A synchronous casting function gradient type concrete and a construction method thereof

Abstract

The application discloses a kind of synchronous pouring function gradient type concrete and its construction method, including inner layer structure concrete layer, intermediate layer interface bonding layer and outer layer function concrete layer, the interface bonding layer uses the free-forming mould separator of surface pre-coated interface reinforcing agent;The free-forming mould separator is by two kinds of diamond-shaped mesh staggered distribution scalable mesh component, the interface reinforcing agent is uniformly mixed by P.O.42.5 cement, red mud, modified mortar, water reducing agent, and the mass ratio of each component is 100:(10-20):(50-60):(1-2).Structure concrete layer and function concrete layer are separated by free-forming mould separator, realize the sequential synchronous pouring of function gradient concrete, the unique pore structure of free-forming mould separator allows the "occlusion" of two side concrete parts, while interface reinforcing agent further improves the compatibility and durability of two concrete bonding interface.Compared with traditional function gradient concrete, the application can save construction period, and also can make function gradient concrete different layers realize good combination in "molecular level", realize structure function integration.

Description

Technical Field

[0001] This invention relates to the field of building materials technology for water conservancy and waterway engineering, specifically to a method for synchronously pouring functional gradient concrete and its construction. Background Technology

[0002] In water conservancy and waterway projects, concrete in areas such as spillway sections, water conveyance corridors, and parts subject to collisions with ships faces severe threats of wear and tear, making it highly susceptible to damage such as impact damage, cracking and spalling, exposed and corroded reinforcing steel, and even structural collapse. Once cracks form, external corrosive substances will further penetrate the concrete, exacerbating steel corrosion and concrete decay, creating a vicious cycle.

[0003] Compared to ordinary structural concrete, impact-resistant and wear-resistant concrete is generally more expensive. If the entire structure uses impact-resistant and wear-resistant concrete, the economic cost is high. Actual research revealed that wear primarily occurs on the surface of the structural concrete. Therefore, based on the design principles of functionally graded materials, an impact-resistant and wear-resistant functional layer is added to the surface of the original structural concrete. This functional layer improves the overall protective performance of the concrete, achieving structural-functional integration and improving structural durability. Patent CN113501686B proposes a radiation-resistant functionally graded concrete slab and its preparation method, including a deceleration functional layer and an absorption functional layer sequentially connected from the near-radiation surface. The surface of the deceleration functional layer concrete is embossed, and after hardening, the absorption functional layer is poured. However, the interface between the deceleration and absorption functional layers is a weak point in the functionally graded concrete slab, prone to insufficient durability. Patent CN202110935422.8 proposes covering the surface of alkali-activated slag concrete with a layer of silicate cement mortar or silicate cement concrete, utilizing the excellent anti-carbonation properties of silicate cement to improve the overall durability of the structure. However, the physical properties (such as shrinkage deformation) of alkali-activated slag materials and silicate cement materials differ significantly, and the interface between materials with different properties is a weak point, which is prone to interfacial damage and failure. Therefore, improving the compatibility and bonding quality between concretes with different properties is a key issue in realizing functional gradient structures.

[0004] Furthermore, traditional multi-layer composite structures require roughening the surface after the previous layer has hardened before pouring the next layer, which is time-consuming and labor-intensive. Due to the "sidewall effect," the interface between new and old concrete is a weak area. Because the old concrete has already hydrated, it is difficult for it to hydrate and fuse with the new concrete. Generally speaking, the longer the age interval between the new and old concrete, the worse the bonding performance. Patent CN117822590A provides a method for simultaneous pouring of concrete of different grades, using a steel partition as a separator to pour two different grades of concrete on both sides. The steel partition is removed after the concrete is poured into the formwork but before initial setting. This method achieves simultaneous pouring of different concretes, but it does not solve the bonding problem between concretes with different properties.

[0005] Therefore, in order to improve the durability of concrete in easily worn and damaged parts of water conservancy and waterway projects, and to ensure the quality of interface bonding while improving construction efficiency, it is urgent to develop a highly economical functional gradient concrete and construction method. Summary of the Invention

[0006] To address the shortcomings of existing engineering protective materials, this invention provides a method for synchronously pouring functional gradient concrete and its synchronous pouring construction.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0008] A synchronously cast functional gradient concrete includes an inner structural concrete layer, an intermediate interface bonding layer, and an outer functional concrete layer; the interface bonding layer adopts a formwork-free separator with a pre-coated interface strengthening agent; the formwork-free separator is composed of two types of rhomboid mesh holes that are staggered and have a thickness of 1~2mm.

[0009] In the two types of diamond-shaped meshes of the formwork-free separator, the side length of the first type of diamond-shaped mesh is 0.4 to 0.6 times the maximum aggregate size in structural concrete and functional concrete, and the side length of the second type of diamond-shaped mesh is 0.5 times the side length of the first type of diamond-shaped mesh unit.

[0010] The interface strengthening agent is made by uniformly mixing PO 42.5 cement, red mud, modified mortar, and water-reducing agent, and the mass ratio of each component is 100:(10~20):(50~60):(1~2).

[0011] The red mud is Bayer red mud, with a soluble Na2O content of ≤2.5%.

[0012] The water-reducing agent is a polycarboxylate-based water-reducing agent with a water reduction rate greater than 25%.

[0013] The modified mortar is composed of 20-30 parts of ultrafine fly ash, 40-50 parts of polymer emulsion, 1-2 parts of film-forming aid, 0.2-0.5 parts of PVA fiber, 0.5-2 parts of defoamer, and 100 parts of water.

[0014] The ultrafine fly ash has a particle size of 800 mesh or larger.

[0015] The polymer emulsion is one of an aqueous epoxy emulsion and an aqueous polyurethane emulsion, with a solid content of 40%.

[0016] The film-forming aid is a mixture of dipropylene glycol butyl ether and acetylglucosyl tributyl ester in a ratio of (5~7):(5~3). More preferably, the film-forming aid is a mixture of dipropylene glycol butyl ether and acetylglucosyl tributyl ester in a ratio of 6:4.

[0017] The length of the PVA fiber is 6-18mm, and more preferably, the PVA fiber is a mixture of three lengths of 18mm, 12mm and 6mm in a mass ratio of 1:1:1.

[0018] The defoamer is either a polyether defoamer or a silicone oil defoamer.

[0019] The modified mortar is prepared according to the following method:

[0020] Step 1: Add 20-30 parts of ultrafine fly ash, 40-50 parts of polymer emulsion, 1-2 parts of film-forming aid and 100 parts of water to a mixer in sequence, and stir at 350-550 r / min for 10 min.

[0021] Step 2: Add 0.2~0.5 parts of PVA fiber and stir at 300~400 r / min for 10 min;

[0022] Step 3: Add 0.5 to 2 parts of defoamer and stir at 200 to 300 rpm for 5 minutes to obtain the product.

[0023] The functional concrete layer includes, but is not limited to, impact-resistant and wear-resistant concrete, waterproof concrete, acid-resistant concrete, alkali-resistant concrete, heat-resistant concrete, and radiation-resistant concrete.

