JP7121545B2 - Method for joining concrete structures and method for joining precast concrete members - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for joining concrete structures and a method for joining precast concrete members.

Conventionally, as a method of joining concrete structures while ensuring water cutoff at joints, a method of filling concrete, non-shrinking mortar, or the like between concrete structures is known (for example, See Patent Document 1.).

Japanese Patent Application Laid-Open No. 2009-264040

However, with these methods, it takes time for the filling material to harden and develop strength, so there is a limit to shortening the construction period. In addition, there is also a concern that cracks may occur in joints due to contraction of the filling material over a long period of time, resulting in a decrease in water resistance and durability. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for joining concrete structures and a method for joining precast concrete members, which are capable of shortening the construction period while ensuring the waterproofness and durability of the joints.

A concrete structure joining method of the present invention comprises a composite structure preparing step of preparing a plurality of composite structures each having a concrete structure and a resin member containing a thermoplastic resin and fixed to a surface of the concrete structure; and a resin member welding step of welding the resin members of the composite structure to each other and connecting the concrete structures to each other via a welded resin portion formed by integrating the resin members.

According to this joining method, the concrete structures are joined together by welding the resin members fixed to the joint end surfaces of the concrete structures. Since the welded resin member hardens relatively quickly and develops strength, the time required for joining the concrete structure can be shortened, and the construction period can be shortened. In addition, since the resin member contains a thermoplastic resin, the joints between the concrete structures are integrated as a continuous body (welded resin portion) by welding the resin members together, and after that, the welded resin portion itself hardly shrinks. Therefore, the welded resin portion is less likely to crack due to shrinkage over a long period of time, and the waterproofness and durability of the joint are ensured. Therefore, it is possible to achieve both shortening of the construction period and securing of water stoppage and durability.

In the concrete structure joining method of the present invention, the resin member contains a silica component, and in the composite structure preparation step, fresh concrete, which is a material of the concrete structure, is cured in contact with the resin member to form a composite structure. You may make it include the process of manufacturing. In the concrete structure joining method of the present invention, the resin member contains a silica component, and the composite structure is produced by curing fresh concrete, which is the material of the concrete structure, in contact with the resin member. You can let it be.

When fresh concrete hardens, tobermorite ( _{5CaO.6SiO2.5H2O} ) is _produced . Therefore, according to the above joining method, the concrete structure and the resin member are firmly joined, and the joint portion between the concrete structure and the resin member has a high water cut-off property.

The resin member welding step may include a step of welding the resin members together by a vibration welding method. The resin member welding step may include a pressurization step of pressurizing the composite structure in a direction to press the heated resin members together.

A method for joining a concrete structure according to the present invention is a joining method for introducing prestress to a plurality of precast concrete members to join the precast concrete members together, and comprises a precast concrete member and an end face of the precast concrete member containing a thermoplastic resin. and a composite member preparing step of preparing a plurality of composite members having a resin member fixed to a precast concrete member through a welded resin portion formed by welding the resin members of the composite members together and integrating the resin members together. and a prestress introduction step of introducing prestress to a plurality of precast concrete members joined in the resin member welding step. A heating step of heating the resin member of the composite member, and a pressing step of pressing the composite member in a direction in which the resin members heated in the heating step are pressed against each other with a pressure smaller than the prestress in the prestress introduction step. have.

Advantageous Effects of Invention According to the present invention, it is possible to provide a method for joining concrete structures and a method for joining precast concrete members, which are capable of shortening the construction period while ensuring the waterproofness and durability of the joints.

1 is a perspective view of multiple composite members used in the joining method of the present invention; FIG. FIG. 2 is a front view showing an enlarged vicinity of joint end surfaces of the composite members shown in FIG. 1 ; (a) to (c) are cross-sectional views showing a method of manufacturing a composite member. (a) to (c) are front views showing a method of joining composite members. (a) is a plan view showing an enlarged surface of a resin member, and (b) is a cross-sectional view of the resin member.

Hereinafter, an embodiment of a method for joining concrete structures according to the present invention will be described in detail with reference to the drawings. The joining method of the present embodiment is used for joining concrete structures together at a construction site of a concrete building, and is particularly used for a use where waterproofing of joints is required.

