A manufacturing method of a UHPC prefabricated guardrail for expressway

Abstract

The application relates to a manufacturing method of a UHPC prefabricated guardrail for a highway, which comprises the following steps: weaving metal flat wires into a negative Poisson's ratio plane unit with a chiral lattice structure, and the rectangular arbitrary edge direction has at least three layers of the chiral lattice structure; performing a carbonization process treatment on the negative Poisson's ratio plane unit after being connected in series by using carbon fiber raw wires to form a sheet skeleton; magnetically polarizing micro straight steel fibers and then configuring UHPC slurry; pouring the UHPC slurry into a mold in which the sheet skeleton is placed, demolding after curing and solidification to obtain a prefabricated guardrail module. The sheet skeleton is composed of metal flat wires and carbon fibers, UHPC material is poured to form a prefabricated wave-shaped guardrail, the self weight is reduced, the energy absorption capacity and the impact resistance of the guardrail are improved, the density of the micro straight steel fibers in the magnetically controlled UHPC material and the exposed form of the UHPC solidification surface are changed to make the micro straight steel fibers have a hydrophobic surface, corrosion prevention effect is realized, and the service life of the guardrail is prolonged.

Description

Technical Field

[0001] This invention relates to the field of highway guardrail technology, and specifically to a method for manufacturing UHPC prefabricated guardrails for highways. Background Technology

[0002] With the increasing number of newly built highways each year, guardrails are a crucial link and important guarantee for highway operation and traffic safety. Highway traffic accidents have become a significant factor affecting the efficiency of highway operations. If the safety performance of crash barriers is inadequate, vehicles can easily overturn and fall off. Qualified guardrails should provide blocking, buffering, and guiding functions for out-of-control vehicles. However, currently, guardrails are mainly traditional steel or aluminum alloy guardrails. Traditional structures are very heavy, increasing the burden on the road. After long-term service, they age and have limited energy absorption under high-speed rigid collisions, making them prone to fracture and displacement, thus losing their guiding function. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a method for manufacturing UHPC prefabricated guardrails for highways. The method utilizes metal flat wires and carbon fiber to form a skeleton, and then casts UHPC material to form a prefabricated corrugated guardrail. This reduces the guardrail's weight while enhancing its energy absorption and impact resistance. Furthermore, by controlling the density of the micro-straight steel fibers within the magnetically controlled UHPC material and the exposed morphology of the UHPC cured surface, a hydrophobic surface is achieved, resulting in corrosion resistance and extending the guardrail's lifespan.

[0004] A method for manufacturing UHPC precast guardrails for highways includes the following steps:

[0005] S1: Weave flat metal wires with a thickness not exceeding 1 mm into negative Poisson's ratio planar units with chiral lattice structures, and the rectangles have at least three chiral lattice structures along any side direction;

[0006] S2: Use carbon fiber precursor to connect negative Poisson's ratio planar units in series and then process them with carbonization to form a thin sheet skeleton.

[0007] S3: Prepare UHPC slurry after magnetically polarizing the micro-straight steel fibers;

[0008] S4: Pour UHPC slurry into the mold where the thin-sheet skeleton is placed, and after curing, demold to obtain the prefabricated guardrail module.

[0009] Furthermore, the chiral lattice structure is any one of a three-ligament chiral lattice structure, a three-ligament chiral lattice structure, a four-ligament chiral lattice structure, or a four-ligament antichiral lattice structure.

[0010] Furthermore, the UHPC micro-straight steel fibers have a length of less than 0.1 mm, a diameter of less than 15 μm, and a dosage of 0.8 to 6 wt%.

[0011] Furthermore, in step S4, after the UHPC slurry is poured into the mold in which the thin sheet skeleton is placed, the polarized micro-straight steel fibers are magnetically attracted by a magnet parallel to the surface of the UHPC slurry, and some of the micro-straight steel fibers are vertically exposed on the surface of the UHPC slurry. After curing, a hydrophobic surface with a density of at least 300 fibers / square millimeter and a contact angle greater than 120° and less than 160° is obtained.

