Method for vitrifying concrete members, concrete drainage structure, and vitrified repaired concrete member

Abstract

To provide a simple and efficient vitrification method for any area of a concrete member through laser irradiation, the method not requiring formation of a molten area (glass layer seed) by fixed-point laser irradiation, and also capable of localized vitrification, and furthermore capable of suppressing concrete explosion, and to provide a concrete-made drainage structure and a vitrified repairing concrete member with excellent corrosion resistance and low water permeability obtained by the vitrification method.SOLUTION: This invention relates to a method for vitrifying any area of a concrete member, wherein a surface of the concrete member is irradiated with a laser, the beam diameter of the laser on the surface being 10 to 100 μm, and the laser power being 100 to 1000 W.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for vitrifying a concrete member, and a concrete drainage structure and a vitrified-repaired concrete member obtained by the vitrification method. [Background technology]

[0002] Because laser beams have no mass, laser processing can be performed essentially noiselessly and vibration-free. This has attracted attention not only for processing and welding metal materials, but also for processing concrete materials, and investigations into the possibility of applying this technology to the construction industry have begun.

[0003] Specifically, it has been reported that when a laser is irradiated onto concrete or rock containing silica components, the silica components in the irradiated area melt and vitrify, and the use of this phenomenon is being considered for rock cutting, drilling holes in concrete materials, and surface treatment.

[0004] For example, Patent Document 1 (JP Patent Publication No. 6-80485) proposes a surface treatment method in which a surface-attaching material mainly composed of an inorganic substance is placed on the surface of a building material substrate, and the surface layer is melted by irradiating it with a laser, thereby obtaining a building material on which a strong film is formed.

[0005] The laser welding device described in Patent Document 1 above is capable of creating a strong hardened film by melting both the base material of the construction material and the surface-attached material, and is said to be able to easily form a colored hardened film on the surface of the construction material and to provide thermal and sound insulation effects on the surface of the construction material.

[0006] Furthermore, Patent Document 2 (JP Patent Publication No. 11-19785) proposes a method for drilling a hardened cement body, which is characterized by irradiating the hardened cement body with a laser to form a brittle layer that reduces the strength of the hardened cement body, and then removing the brittle layer to drill a hole.

[0007] The method for drilling hardened cement bodies described in Patent Document 2 uses a low-noise, low-vibration device to form a brittle layer with a sufficiently reduced strength in the hardened cement body to be drilled, and then the brittle layer can be removed using a low-speed mechanical or manual tool. As a result, it is possible to minimize the generation of vibration and noise during drilling, thereby improving the working environment and surrounding environment during drilling.

[0008] The present inventors also disclosed a method for manufacturing a glass bulk body using laser irradiation in Patent Document 3 (WO 2020 / 026766). The purpose of this invention is to provide a simple method for manufacturing a glass bulk body by irradiating a sand grain aggregate, rock, or concrete with a laser and continuously forming a dense glass layer in a desired region using the silica (SiO2) component contained in the sand grain aggregate, rock, or concrete as a raw material. The method for manufacturing a glass bulk body is characterized in that the sand grain aggregate, rock, and concrete contain a silica (SiO2) component, and the method includes a first step of irradiating the surface with a fixed-point laser to form a molten zone, and a second step of moving the laser irradiation position at a scanning speed that continuously expands the molten zone to form a glass layer, wherein the first and second steps are performed continuously.

[0009] In the method for manufacturing a glass bulk body described in Patent Document 3 above, a molten portion that serves as the seed of a glass layer is formed by fixed-point laser irradiation, and then the molten portion is continuously expanded by laser scanning, thereby obtaining a good glass bulk body. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 6-80485 [Patent Document 2] Japanese Patent Application Publication No. 11-19785 [Patent Document 3] International Publication No. 2020 / 026766 Summary of the Invention [Problem to be solved by the invention]

[0011] However, the construction material and its surface treatment method described in Patent Document 1 require the use of a surface attachment material whose main component is an inorganic substance whose components have been adjusted for laser irradiation, and the surface attachment material is melted by laser irradiation to coat the surface of the construction material base material. In other words, the surface treatment method described in Patent Document 1 is a method for coating an inorganic substance using laser irradiation, and does not vitrify any area of ​​a concrete member.

