Anti-collision guardrail with ultra-high performance and anti-corrosion treatment and construction method of anti-collision guardrail

Abstract

The invention relates to the technical field of traffic infrastructures, and discloses an ultra-high performance anti-corrosion treatment anti-collision guardrail and a construction method thereof.The anti-collision guardrail comprises a prefabricated UHPC protection plate, a prefabricated ultra-high performance concrete (UHPC) protection plate, a prefabricated ultra-high performance concrete (UHPC) protection plate, a prefabricated ultra-high performance concrete (UHPC) protection plate and a prefabricated ultra-high performance concrete (UHPC) protection plate, the post-poured concrete is combined with the inner surface of the prefabricated UHPC protection plate; the protective plate and reinforcing steel bar connecting piece is pre-buried in the prefabricated UHPC protective plate, and a hole for a guardrail reinforcing steel bar framework to penetrate through is formed in the protective plate and reinforcing steel bar connecting piece; the protection plate bottom long round hole is formed in the bottom of the prefabricated UHPC protection plate; and the anti-collision guardrail steel member is arranged at the top of the post-poured concrete. Through dual positioning of the pre-embedded connecting piece and the long round hole, and combination of inner surface roughening and a fiber-free protection layer, the construction precision, the structural bonding strength and the durability are improved.

Description

Technical Field

[0001] This invention relates to the field of transportation infrastructure technology, specifically to a high-performance anti-corrosion crash barrier and its construction method. Background Technology

[0002] As a core component of traffic safety facilities, highway and bridge crash barriers serve in outdoor environments for extended periods. They must withstand the loads of accidental vehicle impacts and continuously resist the erosion of various corrosive media, including rainwater, freeze-thaw cycles, and de-icing salt in winter. To address these challenges, the structural reliability and material durability of crash barriers have become a focus of attention in the engineering field. Ultra-high performance concrete (UHPC), due to its extremely high strength, toughness, and excellent durability, is considered an ideal material for constructing the next generation of high-performance crash barriers.

[0003] Currently, the main technical solutions for applying UHPC to crash barriers include integral cast-in-place or precast assembly. One common approach is to use precast UHPC panels as a non-removable formwork, combining them with an internal steel reinforcement framework and subsequently poured conventional concrete to form a composite structure barrier. This solution aims to utilize UHPC as a protective layer on the oncoming surface to enhance the barrier's impact and corrosion resistance, while using conventional concrete as a filler to reduce costs.

[0004] While existing technologies have improved guardrail performance and construction convenience to some extent, several shortcomings remain. In construction methods combining precast panels with post-cast concrete, precise positioning and fixing of the precast panels is a significant technical challenge. Currently, manual leveling and fixing are typically achieved using external temporary supports, pads, or clamps. This process is not only time-consuming but also difficult to guarantee accuracy, especially under the lateral pressure of poured concrete, where temporary supports are prone to displacement, leading to uneven linearity and inconsistent protective layer thickness in the final guardrail. Furthermore, the interfacial bonding performance between the precast UHPC panels and the post-cast concrete directly affects the overall integrity of the composite structure. Because the inner surface of the precast UHPC panels is typically smooth during prefabrication, its bonding with the post-cast concrete relies mainly on chemical adhesion, with weak mechanical interlocking. Under vehicle impact loads or shear stress caused by drastic temperature changes, the smooth interface risks delamination, making it impossible to guarantee the coordinated stress distribution of the two layers. Moreover, although UHPC material itself has high density, steel fibers are typically incorporated internally to achieve its mechanical properties. During the pouring and vibration process, the distribution of steel fibers is random. Inevitably, some steel fibers will be exposed on the vehicle-facing surface of the guardrail or under an extremely thin protective layer. These exposed steel fibers will become the starting point for corrosion in humid and salt spray environments, resulting in rust spots and affecting the long-term aesthetics of the guardrail. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-performance anti-corrosion treated crash barrier and its construction method, solving the problems of low construction efficiency, poor installation accuracy, weak interface bonding, and insufficient long-term durability of existing composite crash barriers.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The first aspect of this invention provides a high-performance anti-corrosion treated crash barrier, the crash barrier comprising:

[0008] A prefabricated UHPC guard plate is installed on the front side of the crash barrier.

[0009] Post-cast concrete, which is bonded to the inner surface of the precast UHPC protective panel;

[0010] The precast UHPC guard plate and the steel bar connector are embedded in the precast UHPC guard plate, and the precast UHPC guard plate and the steel bar connector are provided with holes for the guardrail steel bar skeleton to pass through.

[0011] The prefabricated UHPC protective plate has an elongated hole at its bottom.

[0012] A steel crash barrier component is installed on top of the post-cast concrete.

[0013] Preferably, the front surface of the prefabricated UHPC guard plate is smooth and flat, and the inner surface of the prefabricated UHPC guard plate is roughened.

[0014] Preferably, the diameter of the holes opened on the prefabricated UHPC guard plate and the steel bar connector is 4-8 mm larger than the outer diameter of the longitudinal bars of the guardrail steel reinforcement skeleton.

[0015] Preferably, the elongated hole at the bottom of the prefabricated UHPC guardrail is used for the tie rod of the bottom cast-in-place guardrail steel formwork to pass through.

[0016] A second aspect of this invention provides a construction method for a high-performance anti-corrosion treated crash barrier, comprising the following steps:

[0017] S1. Provide prefabricated UHPC protective panels;

[0018] S2. Perform the first positioning of the prefabricated UHPC protective plate;

[0019] S3. Perform the second positioning of the prefabricated UHPC protective plate;

[0020] S4. Pour concrete after pouring the first concrete;

[0021] S5. Install steel components for crash barriers.

