JP2021063562A - Concrete force-feed pipe - Google Patents

Abstract

To provide a concrete force-feed pipe that does not include a metal pipe, has excellent force-feed performance, is lightweight and excellent in handleability.SOLUTION: A concrete force-feed pipe not including a metal pipe in at least the innermost layer and outermost layer includes a helical male threaded groove or circumferential groove at outer peripheral surfaces in both end parts of a cylindrical body at least whose innermost layer and outermost layer are made of a resin.SELECTED DRAWING: Figure 1

Description

The present invention relates to a concrete pumping pipe.

Fresh concrete before solidification (hereinafter, also simply referred to as "concrete") is a mixture of cement, water, fine aggregate, coarse aggregate and admixtures added as needed, and has liquid properties and solid properties. It also has properties. At the time of pumping, the fresh concrete forms a solid stopper in the steel pipe and is pumped while causing friction with the inner wall of the pipe. At this time, the coarse aggregate is mainly located in the center of the steel pipe, mainly water and cement paste are located on the inner wall side of the steel pipe, and water and the like located on the inner wall side buffer the frictional resistance generated during pumping. While pumping progresses. The pumping property of concrete differs depending on the type and the like. For example, those with high viscosity such as low water content have high frictional resistance and lead to blockage of steel pipes, and those with high water content tend to separate solids and liquids easily, causing blockage of steel pipes and deterioration of the quality of pumped concrete. Become.

Generally, a steel pipe is used for pumping fresh concrete (see, for example, Patent Document 1). The steel pipes are connected by joints as needed, and fresh concrete is pumped to any casting location. A straight steel pipe has a length of about 1, 2, or 3 m, and the higher the pressure resistance performance of the steel pipe, the thicker and heavier the pipe wall. For example, in the case of a 3 m steel pipe for high pressure, the weight is about 65 kg. Therefore, it is necessary for a plurality of people to handle one steel pipe at a construction site.

JP-A-2019-085741

If it becomes possible to replace such steel pipes with resin pipes other than metal pipes, it will be easier to prepare concrete pumping pipe facilities at construction sites, and it is possible to expect an overall improvement in work efficiency. Become. However, with a concrete pumping pipe that does not have a metal pipe, it is difficult to realize a pumping pipe that has pressure resistance that can pump heavy fresh concrete and that can withstand wear during pumping of fresh concrete. Was thought to be.

The present invention has been made in view of the above problems, and provides a concrete pumping pipe that does not have a metal pipe, has excellent pumping performance, is light, and has excellent handleability. With the goal.

The present inventors have diligently studied to solve the above problems. As a result, they have found that the above problems can be solved by using a cylindrical body of ultra-high molecular weight polyethylene and having a concrete pumping pipe having a predetermined structure at the end, and have completed the present invention.

That is, the present invention is as follows.
[1]
A concrete pumping pipe that does not have metal pipes in at least the innermost and outermost layers.
At least the innermost layer and the outermost layer have spiral male screw grooves or circumferential grooves on the outer peripheral surfaces of both ends of a cylinder made of resin.
Concrete pumping pipe.
[2]
The maximum outer diameter R of the cylindrical body is 100 to 250 mm, and the cylinder has a maximum outer diameter R of 100 to 250 mm.
The inner diameter r of the cylindrical body is 70 to 210 mm, and the inner diameter r is 70 to 210 mm.
The thickness (Rr) / 2 of the cylinder is 5 to 20 mm.
The concrete pumping pipe according to [1].
[3]
The total length Lw of the cylindrical body is 0.3 to 4 m.
The concrete pumping pipe according to [1] or [2].
[4]
The pitch of the male screw groove is 3 to 10 mm.
The concrete pumping pipe according to any one of [1] to [3].
[5]
'And _2, the ratio R of the inner diameter r' maximum outer diameter R of the flange to be formed between the end face and the circumferential groove of the cylindrical body ₂ / r is a 1.1 to 1.4,
The concrete pumping pipe according to any one of [1] to [3].
[6]
The coefficient of kinetic friction on the inner surface of the cylinder is 0.07 to 0.15.
The concrete pumping pipe according to any one of [1] to [5].
[7]
The amount of wear of the cylindrical body by the sand slurry wear method is 10 mg or less.
The concrete pumping pipe according to any one of [1] to [6].
[8]
The resin contains ultra high molecular weight polyethylene.
The concrete pumping pipe according to any one of [1] to [7].
[9]
The viscosity average molecular weight of the ultra-high molecular weight polyethylene contained in the resin is 10 × 10 ⁴ or more and 1000 × 10 ⁴ or less.
The concrete pumping pipe according to any one of [1] to [8].
[10]
The cylinder further contains an ultraviolet absorber and
The content of the ultraviolet absorber is 0.01 to 10% by mass with respect to the total amount of the cylinder.
The concrete pumping pipe according to any one of [1] to [9].

