JP2009287387A - Reinforcement joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reinforcement joint capable of improving construction efficiency. <P>SOLUTION: Screw-knotted reinforcements 2a and 2b are screwed and inserted into an almost tubular coupler 1 wherein a female screw 6 is formed on an inner periphery. A grout material 3 is infilled into gaps between the coupler 1 and the reinforcements 2a and 2b from an injection hole 4 provided in the central part of the coupler 1. An expansion material is mixed into the grout material 3, and the amount of the mixed expansion material is adjusted so that the bulk strain caused by expansion of the grout material 3 can be set at 2,000 μm or more. A water cementitious material ratio of the grout material 3 is in a range of ≥15 mass% and ≤22 mass% so as to enhance compressive strength of the grout material 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a reinforcing bar joint, and more particularly to a mechanical joint for a reinforcing bar.

  2. Description of the Related Art Conventionally, as a reinforcing bar joint, a mechanical joint is used in which two screw joint reinforcing bars are connected by a coupler, and a pair of lock nuts respectively screwed to the two reinforcing bars are tightened toward both end faces of the coupler. Sometimes. However, in such a mechanical joint, there are problems that it takes a lot of work to install, a number of sets of tools for tightening the lock nut are required, and the lock nut may loosen after tightening. For this reason, in Patent Document 1, screw holes are provided at both ends in the axial direction, and two deformed reinforcing bars are inserted into a sleeve having a protruding portion on the inner peripheral surface, and a bolt that is screwed into the screw hole of the sleeve. Thus, there has been devised a reinforcing bar joint in which the grout material is filled in the sleeve in a state where the two deformed reinforcing bars are pressed against the protruding portion.

JP 2002-256655 A (page 2-3, FIG. 1)

  However, since the reinforcing bar joint described in Patent Document 1 is thicker and longer than the reinforcing bar joint made of a coupler, there is a problem that it is difficult to use in a portion where the reinforcing bars are arranged with high density.

  This invention is made | formed in view of the problem mentioned above, and it aims at providing the reinforcement joint which can aim at improvement of construction efficiency.

  In order to achieve the above object, in the reinforcing bar joint according to the present invention, screw joint reinforcing bars are respectively inserted from both ends of a substantially cylindrical coupler in which a female thread is formed on the inner periphery, and the female thread of the coupler and the male thread of the threaded joint reinforcing bar are connected. A reinforcing bar joint that joins the threaded joint reinforcing bars without using a lock nut by filling a gap between the threaded parts between the threaded reinforcing bars, the expansion material mixed in the grout material, The value obtained by dividing the secant stiffness of the joining rebar at the time of the 20th loading in the elastic range positive / negative repetition test in the first week after filling the gap with the grout material by the dividing line stiffness of the joining rebar at the first loading is 0. The volume strain under uniaxial restraint due to the expansion of the grout material is reduced in the coupler so that the slip deformation amount of the joint rebar at the time of the 20th application is 0.3 mm or less. Stress It characterized in that the entrant 2000μ more.

Here, the volume strain is a value obtained by dividing the change in volume by the original volume, and μ means 10 ⁻⁶ .
When the grout material is mixed in the grout material, the grout material expands in a very narrow gap between the reinforcing bar and the coupler, and when the volume distortion due to the expansion of the grout material reaches 2000 μ or more, the expansion of the grout material becomes a coupler. It is suppressed, chemical prestress is introduced into the coupler, and the mechanical performance of the reinforced joint is improved. In particular, since there is no play between the reinforcing bar and the coupler, the initial strain can be reduced.
According to the present invention, since the lock nuts at both ends of the coupler are not required, it is possible to realize a reinforcing bar joint that can improve the construction efficiency.

Moreover, in this invention, it is preferable that the water binder ratio of the said grout material shall be 15 to 22 mass%.
Here, the water binder ratio is a value obtained by dividing the mass of water contained in the grout material by the mass of the binder containing cement.

There is a correlation between the mechanical performance of the reinforced joint and the compressive strength of the grout material, and the tensile strength of the reinforced joint increases as the compressive strength of the grout material increases. In addition, the compressive strength of the grout material increases as the water binder ratio decreases. In the present invention, the compressive strength of the grout material needs to be about 100 N / mm ² or more. Therefore, based on the experimental results described later, the water binder ratio is set to 22% by mass or less. On the other hand, if the water binder ratio is too small, the filling property of the grout material is deteriorated.

  As described above, according to the reinforcing bar joint according to the present invention, since the lock nuts at both ends of the coupler are not required, a reinforcing bar joint capable of improving the construction efficiency can be realized.

