JP2943588B2 - Forming method of shear key on joint surface of concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a shear key on a concrete joint surface for reinforcing a horizontal joint surface between upper concrete and lower concrete when the concrete is joined above the lower concrete.

[0002]

2. Description of the Related Art Generally, when new concrete is to be transferred above existing concrete located below, the latence generated on the surface of the existing concrete is removed, and before the new concrete is poured, In order to integrate the two concretes, mortar is spread on the surface of the existing concrete, and further concrete is poured on the top of the spread mortar, thereby improving the adhesion between the two concretes and at the joint. The shear strength is improved.

[0003] Among concretes, particularly high fluidity concretes having high fluidity generate less latencies than ordinary concrete, so that the above-mentioned work of removing latencies and leveling of mortar are required. New concrete can be transferred directly onto the surface of the high-fluid concrete without the need. However,
In practice, the surface of cast concrete may be flattened due to the high self-leveling effect of high-fluidity concrete.Therefore, in order to achieve a higher integration of both the upper and lower concrete, for example, the surface of the existing concrete must be The aggregate is exposed by blowing an air water jet, and the unevenness is formed on the surface of the concrete to roughen the joint surface, or after the lower concrete has hardened to some extent, the shear reinforcing bars and the like are connected to the joint surface. The method of standing up is adopted.

[0004]

However, in any of the above-mentioned methods, the processing requires a great deal of labor and trouble, which hinders labor-saving and shortening the construction period of concrete work. Was.

The present invention has been made in view of the above-mentioned problems, and requires no complicated work such as laying of mortar or spraying with a water jet. It is an object of the present invention to provide a method of forming a shear key that can easily form a shear key for improving the shear strength on a horizontal joint surface between concrete and a concrete to be jointed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its gist is to form a large number of recesses formed on the surface of the lower concrete and to strike the upper concrete above the lower concrete. A method of forming a shear key that shears and strengthens a horizontal joint surface between them when joining, wherein at the time of placing concrete below, a floating member having a specific gravity smaller than at least the specific gravity of concrete is partially placed in concrete. Floating on the surface of the concrete in a state of being embedded in the lower concrete, and removing the floating member from the surface of the lower concrete after the lower concrete is hardened, thereby forming a large number of recesses as shear keys on the surface of the lower concrete. A method of forming a shear key on a joint surface of concrete characterized by the following.

Further, in the method for transferring concrete of the present invention, it is preferable to use, as the floating member, a member provided with a weight having a specific gravity greater than that of concrete.

[0008]

According to the method of forming a shear key on a joint surface of concrete according to the present invention, each floating member is placed at a predetermined position immediately after the lower concrete is poured or simply by placing the concrete. Due to its buoyancy, the member floats with at least a portion thereof embedded in concrete. In this state, when the concrete hardens and then the floating members are removed, a large number of recesses having the same shape as the portion of the floating members embedded in the concrete are formed on the surface of the concrete.

[0009] If a member having a weight having a specific gravity greater than that of concrete is used as the floating member, the floating member provided on the surface of the concrete has a predetermined shape due to the weight of the weight. The shear key can be held in a suitable posture to form it, and the lower part of the floating member can be appropriately embedded in the concrete.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method of forming a shear key on a joint surface of concrete according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of the present invention, and FIG. 1 (a) shows an embodiment of a floating member 1 used in the present embodiment. That is, the floating member 1 includes a protruding portion 11 protruding from the upper surface of the concrete, a tubular embedding portion 12 embedded in the concrete, and a cylindrical embedding portion at a boundary between the protruding portion 11 and the embedding portion 12. Projection plate 13 extending outward from the outer periphery of 12
It is composed of Each part of the floating member 1 is integrally formed of a material having a specific gravity smaller than the specific gravity of concrete, such as polyethylene, polypropylene, and vinyl. When the floating member 1 is disposed on the upper surface of the concrete, , As shown in FIG.
By the buoyancy, at least a part of the floating member, that is, in the present embodiment, the buried portion 12 is floated on the surface of the concrete in a state where the buried portion 12 is buried in the concrete.

In order to form a shear key using the floating member 1 having the above structure, a large number of floating members 1
In parallel with or immediately after the lower concrete 2 is cast, the buried portion 12 of the floating member 1 is placed on the surface of the lower concrete 2 in a state of being embedded in the lower concrete 2. . At this time, the overhanging plate 13 of each floating member 1 comes into bearing contact with the surface of the lower concrete 2 and expands the contact area between the floating member 1 and the surface, so that the floating member 1 can be brought into contact with the concrete surface without falling down. Hold it upright.

Thereafter, when the lower concrete 2 has hardened after a predetermined period of time, each floating member 1 is removed from the surface of the lower concrete 2 before a new upper concrete is poured over the lower concrete 2. As shown in 1 (c),
A large number of recesses 3 having the same shape as the buried portion 12 as a shear key are formed on the surface of the lower concrete 2. In addition,
Since the floating member 1 is made of a material such as polypropylene which is easily separated from the concrete, it can be easily removed even after the concrete is hardened. If new concrete is poured over the lower concrete 1 having such a large number of shear keys, the upper concrete is filled in the concave portion 3 so that these joint surfaces become concave and convex surfaces which mesh with each other. Thereby, the adhesion between the two concretes is improved, and the shear reinforcement of the horizontal joint surface can be improved.

