A restrained recycled concrete structure and a method of manufacture

Abstract

The application discloses a constrained recycled concrete structure and a preparation method thereof. The constrained recycled concrete structure comprises a constraint cylinder, has a constraint cavity surrounded by an inner wall, and is provided with a constraint structure on the inner wall. A concrete structure body is cast in the constraint cavity. The concrete structure body is provided with an electro-osmotic water drainage device for draining water, and is distributed with spiral pipe-shaped steel fibers. By adopting performance improvement measures such as mixing spiral pipe-shaped steel fibers, electro-osmotic intelligent water drainage, structural stress constraint, MgO-dry ice water stability treatment and the like in the preparation of the recycled concrete, the comprehensive performance of the recycled concrete can be significantly improved, and the recycled concrete can be used as a building material for important and key stress members in a structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete, in particular to a constrained recycled concrete structure and a preparation method thereof. BACKGROUND

[0002] The application of recycled concrete has great significance for the sustainable development of low-carbon economy. Due to the poor properties of recycled concrete such as low strength, brittleness, high porosity, strong water permeability, and low durability, it is currently mainly used as a building material for filling, separation, or non-main load-bearing components. When it is applied to important load-bearing components such as beams, columns, and foundations, the above-mentioned poor properties need to be improved.

[0003] Currently, the main measures for improving recycled concrete include adding mineral powder admixtures, additives, or steel fibers, activating recycled aggregates, and increasing the constraint stress. The above measures improve the performance of recycled concrete to some extent and expand its application range, but the improvement of brittleness, water stability, and durability is not obvious. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a constrained recycled concrete structure that can significantly improve the comprehensive performance of recycled concrete and can be used as a building material for important and critical load-bearing components in structures.

[0005] The present application also proposes a preparation method of the above-mentioned constrained recycled concrete structure.

[0006] According to the constrained recycled concrete structure of the first aspect of the present application, the constrained recycled concrete structure comprises:

[0007] a constraint cylinder having a constraint cavity surrounded by an inner wall;

[0008] a constraint structure arranged on the inner wall;

[0009] a concrete structure body cast in the constraint cavity, wherein the concrete structure body further comprises an electro-osmotic hydrophobic device for draining water, and the concrete structure body is distributed with spiral pipe-shaped steel fibers.

[0010] According to the constrained recycled concrete structure of the first aspect of the present application, the spiral pipe-shaped steel fibers are prepared by processing steel fibers with a diameter of 1-1.5 mm into spring-shaped.

[0011] According to the constrained recycled concrete structure of the first aspect of the present application, the length L of the spiral pipe-shaped steel fibers is 3-5 cm, the spiral diameter d is 3-6 mm, and the spiral pitch h is 3-5 mm.

[0012] According to the first aspect of the application, the constrained recycled concrete structure comprises an electro-osmotic hydrophobic device, which comprises a controller, an electro-osmotic anode, an electro-osmotic cathode and a humidity sensor. The electro-osmotic anode and the electro-osmotic cathode are oppositely arranged. The humidity sensor is used to monitor the water content in the concrete structure body. The controller is adapted to receive information from the humidity sensor and control the electro-osmotic anode and the electro-osmotic cathode to generate an electric field between the electro-osmotic anode and the electro-osmotic cathode, which is suitable for driving the movement of water molecules. The electro-osmotic cathode is surrounded by a water-permeable geotextile material, which is suitable for draining water.

[0013] According to the first aspect of the application, the constrained recycled concrete structure comprises a plurality of constraint structures, which are arranged in multiple layers along the inner wall. The constraint structures in each layer are spaced from each other. The constraint structures in adjacent layers are arranged in a circumferential direction.

[0014] According to the first aspect of the application, the constraint structure comprises at least one of a constraint ring, a constraint block or a constraint nail.

[0015] According to the first aspect of the application, when the constraint structure comprises at least one of a constraint block or a constraint nail, the constraint structures in each layer are the same in structure, or the constraint structures in at least two layers are different in structure.

[0016] The constraint cylinder is a cylindrical steel cylinder or a rectangular steel cylinder.

