High-corrosion-resistance retard-bonded prestressed tendon

Abstract

The invention discloses a high-corrosion-resistance retard-bonded prestressed tendon which comprises a steel wire harness, a plurality of reinforcing steel bars and a plurality of reinforcing steel bars, the steel wire harness is composed of seven steel wires, and the diameter of the steel wire harness ranges from 15.2 mm to 21.6 mm; the sheath is arranged outside the steel wire harness in a sleeving manner; and the retard-bonder filling layer is formed by filling a retard-bonder between the steel wire harness and the sheath, and the thickness of the retard-bonder filling layer is 1.0 mm to 1.25 mm. The high-corrosion-resistance retard-bonded prestressed tendon has high stress corrosion resistance, the minimum value of the internal stress corrosion test time of a solution A is 2 hours, the median value of the internal stress corrosion test time of the solution A is 5 hours or above, and the problems of structural durability and corrosion resistance of a prestressed material when a prestressed structure and an external prestressed tendon face the action of a complex environment can be effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical fields of concrete structures and wind power technologies, and particularly relates to a highly corrosion-resistant and slow-bonding prestressed tendon. Background Art

[0002] The prestressed application technology has been listed as one of the 10 key new technologies to be popularized and applied in the construction industry. Promoting the application of prestress in the fields of concrete structures and wind power technologies is of great significance for effectively utilizing natural resources, reducing carbon emissions, reducing material consumption, and improving the corrosion resistance and safety reserve of the bases and tower bodies of concrete structures and wind power technical facilities.

[0003] For prestressed structures, the durability of prestressed tendons has an important impact on the structural performance. Therefore, the durability guarantee rate of prestressed tendons should be higher than that of ordinary steel bars. Especially when the structure is under the action of a complex environment, simply improving the material quality and thickness of the concrete cover often cannot guarantee the design service life. For the "prestressed steel strand", which is a key component that is difficult to detect and repair during use, in addition to using prestressed materials with higher durability, multiple protection measures can also be taken through a combination method, such as using prestressed steel strands with higher stress corrosion resistance, or ultra-high stress corrosion-resistant slow-bonding prestressed steel bars, etc.

[0004] In the field of wind power technology, the currently used prestressed components such as anchor bolts or high-strength screw rods for wind turbine foundations are all unbonded prestressed structures. Generally, they are coated with dacromet on their outer surfaces for corrosion protection. During specific use, generally, a PVC pipe is sleeved on the outer surfaces of the anchor bolts and high-strength screw rods, so that the anchor bolts and high-strength screw rods are in an unbonded state with the concrete. After tensioning, a sealing treatment is performed on the top of the PVC pipe to prevent water from entering the PVC pipe. Usually, the waterproof sealing treatment process at the top of the PVC pipe is complex and has defects, and rainwater can enter the PVC pipe. Since dacromet loses its anti-corrosion ability when it encounters water, the prestressed components of the currently constructed foundations are severely corroded, seriously threatening the safety of wind turbine units.

[0005] Currently, the wind turbine towers mainly adopt external prestressed structures and prestressed cable forms. The used external prestressed tendons are directly in contact with the external environment, especially in the case of a relatively harsh corrosion environment such as the seaside. Therefore, it is urgent to improve the adaptability and corrosion resistance of this key component, the prestressed tendon, in the use environment and extend its service life.

[0006] The information disclosed in this background art section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art. Summary of the Invention

[0007] The object of the present invention is to provide a highly corrosion-resistant and slow-bonding prestressed tendon, which has high stress corrosion resistance performance.

[0008] To achieve the above object, the technical solution provided by a specific embodiment of the present invention is as follows:

[0009] A highly corrosion-resistant and slow-bonding prestressed tendon, comprising:

[0010] A steel wire bundle, composed of seven steel wires, and the diameter of the steel wire bundle is 15.2 mm - 21.6 mm;

[0011] A sheath, sleeved outside the steel wire bundle;

[0012] A slow-bonding agent filling layer, formed by filling a slow-bonding agent between the steel wire bundle and the sheath, and the thickness of the slow-bonding agent filling layer is 1.0 mm - 1.25 mm.