FIG. 2 shows another embodiment of the present invention, and (a) shows another embodiment of the floating member. That is, as shown in FIG. 2 (a), the floating member 4 is a weight 41 made of a steel rod such as a reinforcing bar having a specific gravity greater than that of concrete and having a threaded portion at an end.
And a cylindrical floating body 42 which is screwed to the threaded portion of the weight 41 and is made of a material having a specific gravity smaller than the specific gravity of concrete such as polyethylene. The floating member 4 is designed to have a specific gravity smaller than that of concrete as a whole due to the buoyancy of the floating body 42.

In order to form a shear key on the surface of the lower concrete 2 using the floating member 4 having such a configuration, first, as shown in FIG. A large number of floating members 4 are arranged on the surface of the lower concrete 2 immediately after the casting of the concrete or as the concrete is poured. At this time, the floating member 4 causes the upper end thereof, that is, the end to which the floating main body 42 is attached, to protrude from the upper surface of the concrete by the buoyancy of the floating main body 42, and the weight of the weight 41 causes the lower part of the floating main body 42 and the weight 41. Is erected and held in a state of being embedded in the lower concrete 2. Further, according to the floating member 4, even when the floating member 4 is temporarily buried in the concrete during the concrete placing operation, the floating member 4 floats on the surface of the concrete while maintaining the standing state.

After the concrete 2 has hardened, the floating body 42 is removed from the weight 41 by releasing the screwing, and the weight 41 is left on the concrete surface, as shown in FIG. As shown, lower concrete 1
A concave portion 3 as a shearing key can be formed on the surface of the concrete, and the weight body 41 can be projected from the bottom surface of the concave portion 3 to the upper surface of the lower concrete 1. According to this embodiment, similarly to the embodiment shown in FIG. 1, when concrete is newly joined upward, the concave portion 3 forms an uneven surface that meshes with each other, and the weight remaining on the concrete surface. The body 41 serves as a shear reinforcing bar, and further improves the shear reinforcing effect of the horizontal joint surface.

The floating member according to the present embodiment is, as a modified example, an elongated hoop 51 as a weight and a hoop 5 formed by bending a reinforcing bar as shown in FIG.
1 is a spherical air bag having a diameter substantially equal to the inner width d of the air bag 1 and is constituted by an air bag 52 as a floating main body made of a material such as polyethylene which is detachably attached to an end of the hoop streak 51. You can also.

That is, similarly to the floating member 4 shown in FIG. 2, the floating member 5 having the above-described structure can be used to place the floating member 5 immediately after the lower concrete 2 is cast or with the concrete. Many are arranged on the surface of the lower concrete 2. At this time, as shown in FIG. 3 (b), the floating member 5 is levitated on the surface of the concrete by the action of the air bag 52, and the upper end of the hoop streak 51 is moved downward by the concrete 1.
And the lower part of the air bag 4 and the hoop streak 3 is erected and held in the lower concrete 1. Then, if the air bladder 4 of each protruding member 2 is removed after the lower concrete 1 has hardened, FIG.
As shown in (1), the upper end of each hoop bar 3 protrudes from the surface of the lower concrete 1, and a large number of hemispherical concave portions 5 are formed.

[0018]

As described above in detail, according to the method for forming a shear key on a joint surface of concrete according to the present invention, the existing concrete and the concrete to be jointed above the existing concrete can be formed by a simple method. A shear key for improving the shear strength can be easily formed on the horizontal joint surface between the two.

Further, if a member having a weight having a specific gravity at least greater than that of concrete is used as the floating member, the preferred posture of the floating member disposed on the surface of the concrete is determined by the weight of the pair of weights. While being able to hold | maintain, the lower part of this floating member can be embedded in concrete moderately, and a shear key can be formed more easily.

[Brief description of the drawings]

FIG. 1A is a perspective view showing a floating member used in an embodiment of the present invention, and FIGS. 1B and 1C are cross-sectional explanatory views showing a processing procedure according to the embodiment.

FIG. 2A is a perspective view showing a floating member used in another embodiment of the present invention, and FIGS. 2B and 2C are cross-sectional explanatory views showing a processing procedure according to this embodiment. .

FIG. 3 is an explanatory view showing a modified example of the other embodiment.

[Explanation of symbols]

 1,4 Floating member 2 Lower concrete 3 Shear key 41 Weight

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Noritake Takeda 4-640 Shimoseito, Kiyose-shi, Tokyo, Japan Inside Obayashi Corporation Technical Research Institute (72) Inventor Takayoshi Hirata 4-640 Shimoseito, Kiyose-shi, Tokyo, Ltd. Inside Obayashi Technical Research Institute (72) Inventor Masami Kurihara 4-640 Shimoseito, Kiyose-shi, Tokyo Inside Obayashi Technical Research Institute Co., Ltd. (56) References JP-A-4-30060 (JP, A) JP-A-2-101953 ( JP, U) Japanese Patent Publication No. 4-11704 (JP, B2) Japanese Utility Model Publication No. 5-21537 (JP, Y2) (58) Field surveyed (Int. Cl. ⁶ , DB name) E04G 21/02 103 E04G 9 / 10 101 E04G 9/10 105

Claims (2)

(57) [Claims] 1. A method of forming a shear key for forming a plurality of recesses formed on a surface of a lower concrete and for shearing and reinforcing a horizontal joint surface between the upper concrete and the lower concrete when the upper concrete is transferred above the lower concrete. At the time of placing the lower concrete, a floating member having a specific gravity smaller than at least the specific gravity of the concrete is floated on the surface of the concrete while a part thereof is embedded in the concrete, and the floating member is hardened after the lower concrete is hardened. Forming a plurality of recesses as the shear key on the surface of the lower concrete by removing the same from the surface of the lower concrete. 2. The method according to claim 1, wherein the floating member is provided with a weight having at least a specific gravity greater than that of concrete.