JP2023019034A - Method for removing hardened cement - Google Patents

Abstract

To provide a method of removing a cement hardened body capable of increasing the reusability of construction materials.SOLUTION: The removal method of a cement hardened body 30 is a method for removing the cement hardened body 30 adhering to a construction material 20 from the construction material 20. The method includes: a drying step of bringing the cement hardened body 30 to an absolutely dry state or a state approximating it by drying the construction material 20 at a drying temperature below the firing temperature of the glaze contained in a surface film 22 of the construction material 20; and a dipping step of dipping the construction material 20 in an acid solution after the drying step.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for removing hardened cement.

Conventionally, as one of the techniques for reusing construction materials removed from outer walls, construction materials to which hardened cement has adhered are dried at a drying temperature lower than the firing temperature of the construction materials, and then the construction materials are immersed in an acid solution. A technique for removing hardened cement by immersion has been proposed (see Patent Document 1, for example).

JP 2016-199458 A

However, in the above conventional technology, as described above, the construction member to which the hardened cement is attached is dried at a drying temperature equal to or lower than the firing temperature of the construction member. If the firing temperature is higher than that of the glaze contained in , the surface film may be discolored by the heat during drying, so there is room for improvement from the viewpoint of reusability of construction materials.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for removing hardened cement that can enhance the reusability of construction members.

In order to solve the above-described problems and achieve the object, the method for removing hardened cement according to claim 1 is a method for removing the hardened cement adhering to a construction member from the construction member. a drying step of drying the construction member at a drying temperature lower than the firing temperature of the glaze contained in the surface film of the construction member to bring the hardened cement body to an absolute dry state or a state approximating it; and a dipping step of dipping the construction member in an acid solution after the step.

The method for removing hardened cement according to claim 2 is characterized in that, in the method for removing hardened cement according to claim 1, in the drying step, the construction member is dried at the drying temperature of 100° C. to less than 500° C. do.

The method for removing hardened cement according to claim 3 is characterized in that, in the method for removing hardened cement according to claim 2, in the drying step, the construction member is dried at the drying temperature of about 100° C. for at least 3 hours or more. dry.

The method for removing hardened cement bodies according to claim 4 is the method for removing hardened cement bodies according to any one of claims 1 to 3, wherein in the immersion step, the construction member is heated to 50°C to 90°C. It is immersed in the acid solution of about.

The method for removing the hardened cement body according to claim 5 is the method for removing the hardened cement body according to any one of claims 1 to 4, wherein after the drying step and before the immersion step, and a pre-soaking step of immersing the construction member in the acid solution at room temperature.

According to the method for removing the hardened cement body according to claim 1, the hardened cement body is dried in an absolute dry state or Since it includes a drying process that approximates the state, and an immersion process of immersing the construction member in an acid solution after the drying process, the conventional technology (drying the construction member at a drying temperature lower than the sintering temperature of the construction member) Compared to the technique of immersing the cement in an acid solution after being soaked in an acid solution), it is possible to effectively remove the hardened cement from the construction material while suppressing discoloration of the surface film of the construction material, thereby enhancing the reusability of the construction material.

According to the method for removing hardened cement according to claim 2, in the drying step, the construction member is dried at a drying temperature of 100° C. to less than 500° C., so that discoloration of the surface film of the construction member is ensured. can be avoided, and the reusability of construction members can be further enhanced.

According to the method for removing hardened cement according to claim 3, in the drying step, the construction member is dried at a drying temperature of about 100° C. for at least 3 hours or more, so discoloration of the surface film of the construction member does not occur. While reliably avoiding this, the state of the cement hardened body can be reliably brought to the absolute dry state or its approximate state.

According to the method for removing hardened cement according to claim 4, in the immersion step, the construction member is immersed in an acid solution at a temperature of about 50° C. to 90° C. Therefore, the hardened cement is effectively removed while being immersed. The process can be shortened.

According to the method for removing hardened cement according to claim 5, after the drying step and before the immersion step, the pre-immersion step of immersing the construction member in an acid solution at room temperature is further included. , the removal of the hardened cement can be accelerated, and the immersion process can be further shortened.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram conceptually showing a building frame 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. It is a figure which shows the preparation process of the removal method of a cement hardening body. It is a figure which shows the drying process of the removal method of a cement hardening body. FIG. 4 is a diagram showing a pre-immersion step of the method for removing hardened cement. FIG. 2 is a diagram showing an immersion process of a method for removing hardened cement, in which (a) is a diagram showing a state in which a construction member is immersed in an acid solution, and (b) is a diagram showing a state in which the construction member is being scrubbed. is. It is a figure which shows the test result of a 1st removal confirmation test. It is a figure which shows the test result of a discoloration confirmation test. It is a figure which shows the test result of a drying confirmation test. It is a figure which shows the test result of a 2nd removal confirmation test. FIG. 3 is a diagram showing the test results of the third removal confirmation test, where (a) is a diagram showing the relationship between the temperature of the second acid solution and the amount of mass reduction of each specimen, and (b) is the temperature of the second acid solution and It is a figure which shows the relationship with the titration concentration of a 2nd acid solution. It is a figure which shows the test result of a 4th removal confirmation test.