[0017] According to the second aspect of the application, the preparation method of the constrained recycled concrete structure comprises the following steps:

[0018] Preparation of recycled concrete using recycled aggregate, cement and sand;

[0019] Mixing 0.5-1.5% of the spiral pipe-shaped steel fiber in the concrete quality in the recycled concrete and stirring uniformly;

[0020] Arranging the constraint structure on the inner wall of the constraint cylinder and burying the electro-osmotic hydrophobic device;

[0021] Pouring the recycled concrete into the constraint cylinder to form a constrained recycled concrete structure.

[0022] According to the second aspect of the application, the preparation method of the constrained recycled concrete structure comprises mixing an appropriate amount of expansion agent in the recycled concrete, wherein the amount of expansion agent is controlled according to the following calculation of the volume expansion rate θ:

[0023]

[0024] wherein, θ is the volume expansion rate of the recycled concrete after mixing with the expansive agent, θ0 is the volume shrinkage rate of the recycled concrete without mixing with the expansive agent; E1 is the elastic modulus of the recycled concrete, μ1 is the Poisson's ratio of the recycled concrete; E, D, t are the elastic modulus of the constraint cylinder, the diameter or the long side of the rectangle of the constraint cylinder, and the thickness of the cylinder wall, respectively; σ f is the design constraint stress value of the concrete, σ f is calculated in the following manner:

[0025]

[0026] wherein, σ s is the yield stress of the constraint cylinder, K is the stress reserve coefficient, which is 4-6, that is, when the volume expansion rate θ is mixed with the expansive agent in the concrete, the maximum expansion circumferential stress in the constraint cylinder is 1 / K (i.e. σ s / K) of the yield stress of the constraint cylinder; α is the constraint cylinder cross-section shape coefficient, which is 1 for a circular cross-section and 0.5-0.7 for a rectangular cross-section.

[0027] According to the preparation method of the constrained recycled concrete structure according to the second aspect of the present application, when the recycled concrete is prepared, 10-15% of the cement quality of MgO mineral powder and 30-50% of the MgO mineral powder quality of dry ice particles are mixed in the preparation of the recycled concrete, and the particle size of the dry ice particles is less than 1 cm;

[0028] In the preparation process, the MgO mineral powder and the dry ice particles are fully stirred and uniformly placed in a closed state for 45-60 minutes to make the CO2 after the dry ice gasification react with the MgO; then the excess CO2 gas is discharged by stirring for 5-10 minutes with a vibrating rod, and finally the recycled concrete is fully stirred and then poured into the member.

[0029] The present application has at least the following beneficial effects: by using the performance improvement measures such as mixing with spiral pipe-shaped steel fibers, electro-osmotic intelligent hydrophobic, structural stress constraint, MgO-dry ice water stability treatment, etc. in the preparation of the recycled concrete, the comprehensive performance of the recycled concrete can be significantly improved, and the recycled concrete can be used as the building material for important and key stressed members in the structure.

[0030] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0031] The present application will be further described below in conjunction with the drawings and examples;

[0032] Figure 1 is the structure sectional view of the present application embodiment;

[0033] Figure 2 isFigure 1 Cross-sectional view of A-A;

[0034] Figure 3 Structure cross-sectional view of the application embodiment provided with electro-osmotic cathode and water-permeable geotextile;

[0035] Figure 4 Structure schematic view of the application embodiment provided with helical pipe-shaped steel fiber;

[0036] Figure 5 Structure schematic view of the application embodiment provided with cylindrical steel cylinder as constraint cylinder;

[0037] Figure 6 Structure schematic view of the application embodiment provided with rectangular steel cylinder as constraint cylinder.

[0038] Reference signs:

[0039] 100, constraint cylinder; 200, constraint structure member; 300, concrete structure body; 400, helical pipe-shaped steel fiber; 510, electro-osmotic cathode; 520, electro-osmotic anode; 530, humidity sensor; 540, water-permeable geotextile; 550, controller. DETAILED DESCRIPTION

[0040] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary, only for explaining the present application, and cannot be understood as a limitation to the present application.

[0041] In the description of the present application, it is understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, only for the purpose of describing the present application and simplifying the description, and does not indicate or imply that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation to the present application.

[0042] In the description of the present application, the meaning of several is one or more, the meaning of multiple is at least two, greater than, less than, more than, etc. is not included in the number, above, below, etc. is understood to include the number. If it is described as first, second, only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the order of indicated technical features.

[0043] In the description of the present application, the words such as arrangement, installation, connection and the like should be understood in a broad sense unless otherwise explicitly limited, and the skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solutions.

