JPH03219919A - Composite water permeable sheet - Google Patents

Abstract

PURPOSE:To prevent drainage efficiency from lowering and keep drainage capacity even after repeated use by a method wherein fiber layer made of synthetic resin and synthetic resin base fabric are integrated with each other by needle punching and, after that, the surface of the fiber layer is hot-melted. CONSTITUTION:Fiber layer 1 and synthetic fiber base fabric 2 are integrated with each other by needle punching. By thermally processing the surface of the fiber layer, its surface fibers are melted so as to produce surface layer 4, which is smoothed locally to near filmy state, and, on the other hand, the fibers projected to the rear side is integrated with the base fabric by heat treatment so as to produce the rear layer in order to obtain the sheet concerned. Synthetic resin sheet 3 having small recessed parts 3a and projected parts 3b, both of which face to the rear layer 2 and form continuous passage gaps, is joined to the rear layer 2 under the condition that the crest surface of the projected part 3b acts as the joint surface to the rear layer 2. Accordingly, continuous passage gap is produced between the rear layer 2 and the bottom of the recessed part 3a of the resin sheet 3.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a composite type water-permeable sheet, particularly the above-mentioned composite type water-permeable sheet having both water absorption and drainage performance, which is used for pasting on formwork used in concrete construction. Regarding.

(Prior Art) Formwork used when constructing concrete structures is used to aestheticize the concrete surface, that is, to prevent water pockmarks from occurring on the surface that the formwork touches. It affects the removal of air bubbles, improvement of the durability of the concrete surface, and densification of the concrete composition by removing excess water. Conventionally, plywood panels, steel panels (
Metal foam) was used for boat fishing, but recently,
This has been used as an actual construction method in development and construction, and various attempts have been made to attach special materials to the formwork to remove pockmarks in the concrete in contact with the formwork surface.

For example, in Japanese Patent Publication No. 57-42782, a hydrophilic sheet is pasted on the surface of the mold to improve mold release and increase the number of times it can be used. According to the publication, porous material is pasted on the inner surface of the formwork, holes are made in the weir plate and porous material is pasted on top of the holes to release air bubbles from the concrete to the outside, and surplus water is drained from the holes. It flows downward through the

Furthermore, in Japanese Utility Model Application Publication No. 62-9642, a double structure is used: an outer layer structure with a dense structure that allows moisture and air to pass through but does not allow solids such as cement particles to pass through, and an inner layer structure that has a coarse Mi weave density. A formwork has been proposed that includes a sheet and a synthetic resin plate having a group of protrusions that allow air and water coming out through the sheet to communicate with the protrusion gaps.

More recently, a special feature on literature “Building materials”, voI-44+
N13, (1988) etc., it is effective to ``quickly absorb excess water, reach a certain amount in 30 minutes, and retain the absorbed water without releasing it'', so we expect super absorbent polymers to be effective. The method of attaching a specially processed thick long fiber non-woven fabric to a formwork and relying on the water-absorbing power of the fibers themselves was introduced as a water-absorbing formwork. A formwork to which a nonwoven fabric of about 0.4 tm in thickness is pasted made of superabsorbent fibers is described.

On the other hand, as permeable formwork, conventional methods have been to provide fine drainage holes in the formwork, or to provide a water collection net or a water collection synthetic fiber resin plate between the formwork and water absorbing fabric, but the above-mentioned document ( In the "Building Materials" special feature), when excess water and air are drained from the fine drainage holes provided in the formwork, the performance required for the fiber material attached to this is to allow only the water and air separated from the concrete to pass through. It is stated that a filtering effect is required to keep the cement particles within the mold, and that it is preferable to use a special polyester fabric with high air permeability and water permeability.

However, there are currently no fiber materials such as nonwoven fabric sheets used for drainage and water-permeable formwork as described above that are fully satisfactory and have not yet been widely used in industry.

This is thought to be because conventional fibrous materials such as nonwoven fabrics are not smoothed, resulting in fluff, which increases adhesion to concrete during concrete placement and can only be used once.

Therefore, we focused on the above-mentioned actual situation, and created a surface layer that has good mold releasability from poured concrete and has a large number of water permeable 2 ventilation pores as a suitable water permeable 9 air permeable sheet material for concrete panels. A water passage is provided on the back side of the surface layer and communicates with the pores of the surface layer.

A sheet-like material comprising a base layer for maintaining gaps that has a large number of ventilation gaps in the thickness direction and does not buckle or unbalance under the heavy pressure of poured concrete has been proposed (see Japanese Patent Laid-Open No. 63-63858), and the present applicant Patent application No. 63-28285
In Publication No. 1, we proposed an improved nonwoven fabric for water absorption and drainage.

