PC sleepers

Abstract

To provide a PC sleeper having corrosion resistance and excellent durability.SOLUTION: A PC sleeper 2 includes: concrete 17; a PC sleeper body 10 having a PC steel material 18 arranged inside the concrete 17 and applying compressive force to the concrete 17; and a coating layer 20 including a resin sheet, wherein: the coating layer 20 covers a part of an area in the PC sleeper body 10; the part of the area includes longitudinal both-end surfaces of the PC sleeper body 10 and at least one edge of an outer surface adjacent to each of the longitudinal both-end surfaces; and the area covered by the coating layer 20 on the outer surface extends from both ends in a longitudinal direction of the PC sleeper body 10 to a position overlapping at least a portion where the PC steel material 18 is arranged.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a PC sleeper. [Background Art]

[0002] Prestressed concrete sleepers (hereinafter sometimes referred to as "PC sleepers") reinforced by arranging PC steel materials inside and introducing compressive force are widely used. Regarding PC sleepers, it has been pointed out that problems such as cracking and corrosion occur, particularly in salt damage environments (Non-Patent Document 1). In order to prevent cracking and the like of PC sleepers and improve durability, Patent Document 1 proposes mixing a reinforcing agent into concrete in portions where a large stress load is applied. [Prior Art Documents] [Non-Patent Documents]

[0003] [Non-Patent Document 1] Journal of Japan Railway Civil Engineering Association, 2021.7, pp. 527-530 [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 53-116604 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] However, although the reinforcing method of Patent Document 1 is effective against cracking and the like, it cannot solve the problem of corrosion caused by salt intrusion into the interior of concrete. Furthermore, it cannot solve the problem that steel materials inside PC sleepers are corroded by electric current flowing through rails, which is likely to occur in wet environments. In view of the above circumstances, an object of the present invention is to provide a PC sleeper that is less prone to corrosion and has excellent durability. [Means for Solving the Problems]

[0006] To achieve the above objectives, the present invention employs the following configuration. [1] A prestressed concrete sleeper body having concrete and PC steel members arranged inside the concrete to impart compressive force to the concrete, It comprises a coating layer including a resin sheet, The covering layer covers a portion of the main body of the prestressed concrete sleeper, The aforementioned portion of the region includes both longitudinal ends of the prestressed concrete sleeper body and the end of at least one outer surface adjacent to each of the longitudinal ends, and the region covered by the covering layer on the outer surface extends from both longitudinal ends of the prestressed concrete sleeper body to a position that overlaps with at least the portion where the PC steel members are arranged, characterized in that the PC sleeper is a prestressed concrete sleeper. [2] A prestressed concrete sleeper body having concrete and PC steel members arranged inside the concrete and applying compressive force to the concrete, It comprises a coating layer including a resin sheet, The covering layer covers a portion of the main body of the prestressed concrete sleeper, A precast concrete sleeper, characterized in that the aforementioned portion of the area includes a surface that comes into contact with the rail. [3] The PC sleeper according to [1], wherein the portion of the region includes both longitudinal ends of the prestressed concrete sleeper body and at least two ends of the outer surfaces adjacent to each of the longitudinal ends. [4] The portion of the region includes both longitudinal ends of the prestressed concrete sleeper body and the ends of at least two outer surfaces adjacent to each of the longitudinal ends, The PC sleeper according to [1], wherein the at least two outer surfaces are two outer surfaces that are not adjacent to each other but face each other. [5] The PC sleeper according to any one of [1] to [4], wherein the resin sheet is a fiber-reinforced resin sheet in which a photocurable resin is reinforced with reinforcing fibers. [6] The PC sleeper according to any of [1] to [5], wherein the thickness of the resin sheet is 1 mm or more and 3 mm or less. [7] A PC sleeper according to any of [1] to [6], wherein the permeability of the covering layer is 0.15 g or less as specified in Annex F of JIS A 7502-2. [8] A PC sleeper according to any one of [1] to [7], wherein the amount of wear of the coating layer, measured using the apparatus described in JIS A 1452 under the following conditions, is less than the amount of wear of the mortar board. (conditions) Specimen dimensions: 50mm x 50mm Number of samples: n=3 each Abrasive material: Silicon carbide abrasive material 2C as specified in Table 6 of JIS R 6111, 4.1.2. Drop height: 65cm Total fall weight: 10kg [9] The resin sheet of the coating layer has a DC insulation resistance test result of 1 × 10⁻⁶ according to JIS E 1203. 10 A PC sleeper listed in any of [1] to [8], having an Omega or greater rating.