An embodiment of the method for removing hardened cement according to the present invention will be described in detail below with reference to the accompanying drawings. First, [I] the basic concept of the embodiment will be described, then [II] the specific contents of the embodiment will be described, and finally [III] modifications of the embodiment will be described. However, the present invention is not limited by the embodiment.

[I] Basic concept of the embodiment First, the basic concept of the embodiment will be described. Embodiments generally relate to a removal method for removing hardened cement adhering to a construction member from the construction member.

Here, the specific structure and type of "construction member" is arbitrary, but for example, exterior materials (for example, tile-based exterior materials, brick-based exterior materials, stone-based exterior materials) and interior materials (as examples, tile-based interior materials, brick-based interior materials, stone-based exterior materials), etc., but implementation In the form of , a tile-based exterior material for walls will be described.

In addition, although the specific structure and type of "structure" are arbitrary, for example, building structures such as office buildings, commercial facilities, public facilities, and collective housing such as apartments and condominiums, tunnels, dams, etc. Although the concept includes civil engineering structures, the embodiment will be described as an office building.

In addition, the term "hardened cement" is used for attaching a construction member to the main body of the skeleton, which will be described later. The embodiment will be described as including a base material and an attachment material made of mortar.

In addition, the construction member from which the hardened cement has been removed by this removal method may be used for any specific purpose, but for example, it may Reuse as an interior material, and use for purposes other than exterior or interior materials (for example, fence materials for flower beds, etc.) fall under this category.

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

(composition)
First, the configuration of the skeleton of a structure (specifically, an office building) including construction members to which the method for removing hardened cement according to the embodiment is applied will be described.

1A and 1B are diagrams conceptually showing a building frame 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.

In the following explanation, the X direction in FIG. The forward direction, the -Y direction is the rearward direction of the frame), and the Z direction in FIG.

A skeleton 1 is a wall (for example, an outer wall) that constitutes a structure, and includes a skeleton main body 10, a construction member 20, and a hardened cement 30, as shown in FIG.

(Construction - frame body)
The skeleton body 10 is the basic structure of the skeleton 1 . The frame main body 10 is formed of a long rectangular plate-like body made of concrete (for example, made of reinforced concrete or prestressed concrete), and as shown in FIG. It is provided so as to follow and is fixed to an installation target (for example, a floor or the like) (not shown).

(Construction-Construction member)
The construction member 20 is configured using, for example, a known tile-based exterior material or the like, and as shown in FIG. ) and comprises a construction member body 21 and a surface film 22 .

(Construction-Construction member-Construction member body)
The construction member body 21 is the basic structure of the construction member 20 . The construction member main body 21 is made of, for example, a known tile material (for example, a rectangular tile material having a tile portion and a joint portion) or the like, and as shown in FIG. A plurality of them are arranged substantially along the left-right direction so as to cover them, and a plurality of them are arranged substantially along the up-down direction.

Further, the specific configuration of the construction member main body 21 is configured as follows in the embodiment.

That is, as shown in FIG. 1, the entire outer surface of the construction member body 21 (in FIG. 1, the entire front surface) is formed flat. However, it is not limited to this, and may be formed in a non-flat shape, for example. In addition, the entire inner surface of the construction member body 21 (the entire rear surface in FIG. 1) is formed in a non-flat shape, and more specifically, it is formed to have a plurality of rearward projecting protrusions. ing.

(Construction-Construction member-Surface film)
The surface film 22 is a film coated with glaze. This surface film 22 is provided on the entire outer surface of the construction member body 21 as shown in FIG. It is formed by applying and baking the entire surface.

Here, the “glaze” means a chemical used to enhance the decorativeness and strength of the construction member ₂₀ and prevent the construction member 20 from being soiled. (e.g., SiO ₂ component, etc.), R ₂ O ₃ component (e.g., Al ₂ O ₃ component, etc.) forming a joint with the construction member body 21 and a part of the skeleton of the glaze, partly destroying the skeleton of the glaze, and It is a chemical composed of RO components (CaO component, MgO component) and R ₂ O components (Na ₂ O component, K ₂ O component, etc.) that lower the melting temperature.

In addition, the specific type of "glaze" is arbitrary. "Crystal glaze" containing crystals and "milky white glaze" with multiple non-crystalline phases fall into this category.

Further, the various glazes described above are roughly classified into low-fired glazes and high-fired glazes. Among these, the “low-temperature glaze” is a glaze that is fired at a relatively low temperature (for example, firing temperature of about 750° C. to 1100° C.), and includes alkaline glaze, luster glaze, and the like. In addition, "high-temperature glaze" is a glaze whose firing temperature is higher than that of low-temperature glaze (for example, about 1100°C to 1300°C firing temperature). Examples include lime glaze and ash glaze. .

The amount of glaze to be applied is arbitrary, but it is desirable to set it as small as possible from the viewpoint of forming a uniform surface film 22, but it may vary depending on the type of glaze, the type of the construction member main body 21, etc. Therefore, for example, it may be set based on experimental results, analysis results, or the like.

(Composition - hardened cement)
The hardened cement 30 is for attaching the construction member 20 to the building body 10 . The hardened cement 30 is provided between the building frame body 10 and the construction member body 21, as shown in FIG. 1(b).

