Manufacturing method of ECC-coal gangue concrete truss rib laminated slab

Abstract

The invention relates to the technical field of building and assembling, and discloses a manufacturing method of an ECC-coal gangue concrete truss rib laminated slab, which comprises the following steps: S1, manufacturing a reinforcing steel bar net rack, paving a plurality of orthogonal longitudinal reinforcing steel bars and transverse reinforcing steel bars on a mold table according to the specific size of the laminated slab, and arranging hooks at the tail ends of the longitudinal reinforcing steel bars and the transverse reinforcing steel bars; s2, an ECC bottom plate is poured; s3, an ECC bottom plate is installed; and S4, pouring of post-poured coal gangue concrete. According to the manufacturing method of the ECC-coal gangue concrete truss rib laminated slab, the problems that a concrete material is large in dead weight and high in density are solved, and the anti-seismic property of the structure is improved by reducing the dead weight of the laminated slab; the tension resistance of the bottom plate of the laminated slab is enhanced, the durability problem is solved, the crack resistance is improved, and the durability of the structure and the living comfort are improved; the material cost is reduced, and the economy is improved; the environmental protection property is improved and the influence on the environment is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of building assembly, and particularly to a manufacturing method of an ECC-gangue concrete truss bar composite slab. Background Art

[0002] In the field of construction engineering, as an important precast component, the composite slab is widely used in floor slabs, roof slabs and wall structures, aiming to improve construction efficiency, shorten the construction period and ensure the quality and stability of building structures. However, a series of problems have emerged in the practical application of traditional composite slabs, restricting their further promotion and optimization.

[0003] 1. Excessive self-weight, difficulties in construction and hoisting: For traditional composite slabs, such as the Chinese patent with the publication number CN222206921U, which discloses an assembled composite slab including a first casting mold, positioning insertion rods are fixedly connected to the left and right ends of the first casting mold, a first connecting plate is fixedly connected to the left and right ends of the first casting mold, a first limiting plate is fixedly connected to the top of the first casting mold, and a limiting sleeve plate is inserted into the top of the first limiting plate. In this technology, traditional ordinary concrete is used, resulting in a relatively large self-weight of the component. This not only increases the transportation difficulty and cost, but also poses higher requirements for hoisting equipment during on-site construction. Especially in high-rise buildings or complex terrains, excessive scaffolding needs to be set up, significantly increasing the construction difficulty and safety risks. In addition, the excessive self-weight may also affect the installation accuracy and efficiency of the composite slab, thereby affecting the stability and service life of the overall structure.

[0004] 2. Durability problems, frequent cracks: Although the strength and stiffness requirements are considered in the design of traditional composite slabs, under the influence of long-term load and environmental factors (such as temperature changes and humidity fluctuations), cracks are likely to occur, affecting the integrity and waterproof performance of the structure. Cracks will not only reduce the durability of the structure, but may also pose safety hazards and increase the later maintenance cost.

[0005] 3. High cost, rising material costs: With the increasing tension of natural resources, the costs of the main raw materials of traditional composite slabs, namely gravel and cementitious materials, continue to rise, posing a severe challenge to the cost control of construction projects. Especially in the context of the current global resource price fluctuations, finding alternative materials to reduce production costs has become an urgent problem in the industry.

[0006] 4. Environmental pollution and underutilization of resources: The coal gangue produced during coal mining, when piled up in large quantities, not only occupies land but may also pollute water bodies and soil through rain leaching, posing a serious environmental problem. As a potential building material, the effective utilization of coal gangue can alleviate resource shortages, reduce environmental pollution, and achieve the recycling of resources. However, in traditional laminated slab technologies, it is rare to use industrial waste such as coal gangue and fly ash as raw materials, which limits the maximization of resource utilization and the achievement of environmental protection goals. Summary of the Invention

[0007] To overcome or alleviate one or more of the above technical problems, the present invention proposes a method for fabricating an ECC-coal gangue concrete truss-bar laminated slab, which utilizes a laminated slab of ECC material and coal gangue aggregate concrete. At the same time, a new method for fabricating a two-way laminated slab is proposed to solve the problems existing in traditional laminated slabs and improve the durability, safety, and sustainability of the structure.

