Large-span composite laminated floor and construction method of the floor

Abstract

The invention relates to a large-span composite composite floor slab and a construction method of the floor slab, belonging to the field of building technology, comprising a prefabricated composite base plate, a plurality of autoclaved aerated concrete blocks are vertically embedded on the prefabricated composite base plate at equal intervals along the length direction of the prefabricated composite base plate, a reinforcement cage is arranged on the outer side of the autoclaved aerated concrete block in the transverse direction and the longitudinal direction respectively, the reinforcement cage is abutted against the autoclaved aerated concrete block, the reinforcement cage is connected to the prefabricated composite base plate, and a post-cast concrete superimposed layer is cast on the autoclaved aerated concrete block and the reinforcement cage. The invention adopts the autoclaved aerated concrete block as the built-in lightweight core material, utilizes the good contact and friction performance of the autoclaved aerated concrete block and concrete, improves the compatibility of the core material and concrete, and the reinforcement cage limits the autoclaved aerated concrete block to avoid floating and shifting of the autoclaved aerated concrete block when casting the post-cast concrete superimposed layer, thereby ensuring the force transmission performance and working performance of the superimposed floor slab.

Description

Technical Field

[0001] The invention belongs to the technical field of construction, and in particular relates to a large-span composite laminated floor slab and a construction method of the floor slab. Background Art

[0002] With the development of my country's economy, people's requirements for lifestyle and living functions have increased, and large-span (6~7m) civil buildings have developed rapidly. The key to realizing flexible large-span housing is the research and development of floor systems. If large-span composite floor slabs are still manufactured using solid plate components similar to cast-in-place slab structures, the surface area and self-weight of the prefabricated bottom slab will inevitably be large, which will not only cause certain difficulties in the transportation of prefabricated components, but also bring a series of challenges to the hoisting equipment and temporary support systems at the construction site. Therefore, the development of a new large-span composite floor slab system with light self-weight, good overall performance, and convenient industrial production and assembly construction has become an urgent problem to be solved in the research of composite floor slabs.

[0003] At present, the existing technology mainly uses sandwich panels and hollow panels with built-in lightweight core materials to form hollows or cavities in the floor slabs. The use of lightweight core materials can greatly reduce the self-weight of the composite floor slabs. Since the above-mentioned sandwich panels and hollow panels have the advantages of light self-weight and high rigidity, they are excellent structural forms for realizing large-span floor slabs. However, concrete composite floor slabs are a combination of prefabrication and cast-in-place processes. After multiple concrete composite floor slabs are flatly installed, a layer of concrete needs to be cast on their surface. When the composite floor slab is constructed using sandwich panels and hollow panels with advantages such as light self-weight and high rigidity, the interior of the composite floor slab can have a certain hollow ratio. However, since the core materials generally use EPS, XPS and other materials, the compatibility between the core materials and concrete is relatively weak, resulting in poor force transmission performance of the post-cast concrete overlapping surface. At the same time, the core material is prone to floating and shifting due to its light weight during pouring, resulting in poor shear resistance of the composite floor slab and the post-cast concrete overlapping surface and poor force transmission performance of the composite floor slab. Summary of the invention

[0004] In view of this, the present invention provides a large-span composite composite floor and a construction method of the floor, which can effectively reduce the deadweight of the composite floor while ensuring the force transmission performance and working performance of the composite floor, so as to solve the deficiencies in the prior art.

[0005] The technical solution of the present invention is: a large-span composite composite floor slab, comprising a prefabricated composite base plate, a plurality of autoclaved aerated concrete blocks are vertically embedded on the prefabricated composite base plate at equal intervals along the length direction of the prefabricated composite base plate, reinforcement cages are arranged on the outer sides of the autoclaved aerated concrete blocks in the transverse and longitudinal directions respectively, the reinforcement cages are abutted against the autoclaved aerated concrete blocks, the transverse and longitudinal reinforcement cages are connected to each other, the reinforcement cages are connected to the prefabricated composite base plate, a post-cast concrete superimposed layer is cast on the autoclaved aerated concrete blocks and the reinforcement cages, the post-cast concrete superimposed layer is connected to the prefabricated composite base plate, the autoclaved aerated concrete blocks and the reinforcement cages, and the thickness of the prefabricated composite base plate is half the height of the autoclaved aerated concrete blocks.