[0024] For example, in one embodiment of the present invention, the functional concrete layer is impact-resistant and wear-resistant functional concrete.

[0025] By weight, structural concrete contains the following raw materials: 200-300 parts cement, 50-80 parts fly ash, 500-900 parts river sand, 900-1500 parts crushed stone, 120-150 parts water, and 3-4 parts water-reducing agent.

[0026] By weight, impact-resistant and abrasion-resistant functional concrete contains the following raw materials: 300-350 parts cement, 50-100 parts fly ash, 700-900 parts river sand, 20-40 parts impact-resistant additives, 900-1200 parts crushed stone, 150-170 parts water, and 3-4 parts water-reducing agent.

[0027] The cement is PO 42.5 cement, the river sand is medium sand, the crushed stone particle size does not exceed 80mm, the impact and abrasion resistance additive is a powder composed of nano-SiO2, nano-SiC, expansion agent, fly ash cenospheres and other components, with a moisture content of less than 1.5%, and the water-reducing agent is a polycarboxylate-based water-reducing agent.

[0028] The slump of structural concrete is 50-70 mm, and the slump of functional concrete is 140-160 mm. The difference between the 28-day autogenous volume shrinkage deformation value of the impact-resistant and abrasion-resistant functional concrete layer and that of the structural concrete is less than 10% of the 28-day autogenous volume shrinkage deformation value of the structural concrete.

[0029] The thickness ratio of the functional concrete layer to the structural concrete layer is (1~5):10.

[0030] The functional concrete layer and the structural concrete layer form a "toothed joint" structure at the interface.

[0031] The above-mentioned synchronous pouring construction method for functionally graded concrete includes the following steps:

[0032] Step 1: Based on the overall thickness of the structure and the ratio of the thickness of the structural concrete layer to the functional concrete layer, vertically fix several pieces of formwork-free dividers on the dividing surface. The diamond mesh in the formwork-free dividers is stretched into a square, and the horizontal ends are fixed to the positioning steel bars with steel wire clips.

[0033] Step 2: Prepare the interface strengthening agent. Apply the interface strengthening agent evenly to the surface of the mold-free separator, with a thickness of 1~2mm.

[0034] Step 3: Prepare structural concrete. First, pour the structural concrete into the structural concrete layer, with a pouring height of 30-50cm. Then, prepare the functional concrete and pour it into the functional concrete layer, with a pouring height 5-10cm higher than the structural concrete.

[0035] Step 4: Vibrate the structural concrete and functional concrete in sequence to make the concrete height on both sides of the formwork-free separator the same.

[0036] Step 5: Repeat steps 3 and 4 until the pouring reaches the designed height.

[0037] The wire clip mentioned in step one is a U-shaped galvanized steel wire rope clip, and the vertical positioning steel bar is an HRB400 threaded steel bar with a diameter of 8~10mm and a distance of 5~10cm from the side steel template.

[0038] In step three, the slump of the structural concrete is 50-70mm, and the slump of the functional concrete is 140-160mm.

[0039] In step three, both structural concrete and functional concrete are poured using a hopper method, with a pouring height not exceeding 0.5m.

[0040] In step four, a vibrator is used for compaction. When the compaction area is close to the non-removable formwork divider, the vibrator should be 30-100mm away from the non-removable formwork divider.

[0041] In this invention, the mold-free separator is a 304 stainless steel stretchable mesh component with alternating diamond-shaped mesh openings of two side lengths: 32~48mm and 16~24mm.

[0042] The formwork-free separator consists of a mesh structure with two different sizes of diamond-shaped mesh holes arranged alternately. It is expandable and easy to transport and install. The side length of the first type of diamond-shaped mesh hole is 0.4 to 0.6 times the maximum aggregate size in structural concrete and impact-resistant functional concrete. The side length of the second type of diamond-shaped mesh hole is 0.5 times the side length of the first type of mesh hole unit. This design takes into account the penetration and "interlocking" of the paste and aggregates of different sizes in the concrete, while preventing large aggregates from mixing. Compared with conventional separators with a single shape and aperture, it has better adaptability, especially when the aggregates of the two types of concrete have different particle size distributions, effectively improving the uniformity and bonding quality at the interface. It does not require demolding later, simplifying the construction process. Furthermore, the mesh structure of the formwork-free separator can strengthen the concrete bonding interface.

[0043] A concrete interface hardener is made by uniformly mixing PO 42.5 cement, red mud, modified mortar, and water-reducing agent, with the mass ratio of each component being 100:(10~20):(50~60):(1~2).

[0044] The modified mortar is composed of 20-30 parts of ultrafine fly ash, 40-50 parts of polymer emulsion, 1-2 parts of film-forming aid, 0.2-0.5 parts of PVA fiber, 0.5-2 parts of defoamer, and 100 parts of water.

[0045] The interface strengthening agent, through the rational design of a cement-modified mortar-red mud ternary cementitious system, utilizes the alkali in red mud to activate the activity of the mortar, expanding the application range of high-alkali-content red mud. Mortar is prepared by modifying ultrafine fly ash with polymer emulsion, improving the suspension stability of the mortar. Dipropylene glycol butyl ether (DPnB) combined with tributyl acetyl citrate (ATBC) exhibits a co-solvent effect, enhancing the strength, toughness, and durability of the polymer film. Hybrid fibers are pre-dispersed in the mortar, improving the convenience of subsequent operations; simultaneously, the interwoven fibers form a spatial skeleton, further improving the suspension stability of mortar particles. During preparation, the polymer emulsion and film-forming aid are first mixed, and then a defoamer is added, avoiding interference from the defoamer on the plasticizing effect of the film-forming aid and emulsion particles.

[0046] The slump of structural concrete is 50~70mm, and the slump of impact-resistant and wear-resistant functional concrete is 140~160mm.

[0047] By designing a smaller slump for the structural concrete and a larger slump for the impact-resistant and abrasion-resistant functional concrete layer, and pouring the structural concrete first followed by the impact-resistant and abrasion-resistant functional concrete during simultaneous pouring, the impact of concrete pouring on the formwork-free separator is reduced, preventing deformation of the separator. Furthermore, the incoordination of deformation between concretes with different properties is a significant factor contributing to the weak bond between them; therefore, the technical characteristics of the 28-day autogenous volume shrinkage deformation values ​​of the structural concrete and the impact-resistant and abrasion-resistant functional concrete were defined.

[0048] Beneficial effects:

[0049] This invention provides a method for synchronously pouring functional gradient concrete and its construction, and for the first time clarifies the technical characteristics of the 28-day autogenous volume shrinkage deformation value of structural concrete and functional concrete; the difference between the 28-day autogenous volume shrinkage deformation value of the functional concrete layer and that of the structural concrete is less than 10% of the 28-day autogenous volume shrinkage deformation value of the structural concrete.

[0050] The formwork-free separator designed using this invention allows for the penetration and "interlocking" of the concrete slurry and aggregates of different particle sizes, preventing large aggregates from mixing and effectively improving the uniformity and bonding quality at the interface. It eliminates the need for later formwork removal, simplifying the construction process. Furthermore, the mesh structure of the formwork-free separator strengthens the concrete interface.