According to the present invention, it is possible to provide a concrete pumping pipe which does not have a metal pipe in at least the innermost layer and the outermost layer, has excellent pumping performance, is light, and has excellent handleability.

It is sectional drawing which shows the state which connected the concrete pumping pipe of this embodiment. It is another cross-sectional view which shows the state which connected the concrete pumping pipe of this embodiment.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited thereto, and various modifications can be made without departing from the gist thereof. Is.

[Concrete pumping pipe]
The concrete pumping pipe of the present embodiment is a concrete pumping pipe having no metal pipes in at least the innermost layer and the outermost layer, and has a spiral shape on the outer peripheral surfaces of both ends of a cylinder in which at least the innermost layer and the outermost layer are made of resin. Has a male screw groove or a circumferential groove.

Conventionally, metal pipes such as steel pipes have been used for pumping concrete. It is presumed that this is because the concrete to be pumped is heavy and a certain amount of pressure is required for pumping, so it is considered that a metal pipe is suitable for safe pumping.

However, it has become clear that metal pipes are not suitable for pumping concrete. For example, each metal pipe is heavy and must be handled with care so that multiple workers do not cause an accident. Therefore, there are problems in terms of work safety and on-site work man-hours.

In addition, since the coefficient of dynamic friction between the metal pipe and concrete is relatively high, concrete is usually sent to the metal pipe using a postponing material, but the amount of waste material of the postponing material is large, and the man-hours for using the postponing material can be reduced. Moreover, it is not possible to reduce the cost of disposing of a large amount of postponed material. In addition, due to the high coefficient of dynamic friction, the concrete components are separated during pumping, and the concrete composition discharged from the outlet of the pumping pipe is liable to fluctuate. If such fluctuations occur, the strength of the building will be greatly affected, and the concrete whose composition has fluctuated must be discarded, which further increases the disposal cost.

Furthermore, since it is not possible to visually recognize the inside of the metal pipe, it is not possible to immediately confirm to what position the concrete has reached the concrete pumping pipe, and the concrete is clogged and blocked in the middle of the concrete pumping pipe. I can't notice that it's happening. If such a blockage occurs, an accident may occur due to the rupture of the concrete pumping pipe, and the concrete pumping pipe that has been arranged with man-hours must be discarded and rearranged, which may significantly delay the work. Further, the rupture of the metal pipe when a blockage or the like occurs suddenly occurs at an unexpected position, which also increases the risk of work.

On the other hand, the concrete pumping pipe of the present embodiment is not a concrete pumping pipe made of a metal pipe such as a conventional steel pipe, but a resin cylinder having predetermined characteristics at least in the innermost layer and the outermost layer is used. By not providing metal pipes such as steel pipes in at least the innermost layer and the outermost layer, we have realized a concrete pumping pipe that is lighter and can be handled more safely at the work site, unlike concrete pumping pipes that are heavy and have problems in handling. can do.

