JP2808388B2 - Method of filling concrete into steel frame - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete filling method capable of uniformly filling a steel frame uniformly without vibration compaction.

[0002]

2. Description of the Related Art The specifications of conventional ordinary concrete have been determined as follows. The index of workability of concrete placing is shown by slump value. In the concrete mix design, the slump value is determined by the workability. The slump value is determined by the unit water amount if the fine aggregate ratio (s / a) is constant. Concrete strength is determined by the water / cement ratio (W / C).

Accordingly, when the slump value is increased to improve workability, the amount of water (W) increases, and the amount of cement (C) increases to secure necessary concrete strength. When the amount of water and cement (the amount of the paste) increases, the aggregates are easily separated (when the strength is the same), and in addition, the shrinkage rate increases, and problems such as cracks occur. On the other hand, if the slump value is increased, material separation occurs.

[0004] By the way, in the case of a construction method in which a steel frame segment in which a steel frame is filled with concrete is used as a shield tunnel segment, ordinary concrete as conventionally used for RC construction is used as the concrete for filling. I was using. However, in the case of conventional ordinary concrete, the slump value is small as described above, the maximum aggregate size is 2/3 or less of the minimum reinforcing bar interval, and the air amount is 4.
Since it was about 0%, the following problems were encountered when filling the steel frame.

[0005] Unless compacted by vibrations, the steel frame cannot be filled. If compacted excessively, material separation occurs, the breathing rate is high, bubbles are generated frequently, and particularly, holes are formed in the steel material of the steel frame. If there is, there is a problem that aggregate separated around the aggregates. It is difficult to completely fill the steel frame with the concrete even if vibration is applied, and a gap may be formed between the steel material and the concrete. Since the concrete surface flaps due to vibration, it is necessary to iron the concrete surface, and that ironing must be done several times depending on the degree of hardening after watching for the concrete to have a certain hardness In addition, the work time is long, and the work must be performed for each steel frame. Due to the compaction by vibration compaction, there are many places that require manual work, including ironing, making automation difficult. Because of manual work, the quality was influenced by the skill level. Equipment for generating noise such as a vibrator and a vibration table was required.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to automatically and uniformly fill a space between steel materials of a steel frame, a cover portion of a steel material, and every corner without vibration compaction. In addition, it is an object of the present invention to provide a concrete filling method capable of forming a high-quality concrete-filled steel frame structure without the necessity of ironing, and with less influence of breathing, material separation and air after filling.

[0007]

According to the present invention, water, cement, fine aggregate, coarse aggregate, admixture of admixture and fine powder are used as raw materials, the fine aggregate ratio is 45 to 55%, and water / ( Cement + admixture) ratio is 25-35%, slump flow is 55cm-7
A highly-fillable concrete compounded so as to have a volume of 5 cm and an air volume of 1.5 to 3.0% is used.

[0008] The steel frame is closed with a cover plate with the opening surface of the steel frame facing upward, and the highly-fillable concrete is filled into the steel frame by the flow pressure of its own weight from the concrete filling opening provided in the cover plate. After the concrete is poured, the concrete is pressurized from the outside through the concrete filling port as needed, and the cover plate is removed after the concrete reaches a predetermined degree of hardening.

[0009]

In the present invention, it is intended to fill the steel frame without compaction and with good filling properties, and to reduce the problems after filling. Therefore, the viscosity was adjusted with a fine powder admixture. Use concrete. That is, by using the fine powder admixture, the apparent W / C, that is, the water / (cement + admixture) ratio is reduced without changing the water / cement ratio (W / C) (50% or less). By giving the concrete an appropriate viscosity, the fluidity and the filling property to the steel frame are ensured without reducing the strength.

[0010] Then, the steel frame is closed with a cover plate with the opening surface facing upward, and the concrete is removed from the concrete filling port provided in the cover plate by its own weight without giving a vibration from a hopper or the like. It flows into the steel frame until it is full due to its fluidity, and is finally pressurized from the outside to eliminate the filling gap and provide a concrete surface that does not require ironing.

[0011]

Embodiments of the present invention will be described below. In the present invention, the mixing ratio of concrete is determined according to the following design method and procedure. 1) Determination of unit amount of water and cement In conventional compounding design of ordinary concrete, first, the unit water amount is determined in order to secure a slump required for concrete construction, and the W / C required to achieve the design concrete strength. The amount of cement was determined from the relationship.