[0051] A specialized interface strengthening agent is pre-coated onto the surface of the formwork-free separator. This prevents corrosion and rust on the steel wire surface during construction and enhances the interfacial bonding between the steel wire and the concrete, as well as between the concrete on both sides. Bayer red mud is difficult to utilize due to its high pH and alkali content. This invention, through the rational design of a cement-modified mortar-red mud ternary cementitious system, utilizes the alkali in the red mud to activate the mortar, expanding the application range of high-alkali red mud. The mortar is prepared by modifying ultrafine fly ash with polymer emulsion, improving its suspension stability. Dipropylene glycol butyl ether (DPnB) combined with tributyl acetyl citrate (ATBC) has a co-solvent effect, which can improve the strength, toughness, and durability of the polymer film. Hybrid fibers are pre-dispersed in the mortar, improving the convenience of later operations. Simultaneously, the interwoven fibers form a spatial skeleton, further enhancing the suspension stability of the mortar particles. In the preparation process, the polymer emulsion and film-forming aid are first mixed, and then the defoamer is added to avoid interference with the plasticizing effect of the film-forming aid-emulsion particles.

[0052] This invention also proposes a method for vertically pouring functionally graded concrete composite structures in a synchronous pouring process. During synchronous pouring, the slump of the impact-resistant and wear-resistant functional concrete is greater than that of the structural concrete, and the pouring height of each layer is 5-10 cm higher than that of the structural concrete. Then, vibration is used to make the height the same. Through forced vibration, some of the impact-resistant and wear-resistant functional concrete enters the structural concrete side through the formwork-free separator, forming a "toothed joint" structure on the vertical bonding surface. The two types of concrete are integrated from the plastic stage of pouring, with synchronous hydration and synchronous strength development, achieving a good bond between the two types of concrete at the "molecular level". This avoids the need for later roughening processes and improves construction efficiency and quality.

[0053] In synchronous pouring construction methods, controlling the pouring method using the hopper and reducing the pouring height can minimize disturbance to the formwork-free separator during concrete pouring. Furthermore, maintaining a certain distance between the vibrator and the formwork-free separator ensures that the separator will not deform or misalign during concrete vibration, thereby improving the accuracy and quality of concrete pouring. Attached Figure Description

[0054] Figure 1 This is a schematic cross-sectional view of the synchronously cast functional gradient concrete composite structure of the present invention.

[0055] Figure 2 This is a schematic diagram of the vertical arrangement of the mold-free separator of the present invention.

[0056] Figure 3 This is a schematic diagram of the synchronous pouring construction method of the present invention. During synchronous pouring construction, structural concrete and impact-resistant and wear-resistant functional concrete are poured in sequence according to ①-②-③-④-⑤-⑥-⑦.

[0057] Figure label:

[0058] 1-Inner steel formwork, 2-Structural concrete layer, 3-No-removal formwork divider, 4-Impact and wear-resistant functional concrete layer, 5-Outer steel formwork, 6-Interface strengthening agent, 7-Positioning reinforcement, 8-Side steel formwork, 9-Wire clips. Detailed Implementation

[0059] like Figures 1-2 As shown, the present invention provides a synchronously cast functional gradient concrete, comprising an inner structural concrete layer (2), an intermediate interface bonding layer, and an outer impact-resistant and wear-resistant functional concrete layer (4). The interface bonding layer adopts a formwork-free separator (3) with a surface pre-coated interface strengthening agent (6). The functional gradient concrete is cast between the inner steel formwork (1) and the outer steel formwork (5).

[0060] The formwork-free separator (3) uses wire clips (9) to vertically fix several formwork-free separators (3) between the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4). The horizontal ends of the formwork-free separator (3) are fixed to the positioning reinforcement (7) with wire clips (9).

[0061] Among them, the impact-resistant and wear-resistant functional concrete layer (4) mainly bears the impact and friction of sandy water flow and passing ships, but its thickness is small, and the thickness ratio with the structural concrete layer is (1~5):10.

[0062] The formwork-free divider is a stretchable mesh component consisting of two types of diamond-shaped meshes interspersed. The side length of the first type of diamond mesh is 0.4 to 0.6 times the maximum aggregate size in the structural concrete and the impact-resistant and wear-resistant functional concrete. The side length of the second type of diamond mesh is 0.5 times the side length of the first type of diamond mesh unit. Based on the actual concrete design dimensions (length and height), the required number of formwork-free dividers is calculated. Then, steel wire clips (9) are used to vertically fix the formwork-free dividers (3) between the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4), and the horizontal ends are fixed to the positioning steel bars (7). The steel wire clips (9) are U-shaped galvanized steel wire rope clips, and the vertical positioning steel bars (7) are HRB400 threaded steel bars with a diameter of 8 to 10 mm, and are 5 to 10 cm away from the side steel formwork (8).

[0063] To optimize this solution, during implementation, the surface of the formwork-free separator (3) is uniformly coated with interface strengthening agent (6) to a thickness of 1-2 mm. This prevents corrosion and rust on the surface of the welded wire mesh during construction and enhances the interfacial bonding performance between the wire mesh and the concrete.

[0064] like Figure 3 As shown, the construction method for synchronously casting functionally graded concrete composite structures according to the present invention is carried out according to the following steps:

[0065] Step 1: Based on the overall thickness of the structure and the ratio of the thickness of the structural concrete layer (2) to the impact-resistant and wear-resistant functional concrete layer (4), several pieces of formwork-free dividers (3) are vertically fixed on the dividing surface. The diamond mesh in the formwork-free divider is stretched into a square, and the horizontal ends are fixed to the positioning steel bars (7) with steel wire clips (9).

[0066] Step 2: Prepare interface strengthening agent (6) and evenly coat the surface of the mold-free separator (3) with interface strengthening agent (6);

[0067] Step 3: Prepare the structural concrete layer (2). First, pour the structural concrete into the structural concrete layer at a height of 30-50cm. Then, prepare the impact-resistant and wear-resistant functional concrete layer (4). Pour the impact-resistant and wear-resistant functional concrete into the impact-resistant and wear-resistant functional concrete layer at a height of 5-10cm higher than the structural concrete layer (2).

[0068] Step 4: Vibrate the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4) in sequence to make the concrete height on both sides of the formwork-free separator (3) the same;

[0069] Step 5: Repeat steps 3 and 4, that is, pour structural concrete and impact-resistant and wear-resistant functional concrete in the order of ①-②-③-④-⑤-⑥-⑦ until the design height is reached.

[0070] The present invention will now be described in detail with reference to specific embodiments.

[0071] The mix proportions of the structural concrete and the impact-resistant and abrasion-resistant functional concrete are shown in Table 1. The cement used is PO42.5 cement, the fly ash is Grade II fly ash, the river sand has a fineness modulus of 2.6 and a mud content of 0.5%, and 5~20 mm, 20~40 mm, and 40~80 mm crushed stone is used. Tap water is used for mixing, and polycarboxylate superplasticizer is used at a dosage of 1.0%. The impact-resistant additive is HLC-SF522 impact-resistant and abrasion-resistant agent produced by Nanjing Ruide High-Tech Co., Ltd. The 28-day autogenous volume shrinkage deformation rate ratio of the impact-resistant and abrasion-resistant functional concrete and the structural concrete is 102%. The 28-day splitting tensile strengths of the impact-resistant and abrasion-resistant functional concrete and the structural concrete are 3.8 MPa and 3.5 MPa, respectively. Referring to "5.4 Concrete Bond Strength Test" in SL / T 352-2020, the structural concrete was used as the bonding reference block, and then the impact-resistant and abrasion-resistant functional concrete was poured in. The 28-day bond strength was tested and found to be 1.6 MPa.