[0022] Preferably, step S1 includes:

[0023] A layer of fiber-free UHPC is sprayed into the template used to prefabricate the prefabricated UHPC liner, and then UHPC is poured immediately thereafter.

[0024] Preferably, step S2 includes the following steps:

[0025] The longitudinal reinforcing bars of the guardrail steel reinforcement skeleton pass through the holes in the precast UHPC guardrail plate and the steel reinforcement connector.

[0026] The first positioning is used to fix the height position of the precast UHPC guardrail and ensure the concrete thickness between the inner surface of the precast UHPC guardrail and the guardrail steel reinforcement skeleton.

[0027] Preferably, step S3 includes the following steps:

[0028] A steel formwork is installed behind the precast UHPC protective panel, and the bottom steel formwork tie rod of the steel formwork is passed through the elongated hole at the bottom of the precast UHPC protective panel.

[0029] The precast UHPC protective plate is tightly attached to the steel formwork using concrete spacers.

[0030] The second positioning is used to verify the position of the prefabricated UHPC liner and ensure its smoothness. The elongated hole at the bottom of the prefabricated UHPC liner allows for local adjustment of the longitudinal position of the liner to ensure that the longitudinal gap between adjacent liners is the same.

[0031] Preferably, step S4 includes the following steps:

[0032] A disposable protective paper is affixed to the front face of the prefabricated UHPC guard plate;

[0033] Post-cast concrete is poured between the precast UHPC protective plate and the steel formwork.

[0034] Preferably, step S5 includes the following steps:

[0035] Remove the steel formwork and tear off the disposable protective paper;

[0036] The oblong holes at the bottom of the precast UHPC liner were sealed with epoxy mortar.

[0037] The joint between the root of the precast UHPC protective panel and the top surface of the concrete pavement is sealed with sealant.

[0038] The steel components of the crash barrier are installed by pre-embedding anchor bolts on top of the post-cast concrete.

[0039] This invention provides a high-performance anti-corrosion treated crash barrier and its construction method. It has the following beneficial effects:

[0040] 1. This invention provides a stable benchmark for the initial positioning of the protective plate by pre-embedding the protective plate and the reinforcing steel connector within the precast UHPC protective plate. These connectors also act as internal spacers, effectively controlling the uniformity of the protective layer thickness of the subsequent concrete pour. Furthermore, the design of the elongated hole at the bottom of the protective plate allows for longitudinal fine-tuning, ensuring consistency in the joint width between adjacent plates, thereby improving overall linear smoothness and reducing construction errors and adjustment time.

[0041] 2. This invention roughens the inner surface of the precast UHPC guardrail, enhancing the mechanical interlocking force between it and the post-cast concrete. This roughened interface structure ensures reliable shear stress transfer under load, preventing interface delamination and enabling the precast UHPC layer and the post-cast concrete layer to work together to form an integral composite structure, thus improving the impact resistance and durability of the guardrail.

[0042] 3. This invention effectively isolates the internal steel fibers from external corrosive media by spraying a layer of fiber-free UHPC slurry onto the oncoming surface of the precast UHPC guardrail as a protective layer, fundamentally solving the problem of surface deterioration caused by steel fiber corrosion. Simultaneously, the use of disposable protective paper applied to the oncoming surface during construction avoids construction pollution and damage, ensuring the guardrail's freeze-thaw resistance, chloride salt corrosion resistance, and aesthetic appearance during long-term service. Attached Figure Description

[0043] Figure 1 This is a side view of the present invention;

[0044] Figure 2 This is a schematic elevation view of the prefabricated UHPC protective panel of the present invention;

[0045] Figure 3 This is a cross-sectional schematic diagram of the prefabricated UHPC protective plate of the present invention;

[0046] Figure 4 This is a schematic diagram of the longitudinal reinforcement of the guardrail according to the present invention;

[0047] Figure 5 This is a structural schematic diagram of the steel component of the anti-collision guardrail of the present invention.

[0048] The components include: 1. Precast UHPC guardrail; 2. Reinforcing bar connectors; 3. Oblong holes at the bottom of the guardrail; 4. Steel components of the crash barrier; 5. Longitudinal reinforcement of the guardrail; 6. Post-cast concrete; 7. Concrete pads; 8. Steel formwork; and 9. Tie rods for the steel formwork of the guardrail. Detailed Implementation

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Please see the appendix Figure 1 -Appendix Figure 5 One embodiment of the present invention provides a crash barrier with ultra-high performance anti-corrosion treatment. The crash barrier is a composite structure comprising:

[0051] Prefabricated UHPC protective panel 1;

[0052] Post-cast concrete 6;

[0053] 2. Connector between the protective plate and the reinforcing bar;

[0054] 3 oblong holes at the bottom of the guard plate;

[0055] 4. Steel components of the crash barrier.

[0056] The prefabricated UHPC guard plate 1 is installed on the front side of the crash barrier. The front side serves as an anti-corrosion surface to isolate corrosive media such as de-icing salt.

[0057] The prefabricated UHPC skid plate 1 has opposing front and inner surfaces. In one embodiment, the front surface is smooth and flat, which can be achieved by spraying a layer of fiber-free UHPC during prefabrication. The inner surface of the prefabricated UHPC skid plate 1 is roughened, for example, to allow fibers to protrude, in order to increase the contact area with the subsequently cast material.