[10] The resin sheet of the first coating layer is a PC sleeper as described in any of [1] to [9], wherein the AC dielectric breakdown voltage test result of JIS C 2110-1 is 20kV or higher.

[11] The resin sheet of the initial coating layer is a PC sleeper described in any of [1] to

[10] , wherein the DC dielectric breakdown voltage test result of JIS C 2110-2 is 15kV or higher. [Effects of the Invention]

[0007] The PC railway sleepers of this invention are resistant to corrosion and have excellent durability. [Brief explanation of the drawing]

[0008] [Figure 1] This is a partial perspective view of a PC sleeper according to the first embodiment of the present invention. [Figure 2] This is a partial perspective view of a PC sleeper according to a second embodiment of the present invention. [Figure 3] This is a front view of a PC sleeper according to the second embodiment of the present invention. [Figure 4] It is a partial perspective view of a PC sleeper according to a third embodiment of the present invention. [Figure 5] It is a partial front view of a PC sleeper according to the third embodiment of the present invention. [Figure 6] It shows a test specimen for measuring the water permeability of a resin sheet constituting a coating layer, wherein (a) is a top view and (b) is a longitudinal sectional view. [Figure 7] It shows a test specimen for measuring the water permeability of an adhesive layer constituting a coating layer, wherein (a) is a top view and (b) is a longitudinal sectional view. [Figure 8] It is an explanatory view of a fire spread test method for a coating layer, wherein (a) is a front view and (b) is a plan view of the coating layer.

Mode for Carrying Out the Invention

[0009] [First Embodiment, Second Embodiment] FIG. 1 shows a PC sleeper 1 according to a first embodiment of the present invention. FIG. 2 also shows a PC sleeper 2 according to a second embodiment of the present invention. Each of the PC sleeper 1 and the PC sleeper 2 is constituted by a PC sleeper main body 10 and a coating layer 20 that coats a partial region of the PC sleeper main body 10. Details of the coating layer 20 will be described later.

[0010] On both end faces in the longitudinal direction of the PC sleeper main body 10 (in FIGS. 1 and 2, only the first end face 11, which is one of the end faces, is shown), four outer surfaces are adjacent to each other: a top surface 13 on which a rail 30 is placed, a bottom surface 14 that faces the ground side, a left side surface 15, and a right side surface 16. Among these four outer surfaces, the top surface 13 and the bottom surface 16 are two outer surfaces that do not adjoin each other and face each other. Further, the left side surface 15 and the right side surface 16 are two outer surfaces that do not adjoin each other and face each other. In the PC sleeper 1 and the PC sleeper 2, the region of the PC sleeper main body 10 coated with the coating layer 20 is both end faces in the longitudinal direction of the PC sleeper main body 10, and ends of at least one outer surface respectively adjacent to both longitudinal end faces.

[0011] In the PC sleeper 1 shown in Figure 1, the covering layer 20 covers the first end face 11 of the PC sleeper body 10 and the vicinity of the first end face 11 of the upper surface 13 and lower surface 14 adjacent to the first end face. Similarly, on the other end face in the longitudinal direction, which is not shown in Figure 1, the covering layer 20 covers the other end face and the vicinity of the other end face of the upper surface 13 and lower surface 14.

[0012] In the PC sleeper 2 shown in Figure 2, the covering layer 20 covers the first end face 11 of the PC sleeper body 10 and the vicinity of the first end face 11 on the left side 15 and the right side 16 adjacent to the first end face. Similarly, on the other end face in the longitudinal direction, which is not shown in Figure 1, the covering layer 20 covers the other end face and the vicinity of the other end face on the left side 15 and the right side 16.

[0013] In Figure 1, the upper surface 13 and lower surface 14 of the PC sleeper 1 are two outer surfaces adjacent to both longitudinal end faces, and these two outer surfaces are not adjacent to each other but face each other. Furthermore, the left side 15 and right side 16 of the PC sleeper 2 in Figure 2 are two outer surfaces adjacent to both longitudinal ends, and these two outer surfaces are not adjacent to each other but face each other.

