A high ductility fiber reinforced polymer tendon and preparation method thereof

Abstract

The present invention discloses a high-ductility fiber-reinforced polymer tendon and a preparation method thereof, and relates to the field of fiber-reinforced composite materials. The high-ductility fiber-reinforced polymer tendon includes the following components in volume fraction: polyvinyl alcohol fiber 5-40wt%, aramid fiber 5%-40wt%, carbon fiber 5%-40wt%, resin 15-30wt%, curing agent 0.5-2.5wt%, accelerator 0.5%-2.5%, filler 2%-6%. The high-ductility fiber-reinforced polymer tendon uses polyvinyl alcohol fiber as the core, weaves aramid fiber three-dimensionally on its periphery, and then three-dimensionally weaves carbon fiber on the periphery of aramid fiber, impregnates through a thermosetting resin matrix, and then uses a mold forming device with ribs to preliminarily form and pultrude, heat and cure, and cut to obtain a high-ductility fiber-reinforced polymer tendon of the required size. This material has good ductility and yield properties, can be widely used in the field of concrete structure engineering, and solves the problem of low ductility of FRP tendons.

Description

Technical Field

[0001] The invention relates to the technical field of reinforcing materials for concrete structures, in particular to a high-ductility fiber-reinforced polymer tendon and a preparation method thereof. Background Art

[0002] As a traditional material in the field of concrete structures, steel bars are often exposed to corrosive environments, such as deicing salt or seawater, during construction projects. This can lead to severe degradation of the structure due to steel bar corrosion, affect the durability of the concrete material, cause structural instability, and incur high maintenance costs.

[0003] Fiber reinforced polymer (FRP) is a high-performance material formed by mixing fiber materials and thermosetting resin matrix materials in a certain proportion and compounding them through a certain process. Due to its many excellent properties such as light weight, high strength, corrosion resistance and easy cutting, it is used as internal reinforcement of concrete structures and is widely used in the field of reinforcement and performance enhancement of civil engineering structures, especially in harsh environments and coastal areas, and has gradually become a promising alternative to steel bars.

[0004] With the continuous promotion and maturity of FRP applications, the utilization efficiency of FRP strength is becoming more and more sufficient. However, FRP is a linear elastic material. From the beginning of tension to failure, its constitutive relationship is a linear characteristic, which is completely different from the yield characteristics of steel bars. In addition, its ductility is low and the structure is prone to brittle fracture, which seriously restricts the application of FRP bars in the field of concrete. Therefore, a new high-ductility fiber-reinforced polymer bar is needed to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a high-ductility fiber reinforced polymer bar and a preparation method thereof, so as to improve the ductility and yield properties of FRP materials, thereby promoting the application of FRP bars in concrete structures.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A high ductility fiber reinforced polymer tendon, comprising the following components by volume fraction:

[0008]

[0009] Preferably, the high-ductility fiber-reinforced polymer tendon has polyvinyl alcohol fiber as the core, aramid fiber is three-dimensionally woven around the polyvinyl alcohol fiber, and carbon fiber is three-dimensionally woven around the aramid fiber.

[0010] Preferably, the resin is a mixture of one or more epoxy resins and vinyl resins.

[0011] Preferably, the curing agent is a mixture of one or more of an amine curing agent and an acid anhydride curing agent.

[0012] Preferably, the promoter is a mixture of one or more of triethanolamine, cobalt isooctanoate and cobalt naphthenate.

[0013] Preferably, the filler is a mixture of one or more of calcium carbonate, nano silicon carbide and silicon dioxide.

[0014] A method for preparing a high-ductility fiber-reinforced polymer tendon comprises the following steps:

[0015] (1) using a three-dimensional weaving device, with polyvinyl alcohol fiber as the core, aramid fiber three-dimensionally weaved around the polyvinyl alcohol fiber, and carbon fiber three-dimensionally weaved around the aramid fiber, to perform preliminary molding;

[0016] (2) mixing the resin, curing agent, accelerator and filler in a uniform proportion to form a liquid phase of the thermosetting resin system;

[0017] (3) using an impregnation device, fully impregnating the polyvinyl alcohol fiber, aramid fiber and carbon fiber preliminarily formed in step (1) in the liquid phase of the resin system in step (2), and eliminating bubbles;

[0018] (4) forming the carbon fiber, aramid fiber and polyvinyl alcohol fiber after the resin impregnation treatment in step (3) by using a mold forming device, and obtaining an initial fiber-reinforced polymer tendon by using a pultrusion forming device;

[0019] (5) The initial fiber-reinforced polymer tendons obtained in step (4) are heated and cured by a heating and curing device, and high-ductility fiber-reinforced polymer tendons are obtained by a cutting device.

