JP2613401B2 - Inorganic grout material for deformed steel bar joints - Google Patents

Description

The present invention relates to an inorganic grout material used for filling and joining the gap of a joint of a deformed steel bar having a relatively large diameter.

b. Conventional technology Conventionally, a plurality of deformed steel bars arranged on beams and columns of a concrete building are generally joined to form one long steel bar.

In this case, two deformed steel bars (having a diameter of approximately 19 to 51 mm) each having an external thread formed on the outer peripheral portion are screwed together with a coupler formed with an internal thread to join the steel bars together. In this way, a method is employed in which deformed steel bars are sequentially joined in accordance with the design specifications of the building to form a long steel bar.

However, since the above-mentioned method is screw-fastened, it was necessary to tighten with a special torquer with a large torque. Therefore, not only the work efficiency is poor, but also when a large number of deformed bars are closely arranged in parallel, the fastening work may not be performed.

To solve this, a coupler with a hole near the center is used, grout material is press-fitted through the hole to fill the butted surface of the deformed steel bar and the gap between the fastened screws, and then hardened to integrate the deformed steel bar. There is a method to make it.

In the joint method using the grout material, an organic grout material such as an epoxy resin was used at first, but an inorganic grout material has recently been developed due to problems of fire resistance and heat resistance.

For example, a composition comprising cement, an expanding material, an ultrafine powder, a high-performance water reducing agent and an aggregate is disclosed in Japanese Patent Application Laid-Open No. 62-78.
334), a method of using the method is to add water to the composition, mix the mixture to form a mortar, press-fit the mixture through holes in a coupler, and join the deformed steel bars.

c. Problems to be Solved by the Invention The conventional grout material has something to be seen in terms of elastic modulus and compressive strength after hardening, but because Portland cement containing coarse particles is used as cement,
When the mortar was press-fitted, coarse particles of several tens of μm or more contained in sand or cement closed the gaps, and the mortars could not be tightly filled in the entire gaps. Therefore, when unevenness occurs inside the joint, and when external stress acts on the joint as a result, cracks occur in the mortar hardened body from the loosely filled portion, especially when joining deformed steel bars having a diameter of 25 mm or more. In addition, the joint performance, that is, the rigidity and the amount of slip are deteriorated.

d. Means for Solving the Problems The present inventors, based on the idea that the conventional method does not consider the size of the particles contained in the grout material, the above-described drawbacks occur, As a result of studying the composition of the grout material and the size of the particles contained in the grout material, the invention of the following inorganic grout material was completed.

That is, the gist of the present invention is an inorganic grout material for a deformed steel bar joint comprising a cement comprising a powder having a particle diameter of 22 μm or less, a water reducing agent and a thickener.

 Hereinafter, the present invention will be described in detail.

In the present invention, it is important to use a cement made of powder having a particle size of 22 μm or less. The powder having a particle size of 22 μm or less as referred to herein is a powder having a 22 μm cumulative passing amount of 100% in a particle size distribution curve measured by a laser diffraction type particle size analyzer. The term “cement” refers to a hydraulic cement used by being mixed with water.

The above cement may be produced by classifying commercially available mixed cements such as ordinary, high-strength, ultra-high-strength, sulfate-resistant, and moderate-heat portland cement, and fly ash cement, and may be pulverized. May be manufactured. The present invention does not particularly limit the adjustment method. The point is to use cement made of powder having a particle diameter of 22 μm or less, which makes it possible to sufficiently tightly fill the gap inside the joint when joining deformed steel bars having a diameter of 25 mm or more. It is not preferable to use a cement containing a powder having a particle diameter of more than 22 μm because the same drawbacks as in the conventional method are often observed. Of course, joining of deformed steel bars having a diameter of 25 mm or less is also possible and is included in the present invention.

In addition, the lower limit of the cement particle diameter is not particularly limited as long as it is in a range where it can be manufactured.

Preferred cement is Portland cement which is early strength or ultra early strength from the viewpoint of shortening the construction period.

In the present invention, the particle diameter was adjusted to 22μm or less,
It is inevitable to mix an appropriate amount of a cement admixture such as a pozzolan-reactive substance, a latent hydraulic substance, a siliceous fine powder, or an expanding material.

The water reducing agent is added to improve the workability by dispersing the particles of the inorganic grout material and to improve the strength by reducing the amount of water to be mixed, and also includes a high performance water reducing agent, a fluidizing agent, and the like. . Specific examples include lignin sulfonic acid type, polycarboxylic acid type, polycyclic aromatic condensate sulfonic acid type (naphthalene type), melamine resin sulfonic acid type, and the like, and a commercially available water reducing agent for cement is used. .

The reason for adding the thickener is as follows. That is,
When jointing deformed bars in the vertical direction, as in the case of column reinforcement, after filling the paste of the inorganic grout material from the holes, until it hardens, it may be sulfurized by its own weight, or at the construction site, it may be deformed bars. Since the joining work and the related work are performed in parallel, the paste may flow down due to vibration or impact at the joint portion, and a void may be generated in a gap inside the joint, thereby deteriorating joint performance. In order to prevent this, it is necessary to increase the viscosity of the paste, so that a thickener is added.

