JP2642289B2 - Joint structure induced by concrete slab - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induced joint structure used for concentrating cracks generated in a concrete slab such as a concrete slab or a post-cast concrete slab in a double slab structure. Things.

[0002]

2. Prior Art and Problems to be Solved by the Invention
Conventionally, as an induced joint structure applied to this type of concrete slab, as shown in FIG.
It is generally known that a cutter joint 21 having a depth of 1/5 to 1/3 of the thickness of the concrete slab is applied to the surface of a concrete slab. However, in this structure, since the reinforcing bars 22 buried in the concrete slab are continuous at the joints, the effectiveness of the cutter joints 21 is deteriorated, and the function as the induced joints cannot be sufficiently exhibited. .

In order to cope with this problem, the reinforcing bar 22 is cut by a cutter as shown in FIG.
Are also discontinuous. However, this structure requires too much time for cutting with the cutter, and when an eccentric load is applied to the opposing concrete slab bordering the cutter joint 21, the concrete slab 20 may shift vertically and the concrete slab 20 may be stepped. There is something.

[0004] For this reason, as shown in FIG.
22 is also arranged so as to be discontinuous at the position where the cutter joint 21 is applied, and a structure for preventing the concrete slab 20 from shifting in the vertical direction is also adopted. However, with this structure, it takes time and effort to accurately perform the work of installing the slip bar 23.

On the other hand, FIG. 12 shows a structure in which a steel fiber 24 is mixed in concrete instead of the reinforcing bar 22, and the work of arranging the reinforcing bar is omitted. The problem with this structure is that the depth of the cutter joint 21 is
If the depth is not more than 1/3, the function as the induced joint is not sufficiently exhibited, and if the cutter joint is deep, it takes too much time to cut with the cutter.

[0006] As described above, the induced joint structure conventionally used for concrete slabs for effectively concentrating cracks has drawbacks such as complicated and time-consuming work and a long construction period. there were.

The present invention has been made in view of the above-mentioned circumstances, and has as its object a simple structure which does not shift in the vertical direction and can be easily formed in a short period of time. It is an object of the present invention to provide an induced joint structure of a concrete slab capable of effectively realizing the concentration of cracks at the induced joint.

[0008]

According to the induced joint structure of the present invention, a sectional defect is generated in the induced joint of the concrete slab, and shrinkage cracks are induced at the intended position on the surface of the concrete slab. A slit joint material is buried below the induced joint. In addition, the slit joint material forms a concave portion and a convex portion on opposing concrete surfaces separated by the joint material, and forms a shear key that restrains the vertical displacement of the opposing concrete surface.

[0009] Then, as shown in FIG. 3, the concrete slab is caused to have a cross-sectional defect by the thickness obtained by adding the depth Ha of the cutter joint and the height Hb of the slit joint material. In this case, it is easier to concentrate the shrinkage cracks at the joint positions.

[0010] In the concrete surface of the opposing concrete slab separated by the slit joint material, one of a concave portion and a convex portion formed by a slit joint material having a substantially inverted T-shaped or Z-shaped cross section. The concrete slabs can be restrained from moving in the vertical direction so as to have a strong structure.

Further, the upper end of the slit joint material is covered with a water-expandable rubber to be waterproof.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view showing a concrete joint structure according to the present invention;

In a concrete slab 2 such as a soil space or a post-cast concrete slab (see FIG. 8) in a double slab structure, an induced joint portion used to concentrate cracks generated in the slab 2 on the induced joint 3. Structure 1
(See FIG. 1 to FIG. 4). The concrete slab 2 is used to generate a cross-sectional defect in the concrete slab 2 at the induction joint portion and induce a shrinkage crack 4 at an intended position.
The slit joint material 5 is buried under the induction joint 3 provided on the surface of the above.

As shown in FIG. 1, the induced joint structure 1 has a slit joint material 5 continuously formed on the bottom surface of a concrete slab or a post-cast concrete slab immediately below a position where the induced joint 3 is applied. After laying and fixing with nails or cross tape, the reinforcing bar 6 is arranged so as to be discontinuous at the position where the induction joint 3 is applied, and concrete 7 is poured. Thereafter, during the initial stage of hardening of the concrete 7, the joint is formed by applying a joint to a position where the induction joint 3 is to be applied by a cutter.

FIG. 2 shows a reinforced concrete slab 2
1 shows a concrete slab 2 in which a steel fiber 8 is mixed instead.