The hardened cement body 30 may have any specific configuration, but in the embodiment, as shown in FIG.

Among these, the base portion 31 is for correcting the unevenness of the skeleton body 10 . The base portion 31 is made of, for example, a known mortar base material, and is provided so as to substantially cover the entire outer surface of the skeleton body 10, as shown in FIG. 1(b).

Further, the sticking portion 32 is for sticking the construction member 20 to the base material. The sticking portion 32 is made of, for example, a known mortar sticking material or the like, and is provided so as to substantially cover the entire outer surface of the base portion 31 as shown in FIG. 1(b).

(Method for removing hardened cement)
Next, a method for removing the hardened cement 30 according to the embodiment will be described.

FIG. 2 is a diagram showing a preparatory process for removing the cement hardened body 30. As shown in FIG. FIG. 3 is a diagram showing the drying process of the method for removing the hardened cement 30. As shown in FIG. FIG. 4 is a diagram showing the pre-immersion step of the method for removing the hardened cement 30. As shown in FIG. 5A and 5B are diagrams showing the immersion process of the method for removing the hardened cement 30. FIG. 5A shows a state in which the construction member 20 is immersed in an acid solution, and FIG. It is a figure which shows the state which is doing.

The method for removing the hardened cement 30 according to the embodiment is a method for removing the hardened cement 30 adhering to the construction member 20 from the construction member 20. As shown in FIGS. It includes a preparation step, a drying step, a pre-soaking step, and a soaking step.

(Method for removing hardened cement - preparation step)
Returning to FIG. 2, first, the preparation process will be described.

The preparation process is a process for preparing to remove the hardened cement 30 from the construction member 20 .

Specifically, first, as shown in FIG. 2, a known cutting tool (not shown) is used to cut a part of the construction member 20 together with the hardened cement 30, and then a known peeling tool (not shown) is cut. is used to separate the cut construction member 20 and the hardened cement 30 from the building body 10 . In this case, for example, in order to enhance the reusability of the construction member 20, the construction member 20 is cut so that at least one tile portion of the construction member body 21 is included in the cut area of the construction member 20, and the construction member body 21 is cut. It is desirable to cut the joint portion of the construction member body 21 without cutting the tile portion.

(Method for removing hardened cement - drying step)
Next, the drying process will be explained.

In the drying step, after the preparation step, the construction member 20 is dried at a drying temperature lower than the firing temperature of the glaze contained in the surface film 22 of the construction member 20, thereby bringing the hardened cement 30 to an absolute dry state or a state approximating it. It is a process to make

Here, the reason why the construction member 20 is dried to the absolute dry state or its approximate state is that the moisture inside the hardened cement 30 adhering to the construction member 20 is removed by the drying. This is for facilitating permeation of the first acid solution AL1 or the second acid solution AL2 described later into the hardened cement body 30 . Note that the "absolutely dry state or its approximate state" corresponds to, for example, a state in which the water content of the construction member 20 is approximately 5% or less.

The reason why the construction member 20 is dried at a drying temperature lower than the firing temperature of the glaze included in the surface film 22 is that drying the construction member 20 at a drying temperature exceeding the firing temperature of the glaze included in the surface film 22 causes the drying. This is to avoid such a problem because the surface film 22 may be discolored (for example, whitened) due to re-melting of the glaze due to the heat of the time.

As for the details of the drying process, as shown in FIG. (specifically, a drying temperature lower than the firing temperature of the construction member 20) for a predetermined time.

Although the specific method for setting the drying temperature is arbitrary, in the embodiment, even with various types of glazes, the surface film 22 does not discolor and the cement hardened body 30 can be effectively dried. For drying, the temperature is set to about 100° C. to 700° C. based on the test results of the first removal confirmation test and discoloration confirmation test, which will be described later.

However, if the drying temperature is close to the firing temperature of the glaze (for example, the drying temperature = 700 ° C., the firing temperature of the glaze (specifically, the low-temperature glaze) = 750 ° C. ), discoloration of the surface film 22 of the construction member 20 may occur. Therefore, in order to reliably avoid discoloration of the surface film 22, it is more preferable to set the temperature from 100° C. to less than 500° C. based on the test results of the discoloration confirmation test described later.

The specific method for setting the predetermined time is arbitrary. good. As a result, the state of the hardened cement 30 can be reliably brought to an absolutely dry state or a state approximating it while reliably avoiding discoloration of the surface film 22 of the construction member 20 . However, not limited to this, for example, when the construction member 20 is dried at a drying temperature of 100° C. or higher, it may be dried for 3 hours or longer, or may be dried for less than 3 hours.

Such a drying process makes it possible to bring the hardened cement body 30 into an absolutely dry state or a state similar thereto while avoiding discoloration of the surface film 22 .

(Method for removing hardened cement - pre-immersion step)
Next, the pre-immersion step will be described.

The pre-soaking process is a process of immersing the construction member 20 in an acid solution AL1 at room temperature (hereinafter referred to as "first acid solution AL1") after the drying process and before the immersing process.

Here, the reason why the pre-soaking step is performed is that the hardened cement body 30 attached to the construction member 20 is impregnated with the first acid solution AL1 so that the hardened cement body 30 is exposed to the second acid solution, which will be described later. This is to shorten the permeation time of AL2.

