JPH0616796U - Mortar / concrete pressure hose - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a mortar-concrete pressure-feeding hose having excellent wear resistance and transportability. [Structure] A hose 1 having an innermost layer 2 and a reinforcing layer 5, the innermost layer 2 being a thermoplastic polyurethane of JIS hardness A scale 75 to 95 to which 0.2 to 2.0 parts by weight of a lubricant is added. The molded hose was a mortar-concrete pumping hose in which the lengthwise and circumferential elongation of the entire hose 1 including the reinforcing layer 5 was 4% or less at a working pressure of 7 kg / cm ² .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hose for pressure-feeding mortar concrete used in a mortar-concrete spraying method, and more particularly to a hose that exhibits excellent wear resistance and transportability for high-viscosity mortar concrete.

[0002]

[Prior art]

 There are various types of mortar concrete used in this mortar-concrete spraying method, but recently developed materials are attracting attention because they do not slip and do not require formwork. This material is a high-viscosity mortar concrete with a large amount of cement and a minimum amount of water, and it is sprayed to the construction surface at high speed by compressed air and densely compressed to form a very dense and strong construction body. Is.

This high-viscosity mortar concrete is introduced into a blowing device connected with compressed air by an air compressor, and the mortar concrete injected into the blowing device is sent with compressed air to a lining construction site through a hose and a nozzle tip. Eject from the edge.

By the way, since high-viscosity mortar / concrete pumped in the hose contains a large amount of cement and contains a minimum amount of water, the inner surface of the hose decreases due to wear. Therefore, the hose is often replaced as a consumable item.

Conventionally, a rubber hose has been used as this type of hose. This rubber hose is composed of an inner layer of compounded rubber in consideration of abrasion resistance, a fiber reinforced layer, and an outer layer of rubber or synthetic resin.

[0006]

[Problems to be solved by the device]

 However, even in the inner layer of the compounded rubber in consideration of abrasion resistance, abrasion has progressed, and there is a problem that durability must be changed in a short time, resulting in poor durability. Therefore, if the inner layer is thickened and the wear dimension is taken into consideration, it becomes a thick hose and becomes heavy and causes problems in handling. In addition, there is a problem that mortar and concrete are likely to adhere to the inner layer of the compounded rubber, and the transport distance is short, so that the transportability is poor.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a mortar-concrete pumping hose having excellent durability and transportability.

[0008]

[Means for Solving the Problems]

In order to achieve the above object, the mortar / concrete pumping hose according to the present invention is a hose having an innermost layer and a reinforcing layer, and the innermost layer contains 0.2 to 2.0 parts by weight of a lubricant. It was molded from the added thermoplastic polyurethane of JIS hardness A scale 75 to 95, and the elongation of the entire hose including the reinforcing layer in the length direction and the circumferential direction was 4% or less at the working pressure of 7 kg / cm ² . It is characterized by that.

[0009]

[Action]

 The thermoplastic polyurethane forming the innermost layer is originally excellent in wear resistance, has a good balance of strength and elongation, and can contain a considerable amount of lubricant. When a lubricant is added, the coefficient of friction on the surface of the innermost layer is reduced and wear resistance and transportability are improved. The amount of lubricant added is 0. If the amount is less than 2 parts by weight, the improvement of the abrasion resistance is insufficient, and if it exceeds 2.0 parts by weight, the decrease in the abrasion resistance due to the weakening of the strength becomes conspicuous. Moreover, the effect of the lubricant is recognized in a wide range of 75 to 95 of JIS hardness A scale of thermoplastic polyurethane.

When the total length of the hose including the reinforcing layer in the lengthwise direction and the circumferential direction is 4% or less at a working pressure of 7 kg / cm ² , the innermost layer is less likely to be stressed when the hose is bent. The elastic force does not decrease, and it is less likely to be damaged even if the sand contained in the mortar or concrete being pumped collides with the innermost layer surface of the curved portion.

[0011]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a hose of the present invention, and FIG. 2 is a development view of a partial cross section of the hose.

In FIGS. 1 and 2, the hose 1 has a three-layer structure including an inner layer 4 including an innermost layer 2 and an adhesive layer 3, a reinforcing layer 5, and an outer layer 6. This three-layer structure itself is generally used, but the material used for the innermost layer 2 and the reinforcing layer 5 that keeps the elongation of the entire hose below a specific value are different from conventional ones, and high pressure mortar, concrete, etc. The structure is suitable for.

