JP2002129506A - Method for finishing exposed-aggregate permeable concrete by washing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple construction method for exposed-aggregate permeable concrete by washing, which is finished excellently. SOLUTION: In a method for finishing exposed-aggregate permeable concrete in which the surface of placed permeable concrete is covered with a sheet impregnated with a retarder aqueous solution, permeable concrete is cured and uncured mortar section on a surface layer is washed away, the sheet is composed of a woven fabric of a nonwoven fabric, the retarder aqueous solution contains a water retentive substance and has viscosity having 1-50 mPa.S at 25 deg.C, the quantity of the retarder aqueous solution impregnated to the sheet is 150-600 g/m2, the surface of permeable concrete is covered with the sheet impregnated with the aqueous solution, and the sheet is covered with a water impermeable film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a concrete setting / hardening retarder (hereinafter referred to as a retarder in the present invention) among permeable concrete finishing methods such as permeable concrete pavement.
The present invention relates to a method for finishing permeable concrete washed out by using slag.

[0002]

2. Description of the Related Art Permeable concrete in which aggregates having a relatively uniform particle size are connected with a small amount of cement or mortar or other binders has a high water permeability. It is expected to contribute not only to the prevention of puddles and slips on roads in rainy weather, but also to the prevention of high temperature in the summer and the prevention of groundwater reduction in cities, because it leads quickly to the ground and drainage facilities.

[0003] The surface of a concrete structure, including permeable concrete, is generally gray and inferior in aesthetics. Therefore, in a construction emphasizing landscape, a part of the aggregate composed of natural stone or the like in the surface layer is exposed, and the beautiful natural stone is exposed. Aggregate exposed finish is used to decorate the surface. In the case of ordinary dense concrete, such a concrete aggregate finish finish is to spray a retarder on the poured concrete to delay the setting of the surface layer, and after the inside hardens to a certain strength, the surface It can be easily performed by a washing method in which the uncured mortar is washed out to expose the aggregate.However, in the case of permeable concrete, it is extremely difficult to form the aggregate exposed layer on the surface without dropping the aggregate. Have difficulty. In other words, when an aqueous solution of a retarder is sprayed to wash out the cement paste and mortar on the surface to expose the aggregate, the retarder wraps around the back surface of the aggregate and easily causes the aggregate to fall off. In addition, due to the water permeability, there is a problem that the retarder aqueous solution flows into the inside, delays the hardening of the cement inside, and significantly reduces the bonding force between the aggregates.

[0004] As a method currently used for the exposed finish of aggregates of permeable concrete, after the permeable concrete solidifies and reaches a required bonding strength between the aggregates, iron particles and sand particles are removed under high pressure. There are a shot blasting method in which a binder such as cement and mortar attached to the periphery of the aggregate on the surface is removed by spraying, and a water jet method in which the binder is removed by spraying ultra-high pressure water. (Sato Road Co., Ltd .: General catalog of permeable concrete pavement).
Further, a method has been proposed in which a viscous mixture of a retarder and a thickener is added to uncured permeable concrete, and after the inside is cured, the uncured binder in the surface layer is washed away (Japanese Patent Application Laid-Open No. HEI 9-208572). No. 9-286015). Further, the present inventors adhere a deformable sheet according to the unevenness of the surface of the permeable concrete on the cast permeable concrete,
A method of washing out the surface layer by impregnating the sheet with a retarder was proposed (described in Japanese Patent Application No. 11-213609).

[0005]

The above conventional method has the following problems that require improvement.

That is, the shot blasting method and the water jet method require large and expensive equipment, and are suitable for large-scale pavement work, but cannot be easily carried out by anyone. Furthermore, the shot blast method has a problem of damaging the surface of the aggregate because hard particles are sprayed at high speed on the surface of the permeable concrete, and the water jet method has a problem in that ultra-high pressure water is sprayed on the surface of the permeable concrete. There was a problem with the finish such as not only the mortar and mortar but also some of the aggregates fell off. In addition, the method of spraying the thickened retarder is that if the viscosity of the aqueous solution of the retarder is low, the retarder permeates more than necessary through the continuous voids of the water-permeable concrete, and excessive washing is exposed. There is a possibility that the holding power of the aggregate may be significantly weakened. Conversely, if the viscosity of the aqueous retarder solution is too high, there is a problem that spraying becomes difficult. In the method described in Japanese Patent Application No. 11-213609, good results can be obtained when the conditions are set optimally, but the optimal conditions are not clarified.

As described above, the exposed finish of the permeable concrete aggregate suitable for the landscape incorporates many unsolved technical problems, is easy to construct, can be carried out in any place, and has a good finish. The development of new construction methods is awaited.

