Method for measuring depth of neutralization of concrete structure and indication material used for the same

Abstract

To bring an indication material into close adhesion to a concrete hole wall surface in a press-contact state to promote a color reaction of a phenolphthalein agent, thereby improving measurement accuracy.SOLUTION: A method for measuring the depth of neutralization of a concrete structure includes: inserting, into a bore 12, an indication material 1 that is a base material sheet 2 with an elongated shape carrying a phenolphthalein agent-containing layer 3 on its front side; inserting, into a bore space on a rear face of the indication material 1, an elastic tube 6 expandable in a radial direction by a fed fluid; feeding air into the elastic tube 6 to expand the elastic tube 6 in the radial direction, and pressing the indication material 1 against a hole wall surface from the rear face side to bring them into close adhesion in a press-contact state, thereby promoting a color reaction of a phenolphthalein agent; and after the lapse of a predetermined time, removing the fluid from the elastic tube 6 to shrink the elastic tube and drawing out the elastic tube from the bore 12, and pulling out the indication material 1 from the bore 12 and measuring the distance from a concrete opening end corresponding position of the indication material 1 to a coloration region, thereby measuring the depth of neutralization.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for simply and accurately measuring the carbonation depth of a concrete structure and an indicator material therefor.

Background Art

[0002] In concrete structures constructed in the past, carbon dioxide in the atmosphere gradually penetrates into the concrete, and a phenomenon occurs in which the concrete, which is originally strongly alkaline, approaches neutrality. As carbonation progresses from the surface of the concrete, the passive film of the reinforcing bar is destroyed and the corrosion of the reinforcing bar progresses. Therefore, it is necessary to measure and manage the progress of carbonation of the concrete structure.

[0003] Conventionally, as a method for measuring the carbonation depth of concrete, the method specified in JIS A 1152 can be cited. This method is a method for measuring the carbonation depth by spraying a phenolphthalein solution on a cored specimen or a chipped part. However, in this method, a core with a diameter of several tens of centimeters is extracted, and the damage to the main body structure becomes a structural problem. In addition, it is necessary to bring in a boring device and use a large amount of water, and core extraction requires a lot of time and labor, which is a large-scale operation. Also, in the case of the method of chipping out the aged concrete part to the part considered to be the uncarbonated region, the damage to the concrete main body structure also becomes a structural problem, and since it is a manual operation using a chipping machine, it requires a lot of time and labor. In addition, there are problems such as large repair marks remaining.

[0004] Therefore, in recent years, methods have been proposed for minimizing damage to concrete structures and for simply and labor-savingly measuring the carbonation depth.

[0005] For example, in Patent Document 1 below, a drilling hole is made in a concrete structure using a drill, an insertion rod containing a transfer agent is inserted into the drilling hole, and after leaving it for several seconds to more than ten seconds, the insertion rod is pulled out. Since the color of the transfer agent has changed in the part where it was arranged in the non-neutralized part of the insertion rod, the neutralization depth is measured by measuring the length from the part located at the opening end of the drilling hole in the insertion rod to the discolored part.

[0006] Further, in Patent Document 2 below, small holes are provided on the surface of the concrete structure to be tested, an object in the form of a sponge-like or spongy test piece is inserted into these small holes, an injection liquid such as a phenolphthalein solution is injected into this object, and after pulling out the object into which the injection liquid has been injected from the small holes, the neutralization depth is measured by measuring the distance from a pre-recorded point on the surface of the object to the red region due to the reverse coloring of the phenol reaction on the object surface.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] In the case of the methods described in Patent Documents 1 and 2 above, small holes with a relatively small diameter are formed in the concrete, and an indicating material (such as an insertion rod or a spongy test piece) impregnated with an indicator is inserted into these small holes, and it utilizes the fact that the color reaction in the alkaline region of the concrete is transferred to the indicating material.

[0009] However, in the case of these methods, if the contact between the outer surface of the indicator material and the phenolphthalein solution that has undergone a color reaction on the inner wall surface of the concrete is not ensured, there will be parts where the color reaction does not occur firmly, and the transfer of the coloring solution will also be uncertain, so the measurement accuracy of the neutralization depth may deteriorate.