[0012] Furthermore, the method of drilling holes in a hardened cement body described in Patent Document 2 uses laser irradiation to form a brittle layer in the hardened cement body, which is a technology with a completely opposite direction to the method of forming a dense glass layer in any region with reduced formation of defects, etc. Furthermore, the formation of the brittle layer is limited to a narrow region corresponding to the perforation region, and there is no need to form the brittle layer continuously.

[0013] Furthermore, while the glass bulk manufacturing method described in Patent Document 3 can form a favorable vitrified region on the surface of a concrete member, it requires expanding the melted area by fixed-point laser irradiation through laser scanning, making it difficult to locally vitrify any desired region. In addition, because laser irradiation is performed on a relatively large area, it is difficult to completely suppress spalling of the concrete member, limiting the concrete members and working environments to which it can be applied. In particular, it is difficult to apply this method to existing concrete members, such as concrete drainage structures, to impart sufficient corrosion resistance. Furthermore, it is also difficult to accurately and efficiently repair cracks with openings on the surface of concrete members. In other words, there is no simple and efficient vitrification method that can be suitably used for the internal treatment of concrete drainage structures or the repair of cracks in concrete members.

[0014] In view of the above-mentioned problems in the prior art, the object of the present invention is to provide a simple and efficient vitrification method for vitrifying any region of a concrete member by laser irradiation, which does not require the formation of a molten part (a seed of a glass layer) by fixed-point laser irradiation, enables localized vitrification, and furthermore, can suppress concrete spalling. Another object of the present invention is to provide a concrete drainage structure and a vitrified-repaired concrete member that have excellent corrosion resistance and low water permeability obtained by the vitrification method of the present invention. [Means for solving the problem]

[0015] In order to achieve the above object, the inventors have conducted extensive research into methods of irradiating the surface of concrete members with a laser, and as a result have discovered that it is extremely important to control both the diameter and output of the laser beam, leading to the present invention.

[0016] That is, the present invention provides: A method for vitrifying any area of ​​a concrete member, comprising: Irradiating a laser onto the surface of the concrete member; The beam diameter of the laser on the surface is set to 10 to 100 μm, The output of the laser is 100 to 1000 W. The present invention provides a method for vitrifying a concrete member, characterized by the above.

[0017] In the method for vitrifying a concrete member of the present invention, by setting the laser beam diameter to 10 μm or more, it is possible to ensure an industrially applicable level of vitrification speed and efficiency. On the other hand, by setting the laser beam diameter to 100 μm or less, it is possible to suppress concrete spalling. The laser beam diameter is preferably 20 to 90 μm, more preferably 30 to 80 μm, and most preferably 40 to 70 μm.

[0018] Furthermore, in the method for vitrifying a concrete member of the present invention, by setting the laser output to 100 W or more for a beam diameter of 10 to 100 μm, it is possible to vitrify the concrete member in the laser scanning area without forming a molten zone (a seed of a glass layer) due to fixed-point laser irradiation. On the other hand, by setting the laser output to 1000 W or less, spalling of the concrete can be suppressed. The laser output is preferably 200 to 900 W, more preferably 300 to 800 W, and most preferably 400 to 700 W.

[0019] In the method for vitrifying a concrete member of the present invention, the power density of the laser is set to 10 to 50 MW / cm 2 It is preferable to set the power density to 10 MW / cm. 2 By setting the power density to the above level, the concrete member in the laser scanning area can be vitrified more reliably without forming a molten part (a seed of a glass layer) due to fixed-point irradiation of the laser. In addition, it is possible to ensure a vitrification speed and efficiency that is industrially applicable. Furthermore, it is possible to set the power density to 50 MW / cm 2 By setting the power density to 15-45 MW / cm or less, concrete spalling can be more reliably suppressed. 2 More preferably, it is 20 to 40 MW / cm 2 It is most preferable to set the following.

[0020] In the method for vitrifying a concrete member of the present invention, the laser scanning speed is preferably 100 to 1,000 mm / sec. By setting the laser scanning speed to 100 mm / sec or more, it is possible to ensure the speed and efficiency of vitrification and suppress spalling at the same time. Furthermore, by setting the laser scanning speed to 1,000 mm / sec or less, it is possible to stably and continuously form a vitrified region. The laser scanning speed is more preferably 300 to 800 mm / sec, and most preferably 500 to 600 mm / sec.