[0006] Preferably, the autoclaved aerated concrete blocks are located in the middle of the prefabricated composite floor in the width direction.

[0007] Preferably, an underlying ultra-high performance concrete liner is cast on one side of the prefabricated composite bottom plate away from the post-cast concrete superposition layer, and the autoclaved aerated concrete blocks pass through the prefabricated composite bottom plate and abut against the underlying ultra-high performance concrete liner.

[0008] Preferably, the prefabricated composite bottom plate includes: a prefabricated composite bottom plate steel mesh and concrete cast on the prefabricated composite bottom plate steel mesh, the prefabricated composite bottom plate steel mesh is composed of bottom longitudinal stress-bearing steel bars and bottom transverse stress-bearing steel bars arranged at equal intervals in the longitudinal and transverse directions, which are connected to each other, the bottom longitudinal stress-bearing steel bars and the bottom transverse stress-bearing steel bars are located on the outside of the autoclaved aerated concrete blocks, and the bottom longitudinal stress-bearing steel bars and the bottom transverse stress-bearing steel bars are respectively connected to the reinforcement cage.

[0009] Preferably, the reinforcement cage is abutted against the underlying ultra-high performance concrete liner, the bottom longitudinal stress-bearing steel bars and the bottom transverse stress-bearing steel bars are respectively passed through the reinforcement cage, and the bottom longitudinal stress-bearing steel bars and the bottom transverse stress-bearing steel bars are respectively fixedly connected to the inner bottom of the reinforcement cage.

[0010] Preferably, the post-cast concrete overlap layer includes: a post-cast concrete overlap layer steel mesh and concrete cast on the cast concrete overlap layer steel mesh, the post-cast concrete overlap layer steel mesh is composed of top longitudinal stress-bearing steel bars and top transverse stress-bearing steel bars arranged at equal intervals in the longitudinal and transverse directions, which are connected to each other, the top longitudinal stress-bearing steel bars and the top transverse stress-bearing steel bars are located on the outside of the autoclaved aerated concrete blocks, and the top longitudinal stress-bearing steel bars and the top transverse stress-bearing steel bars are connected to the reinforcement cage.

[0011] Preferably, the top longitudinal stress-bearing steel bars and the top transverse stress-bearing steel bars are respectively passed through the reinforcement cage, and the top longitudinal stress-bearing steel bars and the top transverse stress-bearing steel bars are fixedly connected to the inner top of the reinforcement cage.

[0012] Preferably, longitudinal stress-bearing steel bars in intercostal thin plates and transverse stress-bearing steel bars in intercostal thin plates are arranged at equal intervals in the longitudinal and transverse directions directly above the autoclaved aerated concrete blocks, the longitudinal stress-bearing steel bars in the intercostal thin plates and the transverse stress-bearing steel bars in the intercostal thin plates are connected to each other, and the longitudinal stress-bearing steel bars in the intercostal thin plates and the transverse stress-bearing steel bars in the intercostal thin plates are respectively connected to the top longitudinal stress-bearing steel bars and the top transverse stress-bearing steel bars.

[0013] Preferably, the reinforcement cage includes: a transverse rib inner reinforcement cage and a longitudinal rib inner reinforcement cage, which are respectively arranged on the outside of the autoclaved aerated concrete block in the transverse and longitudinal directions, and are respectively parallel to the width and length of the prefabricated composite base plate.

[0014] A construction method for a large-span composite laminated floor slab comprises the following steps:

[0015] Step 1: Make a lower ultra-high performance concrete liner, support and place the side steel formwork according to the width and length of the lower ultra-high performance concrete liner, and pour the prepared UHPC material in the side steel formwork;

[0016] Step 2: Make a prefabricated composite floor. When the strength of the UHPC material in "Step 1" reaches 100%, place the side formwork of the prefabricated composite floor around it, place the autoclaved aerated concrete blocks that have been soaked for 24 hours at the designated position, put the prefabricated composite floor steel mesh and the tied reinforcement cage in the gap area outside the autoclaved aerated concrete blocks, and then pour concrete;

[0017] Step 3: Make the post-cast concrete superimposed layer. After the concrete strength in "Step 2" reaches 75%, support the side formwork of the post-cast concrete superimposed layer, place the post-cast concrete superimposed layer steel mesh and then pour concrete. When the concrete strength reaches 100%, a large-span composite superimposed floor is obtained.