[0058] The post-cast concrete 6 is poured and formed during construction and bonded to the inner surface of the precast UHPC cladding 1. The roughening treatment of the inner surface enhances the mechanical interlocking force between the precast UHPC cladding 1 and the post-cast concrete 6, making the two form a stable integral structure.

[0059] The guard plate and rebar connector 2 are embedded in the precast UHPC guard plate 1. Holes are provided on the guard plate and rebar connector 2 for the longitudinal bars 5 of the guardrail reinforcement skeleton to pass through.

[0060] In one specific embodiment, the diameter of the hole opened on the guardrail and the steel bar connector 2 is 4-8mm larger than the outer diameter of the guardrail longitudinal reinforcement 5. This design provides the necessary tolerance for construction and installation, facilitates the rapid installation of the guardrail longitudinal reinforcement 5, and still enables effective positioning of the precast UHPC guardrail 1 after installation.

[0061] An elongated hole 3 is formed at the bottom of the precast UHPC guardrail 1. The elongated hole 3 at the bottom of the guardrail is used for the tie rod 9 of the bottom cast-in-place guardrail steel formwork to pass through. The shape design of the elongated hole 3 also allows for local adjustment of the longitudinal position of the precast UHPC guardrail 1 in construction step S3.

[0062] The steel component 4 of the crash barrier is installed on top of the post-cast concrete 6. In one embodiment, the steel component 4 of the crash barrier is installed and fixed in construction step S5 by anchor bolts pre-embedded in the top of the post-cast concrete 6.

[0063] In the construction method of the present invention, step S1 involves the factory or on-site prefabrication of precast UHPC protective panels 1, which are used to provide protective units that meet the requirements of accuracy, strength and surface quality.

[0064] Step S1 may specifically include the following sub-steps:

[0065] S11. Mold Preparation and Assembly: Steel templates are selected as prefabrication molds to ensure the dimensional accuracy of the molded protective plates. The steel templates are designed with an adjustable structure. By adjusting the length of the straight sections at the top and bottom of the templates, the size of the mold cavity can be changed to produce prefabricated UHPC protective plates of different heights or lengths.

[0066] Before assembling the mold, clean the inner surface of the template and apply a release agent evenly. Pre-fix the core component used to form the elongated hole 3 at the bottom of the guard plate to the corresponding position at the bottom of the mold.

[0067] S12. Construction of the protective layer on the front side: In order to ensure the smoothness of the front side of the precast UHPC guard plate 1 and prevent the steel fiber from being exposed due to corrosion, a layer of fiber-free UHPC slurry is sprayed on the inner wall of the front side of the mold.

[0068] This fiber-free UHPC slurry contains no steel fibers and its thickness is controlled between 2 mm and 5 mm, with a preferred embodiment having a thickness of 3 mm. This process forms a smooth, flat, and dense pure cementitious matrix protective layer to block external corrosive media.

[0069] S13. Structural Layer Casting and Embedded Part Installation: After the fiber-free UHPC grout is sprayed in S12, the fiber-containing UHPC structural layer is cast immediately. To ensure a tight bond between the protective layer and the structural layer and to avoid cold joints or delamination, the casting operation is carried out immediately before the initial setting of the fiber-free layer. A wet-on-wet process is used to bond the two layers at the interface, and after curing, they form a whole.

[0070] During or before pouring, the guard plate and rebar connector 2 are positioned and pre-embedded into the mold at a predetermined depth. The position of the guard plate and rebar connector 2 needs to be accurately calculated based on the required protective layer thickness of the subsequent guardrail rebar skeleton.

[0071] If the holes on the steel bar connector 2 are prefabricated, the mandrel must be passed through during the pre-embedding process; if post-processing is used, the embedding depth and position of the connector 2 must be ensured to be accurate at this time.

[0072] S14. Inner Surface Roughening Treatment: When the UHPC grout has been poured but not yet fully hardened, the inner surface of the precast UHPC guard plate 1, i.e., the side facing away from the vehicle-facing side, is roughened manually or mechanically. Treatment methods include roughening, chiseling, or washing with a retarder to expose the aggregate. This process creates an uneven, rough texture on the inner surface to increase the mechanical interlocking force between the precast guard plate and the post-cast concrete 6 in subsequent step S4, preventing interface delamination.

[0073] S15. Curing, Demolding, and Post-processing: After the UHPC material reaches the demolding strength, remove the steel formwork. At this time, pull out the core located at the bottom, thus forming an elongated hole 3 at the bottom of the precast UHPC liner 1. If no holes are pre-drilled between the liner and the reinforcing bar connector 2, then at this stage, drill holes in the portion of the connector 2 exposed on the inner surface of the liner. The hole diameter must be strictly controlled to meet the tolerance requirements for subsequent reinforcing bar insertion.

[0074] After demolding and cleaning, immediately affix disposable protective paper to the smooth, oncoming surface of the precast UHPC guard plate 1. The disposable protective paper covers the entire oncoming surface to prevent mud contamination or mechanical scratches during subsequent transportation, hoisting, and cast-in-place concrete construction.

[0075] S16. Finished Product Storage and Transportation: The completed prefabricated UHPC protective panels 1 are stored and transported vertically. Foam boards or rubber pads are placed between adjacent panels as cushioning media to prevent the panels from colliding and causing damage to the edges. Vertical transportation conforms to the stress characteristics of the panels and can reduce the risk of cracking during transportation.

