A plurality of forms 10 are used by joining vertically and laterally so as to define at least one wall of concrete moldings to be molded, for example, the wall of a building. To interconnect the forms 10, a frame-like template 18 is placed on one surface of the plate 16 opposite to the
Guardrail Forming Machine
other surface where said first and second sheets 12, 14 are disposed thereon. The template 18 is fixed to the plate 16 by means of a plurality of rivets 20 penetrating the first sheet 12, second sheet 14, plate 16 and template 18. A secured body of the first and second sheets 12, 14 secured to each other and having an area larger than that of the plate 16 is bent at the peripheral edge of the plate 16 and said peripheral edge is sandwiched between the plate 16 and the template 18. The plate 16 and the template 18 may be made of glass fiber reinforced plastic (FRP) and iron materials for example respectively. The plate 16 may be made of synthetic resin materials.
The concrete to be cast in used under such condition as to contain water of more than necessary amount for hydration of cement, i.e., surplus water so as to reach all the corners of a space defined overall or partially by the first sheet 12 for casting. Also, when the concrete is cast into said space, air in the form of bubbles is mixed in said cast concrete. The surplus water and air degrade the quality of concrete moldings.
While the first sheet 12 permits said surplus water contained in the concrete contacting said sheet to pass therethrough, it can be made of a cloth as shown in the drawing or nonwoven fabric (not shown) which blocks the passage of the concrete. According to the present invention, "the sheet permits the surplus water to pass therethrough, but blocks the passage of the concrete" means as follows: The sheet permits cement grains or other fine particles leaching through unhardened concrete together with said surplus water to pass through the sheet, but blocks the passage of the concrete, i.e., grains containing cement, water necessary for hydration of said cement and aggregates or the like, after the completion of exhausting the surplus water. Said cloth, nonwoven fabric or the like is preferably made of synthetic fiber having high alkali resistance, water resisting property, weather resisting property and relatively high tensile strength.
The second sheet 14 is secured to the first sheet 12 on one surface and secured to the plate 16 on the other surface by way of adhesive 22 such as those made of synthetic resin to permit said surplus water coarser than meshes of the first sheet 12 to impregnate said sheet 14. The second sheet 14 may be constituted of cloth made of synthetic fibers similar to the first sheet 12. In case where the second sheet 14 is made of synthetic fiber and the plate is made of synthetic resin material, either one of the surfaces thereof is fused with heat treatment, and press fitted during the fusion to bond them with each other in lieu of said adhesive. By making th
Downpipe Forming Machinee second sheet 14 of cloth having coarse meshes, i.e., large structural gaps between weft 24a and warp 24b in the embodiment shown may be easily impregnated the second sheet 14 with a great amount of adhesive. This increases adhesion between the plate 16 and the second sheet 14 and thus binding force between the first sheet 12 and the plate 16. Thus, when the form is separated from the concrete by removing the first sheet 12 from the concrete molding, the first sheet 12 may be prevented from exfoliation from the plate 16. The adhesives 22 is desirably allowed to be impregnated up to a half of the thickness T of the second sheet 14.
Dust Shield Forming Machine
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