Resin spray method

Abstract

To provide a resin spray method that enables a synthetic resin to be efficiently sprayed even when a construction range is wide because a construction object is an uneven surface.SOLUTION: In a resin spray method, a synthetic resin is sprayed on an uneven surface. The resin spray method includes: a step (step S2) of applying surface preparation to the uneven surface; a step (step S3) of making a spray machine spray a primer, which is diluted for spray, on the uneven surface subjected to the surface preparation; and a step (step S4) of spraying a polyurea resin to a primer layer on which the primer is sprayed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin spraying method for spraying a synthetic resin onto an uneven surface. [Background technology]

[0002] As disclosed in Patent Documents 1 and 2, a method of preventing the concrete surface of tunnel linings and the like from peeling off is being carried out in which a primer is applied to the surface of the lining and then a polyurethane resin is sprayed on it.

[0003] The primer is applied to the lining surface with a roller or brush to increase the adhesion between the lining surface and the polyurea resin layer. Polyurea resin is a resin containing an isocyanate component and a polyamine component, and the coating film formed by this resin has low rigidity and high elongation, making it easy to follow large deformations and suitable for preventing concrete spalling and collapse. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-160732 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-152584 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-218352 Summary of the Invention [Problem to be solved by the invention]

[0005] If the lining surface is relatively smooth, the primer can be applied efficiently using a roller. However, in cases where the mortar on the lining surface has been lost due to aging of the concrete, exposing the coarse aggregate, or in cases where the lining is finished with sprayed concrete, the lining surface is highly uneven, and the primer must be applied by brush, which is slower to apply than a roller.

[0006] Patent Document 3 describes a method of spraying a primer using a spray nozzle to repair localized areas of peeling and spalling of concrete pieces, but the primer used to increase adhesive strength has a high viscosity, and even if it is supplied to a spraying machine in its original state, it may not be applicable to spraying over a wide area.

[0007] Therefore, an object of the present invention is to provide a resin spraying method that enables synthetic resin to be sprayed efficiently even if the target surface is uneven and the application area is wide. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the resin spraying method of the present invention is a resin spraying method for spraying a synthetic resin onto an uneven surface, and includes a step of performing a base treatment on the uneven surface, a step of spraying a primer diluted for spraying onto the uneven surface after the base treatment using a spraying machine, and a step of spraying a polyurethane resin onto the primer layer onto which the primer has been sprayed.

[0009] Here, it is preferable that the primer is mainly composed of an epoxy resin and is diluted with an epoxy thinner at a dilution rate of 10% or more but less than 20%. The amount of the primer to be sprayed is 0.5 kg / m 2 Furthermore, the spray amount of the polyurethane resin is preferably 2.8 kg / m or more. 2 It is preferable that this is equal to or greater than this.

[0010] The uneven surface is preferably applied when the height difference between the protrusions and recesses is 5 mm or more.Furthermore, the uneven surface is preferably applied when it is a lining surface of a tunnel. [Effects of the Invention]

[0011] The resin spraying method of the present invention, configured as described above, involves spraying a primer diluted for spraying onto an uneven surface that has undergone a surface treatment using a spraying machine, and then spraying a polyurea resin onto the primer layer formed thereby.

[0012] Therefore, even if the target surface is uneven and the application area is large, a primer layer can be efficiently formed by supplying diluted primer for spraying to the spraying machine, allowing for quick transition to the subsequent synthetic resin spraying work, resulting in excellent application properties. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a flowchart illustrating steps of a resin spraying method according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a primer layer and a polyurea resin layer sprayed onto the uneven surface of the lining. [Figure 3] FIG. 10 is an explanatory diagram of experimental results regarding primer dilution rates. [Figure 4] 1A and 1B are diagrams illustrating a push-out test of a specimen coated with polyurethane resin, where (a) is an explanatory diagram of the test overview, and (b) is a plan view showing the area of ​​polyurethane resin applied to the substrate that serves as the specimen. [Figure 5] FIG. 10 is an explanatory diagram of the results of a push-out test on a test piece coated with a polyurethane resin. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a flow chart illustrating the steps of the resin spraying method of this embodiment, and Fig. 2 is a cross-sectional view schematically showing a primer layer 2 and a polyurethane resin layer 3 sprayed onto an uneven surface 11 of a lining 1.