[0076] After the steel reinforcement skeleton of the guardrail is tied at the construction site, step S2 is carried out, which is the first positioning of the precast UHPC guardrail 1.

[0077] Step S2 may specifically include the following sub-steps:

[0078] S21: Hoist the prefabricated UHPC guardrail 1, which has been prepared in step S1 and has been affixed with disposable protective paper, into place. The operator aligns the prefabricated UHPC guardrail 1 with the already tied guardrail reinforcement skeleton, so that the longitudinal reinforcement 5 of the guardrail reinforcement skeleton passes through the holes on the guardrail and reinforcement connector 2 embedded in the prefabricated UHPC guardrail 1.

[0079] S22: The diameter of the hole opened on the guardrail and the steel bar connector 2 is 4-8mm larger than the outer diameter of the guardrail longitudinal reinforcement 5. This dimensional difference provides a construction tolerance, allowing the prefabricated UHPC guardrail 1 to be successfully installed even when there is a slight linear deviation or installation error in the guardrail longitudinal reinforcement 5, avoiding installation jamming caused by inaccurate hole positions.

[0080] S23: The embedding depth of the guard plate and the steel bar connector 2 in the precast UHPC guard plate 1 is preset. After the guardrail longitudinal reinforcement 5 passes through the hole, the structural body of the guard plate and the steel bar connector 2 forms a physical gap between the inner surface of the precast UHPC guard plate 1 and the guardrail longitudinal reinforcement 5.

[0081] S24: A pre-defined uniform gap is defined between the inner surface of the precast UHPC guardrail 1 and the guardrail steel reinforcement skeleton. This gap is the thickness of the protective layer of the post-cast concrete 6.

[0082] Simultaneously, the interlocking of the guardrail plate and the steel reinforcement connector 2 with the longitudinal reinforcement 5 of the guardrail suspends or fixes the precast UHPC guardrail plate 1 vertically at the design elevation. This is how step S2 completes the fixation of the precast UHPC guardrail plate 1 in the height direction and ensures the concrete thickness.

[0083] After the first positioning is completed in step S2, step S3 is performed, which is the second positioning of the prefabricated UHPC guard plate 1. This step is the second stage of the dual positioning system, used to accurately check the smoothness of the guard plate and control the gap between adjacent guard plates.

[0084] Step S3 may specifically include the following sub-steps:

[0085] S31: Install the steel formwork 8 on the back of the guardrail. The steel formwork 8 serves as the back formwork for the post-cast concrete 6. The steel formwork 8 and the inner surface of the precast UHPC guardrail 1 together define the pouring cavity of the post-cast concrete 6.

[0086] S32: The bottom cast-in-place guardrail steel formwork tie rod 9 of the steel formwork 8 passes through the elongated hole 3 at the bottom of the precast UHPC guardrail 1. The two ends of the bottom cast-in-place guardrail steel formwork tie rod 9 are fixed to the outside of the steel formwork 8 and the precast UHPC guardrail 1 respectively, or fixed by a specific anchor.

[0087] S33: A concrete pad 7 is fitted onto the bottom cast-in-place guardrail steel formwork tie rod 9 between the precast UHPC guardrail 1 and the steel formwork 8. The length of the concrete pad 7 is precisely designed to limit the minimum distance between the inner surface of the precast UHPC guardrail 1 and the inner surface of the steel formwork 8, i.e., the design thickness of the post-cast concrete 6.

[0088] S34: Tighten the bottom cast-in-place guardrail steel formwork tie rod 9 so that the precast UHPC guardrail 1 and the steel formwork 8 are pressed tightly against the concrete pad 7 from both sides under the action of the tie rod tension.

[0089] This step S34 completes the final verification and locking of the guard plate position, ensuring the smoothness of the guard plate and preventing the formwork from deforming or shifting due to lateral pressure when pouring concrete in S4.

[0090] S35: The structural feature of the elongated hole 3 at the bottom of the guardrail is used to achieve longitudinal adjustment. The longitudinal length of the elongated hole 3 is greater than the diameter of the bottom cast-in-place guardrail steel formwork tie rod 9. This design allows the precast UHPC guardrail 1 to have adjustable displacement in the longitudinal direction, i.e., the direction of guardrail extension.

[0091] S36: Before fully tightening the bottom cast-in-place guardrail steel formwork tie rod 9 in S34, the construction personnel use the longitudinal adjustable displacement provided by the elongated hole 3 at the bottom of the guard plate to make longitudinal fine adjustments to the precast UHPC guard plate 1, so as to correct and ensure that the longitudinal gap between adjacent guard plates is the same and uniform, and to ensure the quality of the joint.

[0092] After the second positioning is completed in step S3, and the positions of the precast UHPC protective plate 1 and the steel formwork 8 are checked and fixed correctly, step S4, namely, pouring the post-concrete 6, is carried out.

[0093] Step S4 may specifically include the following sub-steps:

[0094] S41: Before the pouring operation of S43 begins, attach disposable protective paper to the oncoming side of the precast UHPC guard plate 1.

[0095] S42: The application of disposable protective paper must ensure complete coverage of the front face of the precast UHPC guard plate 1, especially the edges near the joints and top surface, to prevent concrete slurry from splashing or overflowing during the pouring of post-concrete 6 in step S43, which could contaminate or scratch the smooth surface of the front face.

[0096] S43: Pour post-cast concrete 6 between the precast UHPC protective plate 1 and the steel formwork 8. The post-cast concrete 6 is poured into the cavity enclosed by the steel formwork 8 and the precast UHPC protective plate 1 through a concrete pump or chute.

