A temporary expansion joint structure
By placing foam boards at the centerline position in the expansion joint structure, combined with bamboo plywood and a filling layer, a rigid integral structure is formed, which solves the problem of edge chipping at the junction of new and old concrete and improves the flatness and stability of the bridge.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG COMM CONSTR GRP CO LTD
- Filing Date
- 2025-08-21
- Publication Date
- 2026-07-17
AI Technical Summary
In existing technologies, the unevenness at the junction of new and old concrete in temporary expansion joint structures leads to a nibbling phenomenon at the ends of bridge deck pavement (nibbling phenomenon caused by repeated impact effects of vehicle loads, and impact effects of vehicle loads). The technical problem that cannot be effectively solved is how to improve the technology.
In the expansion joint structure, the foam board is vertically placed at the center line position, combined with bamboo plywood, filling layer and pouring layer to form a rigid integral structure, avoiding the flexibility difference at the junction of new and old concrete. Through the design of the filling layer and pouring layer, a smooth transition is formed to eliminate the impact effect.
It effectively prevents edge chipping at the ends of the bridge deck pavement, reduces concrete edge damage, improves the smoothness of construction and the stability of the structure, and enhances the durability of the bridge.
Smart Images
Figure CN224514046U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of road and bridge construction technology, and in particular to a temporary expansion joint structure. Background Technology
[0002] Expansion joints are specialized structures in bridges or highways designed to accommodate structural deformation. They are primarily located between beam ends, at the connection between beam ends and abutments, or at hinged joints. Their core functions include: mitigating displacement caused by thermal expansion and contraction due to temperature changes, concrete shrinkage and creep, and load deflection; preventing rainwater, silt, and other foreign matter from seeping into the structure; and protecting critical components such as piers and supports from corrosion.
[0003] In the existing technology, there is a temporary expansion joint design scheme, referring to... Figure 1 This scheme has been used in highway and bridge construction. Its characteristic is that 8cm thick foam boards are placed on both sides of the fill layer and concrete. Although this scheme is relatively convenient to lay, the applicant found obvious defects in actual application: the foam boards placed on both sides are prone to causing "edge erosion" in the end bridge deck pavement.
[0004] Analysis revealed that the primary cause of the problem was that the interface between the newly poured concrete and the existing concrete was located precisely where the foam board was situated. As a flexible partition, the foam board exhibits differences in the hardening, shrinkage, and stress distribution of the concrete structures on either side, making it difficult to achieve a smooth transition at the interface. When vehicle loads repeatedly pass over this uneven area, a significant impact effect is generated, ultimately causing edge chipping and damage to the concrete. Utility Model Content
[0005] The technical problem this utility model aims to solve is how to improve the structure of temporary expansion joints to effectively address the problem of edge chipping and damage at the ends of bridge deck pavement caused by unevenness at the junction of new and old concrete.
[0006] To achieve the above objectives, according to one aspect of the utility model, a temporary expansion joint structure is provided, which is disposed between two adjacent piers. The piers are provided with pre-embedded reinforcing bars. The temporary expansion joint structure includes a bamboo plywood, a foam board, a filling layer, and a first pouring layer. The bamboo plywood is filled above the gap between the two adjacent piers. The foam board is vertically disposed on the bamboo plywood and located at the center line of the expansion joint. The filling layer covers the bamboo plywood and is located on both sides of the foam board, at least partially covering the height of the foam board. The first pouring layer covers the filling layer and is located on both sides of the foam board, with its upper surface flush with the upper surface of the foam board.
[0007] As a preferred embodiment of the above technical solution, a second pouring layer is provided between the two sides of the filling layer and the pier, and the first pouring layer and the second pouring layer are integrally formed.
[0008] As a preferred embodiment of the above technical solution, the filling layer is an EPS block layer made of geotextile foam.
[0009] As a preferred embodiment of the above technical solution, a first geotextile is provided between the filling layer and the first pouring layer.
[0010] As a preferred embodiment of the above technical solution, the filling layer is a graded crushed stone filling layer made of graded crushed stone.
[0011] As a preferred embodiment of the above technical solution, a second geotextile is provided between the lower end of the filling layer and the pier and the bamboo plywood.
[0012] As a preferred embodiment of the above technical solution, side templates are also provided on both sides of the foam board, and the side templates are located at least between the foam board and the first casting layer.
[0013] As a preferred embodiment of the above technical solution, the EPS block layer is provided with a plurality of through holes for the pre-embedded reinforcing bars to pass through; or, the EPS block layer is composed of a plurality of EPS blocks spliced together, and the pre-embedded reinforcing bars are located in the gap between adjacent EPS blocks.
[0014] As a preferred embodiment of the above technical solution, the length of the bamboo plywood extending beyond the outer edge of the gap between the two ends of the platform is not less than 10 centimeters.
[0015] As a preferred embodiment of the above technical solution, the bamboo plywood floor is provided with several supporting steel bars, and the spacing between adjacent supporting steel bars is no more than 30cm.
