Precast concrete column with built-in recycled component, and construction method therefor

Abstract

Disclosed in the present invention are a precast concrete column with a built-in recycled component, and a construction method therefor. The precast concrete column comprises a recycled component, longitudinal column bars, spiral stirrups, common or composite stirrups, first connectors, second connectors, new concrete and grouting sleeves, wherein the recycled component comprises old stirrups, old longitudinal bars and old concrete. In the present invention, old beam-type components and old column-type components are directly utilized, instead of breaking old concrete therein into recycled blocks or recycled aggregate for reuse, thereby greatly simplifying a treatment process, significantly increasing the cyclic utilization rate of the old concrete, significantly reducing the amount of new concrete and corresponding cement, and achieving a significant energy-saving and carbon-reduction effect. Moreover, in the present invention, rebar connectors are further provided, such that the old stirrups serve an additional transverse confining effect on the longitudinal column bars, and the old longitudinal bars and the longitudinal column bars jointly bear loads; thus, the amount of spiral stirrups and longitudinal column bars used in the precast concrete column can be properly reduced, and significant economic benefits are achieved.

Description

Precast concrete column with built-in recycled components and construction method thereof Technical Field

[0001] The present invention relates to the technical field of recycling waste concrete, and in particular to a precast concrete column with a built-in recycled component and a construction method thereof. Background Art

[0002] With the rapid development of urban construction and the orderly advancement of urban renewal in my country, the green and efficient reuse of demolished old concrete components has become a growing focus of public attention. Currently, a common practice is to crush the old concrete from old concrete components into small-scale recycled aggregate or blocks. This is then mixed with cement and other binders to create recycled aggregate concrete, or mixed with new concrete to form recycled block concrete. However, the crushing process is not only cumbersome but also generates significant energy consumption and unusable powder, significantly reducing the recycling rate of old concrete. Furthermore, preparing recycled aggregate concrete consumes significant amounts of cement, with new concrete comprising approximately 70% of recycled block concrete. The production of this new concrete also consumes significant amounts of cement. Because cement production generates significant amounts of CO2, the carbon reduction effect of this current practice needs to be further improved. Furthermore, the old steel bars recovered from the old concrete components during the crushing process must undergo complex processes such as smelting before they can be reused. These complex processes also consume significant energy and emit significant amounts of CO2, resulting in limited carbon reduction. In summary, strategies for recycling and reusing old concrete components require further improvement. Therefore, if old concrete components can be directly used in the production of new components without crushing, this problem will undoubtedly be greatly alleviated. However, there is currently no precedent for how to simply and efficiently use old concrete components in the production of new components.

[0003] Precast concrete components are widely used in construction due to their rapid construction speed, high degree of industrialization, and minimal environmental pollution. Columns are important vertical load-bearing components in building structures. During the precast concrete column production process, if recycled components, obtained through simple processing, could be directly cast inside new precast concrete columns, this would undoubtedly be an effective way to directly reuse old concrete components. Summary of the Invention

[0004] Currently, existing technologies are unable to achieve the recycling and reuse of old beam-type components and old column-type components at the component level. The present invention provides precast concrete columns with built-in recycled components and a construction method thereof. It is the first to propose an effective countermeasure for recycling and reusing old beam-type components and old column-type components as a whole in precast concrete columns, which has a significant carbon emission reduction effect.

[0005] To achieve the purpose of the present invention, the present invention provides a precast concrete column with a built-in recycled component, comprising a recycled component, column longitudinal reinforcement, spiral stirrups, ordinary or composite stirrups, a first connector, a second connector, new concrete, and a grouting sleeve;

[0006] The recycled component is enclosed in new concrete, the recycled component includes old stirrups, old longitudinal reinforcement and old concrete, the height and cross-sectional width of the recycled component are respectively smaller than the height and cross-sectional width of the precast concrete column, and the volume of the recycled component is not less than 40% of the volume of the precast concrete column;

[0007] The column longitudinal reinforcement is located in the new concrete;

[0008] The grouting sleeve is located below the regeneration component;

[0009] The setting range of the ordinary or composite stirrups is the area where the grouting sleeve is located;

[0010] The setting range of the spiral stirrups is the area where the grouting sleeve is not located;

[0011] The first connector is made of steel bars and is used to connect the old stirrups and the column longitudinal bars. The first connector is set in the area where the regenerated components are located.