[0008] The present invention provides the following technical solutions:

[0009] A method for fabricating an ECC-coal gangue concrete truss-bar laminated slab, comprising the following steps:

[0010] S1. Fabrication of the steel bar grid: According to the specific dimensions of the laminated slab, lay a number of orthogonal longitudinal steel bars and transverse steel bars on the formwork table. Hooks are provided at the ends of the longitudinal steel bars and transverse steel bars. Arrange longitudinal truss bars and transverse truss bars that are orthogonal and vertically upward, or only arrange longitudinal truss bars. Both the longitudinal and transverse truss bars include multiple groups of truss bars;

[0011] S2. Pouring of the ECC bottom slab: First, pour the cementitious material and sand into the mixing pan and mix them at low speed and dry for at least 2 min. The cementitious material includes cement and fly ash. Pre-mix the weighed water reducing agent and water evenly in advance, and then slowly add them along the mixing pan and finish adding them within 1 min. Finally, slowly add PVA fibers and finish adding them within 1 min. After all the PVA fibers are added, first mix at low speed for 2 min, then mix at high speed for 3 min until the slurry is completely opened and there is no agglomeration phenomenon. The mixing process is completed within 10 min. Apply the release agent to the prepared formwork table in advance. Pour the slurry into the formwork table until it covers some of the truss bars, and then vibrate it on the vibrating table for at least 60 s. Scrape and roughen the surface of the concrete. Demold after natural curing for at least 24 h, and then place it in a standard curing room at a temperature of 20 ± 2 °C and a relative humidity of 95% for curing for at least 28 d to pour the ECC bottom slab;

[0012] S3. Installation of the ECC bottom slab: After the precast member of the ECC bottom slab is fabricated, at the construction site, after setting up the necessary supports, lay the ECC bottom slab, and fix and connect it by inserting steel bars into the adjacent hooks. Set up temporary formwork around the laminated slab;

[0013] S4. Pouring of the post-cast coal gangue concrete: After the precast ECC floor slab is installed, concrete made with coal gangue as coarse aggregate is poured above the ECC floor slab. After forming, it is cured for at least 1 day under the conditions of 20±2°C and relative humidity of 95±1%, and then demolded. The plate is cured in a standard curing room at a temperature of 20±2°C and a humidity not lower than 95% until the test age, or cured by sprinkling water until the test age, and then it is completed.

[0014] According to some embodiments, the single-group truss bars in step S1 include upper chord steel bars, lower chord steel bars, and web bars distributed in a V shape. Two web bars are fixed on the left and right sides of the upper chord steel bar, and two lower chord steel bars are respectively welded to the outer sides of the two web bars, so that the truss bars form a triangular cross-section.

[0015] According to some embodiments, the composition of the materials for making the post-cast coal gangue concrete is water, ordinary Portland cement, non-natural coal gangue, ordinary crushed stone, natural sand, and additives, and the mass ratio of each component is 1:1.87:1.7:3.96:4.62:0.0076.

[0016] According to some embodiments, the non-natural coal gangue is continuously graded coal gangue with a particle size of 4.75 - 19 mm.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. Solve the problems of large self-weight and high density of concrete materials, and improve the seismic performance of the structure by reducing the self-weight of the composite slab. The present invention proposes a composite slab using engineered cementitious composite (ECC) and coal gangue aggregate concrete. By using the high ductility and strict crack control ability of ECC materials, and the lightweight characteristics of coal gangue aggregate concrete, the purpose of reducing the self-weight of the composite slab is achieved, and the seismic performance of the structure is improved. At the same time, solve the problem of excessive weight in construction and hoisting.

[0019] 2. The present invention enhances the tensile capacity of the bottom slab of the composite slab, solves the durability problem, improves the crack resistance performance, and enhances the durability and living comfort of the structure. By using ECC materials in the composite slab, which have high ductility and strict crack control ability, the tensile capacity of the bottom slab of the composite slab can be enhanced, the appearance and development of cracks can be slowed down, and the durability and living comfort of the structure can be improved. The traditional composite slab adopts the construction method of integral splicing, and the on-site construction splicing has poor integrity and insufficient stability. This patent adopts a new form of reinforcement for the composite two-way slab, which improves the strength and stability of the overall structure, reduces splicing cracks, and avoids the adverse effects brought by on-site splicing.

[0020] 3. Reduce material costs and improve economic efficiency. The present invention uses coal gangue aggregate concrete to replace or partially replace the coarse aggregate of traditional composite slabs, effectively reducing material costs. Coal gangue aggregate is a waste resource, and using it can reduce the demand for natural crushed stone and cementitious materials, thereby reducing material costs.

[0021] 4. Improve environmental protection and reduce environmental impact. The present invention uses coal gangue aggregate concrete to replace the coarse aggregate of traditional composite slabs, reducing the use of natural resources. At the same time, by using ECC materials, the demand for traditional concrete materials can be reduced, carbon dioxide emissions can be decreased, environmental impact can be improved, and sustainable development can be promoted. Brief Description of the Drawings

[0022] Figure 1 Schematic diagram of the steel bars of the two-way slab composite slab provided in Embodiment 1 of the present invention.

