Concrete pressure pipe

Abstract

Provided is a concrete pumping pipe that does not comprise a metal pipe, wherein: the concrete pumping pipe includes a cylindrical body made of resin; the coefficient of kinetic friction on the inner surface of the cylindrical body is 0.07-0.30; the cylindrical body does not rupture or leak in a hydraulic-pressure resistance test of 25MPa; and the total light transmittance in a 2mm thick test piece of the cylindrical body is at least 10%.

Description

[Technical Field]

[0001] The present invention relates to a concrete pumping pipe. [Background technology]

[0002] Fresh concrete (hereafter simply referred to as "concrete") before hardening is a mixture of cement, water, fine aggregate, coarse aggregate, and optional admixtures, and possesses both liquid and solid properties. When pumped, fresh concrete forms a solid plug inside the steel pipe, generating friction with the pipe's inner wall. During pumping, the coarse aggregate is primarily located at the center of the steel pipe, while the water and cement paste are primarily located on the inner wall of the steel pipe. The water and other materials on the inner wall buffer the frictional resistance that occurs during pumping, allowing the concrete to be pumped. The pumpability of concrete varies depending on its type. For example, concrete with a low water content or other high viscosity has high frictional resistance, leading to blockage of the steel pipe. Concrete with a high water content, for example, is prone to solid-liquid separation, leading to blockage of the steel pipe and a deterioration in the quality of the pumped concrete.

[0003] Generally, steel pipes are used to pump fresh concrete (see, for example, Patent Document 1). Steel pipes are connected with joints as needed to pump fresh concrete to the desired pouring location. Straight steel pipes are approximately 1, 2, or 3 meters long, and the higher the pressure resistance of the steel pipe, the thicker the pipe wall and the heavier it becomes. For example, a 3-meter high-pressure steel pipe weighs approximately 65 kg. This means that multiple people need to handle one steel pipe at a construction site. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-085741 Summary of the Invention [Problem to be solved by the invention]

[0005] If it were possible to replace such steel pipes with resin pipes other than metal pipes, it would be easier to prepare concrete pumping pipes at construction sites, and overall work efficiency could be expected to improve. However, it has been thought that it is difficult to realize a concrete pumping pipe without metal pipes that has the pressure resistance required to pump heavy fresh concrete and can withstand the wear that occurs when pumping fresh concrete.

[0006] Furthermore, with the conventional pumping method using steel pipes, it was necessary to confirm up to what position the fresh concrete had been pumped by tapping on the steel pipe and listening to the change in sound, and the longer the pumping distance, the more time and effort this confirmation process required. If it were possible to check the status of the concrete pumping pipe more easily, it would be possible to deal with blockages and other problems at an early stage, and concrete pouring work could be carried out more safely.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a concrete pressure pipe that does not have a metal pipe, has excellent pressure-transport performance, is lightweight, and is highly safe. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems, and as a result have found that a concrete pressure pipe using a cylindrical body made of ultra-high molecular weight polyethylene having predetermined properties can solve the above problems, which has led to the completion of the present invention.

[0009] That is, the present invention is as follows. [1] A concrete pumping pipe that does not include a metal pipe, It has a cylindrical body made of resin, The coefficient of dynamic friction of the inner surface of the cylindrical body is 0.07 to 0.30, The cylinder did not burst or leak during a 25 MPa water pressure test, The total light transmittance per 2 mm thick test piece of the cylindrical body is 10% or more. Concrete pressure pipe. [2] The contact angle of the inner surface of the cylindrical body is 55° or more. A concrete pressure pipe according to [1]. [3] The amount of wear on the inner surface of the cylindrical body by a sand slurry wear method is 10 mg or less; A concrete pressure pipe according to [1] or [2]. [4] the tensile breaking strength of the cylindrical body after an accelerated exposure test at a black panel temperature of 63°C ± 3°C for 1200 hours is 50% or more of the tensile breaking strength (100%) before the accelerated exposure test; The tensile breaking elongation of the cylindrical body after the accelerated exposure test is 50% or more relative to 100% of the tensile breaking elongation before the accelerated exposure test. [1] - [3] The concrete pressure pipe according to any one of the above. [5] A cylindrical body made of resin has a spiral male screw groove or a circumferential groove on the outer peripheral surface at both ends thereof. [1] - [4] The concrete pressure pipe according to any one of the above. [6] The cylindrical body is a single-layer tube. [1] - [5] The concrete pressure pipe according to any one of the above. [7] The maximum outer diameter R of the cylindrical body is 100 to 250 mm, The inner diameter r of the cylindrical body is 70 to 170 mm, The thickness (Rr) / 2 of the cylindrical body is 5 to 20 mm. [1] - [6] The concrete pressure pipe according to any one of the above. [8] The total length Lw of the cylindrical body is 0.3 to 4 m. [1] - [7] The concrete pressure pipe according to any one of the above. [9] The pitch of the male screw groove is 3 to 10 mm. [5] A concrete pressure pipe according to [5].