[0014] In other words, in both PC sleeper 1 in Figure 1 and PC sleeper 2 in Figure 2, the area in which the covering layer 20 covers the PC sleeper body 10 is the longitudinal end faces and two outer surfaces adjacent to each of those longitudinal end faces, and these two outer surfaces are not adjacent to each other but face each other. As a result, even if both longitudinal ends are not sound and the mortar applied to the ends is about to peel off, the adhesive strength of the coating layer 20 to the two outer surfaces prevents the coating layer 20 from peeling off. Therefore, it has a significant effect in suppressing corrosion from the ends of the sleeper body.

[0015] In PC sleeper 2, the areas covered by the covering layer 20 on the left side 15 and the right side 16, and in PC sleeper 1, the areas covered by the covering layer 20 on the top surface 13 and the bottom surface 14, are preferably 2 cm or longer (length in the longitudinal direction of the PC sleeper body 10), more preferably 5 cm or longer, and even more preferably 10 cm or longer. If the length of the covering layer 20 in the longitudinal direction is above the preferred lower limit, it is easier to prevent the covering from peeling off due to concrete deterioration.

[0016] As shown in Figure 3, the PC sleeper body 10 is constructed by arranging PC steel bars 18 inside the concrete 17 to apply compressive force to the concrete 17. The PC steel material 18 may be any of the following: PC steel wire (high-strength steel with a diameter of 8 mm or less), PC steel bar (high-strength steel with a diameter of 10 mm or more), or PC steel strand (PC steel wires twisted together). Furthermore, the PC sleeper body 10 may be manufactured using either a pretensioning method or a posttensioning method.

[0017] In the PC sleeper 2, the areas covered by the covering layer 20 on the left side 15 and the right side 16 extend from both ends in the longitudinal direction of the PC sleeper body 10 (first end face 11 and second end face 12) to a position that overlaps with the portion where the PC steel members 18 are arranged, as shown in Figure 3.

[0018] Similarly, in the case of PC sleeper 1, the area covered by the covering layer 20 on the upper surface 13 and the lower surface 14 extends on both sides of the longitudinal end faces (first end face 11 and second end face 12) of the PC sleeper body 10 to a position that overlaps with the portion where the PC steel material 18 is arranged, at least from both ends in the longitudinal direction of the PC sleeper body 10.

[0019] The length over which the area covered by the covering layer 20 overlaps with the portion where the PC steel members 18 are placed (the length in the longitudinal direction of the PC sleeper body 10) is preferably 2 cm or more, more preferably 5 cm or more, and even more preferably 10 cm or more. If the length over which the covering layer 20 overlaps with the PC steel members 18 in the longitudinal direction is above the preferred lower limit, the PC steel members 18 can be easily protected, and peeling of the covering due to concrete deterioration can be easily prevented.

[0020] On the other hand, the length over which the area covered by the covering layer 20 overlaps with the portion where the PC steel members 18 are arranged (the length in the longitudinal direction of the PC sleeper body 10) is preferably 20 cm or less, more preferably 18 cm or less, and even more preferably 15 cm or less. If the length over which the covering layer 20 overlaps with the PC steel members 18 in the longitudinal direction is below the preferred upper limit, it becomes possible to extend the lifespan of the PC sleeper body 10 at a low cost.

[0021] The first end face 11 and the second end face 12 of the PC sleeper body 10 are usually coated with mortar to prevent the PC steel bars 18 from being exposed. However, since the PC steel bars 18 are reinforced up to near the surface of the first end face 11 and the second end face 12, it is thought that corrosion is likely to occur due to water penetration from these end faces.

[0022] PC sleeper 1 or PC sleeper 2 is less susceptible to corrosion and has excellent durability because the coating layer 20 suppresses moisture penetration to the first end face 11 and the second end face 12. It is preferable that the coating layer 20 is continuous without any breaks throughout. This enhances the effect of preventing moisture penetration to the first end face 11 and the second end face 12.

[0023] [Third Embodiment] Figures 4 and 5 show a PC sleeper 3 according to the third embodiment of the present invention. In Figures 4 and 5, components similar to those in the first and second embodiments are denoted by the same reference numerals as in Figures 1 to 3, and their detailed descriptions are omitted.

[0024] In Figures 4 and 5, the PC sleeper 3 is covered by the covering layer 20, which covers the rail mounting portion 31 of the PC sleeper body 10. The rail mounting portion 31 is formed in a concave shape at two locations along the length of the upper surface 13 of the PC sleeper body 10, to match the installation location of the rail 30. The bottom surface of the rail 30 is in contact with approximately the center of the bottom surface 31a of the rail mounting portion 31.