[0072] Table 1 Concrete mix proportions (kg / m³) 3 )

[0073] Structural concrete 257 63 547 0 422 422 563 135 3.2 Impact-resistant and wear-resistant concrete 312 78 761 30 315 736 0 160 3.9

[0074] Example 1

[0075] A synchronously cast functional gradient concrete includes an inner structural concrete layer, an intermediate interface bonding layer, and an outer impact-resistant and wear-resistant functional concrete layer. The intermediate interface bonding layer uses a formwork-free separator with a pre-coated interface strengthening agent. The slump of the structural concrete layer (2) is 50 mm, and the slump of the impact-resistant and wear-resistant functional concrete layer (4) is 140 mm, with a thickness ratio of 1:10 to that of the structural concrete layer (2). The formwork-free separator (3) is a 304 stainless steel stretchable mesh component with alternating diamond mesh openings of 32 mm and 16 mm side lengths, and a thickness of 1 mm. The interface strengthening agent (6) is made by mixing PO42.5 cement, red mud, modified mortar and water-reducing agent in a mass ratio of 100:10:50:1. The red mud has a soluble Na2O content of 1.0%. The modified mortar consists of 20 parts of ultrafine fly ash, 40 parts of water-based epoxy emulsion, 1 part of film-forming aid (dipropylene glycol butyl ether and acetylsicit tributyl ester mixed in a 6:4 ratio) and 100 parts of water in sequence into a mixer and stirred at 350 r / min for 10 min. 0.2 parts of PVA fiber (PVA fiber is a mixture of three lengths of 18 mm, 12 mm and 6 mm in a mass ratio of 1:1:1) are added and stirred at 300 r / min for 10 min. Then 0.5 parts of polyether defoamer are added and stirred at 200 r / min for 5 min. The wire clip (9) is a U-shaped galvanized steel wire rope clip, and the vertical positioning steel bar (7) is an HRB400 threaded steel bar with a diameter of 8mm and a distance of 5cm from the side steel template (8).

[0076] Follow these steps to pour functional gradient concrete simultaneously:

[0077] Step 1: Lay out the structure according to the thickness ratio (1:10) of the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4), and fix several pieces of formwork-free dividers (3) vertically on the dividing surface. The diamond mesh in the formwork-free divider is stretched into a square, and the horizontal ends are fixed to the positioning steel bars (7) with steel wire clips (9).

[0078] Step 2: Prepare the interface strengthening agent (6) and evenly coat the surface of the mold-free separator (3) with a thickness of 1mm;

[0079] Step 3: Prepare the structural concrete layer (2). First, pour the structural concrete into the structural concrete layer slab using a hopper, with a pouring height of 0.3m. The pouring height of the structural concrete layer (2) is 30cm. Next, prepare the impact-resistant and wear-resistant functional concrete layer (4). Pour the impact-resistant and wear-resistant functional concrete into the impact-resistant and wear-resistant functional concrete layer slab using the same hopper method. The pouring height is 5cm higher than that of the structural concrete layer (2).

[0080] Step 4: Use a ZN50 vibrator to vibrate the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4) in sequence, so that the concrete height on both sides of the formwork-free separator (3) is the same, and the vibrator is 30mm away from the formwork-free separator (3).

[0081] Step 5: Repeat steps 3 and 4 until the pouring reaches the designed height.

[0082] Example 2

[0083] A synchronously cast functional gradient concrete includes an inner structural concrete layer, an intermediate interface bonding layer, and an outer impact-resistant and wear-resistant functional concrete layer. The intermediate interface bonding layer uses a formwork-free separator with a pre-coated interface strengthening agent. The slump of the structural concrete layer (2) is 70 mm, and the slump of the impact-resistant and wear-resistant functional concrete layer (4) is 160 mm, with a thickness ratio of 5:10 between the two layers. The formwork-free separator (3) is a 304 stainless steel stretchable mesh component with alternating diamond mesh openings of 48 mm and 24 mm side lengths and a thickness of 2 mm. The interface strengthening agent (6) is made by mixing PO 42.5 cement, red mud, modified mortar, water-reducing agent and other components in a mass ratio of 100:20:60:2. The red mud has a soluble Na2O content of 2.5%. The modified mortar consists of 30 parts of ultrafine fly ash, 50 parts of waterborne polyurethane emulsion, 2 parts of film-forming aid (dipropylene glycol butyl ether and acetylsicit tributyl ester mixed in a 6:4 ratio) and 100 parts of water in sequence into a mixer and stirred at 550 r / min for 10 min. 0.5 parts of PVA fiber (PVA fiber is a mixture of three lengths of 18 mm, 12 mm and 6 mm in a mass ratio of 1:1:1) are added and stirred at 400 r / min for 10 min. Then 2 parts of silicone oil defoamer are added and stirred at 300 r / min for 5 min to obtain the final product. The wire clip (9) is a U-shaped galvanized steel wire rope clip, and the vertical positioning steel bar (7) is an HRB400 threaded steel bar with a diameter of 10mm and a distance of 10cm from the side steel template (8).

[0084] Follow these steps to pour functional gradient concrete simultaneously:

[0085] Step 1: Lay out the structure according to the thickness ratio (5:10) of the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4), and fix several pieces of formwork-free dividers (3) vertically on the dividing surface. The diamond mesh in the formwork-free divider is stretched into a square, and the horizontal ends are fixed to the positioning steel bar (7) with steel wire clips (9).

[0086] Step 2: Prepare the interface strengthening agent (6) and evenly coat the surface of the mold-free separator (3) with a thickness of 2mm;

[0087] Step 3: Prepare the structural concrete layer (2). First, pour the structural concrete into the structural concrete layer slab using a hopper, with a pouring height of 0.4m and a pouring height of 50cm. Then, prepare the impact-resistant and wear-resistant functional concrete layer (4). Pour the impact-resistant and wear-resistant functional concrete into the impact-resistant and wear-resistant functional concrete layer slab using the same hopper method, with a pouring height 10cm higher than that of the structural concrete layer (2).

[0088] Step 4: Use a ZN50 vibrator to vibrate the structural concrete and the impact-resistant and wear-resistant functional concrete in sequence, so that the concrete height on both sides of the formwork-free separator (3) is the same, and the vibrator is 100mm away from the formwork-free separator (3).

[0089] Step 5: Repeat steps 3 and 4 until the pouring reaches the designed height.