Further, the concrete pumping pipe of the present embodiment has a desired coefficient of dynamic friction, so that it is not necessary to use a postponing material. Therefore, the process itself of using the postponed material can be reduced, and the use and disposal cost of the postponed material can be significantly reduced. In addition, it is possible to suppress the separation of concrete components during pumping, and it is possible to significantly reduce the cost of discarding concrete having a variable composition.

Moreover, in the present embodiment, by using a cylindrical body made of resin, it is possible to secure the visibility of the contents in the cylindrical body. As a result, even if the concrete is clogged in the middle of the concrete pumping pipe, it is possible to quickly confirm the blockage and suppress a rupture accident. Moreover, when the internal pressure is high, the resin cylinder swells outward to the extent that it can be visually recognized before it breaks. As a result, the on-site worker can immediately recognize the position where the explosion may occur, and can evacuate appropriately. Hereinafter, the concrete pumping pipe of the present embodiment will be described in detail.

FIG. 1 shows, as an example, a cross-sectional view of a state in which the concrete pumping pipe of the present embodiment is connected. The concrete pumping pipe 10 has a cylindrical body 1 made of resin, and has spiral male screw grooves 4 at both ends thereof for being connected by a joint 3 via a coupling 2. Here, the coupling 2 includes a circumferential groove 5 for fitting the joint 3 and a spiral female screw groove 6 for screwing with the spiral male screw grooves 4 at both ends of the cylindrical body 1. Has. By providing such a male screw groove 4 and connecting the coupling 2, the joint 3 used in the conventional steel pipe can be diverted.

Here, the pitch of the male screw groove 4 is preferably 3 to 10 mm, more preferably 3 to 9 mm, and further preferably 3 to 8 mm. When the pitch of the male screw groove 4 is within the above range, the strength (pressure resistance) of the screwed portion between the coupling 2 and the cylindrical body 1 is improved, and the liquid leakage in the screwed portion tends to be further suppressed. is there.

Further, FIG. 2 shows, as another example, a cross-sectional view of a state in which the concrete pumping pipe of the present embodiment is connected. The concrete pumping pipe 10 in FIG. 2 has a cylindrical body 1 made of resin, and has circumferential grooves 7 at both ends thereof for joining with joints 3. More specifically, the flange 8 is formed by the circumferential groove 7, and the concrete pumping pipe 10 is connected by the joint 3 using the flange 8. By providing such a circumferential groove 7, the joint 3 used in the conventional steel pipe can be diverted.

'And _2, the ratio R of the internal diameter r' maximum outer diameter R of the flange 9 formed between the end face and the circumferential groove 8 of the cylinder 1 ₂ / r is preferably at 1.1 to 1.4 .. By the ratio R _'2 / r is within the above range improves the mechanical strength of the two ends of the cylindrical body 1, destruction of the end portion is more hardly occurs trend.

The concrete pumping pipe 10 of the present embodiment does not have a metal pipe at least in the innermost layer and the outermost layer, and by using a cylindrical body in which at least the innermost layer and the outermost layer are made of resin, the contents in the cylindrical body during use. It is also possible to ensure the visibility of (concrete).

(Cylinder made of resin)
Examples of the resin constituting the cylindrical body made of the resin include a thermoplastic resin and a thermosetting resin. Further, an additive such as an ultraviolet absorber may be added to the resin.

The thermoplastic resin is not particularly limited, and is, for example, a nylon resin such as a polyolefin resin, a polyester resin, a polyarylate, or a monomer cast nylon, a liquid crystal polyester, a polyvinyl chloride, a polyvinyl alcohol, an ethylene vinyl acetate, a polystyrene, or an acrylonitrile. Examples thereof include −butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, polymethyl methacrylate, polyamide resin, polyacetal, polycarbonate, fluororesin, polyether ether ketone, polyether sulfone, and polyphenylene sulfide. ..

