Functionally graded concrete composite slab and method of making

Abstract

The application relates to a functionally graded concrete composite slab and a manufacturing method thereof. The manufacturing method of the functionally graded concrete composite slab comprises the following steps: step 1), placing a steel bar mesh and a connecting piece into a mold; step 2), pouring prefabricated concrete into the mold until the steel bar mesh is buried and the connecting piece is partially exposed; step 3), vibrating the prefabricated concrete in the mold before the prefabricated concrete is semi-dried to obtain a prefabricated concrete slab with gradually increasing density from top to bottom; step 4), transporting the prefabricated concrete slab to a site and hoisting the prefabricated concrete slab into place; and step 5), binding a cast-in-place steel bar framework at the upper part of the prefabricated concrete slab and pouring cast-in-place concrete, and obtaining the functionally graded concrete composite slab after the cast-in-place concrete is dried. The application has the beneficial effects of optimizing stress, improving heat preservation effect, reducing floor thickness, saving materials and improving production efficiency.

Description

Technical Field

[0001] This invention relates to the field of construction, and more specifically to composite concrete slabs. Background Technology

[0002] Firstly, as a crucial horizontal component in building construction, floor slabs primarily bear vertical loads outside their plane, such as their own weight, furniture, goods, and personnel. However, the stress distribution along the thickness of the floor slab is uneven, with the minimum stress, almost zero, at the center, while the maximum stress is experienced at the bottom and top of the slab. However, existing precast concrete composite slabs have a uniform density throughout their precast concrete layers, resulting in no change in strength along the slab's thickness. This means the strength of the composite slab cannot be adjusted according to the location of the stress.

[0003] Furthermore, with increasingly stringent energy-saving requirements for buildings, the insulation requirements for floor slabs are also becoming more stringent. The conventional practice is to lay the insulation layer on the floor slab surface after the structural floor slab construction is completed. However, the insulation material has relatively low strength, so to protect it, a protective layer of fine aggregate concrete about 5cm thick needs to be poured on top. This increases the thickness of the floor slab, reduces the room's ceiling height, and also makes the insulation layer more susceptible to damage. Summary of the Invention

[0004] The purpose of this invention is to provide a functionally graded concrete composite slab to solve at least one of the above-mentioned technical problems.

[0005] The purpose of this invention is to provide a method for manufacturing a functionally graded concrete composite slab.

[0006] The technical problem solved by this invention can be achieved by the following technical solutions:

[0007] A functionally graded concrete composite slab includes a precast concrete slab with a steel mesh embedded within it. The precast concrete slab is characterized in that the density of the precast concrete slab gradually increases from top to bottom, and a cast-in-place concrete slab is cast above the precast concrete slab, with a cast-in-place steel reinforcement skeleton embedded within the cast-in-place concrete slab.

[0008] It also includes connectors, the bottom of which is embedded in the precast concrete slab and the top of which is embedded in the cast-in-place concrete slab.

[0009] A method for manufacturing a functionally graded concrete composite slab, characterized by comprising the following steps:

[0010] Step 1) Place the steel mesh and connectors into the mold for producing precast composite slabs;

[0011] Step 2) Pour the precast concrete into the mold until the steel mesh is buried, with the connectors partially embedded and partially exposed.

[0012] Step 3) Before the precast concrete is semi-dry, the precast concrete in the mold is vibrated, so that the denser raw materials in the precast concrete sink and the less dense raw materials rise, and then after the precast concrete is completely dry, a precast concrete slab with density gradually increasing from top to bottom is obtained.

[0013] Step 4) Transport the precast concrete slabs to the site and hoist them into place;

[0014] Step 5) Tie the cast-in-place steel reinforcement cage on the top of the precast concrete slab, pour the cast-in-place concrete, and after the cast-in-place concrete has dried, a functional gradient concrete composite slab is obtained.

[0015] The present invention has the following beneficial effects:

[0016] Stress optimization: Functionally graded concrete composite slabs optimize the stress distribution of the floor slab, allowing the material to bear appropriate stress in different parts, thereby improving the structural performance and load-bearing capacity of the floor slab.

[0017] Improved thermal insulation: The lower density upper portion of the precast concrete slab in this invention provides better thermal insulation, replacing the need for a separate insulation layer and reducing construction difficulty. More importantly, the lower density upper portion of the precast concrete slab is more evenly distributed, and its thickness can be adjusted according to insulation performance requirements. Therefore, it effectively ensures the thermal insulation performance of the floor slab, reduces the risk of insulation layer damage, and thus meets building energy conservation requirements.

[0018] Reducing floor slab thickness: The design of functionally graded concrete composite slabs minimizes stress at the center of the floor, allowing for a reduction in slab thickness and an increase in room height. This helps increase usable space in the building and enhances the user experience.

