Method for removing salt from construction member

Abstract

To provide a method for removing salt from a construction member that enables the rapid removal of salt from construction members.SOLUTION: The method for removing salt from a construction member 20 according to the present invention is a method for removing salt from the construction member 20 after the hardened cement body adhering to the construction member 20 has been removed by acid immersion, and includes a removal step of removing salt from the construction member 20 by immersing the construction member 20 in water W at a temperature higher than room temperature and lower than the boiling point for a predetermined period of time, and in the removal step, the water W is replaced multiple times within 72 hours from the start of the removal step.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for removing salt from construction members. [Background technology]

[0002] A technique has been proposed for reusing building materials removed from exterior walls, in which the building materials to which the hardened cement body is attached are immersed in an acid solution to remove the hardened cement body (see, for example, Patent Document 1). After removing the hardened cement body, the building materials are immersed in water at room temperature for about 20 days to remove salt from the building materials. This makes it possible to avoid poor adhesion of the building materials when they are reused. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-199458 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned conventional technology, as described above, after removing the hardened cement body, the building materials are immersed in water at room temperature for about 20 days, which takes a very long time to remove the salt from the building materials. Therefore, there is room for improvement in terms of speeding up the removal of salt from construction members such as building materials.

[0005] The present invention has been made in consideration of the above, and has an object to provide a method for removing salt from construction members, which makes it possible to speed up the removal of salt from construction members. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the method for removing salt from a construction member described in claim 1 includes a removing step of removing salt from the construction member after a hardened cement body adhering to the construction member has been removed by acid immersion, by immersing the construction member in water at a temperature higher than room temperature and lower than the boiling point for a predetermined period of time.

[0007] A method for removing salt from a construction member according to a second aspect of the present invention is the method for removing salt from a construction member according to the first aspect of the present invention, wherein in the removing step, the water is replaced multiple times within 72 hours from the start of the removing step.

[0008] A method for removing salt from construction materials described in claim 3 is the method for removing salt from construction materials described in claim 2, wherein the temperature of the water is approximately 80°C to 95°C, and the specified period is at least three days or more.

[0009] The method for removing salt from construction materials described in claim 4 is a method for removing salt from construction materials described in any one of claims 1 to 3, in which the amount of water in the removal process is approximately three times the minimum amount required for one piece of the construction material to be completely immersed in the water. Effect of the Invention

[0010] According to the method for removing salt from construction materials described in claim 1, the method includes a removal step of removing salt from the construction materials by immersing the construction materials in water at a temperature higher than room temperature and lower than the boiling point for a predetermined period of time. Therefore, compared to the conventional technology (technique of immersing building materials in water at room temperature), salt can be removed from the construction materials more effectively, and it is possible to speed up the removal of salt from the construction materials.

[0011] According to the method for removing salt from construction materials described in claim 2, in the removal process, the water is replaced multiple times within 72 hours from the start of the removal process, thereby accelerating the removal of salt from the construction materials and shortening the time required for the removal process (i.e., the immersion time of the construction materials).

[0012] According to the method for removing salt from construction materials described in claim 3, the water temperature is approximately 80°C to 95°C, and the specified period is at least three days or more, so that the salt in the construction materials can be removed to below the threshold value within a period of at least three days or more, making it possible to further shorten the time required for the removal process.

[0013] According to the method for removing salt from construction materials described in claim 4, the amount of water used in the removal process is approximately three times the minimum amount required for one construction material to be completely immersed in water, thereby making it possible to effectively remove salt from the construction materials and further accelerating the removal of salt from the construction materials. [Brief description of the drawings]

[0014] [Figure 1] 1A and 1B are diagrams conceptually showing a body according to an embodiment of the present invention, in which (a) is a front view and (b) is a cross-sectional view taken along the line AA. [Diagram 2] FIG. 1 is a diagram showing the preparatory steps of a method for removing salt from construction materials. [Diagram 3] FIG. 2 is a diagram showing the removal process of the method for removing salt from construction materials. [Figure 4] FIG. 1 is a diagram showing details of a test specimen for the first salt removal confirmation test. [Diagram 5] FIG. 1 is a diagram showing the test results of a first salt removal confirmation test. [Figure 6] FIG. 13 is a diagram showing the test results of the second salt removal confirmation test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the method for removing salt from a construction member according to the present invention will be described in detail with reference to the accompanying drawings. First, [I] the basic concept of the embodiment will be described, then [II] the specific content of the embodiment will be described, and finally, [III] modified examples of the embodiment will be described. However, the present invention is not limited to the embodiment.