The thermosetting resin is not particularly limited, and examples thereof include phenol resin, urea resin, melamine resin, allyl resin, and epoxy resin.

Among these, a thermoplastic resin is preferable from the viewpoint of shapeability, secondary processability and the like. Further, among the thermoplastic resins, polyolefin resins typified by polyethylene and polypropylene are preferable because they are inexpensive, have excellent chemical resistance, are excellent in processability, and have low hygroscopicity and water absorption of the material. ..

The polyolefin-based resin is not particularly limited, but is, for example, a homopolymer of ethylene; a copolymer of ethylene and one or more α-olefins such as propylene, butene-1, hexene-1, and octene-1; Copolymer of ethylene with vinyl acetate, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, etc .; homopolymer of propylene; one or more α-olefins such as propylene and ethylene, butene-1 And the copolymer with.

Among polyolefin resins, polyethylene is the most inexpensive because of its low cost, low coefficient of friction, excellent processability after molding, excellent chemical resistance, and low moisture absorption and water absorption of the material itself. preferable.

The density of polyethylene is preferably 890 to 970 kg / m ³ , more preferably 900 to 960 kg / m ³ , and even more preferably 910 to 950 kg / m ³ . When the density is 890 kg / m ³ or more, the rigidity of the cylindrical body tends to be further improved. Further, when the density is 970 kg / m ³ or less, the handleability tends to be further improved. Here, the density of polyethylene can be obtained by measuring according to JIS K 7112: 1999 by the density gradient tube method (23 ° C.).

The viscosity average molecular weight of polyethylene is preferably 100,000 to 10 million, more preferably 1 million to 10 million, and even more preferably 2 million to 10 million. When the viscosity average molecular weight of polyethylene is within the above range, wear resistance tends to be further improved, and sufficient strength to withstand high pumping pressure tends to be obtained. A polyethylene having a viscosity average molecular weight of 1 million or more is referred to as "ultra high molecular weight polyethylene" in this embodiment.

The viscosity average molecular weight can be determined, for example, by the method shown below. First, polyethylene is dissolved in decalin (decahydronaphthalen) to prepare multiple solutions with different concentrations. The reduced viscosities (ηsp / C) of these solutions are determined using a Ubbelohde type viscometer in a constant temperature bath at 135 ° C. A linear equation of the concentration (C) and the reduced viscosity (ηsp / C) of the polymer is derived, and the ultimate viscosity ([η]) extrapolated to the concentration 0 is obtained. From this ultimate viscosity ([η]), the viscosity average molecular weight (Mv) can be obtained according to the following formula.
Mv = 5.34 × 10 ⁴ × [η] ^1.49

Among the above, as the resin constituting the cylindrical body, ultra-high molecular weight polyethylene is most preferable in terms of pressure resistance, low friction, high water repellency (contact angle), abrasion resistance, transparency and the like.

The concrete pumping pipe may be a mixed raw material of polyethylene having different density and / or viscosity average molecular weights as the raw material resin, or may be a mixed raw material of polyethylene and a raw material resin other than polyethylene.

Further, in the concrete pumping pipe of the present embodiment, various additives such as a heat stabilizer, an ultraviolet absorber, a coloring pigment, and a flame retardant may be added to the resin as long as the effects of the present embodiment are not impaired.

(UV absorber)
The cylindrical body of the present embodiment may further contain an ultraviolet absorber as an additive, if necessary. The ultraviolet absorber is not particularly limited as long as it is a substance that absorbs ultraviolet rays in a wavelength range harmful to the resin. For example, a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, a cyanoacrylate-based ultraviolet absorber, and the like are included.

