Ultra-high performance geopolymer concrete permanent formwork filled with SFCB concrete prefabricated pipe pile and preparation method of ultra-high performance geopolymer concrete permanent formwork filled with SFCB concrete prefabricated pipe pile

Abstract

The invention provides a prefabricated pipe pile with an ultrahigh-performance geopolymer concrete permanent formwork filled with SFCB concrete and a preparation method of the prefabricated pipe pile. The pipe pile is characterized in that the ultrahigh-performance geopolymer concrete permanent formwork serves as an outer pipe; the ultrahigh-performance geopolymer concrete permanent formwork serves as an inner pipe, and the outer pipe is arranged outside the inner pipe in a sleeving mode. The composite material grids are respectively arranged in the middle positions of the outer pipe and the inner pipe; the common concrete is poured between the outer pipe and the inner pipe; the SFCB straight bars are arranged in the common concrete; and the FRP spiral stirrups surround the outer sides of the SFCB straight ribs. The pipe pile is good in durability and anti-seismic toughness and has the advantages of being environmentally friendly and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering, and in particular relates to a prefabricated pipe pile filled with SFCB concrete in a permanent formwork of ultra-high performance geopolymer concrete and a preparation method thereof. Background Art

[0002] Existing prefabricated concrete pipe piles generally use steel or FRP as reinforcement materials. For example, CN112663596A provides a prestressed FRP bundle steel cylinder concrete pipe pile foundation structure, including an internal prestressed concrete pipe pile, a sieve-type steel pipe, concrete material, a steel cylinder, a zinc-aluminum alloy coating, a prestressed FRP bundle layer and a resin-rich layer. CN111335298A discloses a hybrid high-strength concrete pipe pile, including a concrete pile body, a steel cage built into the concrete pile body, and an FRP pipe wrapped outside the concrete pile body.

[0003] For concrete pipe piles serving in marine environments, using steel as a reinforcement material will face serious steel corrosion problems, which will greatly reduce the service life of concrete pipe piles. In addition, under the action of earthquakes, the residual deformation of such pipe piles is large and cannot be quickly repaired. Using FRP as a reinforcement material can avoid the durability problem caused by steel corrosion, but it will make the concrete pipe piles insufficient in terms of seismic energy dissipation capacity, and FRP materials also face the problem of mechanical property degradation in marine corrosive environments. In addition, under the environmental effects of chloride ions, sulfate erosion and freeze-thaw cycles, the durability of ordinary concrete cannot be guaranteed.

[0004] Therefore, it is of great significance to develop a new type of prefabricated concrete pipe pile suitable for marine environment, with durability and seismic toughness. Summary of the invention

[0005] The purpose of the present invention is to provide a high-performance geopolymer concrete permanent formwork filled SFCB concrete prefabricated pipe pile and a preparation method thereof, so as to improve the durability and seismic toughness of existing concrete piles, and have the advantages of environmental protection and low cost.

[0006] The technical solution adopted by the present invention is: An ultra-high performance geopolymer concrete permanent formwork filled with SFCB concrete prefabricated pipe pile, comprising: Ultra-high performance geopolymer concrete permanent formwork as the outer tube; The ultra-high performance geopolymer concrete permanent formwork is used as the inner tube, and the outer tube is sleeved on the outside of the inner tube; The composite material grids are respectively arranged in the middle positions of the outer tube and the inner tube; Ordinary concrete, poured between the outer and inner tubes; SFCB straight bars are laid in ordinary concrete; and FRP spiral stirrups surround the outside of the SFCB straight bars.

[0007] Furthermore, the thickness of the outer tube and the inner tube are both 20 to 50 mm.

[0008] Furthermore, the inner surface of the outer tube and the outer surface of the inner tube are both connected to ordinary concrete by roughening.

[0009] Furthermore, the single layer thickness of the composite material grid is 2-5 mm, the mesh size is 50×50 mm or 100×100 mm, the number of layers is 1 or more, and the multiple layers of composite material grid are stacked.

[0010] Furthermore, the diameter and spacing of the FRP spiral stirrups are determined by the external loads; and the reinforcement amount of the SFCB straight bars is determined by the external loads and earthquake effects.

[0011] Furthermore, the SFCB straight bars are arranged inside the FRP spiral stirrups and are evenly distributed.

