Detachable steel-concrete composite structure post-cast joint based on electrothermal alloy sleeve

Abstract

The invention discloses a detachable steel-concrete composite structure post-cast joint based on an electrothermal alloy sleeve. The detachable steel-concrete composite structure post-cast joint comprises a prefabricated concrete plate, a prefabricated concrete plate inner load-bearing steel bar, a detachable electrothermal alloy grouting sleeve, a high-performance detachable grouting material and high-performance detachable concrete. The connecting surfaces of the prefabricated concrete slabs on the two sides of the joint are aligned, a joint post-pouring area is reserved between the two side slabs, and the post-pouring area is filled with high-performance detachable concrete. Load-bearing steel bars in the precast concrete planks are connected through detachable electrothermal alloy grouting sleeves in a joint post-pouring area, the sleeves are filled with high-performance detachable grouting materials, and the detachable electrothermal alloy grouting sleeves are composed of high-strength bolt connecting assemblies, upper and lower semicircular positioning sleeves and high-temperature-resistant conductive modules. The problem that the connecting joint of the prefabricated concrete member is difficult to break is solved, a convenient and safe heating operation mode is provided, efficient disassembly is achieved, meanwhile, reusability is guaranteed, and remarkable economic benefits and environmental protection value are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of assembled structures, and in particular to a detachable steel-concrete composite structure post-cast node based on an electric heating alloy sleeve. Background Art

[0002] Concrete is the most widely used building material in the world. Its production process brings great pressure to the environment. Greenhouse gases produced by cement each year account for 9% of the world's total greenhouse gas emissions. The recycling of concrete components is considered to be one of the main ways to effectively reduce carbon emissions from concrete. At the same time, my country's annual concrete consumption ranks first in the world, and the annual emission of construction waste is as high as 1.55-2.4 billion tons. Therefore, the recycling and reuse of concrete components is crucial to the full implementation of the national conservation strategy and the acceleration of green transformation.

[0003] The key to the reuse of concrete components lies in the detachability of the structure. In existing prefabricated structures, precast concrete components often use post-cast concrete at the nodes, and the load-bearing steel bars in the components are butt-connected in the grouting sleeves, making the precast concrete components form an overall load-bearing structure of approximately equal strength, which is difficult to achieve secondary separation.

[0004] In order to separate structural components, researchers have proposed a variety of detachable node design schemes. For example, forced demolition methods such as blasting demolition, mechanical crushing demolition, high-pressure water jet cutting demolition and diamond demolition, or detachable grouting materials are used to achieve rapid dismantling of nodes. However, these schemes still have the following limitations: the existing detachable nodes still need to apply a large external force during dismantling, the crushing surface is single, the crushing accuracy is low, the reused components are easily damaged, and the disassembly process is complicated, making it difficult to achieve efficient operation; the existing detachable grouting materials and concrete have poor performance stability under high temperature or load, and it is difficult to meet the needs of complex engineering environments. Therefore, how to achieve rapid disassembly of precast concrete components, accurately separate and ensure the reusability of recycled components is a technical problem that needs to be solved urgently to achieve the recycling of concrete components. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention aims to provide a detachable post-cast node of a steel-concrete composite structure based on an electrothermal alloy sleeve to solve the problems in the above-mentioned background technology.

[0006] The present invention provides the following technical solutions: By pouring high-performance removable concrete in the post-casting area of ​​the node connected by the precast concrete slabs, and pre-embedding a multifunctional removable electric heating alloy grouting sleeve, and filling the sleeve with high-performance removable grouting material to connect the stressed steel bars in the precast concrete slabs, while ensuring the mechanical properties of the node connection, the removable electric heating alloy grouting sleeve can be connected to an external safe voltage to form a controllable node built-in steady-state heat source, so that the high-performance removable concrete in the post-casting area of ​​the node and the internal phase change material of the high-performance removable grouting material undergo solid-liquid phase transformation, thereby greatly reducing the strength, and can be gradually crushed from the outside to the inside by low mechanical load, so as to achieve lossless recovery of the stressed components and sleeve connectors.

[0007] The removable electrothermal alloy grouting sleeve comprises a friction type high-strength bolt, a high-strength nut, a bolt washer, an upper and lower semicircular positioning sleeve and a high temperature resistant conductive module. The friction type high-strength bolt is installed in the wing plate bolt hole of the upper and lower semicircular positioning sleeve, and the bolt pre-tightening force is applied through the high-strength nut and the bolt washer. The high temperature resistant conductive module is integrated at both ends of the removable grouting sleeve, and a stable current is passed into the removable electrothermal alloy grouting sleeve through symmetrical contacts evenly distributed on the sleeve cross section.