[0008]

Means for Solving the Problems In order to achieve the above-mentioned object of the present invention, the present invention is configured as described in the claims.

In other words, the surface of the cast permeable concrete is covered with a sheet impregnated with an aqueous retarder solution, the permeable concrete is cured, and the uncured mortar of the surface layer is washed away. The sheet is made of a woven or non-woven fabric, the aqueous retarder solution contains a water retention material, and at 25 ° C,
A viscosity of 50 mPa · s, the impregnating amount of the aqueous retarder solution into the sheet is 150 to 600 g / m ² , and the surface of the permeable concrete is coated with the sheet impregnated with the aqueous retarder solution. And coating the sheet with a water-impermeable film.

Further, in the above-mentioned method of finishing the washed-out permeable concrete, the viscosity of the aqueous retarder solution at 25 ° C. is 1.5 to 15 mPa · s, and the impregnating amount of the aqueous retardant solution into the sheet is 200 to 400 g / g. and m ^2.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS When concrete is cast, it is found that breathing water appears on the surface when the concrete is cast. No water is lost. In contrast, permeable concrete is cast with a composition with extremely low moisture, and in order to express water permeability, there are many continuous voids, and therefore, cast under climatic conditions of extremely low temperature and high humidity. Unless otherwise, the water in the surface layer is lost in a very short time after the casting. Therefore, in the case of ordinary concrete, not only a liquid retarder but also a method of coating the surface with a dry retarder impregnated with the retarder can sufficiently delay the setting of the concrete and wash it out. However, in the case of permeable concrete, since the water content is small and the surface is dried quickly, the effect of the retarder cannot be exhibited unless measures are taken to prevent the evaporation of water.

[0012] As in the method of finishing washed-out permeable concrete according to claim 1 or 2, a water-retaining substance is contained in the aqueous retarder solution, and the aqueous solution of the retarder is necessary and sufficient for a sheet made of woven or non-woven fabric. When applied to the permeable concrete surface after being impregnated in an appropriate amount, the permeable concrete surface can be brought into contact with the retarder in a state where sufficient moisture is present. Furthermore, after coating the sheet impregnated with the aqueous retarder solution, immediately by coating a film that does not transmit water at all, evaporation of water is prevented,
The effect of the retarder lasts over a necessary and sufficient time range.

[0013] As described above, since the water-permeable concrete has continuous voids formed therein, if the amount of the aqueous solution of the retarder impregnated in the sheet is excessive, the aqueous solution of the retardant that cannot be held by the sheet can be used. However, the water penetrates into the permeable concrete and causes poor curing, and sometimes the strength is impaired to the extent that the concrete collapses. Therefore, the amount of impregnation of the sheet with the aqueous retarder solution must be within the range that the sheet can hold. The holding amount of the retarder aqueous solution in the sheet depends on the viscosity of the retarder aqueous solution, and the higher the viscosity, the larger the holding amount. On the other hand, if the viscosity is too high, it becomes difficult to impregnate the sheet with the aqueous retarder solution, which significantly impairs the workability. Therefore, there is a proper viscosity.

According to an experiment, it was found that the retention of the retarder aqueous solution in the sheet was improved only by adding a slight amount of a thickener to the aqueous retarder solution and making the viscosity at 25 ° C. 1 mPa · s. (Reference: The viscosity at 25 ° C. and 0.1 MPa of water is 0.89 mPa · s). When the viscosity of the retarder aqueous solution is further increased, the retention of the retarder aqueous solution of the sheet is dramatically improved. However, when the viscosity exceeds 50 mPa · s, the workability is remarkably reduced and the sheet becomes impractical. The impregnation amount of the aqueous solution far exceeds the required amount, and the material is wasted. Therefore, the appropriate viscosity of the aqueous retarder solution is 1 to 50 mPa · s at 25 ° C. The more preferable viscosity range of the aqueous solution of the retarder for impregnating the sheet with a sufficient amount to exert the retarding effect with good workability was 1.5 to 15 mPa · s at 25 ° C.

The amount of the aqueous retarder solution impregnated in the sheet is extremely important for exhibiting the effect of the retarder.
If the amount is too small, the amount of the retardant that permeates the surface layer of the permeable concrete with which the sheet is in contact is insufficient, and the washing is incomplete. On the other hand, if the amount is too large, the excess aqueous solution of the retarder penetrates into the permeable concrete and lowers the strength of the concrete. In order to sufficiently exert the effect of the retarder, the impregnation amount of the aqueous retarder solution into the sheet must be 150 g / m ² or more. Preferably, 200 g / m ² or more is safe. On the other hand, if it exceeds 600 g / m ² , there is a possibility that the aqueous retarder solution permeates into the permeable concrete. It is also important to prevent useless consumption of the retarder, and preferably 400 g / m ² or less.

