Connection structure, connection method, and construction method

Abstract

To effectively shorten the construction period while increasing the joint strength of the construction joint. [Solution] A connection structure (40) for the joint between a pre-cast cement-based material (C1) and a post-cast cement-based material (C2), comprising a precast embedded formwork (20) made of fiber-reinforced cement-based material and installed at the joint to connect the pre-cast cement-based material (C1) and the post-cast cement-based material (C2), wherein a roughened portion (G) is formed on at least one part or all of the surface of the precast embedded formwork (20) that is in contact with the pre-cast cement-based material (C1) and the surface of the precast embedded formwork (20) that is in contact with the post-cast cement-based material (C2).

Description

Technical Field

[0001] The present disclosure relates to a connection structure, a connection method, and a construction method, and particularly to a technique suitable for connecting a joint portion of a cement-based material.

Background Art

[0002] Floor slabs of road bridges and the like deteriorate with long-term service. For this reason, repair and reinforcement work for renewing deteriorated floor slabs is required. As one of the countermeasures, there is known a floor slab upper surface thickening work for performing repair and reinforcement by chipping and removing the deteriorated upper layer portion of the existing floor slab, placing a fiber-reinforced cement-based material or the like on the upper surface thereof to integrate them, and thickening the existing floor slab.

[0003] If the floor slab upper surface thickening work is carried out with full traffic closure, the impact on the surrounding traffic environment will be large. For this reason, it is desirable to perform the work in the regulation zone while restricting traffic on one lane and opening traffic on the other lanes. Since the construction work for each lane is sequentially advanced while alternately restricting traffic, a construction joint is formed at the boundary between the fiber-reinforced cement-based material placed in advance during the previous traffic restriction time period and the fiber-reinforced cement-based material placed subsequently during the next traffic restriction time period. At the construction joint, it is required to suppress cracks, opening of joints and the like by increasing the joining force.

[0004] For example, Patent Document 1 discloses a technique in which fiber-reinforced concrete is placed on the upper surface of a floor slab to form a waterproof layer, and an end portion serving as a joint surface of the waterproof layer is subjected to a roughening treatment, thereby increasing the joining force between the waterproof layer and the joint concrete.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In bridge deck thickening work, one way to improve the joint strength of construction joints is to roughen the joint surface of the pre-cast fiber-reinforced cement material by washing it with high-pressure water. However, performing such roughening within a narrow, single-lane traffic zone makes it difficult to carry out the work efficiently. In other words, it is difficult to secure a long construction section to work on during a single traffic restriction period, which leads to a prolonged construction period. Furthermore, the post-treatment of the used water is also necessary, which adds to the time, effort, and cost.

[0007] The technology disclosed herein has been developed in view of the above circumstances, and aims to provide a technology that can effectively shorten the construction period while increasing the bonding strength of the joints of cement-based materials. [Means for solving the problem]

[0008] The connection structure of this disclosure is A connection structure (40) for the joint between a pre-cast cement-based material (C1) and a post-cast cement-based material (C2), The present invention comprises a precast embedded formwork (20) formed from a fiber-reinforced cement-based material and installed at the construction joint to connect the precast cement-based material (C1) and the postcast cement-based material (C2), characterized in that a roughened portion (G) is formed on at least one part or all of the surface of the precast embedded formwork (20) that is in contact with the precast cement-based material (C1) and the surface of the precast embedded formwork (20) that is in contact with the postcast cement-based material (C2).

[0009] In connection structures of other embodiments of this disclosure, The aforementioned pre-cast cement-based material (C1) and the aforementioned post-cast cement-based material (C2) are cast onto the upper surface of the deck slab (10). It is preferable that the precast embedded formwork (20) be installed at the joint between the pre-cast cement-based material (C1) and the post-cast cement-based material (C2) on the upper surface of the floor slab (10).

[0010] In connection structures of other embodiments of this disclosure, Preferably, the precast embedded formwork (20) is equipped with a height adjustment mechanism (30) that can adjust the installation height relative to the upper surface of the floor slab (10).

[0011] In connection structures of other embodiments of this disclosure, The precast buried formwork (20) preferably has a plurality of protruding parts (22, 23) that protrude in the direction of the connection axis between the pre-cast cement-based material (C1) and the post-cast cement-based material (C2), and on which the roughened parts (G) are formed.

[0012] In connection structures of other embodiments of this disclosure, It is preferable that the multiple protrusions (23) are formed in a wedge shape that tapers towards the protruding end (23A).

[0013] In connection structures of other embodiments of this disclosure, The aforementioned precast buried formwork (20) is It is provided with a long plate-shaped base portion (21) installed on the upper surface of the joint portion and extending along the joint portion, and a convex ridge portion (22) that protrudes upward from the base portion (21) and extends in the longitudinal direction of the base portion (21), It is preferable that the multiple protrusions (23) are integrally provided on the convex portion (22).