[0012] Furthermore, the UHPC micro-straight steel fiber content is 4.65%.

[0013] Furthermore, the short rectangular side of the negative Poisson's ratio planar unit determines the thickness of the sheet skeleton, and the thickness of the sheet skeleton is at least 5 mm.

[0014] Furthermore, in step S2, the carbon fiber precursor is connected in series with negative Poisson's ratio planar units for wave bending and carbonization, and then impregnated and coated with UHPC to form a prefabricated wave guardrail module.

[0015] Furthermore, in step S2, the carbon fiber precursor is connected in series with negative Poisson's ratio planar units, wound into a cylindrical shape and carbonized, and then impregnated and coated with UHPC to form a prefabricated hollow guardrail module.

[0016] Furthermore, the prefabricated hollow guardrail module is filled with lightweight foamed clay or Newtonian bodies.

[0017] Furthermore, the prefabricated guardrail module, the wave guardrail module, and the prefabricated hollow guardrail module are provided with reserved installation holes.

[0018] The technical advantages achieved by this invention are:

[0019] 1. This invention designs a UHPC prefabricated guardrail frame with chiral lattice structure and negative Poisson's ratio planar unit. The negative Poisson's ratio planar unit with chiral lattice structure absorbs impact energy and achieves better buffering and blocking function. The integrated curing of carbon fibers in series enhances the toughness of the guardrail and reduces the possibility of guardrail breakage, thus achieving better guiding function.

[0020] 2. This invention uses magnetic force to control the magnetized micro-straight steel fibers, forming a hydrophobic surface with a contact angle greater than 120° and less than 160°, which avoids corrosion from the natural environment after installation and effectively extends the life of the guardrail. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the negative Poisson's ratio square planar unit in Embodiment 1;

[0022] Figure 2 This is a schematic diagram of the sheet skeleton structure in Embodiment 1;

[0023] Figure 3 It is the hydrophobic surface of the prefabricated guardrail module;

[0024] Figure 4 This is a schematic diagram illustrating the hydrophobic principle of the rough surface formed by exposed micro-straight steel fibers.

[0025] Figure 5 This is a schematic diagram of a prefabricated wave guardrail module;

[0026] Figure 6 This is a schematic diagram of assembling prefabricated wave guardrail modules;

[0027] Figure 7 Flowchart of the manufacturing method of UHPC prefabricated guardrail for highways;

[0028] Figure 8 This is a left-side 3D view of the hollow guardrail module;

[0029] Figure 9 This is a left-side 3D view of the hollow guardrail module.

[0030] Figure label:

[0031] 1-Negative Poisson's ratio square planar unit, 2-Carbon fiber part, 3-Prefabricated wave guardrail module, 4-Stainless steel anti-blocking block, 5-Bolt, 6-Post, 7-Post cap. Detailed Implementation

[0032] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for manufacturing a UHPC prefabricated guardrail for highways according to the present invention:

[0033] Example 1

[0034] Metal flat wires with a width of 10mm and a thickness of 0.5mm are woven into a shape that resembles... Figure 1 The chiral lattice structure shown has a negative Poisson's ratio square planar unit 1 with four layers of chiral lattice structure along its edge, and the edge length is 1.5 cm. Fifty negative Poisson's ratio planar units are connected in series using Toray T700-12K carbon fiber precursor, and then carbonized to form a thin sheet skeleton with a thickness of 1.5 cm and a length of 50 cm. Figure 2 As shown in Table 1, micro-straight steel fibers with a length of less than 0.05 mm and a diameter of 5 μm are magnetically polarized and then UHPC slurry is prepared according to Table 1. The UHPC slurry is poured into a mold that holds the thin-sheet skeleton, and after curing, it is demolded to obtain a prefabricated guardrail module with a thickness of 3 cm.

