JP7479766B2 - Mortar pressure-transport hose and mortar pressure-transport method - Google Patents

Description

The present invention relates to a flexible hose for pumping mortar, and also to a method for pumping mortar using the flexible hose.

Mortar, i.e. concrete mortar, is used in the construction of civil engineering/architectures such as buildings, highways, dams, etc. Mortar is pumped into a formwork, where it hardens into a desired shape to become a building or civil engineering structure. When pouring mortar, it is necessary to transport (pump) the mortar, and flexible hoses are sometimes used as part of the pumping route.

Using a flexible hose for the pumping path of mortar increases the flexibility of the pumping path, which is convenient.
Patent Document 1 discloses a technology for a hose for pressure-transporting mortar, in which conductor wires are embedded spirally on both the inner and outer peripheral surfaces of the hose and the conductivity state of these conductors is checked to detect wear or damage to the hose, and it is disclosed that this hose for pressure-transporting mortar makes it possible to efficiently detect wear or damage to the hose.

JP 2010-138991 A

In recent years, high-strength mortar reinforced with fibers has been used in the construction of civil engineering structures and buildings that use mortar. In particular, by using mortar reinforced with metal fibers, especially steel fibers, the strength of the hardened mortar can be significantly increased, resulting in benefits such as the omission of reinforcing bars, the reduction in the cross-section of mortar structures, and the reduction in cracks in the mortar.

However, it has been found that the use of mortar reinforced with steel fibers tends to shorten the lifespan of the flexible hose used for pumping. According to the inventors' research, it has been found that when mortar contains steel fibers, the steel fibers in the mortar penetrate the inner surface of the hose during pumping, which is related to the shortening of the hose's lifespan.

An object of the present invention is to provide a hose for pressure-feeding mortar and a method for pressure- feeding mortar in which metal fibers contained in mortar are less likely to penetrate into the inner peripheral surface of the hose.

After extensive research, the inventor discovered that constructing the inner surface of the hose from a specific resin material would prevent metal fibers from penetrating the mortar, and thus completed the present invention.

The present invention relates to a hose for pressure-feeding mortar having a hose wall made of synthetic resin and a spiral reinforcement embedded in the hose wall, wherein the inner circumferential surface of the hose wall is made of a vinyl chloride resin composition containing a silicone resin or a silicone oil (first invention).

In the first invention, preferably, the hose wall has a multi-layer structure including an inner layer disposed on the innermost circumference of the hose, and the Duro A hardness of the vinyl chloride resin composition constituting the inner layer is 70 degrees or more and 90 degrees or less (second invention). The present invention also relates to a method for pumping mortar containing metal fibers, which pumps mortar containing metal fibers using the mortar pumping hose of the first or second invention (third invention).

According to the mortar pumping hose (first invention) of the present invention and the mortar pumping method (third invention) containing the metal fibers of the present invention, it is possible to prevent the steel fibers from penetrating the mortar. Furthermore, as in the second invention, if the hose wall has a multi-layer structure and the hardness of the resin of the inner layer is set to 70 degrees to 90 degrees in Duro A (measured immediately after pressure application based on JIS K7215), it is possible to more effectively prevent the steel fibers from penetrating the mortar.

1 is a partial cross-sectional view showing the structure of a mortar pressure- transporting hose according to a first embodiment. FIG. FIG. 6 is a partial cross-sectional view showing the structure of a mortar pressure- transporting hose according to a second embodiment

The following describes an embodiment of a hose for pumping mortar containing steel fibers with reference to the drawings. Note that the invention is not limited to the specific embodiment shown below, and can be implemented by modifying the form.

Fig. 1 is a partial cross-sectional view showing the structure of a mortar pressure-feeding hose 1 of the first embodiment. The upper half of the hose from the central axis is shown in cross-section, and the lower half is shown in an external view. The same is true for Fig. 2. The mortar pressure-feeding hose 1 has a hose wall 10 made of synthetic resin and a spiral reinforcement 13 embedded in the hose wall 10. The hose wall 10 is flexible, and contributes to the flexibility of the hose 1.

The spiral reinforcement 13 is made of a material harder than the resin material that makes up the hose wall, and maintains the cylindrical shape of the hose 1 while withstanding the internal pressure during pumping of mortar. The spiral reinforcement 13 can be made of, for example, a resin material (e.g., hard polyvinyl chloride resin) with a Duro A hardness of 85 degrees or more, a metal wire (e.g., hard steel wire, etc.), a resin-coated metal wire (e.g., PVC-coated steel wire, etc.), etc. The spiral reinforcement 13 may be provided in a single spiral shape, or in two or more spiral shapes.

By embedding the spiral reinforcement 13 in the hose wall 10, the spiral reinforcement 13 and the hose wall 10 are firmly integrated, and the pressure resistance of the hose is improved. As in this embodiment, it is preferable that the entire spiral reinforcement 13 is embedded in the hose wall 10, but this is not essential. As in the second embodiment described below, only a portion of the spiral reinforcement may be embedded in the hose wall.

