Filler

Abstract

To provide a filler that can identify a cavity.SOLUTION: A filler 10 fills a cavity 20. The filler 10 comprises urethane foam 12 and a conductive layer 14 disposed on the surface of the urethane foam 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a filler material. [Background technology]

[0002] Patent Document 1 discloses a method of repairing cavities that have occurred in the soil by filling them with urethane foam, and then inspecting the state of the filling with the urethane foam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-86555 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the inspection of Patent Document 1, an electromagnetic wave radar is used to inspect the filling state of the cavity. However, since foamed urethane has a high porosity, it may be mistakenly recognized as a cavity. Therefore, in Patent Document 1, particles with a relatively large relative dielectric constant are added to the foamed urethane. Even so, the countermeasure is not sufficient, and the foamed urethane may be mistakenly recognized as a cavity. The present disclosure aims to provide a filler capable of identifying cavities. The present disclosure can be realized in the following form. [Means for solving the problem]

[0005] [1] A filler for filling cavities, Urethane foam, a conductive layer disposed on a surface of the urethane foam; A filler comprising: Effect of the Invention

[0006] According to the present disclosure, a filling material capable of identifying cavities can be provided. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view showing a state in which an underground cavity is filled with a filling material. [Diagram 2] FIG. 1 is a block diagram showing an electrical configuration of an inspection device. [Diagram 3] 1 is a cross-sectional view illustrating a process for inspecting the underground filling condition using an inspection device. [Figure 4] 10 is a cross-sectional view illustrating a process of inspecting the filling state using an inspection device when an underground cavity is not filled. FIG. [Diagram 5] 1A to 1C are cross-sectional views for explaining an inspection method according to an embodiment of the present invention. [Figure 6] 1 shows A-scan and B-scan when the filling material of Example 1 was used. [Figure 7] 13 shows A-scan and B-scan when the filling material of Example 7 was used. [Figure 8] 13 shows A-scan and B-scan when the filling material of Example 9 was used. [Figure 9] 2 shows A-scan and B-scan when the filling material of Example 21 was used. [Figure 10] 1 shows A scan and B scan when the filler of Comparative Example 1 was used. [Figure 11] These are A-scans and B-scans of the filled state without any voids. [Figure 12] These are A-scans and B-scans of the filled state with the cavity unfilled. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Here, a preferred example of the present disclosure is given. [2] The filler according to [1], wherein the conductive layer contains a metal and / or a conductive material.

[0009] The present disclosure will be described in detail below. In this specification, when a numerical range is described using "-", the lower limit and the upper limit are included unless otherwise specified. For example, the description "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". In this specification, the upper limit and the lower limit of each numerical range can be arbitrarily combined.

[0010] 1.Filling material A filler 10 of this embodiment is shown in Fig. 1. The filler 10 of this embodiment is a member for filling a cavity 20. The cavity 20 is, for example, an underground cavity under a paved road, an underground cavity under the foundation of a building, an underground cavity at the back of a tunnel wall, etc. The cavity 20 can occur, for example, due to aging of soil underground, disasters, etc.

[0011] The filler 10 includes a urethane foam 12 and a conductive layer 14. The conductive layer 14 is disposed on the surface of the urethane foam 12. For example, the conductive layer 14 is disposed on the surface (e.g., the upper surface) of the urethane foam 12 on the ground surface S side when the filler 10 is embedded in the cavity 20. The upper surface includes a substantially horizontal surface exposed on the upper side and a surface exposed diagonally upward. The conductive layer 14 is preferably disposed on the entire upper surface of the urethane foam 12. The conductive layer 14 may also be disposed on the surface (e.g., the lower surface) of the urethane foam 12 opposite the ground surface S.

[0012] The urethane foam 12 is, for example, an on-site foamed polyurethane foam formed by reacting two liquid raw materials, liquid A and liquid B, on-site. Liquid A contains, for example, a polyol component. Liquid B contains, for example, an isocyanate component.