[0016] [I] Basic Concept of the Embodiment First, a basic concept of the embodiment will be described. The embodiment generally relates to a salt removal method for removing salt from a construction member after a hardened cement body adhering to the construction member has been removed by acid immersion.

[0017] Here, the specific structure and type of "construction material" are arbitrary, but the concept includes, for example, exterior materials (e.g., tile-based exterior materials, brick-based exterior materials) and interior materials (e.g., tile-based interior materials, brick-based interior materials) that are attached to the framework of a structure (e.g., pillars, walls, floors, or ceilings), but in the embodiment, it will be described as a tile-based exterior material for walls.

[0018] Furthermore, the specific structure and type of the "structure" are arbitrary, but the concept includes, for example, architectural structures such as office buildings, commercial facilities, public facilities, and collective housing such as apartments and condominiums, as well as civil engineering structures such as tunnels and dams, but in the embodiment, it will be described as an office building.

[0019] In addition, the term "cement hardened body" refers to a material used to attach construction components to the main structure described below, and is a concept that includes, for example, a base material that contains at least cement as an ingredient. In the embodiment, it is described as a base material made of mortar.

[0020] Furthermore, the specific structure and type of "salt" are arbitrary, but the concept includes salts such as sodium chloride, magnesium sulfate, calcium sulfate, and bicarbonate.

[0021] Furthermore, the specific use of the construction material from which the salt has been removed by this salt removal method is arbitrary, but examples include reusing the construction material as an exterior or interior material on the framework of the structure to which it was attached or on the framework of a different structure, or using it for purposes other than exterior or interior materials (such as fencing material for flower beds, for example).

[0022] [II] Specific Contents of the Embodiments Next, the specific contents of the embodiment will be described.

[0023] (composition) First, the configuration of the framework of a structure (specifically, an office building) including construction members to which a method for removing salt from construction members according to an embodiment of the present invention is applied will be described.

[0024] FIG. 1 is a diagram conceptually showing a body according to an embodiment of the present invention, where (a) is a front view and (b) is a cross-sectional view taken along the line AA.

[0025] In the following explanation, the X direction in FIG. 1 is referred to as the left-right direction of the body (-X direction is the left direction of the body, and +X direction is the right direction of the body), the Y direction in FIG. 1 is referred to as the front-back direction of the body (+Y direction is the front direction of the body, and -Y direction is the rear direction of the body), and the Z direction in FIG. 1 is referred to as the up-down direction of the body (+Z direction is the top direction of the body, and -Z direction is the bottom direction of the body).

[0026] The skeleton 1 is a wall (eg, an exterior wall) that constitutes a structure, and includes a skeleton main body 10, construction members 20, and a hardened cement body 30, as shown in FIG.

[0027] (Structure - Main body) The main body 10 is the basic structure of the main body 1. The main body 10 is formed of a long rectangular plate made of, for example, concrete (for example, reinforced concrete or prestressed concrete), and as shown in Fig. 1, is arranged so that the longitudinal direction is along the vertical direction, and is fixed to an installation target (for example, a floor part, etc.) not shown.

[0028] (Composition - Construction Materials) The construction member 20 is constructed, for example, using a known tile-based exterior material, and as shown in Figure 1, is arranged outside the structural body 10 so as to cover the entire outer surface of the structural body 10 (in Figure 1, the entire front surface), and comprises a construction member main body 21 and a surface film 22.

[0029] (Configuration - Construction material - Construction material body) The construction member body 21 is the basic structure of the construction member 20. This construction member body 21 is made of, for example, a known tile material (one example is a rectangular tile material having a tile portion and a joint portion), and as shown in Fig. 1, a plurality of construction member bodies 21 are arranged side by side substantially along the left-right direction so as to cover the framework body 10, and a plurality of construction member bodies 21 are arranged side by side substantially along the up-down direction.

[0030] In addition, the specific configuration of the construction member body 21 in this embodiment is as follows.

[0031] That is, as shown in Fig. 1, the entire outer surface of the construction member body 21 (the entire front surface in Fig. 1) is formed flat. However, this is not limited to this, and it may be formed non-flat, for example. Also, the entire inner surface of the construction member body 21 (the entire rear surface in Fig. 1) is formed non-flat, specifically, formed to have multiple convex portions that protrude rearward.