[0025] In this embodiment, the covering layer 20 of the PC sleeper 3 covers not only the portion that the rail 30 contacts, but also the entire bottom surface 31a of the rail mounting portion 31, and further covers both sides 31b in the longitudinal direction thereof. In addition, the left side 15 and right side 16 of the PC sleeper body 10 are covered by hanging down from the bottom surface 31a.

[0026] In this embodiment, the area covered by the coating layer 20 of the PC sleeper body 10 includes the surface that comes into contact with the rail 30, thereby insulating the rail 30 from the PC sleeper body 10 and preventing the PC steel material 18 inside the PC sleeper body 10 from corroding due to the current flowing through the rail 30.

[0027] Furthermore, in this embodiment, the covering layer 20 covers not only the portion that the rail 30 contacts, but also the upper parts of the left side 15 and right side 16 of the sleeper body 10, by hanging down by a length A from the bottom surface 31a of the rail mounting portion 31. Therefore, in rainy weather, it is possible to prevent short circuits between the rail 30 and both sides of the PC sleeper body 10 due to rainwater dripping.

[0028] Similarly, the covering layer 20 covers the entire bottom surface 31a of the rail mounting section 31. As a result, there are areas on both sides of the part of the bottom surface 31a that contacts the rail 30 that are covered by an extension of length B. Therefore, it is possible to prevent a short circuit between the rail 30 and the upper surface 13 of the PC sleeper body 10 due to rainwater dripping during rainy weather. In this embodiment, since both sides 31b are also covered with the coating layer 20, short circuits due to rainwater can be prevented more reliably.

[0029] Lengths A and B are preferably 2 cm or more, more preferably 5 cm or more, and even more preferably 10 cm or more. By making lengths A and B sufficiently long, short circuits caused by rainwater can be prevented more reliably, and consequently, corrosion of the PC steel material 18 inside the PC sleeper body 10 can be avoided.

[0030] [Coating layer] In any embodiment, the permeability of the coating layer 20 as defined in Annex F of JIS A 7502-2 is preferably 0.15 g or less, more preferably 0.10 g or less, and even more preferably 0.05 g or less. A value of 0.15g or less corresponds to the "Type D" value specified in the "Manual for Corrosion Inhibition and Corrosion Prevention Technologies for Sewer Concrete Structures," and is equivalent to the standard value for corrosion-preventive coatings used in environments where concrete corrosion is extremely severe. By satisfying this standard, the soundness of the concrete can be maintained for a long period of time, even in environments where corrosion is extremely accelerated.

[0031] To determine the permeability of the coating layer 20 as specified in Annex F of JIS A 7502-2, prepare the test specimen according to the method described in "a) In the case of coating-type lining method" of "F3.2 Preparation of test specimens" in Annex F. The test specimen specifically consists of a flexible plate (6 mm thick, a regular octagon inscribed in a circle with a diameter of 150 mm) as specified in JIS A 5430, with a coating layer 20 superimposed on it.

[0032] Using this test specimen, a water permeability test is performed in accordance with JIS A 1404 "7.6 (Water Permeability Test)" by applying a water pressure of 0.29 MPa for 1 hour. The difference in mass (p2-p1) between the mass p1 of the flexible plate before the water permeability test and the mass p2 of the flexible plate after wiping off the adhering water is defined as the water permeability of the coating layer 20.

[0033] In any embodiment, it is preferable that the amount of wear of the coating layer 20, measured using the apparatus described in JIS A 1452 under the following conditions, is smaller than the amount of wear of the mortar board. (conditions) Specimen dimensions: 50mm x 50mm Number of samples: n=3 each Abrasive material: Silicon carbide abrasive material 2C as specified in Table 6 of JIS R 6111, 4.1.2. Drop height: 65cm Total fall weight: 10kg

[0034] The amount of wear of the coating layer 20 is preferably 30% by mass or less of the amount of wear of the mortar board, more preferably 20% by mass or less, and even more preferably 10% by mass or less. The less wear the coating layer 20 receives, the less likely it is that the coating layer 20 will deteriorate due to wear between the flying pebbles and sand and the coating layer 20.

