JP5010519B2 - Manufacturing method of precast concrete products with improved roughness coefficient - Google Patents

Description

  The present invention relates to a method for producing a precast concrete product, particularly a product having an improved roughness coefficient of the inner surface of a precast concrete culvert.

  Conventionally, a resin sheet is often coated on the inner surface of a waterway member such as a box culvert or an arch culvert for the purpose of waterproofing, improving the roughness coefficient, and improving the durability.

  In order to implement these methods, there is a standard of the Japan Sewerage Association, and many ideas have been proposed and implemented.

  The present invention proposes a new method conforming to the standard.

  The roughness coefficient of the concrete surface is generally said to be 0.013. Since the roughness coefficient of 0.013 is used for the calculation of the empty section of the precast concrete underdrain determined from the planned flow rate, the inner surface is made of a resin material (generally rough surface). The cross section needs to be larger than when coated with a degree coefficient of 0.010).

  When the cross section becomes large, it is necessary to increase the thickness of the member, and as the product weight increases, the transportation cost increases and the construction crane capacity also increases, so the construction cost increases.

  When used in corrosive environments such as sewer pipes and merging pipes, corrosion of concrete becomes a problem, so it is necessary to take anticorrosion measures such as increasing the cover of the reinforcing bars and providing a wear allowance to increase durability. . This increases the thickness of the member, which increases the construction cost.

  Therefore, for example, as shown in Patent Document 1, a concrete surface is coated with a resin material or the like to reduce the roughness coefficient and improve the durability. However, it is applied to the manufactured product or installed at the construction site. It takes time and effort to cover the product, and because the lining plate made of thermoplastic resin is fixed to the inner surface of the water channel by anchor projection and concrete filling, etc., the air cross section in the water channel becomes narrower and the flow rate of the water channel decreases. There is a problem.

  On the other hand, an outer waterproof pre-sheet has been developed for a waterproof layer on a concrete surface (see, for example, Patent Document 2). This outer waterproof pre-sheet has a surface coating with fine hooks of inorganic particles that react with the hydroxide from the hydration reaction of concrete or mortar to form a hydrated product on the surface in contact with the concrete, It creates permanent adhesion with concrete.

  This outer waterproof pre-sheet is used for outer waterproofing of horizontal slab concrete, vertical walls, and the like, and is also used for a prior construction method that is applied before the concrete is placed. Therefore, in the prior art, an outer waterproof pre-sheet is attached to an external formwork of in-situ concrete, and the concrete is cast to form a waterproof layer on the outer surface of the concrete. At the time of production of the precast concrete product, the outer waterproof pre-sheet was not directly attached to the surface of the precast concrete product.

  Conventional waterproofing of precast concrete products involves applying or sticking a waterproof material to the concrete surface before delivery on site, but it takes time and effort to apply and paste. Alternatively, after the precast concrete product is installed at the construction site, a waterproof material is applied or pasted on the concrete surface, but it takes time to apply and paste.

  In order to eliminate such labor, when using the above waterproofing pre-sheet for waterproofing precast concrete products and attaching the waterproof sheet to the inner surface of the precast concrete underdrain, the inside of the steel mold for concrete placement In order to fix the sheet-like material to the mold surface, it is necessary to process the joint portion on the inner surface of the mold frame, and it is difficult to easily and reliably fix the sheet-like material to the inner surface of the mold frame.

JP 2007-154451 A JP-T-2004-513801

  The object of the present invention is to simplify the process of covering and integrating the sheet on the precast concrete product, reduce the roughness coefficient of the precast concrete product, improve the durability of the precast concrete product such as chemical resistance and wear resistance, The purpose is to simplify the work of fixing the sheet to the formwork surface.

  In this invention, an improved sheet is arranged on the inner mold surface, a belt-like support plate having magnets arranged at a required interval is placed along the improved sheet, and the improved sheet is temporarily fixed, and between the inner mold frame and the outer mold frame. Roughness coefficient is characterized in that concrete is placed in, the magnet and the belt-like support plate are pulled out while the concrete is not hardened, the improved sheet is left on the inner surface of the concrete, and the inner and outer molds are demolded. This is a method for producing an improved precast concrete product (claim 1). An improved sheet is integrally attached to the concrete inner surface of the precast concrete product during the manufacture of the precast concrete product such as the culvert and the open channel forming the water channel.

  It is preferable to arrange a fluororesin sheet between the improved sheet and the belt-like support plate (claim 2). Since the belt-like support slides on the surface of the fluororesin sheet, the belt-like support can be easily pulled out.