[0032] (Configuration-Construction materials-Surface membrane) The surface film 22 is a film coated with a glaze. As shown in Fig. 2 described later, the surface film 22 is provided on the entire outer surface of the construction member body 21, and specifically, for example, the surface film 22 is formed by coating the entire outer surface of the construction member body 21 with a glaze for an exterior tile material and baking it.

[0033] Here, "glaze" refers to a chemical used to enhance the decorativeness and strength of the construction member 20 and to prevent the construction member 20 from becoming dirty. Specifically, the glaze is a chemical composed of an RO2 component (e.g., SiO2 component, etc.) that forms the skeleton of the glaze, an R2O3 component (e.g., Al2O3 component, etc.) that bonds the construction member body 21 and forms part of the skeleton of the glaze, RO components (CaO component, MgO component) that partially destroy the skeleton of the glaze and lower the melting temperature, and R2O components (Na2O component, K2O component, etc.).

[0034] Furthermore, the specific type of "glaze" is arbitrary, but examples include "transparent glaze" which is non-crystalline, "matte glaze / devitrified glaze" which contains fine crystals not incorporated into the non-crystalline, "crystalline glaze" which contains large crystals, and "milky glaze" which has multiple non-crystalline phases.

[0035] (Structure: Hardened cement body) The hardened cement body 30 is for attaching the construction member 20 to the structural body 10. The hardened cement body 30 is made of, for example, a known mortar base material, and is provided between the structural body 10 and the construction member body 21 as shown in Fig. 1, and more specifically, is provided so as to cover the entire outer surface of the structural body 10.

[0036] (Salt removal method) Next, a method for removing salt from the construction member 20 according to the embodiment will be described.

[0037] Fig. 2 is a diagram showing a preparation process of the method for removing salt from the construction member 20. Fig. 3 is a diagram showing a removal process of the method for removing salt from the construction member 20.

[0038] The method for removing salt from a construction member 20 according to the embodiment is a method for removing salt from the construction member 20 after the hardened cement body 30 adhering to the construction member 20 has been removed by acid immersion, and includes a preparation step and a removal step, as shown in Figures 2 and 3.

[0039] The reason for removing salt from the construction member 20 is as follows: If the construction member 20 from which the hardened cement body 30 has been removed by acid immersion is reused as is, there is a risk that the mortar or adhesive will not adhere sufficiently to the construction member 20 due to calcium chloride produced by the reaction between the mortar newly attached to the construction member 20 and the acid remaining in the construction member 20. This is to avoid such a problem.

[0040] (Salt removal method - preparation process) First, the preparation process will be described.

[0041] The preparation process is a process for preparing the construction member 20 for removing salt.

[0042] Specifically, as shown in FIG. 2, first, a portion of the construction member 20 is cut together with the hardened cement body 30 using a known cutting tool (not shown), and then the cut construction member 20 and the hardened cement body 30 are peeled off from the structural body 10 using a known peeling tool (not shown).

[0043] Next, the peeled construction member 20 and hardened cement body 30 are immersed in an acid solution (e.g., a solution containing hydrochloric acid, nitric acid, sulfuric acid, or citric acid) contained in a container not shown for a predetermined period of time (e.g., about one to two weeks).

[0044] Next, the immersed construction member 20 is taken out of the container, and then the hardened cement body 30 is removed by spraying cleaning water onto the hardened cement body 30 or by peeling off the hardened cement body 30 with a tool such as a brush or by hand. Then, the construction member 20 from which the hardened cement body 30 has been removed is dried at a predetermined temperature (e.g., 105°C) for a predetermined time (e.g., 1 hour).

[0045] (Salt removal method - removal process) Next, the removal step will be described.

[0046] The removal process is a process of removing salt from the construction members 20 after the preparation process by immersing the construction members 20 in water W at about 80° C. for a predetermined period of time.

[0047] 3, within a predetermined time (e.g., within one hour) from the end of the preparation process, the construction members 20 are placed in a container 50 placed in a thermostatic bath 40 and containing water W (e.g., fresh water), and while maintaining the temperature inside the thermostatic bath 40 at a temperature higher than room temperature and lower than the boiling point, the placed construction members 20 are immersed in the water W for a predetermined period of time. This promotes exchange of the water W with water with a high salt concentration inside the construction members 20, thereby removing the salt from the construction members 20.

[0048] Here, "a temperature higher than room temperature and lower than the boiling point" means a temperature of approximately 40°C to 95°C based on the test results of the first salt removal confirmation test described below, and in this embodiment, the temperature is set to approximately 80°C to 95°C in order to shorten the time required for the removal process.