[0020] Preferably, the mold forming device in step (4) is a mold forming device with ribs.

[0021] Preferably, the heating curing temperature in step (5) is 80 to 160°C.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The high-ductility fiber-reinforced polymer bar of the present invention makes full use of the high tensile strength and elastic modulus of carbon fiber, the impact resistance of aramid fiber, and the corrosion resistance and high mechanical strength of polyvinyl alcohol fiber. Compared with ordinary FRP bars, the tensile modulus and shear strength are significantly improved, and the bar has obvious yield performance. In addition, the ribs on the surface of the polymer bar help to increase the bond strength between the polymer bar and the cement matrix, making the bonding performance better and increasing the interlayer shear strength. It can be widely used in the field of construction engineering and the support and anchoring fields of mines, tunnels, slopes, pits, etc., and has more advantages than steel bars and ordinary FRP bars. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the cross-sectional structure of a high ductility fiber reinforced polymer tendon;

[0025] Figure 2 It is a schematic diagram of the preparation process of high ductility fiber reinforced polymer tendons;

[0026] Figure 3 It is a constitutive relationship curve diagram of the high ductility fiber reinforced polymer bars prepared in Examples 1-5 and ordinary commercially available FRP bars.

[0027] Markings in the figure: 1. polyvinyl alcohol fiber, 2. aramid fiber, 3. carbon fiber, 4. surface ribs (Note: there is a thermosetting resin matrix between the fibers). DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments to help understand the content of the present invention, but the present invention is not limited to these embodiments. The methods used in the present invention are all conventional methods unless otherwise specified; the raw materials and devices used are all conventional commercial products unless otherwise specified.

[0029] The formula components and volume fractions of the high ductility fiber reinforced polymer bars described in Example 1, Example 2, Example 3, Example 4, and Example 5 are shown in Tables 1 to 5:

[0030] Table 1

[0031]

[0032] Table 2

[0033]

[0034] Table 3

[0035]

[0036] Table 4

[0037]

[0038] Table 5

[0039]

[0040] like Figure 2 As shown, the method for preparing the high ductility fiber reinforced polymer tendons described in the above embodiments 1-5 comprises the following steps:

[0041] (1) using a three-dimensional weaving device, with polyvinyl alcohol fiber as the core, aramid fiber three-dimensionally weaved around the polyvinyl alcohol fiber, and carbon fiber three-dimensionally weaved around the aramid fiber, to perform preliminary molding;

[0042] (2) mixing the resin, curing agent, accelerator and filler in a uniform proportion to form a liquid phase of the thermosetting resin system;

[0043] (3) using an impregnation device, fully impregnating the polyvinyl alcohol fiber, aramid fiber and carbon fiber preliminarily formed in step (1) in the liquid phase of the resin system in step (2), and eliminating bubbles;

[0044] (4) forming the carbon fiber, aramid fiber and polyvinyl alcohol fiber after the resin impregnation treatment in step (3) by using a mold forming device with ribs, and continuously pulling the product out through a pultrusion forming device to obtain an initial fiber-reinforced polymer tendon;

[0045] (5) The initial fiber-reinforced polymer tendons obtained in step (4) are heated and cured by a heating and curing device at a temperature of 80 to 160° C., and are cut into required product lengths by a cutting device, thereby finally obtaining high-ductility fiber-reinforced polymer tendons.

[0046] Product Structure

[0047] like Figure 1 As shown, the core part of the high-ductility fiber-reinforced polymer tendon is polyvinyl alcohol fiber 1; the middle layer part is aramid fiber 2; the outer layer part is carbon fiber 3, and the outermost part is the surface ribs 4 of the polymer tendon. The surface ribs 4 significantly increase the contact area with the cement matrix, thereby increasing the bonding strength between the polymer tendon and the cement matrix.