In addition, as shown in FIG. 4, the details of the processing contents of the pre-immersion process are as follows: the construction member 20 dried in the drying process is put into the first container 42 containing the first acid solution AL1 at normal temperature. , the construction member 20 is immersed in the first acid solution AL1 for about 20 hours (or less than 20 hours or more than 20 hours).

In addition, the amount of the first acid solution AL1 contained in the first container 42 is arbitrary as long as the entire hardened cement body 30 can be immersed. The amount may be set so that both the hardened cement 20 and the hardened cement 30 are completely immersed. However, the present invention is not limited to this. For example, although the hardened cement body 30 is completely immersed, the amount may be set such that a part of the construction member 20 is not immersed in the first acid solution AL1 (the second Substantially the same applies to the capacity of the second acid solution AL2 in the container 52).

Further, the type of acid contained in the first acid solution AL1 is arbitrary as long as it can react with at least a part of the components of the hardened cement 30 to dissolve the hardened cement 30. For example, hydrochloric acid , nitric acid, sulfuric acid, citric acid, hydroiodic acid, perchloric acid, hydrobromic acid, chloric acid, bromic acid, iodic acid, perbromic acid, metaperiodic acid, permanganic acid, thiocyanic acid, aqua regia, Malic acid, lactic acid, glycolic acid, oxalic acid, malonic acid, succinic acid, phthalic acid, acetic acid, formic acid, tartaric acid, benzoic acid, propionic acid, butyric acid, valeric acid, etc. can be used (the second acid described later) The same applies to the type of acid contained in the solution AL2).

Also, the method of setting the acid concentration of the first acid solution AL1 is arbitrary, but in the embodiment, it is set to the same concentration as the acid concentration of the second acid solution AL2, which will be described later. However, not limited to this, for example, it may be set to a concentration lower than the acid concentration of the second acid solution AL2 described later, or set to a concentration higher than the acid concentration of the second acid solution AL2 described later. good too.

Such a pre-soaking process can accelerate the removal of the hardened cement 30 in the immersing process, and shorten the immersing process.

(Method for removing hardened cement - immersion step)
Next, the immersion process will be described.

The immersion process is a process of immersing the construction member 20 in an acid solution AL2 (hereinafter referred to as "second acid solution AL2") after the drying process and the pre-immersion process.

Specifically, in order to effectively remove the hardened cement 30, the construction member 20 pre-soaked in the pre-soaking step is immersed in the second acid solution AL2 at a predetermined temperature for a predetermined period of time, and then removed by a predetermined removal method. The removal of the hardened cement body 30 from the construction member 20 is repeated multiple times.

More specifically, as shown in FIG. 5(a), the second acid solution AL2 heated to about 50° C. to 90° C. by a known heating device 51 (for example, a gas-type heating device) was accommodated. The construction member 20 is put into the second container 52 and immersed in the second acid solution AL2 for about 15 minutes. After that, as shown in FIG. 5B, using a known brush 53 or the like, the immersed construction member 20 is scrubbed in a third container 54 containing water W (for example, fresh water). removes the dissolved hardened cement body 30 from the construction member 20. As shown in FIG. Then, based on the test results of the fourth removal confirmation test described later, these series of operations are repeated four times (that is, while the construction member 20 is scrubbed, the construction member 20 is soaked in the second acid solution AL2 for a total of 60 minutes. immersion).

However, without being limited to this, for example, the above series of operations may be performed five times or more. Alternatively, the construction member 20 is immersed in the second acid solution AL2 for a period exceeding 15 minutes (or less than 15 minutes) until the hardened cement body 30 is completely removed, and then the construction member 20 is scrubbed. may be repeated several times. Alternatively, the scrubbing of the construction member 20 may be omitted and the construction member 20 may simply be immersed in the second acid solution AL2 for 60 minutes (or longer than 60 minutes).

Here, the reason for setting the temperature of the second acid solution AL2 to about 50° C. to 90° C. is as follows. That is, as shown in the test results of the third removal confirmation test described later, when the temperature of the second acid solution AL2 is set to the boiling point or a temperature in the vicinity thereof, the second acid solution AL2 decreases as the immersion period elapses. There is a possibility that the acid concentration of the second acid solution AL2 cannot be maintained due to the decrease in the acid concentration (specifically, the titration concentration of the acid). In addition, when the temperature of the second acid solution AL2 is set to less than 50 ° C., the effect of removing the hardened cement 30 is lower than when the temperature of the second acid solution AL2 is set to 50 ° C. or higher. It may become difficult to shorten the process. Therefore, this is to effectively remove the hardened cement 30 while avoiding these problems.

Also, the method for setting the acid concentration of the second acid solution AL2 is arbitrary, but in the embodiment, based on the test results of the second removal confirmation test and the third removal confirmation test described later, 3% by weight to 35% by weight It is set to approximately 35% by weight, and more specifically, it is preferably set to approximately 35% by weight in order to effectively remove the hardened cement 30 .

In addition, the above-described predetermined removal method has been described as scrubbing the construction member 20 as described above, but is not limited to this, for example, applying hot air to the construction member 20, or or a combination thereof.

Such an immersion process can effectively remove the hardened cement 30 .