[0035] Table 1 UHPC slurry ratio

[0036]

[0037] G represents polarized micro-straight steel fibers.

[0038] Example 2

[0039] Metal flat wires with a width of 10mm and a thickness of 0.5mm are woven into a shape that resembles... Figure 1 The chiral lattice structure shown has a negative Poisson's ratio square planar unit 1 with four layers of chiral lattice structure along its edge, and the edge length is 1.5 cm. Fifty negative Poisson's ratio planar units are connected in series using Toray T700-12K carbon fiber precursor, and then carbonized to form a thin sheet skeleton with a thickness of 1.5 cm and a length of 50 cm. Figure 2 As shown in the figure. Micro-straight steel fibers with a length less than 0.05 mm and a diameter of 5 μm were magnetically polarized, and UHPC slurry was prepared according to Table 1. The UHPC slurry was poured into a mold containing the thin-film skeleton. A 0.5T strong planar magnetic field was used to sweep the surface of the UHPC slurry across the future guardrail surface three times at a distance of 10 cm from the surface to be formed, at a speed of 15 m / s. After curing, the surface was demolded to obtain a hydrophobic surface (e.g., ...). Figure 3 The prefabricated guardrail module shown in Table 1 has a thickness of 3 cm and an exposed micro-straight steel fiber density of 120 to 220 fibers / mm², resulting in a hydrophobic surface with a contact angle of approximately 100° to 150°. Table 1 shows different micro-straight steel fiber ratios; the highest density (approximately 200 fibers / mm²) and a contact angle of approximately 150° are observed at a 4.65 wt% content. Increasing the content further does not improve hydrophobicity; instead, the contact angle decreases, reaching only 120° at a 6 wt% content.

[0040] Furthermore, carbon fiber precursors, by connecting negative Poisson's ratio planar units in series and undergoing wave bending and carbonization processes, followed by impregnation and coating with UHPC, can form a structure such as... Figure 5 3. Prefabricated wave guardrail module. Similarly, carbon fiber precursors are connected in series with negative Poisson's ratio planar units, wound into a cylindrical shape, and carbonized. Then, UHPC is impregnated, coated, cured, and demolded to obtain a prefabricated hollow guardrail module, such as... Figure 8 and 9 As shown.

[0041] Furthermore, lightweight filling materials such as foamed soil or Newtonian bodies are installed inside the prefabricated hollow guardrail modules to dissipate energy when the guardrail is subjected to impact.

[0042] In Examples 1 and 2, the planar or three-dimensional structure composed of the outer frame of the negative Poisson's ratio square planar unit serves as the main surface to withstand impact or shock. That is, the outer frame of the negative Poisson's ratio square planar unit receives the impact, and the frame compresses the chiral lattice inward to generate deformation and absorb energy.

[0043] like Figure 6As shown, prefabricated corrugated guardrail modules 3 are assembled end-to-end along the highway direction and fixed to stainless steel anti-collision blocks 4 by bolts 5 at the crests or troughs of the contour. The stainless steel anti-collision blocks 4 are fixed by through bolts on the posts 6. The posts 6 are installed inside the support sleeve of the fixing device, and post caps 7 are fixed to the top of the posts. The fixing device includes a mounting base, a support sleeve, and anchor bolts. The inner diameter of the support sleeve is larger than the outer diameter of the post 6. Double-ended bolts penetrate the diameter of the fitting part between the support sleeve and the post to prevent relative rotation, and fixing adhesive is injected into the gap. The support sleeve is welded to the mounting base, which is fixed to the roadbed by anchor bolts. Furthermore, the bolts at the crests or troughs of the contour of the prefabricated corrugated guardrail modules 3 can be connected to rigid springs before being fixed to the stainless steel anti-collision blocks, further improving the effect of buffering impact force.

