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JP-7856352-B1 - Concrete formwork panels

JP7856352B1JP 7856352 B1JP7856352 B1JP 7856352B1JP-7856352-B1

Abstract

[Problem] To provide a concrete formwork panel that can firmly hold nails without improving the flatness of the surface of hardened concrete and without worsening the efficiency of the work when removing the concrete formwork panel. [Solution] The concrete formwork panel 1 is a concrete formwork panel used for the weir plate 3 of the concrete formwork 2, and includes a pair of skin layers made of thermoplastic resin, a pair of intermediate layers laminated on each of the pair of skin layers and made of thermoplastic resin with a void ratio higher than that of the skin layers, and a core layer laminated between the pair of intermediate layers and made of thermoplastic resin with a void ratio lower than that of the intermediate layers. [Selection Diagram] Figure 1

Inventors

  • 南谷 英臣

Assignees

  • キョーセー株式会社

Dates

Publication Date
20260511
Application Date
20251030

Claims (3)

  1. A concrete formwork panel used as a dam board for concrete formwork, A pair of skin layers made of thermoplastic resin, A pair of intermediate layers are laminated on each of the aforementioned pair of skin layers, are made of thermoplastic resin, and have a porosity higher than that of the skin layers, A concrete formwork panel characterized by comprising a core layer laminated between the pair of intermediate layers, made of a thermoplastic resin, and having a porosity lower than that of the intermediate layers.
  2. The aforementioned skin layer has a porosity of 0.6 to 8%. The porosity of the pair of intermediate layers is 30 to 60%. The porosity of the core layer is 4 to 32%. The concrete formwork panel according to claim 1, characterized in that the difference between the void ratio of the pair of intermediate layers and the void ratio of the core layer is set to 20% or more.
  3. The concrete formwork panel according to claim 1, characterized in that the concrete formwork panel is made of the same thermoplastic resin.

Description

This invention relates to a resin concrete formwork panel that can be used as a formwork board for concrete pouring. Conventional concrete formwork panels are described, for example, in Patent Document 1. Patent Document 1 describes a concrete formwork panel produced by melt-kneading a polypropylene resin, biomass filler, and inorganic filler to obtain a resin composition adjusted so that the melt tension at 190°C is 10 mN to 100 mN and the melt flow rate (MFR) measured under conditions of 190°C and a load of 10 kg is 2 to 15. A foaming agent is added to 100 parts by weight of this resin composition, and then extruded and foam-molded pellets. Japanese Patent Publication No. 2024-176599 This is an enlarged cross-sectional view of a portion of a concrete formwork panel of one embodiment of the present invention.This is a perspective view showing an example of concrete formwork 2.This is a cross-sectional view of a portion of the concrete formwork 2.This is a schematic cross-sectional view showing the configuration of the five-layer concrete formwork panels 1a to 1c of Embodiment 1 of the present invention.This is a schematic cross-sectional view showing the configuration of the three-layer concrete formwork panels 20a to 20c of Comparative Example 1.This is a schematic cross-sectional view showing the configuration of the single-layer concrete formwork panels 30a to 20c of Comparative Example 2.The figures show the results of the nail head immersion test. (a) shows the state in which nails have been driven into concrete formwork panel 1a using a nail gun. (b) shows the state in which nails have been driven into concrete formwork panel 20a using a nail gun. (c) shows the state in which nails have been driven into concrete formwork panel 30a using a nail gun. Figure 1 is an enlarged cross-sectional view of a portion of a concrete formwork panel 1 according to one embodiment of the present invention. In Figure 1, voids are indicated by the black areas. The concrete formwork panel 1 of this embodiment includes a pair of skin layers A and E made of thermoplastic resin with a porosity of 0.6 to 8%, a pair of intermediate layers B and D laminated on each of the skin layers A and E and made of thermoplastic resin with a porosity of 30 to 60%, and a core layer C laminated between the pair of intermediate layers B and D and made of thermoplastic resin with a porosity of 4 to 32%. Here, the difference between the porosity of the pair of intermediate layers B and D and the porosity of the core layer C is set to 20% or more. For the sake of convenience in the following explanation, one of the pair of skin layers A and E mentioned above may be referred to as the first skin layer A, the other as the second skin layer E, one of the pair of intermediate layers B and D may be referred to as the first intermediate layer B, and the other as the second intermediate layer E. For example, the thickness T1 of the first skin layer A is 0.4 to 0.5 mm, the thickness T2 of the first intermediate layer B is 4.6 to 5.6 mm, the thickness T3 of the core layer C is 0.1 mm, the thickness T4 of the second intermediate layer D is 5.1 to 6.4 mm, and the thickness T5 of the first skin layer E is 0.3 to 0.6 mm. In this embodiment, the thermoplastic resin constituting the pair of skin layers A and E, the pair of intermediate layers B and D, and the core layer C is an acrylonitrile-butadiene-styrene copolymer synthetic resin (abbreviated as ABS resin). However, it is not limited to this, and for example, polypropylene resin, polyethylene resin, polystyrene resin, etc. may also be used. For reference, the porosities of the pair of skin layers A and E, the pair of intermediate layers B and D, and the core layer C are as follows: The porosity of the first skin layer A is 4.84%, the porosity of the first intermediate layer B is 14.89%, the porosity of the core layer C is 3.28%, the porosity of the second intermediate layer D is 18.18%, and the porosity of the second skin layer E is 2.47%. The surface hardness of skin layers A and E is selected to be 25 to 35, preferably 30, on the Rockwell hardness scale. <Method for measuring void ratio> The aforementioned method for measuring porosity will be explained using the example of measuring the porosity of intermediate layer B. First, using a contour machine, cuts are made from each end of the concrete formwork panel in the width direction perpendicular to the longitudinal direction, up to partway through the intermediate layer B. Next, the concrete formwork panel is gripped so that a crack surface is formed between the cuts (stress is concentrated), and a bending moment is applied in the direction that brings each end in the width direction closer together to cause it to break. The cross-section of intermediate layer B, excluding the portion cut with a contour machine, was imaged using a KEYENCE Corporation microscope (product name "VHX-8000") with a magnification set to 150x to 200x. To correct for focus mi