Prefabricated floor slab and profiled steel plate composite floor slab which directly apply old slabs, and construction method

Abstract

Disclosed in the present invention are a prefabricated floor slab and profiled steel plate composite floor slab which directly apply old slabs, and a construction method. The prefabricated floor slab comprises an old concrete slab, new concrete, a slab bottom reinforcing mesh, a slab surface reinforcing mesh, rebar dowels and protruding tooth bars. The profiled steel plate composite floor slab comprises an old concrete slab, new concrete, a slab surface reinforcing mesh, rebar dowels, a profiled steel plate, slab bottom longitudinal load-bearing steel bars and slab bottom transverse distribution bars. This present invention directly uses old concrete slabs instead of crushing them into recycled blocks or recycled aggregates for reuse, thus significantly simplifying the processing procedures, greatly increasing the recycling rate of old concrete, substantially reducing the dosage of new concrete and the corresponding amount of cement, and achieving a prominent carbon emission reduction effect. Vertically drilling through holes in old concrete slabs, inserting rebar dowels into said through holes, and filling gaps therebetween with a high-strength grouting material are used for further enhancing the shear resistance at the interfaces between the new concrete and old concrete.

Description

Prefabricated floor slabs directly utilizing old slabs and combined floor slabs with corrugated steel plates and construction method Technical Field

[0001] The present invention relates to the technical field of recycling waste concrete, and in particular to a prefabricated floor slab and a corrugated steel plate combined floor slab directly utilizing waste concrete slabs, and a construction method thereof. Background Art

[0002] With the rapid development of urban construction, the recycling and reuse of old concrete components has attracted increasing public attention. The current practice involves crushing old concrete components into small-scale recycled aggregate or blocks, then adding cement and other binders to create recycled aggregate concrete, or mixing with new concrete to form recycled block concrete. However, crushing old concrete components into recycled aggregate or blocks is a complex process, and the crushing process also produces a large amount of difficult-to-use powder, significantly reducing the recycling rate of the old concrete. Furthermore, preparing recycled aggregate concrete consumes a large amount of cement, and recycled block concrete, which comprises up to 70% new concrete, also consumes a large amount of cement in its production. Because cement production generates significant CO2 emissions, the carbon reduction effect of this current practice needs to be further improved. Therefore, strategies for recycling and reusing old concrete components require further improvement. Directly utilizing old concrete components in the production of new components without crushing them would undoubtedly significantly alleviate these issues. However, there is currently no established method for simply and efficiently utilizing old concrete components in the production of new components.

[0003] Precast concrete components are widely used in construction projects due to their rapid construction speed, high degree of industrialization, and minimal environmental pollution. Floor slabs are important horizontal components in building structures. During the production of precast and corrugated steel composite floor slabs, pouring the old concrete slab directly into the new one is an effective way to reuse the old concrete slab. Summary of the Invention

[0004] Currently, existing technologies are unable to achieve the component-level recycling and reuse of old concrete slabs. The present invention provides prefabricated floor slabs and corrugated steel plate composite floor slabs that directly utilize old concrete slabs and their construction methods. It is the first to propose an effective countermeasure for recycling and reusing old concrete slabs as a whole in prefabricated floor slabs and corrugated steel plate composite floor slabs, which has a significant carbon emission reduction effect.

[0005] In order to achieve the purpose of the present invention, the present invention provides a prefabricated floor slab that directly utilizes old concrete slabs, comprising old concrete slabs, new concrete, a bottom steel mesh, a surface steel mesh, steel bar inserts, and an overhanging rack; the length and width of the old concrete slab are respectively smaller than the length and width of the prefabricated floor slab, and the volume of the old concrete slab is not less than 50% of the volume of the prefabricated floor slab; the new concrete is natural aggregate concrete or recycled aggregate concrete or recycled aggregate concrete containing recycled sand from engineering waste soil with a maximum particle size of coarse aggregate not greater than 20 mm; in the old concrete slab, ... Through holes are drilled vertically along the upper edge of the earth slab, and steel bar inserts are inserted into the through holes; the gaps between the through holes and the steel bar inserts are filled with high-strength grouting material; the bottom steel mesh and the surface steel mesh are located below and above the old concrete slab respectively; the upper longitudinal steel bars inside the old concrete slab are connected to the longitudinal steel bars of the surface steel mesh; the overhanging racks are located on the side walls of the precast floor slab, and steel components are inserted into the overhanging racks, and the steel components are extended in the opposite direction into the main body of the precast floor slab; new concrete is poured above, below and around the old concrete slab and inside the overhanging racks.