[0021] Furthermore, it is preferable to use a fiber laser in the method for vitrifying a concrete member of the present invention. The type of laser used in the method for vitrifying a concrete member of the present invention is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known lasers can be used, but by using a fiber laser, a beam diameter of 10 to 100 μm and a laser output of 100 to 1000 W can be easily achieved.

[0022] Furthermore, the method for vitrifying a concrete member of the present invention preferably includes a first step of identifying the position, shape, and size of a crack present on the surface of the concrete member, and a second step of irradiating the crack with the laser. When a crack exists on the surface of a concrete member, the position, shape, and size of the crack can be determined in advance in the first step, and the crack can be accurately irradiated with the laser in the second step, thereby efficiently and effectively repairing the concrete member by vitrifying the crack.

[0023] Furthermore, in the method for vitrifying a concrete member of the present invention, it is preferable that the concrete member is a concrete drainage structure, and the irradiation is performed on the upper surface of the bottom slab and / or the inner wall surface of the concrete drainage structure. By irradiating the upper surface of the bottom slab and / or the inner wall surface of the concrete drainage structure with a laser to vitrify it, a concrete drainage structure with excellent corrosion resistance can be produced very efficiently. The concrete drainage structure is not particularly limited as long as it does not impair the effects of the present invention, and can be any of various conventionally known concrete drainage structures, such as a concrete manhole, a concrete gutter, and a concrete Hume pipe.

[0024] Furthermore, for example, when lining the interior surface of an existing concrete drainage structure with plastic, dirt on the surface of the concrete member due to sludge and other contaminants and moisture inhibit adhesion, but in the concrete member vitrification method of the present invention, the surface of the concrete drainage structure is melted and vitrified together with the sludge by laser irradiation, and the moisture instantly evaporates, so these effects are hardly felt. As a result, existing concrete drainage structures can also be suitably treated.

[0025] Furthermore, in the method for vitrifying a concrete member of the present invention, the coefficient of permeability of the concrete member is set to 1×10 -7 It is preferable that the water permeability of the concrete member is 1×10 cm / s or less by vitrifying the surface of the concrete member, especially the surface having cracks. -7 By keeping the permeability of concrete components at 0.5×10 cm / s or less, it is possible to obtain concrete components with excellent reliability and long-term stability. -7 It is more preferable that the flow rate is 0.1 × 10 cm / s or less. -7 It is most preferable that the speed is equal to or less than cm / s.

[0026] The present invention also provides a concrete drainage structure characterized in that a vitrified layer is formed on at least a portion of the upper surface of the base slab and / or the inner wall surface. Note that the "vitrified layer" and "vitrified region" in this invention refer to the vitrified surface of a concrete member, and are not formed by using a glass layer made from a material other than the concrete member.

[0027] The concrete drainage structure of the present invention has a vitrified layer formed on at least a portion of the upper surface of the base slab and / or the inner wall surface, and has dramatically improved corrosion resistance compared to conventional concrete drainage structures. Here, the vitrified layer is preferably formed in an area of ​​the concrete drainage structure that is constantly in contact with acidic water.

[0028] Concrete drainage structures deteriorate when they react with acid. Furthermore, when alkaline wastewater is discharged from beverage factories and other facilities, reinforced plastic pipes and other structures are used, and in areas where it is difficult to use plastic materials, such as manholes, the concrete members must be lined with plastic to prevent the acid from acting on them. In contrast, in the concrete drainage structure of the present invention, the areas that come into contact with acidic water are covered with a glass layer that has excellent chemical stability, providing good corrosion resistance.

[0029] In the concrete drainage structure of the present invention, the thickness of the vitrified layer is preferably 100 to 20,000 μm. By making the thickness of the vitrified layer 100 μm or more, it is possible to impart extremely good corrosion resistance to the concrete drainage structure, and by making it 20,000 μm or less, it is possible to reduce the embrittlement of the concrete drainage structure and the cost of vitrification treatment. The thickness of the vitrified layer is more preferably 200 to 15,000 μm, and most preferably 300 to 10,000 μm.