[10] The ratio R'2 / r of the maximum outer diameter R'2 of the flange formed between the end face of the cylindrical body and the circumferential groove to the inner diameter r is 1.05 to 1.4. [1] - [9] The concrete pressure pipe according to any one of the above.

[11] The resin includes ultra-high molecular weight polyethylene. [1] The concrete pressure pipe according to any one of [1] to

[10] .

[12] The viscosity average molecular weight of the ultra-high molecular weight polyethylene contained in the resin is 10 × 10 4 Over 1000 x 10 4 Below is the

[11] A concrete pressure pipe according to

[11] .

[13] the cylinder further comprises an ultraviolet absorber; The content of the ultraviolet absorber is 0.01 to 10% by mass relative to the total amount of the cylindrical body. [1] -

[12] The concrete pressure pipe according to any one of the above.

[14] A molding step of manufacturing the concrete pressure pipe according to any one of [1] to

[13] by screw extrusion molding a resin into a hollow cylindrical shape, A method for manufacturing concrete pressure pipes. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a concrete pressure pipe that does not have a metal pipe, has excellent pressure-transporting performance, is lightweight, and is safe and easy to handle. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of the concrete pumping pipe of this embodiment cut along the center line of the cylinder. FIG. [Figure 2] FIG. 10 is a diagram showing an image in which the concrete inside the concrete pumping pipe of this embodiment can be seen when in use. [Figure 3] FIG. 2 is a cross-sectional view showing the state in which the concrete pressure pipe of the present embodiment is connected. [Figure 4] FIG. 10 is another cross-sectional view showing the state in which the concrete pressure pipe of the present embodiment is connected. DETAILED DESCRIPTION OF THE INVENTION

[0012] Below, we will explain in detail the embodiment of the present invention (hereinafter referred to as the ``present embodiment''), but the present invention is not limited to this and various modifications are possible within the scope of the gist of the present invention.

[0013] [Concrete pressure pipe] The concrete pressure pipe of this embodiment is a concrete pressure pipe that does not have a metal pipe, and has a cylindrical body made of resin, the dynamic friction coefficient of the inner surface of the cylindrical body is 0.07 to 0.15, the cylindrical body does not burst or leak in a 25 MPa water pressure resistance test, and the total light transmittance per 2 mm thick test piece of the cylindrical body is 10% or more.

[0014] Traditionally, metal pipes such as steel pipes have been used to pump concrete. This is presumably because the concrete being pumped is heavy and requires a certain amount of pressure to pump, and metal pipes are thought to be more suitable for safe pumping.

[0015] However, it has become clear that metal pipes are not suitable for pumping concrete. For example, each metal pipe is heavy, and multiple workers must handle it carefully to avoid accidents. This poses challenges in terms of work safety and on-site labor hours.

[0016] Furthermore, because the coefficient of dynamic friction between metal pipes and concrete is relatively high, concrete is usually pumped into the metal pipes using advance materials, but this generates a large amount of waste material, making it impossible to reduce the labor required to use advance materials and the large disposal costs of advance materials. Furthermore, due to the high coefficient of dynamic friction, the components of the concrete tend to separate during pumping, causing the concrete composition discharged from the pumping pipe outlet to fluctuate. Such fluctuations have a significant impact on the strength of the building, and the concrete with the fluctuated composition must be discarded, further increasing disposal costs.

[0017] Furthermore, because it is impossible to see inside a metal pipe, it is not possible to immediately check how far the concrete has reached in the concrete pumping pipe, and it is not possible to notice that the concrete has clogged the concrete pumping pipe midway. If such a blockage occurs, not only can the concrete pumping pipe burst, causing an accident, but the concrete pumping pipe, which took a lot of man-hours to install, must be discarded and relocated, which can significantly delay work. Furthermore, if a blockage occurs, the metal pipe may burst suddenly in an unexpected location, increasing the danger of the work.