[0090] Example 3

[0091] A synchronously cast functional gradient concrete includes an inner structural concrete layer, an intermediate interface bonding layer, and an outer impact-resistant and wear-resistant functional concrete layer. The intermediate interface bonding layer uses a formwork-free separator with a pre-coated interface strengthening agent. The slump of the structural concrete layer (2) is 60 mm, and the slump of the impact-resistant and wear-resistant functional concrete layer (4) is 145 mm, with a thickness ratio of 2:10 between the two layers. The formwork-free separator (3) is a 304 stainless steel stretchable mesh component with alternating diamond mesh openings of 36 mm and 18 mm side lengths, and a thickness of 1.5 mm. The interface strengthening agent (6) is made by mixing PO 42.5 cement, red mud, modified mortar, water-reducing agent and other components in a mass ratio of 100:20:60:1. The red mud has a soluble Na2O content of 2.0%. The modified mortar is made by adding 25 parts of ultrafine fly ash, 45 parts of water-based epoxy emulsion, 1.5 parts of film-forming aid (dipropylene glycol butyl ether and acetylsicit tributyl ester mixed in a 6:4 ratio) and 100 parts of water into a mixer and stirring at 400 r / min for 10 min. Then, 0.3 parts of PVA fiber are added and stirred at 350 r / min for 10 min. Finally, 1 part of silicone oil defoamer is added and stirred at 250 r / min for 5 min. The wire clip (9) is a U-shaped galvanized steel wire rope clip. The vertical positioning steel bar (7) is an HRB400 threaded steel bar with a diameter of 7 mm and a distance of 7 cm from the side steel template (8).

[0092] Follow these steps to pour functional gradient concrete simultaneously:

[0093] Step 1: Lay out the structure according to the thickness ratio (2:10) of the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4), and fix several pieces of formwork-free dividers (3) vertically on the dividing surface. The diamond mesh in the formwork-free divider is stretched into a square, and the horizontal ends are fixed to the positioning steel bar (7) with steel wire clips (9).

[0094] Step 2: Prepare the interface strengthening agent (6) and evenly coat the surface of the mold-free separator (3) with a thickness of 1.5 mm.

[0095] Step 3: Prepare the structural concrete layer (2). First, pour the structural concrete into the structural concrete layer slab using a hopper, with a drop height of 0.5m and a pouring height of 40cm. Then, prepare the impact-resistant and wear-resistant functional concrete layer (4). Pour the impact-resistant and wear-resistant functional concrete into the impact-resistant and wear-resistant functional concrete layer slab using the same hopper method, with a pouring height 6cm higher than the structural concrete layer (2).

[0096] Step 4: Use a ZN50 vibrator to vibrate the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4) in sequence, so that the concrete height on both sides of the formwork-free separator (3) is the same, and the vibrator is 50mm away from the formwork-free separator (3).

[0097] Step 5: Repeat steps 3 and 4 until the pouring reaches the designed height.

[0098] Example 4

[0099] A synchronously cast functional gradient concrete includes an inner structural concrete layer, an intermediate interface bonding layer, and an outer impact-resistant and wear-resistant functional concrete layer. The intermediate interface bonding layer uses a formwork-free separator with a pre-coated interface strengthening agent. The slump of the structural concrete layer (2) is 55 mm, and the slump of the impact-resistant and wear-resistant functional concrete layer (4) is 150 mm, with a thickness ratio of 3:10 between the two layers. The formwork-free separator (3) is a 304 stainless steel stretchable mesh component with alternating diamond mesh openings of 40 mm and 20 mm side lengths and a thickness of 1 mm. The interface strengthening agent (6) is made by mixing PO 42.5 cement, red mud, modified mortar, water-reducing agent and other components in a mass ratio of 100:10:50:1. The red mud has a soluble Na2O content of 1.5%. The modified mortar consists of 22 parts ultrafine fly ash, 42 parts water-based polyurethane emulsion, 1.2 parts film-forming aid (dipropylene glycol butyl ether and acetylsicit tributyl ester mixed in a 6:4 ratio) and 100 parts water in sequence in a mixer and is stirred at 450 r / min for 10 min. 0.4 parts PVA fiber are added and stirred at 320 r / min for 10 min. Then 1.5 parts silicone oil defoamer are added and stirred at 220 r / min for 5 min. The wire clip (9) is a U-shaped galvanized steel wire rope clip. The vertical positioning steel bar (7) is an HRB400 threaded steel bar with a diameter of 8 mm and a distance of 6 cm from the side steel template (8).

[0100] Follow these steps to pour functional gradient concrete simultaneously:

[0101] Step 1: Lay out the structure according to the thickness ratio (3:10) of the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4). Vertically fix several pieces of formwork-free dividers (3) on the dividing surface. The diamond mesh in the formwork-free dividers is stretched into a square, and the horizontal ends are fixed to the positioning steel bars (7) with steel wire clips (9).

[0102] Step 2: Prepare the interface strengthening agent (6) and evenly coat the surface of the mold-free separator (3) with a thickness of 1.2 mm;

[0103] Step 3: Prepare the structural concrete layer (2). First, pour the structural concrete into the structural concrete layer slab using a hopper, with a drop height of 0.5m and a pouring height of 30cm. Then, prepare the impact-resistant and wear-resistant functional concrete layer (4). Pour the impact-resistant and wear-resistant functional concrete into the impact-resistant and wear-resistant functional concrete layer slab using the same hopper method, with a pouring height 8cm higher than the structural concrete layer (2).

[0104] Step 4: Use a ZN50 vibrator to vibrate the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4) in sequence, so that the concrete height on both sides of the formwork-free separator (3) is the same, and the vibrator is 60mm away from the formwork-free separator (3).

[0105] Step 5: Repeat steps 3 and 4 until the pouring reaches the designed height.

[0106] Example 5

[0107] A synchronously cast functional gradient concrete includes an inner structural concrete layer, an intermediate interface bonding layer, and an outer impact-resistant and wear-resistant functional concrete layer. The intermediate interface bonding layer uses a formwork-free separator with a pre-coated interface strengthening agent. The slump of the structural concrete layer (2) is 65 mm, and the slump of the impact-resistant and wear-resistant functional concrete layer (4) is 155 mm, with a thickness ratio of 4:10 between the two layers. The formwork-free separator (3) is a 304 stainless steel stretchable mesh component with alternating diamond mesh openings of 44 mm and 22 mm side lengths and a thickness of 2 mm. The interface strengthening agent (6) is made by mixing PO 42.5 cement, red mud, modified mortar, water-reducing agent and other components in a mass ratio of 100:15:60:1.5. The red mud has a soluble Na2O content of 1.9%. The modified mortar consists of 27 parts ultrafine fly ash, 45 parts water-based polyurethane emulsion, 1.5 parts film-forming aid (dipropylene glycol butyl ether and acetylsicit tributyl ester mixed in a 6:4 ratio) and 100 parts water in sequence in a mixer and is stirred at 500 r / min for 10 min. 0.2 parts PVA fiber are added and stirred at 340 r / min for 10 min. Then 2 parts polyether defoamer are added and stirred at 270 r / min for 5 min. The wire clip (9) is a U-shaped galvanized steel wire rope clip. The vertical positioning steel bar (7) is an HRB400 threaded steel bar with a diameter of 10 mm and a distance of 8 cm from the side steel template (8).