A hose inner peripheral surface 10A of the hose wall 10 is made of a vinyl chloride resin composition containing a silicone resin or silicone oil. Although not essential, in this embodiment, the hose wall 10 has an inner layer 11 and an outer layer 12. That is, the hose wall 10 has a multi-layer structure including the inner layer 11 disposed on the innermost circumference of the hose.
Although not essential, the hose wall 10 is formed in a substantially cylindrical shape.

The vinyl chloride resin composition constituting the hose inner surface 10A contains a silicone resin or a silicone oil. Here, the silicone resin includes a silicone rubber or a silicone resin. The silicone resin is preferably contained in a powder form, so-called silicone powder (silicone rubber powder, silicone resin powder, etc.). The preferred amount of silicone resin or silicone oil is about 3 to 30 parts by weight, more preferably about 5 to 20 parts by weight, per 100 parts by weight of vinyl chloride resin. An example of a vinyl chloride resin composition containing a silicone resin is a vinyl chloride resin composition containing a silicone resin powder, which is sold by Shin-Etsu Polymer Co., Ltd. as a PVC compound in the EXELAST series under the product number SE-855.

The vinyl chloride resin composition constituting the hose inner surface 10A, in this embodiment the vinyl chloride resin composition constituting the inner layer 11, preferably has a hardness of 70 degrees or more and 90 degrees or less in terms of Duro A hardness (measured immediately after pressure application based on JIS K7215). In addition, when the hose wall 10 has a multi-layer structure, it is preferable that the inner layer 11 is harder than the other layers (e.g., the outer layer 12).

The vinyl chloride resin composition that constitutes the hose inner surface 10A may contain additives such as plasticizers, stabilizers, fillers, and antioxidants, as necessary.

The mortar pressure-feeding hose 1 of the first embodiment can be manufactured by a conventionally known hose manufacturing method. That is, a hose forming shaft capable of spirally winding a flexible strip is prepared, and materials to be the inner layer 11, outer layer 12 and spiral reinforcement 13 of the hose wall are extruded or co-extruded in a semi-molten tape or string shape and supplied to the hose forming shaft. These materials are fused together on the hose forming shaft to form a multi-layered hose wall 10 in a cylindrical shape, and the spiral reinforcement 13 is embedded in the hose wall 10, and the mortar pressure-feeding hose 1 is continuously molded.

The mortar pressure-feeding hose 1 of the first embodiment can be used for transporting, i.e., pressure-feeding, mortar. In particular, the mortar pressure-feeding hose 1 of the first embodiment is suitable for pressure-feeding mortar containing metal fibers. In particular, it is suitable for pressure-feeding mortar containing steel fibers that have a high reinforcing effect on mortar. Note that the metal fibers contained in the mortar are not limited to steel fibers, and iron fibers, stainless steel fibers, zinc fibers, etc. can also be used.

The operation and effect of the mortar pressure- feeding hose 1 of the first embodiment will be described.
According to the mortar pumping hose 1 of the first embodiment, the inner peripheral surface of the hose is made of a vinyl chloride resin composition containing silicone resin or silicone oil, so that metal fibers (especially steel fibers) contained in the mortar are less likely to pierce the inner peripheral surface of the hose when pumping mortar.

The details of the mechanism by which the incorporation of silicone resin or silicone oil into the polyvinyl chloride resin composition prevents metal fibers from penetrating are unclear, but it is speculated that the improved slipperiness of the inner circumferential surface 10A of the hose contributes to preventing steel fibers contained in the mortar from penetrating the hose.

If metal fibers penetrate the inner surface of the hose when pumping mortar, other metal fibers will tend to accumulate and become entangled with the penetrated metal fibers. As a result, resistance to pumping mortar increases, and the hose is more likely to be subjected to high pumping pressure. Higher pumping pressure puts more strain on the hose, shortening its lifespan.
In addition, when metal fibers penetrate the inner peripheral surface of the hose, the inner peripheral surface of the hose becomes easily scraped and roughened, and the hose becomes easily worn. When metal fibers penetrate the inner peripheral surface of the hose, the strength and durability of the hose tend to decrease, but if the penetration of metal fibers can be prevented, the deterioration of strength and durability can be prevented.

From the viewpoint of more effectively preventing metal fibers from penetrating the inner peripheral surface of the hose, it is preferable that the hose wall has a multi-layer structure with an inner layer disposed on the innermost circumference of the hose, and that the vinyl chloride resin composition constituting the inner layer has a Duro A hardness (measured immediately after pressurization according to JIS K7215) of 70 degrees or more and 90 degrees or less. By constructing the inner layer from a material with a Duro A hardness of 70 degrees or more and 90 degrees or less, which is a harder material for constructing a hose wall, it is possible to effectively prevent metal fibers from penetrating. Furthermore, by making the hose into a multi-layer structure, it is possible to prevent the hose from becoming rigid by using a softer resin material for the parts other than the inner layer, while at the same time effectively preventing metal fibers from penetrating.