[0016] In summary, this utility model has the following advantages:
[0017] 1. The core improvement of this utility model lies in vertically positioning the foam board at the center line of the expansion joint. This design moves the interface between the old and new concrete away from the flexible barrier of the foam board, shifting it to the more structurally stable filling layer and first pouring layer area. Simultaneously, the centrally positioned foam board facilitates stress concentration and release in the middle of the joint. The combination of these two points significantly reduces the impact of vehicle loads on the interface between the old and new concrete, effectively preventing edge chipping at the bridge deck pavement ends and greatly alleviating the problem of concrete edge damage.
[0018] 2. The foam board is located on the center line, which facilitates positioning and fixing during construction, making it easier to control the overall flatness of the expansion joint area.
[0019] 3. The first and second pouring layers are integrally formed, together constituting a rigid concrete monolith. This rigid structure not only effectively protects the old concrete portion on the pier below from damage, but its own integrity and rigidity further eliminate the problem of abrupt stiffness changes between the old and new concrete, fundamentally suppressing the occurrence of edge chipping.
[0020] Further or other beneficial effects will be discussed in the embodiments. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the existing technical solution structure;
[0022] Figure 2 This is a schematic diagram of the structure of Embodiment 1 of the present utility model;
[0023] Figure 3 This is a schematic diagram of the structure of Embodiment 2 of this utility model;
[0024] Figure 4 This is a schematic diagram of the EPS block layer structure;
[0025] Figure 5 This is a schematic diagram of the first type of EPS block structure;
[0026] Figure 6 This is a schematic diagram of the second type of EPS block structure;
[0027] Figure 7 This is a schematic diagram of the third type of EPS block structure;
[0028] Among them, 1-bamboo plywood, 2-foam board, 31-EPS block layer, 311-through hole, 312-EPS block, 32-graded crushed stone filling layer, 41-first pouring layer, 42-second pouring layer, 51-first geotextile, 52-second geotextile, 6-side formwork, 7-pier, 71-embedded steel bar, a-thin foam board. Detailed Implementation
[0029] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the construction shown in the accompanying drawings. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.
[0030] The present invention will be further explained below with reference to the embodiments:
[0031] Example 1:
[0032] A temporary expansion joint structure, referring to Figure 2 The temporary expansion joint is set between two adjacent piers 7, and the piers 7 are provided with pre-embedded steel bars 71. The piers 7 include beams and abutments. The temporary expansion joint structure includes bamboo plywood 1, foam board 2, filling layer and first pouring layer 41.
[0033] Bamboo plywood 1 is laid horizontally directly above the gap between two adjacent piers 7, serving as the basic support surface for the entire temporary joint. To ensure sufficient support area and stability, both ends of bamboo plywood 1 include outer edges extending beyond the gap between the piers 7, with the length of each extended outer edge preferably not less than 10 cm. Furthermore, to effectively resist the pressure of poured concrete and prevent downward deflection of bamboo plywood 1, multiple supporting steel bars are horizontally installed below bamboo plywood 1 at intervals of not less than 30 cm. This design significantly enhances the rigidity and uniformity of the bottom support, laying the foundation for stable construction of the upper structure.
[0034] Foam board 2 is vertically positioned on the upper surface of bamboo plywood 1, precisely aligned with the center line of the expansion joint. A filling layer is applied to the bamboo plywood 1, covering the areas on both sides of the foam board 2. This filling layer not only covers the bamboo plywood 1 but also at least partially covers the sidewalls of the foam board 2, typically forming a slope sloping towards the top of the foam board 2. A first pouring layer 41 is cast over the upper surface of the filling layer. This first pouring layer 41 is located on both sides of the foam board 2, and its final upper surface is precisely leveled to be flush with the upper surface of the foam board 2. This layer constitutes the bridge deck pavement section directly traversed by vehicles.
[0035] For the overall structure, during pouring, since the foam board 2 in this embodiment is positioned at the center line of the expansion joint, the interface between the newly poured concrete and the existing pier 7 concrete is kept away from the flexible foam board 2. Thus, on the one hand, the main deformations such as temperature stress and shrinkage stress are concentrated and released in the middle of the gap through the shrinkage and rebound of the foam board 2; on the other hand, the problem of poor flatness caused by performance differences between the new and old concrete at the junction on both sides of the foam board 2 is completely avoided, thereby significantly reducing the risk of edge chipping caused by wheel impacts from the root cause.
[0036] To facilitate pouring, side formwork 6 is also provided on both sides of the foam board 2, and the side formwork 6 is located at least between the foam board 2 and the first pouring layer 41.