This is made by integrating a fiber layer made of synthetic fibers and a synthetic fiber base fabric by needle punching, and then thermally processing only the surface of the fiber layer to make it a smooth layer without fluff, and the following fiber layer. It consists of three layers: a relatively low-density middle layer made of base fabric, and an adhesive backing layer made by heat-treating the fibers exposed on the back side of the base fabric and integrating them with the base fabric surface. Air flow rate is 2.0 to 0.5 cc/cJ/
sec, vertical hydraulic conductivity is 10-'' ~ 10-'
crn/sec, and the surface layer portion is a nonwoven fabric having small pores or fiber gaps that do not allow the solid content of the cement paste to pass through.

(Problems to be Solved by the Invention) However, each of the above-mentioned sheet-like products absorbs water from concrete when used, improves the finish of the concrete surface, and also has good properties such that it does not easily release from the mold and can be used several times. Although it has various effects such as being possible, it has been found that there are the following problems.

In other words, when carrying out concrete construction by attaching a sheet-like material such as the one described above to the inner surface of a concrete formwork, the bonding between the backing layer and the formwork is usually not done by full-surface adhesion, but by leaving a gap to allow water to pass through. Since the water separated from the concrete during concrete compaction flows into the middle layer (5) through the surface layer (4) as shown in Figure 4,
The intermediate layer (5) is adsorbed and the adhesive gap (1) between the intermediate layer (5) from below and the formwork (P) and the backing layer (2) as shown by the arrow.
) and is discharged downward. 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, as it is used several times, the influence of concrete pressure on the sheet material increases, and as a result, the sheet material receives the pressure and the gap between the backing layer (2) and the formwork (P) ( f) The condition gradually approaches a close contact state, and the water flowing down through the gap (1) decreases, resulting in poor drainage efficiency and affecting the finished concrete surface.

The present invention has focused on such a situation, and aims to prevent the deterioration of drainage efficiency due to the above-mentioned concrete pressure.In particular, by using a resin plate with small irregularities, the gap between the back layer of the sheet material and the formwork is improved. Ensures water flow gap for a long time,
The purpose is to maintain drainage ability even after repeated use several times, and to provide a good finish on the concrete pouring surface.

(Means for Solving the Problems) That is, the features of the water-permeable sheet of the present invention that satisfies the above-mentioned objects include a fibrous layer of synthetic fibers and a base fabric of synthetic fibers, such as the nonwoven fabric for water absorption and drainage proposed by the applicant. are integrated by needle bunching, and the fiber layer surface is thermally melted to form a smooth porous surface having air permeable pores, and air permeable air pores communicating with the pores. The base material is a nonwoven fabric having a three-layer structure of an intermediate fiber layer with a cushioning function in the thickness direction and a reinforcing material backing layer having a base fabric with good water permeability. It has a structure in which synthetic resin plates having a large number of small irregularities forming continuous passage gaps are joined together with the top surfaces of the convex portions serving as joint surfaces.

The nonwoven fabric used in the present invention is generally the nonwoven fabric for water absorption and drainage proposed in the aforementioned Japanese Patent Application No. 63-282851. However, as long as the purpose is not deviated from, it is also possible to use a nonwoven fabric with the same effect. In this case, it is important that any nonwoven fabric has a three-layer structure: a smooth porous surface layer, an intermediate layer having a cushioning function, and a back layer having a base fabric.

The smooth surface layer of the nonwoven fabric can be obtained by suitably heat-treating only the surface of the fiber layer according to known means.

It is necessary for this surface layer to have a large number of pores that are permeable to air and water for drainage, and it is particularly important that the water be drained slowly. Therefore, the large number of pores formed in this surface layer are selected to have a size that allows only the moisture of the poured concrete to pass through, that is, a size that blocks all but the smallest cement particles (agglomerates). and increase the overall airflow rate to 2.0 to 0.5 cc/crA/se.
c preferably 1.0~0゜5 cc/cl/s
e (, vertical hydraulic conductivity is 10-''~10-' cm
/sec preferably 10-2 to 10-3 cm/sec
It is desirable to suppress it to about c.

On the other hand, the synthetic resin plate having small irregularities may have any shape such as groove, round, square, or rhombus.
As mentioned above, when the top surface of the convex portion of the small unevenness is used as the bonding surface and is bonded to the backing layer, it is necessary at least that the passage between the convex portions be in a shape that forms a continuous drainage passage, and At the same time, it is also desirable that the protrusions toward the base fabric joining surface do not protrude to the surface side and leave no traces on the concrete surface, and that they do not impede the adhesion of the nonwoven fabric to the surface of the concrete formwork.