[0044] It can be understood that the recycled concrete is prepared by using recycled aggregate, cement, sand and other materials. The recycled aggregate is selected by mechanically crushing, sieving and washing the waste concrete with a strength of C20 or above.

[0045] With reference to Figures 1 to 6 The constraint recycled concrete structure of the first aspect embodiment of the present application comprises.

[0046] The constraint cylinder 100 has a constraint cavity surrounded by an inner wall;

[0047] The constraint structure 200 is arranged on the inner wall;

[0048] The concrete structure body 300 is cast in the constraint cavity. The concrete structure body 300 further comprises an electro-osmotic hydrophobic device for draining water, and the concrete structure body 300 is distributed with a spiral pipe-shaped steel fiber 400.

[0049] It can be understood that the recycled concrete prepared by using recycled aggregate has low strength and high brittleness due to the low surface activity of the recycled aggregate. The main role of mixing steel fiber in the recycled concrete is to improve the strength of the recycled concrete. In the related art, the anchoring force between the “linear” steel fiber and the concrete is often insufficient, and the steel fiber is often pulled out during deformation; the anchoring force between the “special-shaped” steel fiber and the concrete is large enough, but the deformation model of the concrete matrix and the deformation model of the steel fiber are greatly different (the ratio of the two is about 1 / 10), and the deformation of the two is not coordinated, which causes micro-cracks in the concrete matrix. Therefore, the method of mixing “linear” or “special-shaped” steel fiber has limited effect on improving the plasticity of the recycled concrete, and the steel fiber reinforced concrete load-bearing member will still have “brittle failure” and insufficient safety.

[0050] In the present application, the spiral pipe-shaped steel fiber 400 is mixed in the recycled concrete. Compared with the “linear” or “special-shaped” (such as end hook type, milling type, shearing type, etc.) steel fiber, the spiral pipe-shaped steel fiber 400 can be embedded more firmly in the concrete matrix and can stretch and contract like a spring to adapt to the deformation of the concrete matrix and avoid micro-cracks, thereby improving the strength of the recycled concrete and effectively improving the plasticity of the recycled concrete, preventing the member from having “brittle failure” and improving the safety.

[0051] In some embodiments of the present application, with specific reference to Figure 4The helical pipe-shaped steel fiber 400 is made of steel fiber with a diameter of 1-1.5 mm and is processed into a spring shape. Preferably, the length L of the helical pipe-shaped steel fiber 400 is 3-5 cm, the helical diameter d is 3-6 mm, and the helical pitch h is 3-5 mm. It can be understood that the helical pipe-shaped steel fiber 400 is randomly distributed in the concrete, and based on the above targeted parameter design, the mortar can be filled in the helical pipe, and after the helical pipe-shaped steel fiber 400 is mixed, the recycled concrete can simultaneously improve its strength and plasticity performance, and avoid the "brittle failure" of the recycled concrete member.

[0052] In some embodiments of the present application, with particular reference to Figure 5 and Figure 6 , the electro-osmotic hydrophobic device includes a controller 550, an electro-osmotic anode 520, an electro-osmotic cathode 510, and a humidity sensor 530, the electro-osmotic anode 520 and the electro-osmotic cathode 510 are oppositely arranged, the humidity sensor 530 is used to monitor the water content in the concrete structure body 300, the controller 550 is adapted to receive information of the humidity sensor 530 and control the electro-osmotic anode 520 and the electro-osmotic cathode 510, so as to generate an electric field between the electro-osmotic anode 520 and the electro-osmotic cathode 510 suitable for driving water molecules to move, and with particular reference to Figure 3 , the electro-osmotic cathode 510 is surrounded by a water-permeable geotextile 540, and the water-permeable geotextile 540 is adapted to discharge water.

