JP6602228B2 - Method for producing concrete for slip foam method and slip foam method - Google Patents

Description

The present invention mainly relates to a method for producing concrete for a slip form method used in the civil engineering / architecture industry and the like, and a slip form method using the same.

The slip form method is a method suitable for construction of concrete structures having the same cross-sectional shape with long dimensions, such as road-related facilities such as road median strips, circular waterways, gutters, pipe windings, standing walls, and civil engineering structures. Using a self-propelled construction machine equipped with a compacting device and a shaping device, the mold is slipped while shaping and compacting the long-dimension concrete into the same cross-sectional shape as a continuous concrete structure It is a construction method for constructing objects.

The concrete used in the slip-form method retains the fluidity necessary for manufacturing, transportation and construction, and the placed concrete can be sag and struck by its own weight so that the formwork can slip quickly after vibration molding. Is required to have deformation resistance.

Conventionally, as for the concrete used in the slip form method, a kneaded concrete with a small slump is used in order to prevent the occurrence of harami due to its own weight. Since such hard concrete has poor fluidity, when it is manufactured at a ready-mixed factory and transported by an agitator car, it has problems such as hopper blockage at the time of shipment and difficulty in discharging when arriving at the construction site. On the other hand, dump truck transportation also has a problem that quality may be deteriorated during transportation.

For this reason, a method of adding a cement additive in which a water reducing agent and a natural polysaccharide and / or a water-soluble acrylic polymer are blended at a specific ratio has been proposed (Patent Document 1). However, in the method of adding an organic thickener or viscosity modifier on site, the viscosity of the concrete increases and workability decreases, and the concrete tends to adhere to the formwork, resulting in poor finish and impaired aesthetics. There was a problem. Moreover, when the surface water amount of the aggregate increases, there is a problem that sagging and harassment increase.

Japanese Patent Application Laid-Open No. 08-109053

 Therefore, the present invention provides a method for producing concrete for a slip form method, which can suppress the occurrence of sagging and harassment after construction of the slip form method, and can produce a structure that does not adhere to a mold and has an excellent appearance.

The inventors of the present invention have completed the present invention as a result of intensive studies in order to achieve the above object. That is, the present invention provides the following [1] to [3].

[1] A method for producing concrete for a slip foam method comprising kneading at least cement, a polycarboxylic acid-based water reducing agent, a naphthalenesulfonic acid-based water reducing agent, an aggregate, and kneaded water,
Either one of polycarboxylic acid-based water reducing agent or naphthalene sulfonic acid-based water reducing agent is mixed with cement, aggregate, and kneaded water, and before placing on the slip foam formwork at the construction site, the other There is provided a method for producing concrete for a slip foam method, characterized by adding a water reducing agent and kneading.
[2] A method for producing concrete for a slip foam method according to [1], in which concrete containing a polycarboxylic acid-based water reducing agent is kneaded and a naphthalene sulfonic acid-based water reducing agent is post-added at a construction site.
[3] A slip foam method using the concrete for slip foam method manufactured by the method according to [1] or [2] is provided.

FIG. 1 shows a conceptual diagram of the slip form method. It is a construction method in which the concrete 20 is cast on the construction surface 11 while being cast with the slip mold 12, and its front view (a), plan view (b), and side view (c) are shown. The side view (c) represents the concrete 20 after molding without deformation even if the slip mold passes in the direction of the arrow. Actually, as represented by a broken line, an edge slump (vertical change amount A) and a bulge (horizontal change amount B) occur. Here, the slip mold is a mold (mold) attached to a molding machine. In the present invention, “parts” and “%” are units based on mass unless otherwise specified. The concrete in the present invention includes mortar.

 The method for producing the concrete for the slip foam method according to the present invention is a method for producing the concrete for the slip foam method comprising kneading at least cement, a polycarboxylic acid-based water reducing agent, a naphthalenesulfonic acid-based water reducing agent, an aggregate, and kneaded water. Before kneading either a polycarboxylic acid-based water reducing agent or a naphthalene sulfonic acid-based water reducing agent, cement, aggregate, and kneaded water, and placing them on a slip form at the construction site Add another water reducing agent and knead.

The method of kneading the concrete to which either the polycarboxylic acid-based water reducing agent or the naphthalene sulfonic acid-based water reducing agent is added is not limited. For example, all the materials can be put into a mixer and kneaded. Further, the kneading apparatus is not limited, and for example, an omni mixer, a pan type mixer, a biaxial mixer or the like can be used. In addition, the said concrete may be knead | mixed in a ready-mixed factory, and may be kneaded | mixed at a construction site.