[0018] Compared with the prior art, the present invention provides a large-span composite composite floor and a construction method of the floor. The composite composite floor is formed by combining a prefabricated composite base plate, autoclaved aerated concrete blocks, a reinforcement cage and a post-cast concrete superimposed layer. The autoclaved aerated concrete blocks are used as built-in lightweight core materials to effectively reduce the deadweight of the composite floor. The good contact and friction performance between the autoclaved aerated concrete blocks and concrete is utilized to improve the compatibility between the core material and the concrete. At the same time, the reinforcement cage limits the autoclaved aerated concrete blocks to avoid floating and shifting of the autoclaved aerated concrete blocks when pouring the post-cast concrete superimposed layer. The reinforcement cage can effectively ensure the shear resistance of the prefabricated composite base plate and the post-cast concrete superimposed surface, so that the composite floor presents good beam-type force characteristics, ensuring the force transmission performance and working performance of the composite floor. The composite floor of the present invention has good effect, is easy to use, has strong practicality, and is worthy of promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a stereogram of the present invention;

[0020] Figure 2 It is a schematic diagram of the prefabricated composite bottom plate steel mesh of the present invention;

[0021] Figure 3 It is a schematic diagram of a post-cast concrete laminated layer steel mesh of the present invention;

[0022] Figure 4 is a side half-section view of the present invention;

[0023] Figure 5 is an AA cross-sectional view of the present invention;

[0024] Figure 6 It is the BB cross-sectional view of the present invention;

[0025] Figure 7 It is a top view of the post-cast concrete superimposed layer steel mesh of the present invention. DETAILED DESCRIPTION

[0026] The present invention provides a large-span composite laminated floor and a construction method of the floor. Figures 1 to 7 The present invention is described with reference to the structural schematic diagram of FIG.

[0027] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the technical solutions of the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0028] As shown in the figure, Figure 1 This is a three-dimensional diagram of this embodiment, a large-span composite composite floor, including a prefabricated composite bottom plate 2, as shown in the figure, Figure 4It is a side half-section view of the present embodiment, a plurality of autoclaved aerated concrete blocks 4 are vertically embedded in the prefabricated composite base plate 2 at equal intervals along the length direction of the prefabricated composite base plate 2, the autoclaved aerated concrete blocks 4 are connected to the prefabricated composite base plate 2, the reinforcement cages 11 are arranged on the outside of the autoclaved aerated concrete blocks 4 in the transverse and longitudinal directions respectively, the reinforcement cages 11 are abutted against the autoclaved aerated concrete blocks 4, the transverse and longitudinal reinforcement cages 11 are connected to each other, the reinforcement cages 11 are connected to the prefabricated composite base plate 2, the post-cast concrete superimposed layer 3 is cast on the autoclaved aerated concrete blocks 4 and the reinforcement cages 11, the post-cast concrete superimposed layer 3 is connected to the prefabricated composite base plate 2, the autoclaved aerated concrete blocks 4 and the reinforcement cages 11, and the thickness of the prefabricated composite base plate 2 is half of the height of the autoclaved aerated concrete blocks 4.

[0029] This embodiment uses autoclaved aerated concrete blocks 4, which have good contact and friction properties with concrete, to avoid the problem of poor compatibility between the core material and concrete. Due to the presence of the reinforcement cage 11 between the autoclaved aerated concrete blocks 4, the autoclaved aerated concrete blocks 4 and the top and bottom stress-bearing steel bars can be effectively fixed and restrained, and the reinforcement cage 11 is finally anchored in the prefabricated composite bottom plate 2 and the post-cast concrete superimposed layer 3, which can also effectively enhance the overall working performance of the superimposed floor slab formed by the two.

[0030] Compared with the lightweight core materials commonly used in sandwich panels and hollow panels (lightweight foam materials mainly based on polystyrene, lightweight high-strength fiber composite materials mainly based on GBF and GRC, and solid block materials mainly based on hollow bricks and aerated blocks), autoclaved aerated concrete blocks 4 are not only light in weight, but also, as conventional building maintenance materials, have the advantages of being corrosion-resistant and able to withstand local loads.

[0031] Preferably, the autoclaved aerated concrete block 4 is located in the middle of the prefabricated composite floor slab 2 in the width direction.