[0015] The resin spraying method of this embodiment is a method for spraying synthetic resin onto uneven surfaces that are not smooth, such as surfaces where the surface concrete has deteriorated and lost mortar, exposing the coarse aggregate, or surfaces with a sprayed concrete finish.

[0016] In addition, uneven surfaces include the surfaces of brickwork, blockwork, and stonework. For example, in the case of a tunnel lining 1, the construction targets include uneven surfaces 11 where coarse aggregate is exposed due to deterioration of concrete, lining surfaces with a shotcrete finish, brickwork lining surfaces, blockwork lining surfaces, and stonework lining surfaces.

[0017] Then, as shown in Fig. 2, a primer layer 2 and a polyurea resin layer 3 are formed on the uneven surface 11 of the lining 1, which is the construction target and where peeling or collapse of the concrete is likely to occur. The polyurea resin layer 3 is formed by spraying a polyurea resin containing an isocyanate component and a polyamine component.

[0018] Polyurea resin has a tensile strength of 24N / mm 2 It has well-balanced material properties, with a tensile strength of 200%. In other words, it does not easily break even when tensile force is applied, making up for the weakness of concrete, which is its tensile strength. For this reason, spraying a thin layer of polyurethane resin onto the surface of a concrete structure can improve the structure's durability and impact resistance. Furthermore, it can also add functions to prevent concrete pieces from peeling off and water leakage.

[0019] On the other hand, a material whose main component is epoxy resin can be used as the primer for forming the primer layer 2. In the resin spraying method of this embodiment, the primer is diluted for spraying. In other words, the viscosity is reduced so that the primer can be sprayed onto the uneven surface 11 using a spray machine.

[0020] Specifically, a primer whose main component is epoxy resin is diluted with epoxy thinner. Epoxy thinners are primarily composed of aromatic hydrocarbons, alcohols, etc. If the primer is diluted with epoxy thinner to reduce its viscosity, it can be spread even to the recesses of the uneven surface 11.

[0021] On the other hand, if the primer is diluted too much, it will drip when sprayed. Therefore, in order to determine the appropriate dilution rate (viscosity), an experiment was conducted to confirm whether or not dripping occurs. Figure 3 is an explanatory diagram of the experimental results regarding the primer dilution rate.

[0022] The wall surface used in the experiment had a height difference of approximately 5 mm. Meanwhile, the dilution rates of the epoxy resin primer with epoxy thinner were set to 0%, 10%, 15%, and 20%. The viscosity of the primer without dilution (0% dilution rate) was 370 mPa·s, but by diluting it by 10% to 15%, the viscosity decreased from 55 mPa·s to 66 mPa·s, and by diluting it by 20%, the viscosity decreased to 40 mPa·s.

[0023] Then, when checking whether or not the primer dripped after spraying, it was found that no dripping occurred at dilution rates of 0%, 10%, and 15%, but that dripping only occurred when the dilution rate reached 20%. Here, whether or not dripping occurs is affected by the difference in height of the unevenness, and although this experiment was conducted only when the difference in height of the unevenness was approximately 5 mm, it is believed that this difference in height applies to an uneven surface 11 where the coarse aggregate of the concrete is exposed.

[0024] Therefore, when spraying an epoxy resin primer onto the uneven surface 11 where the coarse aggregate of the concrete lining 1 is exposed, it is desirable to dilute it with epoxy thinner to a dilution ratio of 10% or more but less than 20%. For example, the designed dilution ratio of the primer is set to a maximum of 15%.

[0025] When spraying the primer over a wide area using a sprayer, it is desirable to dilute it as described above, but when spraying it onto a smooth surface, dripping may occur even with a dilution rate of 10%. For this reason, the resin spraying method of this embodiment is intended for application to uneven surfaces.