[0097] S44: During the pouring process, the concrete is poured in layers and thoroughly vibrated using an immersion vibrator. The vibration operation ensures that the concrete is densely packed, completely encapsulates the guardrail reinforcement skeleton, and tightly bonds with the rough inner surface formed in S14 of the precast UHPC guardrail 1, eliminating internal voids and air pockets to ensure the composite interface bonding strength between the post-poured concrete 6 and the precast UHPC guardrail 1.

[0098] S45: After pouring to the design elevation, the top surface of the post-poured concrete 6 is finished and smoothed. After finishing, the exposed concrete surface is covered, for example, by using plastic film or watering to prevent moisture from evaporating too quickly.

[0099] After the post-cast concrete 6 in step S4 reaches the predetermined demolding strength, step S5 is executed. Step S5 includes demolding of the guardrail, finishing, and installation of the top components.

[0100] Step S5 may specifically include the following sub-steps:

[0101] S51: Remove the steel formwork 8 located behind the guardrail. At the same time, remove the disposable protective paper pasted on the front face of the precast UHPC guardrail 1.

[0102] S52: The removal of the disposable protective paper exposes the front face of the precast UHPC slab 1, which had been kept smooth during concrete pouring due to the cover of the disposable protective paper.

[0103] S53: Use epoxy mortar to seal the oblong hole 3 at the bottom of the protective plate.

[0104] S54: The oblong hole 3 at the bottom of the guardrail is for the tie rod 9 of the bottom cast-in-place guardrail steel formwork to pass through in step S3. After the tie rod is removed, the hole is sealed with epoxy mortar. The high adhesion and impermeability of the epoxy mortar are used to permanently seal the channel, preventing external moisture or corrosive media from penetrating into the post-cast concrete 6 or contacting the guardrail steel reinforcement skeleton through the hole.

[0105] S55: Use sealant to seal the joint between the base of the precast UHPC protective panel 1 and the top surface of the concrete pavement.

[0106] S56: Sealing adhesive is applied to the junction of the precast UHPC guardrail 1 and the road or bridge deck pavement to form a flexible waterproof barrier. This sealing treatment prevents surface runoff, rainwater, or de-icing salt solution from seeping into the bottom structure of the guardrail along the joint, while also accommodating minor deformations between different materials.

[0107] S57: Install the anti-collision guardrail steel component 4 on top of the post-cast concrete 6.

[0108] S58: The steel component 4 of the crash barrier is fixed by anchor bolts pre-embedded in the top of the post-poured concrete 6. The anchor bolts were pre-embedded during the concrete pouring in step S4. During installation, the base holes of the steel component 4 of the crash barrier are aligned with the anchor bolts, and tightened with nuts and washers, thereby rigidly connecting the steel component 4 of the crash barrier to the post-poured concrete 6.

[0109] The above are embodiments of the present invention.

[0110] Comparative Example 1:

[0111] Compared to the previous embodiment, the difference lies in that the entire crash barrier is cast in one piece using conventional post-cast concrete 6, without the installation of precast UHPC protective panels 1. With this method of construction, the front face of the barrier is directly exposed to the external environment, resulting in poor corrosion resistance, freeze-thaw resistance, and abrasion resistance, leading to a short service life.

[0112] Comparative Example 2:

[0113] The difference from the previous embodiment is that the inner surface of the precast UHPC guard plate 1 produced in step S1 is smooth and has not undergone the roughening treatment in S14. This results in a significant lack of mechanical interlocking force between the precast UHPC guard plate 1 and the post-cast concrete 6. Under vehicle impact loads or long-term temperature differences, there is a risk of delamination at the interface between the two, affecting the overall structural integrity.

[0114] Comparative Example 3:

[0115] The difference compared to the previous embodiment is that the prefabricated UHPC guardrail 1 produced in step S1 is entirely cast using fiber-containing UHPC, and its front face is not sprayed with the fiber-free UHPC slurry of S12 as a protective layer. This inevitably results in exposed steel fibers on the front face of the guardrail. In a humid environment, the exposed steel fibers will rust and form rust spots, affecting the aesthetics of the guardrail.

[0116] Comparative Example 4:

[0117] The difference from the previous embodiment is that the precast UHPC protective plate 1 does not have pre-embedded protective plate and steel bar connectors 2. Its initial positioning and control of the protective layer thickness rely on external temporary supports and spacers. This method is difficult to guarantee installation accuracy, has low construction efficiency, and the spacers are prone to displacement during concrete pouring, resulting in uneven protective layer thickness.

[0118] Comparative Example 5:

[0119] Compared to the previous embodiment, the difference lies in that the oblong hole 3 at the bottom of the precast UHPC guardrail 1 is replaced with a circular hole that matches the diameter of the tie rod 9 of the bottom cast-in-place guardrail steel formwork. This causes the precast UHPC guardrail 1 to lose its ability to make longitudinal fine adjustments during the second positioning in step S3, making it difficult to control the uniformity of the joint width between adjacent guardrails, thus affecting the final linear smoothness and appearance quality.

[0120] Experimental Example 1:

[0121] Experimental steps:

[0122] Construction process and accuracy assessment:

[0123] Applicable to: Examples, Comparative Example 4, Comparative Example 5.

[0124] Evaluation indicators: positioning time of a single precast UHPC panel, uniformity of the thickness of the post-cast concrete protective layer, and uniformity of the joint width between adjacent panels.