[0018] In contrast, the concrete pumping pipe of this embodiment uses a resin cylinder with predetermined properties as a concrete pumping pipe that does not include a conventional metal pipe such as a steel pipe. By not including a metal pipe such as a steel pipe, it is possible to realize a concrete pumping pipe that is lighter and can be handled more safely at the work site, unlike conventional concrete pumping pipes that are heavy and difficult to handle.

[0019] Furthermore, since the concrete pumping pipe of this embodiment has a desired coefficient of dynamic friction, it is not necessary to use a pre-transporting material. Therefore, the process of using a pre-transporting material itself can be eliminated, and the costs of using and disposing of the pre-transporting material can be significantly reduced. Furthermore, separation of concrete components during pumping can be suppressed, and the costs of disposing of concrete with a fluctuating composition can be significantly reduced.

[0020] Furthermore, in this embodiment, by using a cylindrical body made of resin, it is possible to ensure visibility of the contents inside the cylindrical body. As a result, even if concrete gets clogged in the concrete pumping pipe, it is possible to quickly confirm the blockage and prevent burst accidents. Furthermore, when the internal pressure of the resin cylindrical body increases, it expands outward to an extent that is immediately visible before it breaks. This allows on-site workers to immediately recognize the location of a potential burst and take appropriate refuge. The concrete pumping pipe of this embodiment will be described in detail below.

[0021] Figure 1 shows a cross-sectional view of the concrete pumping pipe of this embodiment, cut along the centerline of the cylinder. The concrete pumping pipe 10 has a cylindrical body 1 made of resin, and may have flanges 2 at both ends for joining. By using a cylindrical body made of resin, the concrete pumping pipe 10 of this embodiment can ensure visibility of the contents (concrete 3) inside the cylindrical body during use (Figure 2).

[0022] (dynamic friction coefficient) The dynamic friction coefficient of the inner surface of the resin cylinder is 0.07 to 0.30, preferably 0.07 to 0.20, and more preferably 0.07 to 0.15. When the dynamic friction coefficient of the inner surface is within the above range, the use of a pre-filling agent is unnecessary, clogging is less likely to occur, and fluctuations in the discharged concrete components can be further suppressed. In particular, in order to achieve a dynamic friction coefficient of 0.15 or less, which is significantly lower than conventional values, on the inner surface of a cylinder made of ultra-high molecular weight polyethylene (UHMWPE), as described below, it is preferable to perform molding by screw extrusion, as described below.

[0023] (Water pressure resistance test) Furthermore, the resin cylinder does not burst or leak in a 25 MPa water pressure resistance test. Since the water pressure resistance performance is within the above range, there is no need to use metal pipes, even when pumping heavy concrete at high pressure. In this embodiment, "no burst or leak in a 25 MPa water pressure resistance test" means that neither burst nor leak occurs. The "25 MPa water pressure resistance test" refers to a test in which room temperature tap water is poured into the cylinder from a pressurized pipe, pressurized to 25 MPa, and the occurrence of leaks or bursts is confirmed after two minutes. Specific conditions are described in the examples.

[0024] (Total light transmittance) The total light transmittance per 2 mm thick test piece of the cylinder is 10% or more, preferably 20 to 90%, more preferably 30 to 80%, and even more preferably 40 to 70%. When the total light transmittance per 2 mm thick test piece of the cylinder is 10% or more, the visibility of the contents tends to be further improved. When the total light transmittance per 2 mm thick test piece of the cylinder is 90% or less, the mechanical strength of the cylinder tends to be further improved.

[0025] (contact angle) The contact angle of the inner surface of the cylinder is preferably 55° or more, more preferably 60° to 90°, and even more preferably 65° to 85°. A contact angle of 55° or more on the inner surface of the cylinder makes it easier to repel the water components contained in the concrete. In metal pipes, water components tend to adhere to the inner surface of the metal pipe, which can easily cause differences in the pumping speed between the center and the outside of the pipe, resulting in fluctuations in the composition of the discharged concrete. However, the cylinder of this embodiment can suppress such fluctuations, making the use of advance materials unnecessary, and is less likely to cause blockages, which tends to further suppress fluctuations in the components of the discharged concrete.

