JPH0752133A - Embedding form made of precast concrete - Google Patents

Abstract

PURPOSE:To enhance the integrality with main body concrete by providing conical projections to the almost entire surface on the side of main body concrete. CONSTITUTION:An embedding form 1 made of precast concrete is formed by densely providing regular quadrangular pyramid shaped projections 2 to the surface of enabedding form concrete 3. The projections 2 are composed of high compression strength cement mortar and the angle formed by the slope and bottom surface of the regular quadrangular pyramid is set to about 45 deg.. The embedding form made of precast concrete can be easily produced by casting the embedding form concrete 3 into a manufacturing form having reinforcing rods arranged thereto and pressing the press form having regular quadrangular recessed parts carved therein to the surface of the embedding form concrete 3 before the start of curing and transferring the recessed parts to the embedding form concrete 3. By this constitution, the integrality with main body concrete can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regular polygonal pyramid shape or a regular polygonal pyramid shape (hereinafter referred to as a cone or a pyramid shape) in which a slope is a flat surface or a curved surface which is convex outwardly on substantially the entire surface of the main body concrete side. (Hereinafter collectively referred to as "). The present invention relates to a precast concrete buried formwork having high integration with a main body concrete provided with a projection.

[0002]

2. Description of the Related Art Precast concrete buried formwork is used in the construction of concrete structures for the purpose of speeding up the construction, labor saving and economic efficiency. It is desired that the unity is as high as possible.

As a measure to meet this demand, unevenness is applied to the surface of the embedded formwork on the main body concrete side by the following method.

(1) After hardening of concrete, chipping or the like is performed to make unevenness.

(2) At the uncured stage of concrete, coarse aggregate is exposed by a method such as sand blasting to form irregularities.

(3) The rough aggregate is transplanted at the uncured stage of the concrete to form irregularities.

(4) Concavities and convexities are provided on the surface of a dedicated mold for producing a concrete-embedded mold, and the irregularities are transferred to the surface of the buried mold.

[0008]

According to the above methods (1) to (3), not only a lot of labor and time are required for the work, but also a precast concrete buried formwork having a constant surface shape is constantly manufactured. It's almost impossible. In the case of the method of (4) above, generally, a smooth dedicated mold for manufacturing is used on the surface on the opposite side of the main body concrete from the viewpoint of the aesthetic appearance of the completed structure. The surface on the concrete side of the main body must be the holding mold side (upper surface side) of the dedicated mold for manufacturing. If a normal one with unevenness is used as this pressing mold, the unevenness is sparse, the area of the concave is much smaller than the area of the convex, and a simple cylinder or prismatic shape with unevenness is used. It can only be manufactured, and its integrity with the main body concrete is poor.

[0009]

DISCLOSURE OF THE INVENTION The present invention is a precast concrete buried formwork in which a cone-shaped projection is provided on substantially the entire surface of the main body concrete side to enhance the integrity with the main body concrete.

In the present invention, a regular polygonal pyramid means a regular triangular pyramid,
It means regular quadrangular pyramid and regular hexagonal pyramid. Regular pyramid, regular pyramid,
This is because the regular hexagonal pyramid has a continuous bottom surface, and the pyramidal protrusions can be continuously provided without a gap therebetween. If the conical protrusions can be continuously provided, the protrusions can be densely provided on substantially the entire surface of the precast concrete embedded formwork surface. It is preferable to provide the protrusions densely on the entire surface if possible, but it is a small size when using a large frame by connecting several small frames to the place corresponding to the end of the holding mold of the dedicated manufacturing frame It is inevitable that protrusions will be missing at places corresponding to the joints of the frame.

The angle between the slope and the bottom of the projection cone is 40 to
It is preferably 50 °. If the slope is a curved surface, the curved surface is assumed to be a flat surface, and the angle between the slope and the bottom is 40 to 50 °.
Is preferred.

The precast concrete buried formwork of the present invention has not only a significantly larger contact area with the main body concrete than the conventional buried formwork having an uneven surface, but also the contact surface faces in various directions. Since the shear stress at the joint can be dispersed in various directions, the shear strength can be greatly improved.

Now, considering the connection between the buried formwork concrete and the main body concrete at the projection, when the slope of the cone is a flat surface, the shear cross-sectional area of the projection sharply increases in inverse proportion to the square of the distance from the bottom surface. Get smaller. On the other hand, the cross-sectional area of the concrete body decreases as it goes from the top to the bottom of the projection, but the extent is much slower than the decrease in the shear cross-sectional area of the projection. Therefore, if the strength of the buried formwork concrete and the strength of the main body concrete are the same, shear failure of the joint will occur on the buried formwork concrete side first, so the shear strength of the concrete structure as a whole will be small. . Therefore, in this case, it is preferable to use a buried form concrete having a strength higher than that of the main body concrete to improve the shear strength of the concrete structure as a whole. When the slope of the pyramid is a curved surface, the degree of strengthening can be relaxed as compared with the case of a flat surface.