[0032] The composite floor slab uses autoclaved aerated concrete blocks 4 as built-in lightweight core materials, and arranges them in the parts with small bending stress near the neutral axis of the prefabricated composite bottom plate 2. Finally, the autoclaved aerated concrete blocks 4 are fixed in the prefabricated composite bottom plate 2 produced by industrialization to form a prefabricated composite floor slab. Compared with the solid ordinary concrete composite floor slab of the same span, the self-weight of the components is effectively reduced, and the requirements for the transportation of the prefabricated composite bottom plate 2 in the composite floor slab and the hoisting equipment on the construction site are reduced.

[0033] Preferably, an underlying ultra-high performance concrete liner 1 is cast on a side of the prefabricated composite base plate 2 away from the post-cast concrete superposition layer 3, and the autoclaved aerated concrete blocks 4 pass through the prefabricated composite base plate 2 and abut against the underlying ultra-high performance concrete liner 1.

[0034] The bottom of the composite floor slab of the present invention adopts ultra-high performance concrete (UHPC) as a lining plate, which effectively suppresses the cracking and peeling of the autoclaved aerated concrete blocks 4 during the bending process of the composite floor slab, thereby improving the bearing capacity of the composite floor slab.

[0035] The lower ultra-high performance concrete liner 1 is placed at the bottom of the composite floor, mainly used to enhance the tensile performance of the bottom of the floor and prevent the core material (autoclaved aerated concrete block 4) from cracking and falling off during the bending process of the composite floor. UHPC adopts UC120 grade, in which: the steel fiber adopts shear type, with a length of about 15mm and a volume ratio of 0.75%; the cement adopts silicate 42.5PII type; in quartz sand: the coarse sand particle size is 0.6-1.30mm, the medium sand particle size is 0.3-0.6mm, and the fine sand particle size is 0.16-0.3mm; the SiO2 content in silica fume is not less than 95%, and the particle size is less than 0.2μm; the water reducer adopts polycarboxylic acid water reducer.

[0036] As shown in the figure, Figure 2 This is a schematic diagram of the prefabricated composite bottom plate steel mesh of the present embodiment. Preferably, the prefabricated composite bottom plate 2 includes: a prefabricated composite bottom plate steel mesh and concrete cast on the prefabricated composite bottom plate steel mesh. The prefabricated composite bottom plate steel mesh is composed of bottom longitudinal stress-bearing steel bars 9 and bottom transverse stress-bearing steel bars 10 arranged at equal intervals in the longitudinal and transverse directions, which are connected to each other. The bottom longitudinal stress-bearing steel bars 9 and bottom transverse stress-bearing steel bars 10 are located on the outside of the autoclaved aerated concrete blocks 4, and the bottom longitudinal stress-bearing steel bars 9 and bottom transverse stress-bearing steel bars 10 are respectively connected to the reinforcement cage 11.

[0037] The prefabricated composite bottom plate 2 is located on the upper side of the lower ultra-high performance concrete liner 1, and mainly includes: A3.5 grade autoclaved aerated concrete blocks 4 (size specification: 150 mm×300mm×600mm), which are directly placed on the upper part of the lower ultra-high performance concrete liner 1; C30 grade ordinary concrete: the prefabricated composite bottom plate steel mesh and reinforcement cage 11 are configured therein, and are located between the 4 autoclaved aerated concrete blocks on the upper part of the lower ultra-high performance concrete liner 1. After the concrete pouring of the post-cast concrete superposition layer 3 is completed, the reinforced concrete transverse ribs 13 and longitudinal ribs 14 with smaller cross-sections are formed.

[0038] As shown in the figure, Figure 6 It is the BB cross-sectional view of this embodiment. Preferably, the reinforcement cage 11 is in contact with the underlying ultra-high performance concrete liner 1, the bottom longitudinal stress-bearing steel bars 9 and the bottom transverse stress-bearing steel bars 10 are respectively passed through the reinforcement cage 11, and the bottom longitudinal stress-bearing steel bars 9 and the bottom transverse stress-bearing steel bars 10 are respectively fixedly connected to the inner bottom of the reinforcement cage 11.