[0019] Material saving: Functionally graded concrete composite slabs allow for layer-by-layer concrete deposition, reducing material waste. During the fabrication process, the material composition is gradually altered as needed, improving material utilization and minimizing waste.

[0020] Increased production efficiency: Functionally graded concrete composite slabs can meet complex design requirements, reducing processing and adjustment work during construction and improving production efficiency. This helps to shorten the construction period and increase construction efficiency.

[0021] In summary, this invention offers several advantages, including optimized stress distribution, improved thermal insulation, reduced floor slab thickness, material savings, and increased production efficiency. These benefits make it widely applicable in the construction industry, helping to improve the structural performance, energy efficiency, and construction efficiency of buildings, and meeting evolving building needs. Detailed Implementation

[0022] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention is further described below.

[0023] The method for manufacturing functionally graded concrete composite slabs includes the following steps:

[0024] Step 1) Place the steel mesh and connectors into the mold for producing precast composite slabs;

[0025] Step 2) Pour the precast concrete into the mold until the steel mesh is buried, with the connectors partially embedded and partially exposed.

[0026] Step 3) Before the precast concrete is semi-dry, the precast concrete in the mold is vibrated, so that the denser raw materials in the precast concrete sink and the less dense raw materials rise, and then after the precast concrete is completely dry, a precast concrete slab with density gradually increasing from top to bottom is obtained.

[0027] Step 4) Transport the precast concrete slabs to the site and hoist them into place;

[0028] Step 5) Tie the cast-in-place steel reinforcement cage on the top of the precast concrete slab, pour the cast-in-place concrete, and after the cast-in-place concrete has dried, a functional gradient concrete composite slab is obtained.

[0029] The structure of the functionally graded concrete composite slab obtained by the above manufacturing method is as follows:

[0030] The functionally graded concrete composite slab includes a precast concrete slab with a density that gradually increases from top to bottom, a steel mesh embedded in the precast concrete slab, and a cast-in-place concrete slab on top of the precast concrete slab with a cast-in-place steel reinforcement skeleton embedded in the cast-in-place concrete slab; it also includes connectors, the bottom of which is embedded in the precast concrete slab and the top of which is embedded in the cast-in-place concrete slab.

[0031] In step 1), the mesh shape of the reinforcing mesh is preferably square, rectangular, or triangular. The connectors are metal or polymer connectors. The bottom of the connector is preferably welded to or tied to the reinforcing mesh. The connector preferably includes a rod-shaped main body with outwardly extending branches on its sidewalls. Openings can be added to the branches to increase the connection strength between the connector and the concrete and to prevent rotation or displacement. Preferably, the branches at the lower part of the main body extend outward and upward, while the branches at the upper part extend outward and downward. This utilizes the branches to form a hook structure, improving the connection strength between the cast-in-place concrete layer and the precast concrete layer.

[0032] In step 2), the raw materials for precast concrete include cement, aggregate, and mortar. An expanding agent may also be included, thereby further reducing the density of the upper layer of the precast concrete slab. Steel fibers may also be included. The weight percentage of steel fibers is 0.5%-2%. Preferred steel fibers are milled steel fibers from steel ingots. Steel fibers can increase the strength and toughness of the precast concrete slab. Cement, aggregate, and mortar can be mixed first to form mixture 1. Mixture 1 is then poured into a mold, and the expanding agent and steel fibers are sprayed onto the upper surface of mixture 1, followed by plate vibration. This ensures that the expanding agent and steel fibers are more concentrated in the upper layer. The raw materials for precast concrete also include water, with a water mass percentage of not less than 25% of the total mass. Cement, aggregate, and mortar can be mixed first to form mixture 1, and then mixture 1 can be mixed with water to form mixture 2. Mixture 2 is then poured into a mold, and the expanding agent and steel fibers are sprayed onto the upper surface of mixture 2, followed by plate vibration. Alternatively, cement, aggregate, mortar, water, and steel fiber can be mixed together to form mixture 3. Mixture 3 is poured into a mold, and an expanding agent is sprayed onto its upper surface before compaction with a plate vibrator. Alternatively, cement, aggregate, mortar, water, steel fiber, and expanding agent can be mixed together to form mixture 4. Mixture 4 is poured into a mold and then compacted with a plate vibrator. This invention increases the amount of water used, which gives the mixture higher fluidity, resulting in less resistance to movement of the raw materials during compaction and easier movement. The mold preferably includes a base plate and side plates surrounding the outer edge of the base plate. An overflow port can be provided on the side plates, and a plug is provided on the overflow port. After compaction, the mixture is allowed to stand for a period of time, and then the plug is removed to allow excess water to flow out from the overflow port. The overflow port is preferably an upward-facing notch, and multiple plugs are preferably provided, each with a different height. This allows for adjustment based on the varying heights of the precast concrete within the mold, utilizing the structure of the notch and the height of the plugs. The side plate of the present invention is taller than the existing mold, thereby better holding the precast concrete and providing space for vibration stratification of the precast concrete.