[0012] The second connector is made of steel bars and is used to connect the old longitudinal bars and the column longitudinal bars; the second connector is set within the upper longitudinal range of 0-500 mm and the lower longitudinal range of 0-500 mm in the area where the recycled component is located;

[0013] Except for the inside of the grouting sleeve, new concrete is poured around the grouting sleeve and on the top, bottom and sides of the recycled component. The new concrete is natural aggregate concrete with a maximum particle size of coarse aggregate not greater than 20 mm, or recycled aggregate concrete, or recycled aggregate concrete containing recycled sand from engineering waste.

[0014] Furthermore, the net distance between the lower surface of the regeneration component and the grouting sleeve is 50-100 mm.

[0015] Furthermore, the cross-sectional width of the recycled component is at least 150 mm smaller than the cross-sectional width of the precast concrete column.

[0016] Furthermore, the recycled component is obtained by removing the stirrup protective layer from the old concrete component obtained from the demolition of the old building (structure) and performing surface roughening treatment.

[0017] Furthermore, the compressive strength of the new concrete is not lower than the compressive strength of the old concrete in the recycled component.

[0018] Furthermore, the first connecting piece buckles the column longitudinal reinforcement from the outside, and the first connecting piece is welded to the old stirrups.

[0019] Furthermore, the yield strength of the steel bars of the first connecting member is not lower than the yield strength of the old stirrups.

[0020] Furthermore, the second connecting piece is welded to the old longitudinal reinforcement and the column longitudinal reinforcement respectively.

[0021] Furthermore, the yield strength of the steel bars of the second connecting member is not lower than the smaller value of the yield strength of the old longitudinal bars and the yield strength of the column longitudinal bars.

[0022] The construction method of the precast concrete column with built-in recycled components comprises the following steps:

[0023] (1) Processing and manufacturing column longitudinal reinforcement, spiral stirrups, ordinary or composite stirrups, first connectors and second connectors;

[0024] (2) Remove the protective layer of the stirrups of the old concrete component and perform surface roughening to obtain a recycled component, and perform local treatment on the part of the recycled component where the second connector will be set, so that the welding surface of the old longitudinal reinforcement in this part is exposed;

[0025] (3) Arrange the column longitudinal reinforcement and grouting sleeves, tie the spiral stirrups to the column longitudinal reinforcement, and tie the ordinary or composite stirrups to the grouting sleeves to form a reinforcement cage;

[0026] (4) Adjust the steel cage prepared in step (3) to an upright state, and hoist the regenerated component into the steel cage from top to bottom;

[0027] (5) Buckle the column longitudinal reinforcement with the first connector from the outside, weld the first connector to the adjacent old stirrups, and weld the second connector to the adjacent column longitudinal reinforcement and the old longitudinal reinforcement;

[0028] (6) Complete the formwork and horizontal formwork of the precast concrete columns with built-in recycled components, hoist the steel cage and recycled components constructed in steps (4) and (5) into the cavity surrounded by the formwork in a horizontal manner, and complete the detailed positioning;

[0029] (7) Pour sufficient new concrete into the cavity enclosed by the formwork, vibrate it thoroughly and maintain it.

[0030] Compared with the prior art, the present invention has the following advantages and effects:

[0031] (1) The present invention directly utilizes old beam-type components or old column-type components instead of crushing them into recycled blocks or recycled aggregates for reuse, which greatly simplifies the processing process, significantly improves the recycling rate of old concrete, and significantly reduces the amount of new concrete and the corresponding fresh cement, with an outstanding carbon emission reduction effect.