[0039] As shown in the figure, Figure 3This is a schematic diagram of the post-cast concrete overlap layer steel mesh of this embodiment. Preferably, the post-cast concrete overlap layer 3 includes: a post-cast concrete overlap layer steel mesh and concrete cast on the cast concrete overlap layer steel mesh. The post-cast concrete overlap layer steel mesh is composed of top longitudinal stress-bearing steel bars 5 and top transverse stress-bearing steel bars 6 that are arranged at equal intervals in the longitudinal and transverse directions and are connected to each other. The top longitudinal stress-bearing steel bars 5 and top transverse stress-bearing steel bars 6 are located on the outside of the autoclaved aerated concrete blocks 4, and the top longitudinal stress-bearing steel bars 5 and top transverse stress-bearing steel bars 6 are connected to the reinforcement cage 11.

[0040] Preferably, the top longitudinal stress-bearing steel bars 5 and the top transverse stress-bearing steel bars 6 are respectively passed through the reinforcement cage 11 , and the top longitudinal stress-bearing steel bars 5 and the top transverse stress-bearing steel bars 6 are fixedly connected to the inner top of the reinforcement cage 11 .

[0041] As shown in the figure, Figure 5 It is the AA cross-sectional view of the present embodiment. Preferably, the longitudinal stress-bearing steel bars 7 in the intercostal thin plates and the transverse stress-bearing steel bars 8 in the intercostal thin plates are arranged at equal intervals in the longitudinal and transverse directions directly above the autoclaved aerated concrete blocks 4. The longitudinal stress-bearing steel bars 7 in the intercostal thin plates and the transverse stress-bearing steel bars 8 in the intercostal thin plates are connected to each other, and the longitudinal stress-bearing steel bars 7 in the intercostal thin plates and the transverse stress-bearing steel bars 8 in the intercostal thin plates are respectively connected to the top longitudinal stress-bearing steel bars 5 and the top transverse stress-bearing steel bars 6.

[0042] Strength steel bars (including: top longitudinal stress steel bars 5, top transverse stress steel bars 6; longitudinal stress steel bars 7 in the intercostal thin plates, transverse stress steel bars 8 in the intercostal thin plates) are laid in the top post-cast layer and concrete is poured, eventually forming a bending member formed by the underlying ultra-high performance concrete liner 1, the internal autoclaved aerated concrete blocks 4 and smaller reinforced concrete ribs.

[0043] Preferably, the reinforcement cage 11 includes: a transverse rib inner reinforcement cage 111 and a longitudinal rib inner reinforcement cage 112. The transverse rib inner reinforcement cage 111 and the longitudinal rib inner reinforcement cage 112 are respectively arranged on the outside of the autoclaved aerated concrete block 4 in the transverse and longitudinal directions, and the transverse rib inner reinforcement cage 111 and the longitudinal rib inner reinforcement cage 112 are respectively parallel to the width and length of the prefabricated composite base plate 2.

[0044] Replacing the truss steel bars commonly used in existing composite floors with a smaller reinforcement cage 11 not only facilitates the arrangement of electrical pipelines in the prefabricated composite base plate 2, but also connects the reinforcement cage 11 with the top longitudinal stress-bearing steel bars 5, the top transverse stress-bearing steel bars 6, the bottom longitudinal stress-bearing steel bars 9, and the bottom transverse stress-bearing steel bars 10 to form a reinforcement skeleton. While effectively ensuring the shear resistance of the composite surface, this type of composite floor presents good beam-type stress characteristics, optimizes the configuration form and quantity of steel bars in the composite floor, and greatly improves the industrialized construction efficiency of prefabricated buildings.

[0045] The construction method of a large-span composite composite floor slab comprises the following steps:

[0046] Step 1: Prepare the lower ultra-high performance concrete liner 1, support the side steel formwork according to the width and length of the lower ultra-high performance concrete liner 1, and pour the prepared UHPC material in the side steel formwork;

[0047] Among them, when implementing step 1: first, it is necessary to clean and clean the steel structure formwork, and then support the side steel formwork according to the width and length of the lower ultra-high performance concrete liner 1 (the thickness of the UHPC liner is 20mm); apply concrete release agent; after all the work is confirmed to be correct, pour the prepared UHPC material; use a wooden sawtooth brush to artificially roughen the surface of the exposed UHPC material to meet the rough surface requirements of "concave and convex surface difference ≥ 4mm" stipulated in Article 9.5.2 of the "Concrete Structure Design Code";

