FRP composite pipe and application thereof

Abstract

The invention discloses an FRP composite pipe and application thereof, the FRP composite pipe comprises an FRP pipe and an adhesion layer adhered to the inner wall of the FRP pipe, and a steel wire is further arranged between the FRP pipe and the adhesion layer; wherein the tensile strength of the steel wire is greater than or equal to 1400 MPa. The FRP composite pipe provided by the invention has excellent lateral pressure resistance, material ductility, circumferential tensile strength and the like, has good adhesive property with concrete, and is suitable for being used as a permanent template in road facilities, bridges, tunnels, industrial buildings, civil buildings and the like. Meanwhile, the FRP composite pipe also has excellent corrosion resistance, can effectively resist air, moisture, chloride ion permeation and the like, and is also suitable for being applied to a marine environment concrete structure.

Description

Technical Field

[0001] The present invention relates to the technical fields of civil engineering and ocean engineering, and particularly relates to an FRP composite pipe and its application. Background Art

[0002] Formwork engineering is one of the key links in the construction process of concrete structures, and has a significant impact on the quality, safety, progress and economic benefits of construction projects. In conventional concrete structures, the cost of traditional formwork engineering accounts for about 20%-30% of the total cost. Compared with traditional formwork, fiber reinforced resin (referred to as "composite material", English: Fiber Reinforced Polymer, English abbreviation "FRP") formwork has superior properties such as light weight, high strength, and corrosion resistance, and has been more and more widely used in new road projects, bridge and tunnel projects, industrial and civil building projects. Applying FRP pipes as permanent formwork in concrete structures can effectively improve the service performance and durability of concrete structures; in addition, FRP pipes can produce a confinement effect on concrete and enhance the bearing capacity and ductility of concrete structures. As permanent formwork, FRP pipes have been preliminarily applied in new concrete structure projects and have achieved remarkable social and economic benefits. Moreover, FRP pipes also have excellent corrosion resistance and can effectively resist the penetration of air, moisture and chloride ions. According to literature reports, a 3-mm-thick resin-rich layer can effectively prevent chloride ion penetration within 50 years. Therefore, in a marine environment, FRP pipes are particularly suitable as permanent formwork for concrete structures.

[0003] Currently, FRP pipes are mainly applied to compression and bending members, such as concrete beams, slabs, columns, and concrete arch structures, as co-bearing materials to improve the long-term and short-term service performance and bearing capacity of concrete structures. The circumferential tensile strength of current pure FRP pipes used as permanent formwork has certain advantages compared with ordinary steel formwork. In compression and bending members, they mainly provide the concrete confinement effect and anti-permeability effect. However, in large members, the requirements for wall thickness of the confinement effect and anti-permeability of pure FRP pipes do not match, resulting in waste of FRP pipes and reducing the economic advantages of FRP pipes in the application of large members.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the Invention

[0005] In view of the above deficiencies of the prior art, the present invention provides an FRP composite pipe and its application to solve the problem that the requirements for wall thickness of the confinement effect and anti-permeability of existing pure FRP pipes do not match, resulting in waste of pure FRP pipes and reducing the economic advantages of pure FRP pipes in the application of large members.

[0006] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0007] In the first aspect of the present invention, an FRP composite pipe is provided. The FRP composite pipe includes an FRP pipe and an attachment layer bonded to the inner wall of the FRP pipe, and steel wires are also provided between the FRP pipe and the attachment layer.

[0008] Among them, the tensile strength of the steel wire is greater than or equal to 1400 MPa.

[0009] Preferably, the FRP pipe is prepared from long fibers and a first resin, and the first resin is one of epoxy resin, vinyl resin, and polyester resin.

[0010] Preferably, in the FRP pipe, the mass fraction of the long fibers is greater than 40%, and the long fibers are one or more of glass fibers, carbon fibers, basalt fibers, and aramid fibers.

[0011] Preferably, the thickness of the FRP pipe is less than or equal to 6 mm.