The benzophenone-based ultraviolet absorber is not particularly limited, and examples thereof include 2-hydroxy-4-octoxybenzophenone. The benzotriazole-based ultraviolet absorber is not particularly limited, and examples thereof include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole. The cyanoacrylate-based ultraviolet absorber is not particularly limited, and examples thereof include 2-ethylhexyl-2-cyano-3 and 3'-diphenyl acrylate. Of these, benzophenone-based ultraviolet absorbers are more preferable. By using such an ultraviolet absorber, the weather resistance tends to be further improved. In addition, in this embodiment, the weather resistance means the resistance to the deterioration of physical properties when the above-mentioned accelerated exposure test is performed.

The content of the ultraviolet absorber is preferably 0.01 to 10% by mass, more preferably 0.01 to 10% by mass, and further preferably 0.01 to 10% by mass with respect to the total amount of the cylinder. %. When the content of the ultraviolet absorber is within the above range, the weather resistance tends to be further improved.

(Dynamic friction coefficient)
The coefficient of kinetic friction of the inner surface of the cylindrical body made of resin is 0.07 to 0.30, preferably 0.07 to 0.20, and more preferably 0.07 to 0.15. When the coefficient of kinetic friction on the inner surface is within the above range, it is not necessary to use a postponing material, blockage is less likely to occur, and fluctuations in the discharged concrete component can be further suppressed.

(Amount of wear)
The amount of wear by the sand slurry wear method on the inner surface of the cylindrical body, which will be described later, is preferably 10 mg or less, more preferably 8 mg or less, still more preferably 5 mg or less, and most preferably 2 mg or less. When the amount of wear on the inner surface of the cylindrical body is 10 mg or less, the wear resistance tends to be further improved. The lower limit of the amount of wear on the inner surface of the cylindrical body is not particularly limited, but is 0 mg or more.

(Tensile breaking strength)
The tensile breaking strength of the cylinder after the accelerated exposure test for 1200 hours at a black panel temperature of 63 ° C. ± 3 ° C. is preferably 50% or more with respect to the tensile breaking strength of 100% before the accelerated exposure test. It is more preferably 75 to 150%, still more preferably 80 to 120%. Since the tensile breaking strength of the cylindrical body after the accelerated exposure test is 50% or more, the weather resistance of the concrete delivery pipe exposed to high temperature in direct sunlight tends to be better.

(Tension breaking elongation)
From the same viewpoint, the tensile elongation at break after the accelerated exposure test is preferably 50% or more, preferably 50% or more, with respect to the tensile elongation at break of 100% before the accelerated exposure test. It is 50% or more, more preferably 75 to 150%, and even more preferably 80 to 120%. Since the tensile elongation at break of the cylindrical body after the accelerated exposure test is 50% or more, the weather resistance of the concrete delivery pipe exposed to high temperature in direct sunlight tends to be better.

[Outer shape]
In the cylindrical body of the present embodiment, at least the innermost layer and the outermost layer are made of resin. The cylindrical body is composed of a resin tube, a multi-layer tube composed of a multi-layer resin layer, a multi-layer tube in which an arbitrary inner layer is provided on a tube composed of a single-layer resin layer, and a single-layer resin layer. A single-layer tube can be mentioned. Of these, a single-layer tube is preferable.

The configuration other than the portion made of the resin of the innermost layer and the outermost layer of the cylindrical body constituting the concrete pumping pipe made of the multilayer pipe of the present embodiment is not particularly limited, but for example, reinforcement made of a high-strength resin such as aramid. Examples thereof include a heat insulating layer such as tape and polyurethane foam, a steel pipe, a steel strip, an iron wire, and a fiber structure (fabric, etc.). From the viewpoint of weight and visibility of the contents inside the cylinder, it is preferable that it does not contain metal, and even if it is a resin, it is preferable that it has light transmission.

The outer diameter, inner diameter, and thickness of the cylindrical body are not particularly limited as long as they are the sizes used for conventional concrete pumping pipes. For example, the maximum outer diameter R is preferably 100 to 250 mm, more preferably 110 to 240 mm, and even more preferably 120 to 230 mm. The inner diameter r of the cylindrical body is preferably 70 to 170 mm, more preferably 80 to 160 mm, and even more preferably 90 to 150 mm. By using such a cylindrical body, concrete containing solids of various sizes can be efficiently pumped in a relatively large amount, and the pumping performance tends to be further improved.