The slit joint material 5 in this embodiment
As shown in FIGS. 4 and 5, is formed in a substantially inverted T-shaped or Z-shaped cross section, and is formed of plastic or metal. Also, as shown in FIG. 3, the slit joint material 5 forms a concave portion and a convex portion on the opposing concrete surface separated by the joint material 5, and restrains the vertical displacement of the opposing concrete surface. It forms a share key.

The induced joint structure 1 having such a configuration.
Concrete slab construction employing the method is performed as described below.

First, the gravel 9 is compacted, and a discarded concrete 10 is poured (see FIG. 1). After the discarded concrete 10 has hardened, the induced joint position is marked on the concrete. Then, the slit joint material 5 is installed by continuously laying the slit joint material 5 at this black position, and fixing the slit joint material 5 with a nail or a cross tape so as not to move at the time of concrete casting.

Next, reinforcing bars 6 or wire meshes are arranged using spacers or the like so as to be discontinuous at the induced joint position and at a position close to the upper surface of the concrete slab. After the concrete is cast, the predetermined joint position is cut by a cutter during the initial stage of concrete hardening.

In this way, the construction of the concrete slab 2 having the induced joint structure 1 is completed.

FIGS. 6 and 7 show another embodiment of the slit joint material 5 buried under the induction joint 3 in the concrete slab 2. The upper end of the slit joint material 5 is provided with a water-expandable rubber 11. It is covered with.

In this manner, the water expanding rubber 11 covering the upper end of the slit joint material 5 can absorb and expand water that enters from the bottom surface of the concrete slab by capillary action. Therefore, it is possible to prevent permeation into the upper surface of the concrete slab.

[0023]

According to the induced joint structure of the present invention, by using the slit joint material and the induced joint together, the induced joint works effectively and the occurrence of random shrinkage cracks can be extremely reduced.

In addition, the concave and convex portions are formed on the concrete surfaces of the opposing concrete slabs separated by the slit joint material by the slit joint material having a substantially inverted T-shaped or Z-shaped cross section. can do. Therefore, the concave portion and the convex portion can restrain one concrete slab from moving in the vertical direction. Further, by covering the upper end of the slit joint material with a water-expandable rubber, it is possible to prevent water from entering by a capillary phenomenon.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of the present invention, in which an induced joint structure in which a soil joint slab is used together with a slit joint material and a cutter joint.

FIG. 2 is a perspective view showing the structure of the present invention, which shows an induced joint structure when steel fiber concrete is used for a concrete slab between soils.

FIG. 3 is an enlarged sectional view showing an induction joint in the induction joint structure of the present invention.

FIG. 4 is a perspective view showing a slit joint material used in the induced joint structure of the present invention.

FIG. 5 is a schematic diagram showing various cross-sectional shapes of a slit joint material used for the induced joint structure of the present invention.

FIG. 6 is a schematic view showing another embodiment of the slit joint material used for the induced joint structure of the present invention.

FIG. 7 is a schematic view showing various cross-sectional shapes of a slit joint material of another embodiment used for the induced joint structure of the present invention.

FIG. 8 is a perspective view showing an embodiment in which the induced joint structure according to the present invention is applied to a post-cast concrete slab having a double slab structure.

FIG. 9 is a perspective view showing a construction example of a conventional induced joint structure.

FIG. 10 is a perspective view showing a construction example of a conventional induced joint structure.

FIG. 11 is a perspective view showing a construction example of a conventional induced joint structure.

FIG. 12 is a perspective view showing a construction example of a conventional induced joint structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Induction joint structure 2 ... Concrete slab 3 ... Induction joint 4 ... Shrinkage crack 5 ... Slit joint material 6 ...
Reinforcing bar, 7 ... concrete, 8 ... steel fiber, 9
... paving gravel, 10 ... concrete concrete, 11 ... water-expandable rubber.

Claims (2)

(57) [Claims] 1. An induction joint portion used for concentrating cracks generated in a concrete slab at an induction joint, wherein the concrete slab at the induction joint portion has a cross-sectional defect and shrinks to a desired position. In order to induce the above, a slit joint material is buried under the induction joint provided on the surface of the concrete slab, and the slit joint material is formed in a substantially inverted T-shaped or Z-shaped cross section, and is formed of plastic or A concave portion and a convex portion are formed on an opposing concrete surface formed of metal and separated by the joint material, and a shear key for restraining a vertical displacement of the opposing concrete surface is formed. Item 4. The joint structure of the concrete slab according to Item 1. 2. The induced joint structure of a concrete slab according to claim 1, wherein the upper end of the slit joint material buried under the induced joint in the concrete slab is covered with a water-expandable rubber.