JP6525326B2 - Slip form method - Google Patents

Description

The present invention relates mainly to a slip foam method used in the civil engineering / building industry and the like.

The slip form construction method is a method suitable for construction of a concrete structure having the same cross-sectional shape with a long dimension such as road related facilities such as a road median, a circular channel, side gutters, pipe winding, standing walls, etc. Using a self-propelled construction machine equipped with a compaction device and a shaping device, the long-size concrete is compacted into a predetermined same cross-sectional shape and slipped while molding, and the concrete structure is continuously formed. It is a construction method of construction.

The concrete used in the slip form construction method maintains the fluidity necessary for production, transportation and construction, and allows the cast concrete to slip by its own weight so that the formwork can be quickly slipped after vibration forming. Are required to have resistance to deformation.

Conventionally, as concrete used in the slip foam construction method, small slump hard concrete is used in order to prevent the generation of a warp due to its own weight. Since such hard-mixing concrete has extremely poor fluidity, there are problems such as blockage with a hopper at the time of shipment and difficulty in discharging when arriving at a construction site when transporting by agitator vehicles, and so dump truck It is supposed to be transportation. However, even dump trucks have the problem that there is a risk of quality deterioration during transportation.

For this reason, a method is proposed in which a cement additive in which a water-reducing agent and a natural polysaccharide and / or a water-soluble acrylic polymer are blended in a specific ratio is added in the field to concrete in which fluidity has been secured. (Patent Document 1). However, in the method of adding an organic thickener or viscosity modifier in the field, the viscosity of the concrete becomes high and the workability decreases, and the concrete is easily attached to the formwork, and the finish is poor and the appearance is impaired. There was a problem. In addition, when the surface water amount of aggregate increases, there is a problem that the sagging and the harami become large.

Japanese Patent Application Publication No. 08-109053

 So, in this invention, generation | occurrence | production of a sagging or harami can be suppressed after slip foam construction method construction, and the slip foam construction method which can manufacture the structure which is excellent in an aesthetics, without adhering to a formwork is provided.

The present inventors completed the present invention as a result of intensive studies to achieve the above object. That is, the present invention provides the following [1] and [2].

[1] A concrete with 2.0 to 6.0 cm of slump formed by kneading at least cement, a water reducing agent, an aggregate, and kneading water is placed in a slip foam form and after compaction, or the slip The present invention provides a slip foam method characterized in that a liquid quickening agent is brought into contact with the surface of the concrete molding after moving a foam form.
[2] The slip foam construction method according to claim 1, wherein the contact amount of the liquid accelerator is 50 to 200 g / m ² .

FIG. 1 shows a conceptual view of the slip foam method. It is a method of forming with the slip formwork 12 while placing concrete 20 on the construction surface 11, and shows a front view, a plan view and a side view thereof. The side view represents the molded concrete which is self-supporting, past the slip formwork. In fact, the free standing is not 100%, and an edge slump (a change amount A in the vertical direction) and a bulge (a change amount B in the horizontal direction) are generated. Here, the slip foam form is a form attached to a molding machine (mold). In the present invention, "parts" and "%" are units shown on a mass basis unless otherwise specified. Moreover, the concrete in the present invention includes mortar.

 In the slip foam method of the present invention, at least a concrete having 2.0 to 6.0 cm of slump formed by kneading cement, a water reducing agent, an aggregate, and kneading water is cast into a slip foam form and compacted. After or after moving the slip foam mold, the surface of the concrete compact is contacted with a liquid quick-setting agent. In addition, bringing a liquid quickening agent into contact with the surface of the concrete molded body is an operation such as spraying, spraying, applying, or dripping the liquid quickening agent on the surface of the concrete molded body. In the present invention, it is preferable to spray or spray the liquid quick-set on the surface of the concrete molding in view of ease of operation and the like.

As the liquid accelerator, commercially available liquid accelerators (for example, “Sigunit L53AF” manufactured by Nippon Sika Co., Ltd., “Master Lock SA 161” manufactured by BASF Japan, etc.) can be used. The liquid accelerator does not have to be transparent and may contain a suspension, but is a liquid which does not contain the powder of the cement composition, and is fresh at the time of construction without being mixed and kneaded with the cement material. It is used by spraying directly on the concrete molding surface.

Contact of liquid quick-setting admixture, from the viewpoint of cost and slip-form method after application of sagging or skirt steak for the generation control is preferably a concrete molded body 1 m ² per 50 to 250 g (more preferably 70～200G) .
The contact of the liquid accelerator can be carried out using a commercially available spray device or the like.

The contact of the liquid accelerator is within 15 minutes after moving the slip foam form immediately after compacting the concrete (more preferably within 10 minutes after moving the slip foam form, particularly preferably moving the slip foam form) Preferably within 5 minutes). The contact of the liquid quick-setting agent may be performed by attaching a spray device or the like to a compacting tool, a surface finish tool, or a slip mold and spraying may be performed, or separately using a spray device or the like.

Usually, the liquid accelerator is often mixed with the cement material immediately before the construction, mixed and sprayed, but if mixed with the cement material, the fluidity is impaired at the time of construction, making the construction difficult. Moreover, the spray which mixed solids, such as powder, spoils the beauty of the surface. In addition, when a quick-setting agent containing a powder such as calcium aluminate or alkali aluminate is used as the quick-setting agent, the surface on which the concrete is applied may be roughened to impair the appearance. In addition, due to the powder scattering, the construction environment may deteriorate and the construction itself may become difficult.