[0008] The friction type high-strength bolts, high-strength nuts, bolt washers, upper and lower semicircular positioning sleeves and high-temperature resistant conductive modules can be prefabricated in an integrated manner in a factory.

[0009] The electrical conductivity of the alloy material of the upper and lower semicircular positioning sleeves should be lower than 25MS / m, and the elastic modulus should not be lower than 200GPa.

[0010] The resistivity of the high temperature resistant conductive module material should not be higher than 2.7×10 -8 Ω·m.

[0011] The components of the high-performance demolishable concrete include cement, water, silica fume, fine aggregate, degradable organic fiber, high-efficiency water reducing agent and acrylic particles.

[0012] Optionally, the fine aggregate is quartz sand with a particle size range of 0.06-3 mm.

[0013] Optionally, the degradable organic fiber includes polypropylene fiber (PP), polyethylene fiber (PE), polyester fiber (PET), polyacrylonitrile fiber (PAN), and polylactic acid fiber (PLA).

[0014] Optionally, the degradable organic fiber has a length of 10-13 mm and a melting point range of 100-250°C.

[0015] Optionally, the acrylic particles have a particle size range of 2-3 mm, a solid-liquid phase transition temperature range of 100-250° C., and a linear thermal expansion coefficient of less than 7×10 -5 mm / mm·℃.

[0016] The high-performance removable grouting material components include cement, water, silica fume, ultra-fine quartz sand, expansion agent, high-efficiency water reducing agent, and acrylic powder.

[0017] Optionally, the ultrafine quartz sand has a particle size of less than 75 μm and a purity of greater than 99%, the expansion agent is a sulphoaluminate expansion agent, and the high-efficiency water reducer is a powdered polycarboxylic acid high-efficiency water reducer.

[0018] Optionally, the average particle size of the acrylic powder is 10-30 μm, and the solid-liquid phase transition temperature range is 100-250° C.

[0019] Optionally, after the detachable electric heating alloy sleeve is connected to an external power source, it generates heat evenly, and heats the high-performance removable concrete from the inside out by heat contact conduction. When the phase change temperature of the acrylic particles is reached, the acrylic particles undergo a solid-liquid two-phase transformation, and a large number of pores are generated in the concrete microstructure, and the concrete strength can be reduced by more than 85%.

[0020] Optionally, under the electric heating action of the removable electric heating alloy grouting sleeve, the high-strength bolt constraint of the removable electric heating alloy grouting sleeve is released, allowing the high-performance removable grouting material to expand and peel off toward the unconstrained side, and the unidirectional pull-out load of the steel bar can be reduced by more than 85%.

[0021] The beneficial effects of the present invention are as follows: The present invention provides a post-cast node of a detachable steel-concrete composite structure based on an electric heating alloy sleeve, which adopts a detachable electric heating alloy grouting sleeve to connect the stressed steel bars in the precast concrete component, and fills the post-cast area of ​​the node and the detachable electric heating alloy grouting sleeve with high-performance removable concrete and high-performance removable grouting material respectively. When the precast concrete component reaches a predetermined service life or has a change in use, maintenance and replacement, etc., the detachable electric heating alloy grouting sleeve is connected to an external power source to form a built-in steady-state heat source to heat the high-performance removable concrete and high-performance removable grouting material, so that the strength of both is significantly reduced and expansion and self-detachment occur, and the precast component can be quickly and accurately separated and non-destructively recycled under low external load. In addition, the built-in heating and removal device provided by the present invention is integrated and dual-purpose, and has both electric heat conduction and mechanical connection functions. Compared with the external heat source, it simplifies the device requirements, reduces energy dissipation, and ensures the strength of the steel bar connection, which greatly improves the feasibility of recycling the precast concrete component throughout its life cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of a detachable post-cast node of a steel-concrete composite structure based on an electrothermal alloy sleeve.

[0023] Figure 2This is a schematic diagram of the structure of a detachable electric heating alloy grouting sleeve (side view).

[0024] In the figure: 1 is a precast concrete slab; 2 is a stress-bearing steel bar in the precast concrete slab; 3 is a removable electric heating alloy grouting sleeve, 31 is a friction-type high-strength bolt, 32 is a high-strength nut, 33 is a bolt washer, 34 is an upper and lower semicircular positioning sleeve, 35 is a high-temperature resistant conductive module; 4 is a high-performance removable concrete; 5 is a high-performance removable grouting material. DETAILED DESCRIPTION

[0025] The specific implementation method of the technical solution provided by the present invention is further described in detail and clearly below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the technical content and features of the present invention in detail, and the dimensions and proportions of the accompanying drawings are simplified, which are only used to assist in explaining the embodiments of the present invention, and do not limit the present invention in any way.