[0013] The urethane foam 12 may contain, for example, a filler. The filler is, for example, one or more selected from the group consisting of carbon black, aluminum short fiber, barium titanate powder, and aluminum hydroxide powder. The particle size of the carbon black is preferably 1 μm or more and 20 μm or less. The amount of carbon black added is preferably 2.0 wt % or more and 10 wt % or less. The thickness of the aluminum short fiber is preferably 30 μm or more and 100 μm. The length of the aluminum short fiber is preferably 1 mm or more and 10 mm. The amount of the aluminum short fiber added is preferably 1.0 wt % or more and 20 wt % or less. The amount of the barium titanate powder added is preferably 1.0 wt % or more and 10 wt % or less. The amount of the aluminum hydroxide powder added is preferably 1.0 wt % or more and 10 wt % or less.

[0014] The filler preferably has a dielectric constant different from that of the polyurethane foam, and more preferably has a dielectric constant greater than that of the polyurethane foam. For reference, the approximate relative dielectric constants of various materials are shown below. Urethane foam: 1 degree Sand: 3.0-5.0 Salt: 3.0-15.0 Carbon black: 12.0-13.0 Aluminum short fiber: 1.6-1.8 Barium titanate: 1200 Aluminum hydroxide: 2.2 PVC resin: 5.8-6.4 Graphite: 12.0-13.0 Glass: 3.7-10.0 Sugar: 3 Barium nitrate: 5.9 Cellulose: 6.7-8.0 Ceramic: 4.4-7.0 Granular glass (0010): 6.32 Granular glass (0080): 6.75 Bakelite: 4.5-5.5 Rochelle salt: 100-2000 Cement powder: 5.0-10 Iron oxide: 14 ·Wed:80 The amount of filler added to the urethane foam 12 is preferably 30 vol% or less, more preferably 20 vol% or less, even more preferably 15 vol% or less, and even more preferably 10 vol% or less, relative to the urethane foam 12. The amount of filler added to the urethane foam 12 is preferably 0.1 vol% or more, more preferably 0.5 vol% or more, even more preferably 1.0 vol% or more, and even more preferably 5.0 vol% or more, relative to the urethane foam 12.

[0015] From the viewpoint of facilitating detection using electromagnetic waves, the conductive layer 14 preferably contains a metal and / or a conductive material. In the present embodiment, the conductive material does not contain a metal. The form of the conductive layer 14 is not particularly limited, but is preferably a sheet. When the conductive layer 14 contains a metal, it is preferably composed of an electromagnetic wave shielding material. As the electromagnetic wave shielding material, for example, a metal film (aluminum foil, etc.), a sheet containing metal powder, a tape with metal plating (for example, nickel plating), a wire net, a punching metal (plate-like, foil-like), a wire mesh for reinforcing concrete, etc. are adopted. The metal film is preferably a film with metal vapor deposition on both sides, for example. The metal film may be used in a cut state such as confetti-like or tape-like. The thickness of the metal film (aluminum foil, etc.) is preferably 10 μm or more and 30 μm or less. The material of the wire netting is, for example, stainless steel (SUS). The mesh shape of the wire netting is, for example, rectangular. The mesh size of the wire netting (the size of the gaps in the netting) is preferably, for example, 5 mm or more and 3 cm or less.

[0016] As the conductive material, for example, carbon is preferably used. As the conductive material, for example, carbon particles, carbon fiber, etc. can be used. As the conductive layer 14 containing the conductive material, for example, an antistatic tape, a conductive rubber sheet, etc. can be used. The antistatic tape is, for example, a static electricity removing nonwoven fabric. The antistatic tape is, for example, a tape in which carbon black is attached to polyolefin (polyethylene, polypropylene, etc.). The surface resistance value of the antistatic tape is 1.0×10 3 Ω / □ or more 1.0×10 12 The surface resistance of the conductive rubber sheet is preferably 1.0 Ω / □ or more and 1.0×10 3 Ω / □ or less is preferable.

[0017] 2. Inspection equipment The inspection device 50 (see FIG. 2) of this embodiment is a device that inspects the filling state of the filler 10 filled in the cavity 20. The inspection device 50 is configured as an electromagnetic wave transmitting and receiving device. The inspection device 50 is used for so-called electromagnetic wave radar exploration work. As shown in FIG. 2, the inspection device 50 includes a control unit 51, an electromagnetic wave transmitting and receiving unit 52, a memory unit 53, an operation unit 54, an output unit 55, and a communication unit 56.