By the removal method as described above, the hardened cement 30 can be removed from the construction member 20 in comparison with the conventional technology (a technique in which the construction member is dried at a drying temperature equal to or lower than the firing temperature of the construction member and then immersed in an acid solution). While removing effectively, discoloration of the surface film 22 of the construction member 20 can be suppressed, and the reusability of the construction member 20 can be enhanced.

(Test results)
Next, the results of various tests conducted by the applicant will be described. Here, the first removal confirmation test to the fourth removal confirmation test, the discoloration confirmation test, and the drying confirmation test will be described.

(Test results-first removal confirmation test-overview)
Next, an outline of the first removal confirmation test will be described.

The first removal confirmation test is a test for confirming the removal amount of the hardened cement 30 in each test specimen under various test conditions (specifically, conditions with or without a drying process).

Although the test method for this first removal confirmation test is arbitrary, it is as follows. That is, first, the mass of each specimen is measured using a known mass measuring instrument. Next, a drying step (specifically, the drying device 41 is used to dry the test body A2, which will be described later, at about 100° C. for about 3 hours) is performed only on the test body A2, which will be described later. In addition, each specimen is placed in the corresponding second container 52 containing the second acid solution AL2 having an acid concentration of 35% by weight and a temperature of 80° C., and the specimen is immersed for about 15 minutes. After the immersion, the mass of each specimen is measured again using the mass measuring instrument, and the mass reduction amount indicating the difference in mass before and after the immersion is calculated.

Also, the specimens used in the first removal confirmation test are divided into specimens A1 and A2. Here, the specimen A1 and the specimen A2 are: construction member 20 = tile material having a planar shape of 45 mm x 45 mm; This is a test piece made of a mortar substrate having a thickness of about 20 mm.

(Test results-first removal confirmation test-details of test results)
Next, the details of the test results of the first removal confirmation test will be described. FIG. 6 is a diagram showing test results of the first removal confirmation test.

As shown in FIG. 6, it was confirmed that the mass reduction amount of the specimen A2 was larger than that of the specimen A1. In particular, regarding the mass reduction amount of the specimen A2, although the immersion time of the second acid solution AL2 in the specimen A2 was shorter than the immersion time of the second acid solution AL2 in the specimen A1, the mass of the specimen A1 was It was confirmed that it was about four times the amount of decrease.

From the above, the effectiveness of performing the drying process has been confirmed.

(Test results-Discoloration confirmation test-Summary)
Next, an outline of the discoloration confirmation test will be described.

The discoloration confirmation test is a test for confirming the presence or absence of discoloration of each specimen when dried at various drying temperatures.

Although the test method for this discoloration confirmation test is arbitrary, it is as follows. That is, first, using the drying device 41 (the drying device 41 having a temperature rising gradient of 2.5 to 3.0° C./min), each specimen is dried at a predetermined drying temperature for a predetermined time. Specifically, the specimens B1 and B3 were dried at about 450°C for 180 minutes after reaching the target temperature, and the specimens B4 and B6 were dried at about 700°C for 180 minutes after reaching the target temperature. After drying, the specimens B7 and B9 are dried at about 900° C. for 120 minutes after reaching the target temperature. After drying each specimen, the specimen is naturally cooled inside the drying device 41 .

Also, the specimens used in the discoloration confirmation test are divided into specimens B1 to B9. Here, the specimens B1 to B9 are floor tile materials installed in a building. In addition, the color of the test body B1, the test body B4, and the test body B7 is red, the color of the test body B2, the test body B5, and the test body B8 is blue, and the test body B3, the test body B6, and the test body The color of body B9 is beige.

(Test results-Discoloration confirmation test-Details of test results)
Next, the details of the test results of the discoloration confirmation test will be described. FIG. 7 is a diagram showing test results of a discoloration confirmation test.

As shown in FIG. 7, no discoloration was observed on the surface film 22 of the specimens B1 to B6, but discoloration of the surface film 22 (specifically, whitening of the surface film 22) was confirmed.

From the above, the effectiveness of drying the construction member 20 at a drying temperature lower than the firing temperature of the glaze contained in the surface film 22 of the construction member 20 has been confirmed.

(Test results-drying confirmation test-overview)
Next, an outline of the drying confirmation test will be described.

The dry confirmation test is a test for confirming the dry state of the specimen.

Although the test method for this drying confirmation test is arbitrary, it is as follows. That is, first, the mass of the specimen is measured using a known mass measuring instrument. Next, the test body is dried at about 100° C. using the drying device 41 . Then, during the drying, every time a predetermined time passes (specifically, every 0.5 hours, 1 hour, 2 hours, 3 hours, and 24 hours), using a known mass measuring instrument, By measuring the mass of the specimen, the moisture content is calculated for each predetermined time.

Moreover, the specimen used in the drying confirmation test is a specimen having substantially the same structure as the specimen A1.

(Test results - Drying confirmation test - Details of test results)
Next, the details of the test results of the drying confirmation test will be described. FIG. 8 is a diagram showing test results of a drying confirmation test.

As shown in FIG. 8, when the drying time was less than 3 hours, the moisture content of the specimen was 5% or more, but when the drying time was 3 hours or more, the moisture content of the specimen was was confirmed to be less than 5%.