For the concrete used in the present invention (hereinafter referred to as the present concrete), C / W corresponding to the design strength is obtained from the relationship between the concrete strength σ and C / W shown in FIG. The unit cement amount C is determined. That is, in the present concrete, since the required slump flow value is determined by the admixture as described later, the unit water amount is determined regardless of the slump flow. For example, the unit water amount W is set to about 160 to 175 kg / m ³ .

2) Determination of admixture In the present concrete, in order to maintain the material separation resistance necessary for ensuring workability, a fine powder having a Blaine specific surface area of 2,500 cm ² / g or more is added as an admixture. The amount of the admixture to be added is determined by the following filling test using an L-shaped box as shown in FIG. 4 (hereinafter referred to as an L-shaped box test). The L-shaped box 3 is formed by connecting a vertical box 4 and a horizontal box 5 each having an open upper surface in an L-shape, and a plurality of baffle rods 7 imitating a reinforcing bar are filled in the communication ports 6 of the boxes 4. The communication port 6 is provided vertically or horizontally at a predetermined interval (for example, 50 mm) selected from the target structure so that the communication port 6 can be opened and closed by a weir plate 7a.

The method of this L-shaped box test is as follows.
Is closed, concrete is put into the vertical box 4, the weir board 7a is opened, and the concrete is moved to the horizontal box 5 through the communication port 6 by its own weight. In the case of concrete having sufficient filling performance, all of the concrete moves from the vertical box 4 to the horizontal box 5. However, in the case of hard concrete or soft and easily separated concrete, the concrete is blocked by the baffle bar 7. When concrete remains in the vertical box 4, the height between the concrete surface and the upper surface of the vertical box 4 is used as an index value.
Therefore, the optimum value is when the concrete surface in the vertical box 4 and the concrete surface moved to the horizontal box 5 are flush with each other at the same height.

The relationship between the optimum value of the L-shaped box test and the water / (cement + admixture) ratio is as follows. Now, assuming that the W / C is determined from the design strength, the W / C
L-box test is conducted on concrete of which slump flow is adjusted to a predetermined range (for example, 60 to 70 mm) with an admixture, and the condition is satisfied if the gap of the baffle bar 7 is completely passed. become. The relationship between the index value of the L-shaped box test and the water / (cement + admixture) ratio is shown in FIG. 5 from the experiment, and the water / (cement + admixture) ratio is L-shaped within the range of 25 to 35%. There is an optimal value for the box test.

When considering W / C excluding the admixture, W / C
When C is in the range of 25% to 35%, compressive strength of about 600 to 1000 kgf / cm ² can be obtained even with ordinary concrete, but when such high strength is not required, it is not possible to use a large amount of cement. Not only is it economical, but problems such as temperature cracks arise.

Accordingly, in the present concrete, the viscosity is adjusted by using a fine powder admixture without changing the W / C, that is, while maintaining the apparent W / C within a range of, for example, 50 or less. For example, in the case of concrete having a design strength of 240 kgf / cm ² , if the corresponding W / C concrete has a slump flow value of 60 cm, material separation occurs, and blockage also occurs in the L-shaped box test. This phenomenon occurs when the viscosity of the mortar portion is insufficient with respect to the slump flow required for fluidity. Therefore, this concrete does not change the W / C, but the apparent W /
C, that is, a fine powder admixture is used as a means for reducing the water / (cement + admixture) ratio and giving appropriate viscosity.

Therefore, in the present concrete, the amount of the admixture varies depending on the design strength. In other words, in the case where the admixture is conventionally used, the addition ratio of the admixture is determined by the ratio to the weight of the cement. On the other hand, in the present concrete, apparent W
The addition amount of the admixture is determined for the purpose of lowering the / C.

3) Determination of Fine Aggregate Ratio (s / a) As a result of the L-shaped box test, s / a is greatly related to material separation resistance. The relationship between the index value of the L-shaped box test and s / a is as shown in FIG. The optimum s / a varies depending on the production area of the aggregate, but is in the range of 45 to 55%.