[0030] The concrete drainage structure of the present invention can be suitably obtained by the method for vitrifying a concrete member of the present invention.

[0031] Furthermore, the present invention provides a concrete member having a vitrified layer formed on at least a portion of the surface thereof, the concrete member having the vitrified layer having a water permeability coefficient of 1×10 -7 The present invention also provides a vitrified repaired concrete member characterized by a viscosity of 1000 ppm or less.

[0032] The region where the vitrified layer is formed is not particularly limited as long as the effect of the present invention is not impaired. However, by forming a region having defects such as cracks into a vitrified layer, water permeation is effectively suppressed, and the water permeability coefficient is reduced to 1×10 -7 The more preferable permeability coefficient is 0.5 × 10 -7 cm / s or less, and the most preferable hydraulic conductivity is 0.1 × 10 -7 cm / s or less.

[0033] In addition, in the vitrified repaired concrete member of the present invention, the bonding strength between the vitrified layer and the concrete member is 98 N / cm 2 It is preferable that the bonding strength is 98 N / cm or more. 2 As a result of the above, the vitrified repaired concrete member can be suitably used in applications where reliability is required. [Effects of the Invention]

[0034] The method for vitrifying a concrete member of the present invention not only eliminates the need for the formation of a molten zone (a seed of a glass layer) by fixed-point laser irradiation, but also enables localized vitrification and provides a simple and efficient vitrification method that can suppress concrete spalling. Furthermore, the present invention can provide a concrete drainage structure and a vitrified-repaired concrete member that have excellent corrosion resistance and low hydraulic conductivity, which can be obtained by the vitrification method of the present invention. [Brief explanation of the drawings]

[0035] [Figure 1] 1 is a schematic diagram of a method for vitrifying a concrete member (a method for manufacturing a concrete drainage structure) according to the present invention. [Figure 2] 1 is a schematic diagram of a method for vitrifying a concrete member (a method for repairing a concrete member) according to the present invention. [Figure 3] 1 is a schematic diagram of a concrete drainage structure (vitrified concrete drainage structure) of the present invention. [Figure 4] 1 is a schematic diagram of a vitrification-repaired concrete member of the present invention. [Figure 5] 1 is a photograph showing the appearance of a concrete member used in Example 1. [Figure 6] 1 is a photograph showing the appearance of a concrete member after laser irradiation in Example 1. [Figure 7] 1 is a photograph showing the appearance of a test specimen in a hydrochloric acid resistance test in Example 1. [Figure 8] 1 is a photograph showing the appearance of a concrete member used in Example 2. [Figure 9] 10 is a photograph showing the appearance of a concrete member after laser irradiation in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0036] Representative embodiments of the method for vitrifying concrete members, concrete drainage structures, and vitrified repaired concrete members of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited to these. Note that in the following description, the same or equivalent parts will be designated by the same reference numerals, and duplicate explanations may be omitted. Furthermore, since the drawings are intended to conceptually explain the present invention, the dimensions and ratios of the components shown may differ from the actual dimensions.

[0037] (1) Method for vitrifying concrete components The method for vitrifying a concrete member of the present invention involves irradiating the surface of the concrete member with a laser to vitrify any region of the concrete member, and in addition to eliminating the need to form a molten area (a seed of a glass layer) by irradiating a fixed point with a laser, it enables localized vitrification and can also suppress concrete spalling. Below, we will explain in detail the manufacturing of a concrete drainage structure and the repair of a concrete member using the method for vitrifying a concrete member of the present invention as representative examples.

[0038] (1-1) Manufacturing of concrete drainage structures Fig. 1 is a schematic diagram showing the manufacturing of a concrete drainage structure using the method for vitrifying a concrete member of the present invention. In Fig. 1, the concrete drainage structure is a concrete manhole, and the case where it is already installed is shown.

[0039] The concrete drainage structure 2 is buried underground and is generally covered on top by a manhole 4. The concrete drainage structure 2 is also connected to a drainage pipe 6 made of vinyl chloride or the like.