[0049] The reason why the temperature of the water W is set to "a temperature higher than room temperature and lower than the boiling point" is as follows: If the temperature of the water W is set to the boiling point (specifically, about 100°C), the water W in the container 50 evaporates, so it is necessary to frequently add water W to the container 50, which is troublesome and may make it difficult to maintain the temperature of the water W at the boiling point. Therefore, this is to effectively remove salt from the construction member 20 while avoiding such problems.

[0050] In addition, the details of the removal process have been implemented as described below.

[0051] (Salt removal method - removal process - composition of construction materials) First, the details of the configuration of the construction member 20 used in the removal step are arbitrary, but in this embodiment, they are set as follows.

[0052] That is, the shape of the construction member 20 is set to a plate-like body having a substantially rectangular planar shape. However, the shape is not limited to this, and may be set to, for example, a plate-like body having a shape other than a substantially rectangular shape (for example, a substantially triangular plate-like body) or a shape other than a plate-like body (for example, a block-like body).

[0053] In addition, either the width or the length of the construction member 20 is set to 108 mm or less. However, this is not limited to this, and for example, it may be set to a length greater than 108 mm. In addition, the other of the width or the length of the construction member 20 is set to 60 mm or less. However, this is not limited to this, and it may be set to a length greater than 60 mm.

[0054] (Salt removal method - removal process - amount of water) Moreover, the amount of water W contained in the container 50 in the removal process is set to about three times the minimum amount necessary for one construction member 20 to be completely immersed in the water W. Specifically, based on the test results of the second salt removal confirmation test described below, the amount is set to about 500 ml per one construction member 20 (in this case, the minimum amount necessary for one construction member 20 to be completely immersed in the water W is about 166 ml).

[0055] This allows the desalting of the construction members 20 to be carried out effectively, and promotes the desalting of the construction members 20.

[0056] However, the amount is not limited to this, and may be set to, for example, less than 500 ml or more than 500 ml.

[0057] (Salt removal method - removal process - water replacement) Furthermore, the water W in the container 50 in the removal step is replaced multiple times within 72 hours from the start of the removal step.

[0058] Specifically, based on the test results of the first salt removal confirmation test described later, the water W is replaced three times within 72 hours from the start of the removal process. More specifically, it is replaced once a day.

[0059] This can promote the removal of salt from the construction members 20, and can shorten the time required for the removal process (that is, the immersion time of the construction members 20).

[0060] However, the present invention is not limited thereto, and the removal step may be performed less than 9 times or may be performed 10 times or more within 72 hours from the start of the removal step. Alternatively, replacement of the water W may be omitted.

[0061] (Salt removal method - removal process - soaking time) The immersion time of the construction material 20 in the removal step is set to at least three days or more based on the test results of the first salt removal confirmation test described below, and specifically, is set to three days.

[0062] This makes it possible to remove the salt content of the construction members 20 to below the threshold value in a period of at least three days or more, and further shortens the time required for the removal process.

[0063] However, the present invention is not limited to this and may be set to a period of, for example, four days or more, or may be set to a period of less than three days.

[0064] This salt removal method can remove salt from the construction material 20 more effectively than the conventional technique (technique of soaking the construction material in water at room temperature), and can speed up the removal of salt from the construction material 20.

[0065] (Test Results) Next, the results of various tests conducted by the applicant of the present invention will be described. Here, the results of the first salt removal confirmation test and the second salt removal confirmation test will be described.

[0066] (Test results - First salt removal confirmation test - Summary) First, an outline of the first salt removal confirmation test will be described. Fig. 4 is a diagram showing details of a test specimen for the first salt removal confirmation test.

[0067] The first salt removal confirmation test is a test to confirm the state of salt removal of each test specimen according to various test conditions.

[0068] The test method for the first salt removal confirmation test is arbitrary, but is as follows: Each test specimen is placed in each container 50 containing water W (fresh water), and each test specimen is immersed for 17 days while replacing the water W in the container 50. In addition, the chloride ion concentration of each test specimen is measured at predetermined timings during the above immersion (specifically, at timings 3 days, 10 days, and 17 days after the start of immersion, and before replacing the water W in the container 50).

[0069] Here, the temperature of the water W in the container 50 is set to 20°C for test specimens A1 and A2 described later, 40°C for test specimens A3 and A4 described later, 60°C for test specimens A5 and A6 described later, 80°C for test specimens A7 and A8 described later, and 95°C for test specimens A9 and A10 described later.