  The improved sheet has a waterproof layer that is in contact with water, a resin sheet, an adhesive layer that is in contact with concrete is made of an adhesive or elastomer, and has fine hooks that bind to the concrete. -It is preferable to use an improved sheet layer that can improve adhesion, improve durability (chemical resistance, wear resistance), and the like (Claim 3). Furthermore, the fine hook preferably uses inorganic particles that react with a hydroxide solution from the hydration reaction of concrete or mortar to produce a hydrated product.

  That is, it is preferable to use the outer waterproof pre-sheet disclosed in Patent Document 2 as the improved sheet of the present invention. Specifically, for example, the following materials can be used for each member.

(1) Resin sheet: flexible sheet such as polyethylene (high density polyethylene is preferred)

(2) Adhesive (preferably pressure-sensitive waterproof adhesive) or elastomer (rubber-like elastic body) ... rubber-modified bitumen or butyl rubber, polyisobutylene, acrylic, vinyl ether, styrene-isoprene-styrene, styrene-butadiene- Synthetic adhesive selected from the group consisting of styrene, styrene-ethylene-butylene-styrene, styrene-butadiene-styrene and ethylene-propylene-diene monomers

(3) Inorganic particles (including curing accelerators, strength accelerators, etc.)… (a) Aluminum oxide trihydrate; (b) Silica dioxide; (c) Fly ash; (d) Injection furnace slag (blast furnace slag), (e) silica fume; (f) alkali or alkaline earth metal nitrites, nitrates, halides, sulfates, hydroxides, carboxylates, silicates or aluminates Salt or mixtures thereof

  As a specific structure of the improved sheet layer of the present invention, as illustrated in FIG. 5, a resin sheet, an adhesive or elastomer layer provided on the concrete surface side, and embedded in the surface of this layer. There are a three-layer structure of inorganic particle layers, or a four-layer structure in which the surface of inorganic particles is coated with a water-soluble coating layer, as illustrated in FIG.

  (1) It is possible to simplify the work of covering and integrating the sheet on the inner surface of the precast concrete product.

  (2) The roughness coefficient of the inner surface of the precast concrete product can be reduced, and the cross section can be reduced.

  (3) The durability (chemical resistance, wear resistance, etc.) of the inner surface of precast concrete products can be improved.

  (4) The waterproofness of the precast concrete product can be secured.

  (5) The adhesion between the precast concrete product and the sheet can be improved.

  (6) Since the concrete surface is covered with a sheet and the evaporation of moisture in the concrete is suppressed during demolding after steam curing, drying shrinkage of the product can be prevented.

  (7) Since the improved sheet is temporarily fixed to the mold surface with a belt-like support plate with a magnet, the joining process can be omitted. The improved sheet can be easily fixed to the mold surface, and the belt-like support plate can be removed from the mold by pulling out the belt-like support plate while the concrete is uncured.

  (8) As a result, the overall construction cost of precast concrete products with excellent water channel performance can be reduced.

  As shown in FIG. 1, when manufacturing a precast concrete culvert, etc., the inner surface of the precast concrete culvert is made from a roughness coefficient improving sheet layer 1 having a waterproof layer A, an adhesion layer B, and a fine hook layer C in order from the inside. Cover.

  When covering, as shown in FIGS. 1 and 4, the surface of the waterproof layer A of the improved sheet layer 1 is attached to the surface of the inner mold 4, and the concrete 6 is placed between the outer mold 5 and the inner mold 4. By placing, the fine hook layer C on the surface of the adhesion layer B and the concrete are integrated, and the improved sheet layer 1 is integrally attached to the inner surface of a precast concrete undergrowth or the like. By attaching the improved sheet layer 1 to the surface of the inner mold 4, the covering work can be performed simultaneously with the concrete placing.

  When the improved sheet layer 1 is disposed on the surface of the inner mold 4, as shown in FIGS. 1 to 3, a belt-like support plate 3 (thickness) made of a steel plate or the like with magnets 2 (10 to 45 mm) arranged at required intervals. 1 to 2 mm, width 20 to 30 mm) along the improved sheet layer 1 stretched on the surface of the inner mold 4, and the improved sheet layer 1 is temporarily fixed to the surface of the inner mold 4 by the action of the magnet 2. .

  As shown in FIG. 4, the fluororesin sheet 7 is sandwiched between the improved sheet layer 1 and the belt-like support plate 3 so that the improved sheet layer 1 and the belt-like support plate 3 are not in direct contact with each other. preferable.

  Next, concrete 6 is placed between the inner mold 4 and the outer mold 5, and the strip-like support plate 3 with the magnet 2 is pulled out while the concrete 6 is uncured, and vibrations are applied to the concrete. Accustom. Due to the smooth surface of the fluororesin sheet 7, the belt-like support plate 3 can be easily pulled out. The fluororesin sheet 7 is also removed from the surface of the improved sheet layer 1.

  Next, the inner and outer molds 4 and 5 are removed.