[0012] Preferably, the steel wires are arranged along the axial direction of the FRP pipe, and the steel wires are spirally distributed.

[0013] Preferably, the steel wire is a spiral steel wire, and the cross-sectional diameter of the spiral steel wire is less than or equal to 12 mm.

[0014] Preferably, the attachment layer is prepared by mixing quartz sand and a second resin; the second resin is one of epoxy resin, vinyl resin, and polyester resin.

[0015] Preferably, in the attachment layer, the mass fraction of the quartz sand is not less than 70%, and the maximum particle size of the quartz sand is less than or equal to the spiral pitch of the spiral steel wire and greater than or equal to the thickness of the attachment layer.

[0016] Preferably, the thickness of the attachment layer is greater than or equal to 1 mm and less than or equal to 1 / 2 of the cross-sectional diameter of the steel wire.

[0017] In the second aspect of the present invention, the application of the above FRP composite pipe in road facilities, bridge and tunnel facilities, industrial building facilities, civil building facilities, and marine facilities is provided.

[0018] Beneficial effects:

[0019] The present invention discloses an FRP composite pipe and its application. Traditional pure FRP pipes are composed of long fibers and resin. Among them, the resin has chemical properties of corrosion resistance and anti - permeability, but its own mechanical properties are poor. The long fibers have excellent mechanical properties and can provide a confinement effect on concrete mechanically. However, multiple long fibers need to be bonded by the resin matrix to jointly bear force. Therefore, the volume ratio of resin and long fibers in the pure FRP pipe basically remains around 1:1. To meet the chemical functions of corrosion resistance and anti - permeability, a 3 - mm - thick pure FRP pipe can effectively prevent chloride ion penetration within 50 years. To achieve the concrete confinement effect mechanically, the diameter - to - thickness ratio of the pure FRP pipe should not be greater than 200. In large - scale components, the wall thickness of the pure FRP pipe will far exceed the wall thickness required for anti - permeability. This mismatch between the concrete confinement effect and the anti - permeability requirements in terms of the FRP pipe wall thickness results in waste of FRP pipes. Compared with traditional pure FRP pipes, the FRP pipe in the FRP composite pipe provided by the present invention mainly functions to fix steel wires, resist corrosion, prevent penetration, and improve the service performance of concrete structures as a permanent formwork, and no longer mainly bears the confinement effect. Instead, the steel wires in the FRP composite pipe replace the long fibers in the pure FRP pipe to provide the main confinement effect.

[0020] In the FRP composite pipe provided by the present invention, the wall thickness of the FRP pipe is no longer restricted by the diameter - to - thickness ratio requirement of the confinement effect and is relatively thin. The FRP composite pipe successfully solves the problem of mismatch between the confinement effect and anti - permeability requirements in the wall thickness of traditional pure FRP pipes and has significant economic advantages. In addition, the tensile strength of the steel wire is not less than 1400 MPa, the elastic modulus reaches about 200 GPa, and it has high ductility, which can effectively reduce stress concentration, further exert the strength of the fiber material in the FRP composite pipe, and significantly improve the circumferential stress - bearing performance of the composite pipe. The steel wire, as the inner ring rib of the FRP pipe, effectively improves the lateral pressure resistance performance of the FRP composite pipe. Finally, in the FRP composite pipe provided by the present invention, the inner - side steel wire can provide a confinement effect, reducing the amount of FRP pipe used. The FRP pipe can provide an anti - penetration effect to prevent the inner - side steel wire from being corroded by the external environment, and the adhesive layer can firmly bond the inner - side steel wire and the FRP pipe, enabling the FRP pipe and the inner - side steel wire to act together as a whole.