[0070] The water W in the container 50 is replaced in the following manner. That is, for specimens A1, A3, A5, A7, and A9 described below, the water is replaced 3 days and 10 days after the start of immersion (i.e., replaced a total of two times). For specimens A2, A4, A6, A8, and A10 described below, the water is replaced 1 day, 2 days, 3 days, and 10 days after the start of immersion (i.e., replaced a total of four times).

[0071] The test specimens used in the first salt removal confirmation test are divided into test specimens A1 to A10, as shown in FIG.

[0072] Here, specimens A1 to A10 are specimens made of tile materials (construction members 20) that are relatively difficult to remove salt from and that have been immersed in acid for a predetermined period of time.

[0073] (Test results - First salt removal confirmation test - Details of test results) Next, the test results of the first salt removal confirmation test will be described in detail. Fig. 5 is a diagram showing the test results of the first salt removal confirmation test.

[0074] As shown in Figure 5, it was confirmed that the chloride ion concentration of specimens A1 to A10 decreased as time passed. In particular, it was confirmed that the chloride ion concentrations of specimens A3, A5, A7, and A9 at the immersion time of 17 days were lower than that of specimen A1, and that the chloride ion concentrations of specimens A4, A6, A8, and A10 were lower than that of specimen A2.

[0075] In addition, for test specimens A8 and A10, it was confirmed that the chloride ion concentration was below the threshold value (specifically, less than 200 ppm) after the immersion time of 3 days, and that the chloride ion concentration was below the threshold value (specifically, less than 50 ppm) after the immersion time of 10 days.

[0076] From the above, it was confirmed that it is effective to set the temperature of the water W in the container 50 to a temperature higher than room temperature and lower than the boiling point. It was also confirmed that it is effective to set the temperature of the water W in the container 50 to about 80°C to 95°C, to replace the water W in the container 50 multiple times within 72 hours from the above immersion, and to set the immersion time to a period of at least 3 days or more.

[0077] (Test results - Second salt removal confirmation test - Overview) Next, an overview of the second salt removal confirmation test will be explained.

[0078] The second salt removal confirmation test is a test to confirm the state of salt removal of each test specimen according to various test conditions.

[0079] The method of the second salt removal confirmation test is arbitrary, but is as follows: Each test specimen is placed in a container 50 containing water W (fresh water), and each test specimen is immersed at room temperature for 28 days. In addition, the chloride ion concentration of each test specimen is measured at a predetermined timing during the immersion.

[0080] Here, the amount of water W in the container 50 is set to 500 ml for the test specimen B1 described later, 300 ml for the test specimen B2 described later, and 100 ml for the test specimen B3 described later.

[0081] In addition, the test specimens used in the second salt removal confirmation test are divided into test specimens B1 to B3.

[0082] Here, specimens B1 to B3 are tile materials with a width of 108 mm and a length of 60 mm, and are specimens made of tile materials (construction members 20) that have been immersed in acid for a predetermined period of time.

[0083] (Test results - Second salt removal confirmation test - Details of test results) Next, the test results of the second salt removal confirmation test will be described in detail. Fig. 6 is a diagram showing the test results of the second salt removal confirmation test.

[0084] As shown in Figure 6, it was confirmed that the chloride ion concentration of specimens B1 to B3 decreased as the immersion time increased. In particular, it was confirmed that the chloride ion concentration of specimen B1 was more likely to decrease than that of specimens B2 and B3.

[0085] From the above, it was confirmed that it is effective to set the amount of water W in the container 50 to about three times the minimum amount necessary for one construction member 20 to be completely immersed in the water W.

[0086] (Effects of the embodiment) Thus, according to the embodiment, the method includes a removal process in which the construction material 20 is immersed in water W at about 80°C for a predetermined period of time to remove salt from the construction material 20. This makes it possible to more effectively remove salt from the construction material 20 than the conventional technology (technology in which the construction material is immersed in water at room temperature), and to speed up the removal of salt from the construction material 20.

[0087] Furthermore, in the removal process, the water W is replaced multiple times within 72 hours from the start of the removal process, thereby accelerating the removal of salt from the construction material 20 and shortening the time required for the removal process (i.e., the immersion time of the construction material 20).

[0088] Furthermore, since the specified period is at least three days or more, the salt content of the construction material 20 can be reliably removed to below the threshold value, and the time required for the removal process can be shortened while improving the accuracy of the removal process.

[0089] Furthermore, since the construction member 20 is a plate material in which either the width or the length of the construction member 20 is 108 mm or less, and the other of the width or the length of the construction member 20 is 60 mm or less, and the amount of water W in the removal process is 500 ml per one construction member 20, salt removal from the construction member 20 can be effectively performed, and the salt removal from the construction member 20 can be further promoted.