[0012] Furthermore, the grade of the ordinary concrete is C20-C80.

[0013] Furthermore, the composite material used to prepare the composite mesh, FRP spiral stirrups and SFCB straight bars is AFRP, BFRP, CFRP or GFRP.

[0014] Furthermore, the pipe pile has a circular hollow cross-section.

[0015] The method for preparing any one of the above-mentioned ultra-high performance geopolymer concrete permanent formwork filled with SFCB concrete prefabricated pipe piles comprises the following steps: S1, preparing a template for preparing an inner tube and an outer tube; S2, placing composite material grids in the templates of the inner tube and the outer tube respectively; S3, preparing ultra-high performance geopolymer concrete slurry, and pouring it into the inner tube formwork and the outer tube formwork respectively, performing water bath curing, and demoulding after the curing is completed to obtain the outer tube and the inner tube; S4, roughening the inner surface of the outer tube and the outer surface of the inner tube, and fitting the outer tube and the inner tube; S5. Tie FRP spiral stirrups and SFCB straight bars to form a skeleton, place the skeleton between the outer tube and the inner tube, pour ordinary concrete, and place it in a standard curing room for curing. After the curing is completed, demoulding is performed to complete the preparation of the pipe pile.

[0016] The beneficial effects of the present invention are: (1) An inner tube of an ultra-high performance geopolymer concrete permanent formwork and an outer tube of an ultra-high performance geopolymer concrete permanent formwork are used as the pile matrix, and a composite material grid is arranged in the middle position between the inner tube and the outer tube. The ultra-high performance geopolymer concrete permanent formwork reinforced with the composite material grid has a high density, which can effectively prevent the invasion of corrosive media, improve the durability of the component, and take into account the advantages of wear resistance, environmental protection and low cost; and the mechanical properties of the ultra-high performance geopolymer concrete permanent formwork can be further improved to meet the requirements of a thin-walled component.

[0017] (2) By pouring ordinary concrete between the inner tube and the outer tube, SFCB straight bars and FRP spiral stirrups are added to the ordinary concrete. The SFCB straight bars and FRP spiral stirrups can provide secondary stiffness for the components. The composite grid strengthens the constraint of the permanent formwork of ultra-high performance geopolymer concrete, so that the pipe pile has sufficient energy dissipation capacity under earthquake action, while showing small residual deformation and having good seismic toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the cross-sectional structure of a pipe pile according to Example 1 of the present invention.

[0019] Figure 2 This is a three-dimensional structural diagram of the pipe pile of Example 1 of the present invention with a layer of the outer pipe surface removed.

[0020] Reference numerals: 1. outer tube; 2. inner tube; 3. composite material grid; 4. ordinary concrete; 5. FRP spiral stirrups; 6. SFCB straight bars. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below through detailed embodiments in conjunction with the accompanying drawings. Example 1

[0022] The present invention provides a prefabricated pipe pile filled with SFCB concrete in a permanent formwork of ultra-high performance geopolymer concrete, such as Figure 1 and Figure 2 As shown, the prefabricated pipe pile is composed of an outer pipe 1, an inner pipe 2, a composite material grid 3, ordinary concrete 4, FRP spiral stirrups 5 and SFCB straight bars 6.

[0023] The outer tube 1 and the inner tube 2 are both made of ultra-high performance geopolymer concrete permanent formwork. The two ultra-high performance geopolymer concrete permanent formworks are sleeved together, one is located on the inside and the other is located on the outside; the SFCB straight reinforcement is arranged on the inside of the FRP spiral stirrups, and a skeleton is formed by tying, which is placed between the two ultra-high performance geopolymer concrete permanent formworks, and ordinary concrete is poured in between.

[0024] The cross section of the pipe pile is circular, and its size can be determined according to the needs of the actual project. The thickness of the outer tube 1 and the inner tube 2 is determined according to the environment, preferably 20 to 40 mm; there is a diameter difference between the two permanent formworks to provide enough space to place the skeleton, and there should be a certain distance between the skeleton and the permanent formwork to ensure the uniform distribution of the coarse aggregate of ordinary concrete; the effective area of ​​the cross section of the pipe pile should be determined according to the force requirements.

[0025] The inner surface of the outer tube and the outer surface of the inner tube are both connected to the ordinary concrete by roughening, so as to improve the connection performance between the inner tube and the outer tube and the ordinary concrete. The grade of the ordinary concrete 2 is preferably C20-C80.