[0021] The FRP composite pipe provided by the present invention has excellent performance such as lateral pressure resistance, material ductility, and circumferential tensile strength. Moreover, it has good bonding performance with concrete and is suitable for use as a permanent formwork in road facilities, bridges and tunnels, industrial buildings, civil buildings, etc. At the same time, the FRP composite pipe also has excellent corrosion resistance and can effectively resist air, moisture, and chloride ion penetration, etc., and is also suitable for application in marine - environment concrete structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1It is a schematic structural diagram of the circular FRP composite pipe provided in Embodiment 1 of the present invention;

[0023] Figure 2 It is a schematic longitudinal sectional structural diagram of the circular FRP composite pipe provided in Embodiment 1 of the present invention;

[0024] Figure 3 It is a schematic structural diagram of the square FRP composite pipe provided in Embodiment 2 of the present invention;

[0025] Figure 4 It is a schematic structural diagram of the elliptical FRP composite pipe provided in Embodiment 3 of the present invention;

[0026] Figure 5 It is a schematic structural diagram of the frustum-shaped FRP composite pipe provided in Embodiment 4 of the present invention;

[0027] Figure 6 It is a schematic structural diagram of the trapezoidal FRP composite pipe provided in Embodiment 5 of the present invention.

[0028] Among them, each reference numeral in the figure: 1, FRP pipe; 2, adhesion layer; 3, steel wire. Detailed implementation manners

[0029] The present invention provides an FRP composite pipe and its application. To make the purpose, technical solution and effect of the present invention clearer and more definite, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] Embodiments of the present invention provide an FRP composite pipe, as Figure 1 and Figure 2 shown, the FRP composite pipe includes an FRP pipe 1 and an adhesion layer 2 bonded to the inner wall of the FRP pipe 1, and a steel wire 3 is further provided between the FRP pipe 1 and the adhesion layer 2; wherein, the tensile strength of the steel wire 3 is greater than or equal to 1400 MPa.

[0031] First, the FRP tube 1 in the FRP composite tube mainly provides the functions of fixing the inner steel wire 3, anti-corrosion, anti-permeation, and improving the service performance of the concrete structure as a permanent formwork. The wall thickness of the FRP tube 1 is not restricted by the requirement of the diameter-thickness ratio of the restraint effect. Therefore, the FRP composite tube provided by the embodiment of the present invention has significant economic advantages. In addition, the steel wire 3 in the FRP composite tube replaces the long fiber in the pure FRP tube, provides the main restraint effect, reduces the resin dosage, and lowers the cost. At the same time, the tensile strength of the steel wire in the steel wire 3 is not less than 1400 MPa and the elastic modulus reaches about 200 GPa, which has high ductility, can effectively reduce stress concentration, further exert the strength of the fiber material in the FRP tube 1, and significantly improve the circumferential stress-bearing performance. Specifically, the steel wire 3 is made of ultra-high-strength steel wire. The ultra-high tensile strength and good ductility of the ultra-high-strength spiral steel wire can not only effectively provide a restraint effect for the concrete, but also serve as the inner rib of the FRP tube 1, significantly improving the lateral pressure resistance of the FRP composite tube as a formwork during the construction process. The steel wire 3 serves as the inner ring rib of the FRP tube 1, effectively improving the lateral pressure resistance of the FRP tube 1. In addition, the adhesion layer 2 in the FRP composite tube can firmly fix the FRP tube 1 and the inner steel wire 3, ensuring the working reliability of the FRP composite tube. The adhesion layer 2 and the steel wire 3 can effectively ensure the co-stress of the FRP composite tube and the concrete, inhibit the relative slip between the two and the shrinkage of the concrete.

[0032] In some embodiments, the dimensions of the FRP tube 1, the adhesion layer 2, and the steel wire 3 in the FRP composite tube of the embodiment of the present invention can be selected from common specifications, and can be specifically adjusted according to the required mechanical properties, corrosion resistance, and anti-permeation requirements.

[0033] In some specific embodiments, the thickness of the FRP tube 1 in the FRP composite tube is not greater than 6 mm, the cross-sectional diameter of the steel wire in the steel wire 3 is not greater than 12 mm, and the thickness of the adhesion layer 2 is not greater than 1 / 2 of the cross-sectional diameter of the steel wire in the steel wire 3.