Usually, commercially available synthetic resin plates are used.

(Function) The composite water-permeable sheet of the present invention having the above-described structure is attached to the inner surface of a concrete formwork (panel) via the top surface of the convex portion of the resin plate with an adhesive or the like, and the surface side of the water-permeable sheet is Set the mold inside and pour concrete.

The poured concrete slowly absorbs water through the many holes in the nonwoven fabric surface layer of the water-permeable sheet, and this absorbed water flows directly downward from the intermediate fiber layer and further passes through the base fabric backing layer to the backing layer. It is discharged downward through a continuous drainage passage formed by the concave portion of the resin plate.

As mentioned above, the smooth surface layer makes the finish of the concrete surface smooth, and it also makes it easier to release the mold, and prevents slag (dissolved cement) from adhering to the surface.
Even if it dries, it can be easily removed by washing with water, and it can easily withstand repeated use several times.

During the above-mentioned drainage, the nonwoven fabric base material is gradually pressed by the pressure of the concrete, especially after repeated use several times, and the space between the backing layer and the concrete formwork gradually becomes clogged. However, the passage gap formed between the bottom of the concave part of the resin plate and the back layer of the nonwoven fabric base material maintains a drainage passage for a long time without being crushed due to the shape retention of the resin plate to a certain extent, and the drainage efficiency is almost reduced. Helps achieve a good finish on the concrete pouring surface without causing any damage. Moreover, since the adhesive to the concrete formwork is made by the resin plate, the trouble of creating striped adhesion in consideration of water flow gaps is eliminated, and the water-permeable sheet can be easily attached to the formwork.

(Example) The present invention will be described in detail below with further reference to the accompanying drawings.

FIG. 1 is a sectional view showing an example of the composite water-permeable sheet according to the present invention in use, in which (1) is a fiber layer made of synthetic fibers, and (2) is a backing having a synthetic fiber base fabric with good water permeability. The layers (11, (21) are integrally formed by needle punching, and the surface of the fiber layer (1) is fused by heat treatment to form a smooth surface layer (4). As a matter of course, the surface layer (4) has pores for passing water separated from the concrete (C) filled into the formwork (P) throughout the solid cement paste. It is sized to prevent water from passing through.

Further, (5) is an intermediate layer (5) which has a cushioning function and is mainly made of fibers following the surface layer (4), and this also communicates with the water-permeable pores of the surface layer (4) to form capillary tubes. The back layer (2), which is provided with voids that absorb water by the phenomenon and has the base fabric on the back side thereof, is usually needle-punched only from the front side and intertwined together to form a three-layer structure, Small irregularities (3a) facing this backing layer (2) and forming a continuous passage gap, which is the essential part of the present invention;
(3b) The synthetic resin plate (3) has its unevenness (3b)
The top surface is bonded to the back layer (2) as a bonding surface. Therefore, a continuous passage gap is formed between the backing layer (2) and the bottom surface of the recess (3a) of the resin plate (3), as more clearly seen in FIGS. 2 and 3.

Various types of fibers such as nylon, polyester, and polypropylene fibers can be used as the synthetic fibers forming the constituent fiber layer (1), but the most practical ones include a layer of fine denier short fibers of polypropylene and a polypropylene flat yarn. A combination with a woven base fabric can be mentioned. In this case, the staple fibers may be ordinary polypropylene fibers or fibers with a low melting point, such as a core made of ordinary polypropylene and a sheath made of low melting polyester or polypropylene, each of which has its own thermal processing method. By performing the steps accordingly, the desired structure can be obtained.

Therefore, when creating a nonwoven fabric having a three-layer structure, the fiber layer (1) and the synthetic fiber base fabric (2) are integrated by needle punching, and then the surface of the fiber layer is thermally processed. The surface fibers are melted and partially smoothed to a state similar to a film to form the surface layer (4),
On the other hand, it can be obtained by heat-treating the fibers exposed on the back surface and integrating them with the base fabric to form a back layer having the base fabric.

In this case, heat processing of the surface is carried out using processing means such as rubbing on a hot plate or infrared heating, and is carried out by heat processing for several seconds to several tens of seconds at a temperature of approximately 200°C. Generally, the heat treatment on the back side is sufficient if it is at the level of a burnt process and is integrated with the base fabric without peeling.

Note that the three-layer structure nonwoven fabric base material usually has a basis weight of 300.
~800g/rf, thickness around 1 Tsuru, for concrete formwork, ventilation rate 2.0~0.5 cc/crl/se
c, preferably 1.0-0.5 cc/cni/se
c, vertical hydraulic conductivity is 10-” to 10-’am/sec,
Preferably 10-” to 10-” cm/se
Preferably, it has a value of c.

