JPS63255422A - Spraying work of concrete and metal net form therefor - Google Patents

Abstract

PURPOSE:To lessen the rebound of aggregates by a method in which the lower mesh size of the metal net of a metal net formwork is made greater than the upper mesh size, and concrete is sprayed into the formwork. CONSTITUTION:A metal net formwork 1 whose mesh size is increased toward the lower side is set on the ground surface, and concrete is sprayed into the space between the formworks 1. Aggregates which rebound from the ground surface can thus be directed through the mesh of the metal net to the outside.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method of manufacturing a structure by spraying concrete or mortar (hereinafter referred to as "concrete etc.") inside a wire mesh formwork erected on a slope. , relates to the wire mesh formwork used in its construction.

<Conventional technology> There is a construction method that uses wire mesh formwork instead of wood or metal formwork.

For example, as shown in Fig. 5, the construction method involves spraying concrete c into a space surrounded by wire mesh formwork M to form a slope.

<Problems with conventional construction methods> Compared to construction methods in which concrete is poured into formwork,
A problem with the spraying method is material rebound. − During spraying, the concrete aggregate that is blown out with compressed air initially hits the ground and bounces off.
It easily adheres to the inside of the wire mesh.

If such bounced concrete is not packed tightly in the formwork, the aggregate lacking cement content will be concentrated in that area, making it impossible to obtain good concrete.

In that case, if the openings of the wire mesh were made larger, the rebounded aggregate would more easily escape to the outside and would be less likely to stay inside the formwork.

However, if this happens, too much aggregate and mortar will escape to the outside, resulting in an extremely poor surface finish of the completed concrete structure.

OBJECTS OF THE INVENTION The inventor of the present invention studied the mechanism of spraying on site in order to reduce the amount of rebound in the above-mentioned spraying method.

As a result, the rebound of aggregate is particularly high at the beginning of spraying when the concrete hits the ground directly, and immediately after that when the thickness of the concrete is thin. It was found that it was absorbed into the concrete, reducing the amount of rebound.

The present invention was developed from this point of view, and the present invention allows the rebounding aggregate to escape to the outside of the formwork at an early stage, and once the rebound of the aggregate decreases, it is possible to create a concrete with a clean finish. The purpose is to provide a spraying method such as this and formwork used for its construction.

Structure of the Present Invention> Next, an embodiment of the construction method of the present invention will be described, starting with the wire mesh formwork used.

B. Shape of formwork The formwork used in the construction method of the present invention is a wire mesh, as described above, and is particularly characterized by the size of its mesh.

That is, as shown in FIG. 1, the wire mesh formwork 1 is characterized in that the upper mesh dimension L2 and the lower mesh dimension L1 are not the same but different.

Exit> Below the wire mesh formwork Usually, the wire mesh formwork 1 is used standing almost vertically on the ground.

When the wire mesh formwork 1 is erected in this manner, the mesh size (LL in FIG. 1) is formed to be particularly large in the lower part.

Here, forming the size of the eyes to be large is a relative expression compared to the size of the eyes above the wire mesh.

Kuha〉Dimensions of the upper part of the wire mesh formwork The size of the upper openings of the wire mesh formwork 1 (L2> in Fig. 1) uses a wire mesh formwork whose opening size is smaller than the lower dimension of the wire mesh.

That is, in a single piece of wire mesh, the size of the mesh is wider as it goes down, and narrower as it goes up.

However, the distance between the meshes may be changed gradually and continuously in one wire mesh, or it may be changed stepwise and discontinuously.

Construction method of the present invention> Next, the construction method of the present invention will be explained.

I> Installation of the wire mesh formwork As described above, the wire mesh formwork 1 in which the mesh size of the wire mesh changes is installed on the ground.

In this case, as described above, the part of the wire mesh with larger mesh size is located below the wire mesh formwork 1, and the part with smaller mesh size is located above.

Entrance> Spraying of concrete Concrete and mortar are sprayed between the wire mesh forms 1 set on the ground.

Kuha〉Rebounding of concrete (Fig. 2) Since concrete hits the ground directly at first, there is a high chance that the aggregate will bounce back without adhering to the ground.

In this way, when the rate of rebound is high, the spacing between the meshes of the wire mesh is large, so the rebounded aggregate is more likely to fly out from the mesh spacing than to adhere to the inside of the wire mesh.

Therefore, the concrete aggregate that bounces back adheres to the inside of the formwork, resulting in the formation of ``boiled'' concrete.

However, as the spraying of concrete progresses, the thickness of the concrete layer increases, and the adhesion rate of aggregate gradually improves (Figure 3). (Figure 4) When the thickness of concrete exceeds a certain level, aggregate adhesion becomes better.

Therefore, there is no need to let it escape to the outside, and the gap between the meshes of the wire mesh form 1 may be small.

Furthermore, if the mesh size of the wire mesh is small, the concrete sprayed inside the formwork will escape to the outside.

In other words, the concrete is densely packed (to put it in the extreme, it is closely packed in a state similar to that when a plate-shaped formwork is used), so a good finished concrete surface can be obtained.

Effects of the Present Invention B. As described above, the present invention does not make the mesh size of the wire mesh form constant, but increases the size of the lower mesh near the ground.

Therefore, at the start of spraying when concrete adhesion is not good, rebounding aggregate is allowed to escape from between the meshes of the wire mesh to the outside, thereby preventing aggregate from adhering to the inside of the formwork.

Therefore, it is possible to prevent the occurrence of concrete in a "boiled" state.

On the other hand, the openings above the wire mesh formwork are made smaller.

Therefore, in the upper part of the formwork where there is no need to consider the problem of bounce back, it is possible to sufficiently fill the inside of the formwork without allowing the aggregate to escape to the outside.

Therefore, above the formwork, it is possible to obtain compact, good-quality concrete that is well pressurized and has great durability.

[Brief explanation of drawings]

Fig. 1 Side views 2 to 4 of an embodiment of the wire mesh formwork of the present invention
Figure: Explanatory diagram of construction status

Claims (1)

[Claims] 1) In a method of manufacturing a structure by forming a formwork with a wire mesh set up on the ground or the like and spraying concrete or the like into the inside of the formwork, the mesh of the wire mesh below the wire mesh formwork is A method of spraying concrete, etc. in which the dimensions of the wire mesh formwork are formed to be larger than the mesh size of the wire mesh above the wire mesh formwork, and concrete, etc. is sprayed into the inside of the wire mesh formwork. A wire mesh formwork used in a method of manufacturing structures by spraying concrete, etc. inside the formwork, in which the mesh size of the lower wire mesh is larger than the mesh size of the upper wire mesh. Wire mesh formwork, characterized by forming