JPH0534886Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention relates to a water-permeable sheet for concrete formwork that is attached to the concrete pouring side of the concrete formwork and excludes moisture and air from the concrete. .

(Conventional technology) Recently, with the aim of beautifying the concrete surface and improving the durability of the concrete surface, special sheet materials have been attached to formwork to effectively remove water and air separated from the concrete. has been
Various types of water-permeable sheets of this kind have been proposed.

However, all of these permeable sheets are made to remove air and excess water from the surface and to be easily demolded from the solidified concrete surface, and their interiors are designed to allow water to permeate easily. The water-permeable sheet is formed to enhance the drainage effect, and the back side is fixed with adhesive or staples to firmly secure it to the formwork, and it can be easily passed from the back side to the formwork to the outside of the water-permeable sheet. Constructed to allow drainage.

However, the above-mentioned water-permeable sheet is usually not used only once, but has to be used several times for economical reasons.

Therefore, a sheet material that can withstand multiple uses was investigated, and one of them was published in Japanese Patent Application Laid-Open No. 63-63858.
Examples are suggested.

As is clear from the description in the same publication, this sheet material has good mold releasability from poured concrete, and has a surface layer with many water-permeable and ventilation pores, and a back surface of this surface layer. water flow communicating with the pores;
It has a structure consisting of a base layer for maintaining gaps, which has many ventilation gaps in the thickness direction, and does not buckle or unbalance under the heavy pressure of poured concrete.

On the other hand, the present applicant has also been aiming to develop the above-mentioned sheet material using a nonwoven fabric as a base material, and previously proposed an improved nonwoven fabric for water absorption and drainage in Japanese Patent Application No. 63-282851.

This is made by integrating a fiber layer made of synthetic fibers and a synthetic fiber base fabric by needle punching, and then heat-processing only the surface of the fiber layer to make it a smooth layer without fluff, and Consisting of three layers: an intermediate layer with relatively low density consisting of the above-mentioned fiber layer and base fabric, and an adhesive backing layer formed by heat-treating the fibers exposed on the back side of the base fabric and integrating them with the base fabric surface. , the overall ventilation rate is 2.0 to 0.5 cc/cm ² /sec, the vertical hydraulic conductivity is 10 ^-2 to ^{10 -4} cm/sec, and the surface layer is small enough to not allow the solid content of the cement paste to permeate. It is a nonwoven fabric with pores or fiber gaps.

(Problem to be solved by the invention) However, when we conducted further practical tests on each of the sheet-like materials mentioned above, we found that they absorbed moisture from concrete, improved the finish of the concrete surface, and were excellent in releasing from the mold. Although it has various effects such as being able to be used several times, it has been found that the following problems arise after being fixed to a mold and used many times.

That is, when carrying out concrete construction by pasting the above-mentioned sheet-like material on the inner surface of a concrete formwork, the adhesive between the backing layer and the formwork is usually not adhesive on the entire surface, but at intervals to allow water to pass through. Because of the adhesion, water separated from the concrete C during concrete compaction flows into the intermediate layer 12 through the surface layer 11 as shown in FIG.
2 is adsorbed and discharged downward from below the intermediate layer 12 and through the adhesive gap l between the mold P and the backing layer 13 as shown by the arrow. The flow rate of water flowing down at this time is of course influenced by the air permeability and hydraulic conductivity of the sheet-like material as a whole, and is further determined by the pressure that the concrete exerts on the sheet-like material.

However, when the formwork is repeatedly used several times, the influence of the concrete pressure on the sheet material increases, and as the sheet material receives that pressure, the backing layer 2
The gap 1 between the mold and the formwork P gradually approaches a close contact state, and the water flowing down the gap 1 decreases, which impairs drainage efficiency and affects the finished concrete surface.

The present invention focuses on this actual situation and aims to prevent the deterioration of drainage efficiency due to the concrete pressure mentioned above.In particular, by forming small uneven wrinkles in the drainage layer, the water flow gap between the drainage layer and the formwork is reduced. The purpose is to maintain efficient drainage capacity even after repeated use several times, and to ensure a good finish on the concrete pouring surface by maintaining efficient drainage capacity over a long period of time.

(Means for Solving the Problems) That is, the feature of the water-permeable sheet of the present invention that satisfies the above-mentioned purpose is that it has at least a water-absorbing layer in contact with the concrete surface and a drainage layer for discharging absorbed water to the outside of the sheet. The drainage layer has a large number of uneven wrinkles over the entire surface so as to form a continuous drainage path to the outside of the sheet when it is attached to a formwork.