[0090] [III] Modifications to the embodiment Although the embodiments of the present invention have been described above, the specific configurations and means of the present invention can be modified and improved as desired within the scope of the technical ideas of the inventions described in the claims. Such modifications will be described below.

[0091] (About the problem to be solved and the effects of the invention) First, the problems that the invention aims to solve and the effects of the invention are not limited to those described above, and the present invention may solve problems that are not described above or achieve effects that are not described above, or may solve only some of the problems that are described or achieve only some of the effects that are described.

[0092] (shape, number, structure, time series) The components illustrated in the embodiments and drawings may be modified and improved as desired within the scope of the technical concept of the present invention with respect to the shape, numerical values, or structure or chronological relationships of multiple components.

[0093] (About construction materials) In the above embodiment, the construction member 20 is described as having the surface film 22, but this is not limiting, and for example, the surface film 22 may be omitted.

[0094] (How to remove salt) In the above embodiment, the salt removal method for the construction member 20 includes the preparation step, but is not limited to this. For example, when the construction member 20 and the hardened cement body 30 have already been removed from the main body 10 and the hardened cement body 30 has already been removed from the construction member 20, the preparation step may be omitted.

[0095] (Additional Note) The method for removing salt from a construction member in Appendix 1 includes a removing step for removing salt from the construction member after a hardened cement body adhering to the construction member has been removed by acid immersion, the removing step including removing salt from the construction member by immersing the construction member in water having a temperature higher than room temperature and lower than the boiling point for a predetermined period of time.

[0096] The method for removing salt from construction materials of Appendix 2 is the method for removing salt from construction materials of Appendix 1, wherein in the removing step, the water is replaced multiple times within 72 hours from the start of the removing step.

[0097] The method for removing salt from construction materials in Appendix 3 is the method for removing salt from construction materials described in Appendix 2, wherein the temperature of the water is approximately 80°C to 95°C, and the specified period is at least three days or more.

[0098] The method for removing salt from construction materials in Appendix 4 is a method for removing salt from construction materials described in any one of Appendixes 1 to 3, in which the amount of water in the removal step is approximately three times the minimum amount required for one piece of the construction material to be completely immersed in the water.

[0099] (Effect of supplementary notes) The method for removing salt from construction materials described in Appendix 1 includes a removal step of removing salt from the construction materials by immersing the construction materials in water that is higher than room temperature and lower than the boiling point for a predetermined period of time. This makes it possible to remove salt from construction materials more effectively and speed up the removal of salt from construction materials compared to the conventional technology (technique of immersing building materials in water at room temperature).

[0100] According to the method for removing salt from construction materials described in Appendix 2, in the removal process, the water is replaced multiple times within 72 hours from the start of the removal process, thereby accelerating the removal of salt from the construction materials and shortening the time required for the removal process (i.e., the immersion time of the construction materials).

[0101] According to the method for removing salt from construction materials described in Appendix 3, the water temperature is approximately 80°C to 95°C, and the specified period is at least three days or more. Therefore, the salt in the construction materials can be removed to below the threshold value within a period of at least three days or more, making it possible to further shorten the time required for the removal process.

[0102] According to the method for removing salt from construction materials described in Appendix 4, the amount of water used in the removal process is about three times the minimum amount required for one construction material to be completely immersed in water, which makes it possible to effectively remove salt from the construction materials and further promotes the removal of salt from the construction materials. [Explanation of symbols]

[0103] 1 skeleton 10 Main body 20 Construction Materials 21 Construction material body 22 Surface film 30 Hardened cement 40 Constant temperature bath 50 containers W water

Claims

1. 1. A method for removing salt from a construction member after a hardened cement body adhering to the construction member has been removed by acid immersion, comprising the steps of: A removal process is included in which the construction members are immersed in water at a temperature higher than room temperature and lower than the boiling point for a predetermined period of time to remove salt from the construction members. Methods for removing salt from construction materials.

2. In the removal step, the water is replaced multiple times within 72 hours from the start of the removal step. The method for removing salt from a construction member according to claim 1.

3. The temperature of the water is about 80° C. to 95° C. The predetermined period is at least three days or more. The method for removing salt from a construction member according to claim 2.

4. The amount of water in the removing step is about three times the minimum amount required for one of the construction members to be completely immersed in the water. A method for removing salt from a construction member according to any one of claims 1 to 3.

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