[0013] In one or more embodiments of the present invention, the steel wire bundle is composed of at least one of spiral rib steel wires, indented rib steel wires, and smooth round steel wires.

[0014] In one or more embodiments of the present invention, the steel wire bundle is composed of a first steel wire located at the center and six second steel wires arranged around the first steel wire.

[0015] In one or more embodiments of the present invention, the thickness of the sheath is 0.8 mm - 1.9 mm.

[0016] In one or more embodiments of the present invention, the material of the slow-bonding agent filling layer is an epoxy resin binder.

[0017] In one or more embodiments of the present invention, the minimum value of stress corrosion of the highly corrosion-resistant and slow-bonding prestressed tendon is 2.0 h, and the median value is 5.0 h or more.

[0018] In one or more embodiments of the present invention, the steel wire bundle is made of wire rods, and the chemical composition of the wire rods includes, by mass percentage, C 0.65 - 0.75%, Si 0.60 - 1.40%, Mn 0.20 - 0.80%, Cr 0.15 - 0.50%, Cu < 0.30%, Ni < 0.30%, Mo < 0.30%, V 0.02 - 0.05%, Nb 0.01 - 0.05%, S ≤ 0.008%, P ≤ 0.010%, N ≤ 0.0040%, O ≤ 0.0020%, and the rest is Fe and other inevitable impurities.

[0019] In one or more embodiments of the present invention, the production method of the wire rods includes steel melting, continuous casting, high-speed wire rolling, and controlled cooling after rolling processes;

[0020] Among them, in the high-speed wire rolling process, the billet obtained in the continuous casting process is heated and then rough rolled and finish rolled successively. The heating temperature is 1080 - 1150 °C, the starting rolling temperature of rough rolling is 950 - 1000 °C, the inlet temperature of finish rolling is 840 - 880 °C, and the wire laying temperature is 800 - 900 °C;

[0021] In the post-rolling controlled cooling process, online salt bath isothermal treatment and online aging treatment are adopted. In the online salt bath isothermal treatment, the salt bath temperature is 495 - 530 °C, and the salt bath time is 90 - 200 s; the online aging treatment is to place the wire rod after the online salt bath isothermal treatment in a heat preservation corridor, and the average cooling rate of the wire rod in the heat preservation corridor is not higher than 0.2 °C / s.

[0022] In one or more embodiments of the present invention, the wire rod is pickled, phosphated, drawn, stranded, and stabilized to obtain a steel wire harness;

[0023] Among them, the wire rod is pickled with a hydrochloric acid aqueous solution with a mass concentration of 15 - 20% for 7 - 10 min at a temperature of 35 - 42 °C;

[0024] The drawing is carried out in 9 - 11 passes, the area reduction rate per pass is 23% - 25%, the drawing speed is not higher than 2 m / s, and the temperature rise per pass is not higher than 100 °C;

[0025] The stranding tension is not less than 80 kN, and the speed is not higher than 36 m / min;

[0026] The stabilization temperature is 400 - 420 °C.

[0027] Compared with the prior art, the present invention uses the combination of a steel wire harness and a slow-bonding material to ensure the durability of the concrete structure and the external prestress under normal service conditions. The steel wire harness with higher stress corrosion resistance is selected from the material essence. The sheath and the steel wire harness are bonded into a whole through the slow-bonding agent filling layer. With the help of the stress corrosion resistance and high strength of the steel wire harness, the service life of the prestressed component is extended, and its safety performance within the designed service life is improved, providing a practical reference basis for the application of prestress technology and highly corrosion-resistant slow-bonding prestressed tendons in the fields of concrete structure engineering and wind power technology.