[0037] Specifically, in this embodiment, referring to Figure 4 , Figure 5 , Figure 6 and Figure 7The filling layer is an EPS block 312 layer 31 made of geotextile foam. To avoid the pre-embedded steel bars 71 on the pier 7, three methods can be used during implementation: First, through holes 311 for the pre-embedded steel bars 71 to pass through are pre-drilled in the EPS block 312 layer 31. The through holes can also be open holes. Second, the EPS block 312 layer 31 is assembled on site from a pair of standard-sized EPS blocks 312. In this case, the pre-embedded steel bars 71 are positioned in the natural gaps between adjacent EPS blocks 312. Third, the EPS blocks 312 can also be assembled into an EPS block layer by drilling through holes 311 in the EPS blocks 312. (Refer to...) Figure 6 Through holes can also be open holes. EPS, as an expansion joint or filling material, mainly solves key problems such as bridge approach slab settlement and differential settlement through its physical properties.
[0038] Before pouring concrete, it is preferable to set side formwork 6 on both sides of the foam board 2, especially between the foam board 2 and the first pouring layer 41. The side formwork 6 serves to constrain the shape of the concrete, ensuring a clear pouring outline and accurate dimensions, and in particular, ensuring the forming quality of the slope of the filling layer and the edge of the first pouring layer 41.
[0039] Preferably, a second pouring layer 42 is provided between the two sides of the filling layer and the side of the pier 7. More importantly, the first pouring layer 41 and the second pouring layer 42 are poured and vibrated to compact them simultaneously in an integral molding manner during construction. The integrally molded first and second pouring layers 42 are tightly connected with the old concrete on the pier 7 to form a transition zone with uniform rigidity, which completely eliminates the stress concentration points caused by the sudden change in rigidity between the new and old concrete. This rigid body completely covers and protects the pre-embedded steel bars 71 at the top of the pier 7. Its uniform stress characteristics and good integrity are the fundamental guarantee to prevent the wheel load from causing edge chipping in this critical junction area.
[0040] A second geotextile 52 is installed between the lower end of the filling layer and the pier 7 and the bamboo plywood 1.
[0041] In addition, before construction, the civil engineering construction unit shall clean up the debris on the top of the cap beam; the bridge deck pavement layer shall be made up to the joint of the anchorage zone, and it is forbidden to use square timber to make side formwork and reserve grooves at the ends; the technical requirements for EPS block 312 are: material density ≥30kg / m3, compressive strength ≥250KPa, flexural strength ≥150KPa, and compression modulus should not be less than 3.5MPa. Example 2:
[0042] Reference Figure 3 The structural difference from Embodiment 1 is that the filling layer is a graded crushed stone filling layer 32 made of graded crushed stone through layered filling and compaction. This solution is convenient to use locally sourced materials and has a lower cost.
[0043] In summary, regardless of the filling material used, the function of this filling layer is to provide uniform support for the upper concrete layer, form a smooth transition from the pier 7 to the foam board 2 at the center of the expansion joint, and work with the foam board 2 to absorb some of the deformation. Its slope design helps to smoothly transfer stress.
[0044] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.
[0045] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.
Claims
1. A temporary expansion joint structure provided between two adjacent piers, wherein embedded steel bars are provided on the piers, characterized in that, The temporary expansion joint structure includes bamboo plywood, foam board, filling layer and first pouring layer; The bamboo plywood is placed above the gap between two adjacent piers; The foam board is vertically mounted on the bamboo plywood and is located at the center line of the expansion joint; The filling layer covers the bamboo plywood and is located on both sides of the foam board, at least partially covering the height of the foam board; The first pouring layer covers the filling layer and is located on both sides of the foam board, with its upper surface flush with the upper surface of the foam board.
2. A temporary expansion joint structure according to claim 1, wherein A second pouring layer is provided between the two sides of the filling layer and the pier, and the first pouring layer and the second pouring layer are integrally formed.
3. A temporary expansion joint structure according to claim 1 or 2, wherein The filling layer is an EPS block layer made of geofoam plastic.
4. A temporary expansion joint structure according to claim 3, wherein A first geotextile is provided between the filling layer and the first pouring layer.
5. A temporary expansion joint structure according to claim 1, wherein The filling layer is a graded crushed stone filling layer made of graded crushed stone.
6. A temporary expansion joint structure according to claim 1, characterized in that, A second geotextile is provided between the lower end of the filling layer and the pier and the bamboo plywood.
7. A temporary expansion joint structure according to claim 1, wherein Side templates are also provided on both sides of the foam board, and the side templates are located at least between the foam board and the first pouring layer.
8. A temporary expansion joint structure according to claim 3, wherein The EPS block layer has several through holes for the pre-embedded steel bars to pass through; or, the EPS block layer is composed of several EPS blocks spliced together, and the pre-embedded steel bars are located in the gaps between adjacent EPS blocks.
9. A temporary expansion joint structure according to claim 1, wherein The length of the bamboo plywood extending beyond the outer edge of the gap between the two ends of the pier shall not be less than 10 centimeters.
10. A temporary expansion joint structure according to claim 9, wherein The bamboo plywood floor is supported by several reinforcing bars, and the spacing between adjacent reinforcing bars is no more than 30cm.