[0048] Performance Testing

[0049] like Figure 3 As shown, the high ductility fiber reinforced polymer bars prepared in the above examples 1-5 and the common commercially available FRP bars as a comparative example were tested on a universal testing machine to obtain the constitutive relationship curves Figure 3. The curve shows that after the high-ductility fiber-reinforced polymer tendons are subjected to stress, they exhibit a certain linearity, followed by an obvious yield stage until they are destroyed. The constitutive relationship curve clearly shows the yield strength, yield strain, ultimate strength and ultimate strain of the high-ductility fiber-reinforced polymer tendons, which have many similarities with steel bars. The experimental results show that the yield strength of the high-ductility fiber-reinforced polymer tendons reaches more than 800MPa, the ultimate strain reaches more than 3.3%, and the ultimate strength is about 1.3 times the yield strength; after calculation, its linear segment elastic modulus reaches about 90Gpa.

[0050] According to actual test results, compared with ordinary FRP bars, the high ductility fiber reinforced polymer bars of the present invention have the following obvious advantages:

[0051] (1) The shear strength and tensile elastic modulus of high-ductility fiber-reinforced polymer tendons are significantly improved.

[0052] (2) The formation of surface ribs significantly improves the bonding strength between the high-ductility fiber-reinforced polymer tendons and the cement matrix.

[0053] (3) The high tensile strength and elastic modulus of carbon fiber, the impact resistance and high modulus of aramid fiber, and the corrosion resistance, high mechanical strength, and high ultimate elongation of polyvinyl alcohol fiber are fully utilized to improve the tensile strength, elastic modulus, and durability of the high-ductility fiber-reinforced polymer tendons without increasing the cost much, making them suitable for more fields.

[0054] (4) The high-ductility fiber-reinforced polymer tendons of the present invention have a yield stage when subjected to stress, and have obvious yield strength, yield strain, ultimate strength, and ultimate strain, which make up for the weaknesses of ordinary FRP tendons and have a theoretical basis for directly utilizing the current reinforced concrete specifications.

[0055] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0056] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A high ductility fiber reinforced polymer tendon, characterized in that: Includes the following volume fraction meter components: The high-ductility fiber-reinforced polymer tendon has polyvinyl alcohol fiber as the core, aramid fiber is three-dimensionally woven around the polyvinyl alcohol fiber, carbon fiber is three-dimensionally woven around the aramid fiber, and the high-ductility fiber-reinforced polymer tendon has surface ribs around its periphery.

2. A high ductility fiber reinforced polymer tendon according to claim 1, characterized in that: The resin is a mixture of one or more epoxy resins and vinyl resins.

3. The high ductility fiber reinforced polymer tendon according to claim 1, characterized in that: The curing agent is a mixture of one or more of an amine curing agent and an acid anhydride curing agent.

4. The high ductility fiber reinforced polymer tendon according to claim 1, characterized in that: The accelerator is a mixture of one or more of triethanolamine, cobalt isooctanoate and cobalt naphthenate.

5. The high ductility fiber reinforced polymer tendon according to claim 1, characterized in that: The filler is a mixture of one or more of calcium carbonate, nano silicon carbide and silicon dioxide.

6. A method for preparing a high ductility fiber reinforced polymer tendon according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) using a three-dimensional weaving device, with polyvinyl alcohol fiber as the core, aramid fiber three-dimensionally weaved around the polyvinyl alcohol fiber, and carbon fiber three-dimensionally weaved around the aramid fiber, to perform preliminary molding; (2) mixing the resin, curing agent, accelerator and filler in a uniform proportion to form a liquid phase of the thermosetting resin system; (3) using an impregnation device, fully impregnating the polyvinyl alcohol fiber, aramid fiber and carbon fiber preliminarily formed in step (1) in the liquid phase of the resin system in step (2), and eliminating bubbles; (4) forming the carbon fiber, aramid fiber and polyvinyl alcohol fiber after the resin impregnation treatment in step (3) by using a mold forming device, and obtaining an initial fiber reinforced polymer tendon by a pultrusion forming device; wherein the mold forming device is a mold forming device with ribs; (5) The initial fiber-reinforced polymer tendons obtained in step (4) are heated and cured by a heating and curing device, and high-ductility fiber-reinforced polymer tendons are obtained by a cutting device.

7. The method for preparing a high ductility fiber reinforced polymer tendon according to claim 6, characterized in that: The heating curing temperature in step (5) is 80 to 160°C.

Images