[0125] Operating steps:

[0126] A three-person construction team from the same group installed a section of guardrail consisting of three prefabricated UHPC guardrail panels using the methods of Example 4, Comparative Example 5, and Comparative Example 5, respectively.

[0127] Use a stopwatch to record the total time consumed from the start of the guard plate hoisting to the completion of the first and second positioning.

[0128] After the second positioning is completed and before pouring concrete, 10 measurement points are randomly selected using depth calipers to measure the distance between the inner surface of the precast UHPC guardrail and the guardrail steel reinforcement skeleton, and the range of the protective layer thickness (maximum value - minimum value) is calculated.

[0129] Similarly, after positioning, use a feeler gauge to measure the width of the two vertical seams at the top, middle, and bottom positions, and calculate the range of seam width.

[0130] Structural integration performance evaluation:

[0131] Applicable to: Examples and Comparative Example 2.

[0132] Evaluation index: interfacial bonding performance between precast UHPC protective panels and post-cast concrete 6.

[0133] Operating steps:

[0134] From the completed guardrail specimens of Example 1 and Comparative Example 2, cut out test blocks with a guardrail thickness of 400mm x 400mm, ensuring that the mating surface is located in the middle of the test block.

[0135] The specimen was placed on a compression testing machine for a push-out shear test. The loading head was applied to one side of the post-cast concrete 6, with the support point located on one side of the precast UHPC retaining plate. The load was applied until interface failure or overall specimen failure occurred.

[0136] The recording interface begins to show the ultimate load at the point of relative slippage or peeling, and the final failure mode is observed and recorded.

[0137] Durability and surface quality assessment:

[0138] Applicable to: Examples, Comparative Example 1, Comparative Example 3.

[0139] Evaluation indicators: corrosion resistance and appearance changes of the guardrail's front side.

[0140] Operating steps:

[0141] Surface specimens measuring 150mm x 150mm were cut from the oncoming side of the guardrails of the three specimens.

[0142] The sample was placed in a salt spray test chamber and subjected to a neutral salt spray test for 1000 consecutive hours in accordance with the standard GB / T10125-2012 "Artificial Atmosphere Corrosion Test - Salt Spray Test".

[0143] After the test, remove the samples, rinse them with clean water, and dry them. Visually observe and record the corrosion condition of each sample surface, such as rust spots, peeling, and efflorescence.

[0144] The test results are shown in Table 1:

[0145] Table 1: Performance Comparison Test Data Record of Composite Crash Barriers

[0146]

[0147] From Table 1, we can obtain:

[0148] In terms of construction efficiency and accuracy, the positioning time in the embodiment was 23.5 minutes, while that in Comparative Example 4 was 78.2 minutes. This difference lies in the fact that the embodiment uses a pre-embedded protective plate and steel bar connector 2, which provides a positioning reference and avoids the process of repeated adjustments relying on temporary shims as in Comparative Example 4.

[0149] Regarding the control of the protective layer thickness, the thickness range of the embodiment is 2.8 mm, while that of the comparative example 4 is 14.3 mm. The data shows that the connector 2, as an internal spacer, serves to ensure the uniformity of the protective layer of the post-poured concrete 6.

[0150] Regarding seam control, the seam width difference in this embodiment is 1.1 mm, while in Comparative Example 5 it is 5.8 mm. This result indicates that the longitudinal fine-tuning function of the elongated hole 3 at the bottom of the protective plate allows for control of the plate spacing during the second positioning, while the circular hole structure of Comparative Example 5 does not possess this function.

[0151] Regarding structural bonding performance, the inner surface of the prefabricated UHPC cladding was roughened to improve the overall integrity of the composite structure. The interface ultimate load of this embodiment was 215.4 kN, with the failure mode being substrate failure. In contrast, Comparative Example 2, with a smooth inner surface, had an interface ultimate load of 92.8 kN and a failure mode of interfacial delamination.

[0152] This result indicates that the rough inner surface formed in step S14 provides mechanical interlocking force, enabling the precast UHPC layer and the post-cast concrete 6 layers to work together under load, thus preventing delamination under load.

[0153] In terms of durability, after 1000 hours of salt spray testing, the surface of the sample in the example was intact; the surface of ordinary concrete in Comparative Example 1 deteriorated; and the surface of Comparative Example 3 developed rust spots due to exposed steel fibers.

[0154] This demonstrates that the fiber-free UHPC slurry protective layer used in the embodiments can block the intrusion of corrosive media and the corrosion of steel fibers, thus playing a role in maintaining the appearance and long-term durability of the guardrail.

[0155] Based on the comprehensive test results, the design of the connectors between the guardrail and the reinforcing bars, as well as the elongated hole at the bottom of the guardrail, improved construction efficiency and installation accuracy. The roughening treatment of the inner surface of the UHPC guardrail ensured the bonding strength between the precast and post-cast parts and the overall structural integrity. The fiber-free protective layer on the vehicle-facing side enhanced the long-term environmental durability of the guardrail.

[0156] Experimental Example 2:

[0157] Experimental steps:

[0158] Efficiency and accuracy assessment of the construction process:

[0159] Test subjects: Example 1, Comparative Example 4, Comparative Example 5.

[0160] Evaluation indicators: time spent on positioning and verification of a single precast UHPC panel, uniformity of the thickness of the 6 protective layers of the post-cast concrete, and uniformity of the joint width between adjacent panels.

[0161] Operating steps:

[0162] Each of the three construction teams installed a section of guardrail consisting of three prefabricated UHPC guardrail panels (or equivalent units) according to their respective technical plans.