[0032] (2) The present invention sets a first connecting piece to connect the old stirrups in the recycled component with the column longitudinal reinforcement in the precast concrete column, which can make the old stirrups play an additional lateral restraining effect on the column longitudinal reinforcement, cleverly play the unique restraining role of the old stirrups in the precast concrete column, and thus appropriately reduce the amount of spiral stirrups in the precast concrete column, which has obvious economic benefits.

[0033] (3) The present invention sets a second connecting piece to connect the old longitudinal reinforcement in the recycled component with the column longitudinal reinforcement in the precast concrete column, so that the old longitudinal reinforcement and the column longitudinal reinforcement can be subjected to force synergistically. The longitudinal tensile effect of the old longitudinal reinforcement under earthquake action or large eccentricity can be exerted to a certain extent, thereby appropriately reducing the amount of column longitudinal reinforcement in the precast concrete column, which has obvious economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic diagram of the overall structure of a precast concrete column with a built-in regeneration component provided by an embodiment of the present invention;

[0035] FIG2 is a schematic diagram of a partial structure of a regeneration component in a precast concrete column with a built-in regeneration component according to an embodiment of the present invention;

[0036] 3 is a schematic diagram showing the positional relationship between the recycled component, column longitudinal reinforcement, and spiral stirrups in a precast concrete column with a built-in recycled component according to an embodiment of the present invention;

[0037] FIG4 is a schematic diagram showing the specific structures of the first connecting member and the second connecting member in the precast concrete column with built-in regeneration components according to an embodiment of the present invention;

[0038] 5 is a schematic diagram of the partial connection positions of the first connecting member and the second connecting member in the precast concrete column with built-in regeneration components according to an embodiment of the present invention;

[0039] In the figure: 1-recycled component; 2-column longitudinal reinforcement; 3-spiral stirrups; 4-ordinary or composite stirrups; 5-first connecting piece; 6-second connecting piece; 7-new concrete; 8-grouting sleeve; 9-old stirrups; 10-old longitudinal reinforcement; 11-old concrete. Modes for Carrying Out the Invention

[0040] The present invention will be further described in detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto. It should be pointed out that if there are any processes that are not particularly described in detail below, those skilled in the art can implement them with reference to the existing technology.

[0041] As shown in Figures 1, 2, 3, 4 and 5, the present invention provides a precast concrete column with a built-in recycled component, including a recycled component 1, column longitudinal reinforcement 2, spiral stirrups 3, ordinary or composite stirrups 4, a first connecting member 5, a second connecting member 6, new concrete 7 and a grouting sleeve 8.

[0042] The recycled component 1 includes old stirrups 9, old longitudinal reinforcements 10 and old concrete 11. The old longitudinal reinforcements 10 are located inside the old concrete 11, and the old stirrups 9 are located outside the old longitudinal reinforcements 10, and the outermost side of the old stirrups 9 is basically flush with the outer surface of the old concrete 11; the height and cross-sectional width of the recycled component 1 are respectively smaller than the height and cross-sectional width of the precast concrete column; the volume of the recycled component 1 is not less than 40% of the volume of the precast concrete column.

[0043] A grouting sleeve 8 is installed below the regeneration component 1, with a gap between them. The net distance between the lower surface of the regeneration component 1 and the grouting sleeve 8 is 50-100 mm. Conventional or composite stirrups 4 are installed in the area where the grouting sleeve 8 is located; spiral stirrups 3 are installed in the area outside the grouting sleeve 8.

[0044] The grouting sleeve 8 is a connecting piece used to connect the prefabricated column with the frame node or column at its lower end. The longitudinal reinforcement of the frame node or column at its lower end will be inserted into the grouting sleeve during construction, and then grouting material will be poured into the sleeve to achieve the purpose of connection.