Further, the thickness (Rr) / 2 of the cylindrical body is preferably 5 to 20 mm, more preferably 7.5 to 17.5 mm, still more preferably 10 to 15 mm. By using such a cylinder, the life of the concrete pumper tends to be longer.

Further, the length of the cylindrical body is not particularly limited as long as it is the size used for the conventional concrete pumping pipe. For example, the total length Lw of the cylindrical body is preferably 0.3 to 4 m, more preferably 0.5 to 3.7 m, and further preferably 0.7 to 3.5 m.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

<Water pressure resistance test>
The water pressure resistance of the concrete pumping pipe of the example and the steel pipe of the comparative example was confirmed according to the high pressure test of the steel pipe. Specifically, both ends of the pressure feed pipe having a length of 1000 mm were fastened with a sealing plug having a built-in pressure pipe and fixed to a sealing jig. Tap water at room temperature was poured from the pressure pipe into the pressure feed pipe, pressurized to 25 MPa, and the state of leakage and rupture after 2 minutes was confirmed visually and by pressure measurement.

<Dynamic friction coefficient>
Each of the concrete pumping pipe of the example and the steel pipe of the comparative example was cut to prepare a test piece having an outer diameter of 25.6 × an inner diameter of 20 mm × a length of 15 mm. The coefficient of dynamic friction of the obtained test piece was confirmed in accordance with JIS7218. Specifically, it was measured by friction with steel (S45C) under the conditions of a surface pressure of 0.83 kg / cm ^{2 and a linear velocity of 6.2 cm / sec by the thrust wear method.}

<Evaluation method of contact angle>
Each of the concrete pumping pipe of the example and the steel pipe of the comparative example was cut to prepare a flat plate having a size of 50 × 50 mm. The contact angle with water was measured by the static sessile drop method. Specifically, the contact angle when 20 μl of water was dropped on the flat plate was observed with a microscope, and the contact angle was measured.

<Evaluation method of wear amount>
The concrete pumping pipes and steel pipes of Examples and Comparative Examples were cut to prepare rectangular parallelepiped test pieces having a thickness of 4 mm and a thickness of 65 mm × 30 mm. Then, the amount of wear was measured by the sand slurry wear method. More specifically, a test piece prepared by mixing the abrasive to be used (White Morandum # 20 manufactured by Showa Denko) and water at a ratio of 1: 1 is placed in a container and fixed vertically to the shaft. The two sheets were rotated like sales expansion blades so as to be buried 10 mm or more from the sand slurry surface. The rotation speed was 250 rpm. The weight of each test piece after 60,000 rotations and 180,000 rotations was measured, and the value obtained by subtracting the weight after 180,000 rotations from the weight of the test piece after 60,000 rotations was taken as the amount of wear. The average value measured for the three test pieces was taken as the amount of wear of the material.
For reference, the amount of wear of general materials is shown below.
Cast nylon: 5.6 mg
High density polyethylene: 7.7 mg
Nylon 66: 8.3 mg
Polyurethane: 8.4 mg
Fluororesin: 9.0 mg
SUS: 9.8 mg
Polypropylene: 20.4 mg
Polyacetal: 24.0 mg
Bakelite: 27.8 mg
Brass: 45.0 mg
Low density polyethylene: 48.2 mg

<Evaluation method of transmittance>
The concrete pumping pipes of Examples and Comparative Examples were cut to prepare test pieces having a thickness of 2 mm. Then, the transmittance of the test piece was evaluated according to JIS-K-7361 (total light transmittance measurement standard) and JIS-K-7136 (haze measurement standard). Specifically, using HAZEMATER HM-150 manufactured by Murakami Color Technology Research Institute, the total light transmittance (%) of both the external haze and the internal haze (preventing unevenness with pure water in addition to the quartz cell) was measured.