4) Determination of the first admixture As the first admixture, for example, a high-performance AE water reducing agent which is generally widely used is used. According to one experiment, the relationship between the admixture addition rate and the slump flow was as shown in FIG. Since this relationship varies depending on the type of cement, the material of the admixture, and the like, the relationship is obtained from an experiment based on the combination of the cement used and the admixture. In this case, the admixture is selected so that the slump flow value is in the range of 60 to 70 cm. In the figure, the amount of the admixture on the horizontal axis indicates% by weight based on (cement + admixture).

5) Determination of the second admixture In order to adjust the slump flow holding time (the time from concrete production to casting on the site), a small amount of a cellulosic thickener is used as the second admixture. Added. Cellulose-based thickeners are also used in conventional underwater inseparable concrete, but the purpose of use in this concrete is different. That is, by using large amounts of thickener 2.0Kgf~3.0Kgf to concrete 1 m ³ in water nondisjunction concrete, it is added to the material separation resistance.

On the other hand, in the present concrete, since the material separation resistance is secured by the admixture of the fine powder as described above, the cellulosic thickener is used only for the purpose of adjusting the slump flow holding time. Therefore, the addition amount is 0-1
The amount is determined to be as small as 00 g / m ^3, and the amount of addition is determined from the relationship shown in FIG. Since this relationship differs depending on the type of cement, admixture, or cellulosic thickener, it is determined by a test using a combination of each material.

Table 1 shows the materials used in the concrete. In this table, low-heating cement (three-component system)
This is a material for superfluid concrete used for comparison with the present concrete as described below.

[0024]

[Table 1]

Table 2 shows six examples of formulations.
From this, the concrete is the present concrete, the general composition of superfluid concrete for comparison, and the general composition of ordinary concrete.

[0026]

[Table 2]

<Fluidity retention characteristics> In order to confirm the fluidity retention characteristics of the concrete shown in Table 2,
The same test kneading as that of the superfluid concrete was performed, and the relationship between elapsed time and slump flow was determined. FIG. 9 shows the relationship. As a result, the following was confirmed. (1) In this concrete, the slump flow during kneading was all within the target range of 55 cm to 75 cm. (2) In this concrete, a slump flow of 60 cm was maintained for about 1 hour and 30 minutes.

A compressive strength test was performed on the superfluid concrete with the present concrete from <Concrete Strength Test> and on ordinary ordinary concrete. FIG.
0 shows the test results. From the results, the following was confirmed. (1) In the case of this concrete, if the amount of cement is about the same, the strength was developed earlier than in and, and the final strength was also higher, showing 50% or more higher strength than ordinary concrete. .

<Pressure Breathing Test> The pressure breathing test measures the pressure breathing rate of the kneaded concrete to determine the deterioration in workability due to dehydration of the concrete during pumping or pressurization. At the same time, you can know the excess water in the concrete. By this test, the material separation resistance of concrete can be assumed. That is, if the pressure breathing rate is large, material separation occurs during pumping or pressurization, and the workability is reduced.

FIG. 11 shows concrete of the above and
The results of a pressure breathing test of a general fluidized concrete in which a fluidizing agent is added to ordinary concrete (the composition is shown in Table 2) are shown below. From the results, the following was confirmed. Compared with (1) fluidized concrete, the pressure breathing rate of this concrete is improved to about 1/3, and the material separation resistance during concrete casting is improved. Therefore, the occurrence of pocking on the concrete surface due to breathing is reduced, so that the adhesion to steel can be greatly improved. (2) The pressure breathing rate of this concrete was comparable to that of superfluid concrete.

<Filling performance test> The above-mentioned L-shaped box test was performed and visually confirmed. As a result, the concrete
It was confirmed that there was no material separation and the steel frame could be filled well by the flow of concrete.

<Measurement of Air Volume> The air volume was measured for the above superfluid concrete and the following concretes. Table 3 shows the measurement results. As a result, it was confirmed that the concrete had a target air volume of 1.5 to 3.0%.