[0023] Figure 2 Schematic diagram of the ECC bottom slab of the two-way slab composite slab provided in Embodiment 1 of the present invention.

[0024] Figure 3 Perspective rendering of the overall assembly of the two-way slab composite slab provided in Embodiment 1 of the present invention.

[0025] Figure 4 Schematic diagram of the steel bars of the one-way slab composite slab provided in Embodiment 2 of the present invention.

[0026] Figure 5 Schematic diagram of the ECC bottom slab of the one-way slab composite slab provided in Embodiment 2 of the present invention.

[0027] Figure 6 Perspective rendering of the overall assembly of the one-way slab composite slab provided in Embodiment 2 of the present invention.

[0028] Figure 7 Schematic diagram of the truss bars provided in the embodiments of the present invention.

[0029] In the figure:

[0030] Longitudinal steel bars 1; transverse steel bars 2; longitudinal truss bars 3; transverse truss bars 4; hooks 5; ECC bottom slab 6; upper chord steel bars 7; lower chord steel bars 8; web member steel bars 9; post-cast coal gangue concrete 10. Detailed Description of the Invention

[0031] Engineered Cementitious Composites (ECC) is a fiber-reinforced cementitious composite material with high ductility and strict crack width control. ECC is composed of all the components of traditional concrete minus the coarse aggregate, and polyvinyl alcohol fibers are added. This material has better deformation performance and durability than ordinary concrete, but there is less research on its application in composite slabs.

[0032] Coal gangue aggregate concrete is a building material that uses coal gangue to replace or partially replace coarse aggregate. Coal gangue is a solid waste generated during coal mining and coal washing. By using coal gangue, waste emissions can be effectively reduced. However, the research and application of coal gangue aggregate concrete in composite slabs are relatively few.

[0033] The present invention aims to solve the problems existing in traditional composite slabs, including but not limited to splicing cracks, uneven stress, and poor bonding performance. To solve these problems, the present invention proposes an integral form of composite slab production. In this production form, truss bars are arranged to make the stress in the slab more uniform and improve the bonding performance between the precast slab and the cast-in-place slab. Two embodiments are provided, namely a two-way slab composite slab (Embodiment 1) and a one-way slab composite slab (Embodiment 2).

[0034] The present invention will be described in detail below in conjunction with the embodiments and the drawings. However, it should be understood that the embodiments and the drawings are only used for exemplary description of the present invention and do not constitute any limitation to the protection scope of the present invention. All reasonable transformations and combinations within the scope of the inventive concept of the present invention fall within the protection scope of the present invention.

[0035] Embodiment 1

[0036] An ECC-coal gangue concrete truss bar composite slab provided in this embodiment is a two-way composite slab, and its structure is as Figures 1 to 3 , and the manufacturing method is as follows:

[0037] Step 1, manufacturing of the steel bar grid. According to the specific dimensions of the component, a number of longitudinal steel bars 1 and transverse steel bars 2 are laid on the formwork table. Both the ends of the longitudinal steel bars 1 and the transverse steel bars 2 are provided with hooks 5 for easy splicing. Among them, the longitudinal steel bars 1 are the main stress-bearing steel bars, which can be prestressed steel bars or ordinary steel bars, and the transverse steel bars 2 are distribution steel bars, which can be ordinary steel bars. The longitudinal steel bars 1 and the transverse steel bars 2 are perpendicular to each other on the horizontal plane, and the longitudinal steel bars 1 are located above the transverse steel bars 2 and are tied together to form an integral body. Longitudinal truss bars 3 and transverse truss bars 4 are arranged vertically upward in two directions (if it is a one-way slab composite slab (Embodiment 2), only longitudinal truss bars 3 need to be arranged). Both the longitudinal truss bars 3 and the transverse truss bars 4 include multiple groups of truss bars. A single group of truss bars includes an upper chord steel bar 7, a lower chord steel bar 8, and web bar steel bars 9. Among them, the upper chord steel bar 7 protrudes above the ECC bottom slab 6, and the lower chord steel bar 8 serves as the stress-bearing steel bar under the ECC bottom slab 6, which can play a role in saving steel; the upper chord steel bar 7 can be used as a lifting point, so the ECC bottom slab 6 can be not provided with lifting points; two web bar steel bars 9 are welded to the left and right sides of the upper chord steel bar 7, and two lower chord steel bars 8 are respectively welded to the outer sides of the two web bar steel bars 9 to form a triangular cross-section of the truss bar.

