JP3245648B2 - Concrete formwork - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a formwork for construction (including a formwork for civil engineering work) used in concrete casting work and the like, particularly to a concrete formwork made of synthetic resin.

[0002]

2. Description of the Related Art Conventionally, as a form frame of this type, a hard and thick wood plywood or steel plate is used as a face plate, and flanges (including square members) and ribs (including square members) are formed from the periphery thereof. It is a standing structure.

[0003] Therefore, conventional molds generally have a considerably large weight and are not always easy to handle. In the case of wooden molds, the weight increases due to water absorption, and the surface warps due to repeated water absorption and drying. There was also a problem in durability. In addition, since the surface layer of the hardened concrete adheres to the steel plate or the wooden board, not only irregularities are generated on the concrete surface after removing the formwork, but also the concrete attached to the formwork surface must be removed before the next use. No.

[0004]

For this reason, some attempts have been made to extrude or draw an aluminum material into a "harmonic" cross section for the purpose of weight reduction. Extrusion or pulling out of irregularly shaped structural members is by no means easy, and daring to do so would lead to increased manufacturing costs. Further, aluminum has an affinity for concrete, like steel and wood, so that the problem that hardened concrete adheres to the surface of the aluminum formwork remains unsolved.

[0005] Accordingly, an object of the present invention is to provide not only excellent releasability from concrete but also excellent impact resistance and toughness at low temperatures, and therefore excellent durability, and easy molding by extrusion or injection. Flanges, ribs, etc., that is, portions defining the thickness of the formwork are integrally formed on the peripheral edge and / or the central portion of the face plate at a key point, and are particularly integral parts of a required or common dimension. SUMMARY OF THE INVENTION An object of the present invention is to provide a concrete form in the form of a unit frame having a size and to solve the conventional problems at once.

[0006]

The outline of the present invention which has achieved the above object will be described first with reference to the reference numerals in the drawings. A concrete form according to the present invention comprises a face plate (1) serving as a concrete casting surface, A shape integrally provided with formwork thickness defining portions (2), (2), (3), (3), ... which are provided continuously in a direction substantially perpendicular to the face plate (1). Molded into a synthetic resin composition, the synthetic resin composition is a thermoplastic resin and paraffin wax kneaded uniformly, this paraffin wax,
The average number of carbon atoms in one molecule is 20 to 35 and the average molecular weight is 3
It is a hydrocarbon mixture having a linear saturated hydrocarbon of 00 to 500 as a main component and a melting point in the range of 60 to 80 ° C, and contained in the synthetic resin composition in an amount of 1 to 10% by weight. It is characterized by the following.

As thermoplastic synthetic resins which can be easily extruded or injection-molded, suitable synthetic resins having excellent releasability and durability and excellent compatibility with paraffin wax, for example, polypropylene resin, What is necessary is just to select from a polyethylene resin, an acrylic resin, a polycarbonate resin, etc.

[0008] The paraffin wax and the thermoplastic resin may be kneaded in advance before molding. However, by adding both chips at a predetermined weight ratio to an extruder provided in a molding apparatus, the extruder is extruded. The kneading may be performed immediately before molding, that is, simultaneously with molding in the inside of the ruder. If the content of paraffin wax in the resin mixture is extremely less than about 1% by weight, the desired effect cannot be obtained. Conversely, if the content of paraffin wax is extremely greater than about 10% by weight, a molded article is obtained. The mechanical strength of the concrete barrel is significantly reduced, both of which are disadvantageous.

[0009] The part of the form thickness that is continuously provided on the face plate is 1
It may be a flange along the opposing side edges of the pair, or, in addition to the flange portion, an arbitrary shape and an arbitrary number of concave portions formed perpendicular to the face plate. In the former case, a complicated molding die is unnecessary, and by extrusion from a simple die, for example, it is molded as a long object such as 600 mm width or 900 mm width, and after extrusion, 900 mm length or 1200 mm length. A rectangular unit mold can be obtained by cutting to a desired size. In the latter case, the surrounding 4
Although flanges can be provided on all sides and can be molded at once in the form of a unit frame having the above dimensions, a complicated mold must be manufactured. At the construction site, regardless of whether it is a unit form by the extrusion method or a unit form by the injection method, the flanges on the sides are joined together and a plurality of unit forms are connected vertically and horizontally using a C-shaped clip or the like. The operation is the same as in the previous various forms.

[0010]

According to the present invention, the paraffin wax added to the thermoplastic resin and constituting the synthetic resin composition together with the resin is easily formed by melt extrusion or injection. It acts as a kind of “lubricating agent” and not only facilitates the release of the resin composition from an extrusion die or an injection mold, but also when used at a concrete casting site, Paraffin wax functions as one type of “plasticizer”.