[0045] The regenerated component 1 is surrounded by new concrete 7, and the column longitudinal reinforcement 2 is longitudinally arranged in the new concrete 7. The first connecting piece 5 is made of steel bars and is used to connect the old stirrups 9 and the column longitudinal reinforcement 2; the setting range of the first connecting piece 5 is the area where the regenerated component 1 is located; specifically, the first connecting piece 5 buckles the column longitudinal reinforcement 2 from the outside, and the first connecting piece 5 is welded to the old stirrups 9. The second connecting piece 6 is made of steel bars and is used to connect the old longitudinal reinforcement 10 and the column longitudinal reinforcement 2; the setting range of the second connecting piece 6 is the upper longitudinal range of 0-500 mm and the lower longitudinal range of 0-500 mm in the area where the regenerated component 1 is located. When considering earthquake effects or large bias conditions, the bending moment of the regenerated component 1 is the largest within the upper and lower ends. Therefore, arranging the second connecting piece 6 within a certain range at both ends can allow the old longitudinal reinforcement 10 and the column longitudinal reinforcement 2 to cooperate in force, thereby exerting the longitudinal tensile effect of the old longitudinal reinforcement 10; specifically, the second connecting piece 6 is welded to the old longitudinal reinforcement 10 and the column longitudinal reinforcement 2 respectively. As an embodiment, the shape of the first connecting piece 5 is , the shape of the second connecting member 6 is .

[0046] The new concrete 7 is natural aggregate concrete or recycled aggregate concrete or recycled aggregate concrete containing recycled sand from construction waste with a maximum coarse aggregate size of no more than 20 mm; except for the inside of the grouting sleeve 8, new concrete 7 is poured on the top, bottom and around the recycled component 1, and new concrete is also poured around the grouting sleeve 8.

[0047] In some embodiments of the present invention, the recycled component 1 is obtained by removing the stirrup protective layer from an old concrete component obtained by demolishing an old building (structure) and performing a surface roughening treatment.

[0048] In some embodiments of the present invention, the precast concrete column has a height of 3000 mm, a cross-sectional width of 600 mm, and a stirrup cover thickness of 25 mm.

[0049] In some embodiments of the present invention, the compressive strength of the new concrete 7 is 60 MPa, and the compressive strength of the old concrete 11 of the recycled structure 1 is 50 MPa.

[0050] In some embodiments of the present invention, the column longitudinal reinforcement 2 adopts HRB400 hot-rolled steel bars with a diameter of 20 mm; the spiral stirrups 3 adopt HRB400 hot-rolled steel bars with a diameter of 10 mm; the ordinary or composite stirrups 4 adopt HRB400 hot-rolled steel bars with a diameter of 10 mm; the old stirrups 9 adopt HRB400 hot-rolled steel bars with a diameter of 10 mm; and the old longitudinal reinforcement 10 adopts HRB400 hot-rolled steel bars with a diameter of 20 mm.

[0051] In some embodiments of the present invention, the first connecting member 5 and the second connecting member 6 are both made of HRB400 hot-rolled steel bars with a diameter of 6 mm.

[0052] The above-mentioned construction method of a precast concrete column with built-in recycled components includes the following steps:

[0053] (1) Processing and manufacturing column longitudinal reinforcement 2, spiral stirrups 3, ordinary or composite stirrups 4, first connectors 5 and second connectors 6;

[0054] (2) removing the protective layer of the stirrups of the old concrete component and performing surface roughening treatment to obtain a recycled component 1, and performing local treatment on the portion of the recycled component 1 where the second connector 6 is to be provided, so that the welding surface of the old longitudinal reinforcement 10 in this portion is exposed;

[0055] (3) Arrange the column longitudinal reinforcement 2 and the grouting sleeve 8, tie the spiral stirrups 3 to the column longitudinal reinforcement 2, and tie the ordinary or composite stirrups 4 to the grouting sleeve 8 to form a steel cage;

[0056] (4) Adjust the steel cage prepared in step (3) to an upright state, and hoist the regeneration component 1 from top to bottom into the steel cage;

[0057] (5) Buckle the column longitudinal reinforcement 2 with the first connector 5 from the outside, weld the first connector 5 to the adjacent old stirrup 9, and weld the second connector 6 to the adjacent column longitudinal reinforcement 2 and the old longitudinal reinforcement 10;

[0058] (6) Complete the formwork and horizontal formwork of the precast concrete column with built-in recycled components, hoist the steel cage and recycled component 1 constructed in steps (4) and (5) into the cavity surrounded by the formwork in a horizontal manner, and complete the detailed positioning;

[0059] (7) Pour sufficient new concrete 7 into the cavity enclosed by the formwork, vibrate it thoroughly and then cure it.