[0108] Follow these steps to pour functional gradient concrete simultaneously:

[0109] Step 1: Lay out the structure according to the thickness ratio (4:10) of the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4), and fix several pieces of formwork-free dividers (3) vertically on the dividing surface. The diamond mesh in the formwork-free divider is stretched into a square, and the horizontal ends are fixed to the positioning steel bar (7) with steel wire clips (9).

[0110] Step 2: Prepare the interface strengthening agent (6) and evenly coat the surface of the mold-free separator (3) with a thickness of 1.4 mm;

[0111] Step 3: Prepare the structural concrete layer (2). First, pour the structural concrete into the structural concrete layer slab using a hopper, with a drop height of 0.4m and a pouring height of 40cm. Then, prepare the impact-resistant and wear-resistant functional concrete layer (4). Pour the impact-resistant and wear-resistant functional concrete into the impact-resistant and wear-resistant functional concrete layer slab using the same hopper method, with a pouring height 7cm higher than the structural concrete layer (2).

[0112] Step 4: Use a ZN50 vibrator to vibrate the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4) in sequence, so that the concrete height on both sides of the formwork-free separator (3) is the same, and the vibrator is 80mm away from the formwork-free separator (3).

[0113] Step 5: Repeat steps 3 and 4 until the pouring reaches the designed height.

[0114] Example 6

[0115] A synchronously cast functional gradient concrete includes an inner structural concrete layer, an intermediate interface bonding layer, and an outer impact-resistant and wear-resistant functional concrete layer. The intermediate interface bonding layer uses a formwork-free separator with a pre-coated interface strengthening agent. The slump of the structural concrete layer (2) is 50 mm, and the slump of the impact-resistant and wear-resistant functional concrete layer (4) is 150 mm, with a thickness ratio of 1:10 between the two layers. The formwork-free separator (3) is a 304 stainless steel stretchable mesh component with alternating diamond mesh openings of 32 mm and 16 mm side lengths, and a thickness of 1.5 mm. The interface strengthening agent (6) is made by mixing PO 42.5 cement, red mud, modified mortar, water-reducing agent and other components in a mass ratio of 100:12:55:1.5. The red mud contains 0.5% soluble Na2O. The modified mortar consists of 30 parts ultrafine fly ash, 50 parts water-based polyurethane emulsion, 1.8 parts film-forming aid (dipropylene glycol butyl ether and acetylsicit tributyl ester mixed in a 6:4 ratio) and 100 parts water in sequence in a mixer and is stirred at 375 r / min for 10 min. 0.4 parts PVA fiber are added and stirred at 360 r / min for 10 min. Then 1 part polyether defoamer is added and stirred at 280 r / min for 5 min. The wire clip (9) is a U-shaped galvanized steel wire rope clip. The vertical positioning steel bar (7) is an HRB400 threaded steel bar with a diameter of 9 mm and a distance of 5 cm from the side steel template (8).

[0116] Follow these steps to pour functional gradient concrete simultaneously:

[0117] Step 1: Lay out the structure according to the thickness ratio (1:10) of the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4), and fix several pieces of formwork-free dividers (3) vertically on the dividing surface. The diamond mesh in the formwork-free divider is stretched into a square, and the horizontal ends are fixed to the positioning steel bars (7) with steel wire clips (9).

[0118] Step 2: Prepare the interface strengthening agent (6) and evenly coat the surface of the mold-free separator (3) with a thickness of 1.8 mm.

[0119] Step 3: Prepare the structural concrete layer (2). First, pour the structural concrete into the structural concrete layer slab using a hopper, with a drop height of 0.3m and a pouring height of 50cm. Then, prepare the impact-resistant and wear-resistant functional concrete layer (4). Pour the impact-resistant and wear-resistant functional concrete into the impact-resistant and wear-resistant functional concrete layer slab using the same hopper method, with a pouring height 9cm higher than the structural concrete layer (2).

[0120] Step 4: Use a ZN50 vibrator to vibrate the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4) in sequence, so that the concrete height on both sides of the formwork-free separator (3) is the same, and the vibrator is 40mm away from the formwork-free separator (3).

[0121] Step 5: Repeat steps 3 and 4 until the pouring reaches the designed height.

[0122] Example 7

[0123] A synchronously cast functional gradient concrete includes an inner structural concrete layer, an intermediate interface bonding layer, and an outer impact-resistant and wear-resistant functional concrete layer. The intermediate interface bonding layer uses a formwork-free separator with a pre-coated interface strengthening agent. The slump of the structural concrete layer (2) is 60 mm, and the slump of the impact-resistant and wear-resistant functional concrete layer (4) is 140 mm, with a thickness ratio of 2:10 between the two layers. The formwork-free separator (3) is a 304 stainless steel stretchable mesh component with alternating diamond mesh openings of 48 mm and 24 mm side lengths and a thickness of 1.2 mm. The interface strengthening agent (6) is made by mixing PO 42.5 cement, red mud, modified mortar, water-reducing agent and other components in a mass ratio of 100:15:55:1. The red mud has a soluble Na2O content of 2.2%. The modified mortar is made by adding 20 parts of ultrafine fly ash, 45 parts of water-based epoxy emulsion, 1.5 parts of film-forming aid (dipropylene glycol butyl ether and acetylsicit tributyl ester mixed in a 6:4 ratio) and 100 parts of water into a mixer and stirring at 350 r / min for 10 min. Then, 0.3 parts of PVA fiber are added and stirred at 350 r / min for 10 min. Finally, 0.5 parts of polyether defoamer are added and stirred at 250 r / min for 5 min. The wire clip (9) is a U-shaped galvanized steel wire rope clip. The vertical positioning steel bar (7) is an HRB400 threaded steel bar with a diameter of 8 mm and a distance of 8 cm from the side steel template (8).

[0124] Follow these steps to pour functional gradient concrete simultaneously:

[0125] Step 1: Lay out the structure according to the thickness ratio (2:10) of the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4), and fix several pieces of formwork-free dividers (3) vertically on the dividing surface. The diamond mesh in the formwork-free divider is stretched into a square, and the horizontal ends are fixed to the positioning steel bar (7) with steel wire clips (9).

[0126] Step 2: Prepare the interface strengthening agent (6) and evenly coat the surface of the mold-free separator (3) with a thickness of 1mm;

[0127] Step 3: Prepare the structural concrete layer (2). First, pour the structural concrete into the structural concrete layer slab using a hopper, with a drop height of 0.3m and a pouring height of 30cm. Then, prepare the impact-resistant and wear-resistant functional concrete layer (4). Pour the impact-resistant and wear-resistant functional concrete into the impact-resistant and wear-resistant functional concrete layer slab using the same hopper method, with a pouring height 6cm higher than the structural concrete layer (2).

[0128] Step 4: Use a ZN50 vibrator to vibrate the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4) in sequence, so that the concrete height on both sides of the formwork-free separator (3) is the same, and the vibrator is 90mm away from the formwork-free separator (3).

[0129] Step 5: Repeat steps 3 and 4 until the pouring reaches the designed height.