[0163] Use a stopwatch to record the total time consumed from the moment the protective panels are hoisted into place until the positioning of all protective panels (including the first and second positioning checks and fixation) is completed.

[0164] After the second positioning is completed and before pouring concrete, use a laser rangefinder or calipers to randomly select 15 points within the guardrail section to measure the gap between the inner surface of the precast UHPC guardrail panel and the guardrail steel reinforcement skeleton (guardrail longitudinal reinforcement 5). Record the measurement results and calculate the difference between the maximum and minimum values ​​of the gap (range) to characterize the uniformity of the protective layer thickness.

[0165] After completing all positioning, use vernier calipers to measure the width of the two vertical joints within the guardrail section at three points (top, middle, and bottom, for a total of six points). Record the measurement results and calculate the range of this width to characterize the uniformity of the joints.

[0166] Evaluation of the bonding performance between precast UHPC panels and post-cast concrete at six interfaces:

[0167] Test subjects: Example 1 and Comparative Example 2.

[0168] Evaluation index: Shear strength of the composite interface between the precast UHPC retaining panel and the post-cast concrete.

[0169] Operating steps:

[0170] Composite test blocks with a thickness of 300mm × 300mm were cut from the fully cured guardrail specimens of Example 1 and Comparative Example 2. Each test block was ensured to contain a complete precast UHPC cladding layer, a composite interface, and six layers of post-cast concrete.

[0171] The composite specimen was placed on a universal testing machine, and the push-out shear test method was used. The loading head was applied to the sixth layer of post-cast concrete, with the bottom support located on the precast UHPC retaining plate layer. Axial pressure was applied to generate shear force.

[0172] Record the load value at which relative slippage begins at the interface (end of the elastic stage) and the ultimate load that leads to complete interface delamination or overall specimen failure. Simultaneously observe and record the final failure mode, whether it is interface delamination failure or substrate failure.

[0173] Corrosion resistance and surface quality assessment of the guardrail's oncoming surface:

[0174] Test subjects: Example 1, Comparative Example 3.

[0175] Evaluation indicators: freeze-thaw resistance, impermeability, and surface rust condition of the guardrail's front side.

[0176] Operating steps:

[0177] Surface specimens with a thickness of 150mm × 150mm were cut from the oncoming side of the guardrails of the three specimens.

[0178] The samples were immersed in a saturated sodium chloride solution for 24 hours and then subjected to a rapid freeze-thaw cycle test. Each cycle consisted of freezing at -18°C for 4 hours and thawing at 20°C for 4 hours. A total of 300 freeze-thaw cycles were performed.

[0179] After completing the freeze-thaw cycle, the sample was immersed in a water tank containing a 10% sodium chloride solution for 30 days to simulate a de-icing salt environment.

[0180] After the test, the samples were removed, rinsed with clean water, and dried. The macroscopic deterioration of each sample surface was visually inspected, including but not limited to cracking, peeling, rust spots, and efflorescence. For Comparative Example 3, the corrosion development at the exposed steel fiber locations was specifically examined.

[0181] The test results are shown in Table 2:

[0182] Table 2: Comparative Test Data of Composite Crash Barrier Performance

[0183]

[0184] From Table 2, we can obtain:

[0185] Regarding construction efficiency and installation accuracy, a comparison of the data from the embodiment with Comparative Examples 4 and 5 shows that the total time for positioning and verification in the embodiment is 24.8 minutes, lower than the 76.5 minutes in Comparative Example 4. This is attributed to the fact that the pre-embedded guard plate and rebar connector 2 in the embodiment provide a precise positioning benchmark, avoiding repeated adjustments relying on temporary supports and pads as in Comparative Example 4. The protective layer thickness variation in the embodiment is 2.5 mm, better than the 13.8 mm in Comparative Example 4. This confirms that the guard plate and rebar connector 2, acting as built-in spacers, control the spacing between the guardrail rebar skeleton and the precast UHPC guard plate, ensuring uniform protective layer thickness of the post-cast concrete 6. The joint width variation in the embodiment is 1.3 mm, better than the 6.2 mm in Comparative Example 5. This indicates that the design of the elongated hole 3 at the bottom of the guard plate in this invention provides the capability for longitudinal fine-tuning of the guard plate, ensuring precise consistency in the gaps between adjacent guard plates and guaranteeing a smooth guardrail line. The circular hole structure in Comparative Example 5 lacks this adjustment capability, resulting in reduced accuracy.

[0186] Regarding the interfacial bonding performance of the composite structure, the data comparison between the embodiment and Comparative Example 2 verified the effect of the roughening treatment (S14) on the inner surface of the precast UHPC cladding. The interface push-out shear limit load of the embodiment was 208.5 kN, and the failure mode was the overall failure of the UHPC substrate or the post-cast concrete 6, without interfacial delamination. This indicates that the rough texture formed in step S14 enhanced the mechanical interlocking force with the post-cast concrete 6, enabling reliable shear stress transfer at the composite interface and ensuring the collaborative work of the two material layers. In Comparative Example 2, the UHPC cladding with a smooth inner surface had an interface push-out shear limit load of only 89.2 kN, and the failure mode was typical interfacial delamination. This comparative result quantifies the effect of the roughening treatment on improving the interfacial bonding strength.