In addition, the concrete for slip form construction method manufactured by the method of the present invention has a slump of 2.0 or more as described above from the viewpoint of suppressing the workability at the time of construction of the slip form construction method and the occurrence of sagging and flaking after construction. It is 6.0 cm, more preferably 2.5 to 5.5 cm, and the concrete has an air content of 3.0 to 7.0% by volume, more preferably 3.5 from the viewpoint of durability and the like. ~ 6.5 vol%.

The cement used in the present invention is any of various Portland cements such as normal strength, early strength, super early strength, low heat and moderate heat, and various mixed cements obtained by mixing blast furnace slag, fly ash or silica with these portland cements, limestone The filler cement which mixed the powder, the blast furnace slow-cooling slag fine powder, etc., and a common ecocement are mentioned, and 1 or 2 types of these can be used.

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

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

As a water reducing agent, a water reducing agent, an AE water reducing agent, a high performance water reducing agent, or a high performance AE water reducing agent such as lignin type, naphthalene sulfonic acid type, melamine type or polycarboxylic acid type can be used. In the present invention, it is preferable to use an AE water reducing agent from the viewpoint of cost and suppression of generation of sagging and cracking after construction of the slip foam construction method. The amount of water reducing agent added is preferably 0.1 to 0.5% by mass (more preferably 0.15 to 0.4% by mass) based on cement.

 In the present invention, in addition to the above materials, depending on the case, expanding agents, quick-hardening materials, thickeners, shrinkage reducing agents, polymers, clay minerals such as bentonite, ground granulated blast furnace slag powder, limestone fine powder, fly ash And silica fume, and one or two or more of admixture materials such as regenerated fine powder and fibers generated when producing regenerated aggregate, or fibers and the like in a range not to substantially inhibit the object of the present invention. It is possible.

The concrete for the slip foam construction 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 from the viewpoint of suppressing the occurrence of dripping and flaking after construction of the slip foam construction method. 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.}

The method of kneading the concrete is not limited, and for example, all the materials can be collectively introduced into the mixer and kneaded. Moreover, a kneading apparatus is not limited, For example, an omnimixer, a pan-type mixer, a biaxial mixer etc. can be used. In addition, the said concrete may knead | mix in a green concrete plant, and may knead | mix it at a construction site.

In the slip foam method of the present invention, it is possible to suppress the occurrence of sagging or flaking after the slip foam method construction. In addition, it is possible to manufacture a structure excellent in aesthetics without adhering to the mold.

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

As the standard formulation, as shown in Table 1, the following materials and blending conditions were used.
(1) Materials used Cement (C): Ordinary portland cement (made by Pacific Cement Co., Ltd.)
Fine aggregate (S): Mountain sand (from Kakegawa City, Shizuoka Prefecture, surface dry density 2.57 g / cm ³ )
Coarse aggregate (G): Sandstone crushed stone 2005 (from Sakuragawa City, Ibaraki Prefecture, surface dry density 2.65 g / cm ³ , actual volume 59.6%)
Water (W): Tap water chemical admixture: AE water reducing agent ("Master pozzolith No. 70" manufactured by BASF Japan Ltd.)
AE agent ("Master air 202" manufactured by BASF Japan Ltd.)
Liquid accelerator: "Sigunit L53 AF" manufactured by Nippon Sika

(2) Compounding conditions and concrete properties Unit water volume ..... 140 kg / m ³
Water cement ratio ..... 42%
Unit coarse aggregate bulk volume ··· 0.73 m ³ / m ³
Slump ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 4.0 ± 1.5 cm
Air content ........... 5.0 ± 1.5 volume%
And set.

Compounding of concrete In addition to the above-mentioned concrete standard compounding, in consideration of fluctuation of surface water of fine aggregate (when surface water became large), mixing was carried out with the composition which mixed water 15 kg / m ³ outside split .

Method of producing concrete Using a pan type mixer, cement, fine aggregate, coarse aggregate, water, AE agent and AE water reducing agent were collectively introduced into the mixer and mixed for 2 minutes. The addition amount of the AE agent was C × 0.010%.

Test method of concrete 1. The mixed concrete is poured into a 15 × 15 × 53 cm mold and vibrated at 6 points for 5 seconds with a rod-shaped vibrator to compact it.
2. Immediately after compaction, slide out the side plate of one side and remove it.
3. The side plate is removed, and the exposed molded article is sprayed with the liquid quickener in the amount shown in Table 2 below. In addition, spraying was performed within 3 minutes after exposure of a molded object.
4. The amount of settlement (edge slump) and bulge near the center of the mold-removed surface (at 26.5 cm) was measured.
Table 2 shows the result in the case of the standard combination of a unit water amount of 140 kg / m ³ , and Table 3 shows the result in the case where water is additionally mixed at 15 kg / m ³ .

As shown in Tables 2 and 3 above, in the slip foam construction method of the present invention, including the case where water is added (assuming fluctuation of surface water amount of aggregate), the occurrence of dripping and harami after construction of slip foam construction method is suppressed I know that I can do it. 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 case where the liquid quick-setting agent is not sprayed (0 g / m ² ), it is understood that the sag (edge slump value) and the curling (bulge value) after the slip foam construction method are large.

11 construction surface 12 slip form form 20 concrete

Claims (2)

  A concrete with 2.0 to 6.0 cm of slump formed by kneading at least cement, water reducing agent, aggregate, and kneading water is cast into a slip foam form and after compaction, or the slip foam form A slip foam method characterized in that a liquid quick-setting agent is brought into contact with the surface of the concrete molding after moving. ^2. The slip foam method according to claim 1, wherein the contact amount of the liquid accelerator is 50 to 200 g / m < ² >.