[0026] See also Figure 1 This embodiment discloses a removable steel-concrete composite structure post-cast node based on an electrothermal alloy sleeve, including a precast concrete slab 1, stress-bearing steel bars 2 in the precast concrete slab, a removable electrothermal alloy grouting sleeve 3, high-performance removable concrete 4 and high-performance removable grouting material 5.

[0027] See also Figure 2 The removable electrothermal alloy grouting sleeve includes a friction-type high-strength bolt 31, a high-strength nut 32, a bolt washer 33, an upper and lower semicircular positioning sleeve 34 and a high-temperature resistant conductive module 35. The upper and lower semicircular positioning sleeves 34 are in the shape of a hoop, and bolt mounting holes are reserved on the wing plates on both sides, and the axes of the mounting holes coincide with each other. A grouting inlet and outlet are provided on the top of the upper semicircular positioning sleeve 34, and a positioning triangle is preset at the front and rear ends to improve the installation accuracy; the friction-type high-strength bolt 31 applies a pre-tightening force through the high-strength nut 32 and the bolt washer 33, so that the sleeve is tightly closed in the annular direction, and the upper and lower semicircular positioning sleeves 34 are constrained from sliding relative to each other longitudinally; the high-temperature resistant conductive module 35 is cylindrical, installed at the front and rear ends of the removable electrothermal alloy grouting sleeve 3, coincides with the central axis of the sleeve, and is connected to the sleeve cross section for multi-contact conduction. The contact points are symmetrical about the center of the circle, and the bundled wires are externally connected to an external power supply.

[0028] In this embodiment, the components of the high-performance removable concrete 4 include cement, water, silica fume, fine aggregate, degradable organic fiber, high-efficiency water reducing agent, and acrylic particles.

[0029] In this embodiment, the fine aggregate is quartz sand with a particle size range of 0.06-3 mm, the degradable organic fiber is a polypropylene fiber with a length of 12 mm, the high-efficiency water reducer is a polycarboxylate water reducer, the particle size of the acrylic (PMMA) particles is 2-3 mm, the melting point temperature is 200° C., and the volume content is 15%.

[0030] In this embodiment, the components of the high-performance removable grouting material 5 include cement, water, silica fume, ultrafine quartz sand, expansion agent, high-efficiency water reducing agent, and acrylic powder.

[0031] In this embodiment, the ultrafine quartz sand has a particle size of less than 75 μm and a purity of greater than 99%. The expansion agent is a sulphoaluminate expansion agent. The high-efficiency water reducer is a powdered polycarboxylate water reducer. The average particle size of the acrylic (PMMA) powder is 10-30 μm, the melting point is 200°C, and the volume content is 30%.

[0032] In this embodiment, the high-performance removable concrete 4 has a compressive strength of up to 71.6 MPa under normal service conditions, and the compressive strength can be reduced to below 8 MPa under continuous heating at 200°C.

[0033] In this embodiment, the high-performance removable grouting material 5 has a compressive strength of up to 100 MPa under normal service conditions, and the compressive strength can be reduced to below 12 MPa under continuous heating at 200°C.

[0034] See also Figure 1 and Figure 2 , a node post-casting area is reserved between the precast concrete slabs 1 on both sides, and a removable electric heating alloy grouting sleeve 3 is used in the node post-casting area to connect the stress-bearing steel bars 2 in the precast concrete slabs. The sleeve is filled with high-performance removable grouting material 5 to establish steel bar bonding. High-performance removable concrete 4 is poured in the node post-casting area to make the precast concrete slabs 1 on both sides form an integral component. The removable electric heating alloy grouting sleeve 3 is connected to an external safe voltage through a high-temperature resistant conductive module 35, so that the high-performance removable concrete 4 is heated from the inside to the outside. The internal acrylic particles undergo solid-liquid two-phase transformation at the target heating temperature, generating a large number of microscopic pores, which significantly reduce the macroscopic strength of the concrete and can be crushed and removed by low mechanical load. After the external high-performance removable concrete 4 is removed, the detachable electrothermal alloy grouting sleeve 3 releases the circumferential constraint of the friction-type high-strength bolts 31, and the high-performance removable grouting material 5 is allowed to expand and fall off to the unconstrained side under the action of continuous heating. The stressed steel bars 2 in the precast concrete slab can be pulled out by a low tensile load, thereby completely recovering the precast concrete slabs 1 on both sides, the stressed steel bars 2 in the precast concrete slab and the detachable electrothermal alloy grouting sleeve 3.

[0035] The above specific embodiments demonstrate the core principles, main features and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the specific details of the above embodiments, but can be implemented in other specific forms without violating the spirit and basic features of the present invention. Therefore, these embodiments should be regarded as exemplary rather than restrictive. The scope of the present invention is defined by the attached claims rather than the above description. Any equivalent changes, modifications, substitutions or improvements to the embodiments should be included in the scope of the present invention.