<Method of accelerated exposure test>
The concrete pumping pipes of Examples and Comparative Examples were cut to prepare test pieces. The obtained test piece was subjected to a sunshine carbon arc type acceleration test, and the tensile strength at break and the elongation at break before and after the test were measured. Specifically, using a sunshine weather meter manufactured by Suga Test Instruments (sometimes called a weather meter), according to JIS-B-7753, the black panel temperature is 63 ° C (± 3 ° C) and the humidity is 50% (± 5%). ), With rainfall (120 minutes cycle; 102 minutes dry + 18 minutes rainfall), a 1200 hour exposure test was conducted.

Using the test pieces before and after the above test, tensile strength at break and tensile strength in accordance with JIS K 7127: 1999 (test method for tensile properties of plastics) and JIS Z 2241: 2011 (test method for tensile properties of metal materials). The elongation at break was measured.

<Initial pumping test method>
Three concrete pumping pipes of Examples or Comparative Examples were connected to the concrete pump truck with joints, and a concrete pumping test was conducted under the conditions shown in Table 1. As the pumped concrete, ordinary concrete was used. When a postponement material was used, mortar was used as the postponement material. Prior to the concrete pumping, 1000 kg of the forwarding material was introduced into the concrete pumping pipe, and the forwarding material was discharged from the other end of the concrete pumping pipe to adhere to the inner surface of the concrete pumping pipe.
Concrete was supplied to pumping pipe from the pump wheel was observed initial pressure 1.5 MPa, pumping state when the 2m ³ pumped at a rate 10 m ³ / h.

<Pushing state>
Under the conditions shown in Table 1, it was confirmed whether the inside of the pumping pipe was blocked by the time of pumping ^{2 m 3, and the pumped state was evaluated.} If no blockage occurred, it was rated as "good", and if pumping could not be completed due to blockage, it was rated as "blockage:".

<Visual confirmation of concrete passing position>
In the pumping test, the position of the concrete inside was visually confirmed from the outside of the concrete pumping pipe under fine weather, and the visibility was evaluated.

<Evaluation test for estimated amount of casting>
Following the initial pumping test, concrete ^{was pumped to a total of 5000 m 3} under the same conditions, and the following evaluations were carried out. When blockage was about to occur due to long-term pressure feeding, the pressure was once raised to 25 MPa, and when the blockage was resolved, the original conditions were restored and pressure feeding was continued. If the obstruction was not resolved, the test was terminated at that point.

<Liquid leak>
Under the conditions shown in Table 1, it was confirmed whether or not the concrete leaked from the joint which is the connection part of the concrete pumping pipe by the time of pumping ^{5000 m 3, and it was evaluated whether or not the liquid leaked.}

<Characteristics of discharged concrete>
Under the conditions shown in Table 1, it was confirmed whether or not the composition of the discharged concrete fluctuated by the time of pumping ^{5000 m 3, and the properties of the discharged concrete were evaluated.}

<Explosion prediction / body swelling>
Under the conditions shown in Table 1, it was confirmed whether or not the body of the concrete pumping pipe had bulged by the time of pumping ^{5000 m 3.} When the occurrence of swelling could be visually observed, the pumping amount until the site burst was measured by continuing pumping and defined as "the amount that can be pumped after the body swells".

[Pressure pipe A]
A cylindrical body was molded by molding using an ultra-high molecular weight polyethylene powder (Sunfine UH910, manufactured by Asahi Kasei Corporation). As shown in FIG. 1, the end of the cylindrical body was provided with a spiral male screw groove (A type). The pitch of the male screw groove was 8 mm. The obtained cylindrical body was used as a concrete pumping pipe A. The wear ratio of this pumping pipe was 1.