[0033] In step 3), the precast concrete within the mold can be vibrated by compacting the precast concrete. Flat plate vibration is particularly preferred. This invention utilizes the movement of different density components under vibration force in the fluid state of the concrete, gradually changing the composition of one material to another along the thickness of the slab, creating a change in properties based on the thickness direction, thereby meeting the material requirements of different functional parts. The intensity and duration of vibration can be adjusted as needed to adjust the density at various points. The thickness of the precast concrete slab is preferably 3cm-10cm. The side panels can be partially or completely transparent, forming observation windows. Through these windows, the position of the raw materials in the precast concrete can be observed, allowing for judgment of the density gradient change along the thickness direction of the final precast concrete slab based on the positional changes or current position of the raw materials. Besides using vibration to cause stratification of the precast concrete within the mold, an ultrasonic device can also be added to the mold to induce stratification, or the mold can be placed on a vibration device, with the vibration of the mold causing the precast concrete within the mold to stratify.

[0034] In step 5), the cast-in-place reinforcing steel cage is preferably a reinforcing steel mesh, and the mesh shape of the reinforcing steel mesh is preferably a square mesh, a rectangular mesh, or a triangular mesh. The top of the connector is preferably welded or tied to the cast-in-place reinforcing steel cage.

[0035] Following step 5), step 6) can be added: plastering the lower surface of the functionally graded concrete composite slab and applying a surface layer to the upper surface of the slab. The surface layer application includes paint, tiles, etc.

[0036] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a functionally graded concrete composite slab, characterized in that, Includes the following steps: Step 1) Place the steel mesh and connectors into the mold for producing precast composite slabs; Step 2) Pour the precast concrete into the mold until the steel mesh is buried, and the connectors are partially buried and partially exposed. The raw materials of the precast concrete include cement, aggregate, mortar, expansion agent, steel fiber, and water, and the water content is not less than 25% of the total mass. Step 3) Before the precast concrete is semi-dry, the precast concrete in the mold is vibrated, so that the denser raw materials in the precast concrete sink and the less dense raw materials rise, and then after the precast concrete is completely dry, a precast concrete slab with density gradually increasing from top to bottom is obtained. Step 4) Transport the precast concrete slabs to the site and hoist them into place; Step 5) Tie the cast-in-place steel reinforcement cage on the top of the precast concrete slab, pour the cast-in-place concrete, and after the cast-in-place concrete has dried, a functional gradient concrete composite slab is obtained. The bottom of the connector is welded or tied to a steel mesh, and the top of the connector is welded or tied to a cast-in-place steel skeleton. The connector includes a rod-shaped main body with outwardly extending branches on the side wall of the main body. The branches are provided with openings. The branches connected to the lower part of the main body extend outward and upward, and the branches located at the upper part extend outward and downward.

2. The method for manufacturing a functionally graded concrete composite slab according to claim 1, characterized in that, In step 3), the precast concrete inside the mold is vibrated by vibrating the precast concrete.

3. The method for manufacturing a functionally graded concrete composite slab according to claim 2, characterized in that, The vibration is performed using a flat plate.

4. The method for manufacturing a functionally graded concrete composite slab according to claim 1, characterized in that, In step 3), the mold is placed on the vibration device, and the vibration of the mold causes the precast concrete inside the mold to vibrate and layer.

5. The method for manufacturing a functionally graded concrete composite slab according to claim 1, characterized in that, Step 6) Apply plaster to the lower surface of the functional gradient concrete composite slab and apply a surface layer to the upper surface of the functional gradient concrete composite slab.

6. The functionally graded concrete composite slab prepared by the method of manufacturing a functionally graded concrete composite slab according to any one of claims 1-5, comprising a precast concrete slab, wherein a reinforcing mesh is embedded in the precast concrete slab, characterized in that, The density of the precast concrete slab gradually increases from top to bottom. A cast-in-place concrete slab is cast on top of the precast concrete slab, and a cast-in-place steel reinforcement skeleton is embedded in the cast-in-place concrete slab. It also includes connectors, the bottom of which is embedded in the precast concrete slab and the top of which is embedded in the cast-in-place concrete slab. The bottom of the connector is welded or tied to a steel mesh, and the top of the connector is welded or tied to a cast-in-place steel skeleton. The connector includes a rod-shaped main body with outwardly extending branches on the side wall of the main body. The branches are provided with openings. The branches connected to the lower part of the main body extend outward and upward, and the branches located at the upper part extend outward and downward.

7. The functionally graded concrete composite slab according to claim 6, characterized in that, The thickness of precast concrete slabs is 3cm-10cm.