[0038] Step 2: Pouring of the ECC base plate 6. First, pour the cementitious materials (cement, fly ash) and sand into a 30L mixing pan and mix at low speed for 2 minutes in dry condition; pre-stir the weighed water reducing agent and water evenly, and then slowly add them along the mixing pan (finish adding within 1 minute); finally, slowly add the PVA fibers (finish adding within 1 minute). After all the fibers are added, stir at low speed for 2 minutes first, and then at high speed for 3 minutes. If it is observed that the slurry is fully opened and there is no agglomeration phenomenon, it indicates successful mixing, and the mixing process should be completed within 10 minutes. Apply the release agent to the prepared formwork in advance, pour the slurry into the formwork until it covers the lower chord steel bars 8 and part of the web steel bars 9, and then vibrate it on the vibrating table for 60 seconds, scrape and roughen the concrete surface. Demold the specimen after natural curing for 24 hours, and then place it in a standard curing room at a temperature of (20±2)°C and a relative humidity of 95% for 28 days. Thus, the ECC base plate 6 is formed by pouring.

[0039] Step 3: Transportation and installation of the ECC base plate 6. After the precast members of the ECC base plate 6 are fabricated, transport them to the construction site. After setting up the necessary supports, lay the ECC base plate 6, and fix and connect them by inserting steel bars into the adjacent hooks 5 to ensure tight connection between each ECC base plate 6. Set up temporary formwork around the composite slab to ensure no leakage during concrete pouring.

[0040] Step 4: Pouring of the post-cast coal gangue concrete 10. After the precast ECC base plate 6 is installed, pour the concrete made with coal gangue as coarse aggregate above the ECC base plate 6. After forming, demold it after curing for 1 day under the conditions of (20±2)°C and a relative humidity of (95±1)%, and cure the slab in a standard curing room at a temperature of (20±2)°C and a humidity not less than 95% until the test age (in actual projects, the sprinkler curing method is adopted). Thus, the production of the ECC-coal gangue concrete truss composite slab is completed.

[0041] The ECC base plate 6 in this embodiment adopts ECC material, and its components are ordinary Portland cement, Class I fly ash, quartz stone, water, water reducer, and PVA fiber. The water-cement ratio of the ECC material is 0.33, the sand-cement ratio is 0.78, the water reducer dosage is 1%, and the PVA fiber dosage is 2%. It should be noted that the dosage of PVA fiber is a volume ratio, and the dosage of other raw materials is a mass ratio. The above mix ratio design can be adjusted according to specific engineering requirements to obtain the best performance and construction effect. The components of the post-cast coal gangue concrete 10 on the ECC base plate are water, ordinary Portland cement, non-natural coal gangue, ordinary crushed stone, natural sand and admixtures. In order to ensure the strength and mechanical properties of the material, this embodiment uses continuous graded coal gangue with a particle size of 4.75-19 mm as coarse aggregate to replace 30% of ordinary crushed stone. The mass mix ratio of each component is designed to be 1:1.87:1.7:3.96:4.62:0.0076.

[0042] The manufacturing method provided in this embodiment has the following advantages:

[0043] 1. Lightweight advantage: This embodiment uses ECC material as the base plate, coal gangue aggregate concrete as the post-cast concrete, and fly ash as an admixture, which can greatly reduce the weight of the composite board and achieve lightweight. The low density characteristics of ECC material (1600-2000kg / m 3 ), the density of coal gangue aggregate is lower than that of natural crushed stone (apparent density 2440kg / m 3 , bulk density 1080kg / m 3 ), and the low density characteristics of fly ash (1070-2400kg / m 3 ), which together significantly reduced the deadweight of the composite slab, improved construction efficiency and structural performance, and promoted resource recycling and environmental protection.

[0044] 2. Save resources and protect the environment: This embodiment proposes an innovative solution to the problem of large amounts of coal gangue accumulation generated during coal mining. As a by-product of coal mining, coal gangue is traditionally regarded as waste. It has not only failed to be effectively utilized, but also caused serious pollution to the environment. The present invention creatively uses coal gangue as coarse aggregate for post-cast concrete, which not only effectively saves the use of natural coarse aggregates such as gravel and realizes the recycling of resources, but also significantly reduces environmental pollution, which is in line with the concept of sustainable development.

[0045] 3. Convenient construction: Compared with the prefabricated composite panels currently on the market, this embodiment, with its extremely lightweight design advantage, significantly reduces or even eliminates the need for scaffolding during the installation and overlap process, improves construction efficiency, reduces costs, and at the same time ensures the stability and safety of the composite panel installation.