[0060] Traditionally, old concrete components have been crushed to remove the internal steel bars. The crushed large concrete blocks are then directly used as recycled blocks, or the large blocks are crushed multiple times to refine them into recycled aggregate for reuse. Whether using recycled blocks to prepare recycled block concrete or recycled aggregate concrete to prepare recycled aggregate concrete, large amounts of fresh cement and other cementitious materials are required. Cement production is not only energy-intensive but also emits significant carbon emissions. The multiple crushing processes inevitably produce a large amount of difficult-to-use powder, significantly reducing the recycling rate of the old concrete. Furthermore, the old steel bars removed during the crushing of old concrete components also need to undergo complex processes such as smelting before they can be reused as resources. These complex processes also consume a lot of energy and emit a large amount of CO2, resulting in a limited carbon reduction effect.

[0061] In order to solve the above problems, the present invention proposes for the first time the idea of ​​directly recycling old beam-type components and old column-type components at the component level, instead of crushing the concrete therein into recycled blocks or recycled aggregates. This not only greatly simplifies the processing process, but also avoids the output of a large amount of powder. More importantly, it can significantly reduce the amount of new concrete and the corresponding fresh cement, and the energy-saving and carbon-reduction effects are significant. At the same time, since the steel bars inside the old concrete components can also provide important assistance in the service process of the new components, it not only avoids the tedious removal process of the old steel bars and the subsequent smelting and other complex processes, as well as the corresponding energy consumption and CO2 emissions, but also reduces the reinforcement requirements of the new components to a certain extent, which undoubtedly makes the present invention have greater advantages. Prior to this, there have been no reports internationally on the direct recycling of old beam-type components and old column components in new components.

[0062] According to the present invention, although the steel bars inside the old concrete components are no longer taken out and sold, which seems to reduce a certain amount of economic income, and this is also the main reason why predecessors found it difficult to think of directly recycling old beam components and old column components, the equipment and labor costs related to the crushing of old concrete components and the removal of steel bars can be saved, the expenses for transporting and dumping a large amount of powder can be avoided, the reinforcement requirements of new components are reduced because the steel bars inside the old concrete components play a certain load-bearing role, and the new concrete brought about by the direct recycling of old concrete components in new components and the corresponding fresh cement consumption are significantly reduced, resulting in cost savings. All these make the present invention have good comprehensive economic benefits.

[0063] In summary, the present invention has good benefits in social, economic and ecological aspects.

[0064] According to the method of the present invention, a series of embodiments can be developed, which does not limit the present invention in any form. Therefore, any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. Precast concrete columns with built-in recycled components, characterized in that: It comprises a recycled component (1), column longitudinal reinforcement (2), spiral stirrups (3), ordinary or composite stirrups (4), a first connecting piece (5), a second connecting piece (6), new concrete (7) and a grouting sleeve (8); The recycled component (1) is enclosed in new concrete (7), and the recycled component (1) includes old stirrups (9), old longitudinal bars (10) and old concrete (11). The height and cross-sectional width of the recycled component (1) are respectively smaller than the height and cross-sectional width of the precast concrete column, and the volume of the recycled component (1) is not less than 40% of the volume of the precast concrete column; The column longitudinal reinforcement (2) is located in the new concrete (7); The grouting sleeve (8) is located below the regeneration component (1); The setting range of the common or composite stirrups (4) is the area where the grouting sleeve (8) is located; The setting range of the spiral stirrup (3) is the area where the non-grouting sleeve (8) is located; The first connecting member (5) is made of steel bars and is used to connect the old stirrups (9) and the column longitudinal bars (2). The setting range of the first connecting member (5) is the area where the regenerated component (1) is located; The second connecting member (6) is made of steel bars and is used to connect the old longitudinal reinforcement (10) and the column longitudinal reinforcement (2); the second connecting member (6) is provided within the upper longitudinal range of 0-500 mm and the lower longitudinal range of 0-500 mm within the area where the regenerated component (1) is located; Except for the interior of the grouting sleeve (8), new concrete (7) is poured around the grouting sleeve (8) and the upper, lower and surrounding areas of the recycled component (1). The new concrete (7) is natural aggregate concrete with a maximum particle size of coarse aggregate not greater than 20 mm or recycled aggregate concrete or recycled aggregate concrete containing engineering slag recycled sand.