The above-mentioned retarders affect the hydration reaction of cement and delay the setting and hardening time of mortar and concrete, and are of organic type and inorganic type. Currently, commercially available and widely used organic compounds include lignin sulfonates, gluconates, oxycarboxylates, and polyol polymer complexes, and inorganic compounds include silicofluorides and phosphates. There is. In the present invention, any of these can be appropriately selected and used, and there is no particular limitation on the type, but it is not preferable that a large amount of colloidal substance is added in advance.

In order to maintain the viscosity of the aqueous retarder solution, various commercially available thickeners can be used. For example, natural products include modified cellulose derivatives, polysaccharides and the like, and synthetic materials include acrylate resins and the like. An optimal thickener may be selected in consideration of compatibility with a retarder and the like.

As described above, it is extremely important to include a water retention material in the aqueous retarder solution. As the water retention material, for example, glycol polymers and oligomers are excellent. Further, the above-mentioned thickener also has water retention. Many of the above-mentioned retarders have a skeleton structure such as polysaccharides, polyols, and oxycarboxylic acids, and these also maintain water retention.

The sheet for impregnating the aqueous retarder solution has both the holding property and the permeability of the aqueous retarder solution, and a woven or nonwoven fabric is suitable. The material may be made of natural fibers such as cotton, or may be made of synthetic fibers such as polyester. The thickness of the woven or non-woven fabric, the thickness of the fibers, the degree of clogging of the eyes, etc., affect the retention of the retarder aqueous solution, but those suitable for the present invention include a woven fabric having a basis weight of 80 to 150 g / m about ^2, in the non-woven fabric, 50 to 80 g / ^{m 2}
It is about. In order for the aqueous retarder solution to easily and uniformly permeate into the sheet for impregnating the aqueous retarder solution, and to be retained in the sheet, it is desirable that the sheet is hydrophilic. When the sheet for impregnating the aqueous retarder solution is made of a hydrophobic material, measures such as preliminarily subjecting the sheet to hydrophilic treatment with a surfactant solution or the like or using a retarder aqueous solution to which a surfactant is added are taken. It is desirable to take.

When the surface of the permeable concrete is washed out, a sheet impregnated with the aqueous retarder solution is coated with a water-impermeable film, and during curing of the permeable concrete, drying of the sheet and the concrete surface layer occurs. It is necessary to avoid it. If this is not performed, the effect of the retarder will not be sufficiently exhibited, and washing out may be insufficient. As the water impermeable film, a commercially available polymer film can be used.

By using a sheet impregnated with an appropriately adjusted retarder aqueous solution as in the present invention, the permeable concrete can be easily washed out at any cost at low cost. At this time, since the excess retarder aqueous solution does not permeate into the inside through the continuous voids of the permeable concrete, it does not hinder the hardening of the binder of the concrete, and also reduces the permeability of the permeable concrete. Since there is no such thing, it is possible to finish extremely high-performance washable permeable concrete. Also,
By using a sheet impregnated with the aqueous solution of the retarder,
Most of the extra retarder or coloring material added to the retarder remains on the sheet and is removed, and most of the binder coated on the upper surface of the aggregate to be washed adheres to the sheet. Removed. Therefore, the amount of waste discharged together with the washing water is significantly reduced, and the load of wastewater treatment accompanying the washing step can be reduced.

In the present method using a sheet impregnated with an aqueous retarder solution, it is necessary that the sheet and the surface of the permeable concrete adhere to each other. When the sheet impregnated with the aqueous retarder solution is easily stretched by being wetted with the aqueous retarder solution, the sheet is merely placed on the permeable concrete, and both are adhered to the required degree, but generally a soft roller is used. By performing such operations, the adhesion becomes more complete.

The permeable concrete to which the present invention is applied is obtained by covering an aggregate having a limited particle size with a cement mixture and using the aggregate as a binder to bond the aggregates together. Is about 5 to 30%, and the voids are continuous and have a structure that allows water to permeate. A great deal of knowledge has been obtained so far on the composition and construction method of permeable concrete, and permeable concrete can be constructed with reference to them.