[0026] Furthermore, when working on an uneven surface 11, it is desirable to increase the amount of primer and polyurethane resin sprayed compared to when working on a smooth surface. The reason for this is that when spraying polyurethane resin to prevent concrete spalling, it is standard practice to spray the polyurethane resin to a film thickness of 1.5 mm or more.

[0027] On the other hand, when the work is performed on an uneven surface 11, the primer and polyurethane resin penetrate into the recesses of the uneven parts, so unless the amount of spraying is increased compared to when the work is performed on a smooth surface, the film thickness after spraying may be insufficient.

[0028] Therefore, for primer, when applying to a smooth surface, the standard amount of primer to be applied is 0.2 kg / m. 2 So, 2.5 times that, 0.5kg / m 2 On the other hand, for polyurea resin, the standard spray amount when designing a smooth surface is 1.5 kg / m 2 However, it is 1.9 times that, 2.8 kg / m 2 or more, preferably 2.5 times the standard amount, 3.75 kg / m 2 Use the above as a guide to set the spray amount.

[0029] To determine the amount of increase, a test was conducted to confirm whether the specified spray thickness (1.5 mm) could be ensured by increasing the spray amount on the tunnel lining 1 with an uneven surface 11. In this test, the amount of polyurethane resin sprayed was increased to 2.8 kg / m, 1.9 times the conventional amount. 2 It was confirmed that the specified spray thickness could be secured by doing so.

[0030] Furthermore, a polyurethane resin was sprayed onto the uneven specimen, and a push-out test was performed. Figure 4 is a diagram illustrating the push-out test of a specimen coated with polyurethane resin. Figure 4(a) is an explanatory diagram showing an overview of the push-out test. Figure 4(b) is a plan view showing the area of ​​the polyurethane resin applied to the substrate that serves as the specimen.

[0031] In the push-out test, a polyurethane resin coating is formed on the underside of a rectangular substrate in plan view, as shown in Figure 4(b). In this test specimen, a 400mm x 400mm square polyurethane resin layer is formed.

[0032] On the other hand, a cylindrical cut is made in the center of the top surface of the base. This cut is stopped halfway through the base so as not to reach the polyurethane resin layer. A ball seat placed on top of the cylindrical cut is then pressed with a load cell, and vertical downward displacement during the test is measured with a displacement meter.

[0033] The push-out tests were carried out in three cases: "case 1" using a specimen with no unevenness on the underside of the base, "case 2" using a specimen with small unevenness on the underside of the base of about 1 to 2 mm, and "case 3" using a specimen with large unevenness on the underside of the base of about 5 to 8 mm. Here, in "case 2" and "case 3" with unevenness, the amount of polyurethane resin sprayed was increased to ensure the standard spray thickness (1.5 mm).

[0034] Figure 5 is an explanatory diagram of the results of the push-out test. Here, the criteria for satisfactory performance as a spalling prevention measure were that a push-out displacement of 10 mm or less could be applied with a load of 1.5 kN or more. As can be seen from this figure, it was confirmed that sufficient load-bearing performance could be ensured even for test specimens with unevenness by increasing the amount of spraying and ensuring the specified layer thickness.

[0035] Next, the steps of the resin spraying method of this embodiment will be described with reference to the flowchart of FIG.

[0036] First, in step S1, preparations are made to take measures to prevent spalling in areas on the surface of the tunnel lining 1 where the concrete has deteriorated over time or cracks have developed, which could cause pieces of concrete to peel off or collapse. Also, if there is water seeping out from the surface of the lining 1, temporary water-stopping measures are taken.

[0037] In the surface preparation in step S2, high-pressure water is sprayed onto the uneven surface 11 of the lining 1 using a water jet to remove dirt from the lining surface. This also removes aggregates and other materials that are floating and adhering to the uneven surface 11.

[0038] Next, in step S3, the primer is diluted in order to be sprayed by a spray machine. That is, the primer is diluted with epoxy thinner to reduce its viscosity, and then sprayed by the spray machine.