[0018] The control unit 51 controls the entire inspection device 50. The inspection device 50 includes, for example, an MCU (Micro Processor Unit). The control unit 51 performs control based on a program stored in the storage unit 53, for example.

[0019] The electromagnetic wave transmitting / receiving unit 52 is configured as a so-called electromagnetic wave radar. The electromagnetic wave transmitting / receiving unit 52 operates under the control of the control unit 51. The electromagnetic wave transmitting / receiving unit 52 has a transmitting antenna and a receiving antenna. The transmitting antenna transmits electromagnetic waves from the ground surface toward the ground. The frequency of the electromagnetic waves is selected based on the underground depth to be measured and the required resolution, and a frequency of about 50 MHz to 1 GHz is usually used. The receiving antenna receives the reflected waves from the ground.

[0020] The storage unit 53 is configured by, for example, a semiconductor memory, etc. The storage unit 53 stores programs and the like executed by the control unit 51. The storage unit 53 stores the results received by the electromagnetic wave transmitting / receiving unit 52.

[0021] The operation unit 54 is configured to allow a user to input information through an operation of the operation unit 54. The operation unit 54 is an input interface such as a push button, a touch panel, or the like.

[0022] The output unit 55 outputs the reception results (A scan and B scan described later) by the electromagnetic wave transmitting / receiving unit 52 to the outside. The output unit 55 is configured as an image display module such as a liquid crystal display or a touch panel, and displays the reception results. The output unit 55 may be configured to print out the reception results, for example.

[0023] The communication unit 56 is configured as, for example, a communication module capable of wireless communication in a communication method conforming to a wireless LAN standard such as Wi-Fi (registered trademark), a communication module capable of accessing an Internet communication network, etc. The communication unit 56 is configured to be capable of transmitting the reception results, etc., of the electromagnetic wave transmitting / receiving unit 52 to the outside.

[0024] 3. Repair method using filler A repair method using the filler 10 of this embodiment will be described. For example, as shown in Fig. 1, a cavity 20 underground G is repaired with a filler 10. The urethane foam 12 of the filler 10 is formed by foaming a liquid (hereinafter also referred to as a mixed liquid) obtained by mixing liquid A (liquid containing a polyol component) and liquid B (liquid containing an isocyanate component).

[0025] For example, when placing the conductive layer 14 on the upper surface of the urethane foam 12, a portion of the soil (ground surface S) above the cavity 20 is removed, the mixed liquid is poured into the cavity 20, and then the conductive layer 14 can be placed on the mixed liquid. Alternatively, a sheet-like base material that will form the base of the conductive layer 14 may be laid on the bottom surface of the cavity 20, holes may be drilled in the base material, the mixed liquid may be poured under the base material, and the base material may be lifted up by the foaming pressure.

[0026] For example, when the conductive layer 14 is to be placed on the lower surface of the urethane foam 12, a sheet-like base material that will form the base of the conductive layer 14 is placed on the bottom surface of the cavity 20, and then the mixed liquid is poured onto the base material.

[0027] 4. Inspection method for filling materials A method for inspecting the filler 10 of this embodiment will be described. As shown in Fig. 3, an inspection device 50 is used to inspect the filling state of the filler 10 in the cavity 20. As shown in Fig. 3, the inspection device 50 is moved over the ground surface S to transmit and receive electromagnetic waves. The inspection device 50 emits electromagnetic waves from the ground surface S toward the underground G, and receives reflected waves from the underground G. The reflected waves from the underground G are waves reflected by the filler 10, the soil of the underground G, etc. In the present disclosure, the filling state of the filler 10 is inspected by analyzing the reflected wave in any of the following ways.

[0028] (1) Analysis method (part 1) The filling condition of the filler 10 is inspected based on the reflected wave reflected at the boundary surface B1 in the ground G (more specifically, the boundary surface between the conductive layer 14 and the soil above the conductive layer 14).