[0053] It can be understood that in a wet or water environment, the components are easily eroded by chloride ions, water molecules and the like, and for important force components, an electro-osmotic intelligent hydrophobic technology can be used to improve the durability. The electro-osmotic anode 520 and the electro-osmotic cathode 510 and the humidity sensor 530 are embedded in the component; the electro-osmotic anode 520 and the electro-osmotic cathode 510 are connected to the positive and negative electrodes of the controller 550 respectively; the humidity sensor 530 monitors the water content in the concrete in real time; the switching power supply is controlled by the humidity of the concrete, and outputs a direct current voltage of 12-36 volts, when the humidity in the concrete is greater than or less than the critical value (the critical value can be set in the range of 40%-60%), the power supply is automatically turned on or off. The electro-osmotic cathode 510 and the electro-osmotic anode 520 are made of φ=1.5-2.0cm steel bars or aluminum strips, and the electro-osmotic cathode 510 is wrapped with a water-permeable geotextile material 540 with a thickness of 1-1.5cm; a small volume sensor is used for humidity sensing; the controller 550 is composed of a central processing chip (MCU), a data acquisition chip and a silicon controlled switch chip, the humidity data collected is transmitted to the MCU for processing, and the silicon controlled switch is controlled. When the power is turned on, the electric field generated between the electro-osmotic cathode 510 and the electro-osmotic anode 520 will drive the water molecules in the concrete to the cathode and discharge from the water-permeable geotextile material 540, intelligently draining the water in the concrete and reducing the diffusion of chloride ions and other erosion substances; at the same time, the adsorption of the electro-osmotic anode 520 to chloride ions and other erosion substances reduces the erosion of the concrete matrix and the steel bars, effectively improving the durability of the structure. For each important force component in the structural system, in some embodiments, the control of each electro-osmotic anode 520 and electro-osmotic cathode 510 can be connected to one controller 550, and unified electro-osmotic intelligent hydrophobic management is implemented.

[0054] In some embodiments of the present application, with particular reference to Figure 1 and Figure 2 , a plurality of constraint structures 200 are provided, and the constraint structures 200 are arranged at intervals along the inner wall and form multiple layers, the constraint structures 200 in each layer are spaced above and below each other, and the constraint structures 200 in adjacent layers are arranged in a circumferential direction. Further, the constraint structure 200 includes at least one of a constraint ring, a constraint block or a constraint nail, wherein when the constraint structure 200 includes at least one of a constraint block or a constraint nail, the structures of the constraint structures 200 in each layer are the same, or the structures of at least two constraint structures 200 in at least one layer are different. Preferably, the constraint cylinder 100 is a cylindrical steel cylinder or a rectangular steel cylinder.

[0055] It can be understood that for important key components such as structural girder and large load column, the construction stress constraint method of the constraint cylinder 100-regenerated concrete is used to improve the load bearing capacity and safety reliability of the component. The regenerated concrete is poured into the constraint cylinder 100 with a constraint structure, and the constraint cylinder 100 is a circular or rectangular steel cylinder. The constraint rings, constraint blocks or constraint nails and other constraint structures are arranged on the inner wall of the steel cylinder at certain intervals. The constraint structures such as constraint rings, constraint blocks and constraint nails in the steel cylinder can be arranged separately or in combination, such as constraint ring-block combination, constraint ring-pin combination, constraint block-pin combination and other constraint structures. When the constraint block and the constraint pin structure are used, the upper and lower constraint blocks / pins are arranged in a circumferential staggered manner, so that the distribution of the constraint stress with a constraint effect is more uniform. At the same time, a proper amount of expanding agent is mixed in the concrete to eliminate the relatively large shrinkage of the regenerated concrete and generate appropriate constraint prestress. The calculation of the amount of the expanding agent will be further described in subsequent embodiments.

[0056] It can be understood that the components in the related art do not have corresponding structures that can generate axial constraint stress. The concrete in the cylinder is only subjected to horizontal radial and circumferential constraint stress. When subjected to bending moment, the steel cylinder and the concrete interface are prone to mutual sliding, so it can only be used as a column that mainly bears axial pressure load.

[0057] In the present application, the constraint structures that generate axial constraint stress are arranged on the inner wall of the steel cylinder at certain intervals, so that the concrete is subjected to three-dimensional constraint stress in the radial direction, the circumferential direction (constrained by the constraint cylinder 100) and the axial direction (generated by the constraint structure). The concrete is forced to deform coordinately with the constraint cylinder 100, and can bear a larger bending stress. At the same time, a proper amount of expanding agent is mixed in the concrete according to theoretical calculation, so that the three-dimensional constraint stress is more uniform, the deformation of the constraint cylinder 100 and the concrete is more coordinated, and the bending resistance is further improved. Therefore, the above steel cylinder-construction stress constraint regenerated concrete component can be used as a column and a main girder that mainly bears bending moment.