[0035] By covering with a coating layer 20 that has excellent wear resistance, it is possible to extend the period required for the PC steel material 18 to be exposed due to wear of the first end face 11 and the second end face 12, thereby maintaining the soundness of the PC steel material 18 and concrete 17 for a long period of time. In other words, the durability of the PC sleeper 1 or PC sleeper 2 can be improved.

[0036] Furthermore, by covering the PC sleeper 3 with a coating layer 20 that has excellent abrasion resistance, it is possible to extend the period required before the PC sleeper body 10 is exposed due to wear of the coating layer 20 at the rail mounting section 31, thereby maintaining the soundness of the PC steel 18 and concrete 17 for a long period of time. In other words, the durability of the PC sleeper 3 can be improved.

[0037] In all embodiments, the coating layer 20 is preferably flame-retardant. At a minimum, it is preferable that it satisfies the conditions of "extinction time of 30 seconds or less and fire spread range of 600 mm or less in the upper direction" as specified in the "Test Method for Flame Spread of Tunnel Repair Materials" (Test Method 738-2011) of NEXCO Test Methods Part 7 "Tunnel-Related Test Methods" (July 2017).

[0038] In all embodiments, the coating layer 20 includes a resin sheet. The coating layer 20 may be a single layer or a laminate of multiple layers. In the case of multiple layers, there may be multiple resin sheets, or other layers may be laminated on one or more resin sheets. Specifically, an adhesive layer may be provided on one side of the resin sheet. A primer layer may be provided between the resin sheet and the adhesive layer. In addition, a cover material may be provided on the outer surface of the resin sheet.

[0039] Because the coating layer 20 includes a resin sheet, the coating layer 20 can be bent to conform to the PC sleeper body 10 between the first end face 11 or the second end face 12 and the outer surface adjacent to these end faces, making it less likely for gaps to form between these surfaces. Therefore, it is easy to continuously cover these surfaces.

[0040] Various resins can be used as the resin constituting the resin sheet, including, for example, polyethylene terephthalate (PET), phenolic resin, melamine resin, epoxy resin, urea resin, polyvinyl chloride resin, vinyl ester resin, polyethylene, polypropylene, butadiene, or combinations thereof. It is preferable to select the resin considering its compatibility with the adhesive. Furthermore, from the viewpoint of improving workability on site, it is preferable that the resin is a photocurable resin that does not require a special curing procedure, and vinyl ester resin is particularly desirable.

[0041] The resin sheet constituting the coating layer 20 may be a fiber-reinforced resin sheet in which heat-resistant reinforcing fibers are woven into the resin matrix to improve abrasion resistance and ensure flame retardancy. Examples of reinforcing fibers include glass fibers and basalt fibers. Among these, glass fibers are preferred in terms of cost. The resin sheet constituting the coating layer 20 is preferably a fiber-reinforced resin sheet in which a photocurable resin is reinforced with reinforcing fibers.

[0042] In all embodiments, the thickness of the resin sheet constituting the coating layer 20 is preferably 1 mm or more and 3 mm or less, and more preferably 1 mm or more and 1.5 mm or less. If the thickness of the resin sheet is above the preferred lower limit, it will have excellent durability. If it is below the preferred upper limit, it will have excellent workability.

[0043] Furthermore, in all embodiments, it is preferable that the resin sheet constituting the coating layer 20 has excellent insulating properties. In particular, when the coating layer 20 covers an area including the surface that comes into contact with the rail 30, it is preferable that it has high insulating properties. Specifically, the DC insulation resistance test result for JIS E 1203 is 1 × 10⁻⁶. 10 It is preferable that the value be greater than or equal to Ω, and 1 × 10 12 It is more preferable that the value be greater than or equal to Ω, and 1 × 10 13 It is even more preferable that the value be Ω or greater. Furthermore, the AC dielectric breakdown voltage test result according to JIS C 2110-1 is preferably 20kV or higher, more preferably 25kV or higher, and even more preferably 30kV or higher. Furthermore, the DC dielectric breakdown voltage test result according to JIS C 2110-2 is preferably 15kV or higher, more preferably 30kV or higher, and even more preferably 45kV or higher.

[0044] The covering layer 20 preferably includes an adhesive layer for bonding the resin sheet to the PC sleeper body 10. Examples of adhesives that can be used to constitute the adhesive layer include epoxy adhesives, vinyl ester adhesives, urethane adhesives, silicone adhesives, and rubber adhesives. From the viewpoint of adhesion to concrete, vinyl ester adhesives are particularly preferred. The coating layer 20 may further have a primer layer as a base for the adhesive layer. Examples of primers that make up the primer layer include vinyl ester primers, urethane primers, epoxy primers, and silicone primers.