[0006] The present invention also provides a corrugated steel plate composite floor slab that directly utilizes old concrete slabs, comprising an old concrete slab, new concrete, a slab surface steel mesh, steel bar inserts, a corrugated steel plate, longitudinal stress-bearing steel bars at the bottom of the slab, and transverse distribution bars at the bottom of the slab; the length and width of the old concrete slab are respectively smaller than the length and width of the corrugated steel plate composite floor slab; the new concrete is natural aggregate concrete or recycled aggregate concrete with a maximum particle size of coarse aggregate not exceeding 20 mm, or recycled aggregate concrete, or recycled aggregate concrete containing recycled sand from engineering waste soil; through holes are vertically drilled on the old concrete slab, steel bar inserts are inserted into the through holes, and the gaps between the through holes and the steel bar inserts are filled with high-strength grouting material; the slab surface steel mesh is located above the old concrete slab; the internal upper longitudinal steel bars of the old concrete slab are connected to the longitudinal steel bars of the slab surface steel mesh; the corrugated steel plate is located below the old concrete slab, and the longitudinal stress-bearing steel bars at the bottom of the slab and transverse distribution bars at the bottom of the slab are arranged on the corrugated steel plate; new concrete is poured above, below, and around the old concrete slab.

[0007] Furthermore, for the prefabricated floor slabs that directly utilize old concrete slabs, the steel components extend inversely into the prefabricated floor slab body by no less than 50 mm, and the steel components are steel bars, angle steels, or I-shaped steels with a yield strength of no less than 235 MPa.

[0008] Furthermore, the length and width of the old concrete slab are at least 80 mm smaller than the length and width of the prefabricated floor slab or the corrugated steel plate composite floor slab.

[0009] Furthermore, the upper and lower surfaces of the old concrete slab are each cut to a thickness of 5-20 mm and roughened.

[0010] Furthermore, the old concrete slab is a concrete slab produced by demolishing old buildings or structures.

[0011] Furthermore, the compressive strength of the new concrete is not lower than the compressive strength of the old concrete slab.

[0012] Furthermore, the length of the steel bar insert is 10-30 mm greater than the original thickness of the old concrete slab and not greater than the thickness of the prefabricated floor slab or the corrugated steel plate composite floor slab.

[0013] The construction method of prefabricated floor slabs directly utilizing old concrete slabs comprises the following steps:

[0014] (1) Tie the bottom steel mesh and the surface steel mesh of the slab, and place the bottom steel mesh on top of the bottom formwork; lay a protective layer pad between the bottom steel mesh and the bottom formwork;

[0015] (2) Drill vertical through holes on the old concrete slab, insert the steel bars into the through holes and fill the gap between the two with high-strength grouting material;

[0016] (3) Insert the steel component inside the extended rack, and then extend the steel component into the main body of the prefabricated floor slab;

[0017] (4) Pour a layer of new concrete into the casting mold. The height of this new concrete layer exceeds the steel mesh at the bottom of the slab, and vibrate it to make it dense.

[0018] (5) Place the old concrete slab that has been fully moistened in advance directly on the new concrete layer poured in step (4), and apply a vertical downward vibration pressure on the upper surface of the old concrete slab for a duration of not less than 2 minutes;

[0019] (6) A slab surface reinforcement mesh is laid on top of the old concrete slab. The slab surface reinforcement mesh is spot-welded to the adjacent reinforcement bars. Pre-bent reinforcement bars are used to weld the upper longitudinal reinforcement of the old concrete slab to the longitudinal reinforcement of the slab surface reinforcement mesh. Then, sufficient new concrete is poured into the casting mold, vibrated sufficiently, and maintained.