[0026] (wear amount) The amount of wear on the inner surface of the cylindrical body by a sand slurry abrasion method, which will be described later, is preferably 10 mg or less, more preferably 8.0 mg or less, even more preferably 5.0 mg or less, and most preferably 2.0 mg or less. When the amount of wear on the inner surface of the cylindrical body is 10 mg or less, the abrasion resistance tends to be further improved. There is no particular lower limit for the amount of wear on the inner surface of the cylindrical body, but it is 0 mg or more.

[0027] (Tensile breaking strength) The tensile breaking strength of the cylinder after 1200 hours of accelerated exposure testing at a black panel temperature of 63°C ± 3°C is preferably 50% or more, more preferably 75 to 150%, and even more preferably 80 to 120%, of the tensile breaking strength before the accelerated exposure testing (100%). When the tensile breaking strength of the cylinder after the accelerated exposure testing is 50% or more, the weather resistance of the concrete pressure pipe exposed to high temperatures under direct sunlight tends to be better.

[0028] (Tensile elongation at break) From the same viewpoint, the tensile breaking elongation of the cylindrical body after the accelerated exposure test is preferably 50% or more, more preferably 50% or more, more preferably 75 to 150%, and even more preferably 80 to 120%, of the tensile breaking elongation of 100% before the accelerated exposure test. When the tensile breaking elongation of the cylindrical body after the accelerated exposure test is 50% or more, the weather resistance of the concrete pressure pipe exposed to high temperatures under direct sunlight tends to be better.

[0029] (Resin composition) Examples of resins that can be used to form the concrete pumping pipe include thermoplastic resins and thermosetting resins. The resins may also contain additives such as ultraviolet absorbers.

[0030] The thermoplastic resin is not particularly limited, but examples thereof include polyolefin resins, polyester resins, polyarylate, liquid crystal polyester, polyvinyl chloride, polyvinyl alcohol, ethylene vinyl acetate, polystyrene, acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, polymethyl methacrylate, polyamide resins, polyacetal, polycarbonate, fluorine-based resins, polyether ether ketone, polyether sulfone, and polyphenylene sulfide.

[0031] The thermosetting resin is not particularly limited, but examples thereof include phenol resin, urea resin, melamine resin, allyl resin, and epoxy resin.

[0032] Among these, thermoplastic resins are preferred from the viewpoints of shaping properties, secondary processability, etc. Furthermore, among thermoplastic resins, polyolefin resins, typified by polyethylene and polypropylene, are preferred from the viewpoints of low cost, excellent chemical resistance, excellent processability, low hygroscopicity and water absorption properties of the material, etc.

[0033] The polyolefin resin is not particularly limited, but examples thereof include ethylene homopolymers; copolymers of ethylene and one or more α-olefins such as propylene, butene-1, hexene-1, and octene-1; copolymers of ethylene and vinyl acetate, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, and the like; propylene homopolymers; and copolymers of propylene and one or more α-olefins such as ethylene and butene-1.

[0034] Among polyolefin resins, polyethylene is most preferred because it is inexpensive, has a small coefficient of friction, is excellent in processability after molding, has excellent chemical resistance, and has low moisture absorption and water absorption properties of the material itself.

[0035] The density of the polyethylene is preferably 890 to 970 kg / m 3 and more preferably 900 to 960 kg / m3 and more preferably 910 to 950 kg / m 3 The density is 890 kg / m 3 By setting the density to 970 kg / m or more, the rigidity of the cylindrical body tends to be improved. 3 The handleability tends to be improved by satisfying the following: Here, the density of the polyethylene can be obtained by measurement by the density gradient tube method (23°C) in accordance with JIS K 7112:1999.

[0036] The viscosity average molecular weight of the polyethylene is preferably 10×10 4 ~1000×10 4 and more preferably 100×10 4 ~1000×10 4 and more preferably 300×10 4 ~1000×10 4 When the viscosity average molecular weight of the polyethylene is within the above range, the abrasion resistance is further improved and sufficient strength to withstand high pumping pressure tends to be obtained. In this embodiment, polyethylene having the above viscosity average molecular weight is referred to as "ultra-high molecular weight polyethylene."