[0045] A cover material may be further laminated onto the outer surface of the resin sheet constituting the coating layer 20 to improve abrasion resistance. Preferably, the cover material is made of a material with excellent abrasion resistance, such as plated steel sheet, monomer-cast nylon, or urethane rubber. When forming the cover material with a coating, polyurethane resin, epoxy resin, etc., are preferred materials. When laminating cover materials, it is preferable to cover the PC sleeper body 10 with a larger surface area than other layers such as resin sheets.

[0046] [Other embodiments] The PC sleepers of the present invention are not limited to PC sleeper 1, PC sleeper 2, and PC sleeper 3, but may also be PCT sleepers having a coating layer 20 in PC sleeper 1 of the first embodiment and a coating layer 20 in PC sleeper 3 of the third embodiment. Alternatively, PCT sleepers may also be having a coating layer 20 in PC sleeper 1 of the second embodiment and a coating layer 20 in PC sleeper 3 of the third embodiment.

[0047] Furthermore, in the first embodiment, the second embodiment, and combinations thereof with the third embodiment, the covering layer 20 on the longitudinal end face of the PC sleeper body 10 may be configured to cover the ends of two adjacent outer surfaces (for example, the top surface 13 and the left side surface 15) that are adjacent to each other. Furthermore, the coating layer 20 may cover all four edges of the outer surfaces adjacent to both ends in the longitudinal direction. Alternatively, the coating layer 20 may cover the edge of one outer surface adjacent to both ends in the longitudinal direction. [Examples]

[0048] [Examples] The first end face 11 and the second end face 12 of the PC sleeper body 10, and the upper surface 13 and lower surface 14 adjacent to each end face, were covered with the covering layer 20 shown below. The length of the covering layer 20 covering the upper surface 13 and the lower surface 14 was 11 cm, and the length of the portion of the covering layer 20 that overlaps with the PC steel material 18 was 10 cm.

[0049] (Composition of the coating layer 20) The following adhesive layer was applied to the following resin sheet via the following primer layer. Resin sheet 22: A 1.5mm thick sheet made by impregnating a glass top strand mat with UV-curing vinyl ester resin. Adhesive layer 21: An adhesive whose main component is vinyl ester resin and whose hardener is an organic peroxide. Thickness: 0.1 mm. Primer layer: A two-component curing primer with a vinyl ester resin as the main component and an organic peroxide as the hardener. Thickness: 0.03 mm.

[0050] [Permeability evaluation] For each of the resin sheet 22 and adhesive layer 21 in the example, a test specimen was prepared using a test substrate (flexible plate 40 in Figures 6 and 7) as specified in "a) In the case of coating-type lining method" of Annex F of JIS A 7502-2. A water permeability test was performed in accordance with "7.6 (Water permeability test)" of JIS A 1404, with a water pressure of 0.29 MPa for 1 hour. The difference in mass of the test substrate before and after the water permeability test was determined as the amount of water permeation. The results of three measurements showed that the water permeability of both the resin sheet 22 and the adhesive layer 21 was 0.00g, confirming that the water permeability of the entire coating layer 20 was well below 0.15g.

[0051] When measuring the water permeability of the resin sheet 22, the test specimen shown in Figure 6 was used. The test specimen for measuring the water permeability of the resin sheet 22 in Figure 6 consists of a 6.0 mm flexible plate 40 to which a 150 mm diameter resin sheet 22 is attached via a 0.1 mm thick adhesive layer 21.

[0052] When measuring the water permeability of the adhesive layer 21, the test specimen shown in Figure 7 was used. The test specimen for measuring the water permeability of the adhesive layer 21 in Figure 7 was made by attaching a 150 mm diameter resin sheet 22 to a 6.0 mm flexible plate 40 via an adhesive layer 21 with a thickness of 0.1 mm, then removing the resin sheet 22 from the central 70 mm x 70 mm square area, and filling the area where the resin sheet 22 was removed with adhesive layer 21.