[0040] By irradiating the inner surface of the concrete drainage structure 2 with a laser under conditions of a beam diameter of 10 to 100 μm and a laser output of 100 to 1000 W, it is possible to form a favorable vitrified area in the irradiated area. Even if the concrete drainage structure 2 is already installed and is connected to a drainage pipe 6 or the like, the treatment can be easily carried out by scanning with a laser from a laser oscillator 8. Note that when the treatment is carried out on the concrete drainage structure 2 at a factory, the concrete drainage structure 2 may be rotated or the like while the laser is scanned.

[0041] The laser irradiation area (vitrification area) is preferably the top surface of the bottom slab and the inner wall surface of the concrete drainage structure 2, and covers the entire area that comes into contact with water, and more preferably it is assumed to be above the designed water level in the manhole. By irradiating the top surface of the bottom slab and the inner wall surface of the concrete drainage structure with a laser to vitrify them, a concrete drainage structure with excellent corrosion resistance can be manufactured very efficiently. The concrete drainage structure is not particularly limited as long as it does not impair the effects of the present invention, and can be any of various conventionally known concrete drainage structures, such as a concrete manhole, a concrete gutter, and a concrete Hume pipe.

[0042] By setting the laser beam diameter on the surface of the concrete drainage structure 2 to 10 μm or more, it is possible to ensure an industrially applicable level of vitrification speed and efficiency, and even when treating an existing concrete drainage structure 2, it is possible to carry out the treatment only at night. On the other hand, by setting the beam diameter to 100 μm or less, it is possible to suppress concrete spalling and ensure sufficient safety even during on-site construction. The laser beam diameter is preferably 20 to 90 μm, more preferably 30 to 80 μm, and most preferably 40 to 70 μm.

[0043] Furthermore, by setting the laser output to 100 W or more for a beam diameter of 10 to 100 μm, it is possible to vitrify the concrete member in the laser scanning area without forming a molten zone (a seed of a glass layer) due to fixed-point laser irradiation. On the other hand, by setting the laser output to 1000 W or less, it is possible to suppress spalling of the concrete. The laser output is preferably 200 to 900 W, more preferably 300 to 800 W, and most preferably 400 to 700 W.

[0044] The laser power density is 10 to 50 MW / cm 2 It is preferable to set the power density to 10 MW / cm 2 By setting the power density to the above, the inner surface of the concrete drainage structure 2 in the laser scanning area can be vitrified more reliably without forming a molten part (a seed of a glass layer) due to fixed-point irradiation of the laser. In addition, it is possible to ensure a vitrification speed and efficiency that is industrially applicable. Furthermore, it is possible to set the power density to 50 MW / cm 2 By setting the power density to 15-45 MW / cm or less, concrete spalling can be more reliably suppressed. 2 More preferably, it is 20 to 40 MW / cm 2 It is most preferable to set the following.

[0045] Furthermore, the laser scanning speed is preferably 100 to 1000 mm / sec. By setting the laser scanning speed to 100 mm / sec or more, it is possible to ensure the speed and efficiency of vitrification and simultaneously suppress explosion. Furthermore, by setting the laser scanning speed to 1000 mm / sec or less, it is possible to stably and continuously form a vitrified region. The laser scanning speed is more preferably 300 to 800 mm / sec, and most preferably 500 to 600 mm / sec.

[0046] It is preferable to use a fiber laser for the laser irradiation. The type of laser used for irradiation is not particularly limited as long as it does not impair the effects of the present invention, and various conventionally known lasers can be used, but by using a fiber laser, a beam diameter of 10 to 100 μm and a laser output of 100 to 1000 W can be easily achieved.

[0047] Furthermore, the thickness of the vitrified layer formed on the inner surface of the concrete drainage structure 2 is preferably 100 to 20,000 μm. By making the thickness of the vitrified layer 100 μm or more, it is possible to impart extremely good corrosion resistance to the concrete drainage structure 2, and by making the thickness 20,000 μm or less, it is possible to reduce the embrittlement of the concrete drainage structure 2 and the cost of vitrification treatment. The thickness of the vitrified layer is more preferably 200 to 15,000 μm, and most preferably 300 to 10,000 μm.

[0048] (1-2) Repair of concrete members FIG. 2 is a schematic diagram showing a case where a concrete member is repaired using the method for vitrifying a concrete member of the present invention.