[0029] The inspection device 50 (more specifically, the control unit 51) can calculate the depth D from the ground surface S to the boundary surface B1. The depth D (unit: m) can be calculated using the following formula (1). D = (1 / 2) × T × V … (1) Here, T (unit: s) is the time it takes for an electromagnetic wave transmitted from the ground surface S to the underground G to be reflected by the boundary surface B1 and return to the ground surface S. V (unit: m / s) is the propagation speed of the electromagnetic wave, which can be calculated by the following formula (2). V = 3 × 10 8 / √ε1…(2) where ε1 is the relative dielectric constant of the soil above the conductive layer 14.

[0030] The inspection device 50 (more specifically, the control unit 51) can estimate the material of the electromagnetic wave reflecting object (the conductive layer 14). The reflectance γ, which indicates the strength of the reflection of the electromagnetic wave, can be calculated by the following formula (3). γ=(√ε1-√ε2) / (√ε1+√ε2) …(3) Here, ε2 is the relative dielectric constant of the conductive layer 14. The greater the difference between ε1 and ε2, the greater the absolute value of the reflectance γ.

[0031] In the above formula (3), when ε2 is greater than ε1, the reflectance γ becomes a negative value, and the phase of the reflected wave is inverted. For example, the dielectric constant of silica sand, which is a main component of soil, is about 2.5-3.5, the dielectric constant of dry soil is about 4-6, and the dielectric constant of wet soil is about 15-40. On the other hand, the dielectric constant of the conductor (conductive layer 14) can be considered to be ∞. Therefore, from the above formula (3), the reflectance γ of the boundary surface B1 can be calculated to be about -1. In this way, the reflectance γ becomes a negative value, and by detecting a reflected wave with a large absolute value of the reflectance γ (about -1), the existence of the boundary surface B1 can be estimated. In addition, by calculating the reflection position of such a reflected wave using the above formula (1), the position of the boundary surface B1 can be estimated.

[0032] As described above, by detecting the presence of the boundary surface B1 (the boundary surface between the conductive layer 14 and the soil above the conductive layer 14), it is possible to detect the presence of the conductive layer 14, and therefore the presence of the filler 10 including the conductive layer 14. This makes it possible to detect that the cavity 20 is filled with the filler 10.

[0033] (2) Analysis method (part 2) Depending on the type of conductive layer 14, it may be difficult to detect the reflected wave reflected at the boundary surface between the conductive layer 14 and the soil above the conductive layer 14. In this case, the filling state of the filler 10 is grasped by analyzing the reflected wave as follows. When the reflected waves are analyzed for the following four cases, the measurement results of the reflected waves are substantially the same in cases 1, 2, and 3, and cannot be distinguished from one another. In contrast, in case 4, the measurement results are different from cases 1, 2, and 3, and it can be distinguished from at least case 1, which has an unfilled cavity 20. In this way, in case 4, the filling state of the filler 10 can be grasped. An example of case 4 is Example 21 (see FIG. 8) described later. (Case 1) When the cavity 20 is not filled with the urethane foam 12 (Case 2) When the cavity 20 is filled with urethane foam 12 that does not contain a conductive filler (Case 3) When the cavity 20 is filled with urethane foam 12 containing a conductive filler (Case 4) When the cavity 20 is filled with the urethane foam 12 containing a conductive filler and the conductive layer 14 is present

[0034] 5. Effects of this embodiment The filler 10 of this embodiment is a member for filling a cavity. The filler 10 includes a urethane foam 12 and a conductive layer 14 disposed on the surface of the urethane foam 12. With such a configuration, it is possible to detect the presence of the conductive layer 14, and therefore the presence of the filling material 10 including the conductive layer 14. Therefore, it is possible to determine whether the cavity 20 is filled with the filling material 10, and the cavity 20 can be identified. In particular, the completion of cavity repair can be confirmed by non-destructive inspection without compromising the light weight and good filling properties of urethane foam. In other words, during cavity inspection, it is possible to prevent voids that have been fixed using a urethane foam filling method from being mistakenly recognized as still being cavities.

[0035] In the filling material 10 of the present embodiment, the conductive layer 14 preferably contains a metal and / or a conductive substance. With this configuration, the conductive layer 14 can reflect electromagnetic waves with high reflectance by the metal whose relative dielectric constant can be regarded as ∞ and / or the conductive material. Therefore, the presence of the filler 10 can be detected even more easily.

