JP2600727B2 - Concrete casting formwork - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a concrete casting method capable of efficiently absorbing moisture generated from concrete at the time of casting concrete, and thus allowing concrete to be cast on a clean surface having no traces of water bubbles. Related to installation formwork.

2. Description of the Related Art Conventionally, in concrete casting, a formwork made of wooden plywood (plywood) or an iron frame has been used.
When casting concrete using these molds, in order to improve workability, more water than required for hydration is added to concrete, and the concrete is solidified with a vibrator.

In this case, when solidifying with a vibrator, excess moisture accumulates on the concrete surface, and at this time, air bubbles accumulate on the form surface. If the concrete is hardened in this state, traces of air bubbles and water bubbles remain on the surface, causing fine irregularities, so-called junkers, which causes a problem that the surface strength and smoothness of the concrete are reduced.

For this purpose, recently, for the purpose of actively absorbing the water present on the concrete casting surface or discharging the same to the outside so that no air bubbles or water bubbles remain on the concrete surface, for example, Japanese Patent Application Laid-Open No. As described in JP-A-151366, a water-absorbent cloth sheet or a nonwoven fabric is adhered to the surface of a mold, or fine small holes are formed in the mold, and excess water and air bubbles are discharged from these small holes. Something like that has been proposed.

Problems to be Solved by the Invention However, there is a risk that the water-absorbing cloth sheet or non-woven fabric attached to the surface of the form may absorb moisture prior to concrete placement, and if these absorb moisture, they are contained in concrete. Absorbing moisture that has been lost becomes ineffective.
On the other hand, in the case where a small hole is formed in a mold, the efficiency of discharging water from the small hole is not always efficient due to the surface tension of water, and a large number of through holes are formed in the mold. In addition, it takes considerable time and effort to provide such a large number of through-holes, especially when wooden plywood is used as a formwork material, since the strength of the plywood is weakened. Therefore, there is a problem that the thickness of the wooden plywood must be increased unnecessarily, and thus the handleability may be deteriorated due to an increase in the weight of the formwork.

The present invention has been made in view of the above circumstances, and it is possible to efficiently and reliably remove moisture generated from concrete at the time of placing concrete, so that water marks, fine irregularities (junka), etc. are formed on the surface of the concrete. An object of the present invention is to provide a concrete casting formwork that can be cast neatly without causing it to be produced, has good handleability, and can be used easily.

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, while ordinary water is neutral or acidic, it is used for hydration of concrete. Since the water content is alkaline, a water-absorbent sheet is provided on the surface of the concrete casting surface mainly composed of formwork, and an alkali-soluble water-impermeable coating layer is formed on the surface, so that the water-absorbent sheet is cast on concrete. Previously, the alkali-soluble coating layer on the surface of the water-absorbent sheet is dissolved by the moisture that has accumulated on the concrete surface during concrete placement without absorbing moisture through the coating before the concrete placement. It can effectively absorb the water that accumulates, and therefore efficiently and reliably remove the water that causes water marks and jumpers on the concrete surface. They have found that they can be removed and have completed the present invention.

Therefore, according to the present invention, a water-absorbent sheet is fixed to a concrete casting surface mainly of a formwork, concrete is poured on the water-absorbent sheet, and excess water generated from concrete at the time of concrete placing is removed by the water-absorbent sheet. In a concrete casting formwork configured to absorb, a hardly soluble or insoluble in a neutral and acidic region on the concrete casting side surface of the water-absorbent sheet, and an alkali-soluble water-impermeable coating layer is formed. , And concrete is cast on the coating layer.

Function The formwork of the present invention is provided with a water-absorbent sheet on the concrete casting surface mainly of the formwork as described above, and further having an alkali-soluble film layer formed on the surface thereof. However, due to the alkali-soluble coating layer formed on the surface of the water-absorbent sheet, the water-absorbent sheet does not absorb neutral or acidic moisture before concrete is poured, and therefore, before the concrete is poured. It is possible to reliably prevent the water-absorbent sheet from being insufficiently absorbed at the time of placing concrete due to the absorption of moisture. Moreover, the above-mentioned film is dissolved for the first time by the alkaline moisture generated from the concrete when the concrete is poured, whereby the excess water from the concrete can be efficiently and reliably removed, and water marks and junka are formed on the concrete casting surface. Is reliably prevented, so that the concrete surface can be cast neatly. Moreover, according to the mold of the present invention, only the absorbent sheet having an alkali-soluble film formed on its surface is attached to the mold main body, and no through-hole is formed in the mold main body. It is easy to manufacture, and has sufficient strength even if the main body of the form is not formed thick, and it is not necessary to form the main body of the form in this way, so that it is excellent in handleability. is there.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

The drawings show a concrete casting mold 1 according to an embodiment of the present invention, and the mold 1 is a concrete casting side of a mold main body 2 made of metal, wood or other material. The water-absorbent sheet 3 is fixed to the surface by an appropriate method, and an alkali-soluble coating layer 4 is formed on the surface of the water-absorbent sheet 3 on the concrete casting side.