[Pressure pipe B]
A cylindrical body was molded by molding using an ultra-high molecular weight polyethylene powder (Sunfine UH910, manufactured by Asahi Kasei Corporation). At this time, an ultraviolet absorber, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, was added at 3000 ppm (0.3% by mass) with respect to polyethylene. As shown in FIG. 1, the end of the cylindrical body was provided with a spiral male screw groove (A type). The pitch of the male screw groove was 5 mm. The obtained cylindrical body was used as a concrete pumping pipe B.

[Pressure pipe C]
A cylindrical body was molded by molding using an ultra-high molecular weight polyethylene powder (Sunfine UH910, manufactured by Asahi Kasei Corporation). At this time, an ultraviolet absorber, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, was added at 3000 ppm (0.3% by mass) with respect to polyethylene. The end of the cylinder was provided with a circumferential groove (B type) as shown in FIG. The obtained cylindrical body was used as a concrete pumping pipe C.

[Pressure pipe D]
A commercially available steel pipe (manufactured by Linex Co., Ltd., product name Green Line) was used as the concrete pumping pipe D of the comparative example.

合格 ：破裂や漏れが発生せず
ＡＳ ：超高分子量ポリエチレン
Ａタイプ：図1のとおり端部に螺旋状の雄螺子溝を有するタイプ
Ｂタイプ：図2のとおり端部に円周溝

Passed: No rupture or leakage AS: Ultra-high molecular weight polyethylene A type: Type B type with a spiral male screw groove at the end as shown in Fig. 1: Circumferential groove at the end as shown in Fig. 2.

※廃材数量：コンクリートの圧送に先立ち使用した先送り材の廃材量である。

* Amount of waste material: The amount of waste material of the postponed material used prior to the pumping of concrete.

The concrete pumping pipe of the present invention has industrial applicability in the field of concrete pumping.

Claims (10)

A concrete pumping pipe that does not have metal pipes in at least the innermost and outermost layers.
At least the innermost layer and the outermost layer have spiral male screw grooves or circumferential grooves on the outer peripheral surfaces of both ends of a cylinder made of resin.
Concrete pumping pipe. The maximum outer diameter R of the cylindrical body is 100 to 250 mm, and the cylinder has a maximum outer diameter R of 100 to 250 mm.
The inner diameter r of the cylindrical body is 70 to 210 mm, and the inner diameter r is 70 to 210 mm.
The thickness (Rr) / 2 of the cylinder is 5 to 20 mm.
The concrete pumping pipe according to claim 1. The total length Lw of the cylindrical body is 0.3 to 4 m.
The concrete pumping pipe according to claim 1 or 2. The pitch of the male screw groove is 3 to 10 mm.
The concrete pumping pipe according to any one of claims 1 to 3. 'And _2, the ratio R of the inner diameter r' maximum outer diameter R of the flange to be formed between the end face and the circumferential groove of the cylindrical body ₂ / r is a 1.1 to 1.4,
The concrete pumping pipe according to any one of claims 1 to 3. The coefficient of kinetic friction on the inner surface of the cylinder is 0.07 to 0.15.
The concrete pumping pipe according to any one of claims 1 to 5. The amount of wear of the cylindrical body by the sand slurry wear method is 10 mg or less.
The concrete pumping pipe according to any one of claims 1 to 6. The resin contains ultra high molecular weight polyethylene.
The concrete pumping pipe according to any one of claims 1 to 7. The viscosity average molecular weight of the ultra-high molecular weight polyethylene contained in the resin is 10 × 10 ⁴ or more and 1000 × 10 ⁴ or less.
The concrete pumping pipe according to any one of claims 1 to 8. The cylinder further contains an ultraviolet absorber and
The content of the ultraviolet absorber is 0.01 to 10% by mass with respect to the total amount of the cylinder.
The concrete pumping pipe according to any one of claims 1 to 9.

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