[0036] 6. Other embodiments The present disclosure is not limited to the embodiments described above and illustrated in the drawings, and for example, the following embodiments are also included within the technical scope of the present disclosure. (1) The conductive layer 14 may include both a metal and a conductive material. (2) Although the conductive layer 14 is shown disposed on the upper surface of the urethane foam 12, it may be disposed on the side surface of the urethane foam 12 in addition to the upper surface. (3) Although the example in which the conductive layer 14 is disposed on the entire upper surface of the urethane foam 12 has been shown, it may be disposed on only a portion of the upper surface of the urethane foam 12 . EXAMPLES

[0037] Next, the above embodiment will be described more specifically with reference to examples and comparative examples. 1.Filling material Using the inspection device and inspection method of the above embodiment, the filling state of each of the fillers in Examples 1-23 and Comparative Examples 1-5 was inspected. The fillers of Examples 1-23 and Comparative Examples 1-5 had the compositions shown in Tables 1-4.

[0038] [Table 1]

[0039] [Table 2]

[0040] [Table 3]

[0041] [Table 4]

[0042] Specific configurations of the conductive layers shown in Table 1-4 will be described below. Aluminum foil 1...Thickness: 12μm, Product number: Myfoil 12μm (manufactured by UACJ) Aluminum foil 2: Thickness: 25μm, Product number: Aluminum Tape Strong (manufactured by MonotaRO) Sheet containing metal powder...Product number: Electromagnetic wave absorbing sheet for high frequency countermeasures A4-1.0t (made by ID Create) Nickel-plated tape...Product code: Shielded cloth tape KNZ-ST50 (Kyowa Harmonet) Wire mesh 1: Material: Stainless steel (SUS), mesh opening: 2cm, wire diameter: 1φ Wire mesh 2: Material: Stainless steel (SUS), mesh opening: 6 cm, wire diameter: 0.5φ Antistatic tape…Surface resistance: 2×10 4 Ω / □, Product No.: Antistatic nonwoven fabric Denkitol (manufactured by Nippon Vilene Co., Ltd.) Conductive rubber sheet: Surface resistance: 1.2 x 10 2 Ω / □, Product No.: Conductive rubber sheet 2t CEP-2 (manufactured by Tigers Polymer)

[0043] The specific configuration of the filler contained in the urethane foam shown in Table 1-4 will be described below. Carbon black: particle size: 10μm, amount added: 4.7wt% Aluminum short fiber...Product name: KC Metal Fiber A5052 (manufactured by Kogisha), fiber thickness: 90μm, fiber length: 3mm, additive amount: 9.0wt% Barium titanate powder...Addition amount: 5.5wt% Aluminum hydroxide powder...Addition amount: 5.5wt%

[0044] For Examples 1-8 and 14-23, nine plastic bottles 212 filled with urethane foam (corresponding to the urethane foam 12 in the embodiment) and a conductive layer 214 (corresponding to the conductive layer 14 in the embodiment) were prepared separately, as shown in Fig. 5. The combination of the nine plastic bottles 212 filled with urethane foam and the conductive layer 214 was regarded as a filler. For Examples 9-13, although the arrangement of the conductive layer 214 was different, a plastic bottle similar to the plastic bottle 212 in Fig. 5 and a conductive layer similar to the conductive layer 214 in Fig. 5 were used.

[0045] A 2-liter PET resin bottle was used as the PET bottle 212. The relative dielectric constant of PET resin is about 2.9-3.0, and the relative dielectric constant of silica sand is about 2.5-3.5. Therefore, the difference in relative dielectric constant between the PET bottle 212 and the soil is small, and electromagnetic waves are unlikely to be reflected. In addition, since the PET resin bottle is thin, electromagnetic waves are unlikely to be attenuated.

[0046] For Comparative Example 1-5, nine plastic bottles 212 filled with urethane foam (corresponding to the urethane foam 12 in the embodiment, see FIG. 5) were prepared and considered as the filler.