[0033]

[Table 3]

Next, an embodiment of the concrete filling method of the present invention using the above concrete will be described. <Example of Application to Steel Frame Segment for Shield Tunnel Lining> FIGS. 12 and 13 show an example in which the method of the present invention is applied to manufacture of a steel frame segment for shield tunnel lining. The steel frame 8 in this example is formed of H-shaped steel on all four sides, the short side of which is straight, but the long side is curved. The curved outer surface is closed with the steel plate 9 to open the inner surface, and the steel plate 9 is made of steel. A plurality of reinforcing rib members are fixed. As an example,
A steel frame 8 having a filling thickness of 132 mm at the center, 100 mm at the end, a width of 705 mm, and an outer peripheral length of 1410 mm,
With the opened inner surface facing upward, it is closed with a steel lid plate 11 having a flat shape as shown in FIG. 13 and is put through a concrete filling hopper 12 through its injection cylinder 13 and a concrete filling port 14 of the lid plate 11. The concrete as shown in FIG. 4 was filled in the steel frame 8 by the flow pressure due to its own weight. In this case, the valve 15 mounted halfway in the injection cylinder 13
Is opened, concrete is poured into the steel frame 8 until it is full, the valve 15 is closed, and the concrete filling port 14 is opened.
Concrete was pressurized by the concrete pressurizing hydraulic cylinder 16 inserted in the inside. After the filled concrete reached a predetermined degree of hardening, the lid plate 11 was removed.
FIG. 14 is a perspective view of the concrete surface of the steel frame segment for shielding tunnel lining obtained by filling concrete in this way.

[0035]

[Table 4]

On the other hand, FIG. 15 is a perspective view of the concrete surface of a steel frame segment for shielding tunnel lining in which the same steel frame as described above is filled using a vibrator while compacting the concrete by vibration. From the results of such a comparative experiment, the following was confirmed.

(1) In the case of the present invention, the steel frame can be satisfactorily fluid-filled in the steel frame only by natural fall, and compaction by a vibrator is unnecessary. (2) With conventional ordinary concrete, natural filling is difficult,
Finishing work is necessary when casting by human power,
In addition, when compacted by vibration with a vibrator, FIG.
As shown in FIG. 14, the surface became pocked, but in the case of the present invention, the surface finish was extremely good as shown in FIG. As a result, it is possible to mechanize and automate the concrete placing work conventionally performed manually.

The concrete pressurizing hydraulic cylinder 1
6 may have a built-in structure as shown in FIG. That is, a slide plate 19 having a hole 18 is slidably provided in a guide casing 17 crossing the concrete filling port portion 14, and the hydraulic cylinder 16 is fixed to the slide plate 19. In this example, when concrete is poured into the steel frame 8 from the hopper 12, the slide plate 19
When the concrete 18 in the steel frame 8 is pressurized by the hydraulic cylinder 16, the slide plate 19 is slid to slide the hydraulic cylinder 16
With the concrete filling port 14. The pressurization of the concrete can also be performed by pushing the cover plate 11 with a hydraulic cylinder.

[0039]

The effects of the present invention are listed below. Water / cement ratio (W / C) depending on admixture of fine powder
Using a highly-fillable concrete with an appropriate viscosity without changing the concrete, the concrete was allowed to flow into the steel frame from the concrete filling opening of the lid plate by virtue of its own weight and fluidity without vibration. Later, pressure is applied through the concrete filling port, so that it is possible to fill evenly and densely every corner without vibrating compaction between steel materials and between steel materials and the cover portion of the steel material. After removing the concrete, the concrete surface which does not require ironing can be used. The steel frame is closed with the lid facing upward, and the concrete can be filled only by flowing the concrete with its own weight from the concrete filling port provided in the lid, so that the concrete can be compacted by vibration compaction and Since the ironing work is not required, the workability is greatly improved, and the mechanization and automation of the concrete placing work become possible. The water / cement ratio of the concrete to be used is 50% or more for general ordinary concrete, whereas the apparent water / cement ratio is about 25 to 35% in the present invention. As a result, the concrete filled in the steel frame has a small pressure breathing rate and a small shrinkage. Since the pressure breathing rate is small, the workability is good. In addition to the fact that vibration compaction is not required, the pressure breathing rate and air volume are both small, so the occurrence of pock is extremely reduced, and the adhesion performance to steel can be greatly improved, and the concrete after removing the cover plate The surface finish is good and a high quality concrete filling structure can be achieved.

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[Brief description of the drawings]

FIG. 1 is a diagram showing that a maximum distance between aggregates of concrete used in the present invention is determined based on a distance between steel materials of a steel frame.

FIG. 2 is a diagram showing that the maximum aggregate spacing of concrete used in the present invention is determined based on the cover thickness of steel.