[0014] The connection method for this disclosure is: A method for connecting the joint between a pre-cast cement-based material (C1) and a post-cast cement-based material (C2), A step of installing a precast embedded formwork (20) made of fiber-reinforced cement material, having a roughened surface (G) formed on at least one part or all of the surface that will come into contact with the precast cement material (C1) and the surface that will come into contact with the postcast cement material (C2), at the construction joint, The method is characterized by including the step of installing the precast buried formwork (20) at the joint, and then sequentially pouring the pre-cast cement-based material (C1) and the post-cast cement-based material (C2).

[0015] The construction method disclosed herein is A method for repairing and reinforcing the existing deck slab (10) of a road bridge (1), A first processing step involves restricting traffic to a portion of the road bridge (1) lanes (L1) to create a first work zone (W), and processing at least the upper surface portion of the existing deck slab (10) within the first work zone (W), A formwork installation step of installing at least one precast embedded formwork (20) in the bridge axis direction (Y) within the first work zone (W) on the existing deck slab (10) near the boundary between one lane (L1) and another lane (L2) adjacent to it, A first pouring and leveling step involves pouring and leveling a pre-cast cement-based material (C1) onto the upper surface of the existing floor slab (10) within the first work zone (W), A second processing step involves opening one of the lanes (L1) to traffic, restricting traffic in the other lane (L2) to create a second work zone (W), and processing at least the upper surface portion of the existing deck slab (10) within the second work zone (W). The process includes a second pouring and leveling step of pouring and leveling a post-cast cement-based material (C2) onto the upper surface of the existing floor slab (10) within the second work zone (W), The precast embedded formwork (20) is formed from a fiber-reinforced cement-based material, and is characterized in that a roughened portion (G) is formed on at least one part or all of the surface that will come into contact with the pre-cast cement-based material (C1) and the surface that will come into contact with the post-cast cement-based material (C2).

[0016] In the above description, to facilitate understanding of the present disclosure, reference numerals used in the embodiments are added in parentheses to the constituent elements corresponding to the embodiments, but each constituent element is not limited to the embodiments defined by the reference numerals.

Effects of the Invention

[0017] According to the technology of the present disclosure, it is possible to effectively shorten the construction period while increasing the joining force at the construction joint portion of the cement-based material.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic diagram illustrating the overall outline of the floor slab top surface thickening construction work. [Figure 2] It is a schematic perspective view showing the embedded formwork according to the present embodiment. [Figure 3] It is a schematic perspective view illustrating the roughened portion formed on the surface of the embedded formwork according to the present embodiment. [Figure 4] It is a schematic cross-sectional view illustrating a connection structure using the embedded formwork according to the present embodiment. [Figure 5] It is a schematic cross-sectional view illustrating the height adjustment mechanism according to the present embodiment. [Figure 6] It is a schematic diagram illustrating the connection method and construction method (first half) according to the present embodiment. [Figure 7] It is a schematic diagram illustrating the connection method and construction method (second half) according to the present embodiment. [Figure 8] It is a schematic diagram illustrating an embedded formwork according to a modified example. [Figure 9] It is a schematic diagram illustrating the embedded formwork installed in the direction perpendicular to the bridge axis according to a modified example. [Figure 10] It is a schematic diagram illustrating an embedded formwork according to a modified example. [Figure 11] It is a schematic diagram illustrating an embedded formwork according to a modified example. [Figure 12] It is a schematic diagram illustrating the connection method (first half) of a comparative example. [Figure 13] This is a schematic diagram illustrating the connection method (second half) of the comparative example. [Modes for carrying out the invention]

[0019] The connection structure, connection method, and construction method according to this embodiment will be described below based on the attached drawings.

[0020] [Overview] First, before describing the details of this embodiment, let's start with an overview of general deck slab thickening work. Figure 1 is a schematic perspective view of bridge 1. Bridge 1 is a road bridge, such as an expressway. Bridge 1 includes, for example, a driving lane L1 and an overtaking lane L2 as lanes on which vehicles travel. That is, the bridge 1 in the illustrated example is a two-lane road bridge with two lanes L1 and L2. Note that the number of lanes of bridge 1 is not limited to the two lanes in the illustrated example, and may be three or more lanes, for example. Alternatively, it may be one lane if the width and shoulder are wide. For convenience, in the following, bridge 1 will be described as a two-lane road.

[0021] Main girders 2 are erected on bridge piers (not shown) of bridge 1. An existing deck slab 10 is installed on top of the main girders 2. A waterproof layer 11 and asphalt pavement AS are provided on the top surface of the existing deck slab 10, starting from the lower layer. A curb 12 is provided either integrally or separately at the end of the existing deck slab 10 in the width direction (direction X perpendicular to the bridge axis). A parapet 14 (or protective fence, etc.) is provided on the top surface of the curb 12. The parapet 14 may be a cast-in-place parapet, a precast parapet, or a steel parapet. The existing deck slab 10 is not limited to the concrete deck slab shown in the example, but may also be a steel deck slab. Furthermore, the existing deck slab 10 does not necessarily have a curb 12.