[0047] 2. Installation of filling material Each of the fillers of Examples 1-23 and Comparative Examples 1-5 was buried in the ground G. For Examples 1-8 and 14-23, first, a hole was dug from the ground surface S to the ground G, and nine plastic bottles 212 were placed at the bottom of the hole. As shown in FIG. 5, the nine plastic bottles 212 were placed three per tier, and these tiers were stacked three times. A conductive layer 214 was placed on the three plastic bottles 212 in the top tier. Then, soil was placed on the conductive layer 214 to fill the hole. For convenience, the space in which the nine plastic bottles 212 and the conductive layer 214 are placed is referred to as a cavity 220. For Examples 9-13, first, a conductive layer 214 was placed at the bottom of the hole. Next, nine plastic bottles 212 were placed on the conductive layer 214 in the same stacked state as in Fig. 5. Then, soil was placed on the top three plastic bottles 212 to fill the hole. In Comparative Example 1-5, a hole was first dug from the ground surface S to the ground G, and nine plastic bottles 212 were placed at the bottom of the hole. Then, soil was placed on the top three plastic bottles 212 to fill the hole. For convenience, the space in which the nine plastic bottles 212 are arranged is referred to as a cavity 220. The depth D1 from the ground surface S of the bottom surfaces (bottoms of the holes) of the three bottommost PET bottles 212 was 57 cm. The depth D2 from the ground surface S of the top surfaces (position of the conductive layer 214 in Examples 1-8 and 14-23) of the three topmost PET bottles 212 was 30 cm.

[0048] 3. Testing Method The filling state of each filler of Examples 1-23 and Comparative Examples 1-5 was inspected by the inspection method described in the above embodiment. As shown in Fig. 5, the inspection device 50 was moved on the ground surface S to transmit and receive electromagnetic waves. The inspection device 50 emitted electromagnetic waves from the ground surface S toward the ground G and received the reflected waves from the ground G.

[0049] The inspection device 50 uses the data of the reflected wave from the underground G to display an A-scan (waveform on the right) and a B-scan (image on the left) as shown in Figs. 6-12. An A-scan refers to a waveform measured at a certain point, and here, the polarity and intensity of the reflected wave (waveform detected by the inspection device 50) with respect to the depth from the ground surface S at the detection position where the inspection device 50 is directly above the filling material are shown. The depth from the ground surface S is calculated by the method described in the above embodiment (the above formula (1)). A B-scan is a collection of A-scans detected at each detection position. The horizontal axis of the B-scan is the scan distance (movement distance of the inspection device 50) by the inspection device 50. In the B-scan, the polarity and intensity are converted into black and white shading values, and the stronger the reflected wave, the darker the black and white color is shown. The B-scan is the distribution of the polarity and intensity of the reflected wave on a plane perpendicular to the ground surface S, and therefore shows a pseudo-section of the underground G.

[0050] If there is a peak in the A-scan intensity on the top surfaces of the three topmost PET bottles 212 (the position of the conductive layer 214 in Examples 1-8 and 14-23), that is, at a depth D2 (30 cm) from the ground surface S, it can be inferred that there is a boundary with a large difference in relative dielectric constant at that position. This makes it possible to infer that there is either a boundary surface B3 (see FIG. 5) between the conductive layer 214 and the soil above it, a boundary surface between the urethane foam (the topmost three PET bottles 212) and the soil above it, or a boundary surface between a cavity and the soil above it at the depth D2.

[0051] The polarity (convex direction) of the A-scan peak changes depending on the relationship of the relative dielectric constant of the boundary surface where the electromagnetic wave is reflected. Specifically, when the electromagnetic wave is incident from the side with a smaller relative dielectric constant to the side with a larger relative dielectric constant, the phase of the reflected wave is inverted and the A-scan peak is convex on one side in the axial direction (for example, the peak is convex on the right side in Example 1 of FIG. 6. See the solid arrow). On the other hand, when the electromagnetic wave is incident from the side with a larger relative dielectric constant to the side with a smaller relative dielectric constant, the phase of the reflected wave is not inverted and the A-scan peak is convex on the other side in the axial direction (for example, the peak is convex on the left side in Comparative Example 1 of FIG. 10. See the dashed arrow). This makes it possible to infer the object from which the electromagnetic wave is reflected. For example, when the A-scan peak at the depth D2 is convex on the right side, it can be inferred that the electromagnetic wave is reflected by the conductive layer 214 and the boundary surface B3 thereon (see FIG. 5). On the other hand, if the peak of the A-scan at depth D2 is convex to the left, it is impossible to determine whether the electromagnetic waves are reflected by the boundary between the urethane foam (the three PET bottles 212 on the top row) and the soil above it, or the boundary between the cavity 220 and the soil above it. This is because if the relative dielectric constant of urethane foam is about 1-2 with a void ratio of about 80%, it becomes approximately the same as the relative dielectric constant of air, which is 1.