[0028] Tested according to the national standard "Test Methods for Steel Materials for Prestressed Concrete" GB / T 21839, the minimum stress corrosion test time of the highly corrosion-resistant slow-bonding prestressed tendon in the present invention in solution A is 2.0 hours, and the median value is more than 5 hours, effectively solving the problems of the durability of the prestressed structure and the corrosion resistance of the external prestressed tendon when facing complex environmental effects. Description of the Drawings

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0030] Figure 1 This is a schematic structural diagram of a highly corrosion-resistant and slow-bonding prestressed tendon in an embodiment of the present invention.

[0031] Main reference numerals description:

[0032] 1. Steel wire bundle; 2. Slow-bonding agent filling layer; 3. Sheath. Specific embodiments

[0033] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Since the steel wire bundle inside the slow-bonding prestressed tendon is coated with a slow-bonding material and wrapped with a sheath, it is difficult for the steel wire bundle to be corroded. At the same time, with the improvement of the manufacturing process level, the stress corrosion test time can meet higher corrosion resistance requirements. When the sheath of the slow-bonding prestressed tendon is not damaged, only part of the steel strands are exposed in the anchorage area of the entire slow-bonding prestressed tendon. Since the slow-bonding material is cured, the entire slow-bonding prestressed tendon can form a reliable bond with the concrete, and the anchorage area has little influence on the performance of the entire component during the use stage.

[0035] Therefore, a highly corrosion-resistant and slow-bonding prestressed tendon proposed by the present invention can better adapt to the action of complex environments and improve the durability requirements of concrete structures. Under the intrinsic high corrosion resistance of the prestressed tendon, the double protective layers of its outer sheath and slow-setting adhesive are beneficial to improving the corrosion resistance and performance stability of the prestressed components used in the wind power technology field.

[0036] Embodiment 1

[0037] A highly corrosion-resistant and slow-bonding prestressed tendon, as Figure 1As shown in the figure, it successively includes a sheath 3, a slow-bonding agent filling layer 2, and a steel wire bundle 1 from outside to inside. The material of the sheath 3 is high-density polyethylene, and the material of the slow-bonding agent filling layer 2 is epoxy resin binder. The epoxy resin binder is a conventional binder in the field, which can bond the sheath 3 and the steel wire bundle 1 into a whole. The steel wire bundle 1 is composed of seven spiral ribbed steel wires. Through the slow-bonding agent filling layer 2, the whole slow-bonding prestressed tendon forms a reliable bond with the concrete. At the same time, the steel wire bundle 1 has high corrosion resistance. Combining the double protection of the sheath 3 and the slow-bonding agent filling layer 2, the overall corrosion resistance of the slow-bonding prestressed tendon is improved, meeting the durability requirements of concrete structures.

[0038] Further, the diameter of the steel wire bundle 1 is 15.2 mm, the thickness of the slow-bonding agent filling layer 2 is 1.0 mm, and the thickness of the sheath 3 is 1 mm.

[0039] Further, the production method of the steel wire bundle is as follows:

[0040] (1) Steel melting process

[0041] The molten steel is smelted through the converter smelting and LF furnace refining steps carried out in sequence. The chemical composition of the molten steel at the end of smelting is as follows by mass percentage: C 0.75%, Si 0.60%, Mn 0.20%, Cr 0.50%, Cu 0.10%, Ni 0.10%, Mo <0.01%, V 0.02%, Nb 0.01%, S 0.006%, P 0.009%, N 0.0035%, O 0.0008%, and the rest are Fe and other inevitable impurities. In addition, the chemical composition of the continuous casting billet obtained in the continuous casting process and the chemical composition of the wire rod are consistent with the chemical composition of the molten steel at the end of the steel melting process.