[0020] The construction method of the corrugated steel plate composite floor slab directly utilizing the old concrete slab comprises the following steps:

[0021] (1) Arrange longitudinal stress-bearing reinforcement and transverse distribution reinforcement at the bottom of the corrugated steel plate;

[0022] (2) Drill through holes in the old concrete slab, insert the steel bars into the through holes and fill the gap between the two with high-strength grouting material;

[0023] (3) Pour a layer of new concrete into the casting mold. The height of this new concrete layer exceeds the transverse distribution reinforcement at the bottom of the slab, and vibrate it to make it dense.

[0024] (4) Place the old concrete slab that has been fully moistened in advance directly on the layer of new concrete poured in step (3), and apply a vertical downward vibration pressure on the upper surface of the old concrete slab for a duration of not less than 2 minutes;

[0025] (5) A slab surface reinforcement mesh is laid on top of the old concrete slab. The slab surface reinforcement mesh is spot welded to the adjacent reinforcement bars. The upper longitudinal reinforcement of the old concrete slab is welded to the longitudinal reinforcement of the slab surface reinforcement mesh using pre-bent reinforcement bars. Then, sufficient new concrete is poured into the casting mold, vibrated sufficiently, and maintained.

[0026] Compared with the prior art, the present invention has the following advantages and effects:

[0027] (1) Directly utilizing old concrete slabs instead of crushing them into recycled blocks or recycled aggregates for reuse 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 a significant carbon emission reduction effect.

[0028] (2) Overhanging racks are provided at the ends of the floor slabs, and steel components are arranged near the connection surface between the overhanging racks and the main body of the floor slabs. During on-site assembly, the overhanging racks are placed on the upper surface of the prefabricated composite beams to bear the load during construction, thereby solving the current problem of high costs and complex construction caused by the need to erect a large number of vertical supports on the construction site. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic diagram of the overall structure of a prefabricated floor slab directly utilizing old concrete slabs provided by an embodiment of the present invention;

[0030] FIG2 is a schematic diagram of the overall structure of a composite floor slab made of corrugated steel plates that directly utilizes old concrete slabs, provided by an embodiment of the present invention;

[0031] 3 is a schematic diagram of the partial structure of the old concrete slab in the prefabricated floor slab and the corrugated steel plate composite floor slab directly utilizing the old concrete slab in an embodiment of the present invention;

[0032] FIG4 is a schematic diagram of a partial structure of steel components in a prefabricated floor slab that directly utilizes old concrete slabs according to an embodiment of the present invention;

[0033] In the figure: 1- old concrete slab; 2- new concrete; 3- reinforcement mesh at the bottom of the slab; 4- reinforcement mesh at the surface of the slab; 5- reinforcement bar inserts; 6- overhanging rack; 7- corrugated steel plate; 8- hole; 9- steel component; 10- longitudinal stress-bearing reinforcement at the bottom of the slab; 11- transverse distribution reinforcement at the bottom of the slab. Modes for Carrying Out the Invention

[0034] 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.