[0037] The viscosity average molecular weight can be determined, for example, by the following method. First, polyethylene is dissolved in decalin (decahydronaphthalene) to create multiple solutions of different concentrations. The reduced viscosity (ηsp / C) of each solution is determined using an Ubbelohde-type viscometer in a thermostatic bath at 135°C. A linear equation is derived for the concentration (C) and the reduced viscosity (ηsp / C) of the polymer, and the intrinsic viscosity ([η]) is calculated by extrapolating it to a concentration of 0. The viscosity average molecular weight (Mv) can be calculated from this intrinsic viscosity ([η]) according to the following equation. Mv=5.34×10 4 ×[η] 1.49

[0038] The raw material resin of the concrete pressure pipe may be a mixture of polyethylenes having different densities and / or viscosity average molecular weights, or may be a mixture of polyethylene and a raw material resin other than polyethylene.

[0039] Furthermore, in the concrete pressure pipe of this embodiment, various additives such as heat stabilizers, ultraviolet absorbers, coloring pigments, and flame retardants may be added to the resin, as long as the effects of this embodiment are not impaired.

[0040] (ultraviolet absorber) The cylindrical body of this embodiment may further contain an ultraviolet absorber as an additive, if necessary. The ultraviolet absorber is not particularly limited as long as it absorbs ultraviolet light in a wavelength range that is harmful to resin. Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers.

[0041] Benzophenone-based UV absorbers are not particularly limited, but examples thereof include 2-hydroxy-4-octoxybenzophenone. Benzotriazole-based UV absorbers are not particularly limited, but examples thereof include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. Cyanoacrylate-based UV absorbers are not particularly limited, but examples thereof include 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate. Among these, benzophenone-based UV absorbers are more preferred. Use of such UV absorbers tends to further improve weather resistance. In the present embodiment, weather resistance refers to resistance to deterioration of physical properties when the above-mentioned accelerated exposure test is performed.

[0042] The content of the ultraviolet absorber is preferably 0.01 to 10 mass %, more preferably 0.01 to 10 mass %, and even more preferably 0.01 to 10 mass %, relative to the total mass of the cylindrical body. When the content of the ultraviolet absorber is within the above range, weather resistance tends to be further improved.

[0043] [External shape] The cylindrical body of this embodiment is a resin pipe without a metal pipe. The cylindrical body may be a multi-layer pipe made of multiple resin layers, a multi-layer pipe made of a single resin layer with an optional inner layer, or a single-layer pipe made of a single resin layer. Among these, a single-layer pipe is preferable. It is possible to wrap a metal band around part of the outer periphery of the resin cylinder to prevent bursting or to provide a handle for transportation. Even such a configuration falls under the category of a resin concrete pressure pipe without a metal pipe according to the present invention.

[0044] The outer diameter, inner diameter, and thickness of the cylinder are not particularly limited as long as they are the same sizes as those used in 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 cylinder is preferably 70 to 170 mm, more preferably 80 to 160 mm, and even more preferably 90 to 150 mm. By using such a cylinder, it is possible to efficiently pump a relatively large amount of concrete containing solids of various sizes, and pumping performance tends to be further improved.

[0045] Furthermore, the thickness (Rr) / 2 of the cylinder is preferably 5 to 20 mm, more preferably 7.5 to 17.5 mm, and even more preferably 10 to 15 mm. By using such a cylinder, the life of the concrete pumping pipe tends to be longer.

[0046] The length of the cylinder is not particularly limited as long as it is a size that is used in conventional concrete pumping pipes. For example, the total length Lw of the cylinder is preferably 0.3 to 4 m, more preferably 1.5 to 3.7 m, and even more preferably 2.0 to 3.5 m.

[0047] FIG. 3 shows a cross-sectional view of a concrete pumping pipe according to this embodiment in a connected state. The concrete pumping pipe 10 has a cylindrical body 1 made of resin, with spiral male thread grooves 40 at both ends for connection with joints 30 via couplings 20. The couplings 20 have circumferential grooves 50 into which the joints 30 fit and spiral female thread grooves 60 for threading with the spiral male thread grooves 40 at both ends of the cylindrical body 1. By providing such male thread grooves 40 and connecting the couplings 20, joints 30 used with conventional steel pipes can be reused. The couplings 20 and joints 30 may be made of resin or metal. In FIG. 3, R'1 indicates the maximum outer diameter of the male thread groove 40, which is designed to fit the female thread groove 60 of the coupling 20.

[0048] Here, the pitch of the male screw groove 40 is preferably 3 to 10 mm, more preferably 3 to 9 mm, and even more preferably 3 to 8 mm. When the pitch of the male screw groove 40 is within the above range, the strength (pressure resistance) of the threaded portion between the coupling 20 and the cylindrical body 1 is improved, and liquid leakage from the threaded portion tends to be further suppressed.