[0042] Among them, in the converter smelting step, the hot metal is sent into the converter and mixed with scrap steel to form molten steel, and desiliconization, dephosphorization, and oxygen blowing decarburization are carried out. When tapping, alloys are added to the ladle for deoxidation alloying; in the refining step, the molten steel after converter smelting is sent into the LF refining furnace for chemical composition adjustment, temperature control, and the inclusions in the molten steel are controlled by soft stirring. After the temperature and chemical composition meet the standards, tapping is carried out.

[0043] (2) Continuous casting process

[0044] Small square billet continuous casting is adopted to cast the molten steel obtained in the steel melting process into a rectangular billet with a cross-sectional size of 180 mm × 240 mm.

[0045] Among them, the superheat of the molten steel is controlled at 20°C, the stirring current of the mold is 245 A, the stirring frequency of the mold is 2.5 Hz, the casting speed during continuous casting is 1.15 m / min, the specific water volume for continuous casting is 0.21 L / kg, the stirring current at the end is 425 A, the stirring frequency at the end is 7.5 Hz, and the total reduction of soft reduction is 14.8 mm.

[0046] (3) High-speed wire rolling process

[0047] The small billets obtained from the continuous casting process are heated and then subjected to rough rolling and finish rolling successively to prepare wire rods with a diameter of 15 mm. The heating temperature is 1150°C, the starting rolling temperature for rough rolling is 1000°C, the entry temperature for finish rolling is 850°C, and the laying temperature is 830°C.

[0048] (4) Post-rolling controlled cooling process

[0049] The wire rods after laying are directly immersed in a constant-temperature salt bath for isothermal treatment. The salt bath is molten nitrate, the temperature of the constant-temperature salt bath is 495°C, and the isothermal treatment time is 200 s. The wire rods after salt bath isothermal treatment immediately enter the heat preservation corridor for on-line aging treatment, and the average cooling rate during the on-line aging process of the wire rods is 0.15°C / s.

[0050] (5) Steel wire harness processing process

[0051] The wire rods are processed into steel wire harnesses through pickling, phosphating, drawing, stranding, and stabilization process pickling processes. Among them, the pickling uses an aqueous solution with a hydrochloric acid concentration of 19% (mass fraction), pickling for 8 minutes, at a temperature of 35 - 42°C, and the wire rods after pickling are placed for 24 hours before entering the next process. The drawing uses 11 passes, the area reduction rate per pass is 23%, the drawing speed is 2 m / s, and the temperature rise per pass is 100°C. The stranding tension is 80 kN, the speed is 36 m / min, and the stabilization temperature is 400°C.

[0052] Using the above production method, steel wire harnesses with a minimum stress corrosion time of 8.5 hours and a median of 12.5 hours can be prepared, and thus high corrosion-resistant and slow-bonded prestressing tendons with a minimum stress corrosion time of 2.0 h and a median value of more than 5.0 h can be prepared.

[0053] Example 2

[0054] The difference between this example and Example 1 is that the diameter of the steel wire harness is 17.8 mm, the thickness of the slow-bonding agent filling layer is 1.0 mm, and the thickness of the sheath 3 is 1.5 mm.

[0055] Example 3

[0056] The difference between this example and Example 1 is that the diameter of the steel wire harness is 21.6 mm, the thickness of the slow-bonding agent filling layer is 1.2 mm, and the thickness of the sheath 3 is 1.9 mm.

[0057] Example 4

[0058] The difference between this example and Example 1 is that the steel wire bundle consists of one helically ribbed steel wire at the center and six indented ribbed steel wires arranged around it. This structure is beneficial for the better bonding of the retarder filling layer to the sheath and the steel wire bundle, and can also improve the corrosion resistance of the retarder prestressed tendon.

[0059] Example 5

[0060] The difference between this example and Example 1 is that the steel wire bundle consists of one indented ribbed steel wire at the center and six helically ribbed steel wires arranged around it. This structure is beneficial for the better bonding of the retarder filling layer to the sheath and the steel wire bundle, and can also improve the corrosion resistance of the retarder prestressed tendon.