In this embodiment, as shown in FIG. 1, a method of joining precast floor slabs 5 (concrete structures, precast concrete members) used for road bridges will be described as an example. By this joining method, a plurality of precast floor slabs 5 are continuously connected in the bridge axis direction. Ultimately, prestress is applied to a plurality of precast floor slabs 5 arranged in the direction of the bridge axis, and the precast floor slabs 5 are strongly connected to each other, thereby constructing a road bridge slab (concrete structure). The joining method of this embodiment includes a composite member preparation step, a resin member welding step, and a prestress introducing step, which will be described below.

(Composite member preparation process)
In the composite member preparing step, a plurality of composite members 3 (composite structures) are prepared as shown in FIGS. The composite member 3 is a structure in which a resin member 9 is fixed in advance to a joint end surface 7 of a precast floor slab 5 to be jointed. That is, each composite member 3 is a structure having a precast floor slab 5 to be joined and a resin member 9 fixed to the surface of the precast floor slab 5 . In the composite structure preparation process, for example, a plurality of composite members 3 manufactured in advance at a factory are carried to the road bridge deck construction site.

The resin member 9 is in the shape of a thin plate or a sheet, and is fixed to the joint end face 7 to be joined. The resin member 9 is mainly composed of thermoplastic resin. As this thermoplastic resin, for example, polypropylene (PP), polycarbonate (PC), ABS resin, nylon, EVA resin, or the like is used. The resin member 9 may contain different materials such as polymer cement, sand, fine limestone powder, and fibers. Moreover, the resin member 9 contains a silica (SiO ₂ ) component. Fly ash may be contained in the resin member 9 as a silica source.

The composite member 3 is manufactured at a factory, for example, by the following method. As shown in FIG. 3(a), the resin members 9 are placed at both ends of the concrete formwork 11, and fresh concrete C is poured into the concrete formwork 11 as shown in FIG. 3(b). is set. In order to form the later-described insertion holes 13 in the precast floor slab 5, the sheath pipe 12 is installed in advance in the space into which the fresh concrete C is poured. A hollow portion of the sheath tube 12 functions as an insertion hole 13 for inserting a tendon 15, which will be described later. Further, the resin member 9 may also be provided with the insertion holes 13 at corresponding positions in advance. Further, although detailed illustration is omitted, reinforcing bars are installed in advance in the space into which the fresh concrete C is thrown.

The charged fresh concrete C hardens in contact with the resin member 9 and becomes the precast floor slab 5 . Here, when the fresh concrete C hardens, the chemical reaction between the silica component contained in the resin member 9 and the calcium hydroxide contained in the fresh concrete C causes calcium silicate hydrate to form during the cement hydration reaction process. Tobermorite (5CaO 6SiO ₂ 5H ₂ O), which is a kind of Therefore, the precast floor slab 5 and the resin member 9 are firmly joined together, and the joint portion between the precast floor slab 5 and the resin member 9 is highly waterproof. After that, as shown in FIG. 3(c), the concrete formwork 11 is removed, and the composite member 3 is completed. In placing the fresh concrete C described above, the resin member 9 may function as an embedded formwork. In this case, immediate release molding of the composite member 3 is possible, and the manufacturing efficiency is improved.

(Resin member welding process)
The subsequent resin member welding step is performed at the road bridge deck construction site. In the resin member welding step, the precast floor slabs 5 are joined together by welding the resin members 9 of the adjacent composite members 3 together. The processing of the resin member welding process will be specifically described below. In the following description, as shown in FIG. 2, one joint between the precast floor slabs 5 will be mainly described, but in the resin member welding process, other joints are also subjected to the same process.

First, as shown in FIGS. 1 and 2, adjacent composite members 3 are installed so that their joint end faces 7 face each other. Then, the resin member 9 on the joining end surface 7 is heated, and the resin member 9 is melted by heating (heating step). The heating temperature of the resin member 9 at this time may be set according to the characteristics of the material of the resin member 9, and is, for example, 80 to 500.degree. As a method for heating the resin member 9, various heating methods can be adopted. The resin member 9 may be heated by, for example, a heater, a heating wire, or the like, or may be heated by a heating method using a laser or electromagnetic induction. A heating wire may be installed in the resin member 9 or the precast floor slab 5 in advance. Alternatively, a heating method may be employed in which a high-temperature metal plate or the like is sandwiched between the facing resin members 9 .