It is an example of embodiment of the reinforcing bar joint which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of an embodiment of a reinforcing bar joint according to the present invention.
As shown in this figure, in the reinforcing bar joint according to the present embodiment, screw joints 2a and 2b are screwed and inserted into a substantially cylindrical coupler 1 having an internal thread 6 formed on the inner periphery. Further, the grout material 3 is filled in the gap between the coupler 1 and the threaded joints 2a and 2b through the injection hole 4 provided in the central portion of the coupler 1. When the grout material 3 is injected from the injection hole 4 of the coupler 1, air is removed from the gap between the coupler 1 and the threaded joints 2 a and 2 b, so that no air vent hole is particularly required.
The expansion material is mixed in the grout material 3, and the mixing amount of the expansion material is adjusted so that the volume distortion due to expansion of the grout material 3 is 2000 μm or more. Moreover, in order to raise the compressive strength of the grout material 3, the water binder ratio of the grout material 3 exists in the range of 15 mass% or more and 22 mass% or less.

  In the reinforcing bar joint according to the present embodiment, the internal thread 6 formed on the inner periphery of the coupler 1 and the external thread 5 on the outer periphery of the threaded joint reinforcing bar 2a, 2b are screwed together, thereby pulling out the threaded reinforcing bar 2a, 2b. In addition to resistance, the mechanical performance of the reinforced joint can be further improved by chemical prestress introduced into the coupler 1 by increasing the strength of the grout material 3 and using the expansion material. In particular, since the play between the screw rebars 2a and 2b and the coupler 1 is eliminated, the initial strain can be reduced.

In the case where two types of cement are used as the grout material and the expansion material is not mixed, the water binder ratio and the age when the test kneading is performed with the water binder ratio being made as small as possible within the range that can be mixed on site. Table 1 shows the compression strength in the day. In the case of cement 1, the water bonding material ratio of about 22% was the minimum, and the compressive strength of the grout material at that time was about 142 N / mm ² . In the case of cement 2, the water binder ratio of about 16% was the minimum, and the compressive strength of the grout material at that time was about 115 N / mm ² . In either case, the result was much higher than the compressive strength of 70 N / mm ² of the conventional grout material.

Next, for rebar joints using a grout material in which an expansion material is mixed in cement 1, the Ministry of Construction, Sumitomo No. 31 (January 31, 1991) [Attachment 1-1] Rebar joint performance criteria Table 2 shows the results of the elastic region positive / negative repetition test shown in FIG. In Table 2, the class A joint standard means a joint that is almost the same as the base material in terms of strength and rigidity, but is slightly inferior to the base material in other respects. The rigidity reduction rate is a value obtained by dividing the secant rigidity of the joining rebar at the time of the 20th application by the dividing line rigidity of the joining rebar at the first application, and the slip amount is the value at the time of the 20th application. This is the slip deformation of the joint rebar. Note that the secant rigidity at this time is the secant rigidity of the joint reinforcing bar at a stress 0.95 times the standard yield point of the base material.
As a result, in the first week, when the expansion material was not mixed, the class A joint standard was not satisfied, but when the expansion material was mixed 5% or more, the result satisfying the class A joint standard was obtained. . In addition, when about 5% of the expansion material is mixed with respect to the cement amount, a measurement result is obtained that the volume strain of the grout material is about 5 × 10 ⁴ μ to 1 × 10 ⁵ μ at the age of 28 days.

DESCRIPTION OF SYMBOLS 1 ... Coupler 2a, 2b ... Screw joint reinforcement 3 ... Grout material 4 ... Injection hole 5 ... Male screw 6 ... Female screw

Claims (2)

By inserting threaded joints from both ends of a substantially cylindrical coupler having a female thread formed on the inner periphery, and filling the grout material in the gap between the female thread of the coupler and the male thread of the threaded joint A rebar joint that joins the threaded joints without using a lock nut,
An expansion material is mixed in the grout material, and the secant rigidity of the joining rebar at the 20th force in the elastic region positive / negative repetition test in the first week after filling the grout material in the gap of the screw joint is applied for the first time. Due to the expansion of the grout material, the value divided by the secant rigidity of the joint rebar at the time of force is higher than 0.5, and the amount of slip deformation of the joint rebar at the 20th force is 0.3 mm or less. A volume joint under uniaxial restraint is 2000 μm or more capable of introducing chemical prestress into the coupler.   2. The reinforcing bar joint according to claim 1, wherein a ratio of the water binding material of the grout material is 15% by mass or more and 22% by mass or less.

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