[0039] Specifically, a primer (main component: epoxy resin) is diluted with epoxy thinner (main components: aromatic hydrocarbon, alcohol, etc.) and supplied to a spraying machine, and the primer is sprayed by the spraying machine even into the recessed interiors of the uneven surface 11 after the surface treatment. Here, the designed dilution rate of the primer is set to a maximum of 15%, and the designed application amount is the standard amount (0.2 kg / m 2 ) 2.5 times 0.5kg / m 2 is used as a guideline.

[0040] The spraying machine used to spray the primer is small enough that one worker can carry it, consisting of a small pump, hose, and nozzle. Compared to the equipment and materials used when spraying concrete, there is no need to transport heavy objects, making it easier to apply.

[0041] Then, in step S4, a polyurethane resin is sprayed onto the primer layer 2. The amount of polyurethane resin sprayed is set to the standard amount (1.5 kg / m) of the design spray amount so that the polyurethane resin can reach the recessed interiors of the unevenness. 2) is 2.5 times the 2 The above is a guideline.

[0042] The spraying of the polyurethane resin using this spraying machine is carried out so that the film thickness of the polyurethane resin layer 3 is 1.5 mm or more. In other words, since the lining surface is an uneven surface 11 and not smooth, the amount of polyurethane resin sprayed is increased from the standard amount to ensure that the thickness after spraying is sufficient.

[0043] The spraying machine for spraying the polyurethane resin can be the same as the spraying machine for spraying the primer, or a similar small pump, hose, and nozzle that can be carried by a single worker, making it easy to work with.

[0044] In step S5, confirmation tests are conducted to check whether the polyurethane resin layer 3 at the construction target location has the specified film thickness (1.5 mm) and whether the desired load-bearing performance is exhibited by a push-out test on a test specimen.

[0045] Next, the operation of the resin spraying method of this embodiment will be described. In the resin spraying method of this embodiment configured as described above, a primer diluted for spraying is sprayed onto the rough surface 11 that has been subjected to a base treatment using a spraying machine, and then a polyurea resin is sprayed onto the primer layer 2 formed thereby.

[0046] Therefore, even if the work target is an uneven surface 11 and the work area is wide, the primer layer 2 can be formed efficiently by supplying the diluted primer for spraying to the spraying machine, so that the subsequent synthetic resin spraying work can be started quickly, resulting in excellent workability.

[0047] In addition, by increasing the amount of primer and polyurethane resin sprayed in addition to applying the primer by spraying, it is possible to ensure application speed and support performance for the flaking mass at the same level as when the lining surface is smooth, even when the lining surface becomes very uneven.

[0048] The embodiments of the present invention have been described above in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes that do not deviate from the gist of the present invention are included in the present invention.

[0049] For example, in the above embodiment, the uneven surface 11 of the tunnel lining 1 was used as an example, but this is not limited to this, and the resin spraying method of the present invention can also be applied when spraying synthetic resin onto uneven surfaces such as the walls of bridge piers and retaining walls. [Explanation of symbols]

[0050] 11: Uneven surface 2: Primer layer 3: Polyurea resin layer

Claims

1. A resin spraying method for spraying a synthetic resin onto an uneven surface, comprising: a step of performing a base treatment on the uneven surface; a step of spraying a primer diluted for spraying onto the uneven surface that has been subjected to the surface preparation using a spray machine; and spraying a polyurea resin onto the primer layer onto which the primer has been sprayed.

2. 2. The resin spraying method according to claim 1, wherein the primer is mainly composed of an epoxy resin and is diluted with an epoxy thinner at a dilution rate of 10% or more but less than 20%.

3. The amount of the primer sprayed was 0.5 kg / m 2 3. The resin spraying method according to claim 2, wherein the resin spraying method is as described above.

4. The spray amount of the polyurea resin was 2.8 kg / m 2 The resin spraying method according to any one of claims 1 to 3, characterized in that:

5. 4. The resin spraying method according to claim 1, wherein the height difference between the convex and concave portions of the convex and concave surface is 5 mm or more.

6. 4. The resin spraying method according to claim 1, wherein the uneven surface is a lining surface of a tunnel.

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