Claims

1. A detachable post-cast node of steel-concrete composite structure based on an electrothermal alloy sleeve, characterized in that: The invention comprises a precast concrete slab (1), stress-bearing steel bars (2) in the precast concrete slab, a detachable electric heating alloy grouting sleeve (3), high-performance removable concrete (4) and high-performance removable grouting material (5); the connection surfaces of the precast concrete slabs (1) on both sides of the node are aligned, and a node post-casting area is reserved between the slabs; the stress-bearing steel bars (2) in the precast concrete slab are connected by means of the detachable electric heating alloy grouting sleeve (3) and the high-performance removable grouting material (5); the high-performance removable concrete (4) is filled in the node post-casting area, so that the precast concrete slabs (1) on both sides form Integral component; under the electric heating action of the removable electric heating alloy sleeve (3), the high-performance removable concrete (4) is gradually heated from the inside to the outside through heat contact conduction, and can be broken by a low impact load after reaching the target temperature; after the high-performance removable concrete (4) in the post-casting area of ​​the node is broken, the removable electric heating alloy grouting sleeve (3) releases the annular constraint on the internal high-performance removable grouting material (5), and under the action of electric heating, the high-performance removable grouting material (5) expands and peels off, and the stressed steel bars (2) in the precast concrete slab can be pulled out under a low tensile load.

2. A detachable post-cast node of steel-concrete composite structure based on an electrothermal alloy sleeve according to claim 1, characterized in that: The detachable electrothermal alloy grouting sleeve (3) comprises a friction-type high-strength bolt (31), a high-strength nut (32), a bolt washer (33), an upper and lower semicircular positioning sleeve (34) and a high-temperature resistant conductive module (35); the upper and lower semicircular positioning sleeves (34) are in the shape of a hoop, with bolt mounting holes reserved on the wing plates on both sides, a grouting inlet and outlet opening provided on the top of the upper semicircular positioning sleeve, and positioning triangles are preset at the front and rear ends of the upper and lower semicircular positioning sleeves so that the sleeves are longitudinally aligned; the friction-type high-strength bolt (31) is installed in the wing plate mounting hole, and a pre-tightening force is applied by the high-strength nut (32) and the bolt washer (33) so that the sleeves are tightly closed in the circumferential direction, thereby restricting the upper and lower semicircular positioning sleeves (34) from relative longitudinal sliding; the high-temperature resistant conductive module (35) is cylindrical, installed at the front and rear ends of the detachable electrothermal alloy grouting sleeve, with the central axis coinciding, and connected to the sleeve cross section through multiple contacts for electrical conduction, the contact points are symmetrical about the center of the circle, and the wires are externally connected to an external power supply.

3. The detachable post-cast node of steel-concrete composite structure based on electric heating alloy sleeve according to claim 1 is characterized in that: The components of the high-performance removable grouting material (5) include cement, water, silica fume, ultrafine quartz sand, expansion agent, high-efficiency water reducing agent, and acrylic powder.

4. The detachable post-cast node of steel-concrete composite structure based on electric heating alloy sleeve according to claim 3 is characterized in that: The ultrafine quartz sand has a particle size of less than 75 μm and a purity of greater than 99%; the expansion agent is a sulphoaluminate expansion agent; the acrylic powder has an average particle size of 10-30 μm, and a solid-liquid conversion phase transition temperature range of 100-250°C.

5. According to the high-performance removable post-cast node of steel-concrete composite structure based on phase change material in claim 1, it is characterized in that: The components of the high-performance removable concrete (4) include cement, water, silica fume, fine aggregate, degradable organic fiber, high-efficiency water reducing agent, and acrylic particles.

6. The detachable post-cast node of steel-concrete composite structure based on electric heating alloy sleeve according to claim 5 is characterized in that: The fine aggregate is quartz sand with a particle size range of 0.06-3mm; the degradable organic fiber is polypropylene fiber with a length of 10-13mm and a melting point range of 100-250°C; the acrylic particle size range is 2-3mm, and the solid-liquid conversion phase change temperature range is 100-250°C.

7. The detachable post-cast node of steel-concrete composite structure based on electric heating alloy sleeve according to claim 1 is characterized in that: Under the electric heating action of the removable electric heating alloy grouting sleeve (3), the acrylic material inside the high-performance removable concrete (4) and the high-performance removable grouting material (5) undergoes a solid-liquid two-phase transformation, so that the strength of the high-performance removable concrete (4) and the high-performance removable grouting material (5) is reduced by more than 85%, and the high-performance removable concrete (4) and the high-performance removable grouting material (5) can be crushed and removed by a low external load.

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