[0058] Referring to Figures 1 to 6 The preparation method of the constraint regenerated concrete structure of the second aspect embodiment of the present application can be the preparation method of the constraint regenerated concrete structure of the first aspect embodiment of the present application. The preparation method of the constraint regenerated concrete structure comprises the following steps:

[0059] Preparation of regenerated concrete using regenerated aggregate, cement and sand;

[0060] Mixing 0.5-1.5% of the spiral pipe-shaped steel fiber 400 in the concrete and stirring uniformly;

[0061] Setting the constraint structure 200 on the inner wall of the constraint cylinder 100 and embedding the electro-osmotic hydrophobic device;

[0062] The recycled concrete is cast in the constraint cylinder 100 and a constraint recycled concrete structure is formed.

[0063] In some embodiments of the present application, an appropriate amount of expansive agent is incorporated in the recycled concrete, wherein the amount of the expansive agent is controlled according to the volume expansion rate θ calculated as follows:

[0064]

[0065] wherein θ is the volume expansion rate of the recycled concrete after incorporation of the expansive agent, θ0 is the volume shrinkage rate of the recycled concrete without incorporation of the expansive agent; E1 is the elastic modulus of the recycled concrete, μ1 is the Poisson's ratio of the recycled concrete; E, D, t are the elastic modulus of the constraint cylinder 100, the diameter or the long side of the rectangle of the constraint cylinder 100 and the thickness of the cylinder wall, respectively; σ f is the design constraint stress value of the concrete, σ f is calculated as follows:

[0066]

[0067] wherein σ s is the yield stress of the constraint cylinder 100, K is the stress reserve coefficient, which is 4-6, i.e. when the volume expansion rate θ is generated in the concrete after incorporation of the expansive agent, the maximum expansion circumferential stress in the constraint cylinder 100 is 1 / K (i.e. σ s / K) of the yield stress of the constraint cylinder 100; α is the cross-sectional shape coefficient of the constraint cylinder 100, which is 1 for a circular cross-section and 0.5-0.7 for a rectangular cross-section.

[0068] Further, the theoretical derivation process of the expansive agent amount calculation formula of the present application is as follows:

[0069] (1) Stress and strain in the steel cylinder and the concrete

[0070] Let the steel cylinder be subjected to the expansion pressure p due to the expansion of the concrete, and the circumferential stress σ θ and the circumferential stress σ θ1 and the radial stress σ r1 in the concrete generated thereby be represented as

[0071] σ θ1 = σ r1 = p

[0072] The corresponding circumferential strain ε θ and the circumferential strain ε θ1 and the radial strain ε r1 in the concrete are represented as

[0073]

[0074] Under the joint action of stress σ r1 and volume expansion rate θ, considering the isotropic expansion (uniform expansion) of concrete, its radial strain is expressed as

[0075]

[0076] (2) Displacement coordination deformation of steel cylinder and concrete

[0077] The radial displacement u r of the steel cylinder and the radial displacement u r1 of the concrete are respectively expressed as

[0078]

[0079] From the displacement coordination deformation condition u r of the steel cylinder and the concrete, r1 is obtained

[0080]

[0081] Considering the counteracting effect of the volume shrinkage rate θ0 of the recycled concrete on the uniform expansion of the expansive agent, the volume expansion rate of the recycled concrete after mixing with the expansive agent is modified as

[0082]

[0083] In the formula, is the design constraint stress value of the concrete, where σ s is the yield stress of the steel cylinder, K is a safety factor of 3-5, that is, the steel cylinder needs to have sufficient safety reserves under the action of the expansive force; α is the cross-sectional shape coefficient of the steel cylinder. For a circular cross-section, α is 1; considering the different constraint stiffness of the rectangular cross-section steel cylinder to the concrete at the corners and the middle of the side length, some changes in the cross-sectional shape can be caused, so the expansive stress is appropriately reduced, and α is 0.5-0.7. After the volume expansion rate θ is calculated, the corresponding dosage of the expansive agent can be determined.

[0084] In some embodiments of the present application, when preparing the recycled concrete, 10-15% of the mass of cement is mixed with MgO mineral powder, and 30-50% of the mass of the MgO mineral powder is mixed with dry ice particles having a particle size of less than 1 cm in the preparation of the recycled concrete;

[0085] During the preparation process, the MgO mineral powder and the dry ice particles are fully stirred and uniformly mixed, and are then statically placed in a closed state for 45-60 minutes to allow CO2 after the gasification of the dry ice to react with the MgO to produce a carbonization reaction; then the excess CO2 gas is discharged by stirring for 5-10 minutes with a vibration rod, and finally the recycled concrete is fully stirred and then poured into a member.