From the above, the effectiveness of drying the construction member 20 at a drying temperature of about 100° C. for at least 3 hours or more has been confirmed.

(Test results-Second removal confirmation test-Overview)
Next, an outline of the second removal confirmation test will be described.

The second removal confirmation test is a test for confirming the removal amount of the hardened cement 30 in each test specimen under various test conditions (specifically, the temperature condition and the acid concentration condition of the second acid solution AL2). be.

Although the test method for this second removal confirmation test is arbitrary, it is as follows. That is, first, the mass of each specimen is measured using a known mass measuring instrument. Next, each specimen is put into the corresponding second container 52 containing the second acid solution AL2 (specifically, an acid solution containing hydrochloric acid), and the specimen is immersed for a predetermined period of time. Then, during and after the immersion, the mass of each specimen is measured using a mass measuring instrument.

Here, the temperature of the second acid solution AL2 is set to room temperature for the specimens C1 and C2, which will be described later, and to 80° C. for the specimen C3, which will be described later.

The acid concentration of the second acid solution AL2 is set to about 3% by weight (1 mol/L) for the specimen C1 described later, and about 35% by weight for the specimens C2 and C3 described later. (11.38 mol/L).

Also, the specimens used in the second removal confirmation test are divided into specimens C1 to C3. Here, the test bodies C1 to C3 are test bodies configured substantially the same as the test body A1.

(Test results-Second removal confirmation test-Details of test results)
Next, the details of the test results of the second removal confirmation test will be described. FIG. 9 is a diagram showing test results of the second removal confirmation test.

As shown in FIG. 9, it was confirmed that the masses of the specimens C1 to C3 decreased as the immersion period passed. Moreover, it was confirmed that the mass of the specimens C2 and C3 decreased in a shorter immersion period than that of the specimen C1. In particular, it was confirmed that the dissolution amount until the mortar mass of the specimen C3 reached about 85% was about 72 times the dissolution amount until the mortar mass of the specimen C1 reached about 85%.

From the above, it was possible to confirm the effectiveness of immersing the construction member 20 in the second acid solution AL2 having an acid concentration of about 3% to 35% by weight and a temperature of about 80°C.

(Test results - 3rd removal confirmation test - overview)
Next, an outline of the third removal confirmation test will be described.

The third removal confirmation test is a test for confirming the removal amount of the hardened cement 30 in each test specimen under various test conditions (specifically, the temperature condition and the acid concentration condition of the second acid solution AL2). be.

Although the test method for this third removal confirmation test is arbitrary, it is as follows. That is, first, the mass of each specimen is measured using a known mass measuring instrument. Next, each specimen is put into the corresponding second container 52 containing the second acid solution AL2, and the specimen is immersed for 60 minutes. Then, after the immersion, the mass of each specimen is measured again using the mass measuring instrument, and the mass decrease amount indicating the difference in mass before and after the immersion is calculated. Measure the titer of the second acid solution AL2 in.

Here, the temperature of the second acid solution AL2 is set to the boiling point temperature of the second acid solution AL2 for specimens D1 to D3, which will be described later. C., set to 50.degree. C. for specimens F1 to F3 described later, and set to 20.degree. C. for specimens G1 to G3 to be described later.

Further, the acid concentration of the second acid solution AL2 is set to 8.75% by weight for specimens D1, E1, F1, and G1, which will be described later. Specimens E2, F2, and G2 are set to 20% by weight, and specimens D3, E3, F3, and G3, which will be described later, are set to 35% by weight.

The specimens used in the third removal confirmation test are divided into specimens D1 to D3, specimens E1 to E3, specimens F1 to F3, and specimens G1 to G3. . Here, specimen D1 to specimen D3, specimen E1 to specimen E3, specimen F1 to specimen F3, and specimen G1 to specimen G3 are construction members 20 = tiles having a planar shape of 45 mm x 45 mm Hardened cement 30 adhering to the material and construction member 20 = a test piece made of mortar with a thickness of about 20 mm.

(Test results-third removal confirmation test-details of test results)
Next, details of the test results of the third removal confirmation test will be described. FIG. 10 is a diagram showing the test results of the third removal confirmation test, (a) is a diagram showing the relationship between the temperature of the second acid solution AL2 and the amount of mass reduction of each specimen, and (b) is the second It is a figure which shows the relationship between the temperature of acid solution AL2, and the titration concentration of 2nd acid solution AL2.

As shown in FIG. 10(a), the amount of mass reduction from the specimen D1 to the specimen D3, the amount of mass reduction from the specimen E1 to the specimen E2, and from the specimen F1 to the specimen F2 are as follows: It was confirmed that the amount of mass reduction was greater than that of the specimens G1 to G3. Considering the amount of mass reduction from the specimen D1 to the specimen D3, the amount of weight reduction from the specimen E1 to the specimen E2, and from the specimen F1 to the specimen F2, the temperature of the second acid solution AL2 is 50°C to 90°C. If it is about the extent, it is estimated that the amount of mass reduction will be 15 g or more.