Although various types of water-permeable sheets can be considered, the present invention targets at least those selected from fiber sheets such as synthetic fiber non-woven fabrics or air-permeable and water-permeable sheets such as porous synthetic resin sheets. It is.

Of course, the water-permeable sheet of the present invention is not limited to the water-absorbing layer and the drainage layer, but also has ventilation and water permeability in the thickness direction between both layers to enhance the water-absorbing effect, and an intermediate layer for cushioning and reinforcement. Of course, it also includes interposing a water-permeable layer.

Then, the water absorption layer and the drainage layer, or the water absorption layer, the intermediate water permeable layer, and the drainage layer are joined and integrated, but the drainage layer is formed with relatively small uneven wrinkles of an appropriate size over the entire surface. , the water-permeable sheet is joined to the back side of the sheet and the formwork so that there is a drainage space, improving the drainage performance between them.

Various methods can be considered to generate small uneven wrinkles on the entire surface of the drainage layer, but the degree of thermal contraction of the water absorption layer and the drainage layer may be slightly different. It is most practical to generate wrinkles on the drainage layer side by heat shrinking and joining.

(Function) The water-permeable sheet of the present invention having the above-mentioned configuration is made by pasting a drainage layer with uneven wrinkles on the inner surface of a concrete formwork (panel) with an adhesive, etc., and then molding the water-permeable sheet with the water-absorbing layer side inside. Assemble and pour concrete.

The poured concrete slowly absorbs water through the many holes in the permeable sheet, and this absorbed water flows directly downward from the drainage layer, and then passes through the uneven wrinkles and flows into the formwork and the recesses in the drainage layer. The water is discharged downward through the continuous drainage passage formed in this way.

As mentioned above, the smooth surface layer provides a smooth finish on the concrete surface, and also makes it easy to remove from the mold, and even if the slag (dissolved cement) that adheres to the surface dries, it can be easily washed with water, etc. It is removable and can easily withstand repeated use several times.

During the above-mentioned drainage process, especially after repeated use several times, the drainage layer is gradually pressed down by the pressure of the concrete, and the gap between the layer and the concrete formwork gradually becomes clogged. However, the passage gap formed between the formwork and the creases in the drainage layer secures a drainage passage for a long time, and the drainage efficiency hardly decreases, helping to achieve a good finish on the concrete pouring surface. .

(Embodiments) Hereinafter, embodiments of the present invention will be described with further reference to the accompanying drawings.

The figures show an embodiment of the present invention. Figure 1 is a partially enlarged view of the permeable sheet viewed from the drainage layer side, and Figure 2 is the first
FIG. 3 is a partially enlarged sectional view showing the usage state of the same embodiment.

In each of these figures, 1 indicates a water absorption layer, 3 indicates a drainage layer, and the water absorption layer 1 is made of a sheet such as a needle-punched nonwoven fabric with a synthetic fiber base fabric, a dense synthetic fiber fabric, or a porous synthetic resin sheet.
On the other hand, the drainage layer 3 is similarly made of a sheet of synthetic fiber non-woven fabric, woven fabric, etc., or a porous synthetic resin sheet, and both are directly joined or fused together with a hot melt web sheet in between.

In the figure, the surface of the water-absorbing layer 1 is fused to form a smooth water-absorbing layer 2 that has good releasability to concrete.

In the drainage layer 3, a large number of small uneven wrinkles consisting of concave portions 4 and convex portions 5 are formed.

The shape of the uneven wrinkles 4 and 5 is determined by utilizing contraction in the width direction so that the protrusions 5 and recesses 4 of appropriate lengths are arranged in parallel in the longitudinal direction, and by using the contraction of the protrusions 5 and recesses 4 of appropriate sizes. There is a method that takes advantage of shrinkage in the length and width directions so that they are arranged randomly, but in either case, the water absorption layer 1 and the drainage layer 3 are integrated, and as shown in Figure 3, the water absorption layer 1 and the drainage layer 3 are It is important that the convex portions are joined with sufficient adhesion and peeling strength, and that the concave portions of the drainage layer 3 form a continuous space of the drainage passage 6 with the mold surface.

As a method for forming uneven wrinkles, various methods can be considered as described above, but the most common method is to make the water absorption layer 1 and the drainage layer 3 have different degrees of heat shrinkage, so that the water absorption layer 1 is different from the drainage layer 3. A method is used in which unevenness and wrinkles are generated at the same time as bonding by causing several percent more heat shrinkage.