The concrete to be kneaded by adding the other water reducing agent at the construction site is within 5 to 20 minutes before being placed on the slip foam form (more preferably) from the viewpoint of suppressing the occurrence of sagging and harassment after the slip form construction. Is preferably kneaded within 5 to 10 minutes. The kneading at the construction site may be carried out with, for example, a mixer (pan-type mixer, biaxial mixer, etc.) installed at the construction site, or when the first concrete is produced at a ready-mixed plant, kneading with a track agitator. May be.

In the present invention, from the viewpoint of workability and fluidity maintenance of the first kneaded concrete, the concrete containing a polycarboxylic acid-based water reducing agent is kneaded, and a naphthalene sulfonic acid-based water reducing agent is post-added to the concrete. It is preferable.
As the polycarboxylic acid water reducing agent, a commercially available polycarboxylic acid high water reducing agent or high performance AE water reducing agent can be used. In the present invention, the polycarboxylic acid-based water reducing agent includes a polycarboxylic acid ether-based water reducing agent. As the naphthalene sulfonic acid water reducing agent, a commercially available naphthalene sulfonic acid high water reducing agent or high performance AE water reducing agent can be used.

In the present invention, when a concrete containing a polycarboxylic acid-based water reducing agent is kneaded and a naphthalene sulfonic acid-based water reducing agent is added to the concrete afterwards, the viewpoint of suppressing the occurrence of sag and harami after the slip-form construction method From the standpoints of workability and fluidity maintenance of concrete and concrete, the polycarboxylic acid water reducing agent is added in an amount of 0.2 to 1.5% (more preferably 0.3 to 1.4%) to the cement. The naphthalene sulfonic acid water reducing agent is preferably added in an amount of 1 to 10 times (more preferably 2 to 9 times) the polycarboxylic acid water reducing agent.

In addition, when concrete containing a polycarboxylic acid-based water reducing agent is kneaded and a naphthalene sulfonic acid-based water reducing agent is added afterwards to the concrete, the polycarboxylic acid type kneaded first from the viewpoint of workability of the concrete, etc. The concrete slump containing the water reducing agent is preferably 4.0 to 12.0 cm (more preferably 5.0 to 11.0 cm). Furthermore, from the viewpoint of suppressing workability during construction of the slip form construction method and occurrence of sagging and harassment after construction, the concrete slump after the addition of a naphthalene sulfonic acid-based water reducing agent is 2.0 to 6.0 cm (more preferably 2.5 to 5.5 cm) is preferable.
The concrete has an air amount of 3.0 to 7.0% by volume, more preferably 3.5 to 6.5% by volume from the viewpoint of durability and the like.

The cement used in the present invention includes various portland cements such as normal, early strength, very early strength, low heat, and moderate heat, various mixed cements obtained by mixing blast furnace slag, fly ash, or silica with these portland cements, limestone. Examples thereof include filler cement mixed with powder, blast furnace slow-cooled slag fine powder, etc., and ordinary ecocement, and one or more of these can be used.

The aggregate used in the present invention is a general term for fine aggregate and coarse aggregate.
As the aggregate, any aggregate such as limestone or quartzite-based natural aggregate, various slag aggregates, heavy aggregate having a specific gravity of 2.8 or more, and recycled aggregate can be used.

 As the kneading water, tap water can be used, but is not limited thereto.

 In the present invention, in addition to the above materials, expansion materials, rapid hardening materials, AE agents, thickening agents, shrinkage reducing agents, polymers, clay minerals such as bentonite, blast furnace granulated slag powder, fine limestone powder, fly ash, silica fume In addition, it is possible to use one or more of admixture materials such as regenerated fine powder and fibers generated when producing regenerated aggregate, or two or more of them in a range that does not substantially impair the object of the present invention. is there.

The concrete for the slip foam method manufactured according to the present invention has a unit cement amount of 250 to 680 kg / m ³ from the viewpoint of workability and strength development, and also the suppression of sagging and harassment after the slip foam method is applied. it is preferable water / cement ratio of 0.25 to 0.50, a unit coarse aggregate bulk volume is 0.60~0.85m ³ / ^{m 3.}

  By using the concrete for slip foam method manufactured by the manufacturing method of this invention, generation | occurrence | production of a sagging and a shampoo can be suppressed after slip form method construction construction. Furthermore, even when the surface water amount of the aggregate fluctuates, it is possible to suppress the occurrence of sagging and harassment. Moreover, the said concrete can manufacture the structure which does not adhere to a formwork but is excellent in aesthetics.