[0034] In some embodiments, the inner contour of the FRP tube 1 is the same as the outer contour of the steel wire 3. These different outer contour shapes help the FRP composite tube to meet the requirements of the concrete structure project for the shape as a permanent formwork.

[0035] In some embodiments, the FRP tube 1 is prepared from long fibers and a first resin, and the first resin is one of epoxy resin, vinyl resin, and polyester resin. Using these resins as the matrix material of the FRP tube 1 plays a role in bonding the long fibers. The long fibers include at least one of glass fiber, carbon fiber, basalt fiber, and aramid; these long fibers can all improve the strength of the FRP tube 1, reduce the weight, improve the corrosion resistance, and improve the tensile, shear resistance and other properties.

[0036] In some embodiments, in the FRP pipe 1, the mass fraction of the long fibers is greater than 40%. The mass fraction of the long fibers ensures the mechanical properties of the FRP pipe 1.

[0037] In some embodiments, the steel wire 3 is a helical steel wire, and the cross-sectional diameter of the helical steel wire is less than or equal to 12 mm. The starting end of the helical steel wire is fixedly connected to the inner wall of one end of the FRP pipe 1, and then the helical steel wire extends along the inner wall of the FRP pipe 1 in a helical trajectory, with a uniform spacing between adjacent helical turns to ensure the formation of a stable and continuous helical structure inside the FRP1 pipe. The end of the helical steel wire is fixedly connected to the inner wall of the other end of the FRP pipe 1, so that the entire helical steel wire structure can be stably installed and positioned inside the pipe, forming an organic integral component with the pipe body.

[0038] In some embodiments, the adhesion layer 2 is prepared by mixing quartz sand and a second resin; the second resin is one of epoxy resin, vinyl resin, and polyester resin. The quartz sand particles in the adhesion layer 2 can increase the mechanical bite force and adhesion between the adhesion layer and the concrete. Through the synergistic effect of the quartz sand and the second resin, the FRP pipe 1 and the steel wire 3 are firmly fixed to form a whole. In addition, using these synthetic resins as the matrix material of the adhesion layer 2 plays a role in bonding the FRP pipe 1 and the steel wire 3, and at the same time has the effect of enhancing the corrosion resistance of the steel wire 3.

[0039] In some embodiments, the thickness of the adhesion layer is greater than or equal to 1 mm and less than or equal to 1 / 2 of the cross-sectional diameter of the strong helical steel wire. The minimum thickness requirement of the adhesion layer 2 ensures the firmness between the FRP pipe 1 and the steel wire 3, and the maximum thickness requirement ensures the uneven contour of the inner surface of the FRP composite pipe.

[0040] In some embodiments, the mass fraction of the quartz sand in the adhesion layer 2 is not less than 70%. This mass fraction ensures a sufficient degree of unevenness in the adhesion layer 2.

[0041] In some embodiments, the maximum particle size of the quartz sand in the adhesion layer 2 is not greater than the helical pitch of the steel wire 3 and not less than the thickness of the adhesion layer 2. The upper limit of the maximum particle size of the quartz sand ensures that the quartz sand can be distributed on the inner wall of the FRP pipe 1, and the lower limit of the maximum particle size of the quartz sand ensures that the quartz sand is not completely covered by the resin of the adhesion layer 2.

[0042] In some embodiments, the preparation steps of the FRP composite pipe include: First, prepare the FRP pipe 1 and the steel wire 3 respectively. The FRP pipe 1 is made by the fiber bundle winding process or the wet laying process of fiber cloth, and the steel wire 3 is made by cold coiling and processing of ultra-high strength steel wire; Assemble and fix the prepared FRP pipe 1 and the steel wire 3 into an assembly, then spray resin mortar into the FRP pipe 1, and rotate the assembly around the axis of the FRP pipe 1 to make the resin mortar evenly distributed on the inner wall of the FRP pipe 1 and the surface of the steel wire 3 by centrifugal force. Wait for the resin mortar to be completely cured. Under the bonding action of the completely cured resin mortar, the FRP pipe 1 and the steel wire 3 finally form an FRP composite pipe.