Next, as shown in FIG. 4( a ), the tendon 15 is inserted through the insertion hole 13 over the plurality of composite members 3 , and tension is applied to the tendon 15 . Due to this tension, as shown in FIG. 4(b), the two melted resin members 9 are butted against each other, and a pressure P is applied in the direction in which the resin members 9 are pressed against each other. process). As the tendon 15, PC steel is used, for example.

In this case, the pressure P is enough to weld the resin members 9 together. Therefore, the tension force applied to the tendon 15 here is lower than the tension force applied in the prestress introducing step, which will be described later. Specifically, while the pressure applied to the joint end surfaces 7 in the prestress introducing step described later is, for example, 2.0 to 4.0 MPa, the pressure applied to the joint end surfaces 7 in this pressurizing step is, for example, It is 0.3 to 0.5 MPa. The above pressure may be appropriately set according to the characteristics of the material of the resin member 9 . It should be noted that if the pressure P is too large, the melted resin protrudes greatly from the joint end surface 7, which is not preferable. As described above, the tendon 15 used in the post-process (prestress introduction process) is used to apply the pressure P to the composite member 3, so a pressure means for welding the resin member 9 is prepared separately. you don't have to. However, the method of applying the pressure P is not limited to the method of tightening the tendon 15, and various other pressure means can be employed.

After that, as shown in FIG. 4(c), when the temperature of the resin member 9 decreases due to heat radiation and rehardening occurs while the application of the pressure P continues, the two resin members 9 are welded together and integrated. A resin portion 19 is generated. As a result, the precast floor slabs 5 are joined to each other via the welding resin portion 19 . Then, the welding resin portion 19 is completely hardened and the joining of the precast floor slabs 5 is completed.

As a method for welding the resin members 9 to each other, a vibration welding method may be employed. When the welding method is adopted, the resin members 9 are pressed together, and one resin member 9 is reciprocated at a frequency of about 200 Hz and an amplitude of 1 to 5 mm, for example. Frictional heat is generated between the resin members 9 due to the reciprocating motion, and the resin member 9 is melted by the frictional heat.

(Prestress introduction step)
After the welding resin part 19 is cured, tension is further applied to the tendons 15 to introduce prestress across the plurality of precast floor slabs 5 . As a result, a plurality of precast floor slabs 5 are connected in the axial direction of the road bridge to complete the road bridge floor slab. In the prestress introducing step, the prestressed connection of the precast floor slabs 5 is applied with a tension required for design. As described above, the pressure applied to the joint end surface 7 in the prestress introduction step is, for example, 2.0 to 4.0 MPa.

The effect of the joining method of this embodiment will be described. According to the joining method, the precast floor slabs 5 are joined together by welding the resin members 9 provided on the joint end surfaces 7 of the precast floor slabs 5 . The welded resin member 9 hardens more quickly than mortar or the like and develops strength, so that the time for joining the precast floor slabs 5 can be shortened, and the construction period can be shortened. That is, the melted resin member 9 rehardens relatively quickly to become the welded resin portion 19 and develops strength, so that the subsequent precast introduction step can be started early, and as a result, the construction period can be shortened. In particular, in the case of road bridge deck replacement work, etc., there are many cases in which the work period is limited, and there is a strong need to shorten the work period.

If the resin member 9 is mainly composed of a thermosetting resin such as epoxy resin, the uncured resin member 9 is placed between the joint end faces 7 of the precast floor slabs 5 and heated to cure. A series of work will be carried out at the construction site. Further, even if the resin member 9 is a room-temperature-curing adhesive, the process of applying the adhesive to the joint end surface 7 will be similarly performed at the construction site.

On the other hand, in the joining method of the present embodiment, since the main component of the resin member 9 is a thermoplastic resin, the composite member 3 is a mode in which the hard resin member 9 is fixed to the precast floor slab 5. It is possible to operate such that it is manufactured in a factory in advance and transported to the construction site. Then, at the construction site, the work of fixing the resin member 9 to the joint end surface 7 of the precast floor slab 5 can be omitted, and the construction period can be shortened. Alternatively, at the construction site, the work of fixing the resin member 9 to the precast floor slab 5 can be performed in advance at a location other than the position where the composite member 3 is installed (the completed position of the road bridge deck). Construction period can be shortened. In general, thermoplastic resins tend to be less susceptible to deterioration due to ultraviolet rays than thermosetting resins, and the durability of joints is also improved.