[0011] paraffin wax which acts as a plasticizer, crystalline regions and amorphous regions molecular arrangement states, such as in our Keru synthetic resin molecules moldings internal tissue, i.e. altering the internal microstructure of the resin molded article in a preferred direction By
Improves the toughness of concrete formwork made of synthetic resin. In particular, not only the impact resistance at low temperatures but also the torsional strength, which has been conventionally demanded to be improved, is remarkably improved, and the face plate is brought into contact with the face plate by the impact of an external object or the C-shaped clip screwing into the adjacent flange. There is little risk of cracking or breakage of the flange or flange.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment shown in FIGS.
As an example, a concrete form having a width of 600 mm (that is, a unit form) is formed by extruding through a die while mixing about 6% by weight of paraffin wax with polypropylene resin as a main component. That is, 6 parts by weight of the wax was extruded into 94 parts by weight of the resin as a long product (T) while uniformly kneading the inside of the extruder.
It is cut at the cutting line (4) every 0 mm. The thickness of the flat face plate (1) is, for example, 4 mm, which is extremely thin as compared with the thickness of the conventional wood plywood of 12 mm .

[0013] Flanges (2), (2) integrally formed along opposite sides of the face plate (1) as "mold form thickness defining portions".
Has a thickness of about 100 mm, and holes (not shown) for C-shaped clips and the like used for connection to flanges of the same type of adjacent formwork are appropriately perforated after extrusion.

The mold of the second embodiment shown in FIG. 3 is manufactured by supplying a chip obtained by mixing 3% by weight of the paraffin wax to a polyethylene resin to a raw material hopper of an injection molding machine. The size of the face plate (1) in plan view is 600 mm × 1200 mm as in the first embodiment, but its thickness is 3 mm. However, in this example, the face plate
From any of the four sides of (1), a flange (2) as a “mold form thickness defining portion” is provided protruding from the back side, and the face plate (1) has
A number of small recesses in the shape of a hexagonal cylinder with a bottom connected in a honeycomb pattern (3),
(3) are formed so that each bottom is flush with the lower end of the flange. Therefore, in this example, the series of the small concave portions (3) also function as “portion defining the formwork thickness”.

As described above, in this embodiment, the face plate (1) can receive the lateral pressure of the ready-mixed concrete injected between the opposed two forms, on the entire surface of the concrete, and the concrete surface after the casting and hardening is applied. Shows a decorative uneven pattern. Again, each flange (2) may be provided with an appropriate connection hole (not shown).

Although the embodiments which are considered to be representative of the present invention have been described above, the present invention is not necessarily limited to only the structures of the embodiments, but has the constitutional requirements of the present invention and the object of the present invention. Is achieved, and the present invention can be implemented with appropriate modification within a range in which the following effects can be obtained. For example, the shape of the face plate may be triangular, hexagonal, or even circular, and a circular window may be opened at the center of the rectangular face plate, and another formwork having a circular face plate may be fitted into this window. Use,
Various modifications are possible. For the first embodiment,
For example, one or several reinforcing ribs may be protrudingly provided at the center between the two flanges, for example, at the same height and parallel to the flanges.
Furthermore, although the main component of the paraffin wax is a straight-chain saturated hydrocarbon, the paraffin wax may contain a considerable amount of a branched isomer. Since the isomer has a melting point lower than that of the long-chain n-isomer, a hydrocarbon having a value relatively closer to the upper limit in each of the above ranges as the average carbon number and average molecular weight in one molecule. By using a mixture,
The melting point can be kept within the above range.

[0017]

Since the concrete formwork of the present invention is constructed as described above, it is strong in spite of its light weight, and contributes to the improvement of the efficiency of various types of civil engineering work involving concrete placing work. However, it is large. Moreover, since the synthetic resin face plate into which paraffin wax has been kneaded has a very good releasability from the hardened concrete surface, a beautiful concrete surface can be formed and the concrete attached to the face plate can be peeled off. No extra work is required. Another important advantage is that it maintains good flexibility even at low temperatures and thus has excellent durability, and is also advantageous in terms of cost reduction in concrete casting work.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a back side of a mold according to a first embodiment of the present invention.

FIG. 2 is a bottom view showing a state in which the mold is being manufactured.

FIG. 3 is a perspective view showing an upper surface side of a mold according to a second embodiment of the present invention.

[Explanation of symbols]

 (1) Face plate (2) Flange (3) Small recess (4) Cut line (T) Long form before cutting

Claims (1)

(57) [Claims] 1. A face plate (1) serving as a concrete casting surface,
A shape integrally provided with formwork thickness defining portions (2), (2), (3), (3), ... which are provided continuously in a direction substantially perpendicular to the face plate (1). The synthetic resin composition is obtained by uniformly kneading a thermoplastic resin and paraffin wax, and the paraffin wax has an average number of carbon atoms of 20 to 35 per molecule and an average molecular weight of 20 to 35. 300-50
0 as a main component and a melting point of 60-8.
A concrete form made of synthetic resin, which is a hydrocarbon mixture at a temperature within the range of 0 ° C and is contained in the synthetic resin composition in an amount of 1 to 10% by weight.