Further, as shown in FIG. 10(b), the titration concentration of the second acid solution AL2 of the specimen D1, the specimen E1, the specimen F1, and the specimen G1 is 8.75% by weight, which is the original concentration. It is confirmed that the titration concentration of the second acid solution AL2 of the specimen D2, specimen E2, specimen F2, and specimen G2 is almost the same as the original concentration of 25% by weight. was done. On the other hand, the titer concentration of the second acid solution AL2 of the specimen E3, the specimen F3, and the specimen G3 was almost the same as the original concentration of 35% by weight, but the titer concentration of the specimen D3 was is significantly lower than 35% by weight due to the evaporation of the components of the second acid solution AL2.

From the above, the effectiveness of immersing the construction member 20 in the second acid solution AL2 having an acid concentration of 8 wt % to 35 wt % and a temperature of about 50° C. to 90° C. has been confirmed.

(Test results-4th removal confirmation test-overview)
Next, an outline of the fourth removal confirmation test will be described.

In the fourth removal confirmation test, the removal amount of the hardened cement 30 in each test piece is confirmed under various test conditions (specifically, the condition of the immersion period and the condition of the presence or absence of the removal work of the hardened cement 30). It is a test for

Although the test method of the fourth removal confirmation test is arbitrary, it is as follows. That is, first, the mass of each specimen is measured using a known mass measuring instrument. Next, each specimen was put into a corresponding second container 52 containing a second acid solution AL2 (specifically, an acid solution containing hydrochloric acid) having an acid concentration of 35% by weight and a temperature of 80°C. , the test piece is immersed for a predetermined period (for the test piece H3, which will be described later, the test piece H3, which will be described later, is rubbed four times during and after the immersion). After the immersion, the mass of each specimen is measured again using the mass measuring instrument, and the mass reduction amount indicating the difference in mass before and after the immersion is calculated.

Here, the immersion period of the second acid solution AL2 was set to 15 minutes for the specimen H1 to be described later, set to 60 minutes for the specimen H2 to be described later, and set 15 minutes×15 minutes for the specimen H3 to be described later. Set to 4 times (ie soak for 60 minutes total).

Also, the specimens used in the fourth removal confirmation test are divided into specimens H1 to H3. Here, the test bodies H1 to H3 are test bodies configured substantially the same as the test body D1.

(Test results-4th removal confirmation test-details of test results)
Next, the details of the test results of the fourth removal confirmation test will be described. FIG. 11 is a diagram showing test results of the fourth removal confirmation test.

As shown in FIG. 11, it was confirmed that the mass reduction amount of the specimen H3 was larger than that of the specimens H1 and H2. Specifically, it was confirmed that the mass reduction amount of the specimen H3 was about 1.5 times the mass reduction amount of the specimen H2.

From the above, it is possible to confirm the effectiveness of removing the hardened cement 30 from the construction member 20 by a predetermined removal method multiple times after the construction member 20 is immersed in the second acid solution AL2 for about 15 minutes. rice field.

(Effect of Embodiment)
As described above, according to the embodiment, by drying the construction member 20 at a drying temperature lower than the firing temperature of the glaze contained in the surface film 22 of the construction member 20, the cement hardened body 30 is kept in an absolutely dry state or an approximation thereof. and the step of immersing the construction member 20 in an acid solution after the drying step. The hardened cement 30 can be effectively removed from the construction member 20, while suppressing the discoloration of the surface film 22 of the construction member 20, thereby enhancing the reusability of the construction member 20. be able to.

In addition, in the drying process, the construction member 20 is dried at a drying temperature of 100° C. to less than 500° C., so discoloration of the surface film 22 of the construction member 20 can be reliably avoided, and the construction member 20 can be reused. can be further enhanced.

In the drying process, the construction member 20 is dried at a drying temperature of about 100° C. for at least 3 hours or more, so that the hardened cement 30 is dried while reliably avoiding discoloration of the surface film 22 of the construction member 20 . The condition can be ensured to be absolute dry condition or its approximation.

Further, in the immersion process, the construction member 20 is immersed in an acid solution of about 50° C. to 90° C., so that the hardened cement body 30 can be effectively removed and the immersion process can be shortened.

In addition, after the drying process and before the immersion process, a pre-immersion process of immersing the construction member 20 in an acid solution at room temperature is further included, so that the removal of the hardened cement 30 can be facilitated in the immersion process. , the immersion process can be further shortened.

[III] Modifications to the Embodiments Although the embodiments of the present invention have been described above, specific configurations and means of the present invention are within the scope of the technical ideas of each invention described in the claims. , can be arbitrarily modified and improved. Such modifications will be described below.

(Problem to be solved and effect of invention)
First, the problems to be solved by the invention and the effects of the invention are not limited to the above-described contents, and the present invention solves problems not described above or achieves effects not described above. and may solve only part of the problems described or provide only part of the advantages described.

(Regarding shapes, numbers, structures, and time series)
With respect to the components illustrated in the embodiments and drawings, the shape, numerical value, structure of multiple components, or time-series interrelationships may be arbitrarily modified and improved within the scope of the technical idea of the present invention. can be done.

(About acid concentration of acid solution)
In the above embodiment, it was explained that the acid concentration of the acid solution (specifically, the first acid solution AL1 and the second acid solution AL2) was set to about 3% by weight to 35% by weight. Not exclusively. For example, if it is acceptable that the period required for removing the hardened cement 30 is longer than in the above embodiment, the content may be set to less than 3% by weight. Alternatively, the concentration may be set above 35% by weight.