[0022] In the bridge deck thickening work, traffic is restricted in one lane while the other lane remains open by installing traffic cones (registered trademark) or temporary protective barriers along the bridge axis Y between lanes L1 and L2 (in the illustrated example, lane L1 is restricted and lane L2 is open). Hereafter, the area of ​​the restricted lane (which may also include the shoulder) will be referred to as the work zone W.

[0023] Within the work zone W, first, the deteriorated upper layer of the existing deck slab 10, including the asphalt pavement AS and the waterproofing layer 11, is chipped away using a water jet or breaker, and then cleaned. Note that chipping away may also be done to roughen the surface by processing a few millimeters. After removing the deteriorated parts of the existing deck slab 10, fiber-reinforced cement-based material C is poured and spread evenly, and then sheet curing (not shown) is performed. For example, ultra-high performance fiber-reinforced cement-based composite material (UHPFRC) can be used as the fiber-reinforced cement-based material C. Using UHPFRC, which has high waterproofing properties, allows for the omission of the waterproofing layer 11. Note that depending on the type of fiber-reinforced cement-based material C, sheet curing may be omitted.

[0024] Once the fiber-reinforced cement material C spread within the work zone W has hardened to the strength required for traffic opening, new asphalt ASn will be paved, and the work zone W (i.e., lane L1) will be opened to traffic. After lane L1 is opened to traffic, lane L2 will be restricted, and the same work as on lane L1 will be carried out on lane L2. Once the work on lane L2 is completed, bridge 1 will be fully opened to traffic.

[0025] In the bridge deck thickening work, a construction joint extending in the bridge axis direction Y is formed at the boundary between the fiber-reinforced cement material (hereinafter referred to as "pre-cast fiber-reinforced cement material C1") that is pre-cast on the lane L1 side during the first traffic restriction period and the fiber-reinforced cement material (hereinafter referred to as "post-cast fiber-reinforced cement material C2") that is post-cast on the lane L2 side during the next traffic restriction period. Furthermore, as the construction section becomes longer, a construction joint extending in the direction perpendicular to the bridge axis X is also formed at the end of the construction section in the bridge axis direction Y. At the construction joint, it is required to improve waterproofing performance by increasing the bonding strength between the pre-cast fiber-reinforced cement material C1 and the post-cast fiber-reinforced cement material C2 to suppress cracking and opening. In addition, in order to shorten the construction period, it is required to be able to perform the work efficiently within the narrow work zone W. The embedded formwork 20 according to this embodiment is installed in the construction joint extending in the bridge axis direction Y and / or in the construction joint extending in the direction perpendicular to the bridge axis X, and functions to enhance the joining strength of the construction joint while facilitating workability. The details of the embedded formwork 20 will be described below. In this disclosure, the term "installing the embedded formwork 20 in the construction joint" is a concept that includes various ways of arranging the embedded formwork 20 in the construction joint, such as placing the embedded formwork 20 on the construction joint or fixing the embedded formwork 20 to the existing deck slab 10 by inserting anchors or the like.

[0026] [Buried formwork] Figure 2 is a schematic perspective view showing the embedded formwork 20 according to this embodiment. The embedded formwork 20 is a precast embedded formwork that is manufactured in advance at a factory or the like and transported to the site. Specifically, the embedded formwork 20 integrally comprises a long plate-shaped base portion 21 and a protruding ridge portion 22 extending in the longitudinal direction of the base portion 21. The embedded formwork 20 is manufactured at a factory by pouring fiber-reinforced cement-based material (e.g., UHPFRC) into a predetermined formwork. If UHPFRC is used for the fiber-reinforced cement-based materials C1 and C2 poured at the site, and the embedded formwork 20 is manufactured from UHPFRC having performance equivalent to or better than the fiber-reinforced cement-based materials C1 and C2, or from a material with higher strength than UHPFRC (e.g., Ultra high strength fiber-reinforced concrete (UFC)), it becomes possible to effectively improve the waterproofing performance of the construction joint.

[0027] For convenience, in the following, the side of the base portion 21 on which the protruding ridge portion 22 is provided will be referred to as the "upper surface," and the side of the base portion 21 opposite to the protruding ridge portion 22 will be referred to as the "lower surface." The longitudinal direction of the base portion 21 will also be referred to as the "vertical direction," the short direction of the base portion 21 as the "horizontal direction," and the height direction of the base portion 21 as the "vertical direction." The horizontal direction is the direction in which the embedded formwork 20 connects the pre-cast fiber-reinforced cement material C1 and the post-cast fiber-reinforced cement material C2, and is an example of the connection axis direction in this disclosure.