In addition, since the joints of the precast floor slabs 5 are filled with the welding resin portion 19 made of a thermoplastic resin after the completion of joining, the water stoppage is higher than when swelling rubber or non-shrinking mortar is filled. high. In the case of swollen rubber or the like, variations in water resistance occur due to variations in the pressure applied between the joint end surfaces 7. On the other hand, the welding resin portion 19 is hardened while being pressurized between the joint end surfaces 7. Variation in the pressure acting on the welding resin portion 19 from the end surface 7 is reduced, and variation in water stoppage is also small. In addition, since the joint surface between the welding resin portion 19 and the precast floor slab 5 is firmly joined by the chemical reaction generated by tobermorite as described above, the joint surface has high water resistance.

Further, since the resin member 9 contains a thermoplastic resin, the joints between the precast floor slabs 5 are integrated as a continuous body (welded resin portion 19) by welding the resin members 9 to each other. Almost no shrinkage. Therefore, there is little possibility that the welding resin portion 19 will crack due to contraction over a long period of time, and the waterproofness and durability of the joint can be ensured. Therefore, it is possible to achieve both shortening of the construction period and securing of water stoppage and durability.

The present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art, including the embodiment described above. Moreover, it is also possible to configure a modified example using the technical matters described in the above-described embodiments. You may use it, combining the structure of each embodiment suitably.

In the embodiment, the method for joining the precast floor slabs 5 used for road bridges has been described, but the present invention is not limited to this, and can be applied to various methods for joining concrete structures. Moreover, although the example in which three or more precast floor slabs 5 are continuously joined has been described in the embodiment, the joining method of the present invention can also be applied to joining two concrete structures. Moreover, the present invention is not limited to a method for joining concrete structures that are joined by introducing prestress, and the prestress introducing step is not essential.

As described above, the vibration welding method may be adopted as the method for welding the resin members 9 together. When the vibration welding method is adopted, the resin member 9 needs to have a shape that facilitates the transmission of frictional force. (The surface facing the other resin member 9) preferably has an uneven shape. From this point of view, a large number of V-shaped grooves 23 may be formed in a grid pattern on the entire surface of the resin member 9, as shown in FIG. In this case, the interval between the V-grooves 23 is preferably 3 to 10 mm. When the concrete structure to be joined is a box-out member or a lotus root column beam, it is difficult to manufacture the uneven resin member 9 as described above. A method of heating the resin member 9 with a hot wire) is preferably adopted.

Further, the back surface of the resin member 9 (the surface fixed to the precast floor slab 5) may be uneven. In this case, the integrity between the precast floor slab 5 and the resin member 9 is mechanically improved. In addition, the uneven shape functions as a shear key, and shear stress can be transmitted between the precast floor slab 5 and the resin member 9 .

In the embodiment, the composite member 3 is manufactured by curing the fresh concrete in contact with the resin member 9, but the resin member 9 is attached to the joint end surface 7 of the cured precast floor slab 5 with an adhesive or the like. The composite member 3 may be produced by fixing. Also, the resin member 9 may not contain a silica component.

3... Composite member (composite structure), 5... Precast floor slab (concrete structure, precast concrete member), 9... Resin member, 15... Tendon, 19... Welded resin part, C... Fresh concrete.

Claims (3)

A joining method for introducing prestress to a plurality of precast concrete members to join the precast concrete members,
a composite member preparing step of preparing a plurality of composite members each having the precast concrete member and a resin member containing a thermoplastic resin and fixed to an end surface of the precast concrete member;
a resin member welding step in which the resin members of the composite member are welded to each other, and the precast concrete members are joined to each other via a welded resin portion formed by integrating the resin members;
a prestress introducing step of introducing prestress to the plurality of precast concrete members joined in the resin member welding step;
The resin member welding step includes:
a heating step of heating the resin member of each of the composite members;
A method for joining precast concrete members, comprising a pressurizing step of pressurizing the composite member in a direction in which the resin members heated in the heating step are pressed against each other with a pressure smaller than the prestress in the prestress introducing step. . The resin member contains a silica component,
The composite member preparation step includes:
2. The method of joining precast concrete members according to claim 1, further comprising the step of hardening fresh concrete, which is a material of said precast concrete member , in contact with said resin member to fabricate said composite member . The resin member contains a silica component,
The composite member is
2. The method for joining precast concrete members according to claim 1, wherein fresh concrete, which is a material of said precast concrete members , is produced by hardening while in contact with said resin member.

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