(Method for removing hardened cement)
In the above embodiment, the method for removing the hardened cement 30 includes the preparation step and the pre-immersion step, but the method is not limited to this. For example, if the construction member 20 and the hardened cement 30 have already been removed from the building body 10, the preparation process may be omitted. Alternatively, if the hardened cement 30 is made of a material that is easily removed from the construction member 20, the pre-soaking step may be omitted.

Further, in the above embodiment, the construction member 20 is dried at a drying temperature of about 100° C. to 700° C. in the drying step, but the drying process is not limited to this. For example, the construction member 20 may be dried at a drying temperature of less than 100°C, and as an example, may be dried at a drying temperature on the order of 50°C to 90°C.

Further, in the above embodiment, the construction member 20 is immersed in the acid solution at about 50° C. to 90° C. in the immersion step, but the present invention is not limited to this. For example, the construction member 20 may be immersed in an acid solution below 50° C., and as an example, may be immersed in an acid solution at room temperature.

(Appendix)
The method for removing hardened cement described in Supplementary Note 1 is a method for removing the hardened cement adhering to a construction member from the construction member, wherein the temperature is lower than the firing temperature of the glaze contained in the surface film of the construction member. a drying step of drying the construction member at a drying temperature of to bring the hardened cement body to an absolute dry state or a state approximating it, and a immersion step of immersing the construction member in an acid solution after the drying step; including.

The method for removing hardened cement according to Appendix 2 is the method for removing hardened cement according to Appendix 1, wherein in the drying step, the construction member is dried at the drying temperature of 100°C to less than 500°C.

The method for removing hardened cement according to Appendix 3 is the method for removing hardened cement according to Appendix 2, wherein in the drying step, the construction member is dried at the drying temperature of about 100° C. for at least 3 hours.

The method for removing hardened cement according to Appendix 4 is the method for removing hardened cement according to any one of Appendixes 1 to 3, wherein in the dipping step, the construction member is treated with the acid of about 50°C to 90°C. Immerse in solution.

The method for removing hardened cement according to Supplementary Note 5 is the method for removing hardened cement according to any one of Supplements 1 to 4, wherein the construction member is removed after the drying step and before the immersion step. is immersed in the acid solution at normal temperature.

(Effect of Supplementary Note)
According to the method for removing hardened cement described in Supplementary Note 1, by drying the construction member at a drying temperature lower than the firing temperature of the glaze contained in the surface film of the construction member, the hardened cement is kept in an absolutely dry state or in an absolutely dry state. Since it includes a drying step to approximate the state, and an immersion step of immersing the construction member in an acid solution after the drying step, the conventional technology (the construction member is dried at a drying temperature equal to or lower than the sintering temperature of the construction member Compared to the technique of immersing the cement in an acid solution), it is possible to effectively remove the hardened cement from the construction material while suppressing discoloration of the surface film of the construction material, thereby enhancing the reusability of the construction material.

According to the method for removing hardened cement described in appendix 2, in the drying step, the construction member is dried at a drying temperature of 100° C. to less than 500° C., so that discoloration of the surface film of the construction member is ensured. can be avoided, and the reusability of construction members can be further enhanced.

According to the method for removing hardened cement described in Supplementary Note 3, in the drying step, the construction member is dried at a drying temperature of about 100° C. for at least 3 hours or more, so discoloration of the surface film of the construction member is ensured. It is possible to ensure that the state of the hardened cement body is in the absolutely dry state or its approximation state while avoiding the

According to the method for removing hardened cement described in appendix 4, in the immersion step, the construction member is immersed in the acid solution at about 50° C. to 90° C., so that the hardened cement is effectively removed while the immersion step is performed. can be shortened.

According to the method for removing hardened cement described in appendix 5, after the drying step and before the immersion step, the pre-immersion step of immersing the construction member in an acid solution at room temperature is further included. Removal of the hardened cement can be accelerated, and the immersion process can be further shortened.

1 frame 10 frame body 20 construction member 21 construction member body 22 surface film 30 hardened cement 31 base portion 32 sticking portion 41 drying device 42 first container 51 heating device 52 second container 53 brush 54 third container AL1 first acid solution AL2 Second acid solution W Water

Claims (5)

A removal method for removing hardened cement adhering to a construction member from the construction member, comprising:
a drying step of drying the construction member at a drying temperature lower than the firing temperature of the glaze contained in the surface film of the construction member to bring the hardened cement body to an absolute dry state or a state approximating it;
a dipping step of dipping the construction member in an acid solution after the drying step;
A method for removing hardened cement containing In the drying step, the construction member is dried at the drying temperature of 100° C. to less than 500° C.
The method for removing hardened cement according to claim 1. In the drying step, the construction member is dried at the drying temperature of about 100° C. for at least 3 hours.
The method for removing hardened cement according to claim 2. In the immersion step, the construction member is immersed in the acid solution at about 50°C to 90°C.
The method for removing hardened cement according to any one of claims 1 to 3. further comprising a pre-soaking step of immersing the construction member in an acid solution at room temperature after the drying step and before the immersing step;
The method for removing hardened cement according to any one of claims 1 to 4.

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