[0035] As shown in Figures 1, 3, and 4, the present invention provides a prefabricated floor slab that directly utilizes old concrete slabs, including an old concrete slab 1, new concrete 2, a bottom steel mesh 3, a surface steel mesh 4, steel bar inserts 5, and an overhanging rack 6; the length and width of the old concrete slab 1 are at least 80 mm smaller than the length and width of the prefabricated floor slab, respectively, and the volume of the old concrete slab 1 is not less than 50% of the volume of the prefabricated floor slab; the upper and lower surfaces of the old concrete slab 1 are each reduced in thickness by 5-20 mm and roughened to increase the roughness of the interface between the new and old concrete; the new concrete 2 is natural aggregate concrete or recycled aggregate concrete with a maximum coarse aggregate size of not more than 20 mm, or recycled aggregate containing recycled sand from engineering waste. Concrete; vertical through holes 8 are drilled on the old concrete slab 1, and steel bar insertions 5 are inserted into the through holes 8; the gap between the through holes 8 and the steel bar insertions 5 is filled with high-strength grouting material, and the steel bar insertions 5 can further enhance the shear resistance of the interface between the new and old concrete; the bottom steel mesh 3 and the surface steel mesh 4 are respectively located below and above the old concrete slab 1; the internal upper longitudinal steel bars of the old concrete slab 1 are connected to the longitudinal steel bars of the surface steel mesh 4; the overhanging rack 6 is located on the side wall of the precast floor slab, and a steel component 9 is inserted into the overhanging rack 6, and the steel component 9 extends into the main body of the precast floor slab in the reverse direction by not less than 50 mm; new concrete 2 is poured on the upper, lower and surrounding areas of the old concrete slab 1 and inside the overhanging rack 6.

[0036] In some embodiments of the present invention, the prefabricated floor slabs directly utilizing old concrete slabs have a width of 600 mm, a length of 3000 mm, a slab thickness of 150 mm, and a protective layer thickness of 15 mm.

[0037] In some embodiments of the present invention, the compressive strength of the new concrete 2 is 30 MPa, and the compressive strength of the old concrete slab 1 is 25 MPa.

[0038] In some embodiments of the present invention, the bottom steel mesh 3 and the surface steel mesh 4 are formed by binding steel bars along the span direction and along the width direction, and the reinforcement along the span direction is C10@200; the reinforcement along the width direction is C8@200.

[0039] The above-mentioned construction method of prefabricated floor slabs directly utilizing old concrete slabs comprises the following steps:

[0040] (1) Tie the bottom steel mesh 3 and the surface steel mesh 4, and place the bottom steel mesh 3 above the bottom formwork; lay a protective layer pad between the bottom steel mesh 3 and the bottom formwork;

[0041] (2) Drill a through hole 8 vertically on the old concrete slab 1, insert the steel bar 5 into the through hole 8 and fill the gap between the two with high-strength grouting material;

[0042] (3) Insert the steel component 9 into the extended rack 6, and extend the steel component 9 into the main body of the prefabricated floor;

[0043] (4) Pour a layer of new concrete 2 into the casting mold. The height of this layer of new concrete 2 exceeds the steel mesh 3 at the bottom of the slab, and vibrate it to make it dense.

[0044] (5) Place the old concrete slab 1 that has been fully moistened in advance directly on the layer of new concrete 2 poured in step (4), and apply a vertical downward vibration pressure on the upper surface of the old concrete slab 1 for a duration of not less than 2 minutes;

[0045] (6) A slab surface reinforcement mesh 4 is laid on top of the old concrete slab 1. The slab surface reinforcement mesh 4 is locally spot-welded to the adjacent reinforcement bars 5. The upper longitudinal reinforcement of the old concrete slab 1 is welded to the longitudinal reinforcement of the slab surface reinforcement mesh 4 using pre-bent reinforcement bars. Then, sufficient new concrete 2 is poured into the casting mold, vibrated sufficiently, and cured.