[0026] The composite material grid 3, FRP spiral stirrups 5, and SFCB straight bars 6 are all existing technologies, and preferably the composite materials used are AFRP materials, BFRP materials, CFRP materials or GFRP materials.

[0027] Preferably, the single layer thickness of the composite material grid 3 is 2-5 mm, the mesh size is 50×50 mm or 100×100 mm, and the composite material grid single layer or multiple layers are stacked and arranged in the middle position of the outer tube 1 and the inner tube 2, and connected in an overlapping manner along the circumferential direction.

[0028] The diameter and spacing of the FRP spiral stirrups 5 are determined by the external loads, and preferably the diameter is 6 to 12 mm. The reinforcement amount of the SFCB straight bars 6 is determined by the external loads and earthquake effects, and preferably the diameter is 12 to 28 mm.

[0029] Specifically, in this embodiment; The outer diameter of the pile cross section is 600mm, and the pile length is 8m. The thickness of the outer pipe 1 is 40mm, and a layer of composite material mesh 3 with a thickness of 5mm is arranged in the middle position of its thickness direction, that is, about 17.5mm away from the outer surface of the outer pipe; the outer diameter of the inner pipe 2 is 180mm, and the thickness is 30mm. A layer of composite material mesh 3 with a thickness of 3mm is arranged in the middle position of its thickness direction, that is, about 13.5mm away from the inner surface of the inner pipe; the mesh size of the composite material mesh 3 is 50×50 mm, and it is connected in an overlapping manner along the circumferential direction, and the overlapping length is two mesh sizes.

[0030] The diameter of the FRP spiral stirrup 5 is 10 mm, the outer diameter is 235 mm, the pitch is 150 mm, the tensile strength is 1400 MPa, and the elastic modulus is 55 GPa; the diameter of the SFCB straight bar 6 (internal wrapped with a diameter of 16 and grade HRB400 steel bars) is 20 mm, the layout spacing is 40 mm, and there are 32 bars in total. The yield strength is 260 MPa, the tensile strength is 720 MPa, and the elastic modulus is 106 GPa.

[0031] The grade of the ordinary concrete 2 used is C40, and its cubic block compressive strength is 52 MPa.

[0032] The ultra-high performance geopolymer concrete used contains powdered blast furnace slag (850 kg / m 3 )、Silica fume(280 kg / m 3 )、quartz sand(850 kg / m 3 )、Sodium hydroxide solution (100 kg / m 3 )、Sodium silicate solution (300 kg / m 3 ), steel fiber (diameter 0.2 mm, length 13 mm, volume fraction 1.75%).

[0033] The composite materials in the composite material grid 3, FRP spiral stirrups 5, and SFCB straight bars 6 are all made of basalt fiber and epoxy resin. The composite material grid 3, FRP spiral stirrups 5, and SFCB straight bars 6 are existing technologies and can be purchased on the market. The method for preparing the SFCB concrete prefabricated pipe pile filled with ultra-high performance geopolymer concrete permanent formwork described in Example 1 comprises the following steps:

[0034] S1, preparing a template for preparing the outer tube 1 and the inner tube 2 of the permanent shell; S2, placing the composite material grid 3 in the middle of the templates of the inner tube 1 and the outer tube 2 of the permanent shell respectively; S3, prepare ultra-high performance geopolymer concrete slurry, and pour it into the templates of the inner tube 2 and the outer tube 1 of the permanent shell respectively, perform water bath curing, and demould after the curing is completed to obtain the outer tube 1 and the inner tube 2; S4, roughening the inner surface of the outer tube 1 and the outer surface of the inner tube 2, and inserting the inner tube 2 into the outer tube 1; S5, tie FRP spiral stirrups 5 and SFCB straight bars 6, with the SFCB diameter 6 located inside the FRP spiral stirrups 5 to form a skeleton, place it between the outer tube 1 and the inner tube 2, pour ordinary concrete 4) and place it in a standard curing room for curing. After the curing is completed, demoulding is performed to complete the preparation of the pipe pile.

[0035] The performance of the pipe pile of Example 1 is as follows: The chloride ion diffusion coefficient of the ultra-high performance geopolymer concrete cast in step 3 was tested by the rapid chloride ion migration test method and the alternating current method, and was 0.012×10-12m 2 / s, resistivity is 422 kΩ·cm, and it has excellent durability.