[0028] The protruding ridge portion 22 is provided on the upper surface of the base portion 21, extending over approximately the entire length of the base portion 21 in the vertical direction. The vertical dimensions of the base portion 21 are not particularly limited, but can be appropriately set within a range that allows it to be loaded onto the cargo bed of a truck or the like to transport the buried formwork 20 to the site. The vertical dimensions of the buried formwork 20 (the sum of the height of the base portion 21 and the height of the protruding ridge portion 22) are also not particularly limited, but it is desirable to make them approximately the same as the height of the fiber-reinforced cement-based materials C1 and C2 (see, for example, Figure 4) that will actually be poured at the site.

[0029] The protruding portion 22 projects upward from the upper surface of the base portion 21. When viewed from above the base portion 21, the protruding portion 22 is formed in a wedge shape (so-called sawtooth shape) having a plurality of roughly V-shaped wedge-shaped portions 23 that protrude laterally and taper towards the protruding end. Specifically, the protruding portion 22 is constructed by forming a plurality of wedge-shaped portions 23 continuously in the longitudinal direction of the base portion 21. The protruding portion 22 and the wedge-shaped portions 23 constitute the protruding portion of this disclosure. The plurality of wedge-shaped portions 23 are arranged so that their protruding ends 23A alternately face opposite directions. That is, adjacent wedge-shaped portions 23 in the longitudinal direction of the base portion 21 are formed to protrude in different directions from each other. In this way, by making the convex portion 22 wedge-shaped, the adhesion resistance and shear resistance between the buried formwork 20 and the pre-cast fiber-reinforced cement material C1 (see Figure 4), and between the buried formwork 20 and the post-cast fiber-reinforced cement material C2 (see Figure 4), can be effectively increased.

[0030] In this embodiment, a roughened surface is formed on the surface of the buried formwork 20 by applying a roughening treatment. Specifically, as shown in Figures 3(A) and (B), a roughened surface G is formed on the surface of the buried formwork 20, excluding the top surface 24 of the raised ridge portion 22. In other words, the upper surface 21A, lateral side surface 21B, vertical side surface 21C, and lower surface 21D of the base portion 21, and the lateral side surface 22A and vertical side surface 22B of the raised ridge portion 22 are subjected to the roughening treatment.

[0031] The roughened surface G can be formed, for example, at a factory that manufactures the embedded formwork 20, by applying a hardening retarder to the corresponding portion of the inner surface of the formwork into which the fiber-reinforced cement material is poured, and then washing it with high-pressure water after demolding. This disclosure does not preclude forming the roughened surface G on the entire surface of the embedded formwork 20, including the top surface 24 of the raised section 22. If the roughened surface G is also formed on the top surface 24 of the raised section 22, it becomes possible to omit the roughening treatment of the top surface 24 in the top surface roughening and paving process performed on-site (see Figure 6(C)) described later.

[0032] Here, the effects of roughening the surface of the buried formwork 20 will be explained with reference to Figure 4. Figure 4(A) is a schematic cross-sectional view of the connection structure 40 using the buried formwork 20 according to this embodiment. Figure 4(B) is a schematic longitudinal cross-sectional view of the connection structure 40 using the buried formwork 20 according to this embodiment. In Figure 4, the fiber FB is schematically shown as a straight fiber, but it may also be a so-called hook-shaped fiber with hooks at both ends.

[0033] As shown in Figures 4(A) and (B), when the surface of the embedded formwork 20 is roughened, numerous fibers FB (e.g., short fibers) contained in the fiber-reinforced cement material (e.g., UHPFRC) protrude from the surface of the embedded formwork 20. These fibers FB cross-link with the pre-cast fiber-reinforced cement material C1 and the post-cast fiber-reinforced cement material C2, which are cast on the upper surface of the existing floor slab 10 after the embedded formwork 20 is installed. In other words, the cross-linking effect of the fibers FB effectively increases the bonding strength between the embedded formwork 20 and the pre-cast fiber-reinforced cement material C1, and between the embedded formwork 20 and the post-cast fiber-reinforced cement material C2. This makes it possible to effectively suppress cracking and opening of the construction joint. Furthermore, the synergistic effect of fiber cross-linking and the wedge shape makes it possible to reliably improve the adhesion resistance and shear resistance of the construction joint. Furthermore, by making the protruding ridge portion 22 of the buried formwork 20 wedge-shaped, even if the fiber FB protruding from the surface of the buried formwork 20 corrodes and disappears, it becomes possible to effectively resist the forces acting on the construction joint.

[0034] Incidentally, as shown in Figure 4(B), the upper surface of the existing floor slab 10 on which the embedded formwork 20 is installed is uneven and not flat due to the removal of the upper layer. Therefore, when installing the embedded formwork 20 on the upper surface of the existing floor slab 10, it is necessary to adjust the installation height so that the lower surface of the embedded formwork 20 is approximately parallel to the upper surface of the existing floor slab 10.