[0049] When repairing a concrete member using the method for vitrifying a concrete member of the present invention, it is preferable to have a first step of identifying the position, shape, and size of a crack 12 present on the surface of the concrete member 10, and a second step of irradiating the crack 12.

[0050] If a crack 12 exists on the surface of a concrete member 10, the position, shape, and size of the crack 12 are determined in advance in a first step, and then the crack 12 is accurately irradiated with a laser in a second step. This allows the concrete to be vitrified, thereby sealing the opening of the crack 12 and preventing rusting of the reinforcing bars 14 due to water entering through the crack 12.

[0051] The coefficient of permeability of concrete member 10 is 1 x 10 -7It is preferable that the water permeability of the concrete member 10 is 1×10 cm / s or less by vitrifying the surface of the concrete member 10, particularly by vitrifying the surface having the cracks 12. -7 By setting the permeability coefficient of the concrete member 10 to 0.5×10 cm / s or less, it is possible to obtain a concrete member 10 that is excellent in reliability and long-term stability. -7 It is more preferable that the flow rate is 0.1 × 10 cm / s or less. -7 It is most preferable that the speed is equal to or less than cm / s.

[0052] The laser irradiation conditions are the same as those for manufacturing concrete drainage structures, but the laser irradiation may be superimposed on the same area to more reliably seal the opening of the crack 12. Furthermore, since repairs to the concrete member 10 are carried out on-site, it is extremely important to reduce the time required for repairs and to prevent concrete spalling.

[0053] (2) Concrete drainage structures A schematic diagram of a concrete drainage structure (vitrified concrete drainage structure) of the present invention is shown in Figure 3. Figure 3 shows a case where the concrete drainage structure is a concrete manhole.

[0054] The vitrified concrete member 20 preferably has a vitrified area 22 formed on the upper surface of the bottom slab and the inner wall surface of the concrete drainage structure 2, and more preferably the vitrified area 22 covers the area that comes into contact with water. In addition, it is preferable that the area that comes into contact with water is assumed to be equal to or higher than the design water level in the manhole.

[0055] The formation of vitrified regions 22 on the upper surface of the base slab and the inner wall surface of concrete drainage structure 2 imparts excellent corrosion resistance to vitrified concrete member 20. The concrete drainage structure 2 is not particularly limited as long as it does not impair the effects of the present invention, and can be any of various conventionally known concrete drainage structures, such as a concrete manhole, a concrete gutter, and a concrete Hume pipe.

[0056] (3) Vitrified repair concrete members A schematic diagram of a vitrification-repaired concrete member of the present invention is shown in Figure 4. In a vitrification-repaired concrete member 30, the opening of a crack 12 that reaches the surface of a concrete member 10 is closed with a vitrified region 22.

[0057] If a crack 12 exists on the surface of a concrete member 10, the position, shape, and size of the crack 12 are determined in advance in a first step, and then the crack 12 is accurately irradiated with a laser in a second step. This allows the concrete to be vitrified, thereby sealing the opening of the crack 12 and preventing rusting of the reinforcing bars 14 due to water entering through the crack 12.

[0058] The coefficient of permeability of the vitrified repaired concrete member 30 is 1 × 10 -7 It is preferable that the water permeability of the vitrified concrete member 30 be 1×10 cm / s or less by vitrifying the surface of the concrete member 10, particularly the surface having the crack 12. -7 By setting the water permeability coefficient to 0.5×10 cm / s or less, it is possible to obtain a vitrified-repaired concrete member 30 that is highly reliable and has long-term stability. -7 It is more preferable that the flow rate is 0.1 × 10 cm / s or less. -7 It is most preferable that the speed is equal to or less than cm / s.

[0059] In addition, in the vitrified repaired concrete member 30, the bonding strength between the vitrified layer and the concrete member 10 is 98 N / cm 2 It is preferable that the bonding strength is 98 N / cm or more. 2 As a result of the above, the vitrified repaired concrete member 30 can be suitably used in applications where reliability is required.