[0036] The damping coefficient of the pipe pile tested by the quasi-static loading method is 0.03, the stiffness coefficient after yield is 10%, and the residual displacement angle is 0.1%. The pipe pile of the present invention exhibits good seismic energy dissipation capacity and toughness.

[0037] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications are also within the scope of protection of the present invention.

Claims

1. A prefabricated SFCB concrete pile filled with an ultra-high performance geopolymer concrete permanent formwork, characterized in that: include: Ultra-high performance geopolymer concrete permanent formwork as the outer tube (1); The ultra-high performance geopolymer concrete permanent formwork is used as the inner tube (2), and the outer tube (1) is sleeved on the outside of the inner tube (2); Composite material grids (3) are respectively arranged at the middle positions of the outer tube (1) and the inner tube (2); Ordinary concrete (4) is poured between the outer tube (1) and the inner tube (2); SFCB straight bars (6) are arranged in ordinary concrete (4); and The FRP spiral stirrups (5) surround the outside of the SFCB straight bars (6).

2. The SFCB concrete prefabricated pipe pile filled with ultra-high performance geopolymer concrete permanent formwork according to claim 1 is characterized in that: The thickness of the outer tube (1) and the inner tube (2) are both 20 to 50 mm.

3. The ultra-high performance geopolymer concrete permanent formwork filled SFCB concrete prefabricated pipe pile according to claim 1, characterized in that: The inner surface of the outer tube (1) and the outer surface of the inner tube (2) are both connected to ordinary concrete (4) by roughening.

4. The ultra-high performance geopolymer concrete permanent formwork filled SFCB concrete prefabricated pipe pile according to claim 1, characterized in that: The single layer thickness of the composite material grid (3) is 2-5 mm, the mesh size is 50×50 mm or 100×100 mm, the number of layers is 1 or more, and the multiple layers of composite material grid are stacked.

5. The ultra-high performance geopolymer concrete permanent formwork filled SFCB concrete prefabricated pipe pile according to claim 1, characterized in that: The diameter and spacing of the FRP spiral stirrups (5) are determined by the external loads; and the reinforcement amount of the SFCB straight bars (6) is determined by the external loads and earthquake effects.

6. The SFCB concrete prefabricated pipe pile filled with ultra-high performance geopolymer concrete permanent formwork according to claim 5, characterized in that: The SFCB straight bars (6) are arranged inside the FRP spiral stirrups (5) and are evenly distributed.

7. The ultra-high performance geopolymer concrete permanent formwork filled SFCB concrete prefabricated pipe pile according to claim 1, characterized in that: The grade of the ordinary concrete (4) is C20-C80.

8. The ultra-high performance geopolymer concrete permanent formwork filled SFCB concrete prefabricated pipe pile according to claim 1, characterized in that: The composite material used to prepare the composite material grid (3), the FRP spiral stirrups (5) and the SFCB straight bars (6) is AFRP, BFRP, CFRP or GFRP.

9. The ultra-high performance geopolymer concrete permanent formwork filled SFCB concrete prefabricated pipe pile according to claim 1, characterized in that: The pipe pile has a circular hollow section.

10. The method for preparing the SFCB concrete prefabricated pipe pile filled with ultra-high performance geopolymer concrete permanent formwork according to any one of claims 1 to 9, characterized in that: The steps include: S1, preparing a template for making the inner tube (2) and the outer tube (1); S2, placing composite material grids (3) in the templates of the inner tube (2) and the outer tube (1), respectively; S3, preparing ultra-high performance geopolymer concrete slurry, and pouring it into the inner tube formwork and the outer tube formwork respectively, and performing water bath curing, and demoulding after the curing is completed to obtain the outer tube (1) and the inner tube (2); S4, roughening the inner surface of the outer tube (1) and the outer surface of the inner tube (2), and fitting the outer tube (1) and the inner tube (2); S5, tying FRP spiral stirrups (5) and SFCB straight bars (6) to form a skeleton, placing the skeleton between the outer tube (1) and the inner tube (2), pouring ordinary concrete (4), placing the skeleton in a standard curing room for curing, and demoulding after the curing is completed, thereby completing the preparation of the pipe pile.

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