The innermost layer 2 is made of thermoplastic polyurethane. Thermoplastic polyurethane is a type of thermoplastic elastomer that exhibits the same mechanical behavior as ordinary rubber at 50 ° C or lower, but it softens and can be molded at 100 ° C or higher, and is extruded into a tubular shape. To mold. Polyurethane has excellent mechanical properties such as abrasion resistance, high elongation and flexibility, and has good compatibility with lubricants.

In the hose of the present invention, a large amount of 0.2 to 2 parts by weight of lubricant is added to the thermoplastic polyurethane of the innermost layer 2 to further reduce the friction resistance. As the lubricant, general ones such as C _{12 to} C ₃₀ carbohydrates, fatty acids, esters and synthetic waxes, metal soaps of C _{12 to} C ₃₀ fatty acids, C _{12 to} C ₃₀ fatty alcohols, polyhydric alcohols and partial esters are used. It can be used. In this embodiment, a mixture of fatty acid amide type and ester type is used.

The effect of adding a large amount of lubricant to the thermoplastic polyurethane will be described with reference to the graph of FIG. 3 showing the relationship between the lubricant addition amount and the wear amount. The amount of wear was measured with an Akron wear tester specified in BS903 (British Standard No.903). The amount of wear was measured by pressing a disc-shaped test piece against a friction disc at an angle of 15 ° and a load of 6 pounds, and performing 500 times of preliminary shearing and 1000 times of test shearing. As shown in the figure, the amount of wear rapidly increases in the region where the lubricant is less than 0.2 parts by weight and in the region where the lubricant exceeds 2.0 parts by weight. When it exceeds 2.0 parts by weight, it is considered that the wear amount is increased because the mechanical properties of the thermoplastic polyurethane deteriorate. In addition, the amount of wear is relatively stable in the area of 0.2 to 2.0 parts by weight.

The thermoplastic polyurethane is usually used in JIS hardness A scale of 75 to 95. Table 1 shows the effect of the lubricant in this hardness range.

[0017]

[Table 1]

According to Table 1, the amount of the lubricant containing 1 part by weight of the lubricant is relatively less than that of the lubricant without pear, and the effect of the lubricant is recognized in a wide range of hardness 75 to 95. Thermoplastic polyurethane with a hardness of 95 or higher cannot be used for hoses because it is not flexible. Note that the wear amount in Table 1 is different from that in FIG. 3 and is measured by a Taber wear machine specified in JIS7311.

Returning to FIG. 1 and FIG. 2, the adhesive layer 3 is for ensuring the close contact between the innermost layer 2 and the reinforcing layer 5. That is, since the innermost layer 2 has a small friction coefficient, the reinforcing layer 5 cannot be directly adhered to the innermost layer 2. The adhesive layer 3 is made of thermoplastic polyurethane, polyamide or polyester without lubricant.

In FIG. 1 and FIG. 2, the reinforcing layer 5 has a warp yarn 11 and a first weft yarn 12 and a second weft yarn 13 alternately formed into a double weave design. A polyester spun yarn is used as the warp yarn 11, and a nylon monofilament is wound around the first weft yarn 12 in a spiral shape. When the working pressure is 7 kg / cm ² , the hose 1 has a longitudinal and circumferential extension of 4 mm. % Or less. The outer layer 6 is provided to ensure that the outer surface of the hose can be sealed without the irregularities of the first weft thread 12 of the reinforcing layer 5 appearing on the surface and for protection from physical damage, and ordinary polyvinyl chloride or the like is used.

Next, concrete examples of the present invention and comparative examples will be described in comparison with Table 2.