[0049] As another example, Fig. 4 shows a cross-sectional view of a concrete pumping pipe according to this embodiment in a connected state. The concrete pumping pipe 10 in Fig. 4 has a cylindrical body 1 made of resin, and has circumferential grooves 70 at both ends for connection with joints 30. More specifically, the circumferential grooves 70 form flanges 80, and the concrete pumping pipe 10 is connected to the joints 30 using these flanges 80. By providing such circumferential grooves 70, it is possible to reuse the joints 30 used in conventional steel pipes.

[0050] The ratio R'2 / r of the maximum outer diameter R'2 of the flange 80 formed between the end face of the cylindrical body 1 and the circumferential groove 70 to the inner diameter r is preferably 1.05 to 1.4. When the ratio R'2 / r is within the above range, the mechanical strength of both ends of the cylindrical body 1 is improved, and breakage of the ends tends to be less likely to occur.

[0051] The concrete pressure pipe 10 of this embodiment does not have a metal pipe, but instead uses a cylindrical body with at least the innermost and outermost layers made of resin, which makes it possible to ensure visibility of the contents (concrete) inside the cylindrical body during use.

[0052] The resin cylinder can be produced by a known method such as injection molding or extrusion molding, and can be hollowed out after molding into a solid cylinder, or can be molded into a hollow cylinder. However, the resin containing the ultraviolet absorber and having a viscosity average molecular weight of 10 × 10 4 ~1000×10 4 A hollow cylindrical body made of ultra-high molecular weight polyethylene is preferably extruded, and screw extrusion molding is particularly preferred. This method makes it possible to mold ultra-high molecular weight polyethylene resin, which is more difficult to mold into a cylindrical shape than general resins, into a long cylindrical body with a highly smooth inner circumferential surface. [Example]

[0053] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0054] <Water pressure resistance test> The water pressure resistance of the concrete pressure pipe of the example and the steel pipe of the comparative example was confirmed in accordance with the high-pressure test for steel pipes. Specifically, both ends of a 1000 mm long pressure pipe were fastened with sealing plugs with built-in pressure piping and fixed to a sealing jig. Room temperature tap water was poured into the pressure pipe from the pressure piping, and pressure was increased until the pressure from the device reached 25 MPa. After 5 minutes, the occurrence of leakage and bursting was confirmed by visual inspection and pressure measurement.

[0055] For the concrete pressure pipe of the example, the pressure in the device was further increased to 180 MPa, and after 2 minutes, the occurrence of leakage, swelling, and bursting was confirmed by visual inspection and pressure measurement.

[0056] <Dynamic friction coefficient> The concrete pumping pipe of the example and the steel pipe of the comparative example were each cut to prepare test pieces with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a length of 15 mm. The dynamic friction coefficients of the obtained test pieces were confirmed in accordance with JIS 7218. Specifically, the test pieces were subjected to a thrust wear method at a surface pressure of 0.83 kg / cm. 2 The measurement was carried out by rubbing against steel (S45C) at a linear velocity of 6.2 cm / sec.

[0057] <Contact angle evaluation method> The concrete pumping pipe of the example and the steel pipe of the comparative example were cut to create flat plates measuring 50 x 50 mm. The contact angle with water was measured using the static drop method. Specifically, the contact angle when 20 μl of water was dropped onto the flat plate was observed under a microscope and the contact angle was measured.

[0058] <Method for evaluating wear amount> The concrete pumping pipes and steel pipes of the examples and comparative examples were cut to prepare rectangular parallelepiped test pieces measuring 65 mm x 30 mm and 4 mm thick. The abrasion volume was then measured using a sand slurry abrasion method. More specifically, a sand slurry was prepared by mixing the abrasive (White Morundum #20 manufactured by Showa Denko) and water in a 1:1 ratio, and the container was filled with sand. Two test pieces were fixed vertically to a shaft and rotated like a vane, with the shaft buried at least 10 mm below the surface of the sand slurry. The rotation speed was 250 rpm. 6 x 10 4 After rotation, 18 × 10 4 After rotating the test piece, the weight of each test piece was measured and 6 × 10 4 From the weight of the test piece after rotation, 18 × 10 4 The weight after rotation was subtracted from the weight of the test piece, and the average value measured for the three test pieces was taken as the wear amount of the material. For reference, the wear amounts of common materials are shown below. Cast nylon: 5.6mg High density polyethylene: 7.7mg Nylon 66: 8.3mg Polyurethane: 8.4mg Fluorine resin: 9.0mg SUS: 9.8mg Polypropylene: 20.4mg Polyacetal: 24.0mg Bakelite: 27.8mg Brass: 45.0mg Low-density polyethylene: 48.2mg