[0046] As shown in FIG2 , a corrugated steel plate composite floor slab directly utilizing old concrete slabs comprises an old concrete slab 1, new concrete 2, a slab surface reinforcement mesh 4, reinforcement bar inserts 5, a corrugated steel plate 7, longitudinal stress-bearing reinforcement bars 10 at the bottom of the slab, and transverse distribution bars 11 at the bottom of the slab. The length and width of the old concrete slab 1 are at least 80 mm smaller than those of the corrugated steel plate composite floor slab, respectively. The upper and lower surfaces of the old concrete slab 1 are each reduced in thickness by 5-20 mm and roughened to increase the roughness of the interface between the new and old concrete. The new concrete 2 is natural aggregate concrete or recycled aggregate concrete with a maximum coarse aggregate size of no more than 20 mm, or concrete containing engineering debris. Recycled aggregate concrete with recycled sand; vertical through holes 8 are provided on the old concrete slab 1, and steel bar insertions 5 are inserted into the through holes 8; the gaps between the through holes 8 and the steel bar insertions 5 are filled with high-strength grouting material, and the steel bar insertions 5 can further enhance the shear resistance of the interface between the new and old concrete; the slab surface steel mesh 4 is located above the old concrete slab 1; the internal upper longitudinal steel bars of the old concrete slab 1 are connected to the longitudinal steel bars of the slab surface steel mesh 4; the corrugated steel plate 7 is located below the old concrete slab 1, and the longitudinal stress-bearing steel bars 10 and the transverse distribution bars 11 at the bottom of the slab are arranged on the corrugated steel plate 7; new concrete 2 is poured on the top, bottom and surrounding areas of the old concrete slab 1.

[0047] In some embodiments of the present invention, the corrugated steel plate composite floor directly utilizing the old concrete slab has a width of 750 mm, a length of 3000 mm, and a thickness of 150 mm.

[0048] In some embodiments of the present invention, the compressive strength of the new concrete 2 is 30 MPa, and the compressive strength of the old concrete slab 1 is 25 MPa.

[0049] In some embodiments of the present invention, an open corrugated steel plate 7 is used, and the steel plate model is YX35-125-750. In some embodiments of the present invention, longitudinal stress-bearing ribs 10 and transverse distribution ribs 11 are arranged at the bottom of the corrugated steel plate.

[0050] In some embodiments of the present invention, the plate surface steel mesh 4 is formed by binding steel bars along the span direction and along the width direction, with the reinforcement C10@200 along the span direction and the reinforcement C8@200 along the width direction.

[0051] The above-mentioned construction method of a corrugated steel plate composite floor slab directly utilizing old concrete slabs comprises the following steps:

[0052] (1) Arrange the longitudinal stress-bearing steel bars 10 and the transverse distribution bars 11 on the bottom of the corrugated steel plate 7;

[0053] (2) Drill a through hole 8 on the old concrete slab 1, insert the steel bar 5 into the through hole 8 and fill the gap between the two with high-strength grouting material;

[0054] (3) Pour a layer of new concrete 2 into the casting mold. The height of this layer of new concrete 2 exceeds the transverse distribution reinforcement 11 at the bottom of the slab, and vibrate and compact it.

[0055] (4) placing the old concrete slab 1 that has been fully moistened in advance directly on the layer of new concrete 2 poured in step (3), and applying a vertical downward vibration pressure for a duration of not less than 2 minutes to the upper surface of the old concrete slab 1;

[0056] (5) A slab surface reinforcement mesh 4 is laid on top of the old concrete slab 1. The slab surface reinforcement mesh 4 is locally spot-welded to the adjacent reinforcement bars 5. The upper longitudinal reinforcement of the old concrete slab 1 is welded to the longitudinal reinforcement of the slab surface reinforcement mesh 4 using pre-bent reinforcement bars. Then, sufficient new concrete 2 is poured into the casting mold, vibrated sufficiently, and cured.

[0057] Traditionally, old concrete slabs have been first crushed, their internal steel bars removed and sold, and then the crushed large blocks of concrete are directly used as recycled blocks, or the large blocks of concrete are further crushed multiple times to be refined into recycled aggregate for use. Whether using recycled blocks to prepare recycled block concrete or using recycled aggregate to prepare recycled aggregate concrete, a large amount of fresh cement and other cementitious materials are required. Cement production not only consumes a lot of energy but also emits huge carbon emissions. On the other hand, a large amount of powder that is difficult to use is inevitably produced during the multiple crushing processes, which significantly reduces the recycling rate of the old concrete. To solve the above problems, the present invention proposes for the first time the idea of ​​directly recycling old concrete slabs at the component level, instead of crushing them into recycled blocks or recycled aggregates. This not only greatly simplifies the processing process, but also avoids the output of powder. More importantly, it can significantly reduce the amount of new concrete and the corresponding fresh cement used, with significant energy-saving and carbon-reducing effects. Previously, there were no reports internationally on the direct recycling of old concrete slabs in new components.