[0130] Example 8

[0131] A synchronously cast functional gradient concrete includes an inner structural concrete layer, an intermediate interface bonding layer, and an outer impact-resistant and wear-resistant functional concrete layer. The intermediate interface bonding layer uses a formwork-free separator with a pre-coated interface strengthening agent. The slump of the structural concrete layer (2) is 70 mm, and the slump of the impact-resistant and wear-resistant functional concrete layer (4) is 160 mm, with a thickness ratio of 5:10 between the two layers. The formwork-free separator (3) is a 304 stainless steel stretchable mesh component with alternating diamond mesh openings of 35 mm and 17.5 mm side lengths and a thickness of 1.8 mm. The interface strengthening agent (6) is made by mixing PO 42.5 cement, red mud, modified mortar, water-reducing agent and other components in a mass ratio of 100:20:50:1.5. The red mud contains 2% soluble Na2O. The modified mortar consists of 30 parts ultrafine fly ash, 50 parts water-based epoxy emulsion, 2 parts film-forming aid (dipropylene glycol butyl ether and acetylsicit tributyl ester mixed in a 6:4 ratio) and 100 parts water in sequence in a mixer and is stirred at 450 r / min for 10 min. 0.5 parts PVA fiber are added and stirred at 400 r / min for 10 min. Then 2 parts silicone oil defoamer are added and stirred at 300 r / min for 5 min. The wire clip (9) is a U-shaped galvanized steel wire rope clip. The vertical positioning steel bar (7) is an HRB400 threaded steel bar with a diameter of 10 mm and a distance of 10 cm from the side steel template (8).

[0132] Follow these steps to pour functional gradient concrete simultaneously:

[0133] Step 1: Lay out the structure according to the thickness ratio (5:10) of the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4), and fix several pieces of formwork-free dividers (3) vertically on the dividing surface. The diamond mesh in the formwork-free divider is stretched into a square, and the horizontal ends are fixed to the positioning steel bar (7) with steel wire clips (9).

[0134] Step 2: Prepare the interface strengthening agent (6) and evenly coat the surface of the mold-free separator (3) with a thickness of 2mm;

[0135] Step 3: Prepare the structural concrete layer (2). First, pour the structural concrete into the structural concrete layer slab using a hopper, with a drop height of 0.4m and a pouring height of 40cm. Then, prepare the impact-resistant and wear-resistant functional concrete layer (4). Pour the impact-resistant and wear-resistant functional concrete into the impact-resistant and wear-resistant functional concrete layer slab using the same hopper method, with a pouring height 10cm higher than the structural concrete layer (2).

[0136] Step 4: Use a ZN50 vibrator to vibrate the structural concrete layer (2) and the impact-resistant and wear-resistant functional concrete layer (4) in sequence, so that the concrete height on both sides of the formwork-free separator (3) is the same, and the vibrator is 80mm away from the formwork-free separator (3).

[0137] Step 5: Repeat steps 3 and 4 until the pouring reaches the designed height.

[0138] Comparative Example 1

[0139] The synchronous pouring of functional gradient concrete and the pouring method in Comparative Example 1 are basically the same as those in Example 4, except that the slump of both structural concrete and impact-resistant and wear-resistant functional concrete is 150mm.

[0140] Comparative Example 2

[0141] Comparative Example 2 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that the side lengths of the two rhomboid meshes of the formwork-free separator (3) are 30mm and 15mm respectively.

[0142] Comparative Example 3

[0143] Comparative Example 3 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that the side length of the two rhomboid meshes of the formwork-free separator (3) is 40mm.

[0144] Comparative Example 4

[0145] Comparative Example 4 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that the surface of the formwork-free separator (3) is not coated with interface strengthening agent (6).

[0146] Comparative Example 5

[0147] Comparative Example 5 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that the interface strengthening agent (6) is made by mixing PO 42.5 cement, red mud, modified mortar, water reducing agent and other components in a mass ratio of 100:30:50:1.

[0148] Comparative Example 6

[0149] Comparative Example 6 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that the content of red mud soluble Na2O in the interface strengthening agent (6) is 3%.

[0150] Comparative Example 7

[0151] Comparative Example 7 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that the film-forming aid is dipropylene glycol butyl ether.

[0152] Comparative Example 8

[0153] Comparative Example 8 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that the film-forming aid is a mixture of dipropylene glycol butyl ether and dimethyl phthalate in a ratio of 6:4.

[0154] Comparative Example 9

[0155] Comparative Example 9 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that PVA fibers are not added in the mortar preparation.

[0156] Comparative Example 10

[0157] Comparative Example 10 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that: the silicone oil defoamer is added together with ultrafine fly ash, waterborne polyurethane emulsion and film-forming aid. That is, the modified mortar is made by adding 22 parts ultrafine fly ash, 42 parts waterborne polyurethane emulsion, 1.2 parts film-forming aid (dipropylene glycol butyl ether and acetylsicit tributyl ester mixed at a ratio of 6:4), 1.5 parts silicone oil defoamer and 100 parts water to a mixer in sequence and stirring at 450 r / min for 10 min; then adding 0.4 parts PVA fiber and stirring at 320 r / min for 10 min.

[0158] Comparative Example 11

[0159] Comparative Example 11 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that the pouring height of the impact-resistant and wear-resistant functional concrete layer (4) in step three is the same as that of the structural concrete layer (2).

[0160] Comparative Example 12

[0161] Comparative Example 12 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that the drop height of the impact-resistant and wear-resistant functional concrete and the structural concrete is 0.6m when they are poured by hopper.

[0162] Comparative Example 13

[0163] Comparative Example 13 is basically the same as the synchronous pouring of functional gradient concrete and the pouring method in Example 4, except that the vibrator is 10mm away from the formwork-free separator (3) in step four.

[0164] Effect verification

[0165] Functionally graded concrete was prepared according to the application examples 1-8 and comparative examples 1-13, and simulation tests were conducted with a total pouring height of 2m. Concrete performance indicators were recorded during pouring. Core samples were taken from the concrete after demolding and water curing for 28 days. Bonded cubic block specimens with the bonding surface in the center and bonded frustum block impermeability specimens with the bonding surface in the center were prepared according to SL / T 352-2020 (the exposed steel wire ends on the water-facing side were sealed). The bond strength and relative permeability coefficient of the concrete specimens containing the bonding surface were tested according to SL / T 352-2020, and the results are shown in Table 2 below.

[0166] The 28-day splitting tensile strengths of impact-resistant and abrasion-resistant functional concrete and structural concrete are 3.8 MPa and 3.5 MPa, respectively. Referring to "5.4 Concrete Bond Strength Test" in SL / T 352-2020, structural concrete was used as the bonding reference block, and then impact-resistant and abrasion-resistant functional concrete was poured in, and its 28-day bond strength was tested to be 1.6 MPa.