[0053] On the other hand, instead of the test specimens shown in Figures 6 and 7 above, a test substrate (mortar test piece with a diameter of 150 mm and a thickness of 40 mm) as specified in "b) In the case of sheet lining method" of Annex F of JIS A 7502-2 was used as the test specimen, and a water permeability test was conducted in accordance with "7.6 (Water permeability test)" of JIS A 1404, with a water pressure of 0.29 MPa applied for 1 hour. The difference in mass of the test substrate before and after the water permeability test was determined as the amount of water absorbed.

[0054] The maximum water absorption obtained from three measurements was approximately 80g, and the minimum water absorption was approximately 30g. Although there was some variation, it was confirmed that while water penetrated in units of tens of grams into uncovered mortar, covering it with the resin sheet 22 and adhesive layer 21 prevented moisture from penetrating the PC sleeper body 10.

[0055] [Abrasion resistance evaluation] The resin sheet 22 (1.5 mm thick) and mortar board (1.0 mm thick) constituting the coating layer 20 of the example were used as test specimens, and the amount of wear was measured under the following conditions using the apparatus described in JIS A 1452. The results are shown in Table 1.

[0056] (conditions) Specimen dimensions: 50mm x 50mm Number of samples: n=3 each Abrasive material: Silicon carbide abrasive material 2C as specified in Table 6 of JIS R 6111, 4.1.2. Drop height: 65cm Total fall weight: 10kg

[0057] [Table 1]

[0058] As shown in Table 1, the amount of wear on the resin sheet 22 was approximately 3% of that of the mortar board, demonstrating excellent wear resistance.

[0059] [Fire spread test] The coating layer 20 (600 mm wide x 900 mm long) of the example was attached to a calcium silicate board 51 (600 mm wide x 900 mm long x 12 mm thick), and a fire spread test was measured under the following conditions using the apparatus described in NEXCO Test Method 738-2011, "Inflammation Test Method for Tunnel Repair Materials." The results are shown in Table 2, confirming compliance with NEXCO Test Method 738-2011.

[0060] (conditions) As shown in Figure 8(a), with the coating layer 20 tilted at a 45° angle with the bottom facing downwards, the flame from the burner 52 was applied from below, with the ignition point P located 300 mm from the bottom edge of the coating layer 20. For burner 52, a gas burner "KS-N burner" manufactured by Koshin Rikagaku Seisakusho Co., Ltd. was used, and a mixture of LP gas and oxygen was burned. As shown in Figure 8(b), the temperature of the ignition point P of the burner flame was confirmed using thermocouple 53 (R-type thermocouple "S6AR16 10%RH / Ptu300RXHA5000" manufactured by Ichimura Kinzoku Co., Ltd., measurement range: 0~1400℃), and recorded using a data logger "TDS-602" manufactured by Tokyo Sokki Kenkyusho Co., Ltd.

[0061] The test procedure involved raising the flame temperature to 1200°C within 30 seconds of ignition of the burner, and then burning for 10 minutes from the time the data logger indicator reached 1200°C. After the 10-minute burning time, the flame of burner 52 was removed. The time it took for the flame from burner 52 to subside after being removed was measured using a stopwatch. Additionally, the extent of fire spread in the left-right and upward directions after 10 minutes of burning was observed. The extent of the fire spread was defined as the areas where the resin sheet was blackened or deformed due to the effects of the flames.

[0062] [Table 2]

[0063] [DC Insulation Resistance Test] The resin sheet 22 (20 mm wide x 40 mm long x 1.5 mm thick) constituting the coating layer 20 of the example was subjected to JIS E 1203 "DC insulation resistance test for synthetic sleepers" under the following conditions. The results are shown in Table 3.

[0064] (conditions) Applied voltage: 500V DC x 1 minute Condition adjustment: 20℃ × 48 hours Test equipment: High-resistance meter 4339B (manufactured by Agilent Technologies) Test specimen: Resin sheet 22 (width 20mm x length 40mm x thickness 1.5mm)

[0065] [Table 3]

[0066] [AC Dielectric Breakdown Voltage Test] The resin sheet 22 (120 mm wide x 150 mm long x 1.5 mm thick) constituting the coating layer 20 of the example was subjected to an AC dielectric breakdown voltage test according to the continuous voltage boosting method of JIS C 2110-1 "Solid electrical insulating materials - Test method for dielectric breakdown strength - Part 1: Test by application of commercial frequency AC voltage". The results are shown in Table 4.