[0058] According to the present invention, the rebar inside the old concrete slab is no longer removed and sold, which appears to reduce economic income to a certain extent. This is also the main reason why previous researchers had difficulty in conceiving of directly recycling old concrete slabs. However, considering the savings in equipment and labor costs associated with crushing the old concrete slabs and removing the rebar, the avoidance of large amounts of waste material transportation and dumping expenses, and the cost savings resulting from the significant reduction in new concrete and corresponding fresh cement consumption brought about by the direct recycling of old concrete slabs in new components, the present invention still has good overall economic benefits. At the same time, the internal rebar of the old concrete slab can also provide a certain amount of support during the service life of the new component, thereby reducing the reinforcement requirements of the new component, which undoubtedly makes the present invention more advantageous.

[0059] 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. Directly utilize the prefabricated floor slabs of old concrete slabs, characterized by: It includes an old concrete slab (1), new concrete (2), a slab bottom reinforcement mesh (3), a slab surface reinforcement mesh (4), reinforcement rods (5) and an overhanging rack (6); The length and width of the old concrete slab (1) are respectively smaller than the length and width of the precast floor slab, and the volume of the old concrete slab (1) is not less than 50% of the volume of the precast floor slab; New concrete (2) is natural aggregate concrete or recycled aggregate concrete with a maximum coarse aggregate size of not more than 20 mm, or recycled aggregate concrete containing recycled sand from construction waste; A through hole (8) is vertically drilled on the old concrete slab (1), and a steel bar insert (5) is inserted into the through hole (8); a gap between the through hole (8) and the steel bar insert (5) is filled with a high-strength grouting material; The bottom steel mesh (3) and the surface steel mesh (4) are respectively located below and above the old concrete slab (1); the internal upper longitudinal steel bars of the old concrete slab (1) are connected to the longitudinal steel bars of the surface steel mesh (4); The overhanging rack (6) is located on the side wall of the precast floor slab, a steel component (9) is inserted into the overhanging rack (6), and the steel component (9) extends into the main body of the precast floor slab in the reverse direction; new concrete (2) is poured on the upper, lower and surrounding areas of the old concrete slab (1) and inside the overhanging rack (6).

2. The prefabricated floor slab directly utilizing old concrete slabs according to claim 1, characterized in that: The steel component (9) extends in the reverse direction into the main body of the prefabricated floor slab by not less than 50 mm, and the steel component (9) is a steel bar or angle steel or I-shaped steel with a yield strength of not less than 235 MPa.

3. Directly utilize the corrugated steel plate composite floor of the old concrete slab, which is characterized by: It includes old concrete slab (1), new concrete (2), slab surface steel mesh (4), steel bar inserts (5), profiled steel plate (7), slab bottom longitudinal stress-bearing steel bars (10) and slab bottom transverse distribution bars (11); The length and width of the old concrete slab (1) are respectively smaller than the length and width of the corrugated steel plate composite floor slab; New concrete (2) is natural aggregate concrete or recycled aggregate concrete with a maximum coarse aggregate size of not more than 20 mm, or recycled aggregate concrete containing recycled sand from construction waste; A through hole (8) is drilled vertically on the old concrete slab (1), a steel bar insert (5) is inserted into the through hole (8), and a gap between the through hole (8) and the steel bar insert (5) is filled with a high-strength grouting material; The slab surface reinforcement mesh (4) is located above the old concrete slab (1); the internal upper longitudinal reinforcement of the old concrete slab (1) is connected to the longitudinal reinforcement of the slab surface reinforcement mesh (4); The corrugated steel plate (7) is located below the old concrete plate (1), and longitudinal stress-bearing steel bars (10) and transverse distribution bars (11) at the bottom of the plate are arranged on the corrugated steel plate (7); new concrete (2) is poured above, below and around the old concrete plate (1).