[0086] It can be understood that after the above-mentioned carbonization treatment of mixing MgO-dry ice, the water stability of the recycled concrete can be improved, the erosion of chloride ions and other substances and the corrosion of steel bars can be prevented, and the durability can be improved.

[0087] Because the recycled concrete has high porosity, when used in humid or water environments (such as underground structures, pile foundations, shallow foundations, hydraulic structures, etc.), it is easy for chloride ions and other substances in the outside world (especially in water or soil) to invade, react with calcium in the concrete, generate calcium chloride and other powdery compounds with no strength, destroy the matrix strength, and cause steel corrosion. After mixing MgO mineral powder and dry ice and carbonization treatment, MgO will react with CO2 to generate MgO-CO2 compounds and adhere to the pore wall and the surface of the steel bar, forming a dense insoluble film that prevents the erosion of chloride ions and other substances to the concrete matrix and steel, strengthens the performance stability of the recycled concrete member used in humid and water environments and other harsh conditions, and improves its durability.

[0088] Further, with reference to Figures 1 to 6 , the experimental cases of the present application are as follows:

[0089] I. Determination method of expansion agent dosage

[0090] 1. Relationship between concrete expansion rate and expansion agent dosage (case)

[0091] Table 1 Relationship between concrete expansion rate and expansion agent dosage

[0092]

[0093] Note: 1. The strength grade of the prepared concrete is C40, the cement type is PO42.5R, and the expansion agent type is ordinary HEA type;

[0094] 2. The prepared concrete is mixed with 60 kg·m-3 of fly ash, and the curing period is 60 days;

[0095] 3. The expansion agent dosage is calculated according to “expansion agent dosage = expansion agent weight / (concrete weight + expansion agent weight) × 100%”; 2. Expansion agent dosage calculation (case)

[0096] Table 2 Calculation table of structure parameters of recycled concrete and expansion agent dosage

[0097]

[0098] Note: 1. The strength grade of the structure's concrete is C40;

[0099] 2. The expansion agent dosage in the concrete is determined by interpolating the data in Table 1 according to the calculated volume expansion rate θ in the table.

[0100] II. Implementation cases 1 and 2

[0101] Table 3 technical content and parameters of implementation case 1

[0102]

[0103]

[0104] Table 4 technical content and parameters of implementation case 2

[0105]

[0106]

[0107] It can be seen that the application can significantly improve the comprehensive performance of recycled concrete by adopting performance improvement measures such as incorporating spiral pipe-shaped steel fibers 400, intelligent hydrophobicity of electro-osmosis, stress constraint, MgO-dry ice water stability treatment, etc. in the preparation of recycled concrete, and can be used as building materials for important and key load-bearing components in structures.

[0108] The technical features of the above-described embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present disclosure.

[0109] The embodiments of the application are described in detail above in combination with the drawings, but the application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art in the technical field without departing from the purpose of the application.

Claims

1. A confined recycled concrete structure, characterized in that, include: A constraint cylinder having a constraint cavity enclosed by its inner wall; A constraint structure is provided on the inner wall; The concrete structure body is cast and molded in the constrained cavity, wherein the concrete structure body is also provided with an electroosmotic drainage device for draining water, and the concrete structure body is distributed with spiral tubular steel fibers. The recycled concrete is provided with an appropriate amount of expansive agent, wherein the expansive agent content is calculated according to the volume expansion rate as follows Control is performed: wherein, is the volume expansion ratio of the recycled concrete after incorporating the expansive agent, is the volume shrinkage ratio of the recycled concrete without incorporating the expansive agent; is the elastic modulus of the recycled concrete, is the Poisson's ratio of the recycled concrete; , , is the elastic modulus of the constraint cylinder, the diameter or the long side of the rectangle of the constraint cylinder, and the thickness of the cylinder wall, respectively; is the design constraint stress value of the concrete, is calculated in the following manner: wherein, K is 4-6 for the stress reserve coefficient, i.e. the volume expansion rate generated after the incorporation of the expansive agent in the concrete When K = 1, the maximum expansion circumferential stress in the restraint cylinder is its yield stress; When K > 1, the maximum expansion circumferential stress in the restraint cylinder is 1 / K (i.e. K) of its yield stress; A is the restraint cylinder cross-sectional shape coefficient, the circular cross-section A = 1, the rectangular cross-section A = 0.5-0.