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments, and are only used to illustrate the present invention and in no way limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0044] Example 1

[0045] A circular FRP composite pipe, the structural schematic diagram thereof is as Figure 1 shown, and its longitudinal sectional structure diagram is as shown in the appendix Figure 2 shown. The circular FRP composite pipe includes: an FRP pipe 1, a spiral steel wire 3, and an adhesion layer 2 for fixing the steel wire 3 inside the FRP pipe 1. The length of the FRP pipe 1 is 450 mm, the inner diameter is 150 mm, the cross-sectional diameter of the spiral steel wire 3 is 3 mm, the spiral pitch is 3 mm, and the thickness of the adhesion layer 2 is 1.5 mm.

[0046] Example 2

[0047] An oval FRP composite pipe, the structural diagram thereof is as shown in the appendix Figure 3 shown. The difference between it and Example 1 is that the cross-sectional shape is square.

[0048] Example 3

[0049] A square FRP composite pipe, the structural diagram thereof is as shown in the appendix Figure 4 shown. The difference between it and Example 1 is that the cross-sectional shape is oval.

[0050] Example 4

[0051] A frustum-shaped FRP composite pipe, the structural diagram thereof is as shown in the appendix Figure 5 shown. The difference between it and Example 1 is that the size of the circular cross-section gradually changes along the axis of the pipe.

[0052] Example 5

[0053] A trapezoidal FRP composite pipe, the structure diagram of which is as attached Figure 6 as shown. The difference from Embodiment 1 is that the cross-sectional shape is rectangular and the cross-sectional dimensions gradually change along the pipe axis.

[0054] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. An FRP composite pipe, characterized in that, The FRP composite pipe includes an FRP pipe and an adhesion layer bonded to the inner wall of the FRP pipe, and steel wires are further arranged between the FRP pipe and the adhesion layer; wherein, the tensile strength of the steel wires is greater than or equal to 1400 MPa.

2. The FRP composite pipe according to claim 1, characterized in that, The FRP pipe is prepared from long fibers and a first resin, and the first resin is one of epoxy resin, vinyl resin, and polyester resin.

3. The FRP composite pipe according to claim 2, wherein, In the FRP pipe, the mass fraction of the long fibers is greater than 40%, and the long fibers are one or more of glass fibers, carbon fibers, basalt fibers, and aramid fibers.

4. The FRP composite pipe according to claim 1, characterized in that, The thickness of the FRP pipe is less than or equal to 6 mm.

5. The FRP composite pipe according to claim 1, wherein The steel wires are arranged along the axial direction of the FRP pipe, and the steel wires are spirally distributed.

6. The FRP composite pipe according to claim 5, wherein The steel wires are spiral steel wires, and the cross-sectional diameter of the spiral steel wires is less than or equal to 12 mm.

7. The FRP composite pipe according to claim 5, characterized in that, The adhesion layer is prepared by mixing quartz sand and a second resin; the second resin is one of epoxy resin, vinyl resin, and polyester resin.

8. The FRP composite pipe according to claim 7, wherein In the adhesion layer, the mass fraction of the quartz sand is not less than 70%, and the maximum particle size of the quartz sand is less than or equal to the spiral pitch of the spiral steel wires and greater than or equal to the thickness of the adhesion layer.

9. The FRP composite pipe according to claim 1, wherein, The thickness of the adhesion layer is greater than or equal to 1 mm and less than or equal to 1 / 2 of the cross-sectional diameter of the steel wires.

10. Application of the FRP composite pipe according to any one of claims 1-9 in road facilities, bridge and tunnel facilities, industrial building facilities, civil building facilities, and marine facilities.

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