[0060] Representative embodiments of the present invention have been described above, but the present invention is not limited to these, and various design modifications are possible, all of which are included in the technical scope of the present invention. [Example]

[0061] Example 1 Using a single-mode fiber laser, the surface of a disk-shaped concrete member having the composition shown in Table 1 was irradiated with the laser. A photograph of the appearance of the concrete member is shown in Figure 5. The laser beam diameter on the surface of the concrete member was 43 μm, and the laser output was 500 W (power density: 34.45 MW / cm). 2 The laser scanning speed was set to 260 mm / sec, and the laser was irradiated onto the entire surface of the concrete member. The laser scanning pitch was set to 0.05 mm, and fixed-point laser irradiation was not performed.

[0062] [Table 1]

[0063] A photograph of the appearance of the concrete member after laser irradiation is shown in Figure 6. It can be seen that the entire surface of the concrete member has discolored, and that the entire surface has been vitrified. The vitrified concrete member was cut for evaluation, and the three vertical lines in the photograph are due to this cutting.

[0064] To evaluate the corrosion resistance of the vitrified region, the vitrified region was crushed and separated from the concrete component and subjected to a hydrochloric acid resistance test. Specifically, the weight of the vitrified region fragments was measured in an air-dry state, and then the fragments were immersed in laboratory hydrochloric acid (10%) in a petri dish for 30 minutes to observe the reaction. Only a small amount of foaming occurred from the vitrified region fragments, confirming that the reaction was mild. The weight of the vitrified region fragments was then measured in an air-dry state after 30 minutes of immersion, and the weight change was evaluated. These evaluations were performed on five vitrified region fragments. The weight change results are shown in Table 2.

[0065] [Table 2]

[0066] For comparison, the corrosion resistance of non-vitrified concrete members was evaluated in the same manner as above. Crushed concrete pieces were immersed in laboratory hydrochloric acid (10%) for 30 minutes and the reaction status was observed. Numerous bubbles were generated from the crushed concrete pieces, indicating that the reaction was progressing vigorously. The weight change results are shown in Table 2.

[0067] Figure 7 shows photographs of the appearance of vitrified and non-vitrified concrete components before, during, and after immersion in experimental hydrochloric acid (10%). In the non-vitrified concrete components, the surface of the concrete components after immersion is roughened by dissolution, but in the vitrified concrete components, there is almost no change. Regarding the weight change shown in Table 2, there is also little change in the vitrified components, indicating that the vitrified region has extremely good corrosion resistance.

[0068] Example 2 A concrete member having a crack on its surface as shown in Figure 8 was irradiated with laser light to form a vitrified region at the opening of the crack. The composition of the concrete member was the same as in Example 1.

[0069] As a pre-process for laser irradiation, the position, shape, and size of the crack on the surface of the concrete member were identified (first step), and the laser was irradiated along the crack using the same laser irradiation conditions as in Example 1 (second step). A photograph of the appearance of the concrete member after laser irradiation is shown in Figure 9. It can be seen that a vitrified region was formed along the crack, and the opening was sealed. [Explanation of symbols]

[0070] 2. Concrete drainage structures, 4. Manhole, 6...Drain pipe, 8. Laser oscillator, 10. Concrete members, 12. Cracks, 14. Steel bars, 20. Vitrified concrete members, 22···Vitrification region, 30···Visitor repaired concrete components.

Claims

1. A method for vitrifying any area of ​​a concrete member, comprising: Irradiating a laser onto the surface of the concrete member; The beam diameter of the laser on the surface is set to 10 to 100 μm, The output of the laser is 100 to 1000 W, The power density of the laser is set to 10 to 50 MW / cm 2 ; The scanning speed of the laser is set to 100 to 1000 mm / sec. A method for vitrifying concrete members, characterized by:

2. Using a fiber laser; 2. The method for vitrifying a concrete member according to claim 1, wherein the vitrification step comprises:

3. a first step of identifying the position, shape, and size of cracks present on the surface of the concrete member; a second step of irradiating the crack; 3. The method for vitrifying a concrete member according to claim 1 or 2, wherein:

4. The concrete member is a concrete drainage structure, applying the irradiation to the top surface of the bottom slab and / or the inner wall surface of the concrete drainage structure; 4. The method for vitrifying a concrete member according to claim 1, wherein the vitrification step comprises:

5. The coefficient of permeability of the concrete member is 1 × 10 －７ cm / s or less, 5. The method for vitrifying a concrete member according to claim 1, wherein the vitrification step comprises:

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