In order for the water-permeable concrete to exhibit the water-permeation function, continuous voids must be formed therein as described above. Permeability is lost if a continuous void inside is cut off somewhere. As a method of finishing the surface of permeable concrete, a decorative finish in which decorative natural stones are arranged on the surface of the permeable concrete that has been cast can be considered. A large amount of binder is required, which results in the formation of a continuous dense layer on the surface and impairs water permeability. Therefore, as a surface decorative finish of the permeable concrete, a method of casting the permeable concrete and then removing a part of the binder around the aggregate on the surface to expose the aggregate is suitable. In order to finish the exposed surface of the aggregate beautifully by this method, a washing-out method using a retarder is optimal.

What is important in the method of washing out permeable concrete using a retarder is that the retarder acts effectively on the binder in the portion of the cast permeable concrete where the aggregate is to be exposed. That is. Since permeable concrete has a structure in which aggregates are bonded to each other with a very small amount of binder, the surface thereof is not flat, and irregularities created by the aggregate covered by a small amount of the binder appear as they are. The retarder has to be applied only to the required upper part of this protruding aggregate. In addition, since this part remarkably dries rapidly, it is important to use a retarder while suppressing the drying. In addition, since permeable concrete has voids continuously from the surface, if the application is incorrect, the retarder will flow into the interior through the continuous voids and hinder the internal setting and hardening, so the retarder Must be prevented from flowing into the interior. The use of the sheet impregnated with the aqueous retarder solution according to the present invention can easily satisfy the above requirements. That is, the sheet impregnated with the aqueous retarder solution has a property of retaining the aqueous solution of retarder and a property of allowing the retained aqueous solution of retarder to seep out to the surface of the permeable concrete in an appropriate amount, and is mechanically flexible and weak. It is easily deformed by force and adheres sufficiently to the aggregate upper surface of the permeable concrete surface as necessary to allow the retarder to penetrate into the binder.

In order to expose the aggregate on the surface of the permeable concrete, water may be sprayed on the surface of the permeable concrete to wash out the unhardened cement paste and mortar together with the retarder.

[0027]

[Example 1] Commercially available carboxymethylcellulose was added to an aqueous solution containing 5% of an oxycarboxylic acid-based retarder (PARIC T manufactured by FPC) and 0.1% of a nonionic surfactant. A retardant aqueous solution having a different viscosity is prepared by appropriately adding the aqueous solution, and the resultant is immersed in a polyester nonwoven fabric having a basis weight of 60 g / m ² (Unicell Rampass manufactured by Unicell Corp.), drained for a predetermined time, and the impregnation amount of the aqueous retardant solution is determined. Was.

On the other hand, 100 parts by weight of ordinary Portland cement, 50 parts by weight of river sand having a particle size of 1 mm or less, and a particle size of 7 to 12 mm
A mixture of 550 parts by weight of natural stone, 0.4 parts by weight of a melamine-based water reducing agent, 10 parts by weight of a 30% SBR emulsion, and 24 parts by weight of water was kneaded well with a mixer. The kneaded mixture was poured into a mold having a thickness of 50 mm, and was firmly adhered to produce a permeable concrete test piece. A sheet made of a nonwoven fabric impregnated with the above aqueous retarder solution was placed on the surface, and was brought into close contact with a rubber roller. Next, the sheet was covered with a vinyl sheet and cured at room temperature (about 25 ° C.) for 20 hours. After curing, remove the vinyl sheet and the sheet made of non-woven fabric impregnated with the retarder aqueous solution,
Water was sprayed to check whether washing was possible. The results are shown in Table 1. The results in the table are obtained by using a sheet made of a polyester nonwoven fabric having a basis weight of 60 g / m ² and draining the water for the time shown in the table. If these conditions are different, a sheet made of a woven fabric or a nonwoven fabric of an aqueous retarder solution is used. Impregnation amounts are different.

[0029]

[Table 1] [Example 2] Oxycarboxylic acid-based retarder (FPP
Includes 5% of PALIC T manufactured by K Corporation, 0.4% of water-soluble cellulose ether (hi-metroze manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.1% of nonionic surfactant. A polyester nonwoven fabric having a basis weight of 60 g / m ² (Unicell Rampass manufactured by Unicell Corp.) is immersed in an aqueous solution of an agent, and then placed on a wire mesh to remove excess liquid, and the nonwoven fabric impregnated with an aqueous solution of a retarder of 480 g / m ^2. Was produced.