[0052] The same inspection as above was also carried out on the underground in a state where the cavity 220 was filled with soil (a state where the cavity 220 did not exist). The A-scan and B-scan of the inspection results are shown in FIG. In addition, a similar inspection was also carried out on the underground in a state where the cavity 220 was not filled with either filling material or soil (a state where the cavity 220 exists, see FIG. 4). The A-scan and B-scan of the inspection results are shown in FIG.

[0053] 6 to 12, the B-scan of the detection result has a mountain-shaped shape. This is because the time at which a reflected waveform is generated at each scan position differs depending on the difference in distance from when the inspection device 50 approaches the target (the filling material, the cavity 220, or the soil filling the cavity 220) until it moves away. Also, the mountain-shaped curve of the B-scan represents the distance to the target at each coordinate of the radar, and the top of the mountain-shaped curve represents the vertical depth.

[0054] 4.Results Based on the A-scans and B-scans of Figures 6 to 12, the inspection results (radar detectability) of the filling state of each filler of Examples 1 to 23 and Comparative Examples 1 to 5 are also shown in Tables 1 to 4. FIG. 6 shows the results of the A scan and B scan of Example 1, but the results of Examples 2-6, 8, 14-19, 22, and 23 are similar, so illustration is omitted. FIG. 7 shows the results of A-scan and B-scan in Example 7, but the results in Example 20 are similar, so illustration is omitted. FIG. 8 shows the results of A-scan and B-scan in Example 9, but the results in Examples 10 to 13 are similar, so illustration is omitted. FIG. 10 shows the results of A-scan and B-scan of Comparative Example 1, and Comparative Examples 2-5 also showed similar results, so illustration is omitted.

[0055] The results of the inspection of the filling state were evaluated according to the following criteria. A: It is clearly evident that there is no cavity. B: It is clear that there is no cavity. C: It is clearly not hollow. However, it is not possible to distinguish between the urethane foam and the soil. D: It is impossible to determine that it is not hollow (it is mistakenly recognized as hollow). Each evaluation will be explained in detail. If there is a peak in the A-scan intensity at depth D2 (the top surfaces of the top three plastic bottles 212) from the ground surface S, and the peak is convex to the right, it can be inferred that there is a conductive layer at the depth D2. Therefore, it can be inferred that the cavity 220 is filled with a filling material, and it can be clearly determined that it is not a cavity 220, resulting in an evaluation of "A." Although it is not as clear as "A", if it is clear that there is an A-scan intensity peak that is convex to the right and it can be determined that it is not a cavity 220, it is rated as "B". Also, if there is an A-scan intensity peak at depth D1 from the ground surface S (the bottom surface of the three bottommost plastic bottles 212) and this peak is convex to the left, it can be inferred that there is a conductive layer at the depth D1. Therefore, it can be inferred that the cavity 220 is filled with a filling material, and although it is not as clear as "A", it can be determined that it is not a cavity 220, it is rated as "B". If there is no A-scan intensity peak at depth D2 from the ground surface S (if no reflected waves can be detected), it can be inferred that cavity 220 is filled with soil, or that the filling material has absorbed or scattered electromagnetic waves. Therefore, it can be determined that the filling state is not clearly cavity 220, but it is not possible to distinguish whether the cavity 220 is filled with urethane foam or soil, so it is rated as "C." If there is a peak in the A-scan intensity at depth D2 from the ground surface S, and the peak is convex to the left, it is impossible to determine whether the boundary between the urethane foam (the top three plastic bottles 212) and the soil above it, or the boundary between the cavity 220 and the soil above it (see boundary B2 in FIG. 4), is located at depth D2. Therefore, it is impossible to determine whether the cavity 220 is filled with filling material, and it is impossible to determine that the cavity 220 is not filled, resulting in an evaluation of "D."