It is a schematic diagram which shows the concept of a slip form construction method.

(1) Material cement: Ordinary Portland cement (manufactured by Taiheiyo Cement)
Fine aggregate: mountain sand (produced in Kakegawa City, Shizuoka Prefecture, surface dry density 2.57g / cm ³ )
Coarse aggregate: sandstone crushed stone 2005 (produced from Sakuragawa City, Ibaraki Prefecture, surface dry density 2.65 g / cm ³ , actual volume ratio 59.6%)
Water: Tap water Chemical admixture: Polycarboxylic acid-based high-performance AE water reducing agent ("Master Glenium SP8SV" manufactured by BASF Japan)
Naphthalenesulfonic acid high-performance water reducing agent (“Mighty 150” manufactured by Kao)
AE agent ("Master Air 202" manufactured by BASF Japan)
AE water reducing agent ("Master Pozzolith No. 70" manufactured by BASF Japan)

(2) Compounding conditions Unit water amount: 140 kg / m ³
Water cement ratio: 42%
Unit coarse aggregate bulk volume: 0.73 m ³ / m ³
Slump (when driven into the mold): 4.0 ± 1.5cm
Air volume: 5.0 ± 1.5% by volume
Prepared.

In the table, PC represents a polycarboxylic acid-based high-performance water reducing agent, and NS represents a naphthalenesulfonic acid-based high-performance water reducing agent.

Concrete mix In addition to the above concrete mix (sample 1 standard, sample 2 standard, sample 3 standard), assuming the fluctuation of surface water of fine aggregate (when surface water increases), each standard mix is further water was performed kneading mixed outer split each 15 kg / ^{m 3} and 30kg / ^{m 3.}
Example of concrete production method: Using a pan mixer, cement, fine aggregate, coarse aggregate, water, AE agent and polycarboxylic acid-based high-performance AE water reducing agent are charged all at once into the mixer for 2 minutes. After kneading, a naphthalene sulfonic acid high-performance water reducing agent was added to the mixer and kneaded for 1 minute.
Comparative Example: Using a pan-type mixer, cement, fine aggregate, coarse aggregate, water, AE agent and AE water reducing agent were all put into the mixer and mixed for 2 minutes.

Test method for concrete The kneaded concrete was poured into a 15 × 15 × 53 cm formwork, and compacted by applying vibrations at 6 points for 5 seconds with a rod-like vibrator.
2. Immediately after compaction, one side plate was slipped and removed.
3. The amount of subsidence (edge slump) and swelling near the center of the surface from which the mold was removed (position of 26.5 cm) were measured. In FIG. 1, as shown in the partially enlarged display of the side view, the edge slump is the change amount A in the vertical direction, and the bulge is the change amount B in the horizontal direction. Tables 2 and 3 show the measurement results (mm) and the evaluation results.

As shown in the above table, in the concrete produced by the production method of the present invention, including the case of adding water (assuming fluctuations in the surface water volume of fine aggregate), the occurrence of sagging and harassment after construction of the slip form method It turns out that it has suppressed. In addition, adhesion to the formwork of the concrete manufactured with the manufacturing method of this invention was not recognized.
On the other hand, in the concrete using the AE water reducing agent of the comparative example, it was found that when water was added (depending on the fluctuation of the surface water amount of the fine aggregate), sagging and harassment after construction of the slip foam method increased.

11 Construction surface 12 Slip form 20 Concrete

Claims (3)

Unit cement content is 250~680kg / ^{m 3,} water-cement ratio is 0.25 to 0.50, the horizontal self-propelled unit coarse aggregate bulk volume 0.60~0.85m ³ / ^{m 3} for slipform method A method for producing concrete, at least kneading cement, polycarboxylic acid-based water reducing agent, naphthalenesulfonic acid-based water reducing agent, aggregate, and kneaded water ,
Either one of polycarboxylic acid-based water reducing agent or naphthalene sulfonic acid-based water reducing agent is mixed with cement, aggregate, and kneaded water, and before placing on the slip foam formwork at the construction site, the other A method for producing concrete for a slip foam method, comprising adding a water reducing agent and kneading. Concrete containing a polycarboxylic acid-based water reducing agent is kneaded so that the concrete slump is 4.0 to 12.0 cm, and then a naphthalene sulfonic acid-based water reducing agent is added afterwards to add concrete slump to 2.0 to 6. The method for producing concrete for a slip foam method according to claim 1, wherein the concrete is 0 cm . A slip foam method using the slip foam concrete produced by the method according to claim 1.