4. The floor slab according to any one of claims 1 to 3, characterized in that: The length and width of the old concrete slab (1) are at least 80 mm smaller than the length and width of the prefabricated floor slab or the corrugated steel plate composite floor slab.

5. The floor slab according to any one of claims 1 to 3, characterized in that: The upper and lower surfaces of the old concrete slab (1) are each cut to a thickness of 5-20 mm and roughened.

6. The floor slab according to any one of claims 1 to 3, characterized in that: The old concrete slab (1) is a concrete slab produced by demolishing old buildings or structures.

7. The floor slab according to any one of claims 1 to 3, characterized in that: The compressive strength of the new concrete (2) is not lower than the concrete compressive strength of the old concrete slab (1).

8. The floor slab according to any one of claims 1 to 3, characterized in that: The length of the steel bar insert (5) is greater than the original thickness of the old concrete slab (1) by 10-30 mm and is not greater than the thickness of the prefabricated floor slab or the corrugated steel plate composite floor slab.

9. A construction method for prefabricated floor slabs directly utilizing old concrete slabs, characterized in that: The following steps are involved: (1) Tie the bottom steel mesh (3) and the surface steel mesh (4) and place the bottom steel mesh (3) above the bottom formwork; and arrange a protective layer pad between the bottom steel mesh (3) and the bottom formwork; (2) drilling a through hole (8) vertically on the old concrete slab (1), inserting the steel bar (5) into the through hole (8) and filling the gap between the two with high-strength grouting material; (3) inserting a steel component (9) into the extended rack (6), and the steel component (9) extends into the main body of the prefabricated floor in the reverse direction; (4) pouring a layer of new concrete (2) into the casting mold, the height of this layer of new concrete (2) exceeds the steel mesh (3) at the bottom of the slab, and vibrating and compacting it; (5) placing the old concrete slab (1) that has been fully moistened in advance directly on the layer of new concrete (2) poured in step (4), and applying a vertical downward vibration pressure on the upper surface of the old concrete slab (1) for a predetermined period of time; (6) A slab surface reinforcement mesh (4) is arranged above the old concrete slab (1), the slab surface reinforcement mesh (4) is locally spot-welded to adjacent reinforcement bars (5), and the upper longitudinal reinforcement of the old concrete slab (1) and the longitudinal reinforcement of the slab surface reinforcement mesh (4) are welded together using pre-bent reinforcement bars. Then, sufficient new concrete (2) is poured into the casting mold, fully vibrated, and cured.

10. A construction method for directly utilizing corrugated steel plates to assemble floor slabs from old concrete slabs, characterized by: The following steps are involved: (1) Arranging longitudinal stress-bearing steel bars (10) and transverse distribution bars (11) at the bottom of the corrugated steel plate (7); (2) drilling a through hole (8) on the old concrete slab (1), inserting the steel bar (5) into the through hole (8) and filling the gap between the two with high-strength grouting material; (3) pouring a layer of new concrete (2) into the casting mold, the height of this layer of new concrete (2) exceeding the transverse distribution reinforcement (11) at the bottom of the slab, and vibrating and compacting it; (4) placing the old concrete slab (1) that has been fully moistened in advance directly on the layer of new concrete (2) poured in step (3), and applying a vertical downward vibration pressure on the upper surface of the old concrete slab (1) for a predetermined period of time; (5) A slab surface reinforcement mesh (4) is arranged above the old concrete slab (1), the slab surface reinforcement mesh (4) is locally spot-welded to adjacent reinforcement bars (5), and the upper longitudinal reinforcement of the old concrete slab (1) and the longitudinal reinforcement of the slab surface reinforcement mesh (4) are welded together using pre-bent reinforcement bars. Then, sufficient new concrete (2) is poured into the casting mold, fully vibrated, and cured.

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