Furthermore, if the mortar pumping hose of the first embodiment is used to pump mortar containing metal fibers, even if the mortar contains metal fibers, particularly steel fibers, the mortar can be pumped while preventing the metal fibers from piercing the inner peripheral surface of the hose. As a result, the mortar can be pumped by the hose for a long period of time.

Example 1
A mortar pressure-feeding hose of Example 1 was manufactured, which corresponds to the hose 1 of the first embodiment shown in Figure 1. The nominal diameter of the hose is φ50 mm, the thickness of the inner layer is 3.5 mm, the thickness of the outer layer is 4.5 mm, the spiral reinforcement has a rectangular cross section of 4.2 mm in the radial direction of the hose and 7.2 mm in the central axis direction, and the pitch is 11 mm. The spiral reinforcement is a hard polyvinyl chloride resin with a Duro A hardness of 90 degrees, the outer layer of the hose wall is a soft polyvinyl chloride resin with a Duro A hardness of 60 degrees, and the inner layer of the hose wall is a soft polyvinyl chloride resin containing silicone powder (Duro A hardness of 80 degrees, manufactured by Shin-Etsu Polymer Co., Ltd.).

Comparative Example
A comparative mortar pressure- feeding hose was produced in the same manner as in Example 1, except that both the inner and outer layers were made of a soft polyvinyl chloride resin composition having a Duro A hardness of 60 degrees.

The hoses of Example 1 and Comparative Example were used to pump mortar containing steel fibers. With the hose of Comparative Example, pumping of mortar became difficult soon after pumping started, and pumping stopped at a hose length of about 10 m. With the hose of Comparative Example, steel fibers pierced the inner circumferential surface of the hose. With the hose of Example 1, pumping of mortar did not stop after pumping started, and mortar could be pumped even with a hose length of 20 m, and it was confirmed that the penetration of steel fibers into the inner circumferential surface of the hose was suppressed. Furthermore, with the hose of Example 1, no extreme wear was observed on the inner circumferential surface of the hose, and it was confirmed that the penetration of steel fibers into the inner circumferential surface of the hose was suppressed.

The invention is not limited to the above-described embodiment, and can be implemented with various modifications. Other embodiments of the invention are described below, but in the following description, the differences from the above-described embodiment will be mainly described, and detailed descriptions of similar parts will be omitted. Furthermore, these embodiments can be implemented by combining parts with each other, or by substituting parts.

Although not essential, the mortar pumping hose 1 may have reinforcing fibers, reinforcing threads or a reinforcing layer, a heat insulating layer, an abrasion resistant layer, an abrasion detection line, etc., on the hose wall, etc. When pumping mortar, it is preferable that the hose 1 has any of reinforcing fibers, reinforcing threads, or a reinforcing layer.

2 shows a mortar pressure-feeding hose 2 according to a second embodiment. In the mortar pressure-feeding hose 2 of this embodiment, the spiral reinforcement 23 is embedded in about half of the outer periphery of the hose wall 20. In this manner, it is not necessary for the entire spiral reinforcement to be embedded in the hose wall, and it is sufficient that at least the inner peripheral portion of the reinforcement is embedded in the hose wall so that the reinforcement and the hose wall are firmly integrated.

In the mortar pumping hose 2 of the second embodiment, the hose wall 20 is a single-layer hose wall made of a single resin composition. In this case, too, if the inner peripheral surface of the hose wall 20 is made of a vinyl chloride resin composition containing a silicone resin or silicone oil, it is possible to prevent metal fibers from piercing the inner peripheral surface of the hose, as in the hose 1 of the first embodiment.

Furthermore, it is preferable that the inner surface of the hose is substantially smooth and cylindrical, and that the inner surface of the hose is substantially free of gaps, steps, ridges, grooves, etc. If the inner surface of the hose is smooth, it is difficult for metal fibers to penetrate it.

The mortar pressure-feeding hose of the above embodiment can be used for pressure-feeding mortar, and is highly industrially useful because it can prevent metal fibers from piercing the hose.

Reference Signs List 1 Mortar pressure- transport hose 10 Hose wall 10A Hose inner peripheral surface 11 Inner layer 12 Outer layer 13 Spiral reinforcement body

Claims (3)

A mortar pressure -feeding hose having a synthetic resin hose wall and a spiral reinforcement body embedded in the hose wall,
The inner circumferential surface of the hose wall is made of a vinyl chloride resin composition containing a silicone resin or a silicone oil.
Hose for pumping mortar. The hose wall is a multi-layer structure having an inner layer disposed on the innermost circumference of the hose;
The vinyl chloride resin composition constituting the inner layer has a Duro A hardness of 70 degrees or more and 90 degrees or less.
The mortar pressure conveying hose according to claim 1. A method for pumping mortar containing metal fibers, comprising pumping mortar containing metal fibers using the hose for pumping mortar according to claim 1 or 2.

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