[0022]

[Table 2]

In Table 2, the hose of the present invention is the innermost layer of thermoplastic polyurethane (JIS A scale hardness 81,2 mm thickness, lubricant 1%) and the thermoplastic polyurethane (JISA scale hardness 70,0. Inner layer consisting of an adhesive layer of 5 mm thickness, no lubricant, warp yarn of polyester spun yarn (20 count / 8 × 2 × 239), nylon monofilament (φ2.5 mm) and polyester filament yarn (1500 d / 10 × 10 cm) It has a dimension of reinforcement layer of alternate weft double weave structure and outer layer of polyvinyl chloride (2mm thickness), inner diameter 42mm, outer diameter 57mm, weight 1.5kg per 1m. Is. Comparative Example 1 uses polyester spun yarn as the warp yarn as in the case of the present invention, but the number of warp yarns is reduced to 20 count / 8 × 2 × 200 yarns, and the number of warp yarns is also reduced to 21 pitches. The other points are the same, except that the elongation in the length direction is 5% or more compared to 2.2% in the example of the present invention. The hose of Comparative Example 2 has an inner layer of chloroprene rubber, a reinforcing layer formed by weaving vinylon yarn in a tape shape and wound around the inner layer, and an outer layer of chloroprene rubber, and has an inner diameter of 42 mm, which is the same as the present invention. However, the outer diameter is as large as 62 mm, and the weight is as heavy as 2.2 kg per 1 m.

Durability tests were conducted on the examples of the present invention, Comparative Example 1 and Comparative Example 2 described above. The hose was arranged so as to have one or more bends, and mortar and concrete were pressure-fed at 7 kg / cm ² , and the pressure-feeding volume (m ³ ) until the innermost layer was damaged and pressure-feeding became impossible was measured. The pumping volume during mortar pumping is 2000 m ³ or more in the present invention example, which is twice the 1000 m ³ of Comparative Example 2 even though the innermost layer is thin. In Comparative Example 1, the elongation in the length direction was large, the stress acted on the innermost layer at the bent portion of the hose, and when the sand contained in the mortar collided, it was easily damaged and could not be pumped at 300 m ³ . . However, if the elongation in the lengthwise direction is set to 4% or less for the entire hose, the durability of Comparative Example 2 or higher is exhibited. Also, if the elongation in the circumferential direction exceeds 4%, stress acts on the innermost layer and is easily damaged, so the elongation in the circumferential direction must be 4% or less. It should be noted that concrete has improved durability like mortar.

The transportability test is a measurement of the distance (m) at which pressure can be fed. In the present invention example, compared with Comparative Example 2, a distance of more than twice the conventional method of mortar concrete is used. With the above-mentioned high-viscosity mortar concrete, it is possible to send a distance more than four times.

In the height difference test, the height at which pressure can be fed is measured in terms of height difference (m). In this invention example, the mortar / concrete of the conventional method raises the height by a factor of 2 or more compared to the comparative example 2. It is possible to raise the height to 13 times or more with the above-mentioned high-viscosity mortar concrete. Thus, in the case of high-viscosity mortar-concrete with a large amount of cement and a minimum amount of water, the difference is more noticeable than with conventional rubber hoses.

[0027]

[Effect of device]

According to the present invention having the above-mentioned structure, the innermost layer of the hose is formed of thermoplastic polyurethane of JIS hardness A scale 75 to 95 with 0.2 to 2.0 parts by weight of lubricant added, and Durability increases as the friction coefficient decreases and the amount of wear decreases, and the thickness can be reduced as the durability increases, making it lighter and easier to handle than rubber hoses. In addition, the low coefficient of friction on the surface of the innermost layer makes it difficult for mortar and concrete to adhere, improving the transportability, and improving the transportability can greatly extend the transport distance. In addition, the lengthwise and circumferential elongation of the entire hose including the reinforcement layer was set to 4% or less at a working pressure of 7 kg / cm ² , so the innermost layer is less likely to receive stress and is damaged by tearing. Durable and durability is not impaired. As a result of the above, the hose replacement period will be longer, the handling will be good, and long-distance transportation will be possible, making the hose suitable for spraying work.

[Brief description of drawings]

FIG. 1 is a perspective view showing a hose of the present invention.

FIG. 2 is a development view of a partial cross section of a hose.

FIG. 3 is a graph showing the relationship between the amount of lubricant added and the amount of wear.

[Explanation of symbols]

 1 hose 2 innermost layer 5 reinforcement layer

Claims (1)

[Scope of utility model registration request] 1. A hose having an innermost layer and a reinforcing layer, wherein the innermost layer is J containing 0.2 to 2.0 parts by weight of a lubricant.
It was molded from thermoplastic polyurethane having an IS hardness A scale of 75 to 95, and the elongation in the lengthwise direction and the circumferential direction of the entire hose including the reinforcing layer was 4% or less at a working pressure of 7 kg / cm ^2. Characteristic mortar / concrete hose.