When the shape of the cone of the protrusion is a regular polygonal cone, stress is naturally concentrated on the apex. If an obstacle due to this stress concentration is conceivable, a trapezoid with a part of the top cut to sacrifice the contact area to avoid stress concentration.

In the present invention, when the projections are formed directly on the concrete surface when the projections are formed on the buried formwork concrete by the dedicated mold for production, the desired shape is formed due to the influence of the coarse aggregate and the adhesion of the concrete. In some cases, no protrusion can be formed. As a remedy at that time, a cement mortar layer may be provided on the buried form concrete, and the projections may be formed on the cement mortar layer with a dedicated mold for production. If the compressive strength of this cement mortar layer is small, the above-mentioned drawbacks appear. Therefore, it is necessary that the compressive strength of cement mortar be higher than that of both buried form concrete and main body concrete.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a precast concrete buried formwork of the present invention, where (a) is a partial plan view and (b) is a plan view.
Is a partial elevational view. (C) is a partial elevation view in which a cement mortar layer is provided on the buried formwork concrete.

In the precast concrete buried formwork 1, regular pyramidal projections 2 are densely provided on the surface of the buried formwork concrete 3. The angle between the slope and the bottom of the regular quadrangular pyramid is approximately 45 °. In the precast concrete buried formwork 1, the buried formwork concrete 3 is placed in the manufacturing formwork in which the reinforcing bars (not shown) are arranged, and before the hardening starts, the surface of the buried formwork concrete 3 is squared. It is easily manufactured by pressing a pressing mold having a pyramidal depression and transferring the irregularities to the embedded mold concrete 3.

As shown in (c), when the cement mortar layer 4 is provided on the buried form concrete 3, it becomes easy to form the protrusion 2 by the pressing form. In this case, after the embedded formwork concrete 3 has been cast, a high compressive strength cement mortar layer 4 is cast on it and the pressing formwork is pressed against the cement mortar layer 4 before hardening begins.

FIG. 2 is a partial plan view showing a precast concrete buried formwork 1 in which projections 2 of another shape are densely provided. In the example of FIG. 2A, the regular quadrangular pyramidal protrusions 2 are densely provided on the surface, and in the example of FIG. 2B, the regular hexagonal pyramidal protrusions 2 are densely provided on the surface. In any case, the angle between the slope and the bottom of the cone is approximately 45 °.

[0021]

Since the projection shape is a regular polygonal pyramid, the bottom surface is continuous, and projections can be continuously provided without a gap between them, and the surface of the precast concrete embedded formwork and the main body concrete It is possible to increase the contact area with and improve the integrity of the two. Further, since the contact surfaces face in various directions, the shear stress at the joint can be dispersed in various directions, so that the shear strength can be greatly improved.

[Brief description of drawings]

FIG. 1 shows an example of a precast concrete buried formwork of the present invention, in which (a) is a partial plan view, and (b) and (c) are partial elevation views.

FIG. 2 is a partial plan view showing another example of the precast concrete buried formwork of the present invention.

[Explanation of symbols]

1 ・ ・ Precast concrete buried formwork, 2 ・ ・ Projection, 3 ・ ・ Buried formwork concrete, 4 ・ ・ High compressive strength cement mortar layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Shinbo 2-19-1 Tobita-Su, Chofu-shi, Tokyo Kashima Construction Co., Ltd. Technical Research Institute

Claims (4)

[Claims] 1. An embedded formwork made of precast concrete, characterized in that a projection having a regular polygonal pyramid shape or a regular polygonal pyramid shape is provided on substantially the entire inner surface. 2. An embedded mold made of precast concrete, characterized in that a projection having a regular polygonal pyramid shape or a regular polygonal pyramid pyramid having an inclined surface which is not a flat surface but a convex curved surface is provided on substantially the entire inner surface. frame. 3. The precast concrete buried formwork according to claim 1 or 2, which is manufactured by using concrete having a compressive strength of 1.5 times or more the compressive strength of the main body concrete. 4. The precast concrete buried formwork according to claim 1, wherein the material of the projection is cement mortar having a higher compressive strength than both the buried formwork concrete and the main body concrete.