  The improved sheet layer 1 uses an outer waterproof pre-sheet described in Patent Document 2. This outer waterproof pre-sheet is usually used as an underground waterproof material in an outer waterproof advance method. As shown in FIGS. 4, 5, and 6, this sheet has a multi-layer structure, has a thickness of 1.0 to 1.2 mm, and has a surface in contact with water, that is, a waterproof layer A such as high-density polyethylene. The resin sheet 11, the surface in contact with concrete, that is, the adhesive layer B is made of an adhesive or elastomer 12 such as acrylic, and the fine hook layer C on the surface of the adhesive layer B is made of inorganic particles 13 such as aluminum oxide trihydrate of 50 to 100 μm, for example. It consists of a fine hook designed and scientifically designed with a coating to produce permanent adhesion while non-anchor.

  In the embodiment of FIG. 5, a pressure-sensitive waterproof adhesive or elastomer 12 is provided on the surface of a resin sheet 11 such as high-density polyethylene, and the surface reacts with a hydroxide solution from the hydration reaction of concrete or mortar. Thus, a fine hook layer is provided by the inorganic particles 13 that produce a hydrated product.

  In the embodiment of FIG. 6, the coating layer 14 is provided on the layer of the inorganic particles 13. This coating layer 14 is in contact with a water-soluble material (eg ethylene vinyl acetate, polyvinyl alcohol), an alkali-soluble material (eg latex) or a hydraulic cementitious composition cast against the modified sheet layer 1. Consists of other materials through which particles can diffuse. Inorganic particles 14 can be attached to a layer of pressure sensitive waterproof adhesive or elastomer 12.

  If the sheet can be used as an inner surface covering material and the roughness coefficient (coefficient related to the flow rate due to the roughness of the water channel surface) can be improved, it is possible to reduce the internal cross section of the water channel member such as a box culvert. Further, when used in a corrosive environment, durability can be expected to be improved by the effect of a sheet layer having higher durability than concrete. From the above, a basic test and a manufacturing test were conducted in order to realize a product using the outer waterproof pre-seat. The roughness coefficient is 0.013 in the concrete channel, the roughness coefficient is 0.010 by the outer waterproof pre-seat, and the culvert section can be reduced by about 10%. For this reason, the effect of reducing the overall construction cost can be demonstrated with a larger cross section.

As shown in the figure, the present invention can be implemented on four sides like a box culvert, and can be implemented on three sides like a U-shaped groove, and an improved sheet is arranged only on the necessary side of a precast concrete product. can do.

It is a cross-sectional view of the manufacturing process of the precast concrete product of this invention. It is a front view of the sheet | seat used by this invention. It is a front view of a magnet. It is an expanded sectional view of the principal part. It is sectional drawing which shows an example of the pre-seat for external waterproofing utilized by this invention. It is sectional drawing which shows the other example of the outer waterproof pre-sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Roughness coefficient improvement sheet layer 2 ... Magnet 3 ... Support plate 4 ... Inner formwork 5 ... Outer formwork 6 ... Concrete 7 ... Fluorine resin sheet A ... Waterproof layer B ... Adhesion layer C ... Fine hook layer 11 ... Resin sheet 12 ... Adhesive or elastomer 13 ... Inorganic particles 14 ... Coating layer

Claims (4)

  Place the improved sheet on the inner mold surface, place a belt-like support plate with magnets at the required intervals along the improved sheet, temporarily fix the improved sheet, and place concrete between the inner mold frame and the outer mold frame Precast concrete with improved roughness coefficient, wherein the magnet and the belt-like support plate are pulled out while the concrete is uncured, and the inner and outer molds are removed while leaving the improved sheet on the inner surface of the concrete. The manufacturing method of the product.   An improved sheet is placed on the inner mold surface, a belt-like support plate with magnets arranged at required intervals is placed along the improved sheet, and the improved sheet is temporarily fixed, and a fluororesin sheet is inserted between the improved sheet and the belt-like support plate, Concrete is placed between the inner mold frame and the outer mold frame, the magnet, the belt-like support plate and the fluororesin sheet are pulled out while the concrete is not cured, and the modified sheet is left on the inner surface of the concrete, A method for producing a precast concrete product with improved roughness coefficient, characterized by demolding the formwork.   The improved sheet is an improved sheet layer in which the waterproof layer in contact with water is made of a resin sheet, the adhesive layer in contact with concrete is made of an adhesive or an elastomer, and has fine hooks bonded to the concrete. The manufacturing method of the precast concrete product which improved the roughness coefficient in any one of 2.   4. The method for producing a precast concrete product with improved roughness coefficient according to claim 3, wherein the fine hook is an inorganic particle that reacts with a hydroxide solution from a hydration reaction of concrete or mortar to form a hydrated product.

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