[0035] Therefore, the buried formwork 20 according to this embodiment is equipped with a plurality of height adjustment mechanisms 30 on the base portion 21, as shown in Figure 2. In the example shown in Figure 2, the buried formwork 20 is equipped with a total of six height adjustment mechanisms 30: one pair on one end of the base portion 21 in the vertical direction, one pair on the other end of the base portion 21 in the vertical direction, and one pair on approximately the middle of the base portion 21 in the vertical direction, with a protruding ridge portion 22 in between. The height adjustment mechanisms 30 only need to be provided on at least one end of the base portion 21 in the vertical direction and the other end of the base portion 21 in the vertical direction, and the distance between these one end and the other end can be appropriately provided according to the specific vertical length of the buried formwork 20. The details of the height adjustment mechanisms 30 will be described below with reference to Figure 5.

[0036] [Height adjustment mechanism] Figure 5(A) is a schematic longitudinal cross-sectional view showing an example of the height adjustment mechanism 30 according to this embodiment. As shown in Figure 5(A), the height adjustment mechanism 30 comprises a female screw hole 31 that penetrates the base portion 21 vertically, and a bolt member 32 having a male screw portion that screws into the female screw hole 31. The bolt member 32 is, for example, a hexagonal head bolt or a hexagonal socket head bolt. The height adjustment mechanism 30 is configured to allow easy adjustment of the installation height of the embedded formwork 20 by screwing the bolt member 32 into the female screw hole 31 and adjusting the amount of protrusion of the bolt member 32 from the lower surface 21D of the base portion 21.

[0037] Figure 5(B) is a schematic longitudinal cross-sectional view showing a modified height adjustment mechanism 33. As shown in Figure 5(B), the modified height adjustment mechanism 33 comprises a bottomed female screw hole 34 recessed upward from the lower surface of the base portion 21 and not penetrating the base portion 21, and a bolt member 35 having a male screw portion that screws into the bottomed female screw hole 34. The bolt member 35 is, for example, a socket head cap screw or a head bolt. With the modified height adjustment mechanism 33, the installation height of the embedded formwork 20 can be easily adjusted by adjusting the amount of protrusion of the bolt member 35 from the lower surface 21D of the base portion 21. Furthermore, since the bottomed female screw hole 34 does not penetrate the base portion 21, it is possible to ensure waterproofing. The amount of protrusion of the bolt member 35 can be determined in advance before placing the embedded formwork 20 on the upper surface of the existing floor slab 10.

[0038] The height adjustment mechanism is not limited to the mechanisms 30 and 33 having female and male threads, and can be configured as shown in Figure 5(C), for example. Specifically, in the modified example shown in Figure 5(C), the height adjustment mechanism 36 comprises a bottomed hole 37 that is recessed upward from the lower surface 21D of the base portion 21 and does not penetrate the base portion 21, and a rod member 38 that is inserted into the bottomed hole 37. Preferably, the rod member 38 comprises a plurality of rod members 38 of different lengths. On site, the rod member 38 of the optimal length can be selected from the plurality of rod members 38 of different lengths and inserted into the bottomed hole 37. In this case as well, the installation height of the buried formwork 20 can be easily adjusted. Furthermore, since the bottomed hole 37 does not penetrate the base portion 21, it is possible to ensure waterproofing.

[0039] In this embodiment, by adjusting the installation height of the embedded formwork 20 using the height adjustment mechanisms 30, 33, and 36, the fiber-reinforced cement-based materials C1 and C2 are uniformly filled into the gap between the embedded formwork 20 and the existing floor slab 10. This makes it possible to effectively improve the bonding strength between the embedded formwork 20 and the existing floor slab 10.

[0040] Next, a connection method using the embedded formwork 20 according to this embodiment (construction method for thickening the upper surface of the deck slab) will be described. First, before describing the connection method of this embodiment, a conventional connection method for thickening the upper surface of the deck slab will be described. The conventional connection method is a comparative example of this embodiment.

[0041] [Comparative Example] In the comparative example connection method, as shown in Figure 12(A), the deteriorated upper layer on the lane L1 side of the existing deck slab 10 is chipped away, and then formwork 300 is installed near the boundary between lane L1 and lane L2 on the upper surface of the existing deck slab 10 (chipping and removal / formwork installation process).

[0042] Once the formwork 300 is installed, as shown in Figure 12(B), pre-cast fiber-reinforced cement material C1 is poured and leveled in the area on the lane L1 side of the formwork 300 on the upper surface of the existing floor slab 10 (pouring and leveling process). Once the pre-cast fiber-reinforced cement material C1 has hardened to a certain extent, the formwork 300 is removed as shown in Figure 12(C) before the pre-cast fiber-reinforced cement material C1 has completely hardened (demolition process).