[0056] As shown in Table 4, the filling state of Comparative Example 1 was evaluated as "D." The relative dielectric constant of cavity 20, i.e., air, and the relative dielectric constant of urethane foam are both about 1. Therefore, when urethane foam containing no filler was used as the filling material, a reflected wave similar to the reflected wave when cavity 220 was present (see FIG. 12) was detected.

[0057] As shown in Table 4, the filling state of Comparative Example 2-5 was evaluated as "D". This shows that even if the urethane foam contains carbon black, aluminum short fiber, barium titanate powder, and aluminum hydroxide powder as fillers, if the filler is composed only of urethane foam, it is impossible to detect whether the cavity is filled with the filler. It was found that even with barium titanate, which has a very high relative dielectric constant (1200), a detectable electromagnetic wave reflection effect cannot be obtained with a realistic addition amount.

[0058] As shown in Table 1, in Examples 1-8, the filling state was evaluated as "A" or "B." This shows that it is possible to detect whether a cavity is filled with a filler by using aluminum foil 1, aluminum foil 2, metal powder-containing sheet, nickel-plated tape, wire mesh 1, wire mesh 2, static elimination tape, and conductive rubber sheet as the conductive layer.

[0059] As shown in Table 3, in Examples 9-20, 22, and 23, the filling state was evaluated as "A" or "B." This shows that even if the urethane foam contains carbon black, aluminum short fiber, barium titanate powder, or aluminum hydroxide powder as a filler, it is possible to detect that the cavity is filled with a filler by using aluminum foil 1, aluminum foil 2, metal powder-containing sheet, nickel-plated film tape, wire mesh 1, wire mesh 2, static electricity removal tape, or conductive rubber sheet as a conductive layer.

[0060] As shown in Table 3, in Example 21, the evaluation of the filling state was "C". Example 21 corresponds to "Case 4" in the above analysis method (part 2). Also, the case where the detection result in the case where there is an unfilled cavity shown in FIG. 12 is obtained corresponds to "Case 1". Comparative Example 1 corresponds to "Case 2". Comparative Examples 2-5 correspond to "Case 3". Example 21 gave measurement results different from Cases 1-3 (see FIG. 8), and was at least distinguishable from Case 1 in which there is an unfilled cavity (when the waveform in FIG. 12 is obtained). Thus, it was found that in Example 21, it is not possible to distinguish whether the cavity is filled with urethane foam or soil, but it is possible to detect that the cavity is filled.

[0061] As shown in Table 2, in Examples 9-13, a conductive layer was placed on the bottom surface of the urethane foam, and the filling state was evaluated as "B." That is, there was a peak in the intensity of the A-scan at a depth D1 (about 0.50 m-0.56 m) from the ground surface S (the bottom surface of the three PET bottles 212 at the bottom), and the peak was convex to the left. This shows that when a conductive layer is placed on the top surface of the urethane foam (Examples 1-6 and 8), it is possible to more effectively detect that the cavity is filled with the filling material than when a conductive layer is placed on the bottom surface of the urethane foam.

[0062] 5. Effects of the embodiment According to the above Examples 1-20, 22, and 23, it was found that by the filler comprising a urethane foam and a conductive layer (aluminum foil, sheet containing metal powder, tape with nickel plating, wire mesh, antistatic tape, conductive rubber sheet) arranged on the upper or lower surface of the urethane foam, the presence of the filler can be detected, and therefore it can be detected that the cavity is filled with the filler. Moreover, according to Example 21, it was found that by using an antistatic tape as the conductive layer and containing aluminum short fibers as a filler in the urethane foam, it was possible to confirm that the cavities were filled.

[0063] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the claims of the present disclosure. [Explanation of symbols]

[0064] 10: Filling material 12: Urethane foam 14: Conductive layer 20: Hollow 50: Inspection equipment 51: Control section 52: Electromagnetic wave transmitter and receiver 53: Storage section 54: Operation section 55: Output section 56: Communications Department 212: Plastic Bottle 214: Conductive layer 220: Hollow G: underground S: Ground surface

Claims

1. A filler for filling a cavity, Urethane foam, a conductive layer disposed on a surface of the urethane foam; A filler comprising:

2. The filler of claim 1 , wherein the conductive layer comprises a metal and / or a conductive material.

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