7.

2. The confined recycled concrete structure of claim 1, wherein: The spiral tubular steel fiber is prepared by processing steel fibers with a diameter of 1 to 1.5 mm into a spring shape.

3. The confined recycled concrete structure of claim 2, wherein: The length L of the spiral tubular steel fiber is 3-5 cm, the spiral diameter d is 3-6 mm, and the spiral pitch h is 3-5 mm.

4. The confined recycled concrete structure of claim 1, wherein: The electroosmotic drainage device includes a controller, an electroosmotic anode, an electroosmotic cathode, and a humidity sensor. The electroosmotic anode and the electroosmotic cathode are arranged opposite to each other. The humidity sensor is used to monitor the moisture content within the concrete structure. The controller is adapted to receive information from the humidity sensor and control the electroosmotic anode and the electroosmotic cathode to generate an electric field between them suitable for driving the movement of water molecules. A permeable geotextile is provided around the electroosmotic cathode, which is suitable for draining water.

5. The confined recycled concrete structure of claim 1, wherein: Multiple constraint structures are provided, and the constraint structures are spaced apart along the inner wall to form multiple layers. The constraint structures in each layer are spaced vertically from each other, and the constraint structures in adjacent layers are staggered in the circumferential direction.

6. The confined recycled concrete structure of claim 5, wherein: The constraint structure includes at least one of a constraint ring, a constraint block, or a constraint pin.

7. The confined recycled concrete structure of claim 6, wherein: When the constraint structure includes at least one of constraint block or constraint pin, the constraint structure in each layer has the same structure, or at least two constraint structure in at least one layer have different structures. And / or the constraint cylinder is a cylindrical steel cylinder or a rectangular steel cylinder.

8. A method of producing a confined recycled concrete structure according to any one of claims 1 to 7, characterized in that, Includes the following steps: Recycled concrete is prepared using recycled aggregates, cement, and sand. Add 0.5-1.5% of the spiral tubular steel fiber by weight of the recycled concrete to the recycled concrete and mix thoroughly. The constraint structure is installed on the inner wall of the constraint cylinder, and the electroosmotic hydrophobic device is embedded therein. Recycled concrete is poured into the confined cylinder to form a confined recycled concrete structure.

9. A method of producing a confined recycled concrete structure according to claim 8, characterized in that: Incorporating an appropriate amount of expansive agent in the recycled concrete, wherein the expansive agent is incorporated in an amount calculated based on the volume expansion rate Control: wherein, is the volume expansion ratio of the recycled concrete after incorporating the expansive agent, is the volume shrinkage ratio of the recycled concrete without incorporating the expansive agent; is the elastic modulus of the recycled concrete, is the Poisson's ratio of the recycled concrete; , , are the elastic modulus of the restraint cylinder, the diameter or the long side of the rectangle of the restraint cylinder, and the thickness of the cylinder wall, respectively; is the design restraint stress value of the concrete, is calculated in the following manner: wherein, K is 4-6 for the stress reserve coefficient, i.e. the volume expansion rate generated after mixing the expansive agent in the concrete When K = 1, the maximum expansion circumferential stress in the restraint cylinder is its yield stress; When K > 1, the maximum expansion circumferential stress in the restraint cylinder is 1 / K (i.e. K is the restraint cylinder cross-section shape coefficient, the circular cross-section K = 1, the rectangular cross-section K = 0.5-0.

7.

10. The method of claim 8, wherein the method further comprises: When preparing recycled concrete, 10-15% of MgO mineral powder by weight of cement and 30-50% of dry ice particles by weight of MgO mineral powder are added to the recycled concrete. The particle size of the dry ice particles is less than 1 cm. In the preparation process, MgO mineral powder and dry ice particles are first thoroughly mixed and then left to stand in a closed state for 45 to 60 minutes to allow the CO2 produced by the vaporization of dry ice to undergo a carbonization reaction with MgO. Then, the mixture is stirred with a vibrator for 5 to 10 minutes to remove excess CO2 gas. Finally, it is thoroughly mixed with recycled concrete before the component is poured.

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