[0043] After removing the formwork 300, before the pre-cast fiber-reinforced concrete C1 has completely hardened, the surface of the pre-cast fiber-reinforced cement material C1, i.e., the construction joint surface, is roughened by washing it with high-pressure water or the like, as shown in Figure 12(D) (construction joint surface roughening process). In some cases, the surface roughening treatment may be performed using a water jet or the like after the pre-cast fiber-reinforced concrete C1 has hardened.

[0044] Once the pre-cast fiber-reinforced cement material C1 has hardened to the strength required for traffic opening, the surface of the pre-cast fiber-reinforced cement material C1 is roughened, and then asphalt AS is paved as shown in Figure 12(E), and lane L1 is opened to traffic (surface roughening and paving process).

[0045] Next, as shown in Figure 13(A), traffic is restricted to lane L2, and the deteriorated upper layer of the existing deck slab 10 on the lane L2 side is chipped away (chipping and removal process). Subsequently, as shown in Figure 13(B), post-cast fiber-reinforced cement material C2 is poured and leveled in the area of ​​the upper surface of the existing deck slab 10 that is on the lane L2 side of the formwork 300 (pouring and leveling process). Once the post-cast fiber-reinforced cement material C2 hardens, the pre-cast fiber-reinforced cement material C1 and the post-cast fiber-reinforced cement material C2 are directly joined together.

[0046] Once the post-cast fiber-reinforced cement material C2 has hardened to the strength required for traffic opening, the surface of the post-cast fiber-reinforced cement material C2 is roughened, and then asphalt AS is paved as shown in Figure 13(C), and lane L2 is opened to traffic (surface roughening and paving process). In other words, the entire road is opened to traffic.

[0047] Conventional connection methods require demolding and joint surface roughening processes to be carried out during the initial traffic restriction period (Figure 12(A)~(E)), resulting in increased construction time due to the increased number of processes. Furthermore, roughening work using high-pressure water must be performed within a narrow work area W, making it difficult to perform the work efficiently. In addition, post-treatment of the water used in the roughening process is required, leading to increased time, effort, and cost.

[0048] In contrast, the connection method according to this embodiment can solve these problems by using the buried formwork 20. The details of the connection method according to this embodiment will be described below.

[0049] [Connection method according to this embodiment] In the connection method of this embodiment, as shown in Figure 6(A), the deteriorated upper layer on the lane L1 side of the existing deck slab 10 is chipped away or the surface is roughened by a few millimeters, and then the embedded formwork 20 is installed near the boundary between lane L1 and lane L2 on the upper surface of the existing deck slab 10 (chipping away and embedded formwork installation process). At this time, the installation height of the embedded formwork 20 is also adjusted as needed. This process is an example of the first processing step and formwork installation step of this disclosure. Note that the processing of the upper layer of the existing deck slab 10 may be other than chipping away or roughening.

[0050] Once the embedded formwork 20 is installed, as shown in Figure 6(B), pre-cast fiber-reinforced cement material C1 is poured and leveled in the area on the upper surface of the existing deck slab 10 that is on the lane L1 side of the embedded formwork 20 (pour-and-leveling process). This process is an example of the first pour-and-leveling process of this disclosure.

[0051] Once the pre-cast fiber-reinforced cement material C1 has hardened to the strength required for opening the road to traffic, the top surface of the pre-cast fiber-reinforced cement material C1 and the top surface (top) of the embedded formwork 20 are roughened, and then asphalt AS is paved as shown in Figure 6(C), and lane L1 is opened to traffic (top surface roughening and paving process).

[0052] In other words, according to the connection method and construction method of this embodiment, the demolding process (see Figure 12(C)) and the joint surface roughening process (see Figure 12(D)) are unnecessary, and the number of steps can be reduced compared to the comparative example. Furthermore, since on-site roughening of the joint surface is unnecessary, work efficiency can be effectively improved. That is, it is possible to secure a longer construction section to be carried out in a single traffic restriction period, and the construction period can be effectively shortened. Moreover, since post-treatment of water is unnecessary, it is possible to effectively reduce time, effort, labor, and costs.

[0053] Once construction on the Lane L1 side is complete, as shown in Figure 7(A), traffic is restricted to Lane L2, and the deteriorated upper layer of the existing deck slab 10 on the Lane L2 side is chipped away or the surface is roughened by a few millimeters (chipping and removal process). This process is an example of the second processing process of this disclosure. Note that the processing of the upper layer of the existing deck slab 10 may be other than chipping and removal or roughening. Subsequently, as shown in Figure 7(B), the post-cast fiber-reinforced cement material C2 is cast and leveled in the area on the Lane L2 side of the embedded formwork 20 on the upper surface of the existing deck slab 10 (casting and leveling process). This process is an example of the second casting and leveling process of this disclosure. Once the post-cast fiber-reinforced cement material C2 hardens, the pre-cast fiber-reinforced cement material C1 and the post-cast fiber-reinforced cement material C2 are joined via the embedded formwork 20. Once the post-cast fiber-reinforced cement material C2 has hardened to the strength required for traffic opening, the surface of the post-cast fiber-reinforced cement material C2 is roughened, and then asphalt AS is paved as shown in Figure 7(C), and lane L2 is opened to traffic (surface roughening and paving process). In other words, the entire road is opened to traffic.