[0067] (conditions) Test atmosphere: In oil Temperature: 23℃ Test equipment: AC / DC dielectric breakdown tester: YST-243AT-100 type Boost speed: 3kV / second

[0068] [Table 4]

[0069] [DC Dielectric Breakdown Voltage Test] A DC dielectric breakdown voltage test was performed on the resin sheet 22 (width 120 mm x length 150 mm x thickness 1.5 mm) constituting the coating layer 20 of the example, according to the continuous voltage boosting method of JIS C 2110-2 "Solid electrical insulating materials - Test method for dielectric breakdown strength - Part 2: Test by DC voltage application". The results are shown in Table 5.

[0070] (conditions) Test atmosphere: In oil Temperature: 23℃ Test equipment: AC / DC dielectric breakdown tester: YST-243AT-100 type Boost speed: 5kV / second

[0071] [Table 5]

[0072] As shown in Tables 3, 4, and 5, the resin sheet 22 constituting the coating layer 20 of the example showed good insulating properties. [Explanation of symbols]

[0073] 1~3 PC sleepers 10 PC railway sleeper bodies 11 First end surface 12 Second end face 13 Top side 14 Bottom side 15 Left side 16 Right side 17 Concrete 18 PC steel material 20 Covering layer 21 Adhesive layer 22 Resin sheet 30 rails 31 Rail mounting section 40 Flexible board 51 Calcium silicate board 52 burners 53 Thermocouples

Claims

1. A prestressed concrete sleeper body having concrete and PC steel members arranged inside the concrete to impart compressive force to the concrete, It comprises a coating layer including a resin sheet, The covering layer covers a portion of the main body of the prestressed concrete sleeper, The aforementioned partial region includes both longitudinal ends of the prestressed concrete sleeper body and at least one end of the outer surface adjacent to each of the longitudinal ends, and the region covered by the covering layer on the outer surface extends from both longitudinal ends of the prestressed concrete sleeper body to a position overlapping with at least the portion where the PC steel members are arranged. The aforementioned resin sheet is a fiber-reinforced resin sheet containing a glass mat, characterized in that it is a PC sleeper.

2. A prestressed concrete sleeper body having concrete and PC steel members arranged inside the concrete to impart compressive force to the concrete, It comprises a coating layer including a resin sheet, The covering layer covers a portion of the main body of the prestressed concrete sleeper, The aforementioned portion of the region includes a surface that contacts the rail, The aforementioned resin sheet is a fiber-reinforced resin sheet containing a glass mat, characterized in that it is a PC sleeper.

3. The PC sleeper according to claim 1, wherein the aforementioned portion of the region includes both longitudinal ends of the prestressed concrete sleeper body and the ends of at least two outer surfaces adjacent to each of the longitudinal ends.

4. The aforementioned portion of the region includes both longitudinal ends of the prestressed concrete sleeper body and the ends of at least two outer surfaces adjacent to each of the longitudinal ends, The PC sleeper according to claim 1, wherein the at least two outer surfaces are two outer surfaces that are not adjacent to each other but face each other.

5. The PC sleeper according to claim 1 or 2, wherein the resin sheet is a fiber-reinforced resin sheet in which a photocurable resin is reinforced with a glass mat.

6. The PC sleeper according to claim 1 or 2, wherein the thickness of the resin sheet is 1 mm or more and 3 mm or less.

7. The PC sleeper according to claim 1 or 2, wherein the permeability of the coating layer, as specified in Annex F of JIS A 7502-2, is 0.15 g or less.

8. The PC sleeper according to claim 1 or 2, wherein the amount of wear of the coating layer, measured under the following conditions using the apparatus described in JIS A 1452, is smaller than the amount of wear of the mortar board. (conditions) Specimen dimensions: 50 mm x 50 mm Number of samples: n=3 each Abrasive material: Silicon carbide abrasive material 2C as specified in Table 6 of JIS R 6111, 4.1.

2. Drop height: 65 cm Total fall weight: 10 kg

9. The aforementioned resin sheet has a DC insulation resistance test result of 1 × 10⁻⁶ according to JIS E 1203. １０ A PC sleeper according to claim 1 or 2, wherein the impedance is Ω or greater.

10. The PC sleeper according to claim 1 or 2, wherein the resin sheet has an AC dielectric breakdown voltage test result of 20 kV or more according to JIS C 2110-1.

11. The PC sleeper according to claim 1 or 2, wherein the resin sheet has a DC dielectric breakdown voltage test result of 15 kV or more according to JIS C 2110-2.

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