JPH0615631A - Unevenness forming method to precast concrete sheet - Google Patents

Abstract

PURPOSE:To provide a useful method for forming unevenness on one surface of a thin PC plate to be used favorably as a throwaway concrete shuttering. CONSTITUTION:Concrete 4 is placed within a flat casting concrete shuttering and the top of the concrete 4 is leveled by moving a bed 2. Here aluminum powder is added as a foaming agent, a lid is put over the same and bubbles 71, 72 are allowed to occur on the upper part of the concrete 4. The concrete is solidified under this state and a PC sheet having numerous bubbles 71, 72 on one surface is made. Since high pressure water is applied to the surface of the PC sheet where the foregoing bubbles are allowed to occur, an end part of the bubble 72 which is not opened is opened and made into a recessed part. Most of the recessed parts are formed into a dovetail type. Numerous fine unevenness parts are formed on one surface of the PC sheet by the recessed parts and the recessed parts formed by the bubbles 71 are opened from the very beginning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming unevenness on a precast concrete board (hereinafter abbreviated as PC board), and in particular, it has unevenness on one side of a thin PC board which is preferably used as a discarding mold. To a useful method for forming.

[0002]

2. Description of the Related Art In recent years, thin-walled PC boards are often used as a discarding form for placing concrete, but PC boards made of concrete containing melamine resin (commonly known as HM
The C plate) is preferably used because it can maintain high strength even when formed thin compared to other thin PC plates. When this HMC board is used as a discarding form, since it does not have sufficient adhesion to concrete as it is, normally, bolt-type or wire-type embedded anchors are put in several places and placed concrete is poured. It was prevented from falling off.

[0003]

However, in the above-mentioned method, the HMC plate cannot follow the stress strain or creep due to the shrinkage of concrete or the external force, and the HMC plate peels off at the interface between the HMC plate and the concrete, or Was causing cracks. In addition, the HMC plate is a conventional thin P
Since it is formed to be considerably thinner than the C plate, a useful method for forming unevenness on one entire surface thereof has not been established.

The present invention is for solving such a problem, and is provided on one surface (surface on which concrete is placed) of a thin-walled PC board which is preferably used as a discarding mold.
It is an object to provide a useful method for forming unevenness.

[0005]

In order to achieve the above object, a method for forming irregularities on a PC board of the present invention is a method for forming a surface of a PC board having a large number of bubbles on at least one side thereof. By applying high-pressure water to, the end of the bubble is opened to form a recess.

[0006]

In the method of the present invention, high pressure water is applied to the surface of the PC plate on the side having a large number of bubbles to open the end of the bubble which has not been opened and forms a recess.
As a result, a large number of fine irregularities are formed on one surface of the PC plate, and most of the concave portions formed by opening the ends of the bubbles by applying high-pressure water are formed in a dovetail shape.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 3 are schematic diagrams for explaining this embodiment. Here, unevenness is formed on one surface of the HMC plate by the method of the present invention. First, as shown in FIG. 1 (a), a bed 2 serving as a bottom formwork of a PC board is placed on a table 1 whose top surface is kept horizontal, and a side formwork 3 is placed on the bed 2. ， Fix it. Here, if unevenness is provided inside the side surface form 3, unevenness can be formed on the end surface of the obtained PC plate.

The concrete 4 containing a predetermined amount of melamine resin in the formwork for flat casting thus formed.
By placing and moving the bed 2 on the table 1,
Level the top of the concrete 4. Then, an appropriate amount of aluminum powder 5 is added here as a foaming agent, and is uniformly dispersed on the upper surface of the concrete 4. Next, as shown in FIG. 1B, the upper surface of the concrete 4 is pressed by a lid 6 made of a plate material having low water absorption such as a rubber plate, a plastic plate, and an iron plate,
The aluminum powder 5 is embedded inside the concrete 4.
The lid 6 may have a concave and convex shape formed by sticking an air cap sheet on the inner surface thereof.

As a result, the aluminum powder 5 reacts with the alkali content of the concrete 4 to generate hydrogen, and the hydrogen rises as bubbles to collect bubbles on top of the concrete 4. At this time, it is preferable that the concrete 4 is vibrated by vibrating the bed 2 or the like so as to help the bubbles of the hydrogen to rise, or the bubbles existing in the concrete 4 at the time of pouring.

As shown in a partially enlarged view of FIG. 2, the air bubbles collected in the upper portion of the concrete 4 in this way rise and hit the inner surface of the lid 6 to open the mouth 71.
And a bubble 72 that is not open. In this state,
A PC board can be obtained by curing the concrete 4 under predetermined conditions and removing it from the mold.
A large number of the aforementioned bubbles 71, 72 are included on the side of the concrete 4 that was the upper surface side of the concrete.

The PC plate 41 is put on a water jet or the like, and the high pressure water 8 is applied to the surface on the side where the bubbles 71 and 72 are present, as shown in FIG. The end 72a is opened to form a recess.
Most of the recesses formed in this way are formed in an ant shape. In this way, the bubble 71 that has been a recess from the beginning and the bubble 7 that has been made a recess by applying high-pressure water as described above.
With 2, a large number of fine irregularities are formed on one surface of the PC board 41.

Therefore, as shown in FIG.
The plate 41 is used as a discard form, and concrete 9 is attached to the uneven surface side.
When the concrete is placed, the placed concrete 9 is the PC board 4
Since it hardens in a state where it bites into the concave portion 73 of No. 1, it is possible to improve the bonding force between them. In particular, as for the unevenness formed by this method, since most of the concave portions 73 are dovetails as described above, the concrete 9 and the PC board 41 bite to each other at a high degree, and the PC board 41 is used as a discarding form. High reliability is obtained. That is, by this method, it is possible to form effective unevenness on the surface of a thin PC plate such as an HMC plate.

In the above embodiment, a foaming agent is added to the concrete cast in the mold to cure the concrete in a state where bubbles are generated in the upper part of the concrete, so that a large number of bubbles are formed on one side. Although the PC board having the above is manufactured, the PC board used in the present invention is not limited to this, and may be one prepared by including air bubbles in its entirety like cellular concrete.

[0014]

As described above, according to the method of the present invention, a large number of fine irregularities are formed on one surface of the PC board, and most of the concave portions are formed in a dovetail shape. for that reason,
If unevenness is formed on a thin PC plate such as HMC plate by this method, when HMC plate etc. is used as a discarding form, the bite with concrete is significantly improved compared with the conventional one, and the construction of the member thus constructed is improved. The quality can be significantly improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining an embodiment of the present invention.

FIG. 3 is a schematic diagram for explaining an embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view showing a usage state of the PC board manufactured in this example.

[Explanation of symbols]

 41 PC board 71 Air bubble 72 Air bubble 73 Recess

Claims (1)

[Claims] 1. A precast concrete plate having a large number of bubbles on at least one surface side is exposed to high-pressure water on the surface having the bubbles to open the ends of the bubbles to form recesses. Method for forming irregularities on precast concrete boards.