As the adhesive, for example, a water-soluble polymer such as methyl cellulose, ethyl cellulose, polyvinyl alcohol, and sodium polyacrylate is used.

The combination of a water reducing agent and a thickener is preferably a combination of a naphthalene sulfonate-based water reducing agent and an acrylic thickener, or a combination of a melamine-based water reducing agent and a cellulose thickener.

Regarding the mixing ratio, the preferable range of the water reducing agent is 1 to 3% by weight and the thickener is also 0.05 to 0.2% by weight based on the cement.

The inorganic grout material of the present invention may be prepared by mixing the above-mentioned cement, water reducing agent and thickener in the above-mentioned ratios and mixing them with a conventional mixer, and the method is not particularly limited.

Next, an example in which the inorganic grout material of the present invention is used will be described with reference to FIG.

The deformed steel bars 1 and 2 having external threads are fastened with a coupler 4 having a hole 3 near the center. Tightening is performed by machine or manually. After tightening, lock nuts 5,
Setting 6 is more effective. Then, 35-50% by weight of water is added to the pre-made inorganic grout material.
The mixed paste 7 is poured through the hole 3 into an injection machine 8.
Then, press-fit from both ends of the lock nuts 5 and 6 (the coupler 4 when no lock nut is used) until the paste overflows 9. If an early-strength Portland cement having a specified particle size range is used as the cement, the joint can be sufficiently tied by leaving the cement at room temperature for about 3 days.

In addition, in addition to the method of using as an inorganic grout material as described above, the joint performance is the same even if the components are added to water alone to produce a paste. Included in the invention. In short, in the present invention, it is important that a predetermined material is mixed in the paste.

e. Examples Examples 1 to 6 and Comparative Examples 1 to 4 Inorganic grout materials were manufactured using the following materials (a) to (c), and joint performance was examined.

(B) Cement After classifying “Asano Vero Cement” manufactured by Nippon Cement Co., Ltd., and crushing the two types of cement whose particle size was adjusted as shown in Table 1 and granulated blast furnace slag manufactured by Nippon Kokan Co., Ltd. with a ball mill 100% by weight of 22 μm passage, 82.3 of 11 μm passage
20% by weight, classified as 41.1% by weight and a passage of 5.5μm, and "Asano Velo Cement" manufactured by Nippon Cement Co., Ltd.
22 μm passage 100% by weight, 11 μm passage 84.6% by weight, 5.5
A total of three types of cement mixed with 80 parts by weight classified to 43.9% by weight of a μm passage.

(B) Water reducing agent Showa Denko KK's "Merment F-10" (modified melamine type).

(C) Thickener “hi-Metroze 90SH-1500” manufactured by Shin-Etsu Chemical Co., Ltd.
Using "0" (methylcellulose type) in the mixing ratio shown in Table 1, various inorganic grout materials were produced.

Next, the grout material and the amount of water shown in the same table were put into a hand mixer and kneaded for 3 minutes to produce respective pastes. At that time, the amount of water used was determined so that the flow value was in the range of 220 to 260 mm when measured according to the flow test method of JIS R 5201 in order to make the coupler soft enough to allow press-fitting of the coupler.

On the other hand, two joints of SD40 and D38 screw joint deformed steel bars ("Nejitetsukon" manufactured by Tokyo Iron and Steel Co., Ltd.) facing each other with a gap of 10 mm are used. 6
The coupler was fastened with a cast iron coupler having a hole of mm (manufactured by Tokyo Iron and Steel Co., Ltd.), and both sides of the coupler were connected with lock nuts.

In the hole of the coupler of the joint prepared as above,
The above-mentioned paste was pressed in using a manual caulking gun until the paste leaked from the ends of the lock nuts on both sides.

Thereafter, the joint was allowed to stand at 20 ° C. for one week to cure the paste.

Each joint obtained as described above was subjected to a joint performance test in accordance with the test method of the Japan Building Center Rebar Joint Performance Judgment Standard (1982).

The judgment of the performance test was based on the rigidity ratio (A class, 0.7σ _YO E / E ₀ ≧ 0.
9) and the slip amount (A class, 1cδs ≦ 0.3mm). The results obtained are shown in Table 1.

f. Effects of the Invention The present invention relates to an inorganic grout material for a deformed steel bar joint comprising a cement having a defined particle size, a water reducing agent, and a thickener, and when the inorganic grout material is used to press-fit into a void of a joint. In addition, the present invention has an excellent feature that the joint performance does not decrease when a conventional binder is press-fitted, and an integrated joint can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view in the case where the grout material of the present invention is applied to a deformed steel bar joint, and is a view showing the joint and the like in a longitudinal section. 1,2 ... deformed steel bar, 3 ... hole, 4 ... coupler, 5, 6 ... lock nut, 7 ... paste, 8 ... injection machine.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C04B 24:38 7:02) 111: 70 (72) Inventor Kazuya Terado 9946 Kodachi, Yuki City, Ibaraki Prefecture -205 (56) References JP-A-62-78334 (JP, A) JP-B-59-13622 (JP, B2)

Claims (1)

(57) [Claims] 1. An inorganic grout material for a deformed steel bar joint comprising a cement comprising a powder having a particle size of 22 μm or less, a water reducing agent and a thickener.