[0048] Step 2: Make a prefabricated composite bottom plate 2. When the strength of the UHPC material in "Step 1" reaches 100%, place the side formwork of the prefabricated composite bottom plate 2 around it, place the autoclaved aerated concrete blocks 4 after soaking for 24 hours at the designated position, put the prefabricated composite bottom plate steel mesh and the tied reinforcement cage 11 in the gap area outside the autoclaved aerated concrete blocks 4, and then pour concrete;

[0049] Among them, when the step 2 is implemented specifically: after the bottom UHPC material reaches 100% strength, the side formwork of the prefabricated composite bottom plate 2 is placed around it according to the design size of the drawing, and the concrete release agent is brushed inside it; the autoclaved aerated concrete block 4 after soaking for 24 hours is placed in the designated design position, and the bottom of the autoclaved aerated concrete block 4 is bonded to the lower ultra-high performance concrete liner 1 with a 5mm thick bonding mortar, and the autoclaved aerated concrete block 4 is tapped with a rubber hammer to keep the top surface height consistent; the prefabricated composite bottom plate steel mesh and the tied reinforcement cage 11 (bottom longitudinal stress-bearing steel bars 9, bottom transverse stress-bearing steel bars 10 and reinforcement cage 11) are placed in the area between the gaps between the autoclaved aerated concrete blocks 4; after the above confirmation is correct, 80mm thick C30 grade concrete is poured; after the concrete is initially set, a wooden sawtooth brush is used to artificially roughen the exposed concrete surface to meet the rough surface requirement of "concave and convex surface difference ≥ 4mm" stipulated in Article 9.5.2 of the "Concrete Structure Design Code";

[0050] Step 3: Make the post-cast concrete superimposed layer 3. When the concrete strength in "Step 2" reaches 75%, support the side formwork of the post-cast concrete superimposed layer 3, place the post-cast concrete superimposed layer steel mesh, and then pour concrete. When the concrete strength reaches 100%, a large-span composite superimposed floor slab is obtained;

[0051] Among them, in step three, after the C30 grade concrete in "step two" reaches 75% of the design strength, lay the side formwork of the autoclaved aerated concrete block 4 according to the design size requirements of the drawing, and apply concrete release agent inside it; place the post-cast concrete composite layer steel mesh (the top stress-bearing steel bars in the ribs are completed together when the reinforcement cage is tied in "step two", and here only the top stress-bearing steel bars in the concrete pouring area of ​​the top of the autoclaved aerated concrete block 4 are placed), and after confirmation, pour C30 grade ordinary concrete; when the concrete strength reaches 100%, a large-span composite composite floor is formed.

[0052] When the large-span composite composite floor slab of the present invention is used, after the prepared multiple prefabricated composite bottom plates 2 are installed, concrete is poured into the post-cast concrete composite layer 3 on the upper side of the multiple prefabricated composite bottom plates 2 at one time to form the composite composite floor slab.