[0061] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0062] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A highly corrosion-resistant and slow-bonding prestressed tendon, characterized in that, Including: A steel wire bundle composed of seven steel wires, with the diameter of the steel wire bundle being 15.2 mm - 21.6 mm; A sheath sleeved outside the steel wire bundle; A slow-bonding agent filling layer formed by filling a slow-bonding agent between the steel wire bundle and the sheath, with the thickness of the slow-bonding agent filling layer being 1.0 mm - 1.25 mm.

2. The highly corrosion-resistant and slow-bonding prestressed tendon according to claim 1, wherein The steel wire bundle is composed of at least one of spiral rib steel wires, indented rib steel wires, and smooth round steel wires.

3. The highly corrosion-resistant and slow-bonding prestressed tendon according to claim 1, wherein The steel wire bundle is composed of a first steel wire located at the center and six second steel wires arranged around the first steel wire.

4. The highly corrosion-resistant and slow-bonding prestressed tendon according to claim 1, wherein, The thickness of the sheath is 0.8 mm - 1.9 mm.

5. The highly corrosion-resistant and slow-bonding prestressed tendon according to claim 1, wherein The material of the slow-bonding agent filling layer is an epoxy resin binder.

6. The highly corrosion-resistant and slow-bonding prestressed tendon according to claim 1, wherein The minimum stress corrosion value of the highly corrosion-resistant slow-bonding prestressed tendon is 2.0 h, and the median value is above 5.0 h.

7. The highly corrosion-resistant and slow-bonding prestressed tendon according to claim 1, wherein The steel wire bundle is made of wire rods. The chemical composition of the wire rods includes, by mass percentage, C 0.65 - 0.75%, Si 0.60 - 1.40%, Mn 0.20 - 0.80%, Cr 0.15 - 0.50%, Cu < 0.30%, Ni < 0.30%, Mo < 0.30%, V 0.02 - 0.05%, Nb 0.01 - 0.05%, S ≤ 0.008%, P ≤ 0.010%, N ≤ 0.0040%, O ≤ 0.0020%, and the rest is Fe and other inevitable impurities.

8. The highly corrosion-resistant and slow-bonding prestressed tendon according to claim 7, characterized in that The production method of the wire rods includes steelmaking, continuous casting, high-speed wire rolling, and post-rolling controlled cooling processes; Among them, in the high-speed wire rolling process, the billet obtained in the continuous casting process is heated and then successively subjected to rough rolling and finish rolling. The heating temperature is 1080 - 1150 °C, the starting rolling temperature of rough rolling is 950 - 1000 °C, the entry temperature of finish rolling is 840 - 880 °C, and the spinning temperature is 800 - 900 °C; The post-rolling controlled cooling process adopts on-line salt bath isothermal treatment and on-line aging treatment. In the on-line salt bath isothermal treatment, the salt bath temperature is 495 - 530 °C, and the salt bath time is 90 - 200 s; the on-line aging treatment is to place the wire rods after the on-line salt bath isothermal treatment in a heat preservation corridor, and the average cooling rate of the wire rods in the heat preservation corridor is not higher than 0.2 °C / s.

9. The highly corrosion-resistant and slow-bonding prestressed tendon according to claim 7, wherein, The wire rods are pickled, phosphated, drawn, stranded, and stabilized to obtain a steel wire bundle; Among them, the wire rods are pickled with a hydrochloric acid aqueous solution with a mass concentration of 15 - 20% for 7 - 10 min at a temperature of 35 - 42 °C; The drawing is carried out in 9 - 11 passes, the area reduction rate per pass is 23% - 25%, the drawing speed is not higher than 2 m / s, and the temperature rise per pass is not higher than 100 °C; The stranding tension is not lower than 80 kN, and the speed is not higher than 36 m / min; The stabilization temperature is 400 - 420 °C.

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