[0054] As described in detail above, in this embodiment, a precast embedded formwork 20 manufactured in advance using a fiber-reinforced cement-based material is installed at the construction joint of the existing floor slab 10, and the pre-cast fiber-reinforced cement-based material C1 and the post-cast fiber-reinforced cement-based material C2 are connected by the embedded formwork 20. At least the surface of the embedded formwork 20 that comes into contact with the pre-cast fiber-reinforced cement-based material C1 and the post-cast fiber-reinforced cement-based material C2 is pre-roughened. That is, the cross-linking effect of the fibers FB contained in the fiber-reinforced cement-based material increases the bonding force between the pre-cast fiber-reinforced cement-based material C1 and the post-cast fiber-reinforced cement-based material C2 via the embedded formwork 20. This makes it possible to effectively suppress cracking and opening of the construction joint.

[0055] Furthermore, by pre-roughening the embedded formwork 20, the on-site roughening work of washing the end faces of the pre-cast fiber-reinforced cement material C1 with high-pressure water can be omitted. This means that work can be carried out efficiently even within a narrow work zone W, and a longer construction section can be secured during a single traffic restriction period, thus effectively shortening the construction period. In addition, post-treatment of water is unnecessary, which effectively reduces labor, effort, and costs.

[0056] [others] Furthermore, this disclosure is not limited to the embodiments described above, and can be modified and implemented as appropriate without departing from the spirit of this disclosure.

[0057] For example, in the above embodiment, the protruding portion 22 of the buried formwork 20 was described as being formed in a wedge shape when viewed from above the base portion 21, but other shapes can be applied as long as they can be removed from the formwork in the factory. For example, as shown in Figure 8(A), the protruding portion 22 (an example of the protruding portion of this disclosure) may be a shape in which semicircular portions protruding laterally are alternately continuous in opposite directions (a so-called wave shape). Alternatively, as shown in Figure 8(B), the protruding portion 22 (an example of the protruding portion of this disclosure) may be a shape in which recesses opening laterally are alternately continuous in opposite directions. Alternatively, as shown in Figure 8(C), the protruding portion 22 may be a straight line provided approximately at the center of the base portion 21 in the lateral direction, and the vertical cross-sectional shape of the buried formwork 20 may be formed in an approximately inverted T shape. Alternatively, as shown in Figure 8(D), the protruding ridge 22 may be a straight line provided at one end of the base portion 21 in the lateral direction, and the longitudinal cross-sectional shape of the buried formwork 20 may be formed in a substantially L-shape. Alternatively, the protruding ridge 22 may be omitted, and the thickness of the base portion 21 may be increased to form the longitudinal cross-sectional shape of the buried formwork 20 in a substantially rectangular shape. Furthermore, when the buried formwork 20 is used in a construction joint extending in the direction X perpendicular to the bridge axis, as shown in Figure 9, the longitudinal end 29 of the buried formwork 20 may be bent in the vertical direction Z to match the shape of the curb.

[0058] Furthermore, in the above embodiment, the embedded formwork 20 was described as having only the protruding ridge portion 22 formed in a wedge shape when viewed from above the base portion 21. However, as shown in Figure 10, it is also possible to make the lateral end of the base portion 21 a wedge shape with multiple wedge-shaped portions in a continuous configuration, so that both the base portion 21 and the protruding ridge portion 22 are wedge-shaped. In this case, only one lateral end of the base portion 21 may be wedge-shaped (see Figure 10(A)), or both lateral ends of the base portion 21 may be wedge-shaped (see Figure 10(B)). Although detailed illustrations are omitted, it is also possible to make the protruding ridge portion 22 straight (Figure 8(C)), a so-called wave shape (Figure 8(A)), or a shape with continuous recesses (Figure 8(B)), and make only the base portion 21 wedge-shaped.

[0059] Furthermore, as shown in Figure 11, by partially cutting out the vertical ends EN, EN' of the buried formwork 20, 20', it is possible to configure the pair of buried formwork 20, 20' to overlap when they are installed continuously in the vertical direction. Specifically, in a top view of the base portions 21, 21', the portion of the base portions 21, 21' that does not overlap with the protruding portions 22, 22' of the ends EN, EN' is cut out. That is, the protruding portions 22, 22' of each end EN, EN' are left intact. The portion of the base portions 21, 21' that is cut out from the ends EN, EN' is different in the horizontal direction for one buried formwork 20 and the other buried formwork 20'. With this configuration, when the embedded formwork 20, 20' is installed continuously in the vertical direction, the lateral surfaces 22A, 22A' of the protruding portions 22, 22' of each end EN, EN' face each other. As a result, the gaps between these opposing lateral surfaces 22A, 22A' are filled with pre-cast fiber-reinforced cement material C1 and / or post-cast fiber-reinforced cement material C2, making it possible to effectively increase the vertical bonding strength of each embedded formwork 20, 20'.