In this way, when the uneven wrinkles are generated by thermal contraction, it can be performed during heating in the bonding process, and the process can be simplified. In this case, it is sufficient for the size of the uneven wrinkles to be less than mm in the width of the concave and convex portions, and 1 to 2 mm in height from the concave portions.

The water-permeable sheet of the present invention has the above-mentioned structure. Next, we will explain its usage condition.
Paste it on the concrete formwork P as shown in the figure,
It is used so that the water absorption layer 1 is on the concrete C pouring side. At this time, it is most convenient to use an adhesive for bonding to the formwork P.

Then, when concrete is poured into the formwork to which the water-permeable sheet is attached, only moisture in the mortar is absorbed from the water-absorbing layer 1 through its pores, and all cement particles except fine ones are blocked. If the flow velocity is too high here, the Senmeth particles will be absorbed into the water absorption layer 1.
It is easy for water to penetrate inward through the pores of the concrete, causing a decrease in the strength of the concrete surface. Therefore, the air flow rate of the entire permeable sheet should be kept below approximately 1.0 cm ² /sec, and the vertical permeability coefficient should be 10 ^-2 cm / sec. If the water is kept at a rate of ~10 ^-4 cm/sec, the absorbed water will pass through the drainage layer 3 and through the space of the drainage passage 6 formed by the recesses of the drainage layer 3 and the formwork surface, and will resist downward movement. It is drained without receiving water.

The drainage passage 6 between the recess 4 of the drainage layer 3 and the formwork P can sufficiently withstand the influence of concrete pressure and maintain drainage efficiency even if the influence of concrete pressure increases after the formwork is used several times. The drainage action can be continued sufficiently.

(Effects of the invention) As described above, the water-permeable sheet of the invention has a water absorption layer and a drainage layer, the drainage layer shrinks less than the water absorption layer, and a large number of continuous uneven wrinkles are formed over the entire surface. The water absorbed from the water absorption layer flows down continuously through the drainage passage formed between the uneven wrinkles of the drainage layer and the formwork.
This prevents the drainage passage between the sheet and the formwork from becoming blocked even after several uses, reducing drainage efficiency, and it can withstand concrete pressure even after several uses. It has the remarkable effect of eliminating the influence on the formwork joint surface and allowing sufficient drainage to continue downward through the formwork joint surface, that is, the joint space between the formwork and the drainage layer.

The invention according to claim 2 makes the water absorption layer and drainage layer of the water permeable sheet more specific.

In addition, the invention as claimed in claim 3 provides an intervening intermediate layer to further enhance the water absorption effect, and uses sheets with a difference in heat shrinkage for the water absorption layer and the drainage layer, so that they can be shrunk at the same time as bonding by heat treatment. It has the effect of simplifying the process.

[Brief explanation of the drawing]

Figure 1 is a partially enlarged view of the water-permeable sheet of the present invention viewed from the drainage layer side, Figure 2 is a sectional view taken along line A-A in Figure 1,
FIG. 3 is a partially enlarged sectional view showing the usage state of the same embodiment, and FIG. 4 is an explanatory diagram of the suction and drainage action. 1...middle layer, 2...water absorption layer, 3...drainage layer,
4... Concave portion, 5... Convex portion, 6... Drainage channel, C...
Concrete, P...formwork.

Claims (1)

[Claims for Utility Model Registration] 1. A sheet comprising at least two layers: a water absorption layer in contact with the concrete surface and a drainage layer that discharges absorbed water to the outside of the sheet, and the drainage layer forms a continuous drainage passage over its entire surface. A water-permeable sheet for concrete formwork, characterized by having a large number of uneven wrinkles. 2 The water absorption layer in contact with the concrete surface and the drainage layer that discharges the absorbed water to the outside of the sheet are composed of sheets selected from synthetic fiber sheets or synthetic resin sheets that have a difference in heat shrinkage, and the water absorption layer is made larger than the drainage layer. A water-permeable sheet for concrete formwork, which is characterized by being shrunk to generate a large number of uneven wrinkles that form drainage passages that are continuous over the entire surface of a drainage layer. 3. A water absorption layer made of a synthetic fiber sheet or synthetic resin sheet with high heat shrinkability and a drainage layer made of a synthetic fiber sheet or synthetic resin sheet with low heat shrinkability are interposed between an intermediate water permeable layer having cushioning properties in the thickness direction. It is characterized by the fact that by heat treatment, the drainage layer with small heat shrinkage and the water absorption layer with large heat shrinkage form uneven wrinkles that form continuous drainage passages over the entire surface. Water-permeable sheet for concrete formwork.