Of course, this value is not critical, but our experiments have shown that it is extremely effective to have a value within the above range from the viewpoint of water absorption rate and the risk of transporting cement particles.

On the other hand, the synthetic resin plate (3) having small irregularities may have any convex shape on its entire surface, regardless of its shape, such as grooves, cylindrical protrusions, square protrusions, diamond-shaped protrusions, etc. However, at least when viewed as a whole, the convex part has a shape that allows drainage to flow from top to bottom, and the base fabric (2) and formwork (P)
It is important that the convex portion protrudes from the surface of Table N (4) and does not leave any marks on the concrete surface. It is also desirable to make the tip of the convex portion flat or provide a rough surface so that it can be sufficiently bonded to the base fabric (2).

In the case of a veneer-type water-permeable sheet, the shape of the unevenness is composed of vertical grooves (3c) and convexities (3d), as shown in Figure 2 (() and (II)). However, in the case of roll-shaped water-permeable sheets (when transported rolled), the above-mentioned sheet is difficult to wind, so as shown in Figures 3 (a) to (c), It is preferable that the small protrusions (3e) of each shape are arranged randomly or regularly, especially as shown in FIG.

In the case shown in FIG. 3, it is desirable that not only the top of the protrusion but also the outside of the valley bottom (the part that contacts the form) be flat for adhesion. Also, when pouring concrete,
If these protrusions remain on the concrete surface from the surface layer of the nonwoven fabric due to lateral pressure, it will be a disadvantage, so the number of protrusions should be increased.
It is better to make the size of each piece small, and furthermore, it is preferable that the groove width and the diameter of the protrusion be less than a few U, and the height of the protrusion be about a few cranes.

When the water-permeable sheet of the present invention described above is used, it is attached to a concrete formwork (P) as shown in Figure 1, and the surface layer (
4) is used so that it is on the concrete (C) pouring side, but for bonding to the formwork (P), it is most convenient to use an adhesive with a release paper attached.

When concrete is poured into the formwork to which the water-permeable sheet is attached, only the moisture in the mortar is absorbed from the surface layer (4) through its pores, and all but the smallest cement particles are blocked. . If the flow rate is too high, Cenmet particles will easily penetrate into the middle layer (5) from the pores of the surface layer (4), or cause a decrease in the strength of the concrete surface. below about 1.0 cd/see, with a vertical hydraulic conductivity of 10-”a
m/sec to 10-'cm/secC, the absorbed water flows through the base fabric to the resin plate, passes through the space formed by the concave part of the resin plate and the base fabric, and flows downward. The water is drained without any resistance.

Next, specific examples of the water-permeable sheet of the present invention will be described.

(Example 1) As synthetic fibers, polypropylene fibers were used for both the fiber layer and the base fabric, the fiber layer was 200 to 400 g/%, the base fabric was a flat fabric, and both were integrated by needle punching.
A non-woven fabric was created.

Then, the surface of the fiber layer of the nonwoven fabric was heated and pressed with a thermal calendar roller to melt and compress it, thereby forming a smooth surface layer. On the other hand, a synthetic resin plate having vertical groove-shaped protrusions was prepared by pressing a polyethylene plate, and the grooves were 2u in width and 2fl in height. Then, both of the above were adhered to the base fabric side of the nonwoven fabric using the top surface of the protrusion as the adhesive surface to form a water-permeable sheet.

(Example 2) Next, a 2 to 15 denier blended polypropylene fiber was used as the fiber layer, and a polypropylene flat thread fabric was used as the base fabric.
A needle-punched nonwoven fabric with a weight of 0 g/rrr was prepared. Then, the surface fibers on the nonwoven fabric side are heat-fused to form a smooth porous surface layer, followed by an intermediate layer of fibers with a high porosity that has a cushioning function, and a base fabric with high water permeability as a reinforcing material. A nonwoven fabric having a layered structure with a thickness of 1 fl was prepared. This non-woven fabric has an air permeability of 0.5 c as a whole.
c/c4/sec.

Vertical hydraulic conductivity is 2 x 10-'cm/sec, water droplet absorption rate is 10 minutes (JIS-L-1096-6, 26,
It had a slow water absorption rate (by the dropping method). Next, we made 4 cranes in diameter for this non-woven fabric.