[0187] Regarding the durability of the guardrail and the quality of the oncoming surface, the data comparison between the embodiment and Comparative Examples 1 and 3 highlights the improved protective performance of the present invention. After freeze-thaw and chloride salt corrosion tests, the oncoming surface of the embodiment remained intact, without cracks, peeling, or rust spots. This is attributed to the impermeability and durability of the prefabricated UHPC guardrail 1, and the fiber-free UHPC protective layer sprayed in step S12. This protective layer isolates the steel fibers from external corrosive media, preventing steel fiber corrosion. The monolithic cast-in-place ordinary concrete guardrail of Comparative Example 1 exhibited large-area efflorescence, localized peeling, and even exposed steel reinforcement corrosion, indicating insufficient durability. The UHPC guardrail of Comparative Example 3, lacking a fiber-free protective layer on the oncoming surface, showed brown dotted rust spots, confirming the impact of exposed steel fibers in a corrosive environment on the appearance and performance of the guardrail.

[0188] This invention solves the problems of low construction efficiency, difficulty in precision control, poor durability, and easy deterioration of appearance associated with traditional guardrails through integrated construction methods and structural design. Experimental data demonstrates these technical advantages, proving the engineering application value of this invention in the field of transportation infrastructure construction.

[0189] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-performance anti-corrosion treated crash barrier, characterized in that, The crash barrier includes: A prefabricated UHPC guard plate (1) is provided on the front side of the crash barrier; Post-cast concrete (6) is bonded to the inner surface of the precast UHPC protective plate (1); The precast UHPC guard plate (1) and the steel bar connector (2) are embedded in the precast UHPC guard plate (1), and the precast UHPC guard plate (1) and the steel bar connector (2) are provided with holes for the guardrail steel bar skeleton to pass through. The oblong hole (3) at the bottom of the prefabricated UHPC protective plate (1) is located at the bottom of the prefabricated UHPC protective plate (1). The anti-collision guardrail steel component (4) is installed on top of the post-cast concrete (6).

2. The anti-collision guardrail with ultra-high performance anti-corrosion treatment according to claim 1, characterized in that, The front surface of the prefabricated UHPC guard plate (1) is smooth and flat, and the inner surface of the prefabricated UHPC guard plate (1) is roughened.

3. The anti-collision guardrail with ultra-high performance anti-corrosion treatment according to claim 1, characterized in that, The diameter of the holes opened on the prefabricated UHPC guard plate (1) and the steel bar connector (2) is 4-8 mm larger than the outer diameter of the longitudinal reinforcement (5) of the guardrail steel bar skeleton.

4. The anti-collision guardrail with ultra-high performance anti-corrosion treatment according to claim 1, characterized in that, The prefabricated UHPC guard plate (1) has an elongated hole (3) at the bottom for the bottom cast-in-place guardrail steel formwork tie rod (9) to pass through.

5. A construction method for a high-performance anti-corrosion treated crash barrier, characterized in that, The anti-collision guardrail using the ultra-high performance anti-corrosion treatment according to any one of claims 1-4 includes the following steps: S1. Provide prefabricated UHPC protective panels (1); S2. Perform the first positioning of the prefabricated UHPC protective plate (1); S3. Perform the second positioning of the prefabricated UHPC protective plate (1); S4. Pouring post-concrete (6). S5. Install steel components for crash barriers (4).

6. The construction method of a high-performance anti-corrosion treated crash barrier according to claim 5, characterized in that, Step S1 includes: A layer of fiber-free UHPC is sprayed into the template used to prefabricate the prefabricated UHPC liner (1), and then UHPC is immediately poured.

7. The construction method of a high-performance anti-corrosion treated crash barrier according to claim 6, characterized in that, S2 includes the following steps: The longitudinal reinforcement bars (5) of the guardrail steel reinforcement skeleton pass through the holes in the precast UHPC guardrail plate (1) and the steel reinforcement connector (2). The first positioning is used to fix the height position of the precast UHPC guard plate (1) and ensure the concrete thickness between the inner surface of the precast UHPC guard plate (1) and the guardrail steel reinforcement skeleton.

8. The construction method of a high-performance anti-corrosion treated crash barrier according to claim 7, characterized in that, S3 includes the following steps: A steel template is installed behind the precast UHPC guard plate (1), and the bottom cast-in-place guardrail steel template tie rod of the steel template passes through the elongated hole (3) at the bottom of the precast UHPC guard plate (1). The precast UHPC protective plate (1) is attached to the steel formwork (8) using concrete pads (7); The second positioning is used to verify the position of the prefabricated UHPC guard plate (1) and ensure the smoothness of the guard plate. The elongated hole (3) at the bottom of the prefabricated UHPC guard plate (1) allows for local adjustment of the longitudinal position of the guard plate to ensure that the longitudinal gap between adjacent guard plates is the same.

9. The construction method of a high-performance anti-corrosion treated crash barrier according to claim 8, characterized in that, S4 includes the following steps: A disposable protective paper is pasted on the front side of the prefabricated UHPC guard plate (1); Post-cast concrete (6) is poured between the precast UHPC protective plate (1) and the steel formwork (8).

10. The construction method of a high-performance anti-corrosion treated crash barrier according to claim 9, characterized in that, S5 includes the following steps: Remove the steel formwork (8) and tear off the disposable protective paper; Epoxy mortar was used to seal the elongated hole (3) at the bottom of the precast UHPC protective plate (1); The joint between the root of the precast UHPC protective panel (1) and the top surface of the concrete pavement is sealed with sealant. The anti-collision guardrail steel component (4) is installed by pre-embedding anchor bolts on the top of the post-cast concrete (6).

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