a guide rail, and the slider 205 is slidably connected to the guide rail (straightness ≤ 0.1 mm / m).

[0062] The assembled precast column connection structure of the above embodiment has significant technical advantages in improving connection accuracy, construction efficiency, grouting quality, and joint strength through advanced design and construction technologies. This technology is not only applicable to complex structures such as high-rise buildings and seismic engineering, but also has broad application prospects. Especially in the fields of industrialized and modular buildings and rapid construction, it can effectively improve the construction quality and efficiency of construction projects.

[0063] The standard parts used in the present invention can all be purchased from the market. The special-shaped parts can be customized according to the description in the specification and the drawings. The specific connection methods of each part all adopt conventional means such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts, and equipment all adopt conventional models in the prior art. In addition, the circuit connection adopts the conventional connection method in the prior art, which will not be elaborated here. The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0064] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. The meaning of "a plurality" is two or more unless otherwise specifically defined.

[0065] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A connection structure of assembled prefabricated columns, characterized in that: The connection structure is configured to be driven by a drive system and realize bidirectional grouting through a multi-point grouting system. The connection structure comprises a main steel pipe (1) and an inserted steel pipe (2). The main steel pipe (1) is a semi-cylindrical solid steel pipe. The main steel pipe (1) is provided with a plurality of first grooves (101) extending downward from the top. The bottom of the main steel pipe (1) is integrally formed with a connecting end (102) in the shape of a disc, and a second groove (103) is provided on the connecting end (102). The inserted steel pipe (2) comprises an upper connecting pipe (201) and a lower connecting pipe (202) connected to each other. The upper connecting pipe (201) is a solid cylinder. A grouting hole (203) is provided on the top side of the upper connecting pipe (201) close to the lower connecting pipe (202).

2. The connection structure of the assembled prefabricated columns according to claim 1 is characterized in that: The lower connecting pipe (202) is a hollow steel pipe, and the end of the lower connecting pipe (202) is a semicircular structure.

3. The connection structure of the assembled prefabricated columns according to claim 2 is characterized in that: The end surface of the lower connecting tube (202) is provided with a cubic protrusion (204), and a plurality of sliding blocks (205) are provided at intervals along the upper side section of the lower connecting tube (202).

4. The connection structure of the assembled prefabricated columns according to claim 3 is characterized in that: The surface of the slider (205) is chrome-plated, a grouting through hole is preset at the center of the slider (205), and the slider (205) is movably connected to the lower half connecting pipe (202).

5. The connection structure of the assembled prefabricated columns according to claim 1 is characterized in that: The first groove (101) is a trapezoidal groove, and the second groove (103) is a cubic groove and is used to be engaged with a cubic protrusion (204) inserted into the steel pipe (2).

6. The connection structure of an assembled prefabricated column according to claim 1, characterized in that: The grouting hole (203) is Φ35mm, and the grouting through hole at the center of the sliding block (205) is Φ20mm.

7. The connection structure of the assembled prefabricated columns according to claim 1 is characterized in that: The driving system is a rack and pinion driving device.

8. The construction process of the connection structure of assembled prefabricated columns according to any one of claims 1 to 7, characterized in that: Includes steps: Step 1: Pre-embedded installation, embedding the upper part of the inserted steel pipe (2) in the upper prefabricated column, and temporarily fixing the main steel pipe (1) on the lower prefabricated column; Step 2: Mechanical alignment, hoisting the lower prefabricated column, and inserting the cubic protrusion (204) at the end of the steel pipe (2) into the cubic groove on the main steel pipe (1); Step 3: configuring a driving system, the driving system drives the rack to move linearly through the gear, and pushes out all the sliders (205) in sequence to embed them into the grooves of the main steel pipe (1); Step 4: Composite grouting: the reserved holes of the upper / lower precast columns form a bidirectional grouting path, and UHPC slurry with a fluidity of ≥300mm is injected into the reserved holes of the upper / lower precast columns. The grouting pressure is 0.3-0.5MPa until the overflow hole of the lower precast column overflows with slurry; Step 5: After curing and molding at room temperature for 24 hours, the node compressive strength is ≥120MPa.

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