[0167] Table 2 Performance test results of each group of concrete composite structures

[0168]

[0169] As shown in Table 2, the functionally graded concrete and its pouring method proposed in this invention have good feasibility. Compared with traditional construction methods, it can save construction time and achieve a good bond between the two types of concrete. During the simultaneous pouring process in Examples 1-8, the formwork-free separator does not deform, and the bonding surface can be vibrated and compacted, ensuring the realization of the simultaneous pouring process. Looking at the performance of the hardened concrete test blocks, the bond strength of each concrete is between 3.5 and 3.9 MPa, significantly higher than the bond strength between new and old concrete in the traditional pouring method (1.6 MPa), and basically equivalent to or even higher than the splitting tensile strength of the impact-resistant and abrasion-resistant functional concrete and structural concrete themselves. This is mainly due to the reinforcing effect of the formwork-free separator. Furthermore, the relative permeability coefficient of the composite concrete structure is also relatively low.

[0170] Compared to Example 4, in Comparative Example 1, both types of concrete had a slump of 150mm. During the pouring process, the structural concrete impacted the formwork separator, causing deformation and affecting the density of the bonding surface. Therefore, the bond strength decreased and the relative permeability coefficient increased. In Comparative Example 2, the two types of rhomboid mesh in the formwork separator had side lengths of 30mm and 15mm, respectively. The mesh diameter was too small, making it difficult for the concrete slurry and aggregate on both sides to penetrate and "interlock," thus affecting the interface bonding. In Comparative Example 3, the two types of rhomboid mesh in the formwork separator (3) had side lengths of 40mm. The impact-resistant and abrasion-resistant concrete could more easily pass through the formwork separator, making it difficult to ensure the uniformity and bonding quality of the interface. In Comparative Example 4, the surface of the formwork separator (3) was not coated with interface strengthening agent (6), which reduced the bonding quality between the wire mesh and the concrete and affected the interface strength. In Comparative Example 5, the red mud content in the interface strengthening agent (6) formula was too high, which reduced the performance of the interface agent and thus affected the interface bonding quality. In Comparative Example 6, the red mud soluble Na2O content in the interface strengthening agent (6) was 3%, which also led to a decrease in the performance of the interface agent. In Comparative Example 7, the film-forming aid was dipropylene glycol butyl ether, which has a high boiling point and slow film-forming speed, resulting in a decrease in the polymer film-forming performance. In Comparative Example 8, the film-forming aid was obtained by mixing dipropylene glycol butyl ether and dimethyl phthalate in a 6:4 ratio. The two compounds do not have a co-solvent effect, which reduces the film-forming performance. In Comparative Example 9, PVA fibers were not added during the preparation of the mortar. On the one hand, the stability of the mortar deteriorated, and it was prone to sedimentation. On the other hand, the lack of fiber bridging effect at the interface reduced the quality of the interface bonding. In Comparative Example 10, the defoamer was added together with the emulsion and the film-forming aid. The defoamer affected the plasticizing effect of the film-forming aid on the emulsion particles, resulting in a decrease in the quality of the film formation. In Comparative Example 11, the two concretes were poured at the same height. The vertical bonding surface could not form a "toothed joint" structure, which affected the quality of the interface pouring. In Comparative Example 12, when the impact-resistant and wear-resistant functional concrete and structural concrete are poured using a hopper method, the pouring height is 0.6m, which easily leads to deformation and misalignment of the formwork-free separator, thus affecting the interface bonding quality. In Comparative Example 13, the vibrator is 30mm away from the formwork-free separator (3). The distance is too close, causing deformation of the formwork-free separator, thus affecting the bonding surface quality.

[0171] Although the present invention has been described through embodiments, these embodiments are not intended to limit the invention. Those skilled in the art can make various modifications and alterations within the spirit of the invention, such as adjustments to component ratios or time ranges. The effects of such adjustments are predictable and therefore also fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined by the same or equivalent technical features in the claims of this application.

Claims

1. A synchronous cast functionally graded concrete, characterized by, It includes an inner structural concrete layer, an intermediate interface bonding layer, and an outer functional concrete layer; the interface bonding layer adopts a formwork-free separator with a pre-coated interface strengthening agent. The formwork-free separator is composed of two types of rhomboid meshes that are interspersed and expandable. The interface strengthening agent is made by mixing PO 42.5 cement, red mud, modified mortar, and water-reducing agent evenly, and the mass ratio of each component is 100:(10~20):(50~60):(1~2). In the two types of diamond-shaped meshes of the formwork-free separator, the side length of the first type of diamond-shaped mesh is 0.4 to 0.6 times the maximum aggregate size in structural concrete and functional concrete, and the side length of the second type of diamond-shaped mesh is 0.5 times the side length of the first type of diamond-shaped mesh unit. The modified mortar is composed of 20-30 parts of ultrafine fly ash, 40-50 parts of polymer emulsion, 1-2 parts of film-forming aid, 0.2-0.5 parts of PVA fiber, 0.5-2 parts of defoamer, and 100 parts of water.

2. The in-situ functionally graded concrete of claim 1, wherein, The polymer emulsion is one of an aqueous epoxy emulsion and an aqueous polyurethane emulsion, and the film-forming aid is a mixture of dipropylene glycol butyl ether and tributyl acetyl citrate in a ratio of (5~7):(5~3).

3. The in-situ functionally graded concrete of claim 1, wherein, The modified mortar is prepared according to the following method: Step 1: Add 20-30 parts of ultrafine fly ash, 40-50 parts of polymer emulsion, 1-2 parts of film-forming aid and 100 parts of water to a mixer in sequence, and stir at 350-550 r / min for 10 min. Step 2: Add 0.2~0.5 parts of PVA fiber and stir at 300~400 r / min for 10 min; Step 3: Add 0.5 to 2 parts of defoamer and stir at 200 to 300 rpm for 5 minutes to obtain the product.

4. The in-situ functionally graded concrete of claim 1, wherein, The thickness ratio of the functional concrete layer to the structural concrete layer is (1~5):

10.

5. A simultaneous casting method of a functionally graded concrete according to any one of claims 1 to 4, wherein Includes the following steps: Step 1: Based on the overall thickness of the structure and the ratio of the thickness of the structural concrete layer to the functional concrete layer, vertically fix several pieces of formwork-free dividers on the dividing surface. The diamond mesh in the formwork-free dividers is stretched into a square, and the horizontal ends are fixed to the positioning steel bars with steel wire clips. Step 2: Prepare the interface strengthening agent. Apply the interface strengthening agent evenly to the surface of the mold-free separator, with a thickness of 1~2mm. Step 3: Prepare structural concrete. First, pour the structural concrete into the structural concrete layer, with a pouring height of 30-50cm. Then, prepare the functional concrete and pour it into the functional concrete layer, with a pouring height 5-10cm higher than the structural concrete. Step 4: Vibrate the structural concrete and functional concrete in sequence to make the concrete height on both sides of the formwork-free separator the same. Step 5: Repeat steps 3 and 4 until the pouring reaches the designed height.

6. The synchronized placement construction method of claim 5, wherein, In step three, the slump of the structural concrete is 50-70mm, and the slump of the functional concrete is 140-160mm.

7. The synchronous pouring construction method according to claim 5, characterized in that, In step three, both structural concrete and functional concrete are poured using a hopper method, with a pouring height not exceeding 0.5m.

8. The synchronized placement construction method of claim 5, wherein, In step four, a vibrator is used for compaction. When the compaction area is close to the non-removable formwork divider, the vibrator should be 30-100mm away from the non-removable formwork divider.

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