[0046] 4. Good seismic performance: The ECC-coal gangue aggregate concrete composite slab exhibits excellent seismic performance, which is mainly due to the high toughness and bridging effect of the ECC material. The ECC material has extremely high toughness. When an earthquake occurs, although the structure or component will undergo large deformations, due to its ductile failure characteristics, it will not collapse or be damaged immediately, thus providing obvious omens and sufficient escape time for people. In addition, the PVA fibers in the ECC material will produce a bridging effect when subjected to tension, and there will be slow and continuous small slips between the PVA fibers and the cement paste. This process effectively consumes the energy released by the earthquake action and further improves the seismic performance of the structure.

[0047] Example 2

[0048] This example provides a one-way slab composite slab. Then, in step one of Example 1, when laying out, only the longitudinal truss bars 3 need to be laid out, and the transverse truss bars 4 do not need to be laid out, and the remaining manufacturing processes are the same.

[0049] The one-way slab composite slab is suitable for components with large lateral forces, such as beam columns, floors, etc. of floors and roofs. Its width-to-length ratio is generally less than 1 / 3; the two-way slab composite slab is suitable for components that bear complex forces, such as large-span beam columns, cantilevers, and overhanging structures, etc. Its width-to-length ratio is generally greater than 1 / 2.

[0050] The above examples are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above examples. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, improvements and refinements made without departing from the principle of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A manufacturing method of an ECC-coal gangue concrete truss bar composite slab, characterized in that: It includes the following steps: S1. Fabrication of the steel bar grid: According to the specific dimensions of the composite slab, lay a number of orthogonal longitudinal steel bars and transverse steel bars on the formwork. Hooks are provided at the ends of the longitudinal steel bars and transverse steel bars. Arrange longitudinal truss bars and transverse truss bars that are orthogonally arranged longitudinally and transversely and vertically upward, or only arrange longitudinal truss bars. The longitudinal and transverse truss bars both include multiple groups of truss bars; S2. Pouring of the ECC bottom slab: First, pour the cementitious material and sand into the mixing pot and mix at low speed and dry for at least 2 minutes. The cementitious material includes cement and fly ash. Pre-mix the weighed water reducing agent and water evenly in advance, and then slowly add them along the mixing pot and finish adding them within 1 minute. Finally, slowly add PVA fibers and finish adding them within 1 minute. After all the PVA fibers are added, first mix at low speed for 2 minutes, then mix at high speed for 3 minutes until all the slurry is opened and there is no agglomeration phenomenon. The mixing process is completed within 10 minutes; Pre-coat the prepared formwork with a release agent in advance. Pour the slurry into the formwork until it covers some of the truss bars, and then vibrate it on the vibrating table for at least 60 seconds. Level and roughen the concrete surface. Demold after natural curing for at least 24 hours, and then place it in a standard curing room at a temperature of 20±2°C and a relative humidity of 95% for curing for at least 28 days to pour the ECC bottom slab; S3. Installation of the ECC bottom slab: After the ECC bottom slab precast component is fabricated, at the construction site, set up necessary supports, lay the ECC bottom slab, and fix and connect it by inserting steel bars into adjacent hooks. Set up temporary formwork around the composite slab; S4. Pouring of the post-cast coal gangue concrete: After the precast ECC bottom slab is installed, pour concrete made with coal gangue as the coarse aggregate above the ECC bottom slab. After forming, demold after curing for at least 1 day under the conditions of 20±2°C and a relative humidity of 95±1%. Cure the slab in a standard curing room at a temperature of 20±2°C and a humidity of not less than 95% until the test age, or cure it by the method of sprinkling water until the test age, and the production is completed.

2. The manufacturing method of the ECC-coal gangue concrete truss bar composite slab according to claim 1, characterized in that: A single group of truss bars in step S1 includes an upper chord steel bar, a lower chord steel bar, and web bar steel bars distributed in a V shape. Two web bar steel bars are fixed on the left and right sides of the upper chord steel bar, and two lower chord steel bars are respectively welded on the outer sides of the two web bar steel bars to form a triangular cross-section of the truss bar.

3. The manufacturing method of the ECC-coal gangue concrete truss bar composite slab according to claim 1, wherein: The composition of the materials for making the post-cast coal gangue concrete is water, ordinary Portland cement, non-natural coal gangue, ordinary crushed stones, natural sand, and an admixture. The mass ratio of each component is 1:1.87:1.7:3.96:4.62:0.0076.

4. The manufacturing method of the ECC-coal gangue concrete truss bar composite slab according to claim 3, wherein: The non-natural coal gangue is continuously graded coal gangue with a particle size of 4.75 - 19 mm.

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