On the other hand, 100 parts by weight of ordinary Portland cement, 50 parts by weight of river sand having a particle size of 1 mm or less, and a particle size of 7 to 12 mm
A mixture of 550 parts by weight of natural stone, 0.4 parts by weight of a melamine-based water reducing agent, 10 parts by weight of a 30% SBR emulsion, and 24 parts by weight of water was kneaded well with a mixer. The kneaded mixture was poured into a mold having a thickness of 50 mm, and was firmly adhered to obtain a permeable concrete. The sheet made of nonwoven fabric impregnated with the aqueous retarder solution was coated on the permeable concrete, and brought into close contact with a rubber roller. Next, the sheet was covered with a vinyl sheet and cured at room temperature (about 25 ° C.) for 20 hours. After the curing, the vinyl sheet and the sheet made of the nonwoven fabric were removed, and water was sprayed to wash off the uncured binder in the surface layer, thereby exposing the aggregate made of natural stone. Thereby, the upper part of the aggregate of the surface layer is almost 1/3 to 1
/ 2 The exposed permeable concrete was obtained. There was no clogging of the voids inside the permeable concrete due to the washed away binder, and the permeability was 4.1 × 10 ⁻¹ cm / s. It was unchanged at 2 × 10 ⁻¹ cm / s. [Example 3] Oxycarboxylic acid-based retarder (FPP
A viscosity of 3.9 mPa · s at 25 ° C. containing 5% of PALICK T manufactured by K Corporation, 0.2% of water-soluble cellulose ether (hi-metroze manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.1% of a nonionic surfactant. of the retarder aqueous solution to basis weight was immersed a commercially available cotton fabric 110g / m ^2, cut the excess liquid and placed on a wire mesh, a sheet made of a woven fabric which has a delay aqueous solution 320 g / m ² impregnated Produced.

Using a sheet made of a woven fabric impregnated with the above-mentioned retarder, washing was performed in the same manner as in Example 2 to produce a permeable concrete. Also in this example, a washed out permeable concrete in which the upper part of the aggregate of the surface layer was exposed to about 1/3 to 1/2 was obtained. There was no clogging of the voids inside the permeable concrete due to the washed away binder, and the permeable coefficient was 4.0 × 10 ⁻¹ cm / s.

[0032]

As described above, according to the present invention, the surface of the poured permeable concrete is covered with the sheet impregnated with the aqueous retarder solution, the permeable concrete is cured, and the uncured mortar of the surface layer is washed away. In the method of finishing washed-out permeable concrete, the sheet is made of a woven or non-woven fabric, the aqueous retarder solution contains a water-retaining material, and the viscosity of the aqueous retarder solution at 25 ° C is 1 to 5
0 mPa · s, the impregnating amount of the aqueous retarder solution into the sheet is 150 to 600 g / m ² , and the surface of the permeable concrete is coated with the sheet impregnated with the aqueous retarder solution, In order to cover the water-impermeable film, it is possible for the permeable concrete surface to come into contact with the retarder in a state where sufficient moisture is present. In addition, evaporation of water is prevented, and the effect of the retarder is maintained over a necessary and sufficient time range. Further, the sheet is excellent in holding the retarder aqueous solution, and the sheet can be impregnated with the retarder aqueous solution with good workability. In addition, the surface of the permeable concrete can be sufficiently washed out without the excess retarder aqueous solution penetrating into the permeable concrete and reducing the strength of the concrete.

Further, according to the present invention, the amount of a binder or a retarder such as cement discharged into the washing water at the time of washing can be significantly reduced, and the load of wastewater treatment accompanying the washing can be reduced.

Further, in the above-mentioned method for finishing washed-out permeable concrete, the viscosity of the aqueous retarder solution at 25 ° C. is 1.5 to 15 mPa · s, and the impregnated amount of the aqueous retardant solution into a sheet is 200 to 400 g / g. because m ^2, and the sheet can be impregnated well workability retarders aqueous superior retarder solution retention, in the sheet. In addition, the surface of the permeable concrete can be sufficiently washed out without the excess retarder aqueous solution penetrating into the permeable concrete and reducing the strength of the concrete.

Claims (2)

[Claims] 1. A retarder water is applied to a surface of a permeable concrete poured in.
Cover the sheet impregnated with the solution,
Cure, wash off the uncured mortar of the surface layer, wash
In the method of finishing exposed permeable concrete,
Is made of woven or non-woven fabric, and the aqueous solution of retarder
Contains an aqueous substance and at 25 ° C. 1 to 50 mPa · s
Impregnating the sheet with the aqueous retarder solution
150-600g / m ²And the permeable condenser
Cleat surface impregnated with retarder aqueous solution
After coating, a water-impermeable film is coated on the sheet.
Washable permeable concrete finish characterized by
Construction method. 2. The retarder aqueous solution has a viscosity at 25 ° C. of 1.5 to 15 mPa · s, and the impregnating amount of the retarder aqueous solution in the sheet is 200 to 400 g / m ^2. The method for finishing washed-out permeable concrete according to claim 1.