[0059] <Method for evaluating total light transmittance> The concrete pumping pipes of the examples and comparative examples were cut to prepare test pieces with a thickness of 2 mm. The total light transmittance of the test pieces was then evaluated according to JIS-K-7361 (total light transmittance measurement standard) and JIS-K-7136 (haze measurement standard). Specifically, the total light transmittance (%) of both the external haze and the internal haze (preventing unevenness with pure water in addition to a quartz cell) was measured using a HAZEMATER HM-150 manufactured by Murakami Color Research Laboratory.

[0060] <Accelerated exposure test method> The concrete pumping pipes of the examples and comparative examples were cut to prepare test specimens. The resulting test specimens were subjected to a Sunshine carbon arc accelerated test, and the tensile strength and elongation at break were measured before and after the test. Specifically, a 1200-hour exposure test was conducted using a Sunshine Weather Meter (sometimes called a Weather-O-Meter) manufactured by Suga Test Instruments, in accordance with JIS-B-7753, at a black panel temperature of 63°C (±3°C), humidity of 50% (±5%), with rain (120-minute cycle: 102 minutes dry + 18 minutes rain).

[0061] Using the test pieces before and after the above test, the tensile strength at break and the tensile elongation at break were measured in accordance with JIS K 7127:1999 (Testing methods for tensile properties of plastics) and JIS Z 2241:2011 (Testing methods for tensile properties of metallic materials).

[0062] <Initial pressure test method> Three concrete pumping pipes from each of the Examples and Comparative Examples were connected to a concrete pump truck with joints, and a concrete pumping test was carried out under the conditions shown in Table 2. Normal concrete was used as the concrete to be pumped. When a pre-filled material was used, mortar was used as the pre-filled material. 1000 kg of the pre-filled material was introduced into the concrete pumping pipe prior to pumping the concrete, and the pre-filled material was discharged from the other end of the concrete pumping pipe, thereby adhering to the inner surface of the concrete pumping pipe. Concrete was supplied from the pump truck to the pumping pipe, and the initial pressure was 1.5 MPa and the speed was 10 m / s. 3 2m / h 3 The state of pumping was observed during pumping.

[0063] <Pressure feeding state> Under the conditions listed in Table 2, 2m 3 The pumping condition was evaluated by checking whether blockages occurred in the pumping pipe before pumping. If no blockages occurred, it was rated as "good," and if pumping could not be completed due to blockage, it was rated as "blocked."

[0064] <Visual confirmation of concrete passage position> In the pumping test, the position of the concrete inside the concrete pumping pipe was visually confirmed from outside under clear skies, and visibility was evaluated.

[0065] <Evaluation test of concrete target amount> Following the initial pumping test, a total of 5,000 m of concrete was pumped under the same conditions. 3 The pump was pumped up to 25 MPa and the following evaluations were carried out. If blockage was observed due to pumping for a long period of time, the pressure was temporarily increased to 25 MPa, and if the blockage was resolved, the pressure was returned to the original condition and pumping was continued. If the blockage was not resolved, the test was terminated at that point.

[0066] <Leaking> Under the conditions listed in Table 2, 5000m 3 Before the concrete was pumped, it was checked whether there was any leakage of concrete from the joints at the connection points of the concrete pumping pipe, and an evaluation was made to see whether any leakage had occurred.

[0067] <Properties of discharged concrete> Under the conditions listed in Table 2, 5000m 3 Before pumping, it was confirmed whether there was any change in the composition of the concrete being discharged, and the properties of the concrete being discharged were evaluated.

[0068] <Rupture prediction / bulge> Under the conditions listed in Table 2, 5000m 3 Before pumping, it was checked whether any swelling had occurred in the body of the concrete pumping pipe. If swelling was visible, pumping was continued and the amount of pumping until the relevant part burst was measured, and this was taken as the "amount that can be pumped after the body bulges."