[0044] against Figure 6 The guardrail structure was subjected to a collision test using an 18t large passenger bus at a speed of 80 km / h and an impact angle of 20°. No fracture occurred. After the collision, the guardrail's internal energy was 823 kJ. For a 3mm thick ferritic stainless steel corrugated beam guardrail, the internal energy was 427 kJ, nearly doubling the energy absorption capacity. The displacement of the prefabricated corrugated guardrail module 3 after the collision was 103.27 mm (far below the 500 mm limit required by current national standards for guardrails), while the displacement of the 3mm thick ferritic stainless steel corrugated beam guardrail after the collision was 270.34 mm.

[0045] The prefabricated corrugated guardrail modules obtained by the methods in Examples 1 and 2, along with the ferritic stainless steel corrugated beam guardrails, were placed in an environment with a temperature of 60°C and a humidity of 70% for four weeks and then subjected to a collision test. The prefabricated corrugated guardrail modules obtained by the methods in Examples 1 and 2 did not break. The displacement of the prefabricated corrugated guardrail module obtained by the method in Example 1 was 208.27 mm, the displacement of the prefabricated corrugated guardrail module obtained by the method in Example 2 was 117.36 mm, and the displacement of the ferritic stainless steel corrugated beam guardrail was 451.27 mm. It is evident that the hydrophobic treatment with magnetization prevents corrosion and aging, effectively extending the guardrail's lifespan and protective capability.

[0046] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Various changes that can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for manufacturing a UHPC precast guardrail for a highway, characterized in that, The method comprises the following steps: S1: weaving metal flat wire into a negative Poisson's ratio plane unit with a chiral lattice structure, and the rectangular arbitrary edge direction has at least three layers of chiral lattice structure; S2: using carbon fiber precursor to connect the negative Poisson's ratio plane unit in series and then performing carbonization process to form a sheet skeleton; S3: polarizing the micro straight steel fiber magnetically and then configuring UHPC slurry; S4: pouring the UHPC slurry into a mold in which the sheet skeleton is placed, and demolding after curing to obtain a prefabricated guardrail module; The chiral lattice structure is any one of a three-strand chiral lattice structure, a four-strand chiral lattice structure or a four-strand anti-chiral lattice structure; The length of the micro straight steel fiber is less than 0.1 mm, the diameter is less than 15 μm, and the content is 0.8-6 wt%; In step S4, after the UHPC slurry is poured into the mold in which the sheet skeleton is placed, the polarized micro straight steel fiber is magnetically attracted by a magnet parallel to the surface of the UHPC slurry, part of the micro straight steel fiber is exposed vertically on the surface of the UHPC slurry, and a hydrophobic surface with a density of at least 300 roots per square millimeter and a contact angle of greater than 120° and less than 160° is obtained after curing.

2. The method of manufacturing a UHPC precast guardrail for a highway according to claim 1, characterized in that, The content of the micro straight steel fiber is 4.65%.

3. The method for manufacturing a UHPC precast guardrail for a highway according to claim 1 or 2, characterized in that, The short side of the rectangular negative Poisson's ratio plane unit determines the thickness of the sheet skeleton, and the thickness of the sheet skeleton is at least 5 mm.

4. The method for manufacturing a UHPC precast guardrail for a highway according to claim 3, characterized in that, In step S2, the carbon fiber precursor connects the negative Poisson's ratio plane unit in series, performs wave bending and carbonization process, and then is infiltrated and coated by UHPC to form a prefabricated wave guardrail module.

5. The method of manufacturing a UHPC precast guardrail for a highway according to claim 3, wherein, In step S2, the carbon fiber precursor connects the negative Poisson's ratio plane unit in series, performs wave bending and carbonization process, and then is infiltrated and coated by UHPC to form a prefabricated wave guardrail module.

6. The method of manufacturing a UHPC precast guardrail for a highway according to claim 5, characterized in that, The prefabricated hollow guardrail module is provided with light filling material foamed earth or Newtonian body.

7. The method for manufacturing a UHPC precast guardrail for a highway according to claim 1 or 2, characterized in that, The prefabricated guardrail module is provided with a reserved mounting hole.

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