FIG. 3 is a graph showing the relationship between concrete strength and cement / water ratio.

FIG. 4 is a perspective view of an L-shaped box used for a filling test.

FIG. 5: Index value of L-shaped box test and water / (cement +
6 is a graph showing a relationship with the (admixture) ratio.

FIG. 6 is a graph showing a relationship between an index value of an L-shaped box test and a fine aggregate ratio.

FIG. 7 is a graph showing the relationship between the addition rate of an admixture and slump flow.

FIG. 8 is a graph showing the relationship between the amount of cellulose-based thickener added and the slump flow holding time.

FIG. 9 is a graph showing a test result of a change over time in slump flow between the concrete used in the present invention and the conventional concrete.

FIG. 10 is a graph showing the results of a compression strength test.

FIG. 11 is a graph showing the results of a pressure breathing test.

FIG. 12 is a cross-sectional view of one embodiment of the concrete method of the present invention applied to manufacture of a steel frame segment for shield tunnel lining.

FIG. 13 is a plan view of a steel lid plate used in the embodiment.

FIG. 14 is a concrete surface view of the steel frame segment manufactured in the embodiment.

FIG. 15 is a concrete surface view of a steel frame segment for shielding tunnel lining in which concrete is compacted by vibration.

FIG. 16 is a cross-sectional view showing another example of a built-in structure of a concrete pressure hydraulic cylinder.

[Explanation of symbols]

 Reference Signs List 8 steel frame 11 steel lid plate 12 concrete filling hopper 13 injection cylinder part 14 concrete filling port part 15 valve 16 hydraulic cylinder

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 14:06 24:24 24:38) (72) Inventor Minoru Nakamura 2-3-6 Otemachi, Chiyoda-ku, Tokyo Shin-Nihon Inside Steel Works Co., Ltd. (72) Inventor Takeshi Komon 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Headquarters (72) Inventor Tetsushi Sonoda 2-5-2 Kitaaoyama, Minato-ku, Tokyo (72) Inventor Susumu Tsuruoka 2-58 Kita-Aoyama, Minato-ku, Tokyo, Japan Intra-company (72) Inventor Hiroshi Taniguchi 2-58 Kita-Aoyama, Minato-ku, Tokyo Co., Ltd. (72 Inventor Kiyoshi Yamagami 1-16-15 Minami-Ikebukuro, Toshima-ku, Tokyo Seibu Construction Co., Ltd. (72) Inventor Etsuo Isegame 1-16-15 Minami-Ikebukuro, Toshima-ku, Tokyo Seibu Construction Co., Ltd. (56 References JP 4 -1649,491 (JP, A) Yasuo Kondo, supervised by one outsider "Concrete Engineering Handbook" 11th edition (48-11-15) Asakura Shoten 71-73 (58) Field surveyed (Int.Cl. ⁶ , DB name) B28B 1/00 B28B 23/02 E21D 11/10 B28B 13/02 C04B 28/02

Claims (2)

(57) [Claims] (1) The steel frame is closed with a lid plate with the opening surface facing upward,
Using water, cement, fine aggregate, coarse aggregate, admixture and admixture of fine powder as raw materials, fine aggregate ratio is 45-55%, water / (cement + admixture) ratio is 25-35%, slump Flow is 5
Highly-fillable concrete mixed so as to have an air volume of 5 to 75 cm and an air volume of 1.5 to 3.0% is filled in the steel frame by the flow pressure of its own weight from the concrete filling port provided in the cover plate. A method for filling concrete into a steel frame, wherein the concrete is poured until the concrete reaches a predetermined degree of hardening, and then the cover plate is removed. 2. The steel frame is closed with a cover plate with the opening surface facing upward,
Using water, cement, fine aggregate, coarse aggregate, admixture and admixture of fine powder as raw materials, fine aggregate ratio is 45-55%, water / (cement + admixture) ratio is 25-35%, slump Flow is 5
Highly-fillable concrete mixed so as to have an air volume of 5 to 75 cm and an air volume of 1.5 to 3.0% is filled in the steel frame by the flow pressure of its own weight from the concrete filling port provided in the cover plate. A method of filling concrete into a steel frame, wherein the concrete is pressurized from the outside through the concrete filling port after the concrete is poured until the concrete reaches a predetermined degree of hardening.