[0060] Furthermore, although the above embodiment illustrates the connection of fiber-reinforced cement systems C1 and C2, the technology disclosed herein can be broadly applied to the connection of other cement-based materials such as ordinary concrete. [Explanation of symbols]

[0061] 1...Bridge, 2...Main girder, C1...Pre-cast fiber-reinforced cement material, C2...Post-cast fiber-reinforced cement material, W...Work zone, L1, L2...Lane, 10...Existing deck slab, 11...Waterproofing layer, 12...Amphibole section, 14...Wall guardrail, AS...Asphalt pavement, 20...Embedded formwork, 21...Base section, 22...Protruding section, 23...Wedge-shaped section, 30, 33, 36...Height adjustment mechanism, 31...Female threaded hole, 32, 35...Bolt member, 34...Bottomed female threaded hole, 37...Bottomed hole, 38...Rod member, 40...Connecting structure, FB...Fiber, G...Roughened section

Claims

1. A connection structure for the joint between pre-cast cement-based material and post-cast cement-based material, The structure comprises a precast embedded formwork made of fiber-reinforced cement material, which is installed at the joint and connects the pre-cast cement material and the post-cast cement material, and a roughened surface is formed on at least one part or all of the surface of the precast embedded formwork that is in contact with the pre-cast cement material and the surface of the precast embedded formwork that is in contact with the post-cast cement material. A connection structure characterized by the following features.

2. The connection structure according to claim 1, The aforementioned pre-cast cement-based material and the aforementioned post-cast cement-based material are cast onto the upper surface of the deck slab. The precast embedded formwork is installed at the joint between the pre-cast cement-based material and the post-cast cement-based material on the upper surface of the floor slab. A connection structure characterized by the following features.

3. The connection structure according to claim 2, The precast embedded formwork is equipped with a height adjustment mechanism that allows adjustment of the installation height relative to the upper surface of the floor slab. A connection structure characterized by the following features.

4. A connection structure according to claim 1 or 2, The precast buried formwork includes a plurality of protruding portions that project in the direction of the connection axis between the pre-cast cement-based material and the post-cast cement-based material, and which have the roughened surface portion formed thereon. A connection structure characterized by the following features.

5. The connection structure according to claim 4, The multiple protrusions are formed in a wedge shape that tapers towards the end of the protrusion. A connection structure characterized by the following features.

6. The connection structure according to claim 4, The aforementioned precast buried formwork is It is provided with a long plate-shaped base portion installed on the upper surface of the joint portion and extending along the joint portion, and a convex ridge portion that protrudes upward from the base portion and extends in the longitudinal direction of the base portion, Multiple of the aforementioned protrusions are integrally provided on the aforementioned ridge portion. A connection structure characterized by the following features.

7. A method for connecting the joint between pre-cast cement-based material and post-cast cement-based material, A step of installing a precast embedded formwork, which is made of a fiber-reinforced cement-based material and has a roughened surface formed on at least one part or all of the surface that will come into contact with the pre-cast cement-based material and the surface that will come into contact with the post-cast cement-based material, at the construction joint; The process includes installing the precast embedded formwork at the joint, and then sequentially pouring the pre-cast cement-based material and the post-cast cement-based material. A connection method characterized by the following:

8. A method for repairing and reinforcing the existing deck slab of a road bridge, A first processing step involves restricting traffic to a portion of the road bridge lanes to create a first work zone, and processing at least the upper surface portion of the existing deck within the first work zone. A formwork installation step of installing at least one precast embedded formwork in the bridge axis direction within the first work zone on the existing deck slab, near the boundary between one lane and another lane adjacent to the aforementioned lane, A first pouring and leveling step involves pouring and leveling a pre-cast cement-based material onto the upper surface of the existing floor slab within the first work zone, A second processing step involves opening some of the aforementioned lanes to traffic, restricting traffic to the other lanes to create a second work zone, and processing at least the upper surface portion of the existing deck slab within the second work zone. The process includes a second pouring and leveling step of pouring and leveling a post-cast cement-based material onto the upper surface of the existing floor slab within the second work zone, The precast embedded formwork is formed from a fiber-reinforced cement-based material, and a roughened surface is formed on at least one part or all of the surface that will come into contact with the pre-cast cement-based material and the surface that will come into contact with the post-cast cement-based material. A construction method characterized by the following features.

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