[0053] The above disclosure is only a preferred specific embodiment of the present invention, but the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A large-span composite composite floor slab, characterized in that: include: Prefabricated composite floor (2); A plurality of autoclaved aerated concrete blocks (4) are vertically embedded on the prefabricated composite base plate (2) at equal intervals along the length direction of the prefabricated composite base plate (2); A reinforcement cage (11) is arranged on the outside of the autoclaved aerated concrete block (4) in the transverse direction and the longitudinal direction respectively, the reinforcement cage (11) is in contact with the autoclaved aerated concrete block (4), the reinforcement cage (11) in the transverse direction and the longitudinal direction are connected to each other, and the reinforcement cage (11) is connected to the prefabricated composite bottom plate (2); A post-cast concrete superposition layer (3) is cast on the autoclaved aerated concrete blocks (4) and the reinforcement cage (11), wherein the post-cast concrete superposition layer (3) is connected to the prefabricated composite base plate (2), the autoclaved aerated concrete blocks (4) and the reinforcement cage (11); The autoclaved aerated concrete block (4) is located in the middle of the prefabricated composite base plate (2) in the width direction; A lower ultra-high performance concrete liner (1) is cast on a side of the prefabricated composite base plate (2) away from the post-cast concrete superposition layer (3), and the autoclaved aerated concrete blocks (4) pass through the prefabricated composite base plate (2) and abut against the lower ultra-high performance concrete liner (1); The thickness of the prefabricated composite base plate (2) is half the height of the autoclaved aerated concrete block (4); The prefabricated composite bottom plate (2) comprises: a prefabricated composite bottom plate steel mesh and concrete poured on the prefabricated composite bottom plate steel mesh, the prefabricated composite bottom plate steel mesh is composed of bottom longitudinal stress-bearing steel bars (9) and bottom transverse stress-bearing steel bars (10) arranged at equal intervals in the longitudinal direction and the transverse direction and connected to each other, the bottom longitudinal stress-bearing steel bars (9) and the bottom transverse stress-bearing steel bars (10) are located on the outside of the autoclaved aerated concrete blocks (4), and the bottom longitudinal stress-bearing steel bars (9) and the bottom transverse stress-bearing steel bars (10) are respectively connected to the reinforcement cage (11); The reinforcement cage (11) is in contact with the lower ultra-high performance concrete liner (1), the bottom longitudinal stress-bearing steel bars (9) and the bottom transverse stress-bearing steel bars (10) are respectively inserted into the reinforcement cage (11), and the bottom longitudinal stress-bearing steel bars (9) and the bottom transverse stress-bearing steel bars (10) are respectively fixedly connected to the inner bottom of the reinforcement cage (11); The post-cast concrete superposition layer (3) comprises: a post-cast concrete superposition layer steel mesh and concrete cast on the post-cast concrete superposition layer steel mesh, the post-cast concrete superposition layer steel mesh is composed of top longitudinal stress-bearing steel bars (5) and top transverse stress-bearing steel bars (6) arranged at equal intervals in the longitudinal direction and the transverse direction, which are connected to each other, the top longitudinal stress-bearing steel bars (5) and the top transverse stress-bearing steel bars (6) are located on the outside of the autoclaved aerated concrete block (4), and the top longitudinal stress-bearing steel bars (5) and the top transverse stress-bearing steel bars (6) are connected to the reinforcement cage (11); The top longitudinal stress-bearing steel bars (5) and the top transverse stress-bearing steel bars (6) are respectively inserted into the reinforcement cage (11), and the top longitudinal stress-bearing steel bars (5) and the top transverse stress-bearing steel bars (6) are fixedly connected to the inner top of the reinforcement cage (11); Directly above the autoclaved aerated concrete block (4), longitudinal stress-bearing steel bars (7) in the intercostal thin plates and transverse stress-bearing steel bars (8) in the intercostal thin plates are arranged at equal intervals in the longitudinal and transverse directions. The longitudinal stress-bearing steel bars (7) in the intercostal thin plates and the transverse stress-bearing steel bars (8) in the intercostal thin plates are connected to each other, and the longitudinal stress-bearing steel bars (7) in the intercostal thin plates and the transverse stress-bearing steel bars (8) in the intercostal thin plates are connected to the top longitudinal stress-bearing steel bars (5) and the top transverse stress-bearing steel bars (6), respectively. The reinforcement cage (11) comprises: a transverse rib inner reinforcement cage (111) and a longitudinal rib inner reinforcement cage (112); the transverse rib inner reinforcement cage (111) and the longitudinal rib inner reinforcement cage (112) are respectively arranged on the outside of the autoclaved aerated concrete block (4) in the transverse direction and the longitudinal direction; the transverse rib inner reinforcement cage (111) and the longitudinal rib inner reinforcement cage (112) are respectively parallel to the width and length of the prefabricated composite bottom plate (2).

2. The construction method of the large-span composite composite floor slab according to claim 1, characterized in that: The following steps are involved: Step 1: manufacturing a lower ultra-high performance concrete liner (1), placing a side steel formwork according to the width and length of the lower ultra-high performance concrete liner (1), and pouring the prepared UHPC material into the side steel formwork; Step 2: manufacturing a prefabricated composite base plate (2), when the strength of the UHPC material in "step 1" reaches 100%, placing the side formwork of the prefabricated composite base plate (2) around it, placing the autoclaved aerated concrete blocks (4) after soaking for 24 hours at a designated position, placing the prefabricated composite base plate steel mesh and the tied steel cage (11) in the gap area outside the autoclaved aerated concrete blocks (4), and then pouring concrete; Step 3: Prepare the post-cast concrete superimposed layer (3). When the concrete strength in "step 2" reaches 75%, support the side formwork of the post-cast concrete superimposed layer (3), place the post-cast concrete superimposed layer steel mesh, and then cast concrete. When the concrete strength reaches 100%, a large-span composite superimposed floor slab is obtained.

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