[0069] Example 1 Ultra-high molecular weight polyethylene powder (Sunfine UH910, manufactured by Asahi Kasei Corporation) was screw extruded into a hollow cylindrical body 3 m in length. The ultraviolet absorber, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, was added at 3000 ppm (0.3% by mass) relative to the polyethylene. A helical male screw groove, as shown in Figure 3, was provided on the outer periphery of each end of the obtained cylinder to allow for the attachment of a metal coupling. The male screw groove had a pitch of 5 mm. The obtained cylinder was used as a concrete pressure pipe.

[0070] Example 2 A cylindrical body was molded in the same manner as in Example 1 except that no ultraviolet absorber was added, and used as a concrete pressure pipe.

[0071] Example 3 A cylindrical body was molded in the same manner as in Example 1, except that circumferential grooves were formed at both ends of the obtained cylindrical body to form flanges for connecting joints, as shown in Figure 4, and the cylindrical body was used as a concrete pressure pipe. The outer diameter of the grooved portion was 144 mm, the outer diameter R'2 of the end was 148 mm, and R'2 / r was 1.113.

[0072] Comparative Example 1 A commercially available steel pipe (manufactured by Linex Corporation, product name Green Line) was used as a concrete pressure pipe for comparison.

[0073] [Table 1] *1: Passed: No bursting or leakage occurs. *2: The risk of explosion is extremely high and evaluation is not possible.

[0074] [Table 2] *3: Waste material quantity: The amount of waste material used prior to pumping concrete. *4: If "Yes", the explosion can be predicted in advance and workers can evacuate from the site. On the other hand, if "No", the explosion cannot be predicted and workers are exposed to danger. [Industrial Applicability]

[0075] The concrete pressure pipe of the present invention has industrial applicability at sites where concrete is pressure-fed. [Explanation of symbols]

[0076] 1...Cylinder, 2...Flange, 10...Concrete pressure pipe, 20...Coupling, 30...Joint, 40...Male screw groove, 50...Circumferential groove, 60...Female screw groove, 70...Circumferential groove, 80...Flange

Claims

1. A concrete pumping pipe that does not include a metal pipe, It has a cylindrical body made of resin, The resin has a viscosity average molecular weight of 10×10 4 More than 1000 x 10 4 Ultra-high molecular weight polyethylene, the coefficient of dynamic friction of the inner surface of the cylindrical body is 0.07 to 0.15; The cylinder did not burst or leak in a 25 MPa water pressure test, The total light transmittance per 2 mm thick test piece of the cylindrical body is 10% or more, The contact angle of the inner surface of the cylindrical body is 55° or more. Concrete pressure pipe.

2. The amount of wear on the inner surface of the cylindrical body measured by a sand slurry wear method is 10 mg or less. A concrete pumping pipe according to claim 1.

3. the tensile breaking strength of the cylindrical body after an accelerated exposure test at a black panel temperature of 63°C ± 3°C for 1200 hours is 50% or more of the tensile breaking strength (100%) before the accelerated exposure test; The tensile breaking elongation of the cylindrical body after the accelerated exposure test is 50% or more relative to 100% of the tensile breaking elongation before the accelerated exposure test. A concrete pressure pipe according to claim 1 or 2.

4. 4. A concrete pressure pipe according to claim 1, wherein the cylindrical body has at least the innermost and outermost resin layers and has a spiral male screw groove or a circumferential groove on the outer circumferential surface at both ends.

5. The cylindrical body is a single-layer tube. A concrete pressure pipe according to any one of claims 1 to 4.

6. The total length Lw of the cylindrical body is 0.3 to 4 m. A concrete pressure pipe according to any one of claims 1 to 5.

7. The pitch of the male screw groove is 3 to 10 mm. A concrete pumping pipe according to claim 4.

8. The maximum outer diameter R' of the flange formed between the end face of the cylindrical body and the circumferential groove. 2 and the ratio R' of the inner diameter r of the cylindrical body 2 / r is 1.05 to 1.4; A concrete pumping pipe according to claim 4.

9. the cylinder further comprises an ultraviolet absorber; The content of the ultraviolet absorber is 0.01 to 10% by mass relative to the total amount of the cylindrical body. A concrete pressure pipe according to any one of claims 1 to 8.

10. Viscosity average molecular weight is 10 × 10 4 More than 1000 x 10 4 The concrete pumping pipe according to any one of claims 1 to 9 is manufactured by screw extrusion molding an ultra-high molecular weight polyethylene having the following properties into a hollow cylindrical shape. A method for manufacturing concrete pressure pipes.

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