2. The precast concrete column with built-in recycled components according to claim 1, characterized in that: The net distance between the lower surface of the regeneration component (1) and the grouting sleeve (8) is 50-100 mm.

3. The precast concrete column with built-in recycled components according to claim 1, characterized in that: The cross-sectional width of the recycled component (1) is at least 150 mm smaller than the cross-sectional width of the precast concrete column.

4. The precast concrete column with built-in recycled components according to claim 1, characterized in that: The recycled component (1) is obtained by removing the stirrup protective layer from the old concrete component obtained from the demolition of the old building (structure) and performing surface roughening treatment.

5. The precast concrete column with built-in recycled components according to claim 1, characterized in that: The compressive strength of the new concrete (7) is not lower than the compressive strength of the old concrete (11) in the recycled component (1).

6. The precast concrete column with built-in recycled components according to claim 1, characterized in that: The first connecting piece (5) buckles the column longitudinal reinforcement (2) from the outside, and the first connecting piece (5) is welded to the old stirrup (9).

7. The precast concrete column with built-in recycled components according to claim 1, characterized in that: The yield strength of the steel bars of the first connecting member (5) is not lower than the yield strength of the old stirrups (9).

8. The precast concrete column with built-in recycled components according to claim 1, characterized in that: The second connecting piece (6) is welded to the old longitudinal reinforcement (10) and the column longitudinal reinforcement (2) respectively.

9. The precast concrete column with built-in recycled components according to any one of claims 1 to 8, characterized in that: The steel bar yield strength of the second connecting member (6) is not lower than the smaller value of the yield strength of the old longitudinal bar (10) and the yield strength of the column longitudinal bar (2).

10. A construction method for a precast concrete column with a built-in recycled component according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Processing and manufacturing column longitudinal reinforcement (2), spiral stirrups (3), ordinary or composite stirrups (4), first connecting members (5) and second connecting members (6); (2) removing the protective layer of the stirrups of the old concrete component and performing surface roughening treatment to obtain a regenerated component (1), and locally treating the portion of the regenerated component (1) where the second connecting member (6) is to be provided, so that the welding surface of the old longitudinal reinforcement (10) at the portion is exposed; (3) arranging the column longitudinal reinforcement (2) and the grouting sleeve (8), tying the spiral stirrups (3) to the column longitudinal reinforcement (2), and tying the ordinary or composite stirrups (4) to the grouting sleeve (8) to form a reinforcement cage; (4) Adjust the steel cage prepared in step (3) to an upright state, and hoist the regenerated component (1) into the steel cage from top to bottom; (5) The first connecting piece (5) is buckled onto the column longitudinal reinforcement (2) from the outside, the first connecting piece (5) is welded to the adjacent old stirrup (9), and the second connecting piece (6) is welded to the adjacent column longitudinal reinforcement (2) and the old longitudinal reinforcement (10); (6) Complete the formwork and horizontal formwork of the precast concrete column with built-in recycled components, hoist the steel cage and recycled components (1) constructed in steps (4) and (5) into the cavity surrounded by the formwork in a horizontal manner, and complete the detailed positioning; (7) Pour new concrete (7) into the cavity enclosed by the formwork, vibrate it thoroughly and then cure it.

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