Here, as the water-absorbing sheet 3 constituting the mold 1,
There is no particular limitation, as long as it has good water absorbency. In particular, fibers such as rayon, polypropylene, polyethylene terephthalate, nylon, vinylon, cotton, wool, acrylic, or a blend of these fibers are preferred because of their high water absorbency. Water-absorbing vinyl acetate-acrylic acid copolymer, starch-acrylic acid graft copolymer, starch-acrylonitrile graft copolymer, polyvinyl alcohol-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, polyacryl Polymer gels such as acid-based polymers (for example, Sumika Gel (Sumitomo Chemical Industries, Ltd.)
)) Or a non-woven fabric made of a water-absorbing resin (for example, Lanseal (manufactured by Kanebo KK)) or the like.

Next, the alkali-soluble coating layer 4 formed on the concrete casting side surface of the water-absorbent sheet 3 is water-impermeable and hardly soluble or insoluble in neutral and acidic regions, and is resistant to liquids in alkaline regions. It is not particularly limited as long as it can be easily melted. For example, natural resins include gum rosin and shellac, and synthetic resins include alkyd resins.

When casting concrete using this formwork 1,
Concrete is cast on the alkali-soluble coating layer 4. Thereby, the alkaline moisture generated from the concrete dissolves the alkali-soluble coating layer 4 formed on the surface of the water-absorbent sheet 3 and is absorbed by the water-absorbent sheet 3. In this case, since the water-absorbent sheet 3 has the alkali-soluble coating layer 4 formed on its surface, it does not absorb acidic or neutral moisture before placing concrete, and the water-absorbent sheet 3 originally has The performance is maintained as it is, and it shows good absorbency. Therefore, according to the form 1, it is possible to efficiently and reliably absorb and remove the water generated from the concrete, so that the water mark, fine irregularities, so-called jungle, which are caused by the water bubbles, are generated on the concrete casting surface. And the concrete surface can be cast neatly.

In addition, in the mold 1, the water absorbing sheet 3 having the alkali-soluble film 4 formed on the surface of the concrete casting surface of the mold main body 2 is fixed by an appropriate method, or After the sheet 3 is fixed, the alkali-soluble coating layer 4 is formed, so that it can be easily manufactured. Further, since the through-hole is not formed in the mold main body 2, the mold main body 2 is formed thick. Even if it does not have sufficient strength, it can be used easily without a decrease in handleability due to an increase in the weight of the mold 1.

The concrete casting formwork of the present invention is not limited to the above-described embodiment, and its configuration may be variously changed without departing from the gist of the present invention.

Effects of the Invention As described above, according to the concrete casting formwork of the present invention, the water-absorbent sheet is formed before the concrete is cast by forming the alkali-soluble coating layer on the surface of the concrete-casting surface of the water-absorbent sheet. Absorbs neutral or acidic moisture, effectively preventing insufficient absorption of the water-absorbent sheet during concrete placement,
Therefore, it is possible to efficiently and surely absorb and remove the moisture generated from concrete at the time of placing concrete.
For this reason, it is possible to cast concrete neatly without causing water marks, junkers, etc. on the surface of the concrete. Further, according to the mold of the present invention, an alkali-soluble film was formed on the surface of the mold mainly. Since it only sticks the water-absorbent sheet and does not form a through hole in the main body of the formwork, it is easier to manufacture the formwork and has sufficient strength without forming the main body of the formwork thick. Furthermore, since the mold main body does not have to be formed thick as described above, the handleability is excellent.

[Brief description of the drawings]

The drawings are sectional views showing one embodiment according to the present invention. 1 ... mold, 2 ... mold main body, 3 ... water-absorbent sheet, 4
... An alkali-soluble film layer.

Claims (2)

(57) [Claims] 1. A water-absorbent sheet is fixed to a concrete casting surface mainly composed of a formwork, concrete is poured on the water-absorbent sheet, and excess water generated from the concrete when the concrete is poured is absorbed by the water-absorbent sheet. In the concrete casting formwork configured to be, hardly soluble or insoluble in neutral and acidic regions on the concrete casting side surface of the water-absorbent sheet, forming an alkali-soluble water-impermeable film layer, A concrete casting formwork, wherein concrete is cast on the coating layer. 2. The concrete casting mold according to claim 1, wherein the alkali-soluble water-impermeable coating layer is a gum rosin, shellac or alkyd resin.