A polyethylene sheet (Fig. 3 (a)) in which cylindrical protrusions with a height of 2.5B are arranged in a staggered manner with a gap of 21 m is glued to the top surface of the protrusions (rough surface) and the surface of the nonwoven fabric base fabric. They were joined and integrated into a water-permeable sheet.

When each of the permeable sheets obtained in Example 19 and Example 2 above was attached to the inner surface of a concrete form and concrete was poured under the same conditions, clean water was slowly drained downward and the concrete was converted to 1. When the mold was later removed, the mold was removed completely smoothly, and although solidified slag adhered to the surface, it was easily removed by washing with water.

Furthermore, there was no problem in attaching the nonwoven fabric to the formwork, and of course the surface of the concrete was smooth and dense, and its strength fully met the expected values.

Moreover, in the case where the synthetic resin plates obtained in Example 11 and Example 2 are bonded together, water absorption and water flow is carried out for a longer period of time, and the overall amount of water absorption and water is larger, compared to one in which the resin plates are not bonded. It was confirmed that the water absorption and drainage action was performed extremely smoothly.

(Effects of the Invention) As described above, the present invention provides a synthetic resin plate having small irregularities on the back layer of a nonwoven fabric base material consisting of three layers: a smooth surface layer, an intermediate layer, and a back layer having a base fabric. The smooth surface layer prevents the inflow of cement particles and moderately suppresses the water and air that floats up due to the breathing phenomenon at a moderate speed and slowly flows into the middle layer. At the same time, it is filtered by the intermediate layer, and even if some cement particles are mixed in, it is captured and slowly drained to the outside along with air as clear water, which improves the concrete surface due to the high water absorption rate. Not only does it prevent embrittlement and maintain the required strength on the concrete surface, but it also brings a smooth surface into contact with the concrete surface, improving the smoothness and density of the concrete surface and giving it a good external finish. have an effect.

In addition, since the above-mentioned smooth surface layer is in contact with the concrete surface, it is completely easy to release from the mold, and even if the slag attached to the surface dries, it is easily removed by washing with water, and it can withstand multiple uses, making it economical. As it thickens, the base fabric and fiber layer are integrated, so there is no need to worry about peeling between the eyebrows when the mold is removed. be.

Furthermore, in the water-permeable sheet of the present invention, the non-woven fabric backing layer and the synthetic resin plate are integrally joined as described above, so water that has passed through the non-woven fabric base material passes through the gap between the non-woven fabric sheet and the bottom of the recess of the synthetic resin plate. Therefore, even if it is pressed against the formwork side by concrete pressure after repeated use several times, it will not affect the joint surface of the formwork, and the former nonwoven fabric base material and formwork will be drained continuously. It can withstand repeated use several times without the risk of reducing drainage efficiency due to tight contact between the inner surfaces, and allows for downward drainage through the intermediate layer and downward drainage through the formwork joint surface over a long period of time. This has the effect of making it possible to continue draining and achieving extremely good concrete placement.

In addition, because of the above configuration, since the synthetic resin plate with small irregularities is bonded to the formwork, the adhesive application surface and the drainage gap surface are completely separated, so it is difficult to bond to the formwork. Although there are various methods, the simplest adhesive (with release paper) is available and is effective in simplifying the construction work.

[Brief explanation of drawings]

Fig. 1 is a partial cross-sectional view showing an example of a composite water-permeable sheet according to the present invention in a state of use, Fig. 2 (a) is a cross-sectional view showing an example of a synthetic resin plate, and ([+]) A plan view of the same resin board, Figures 3 ((), (D), and (c) are partial plan views showing each synthetic resin board of other shapes, respectively, and Figure 4 shows the flow of water and water in the water-permeable sheet. It is an explanatory sectional view for explaining. (1)...Fiber layer, (2)...Base fabric, (3)...Resin board, (4)...Surface layer, (5)...Middle Layer, (C)... Concrete, (P)... Formwork. Figure 1 (A) Figure (A) (B)

Claims (1)

[Claims] 1. A fibrous layer made of synthetic fibers and a synthetic fiber base fabric are integrated by needle punching, and the surface of the fibrous layer is heat treated to smooth it, and a surface layer is provided with ventilation and water permeable pores. , an intermediate layer having a cushioning function in the thickness direction, and a backing layer having a base fabric with good water permeability, which has air permeability and water permeable voids communicating with the above-mentioned air permeable and water permeable pores in the subsequent fiber layer, and a back layer having a base fabric with good water permeability. The base material is a non-woven fabric consisting of a structure,
A composite water-permeable sheet characterized in that a synthetic resin plate having a large number of small irregularities forming continuous passage gaps is integrally joined with the back layer of the synthetic resin plate with the top surface of the convex portions as the joint surface.