[0010] Also, if too much phenolphthalein solution is injected into the sponge-like test piece, the liquid that has undergone a color reaction will move inside the pores (liquid dripping), and the color reaction region often becomes unclear.

[0011] Therefore, the main problem of the present invention is to provide a method for measuring the neutralization depth of a concrete structure that promotes the color reaction of the phenolphthalein reagent by bringing the indicator material into close contact with the concrete pore wall surface in a pressure-contact state to improve the measurement accuracy, and an indicator material with a specific structure that does not drip liquid.

Means for Solving the Problems

[0012] As the present invention according to claim 1 for solving the above problems, a first step of forming a hole in the concrete structure by drilling, a second step of inserting an indicator material having a phenolphthalein reagent-containing layer supported on the surface side of an elongated base material sheet into the hole, a third step of inserting an expandable and contractible tube that can expand in the radial direction by the fed fluid into the hole space on the back side of the indicator material, a fourth step of promoting the color reaction of the phenolphthalein reagent by feeding air into the expandable and contractible tube to expand the expandable and contractible tube in the radial direction and pressing the indicator material against the hole wall surface from the back side to bring it into close contact in a pressure-contact state, After a predetermined time has elapsed, a fifth step of measuring the neutralization depth by draining the fluid from the expandable and contractible tube to contract it and removing it from the hole, and pulling out the indicator material from the hole and measuring the distance from the position corresponding to the concrete opening end of the indicator material to the colored region is provided, which is a method for measuring the neutralization depth of a concrete structure.

[0013] In the invention described in claim 1 above, after inserting the indicating material into the drill hole, an elastic tube is inserted into the drill hole space on the back side of the indicating material, and the elastic tube is expanded in the radial direction to bring the indicating material into close contact with the hole wall surface from the back side in a pressure contact state, thereby promoting the color reaction of the phenolphthalein reagent. Therefore, the color reaction of the phenolphthalein reagent supported by the indicating material is surely carried out. As a result, the color reaction region becomes clear, so that the measurement accuracy of the neutralization depth can be improved.

[0014] As the invention according to claim 2, there is provided a method for measuring the neutralization depth of a concrete structure according to claim 1, wherein in the first step, the diameter of the drill hole is within 30 mm.

[0015] The invention described in claim 2 above defines a suitable diameter for the drilled hole. Since drilling with a drill causes a defective portion in the main body of the concrete structure, it is desirable to make the diameter as small as possible. Specifically, it is desirable that the diameter of the drill hole is within 30 mm.

[0016] As the invention according to claim 3, there is provided a method for measuring the neutralization depth of a concrete structure according to claim 1, wherein in the second step, marking is performed at a position corresponding to the concrete opening end of the indicating material.

[0017] In the invention described in claim 3 above, it is possible to make the length of the indicating material the same as the length of the drill hole, but it is desirable to provide a protruding portion for the convenience of inserting and removing the indicating material. In this case, by previously marking at a position corresponding to the concrete opening end of the indicating material inserted into the drill hole, in the fifth step, the indicating material can be pulled out from the drill hole and the distance from the position corresponding to the concrete opening end of the indicating material to the color reaction region can be measured.

[0018] As the invention according to claim 4, there is provided a method for measuring the neutralization depth of a concrete structure according to claim 1, wherein the second step and the third step are performed in reverse order.

[0019] The invention according to claim 4 is to reverse the order of the second step and the third step. In claim 1, after inserting the indicating material 1 (the second step), the procedure of inserting the elastic tube 6 (the third step) is adopted. However, after inserting the elastic tube 6, it is also possible to adopt the procedure of inserting the indicating material 1, that is, to reverse the order of the second step and the third step.

[0020] As the invention according to claim 5, there is provided an indicating material for a method of measuring the carbonation depth of a concrete structure according to any one of claims 1 to 4, characterized in that a phenolphthalein reagent-containing layer is supported on the surface side of an elongated base material sheet.

[0021] The invention according to claim 5 described above describes an indicating material for a method of measuring the carbonation depth of a concrete structure as a separate independent claim.

[0022] As the invention according to claim 6, there is provided an indicating material for a method of measuring the carbonation depth of a concrete structure according to claim 5, wherein the phenolphthalein reagent-containing layer is a layer containing a phenolphthalein reagent in a transparent gel layer.

[0023] The invention according to claim 6 described above is such that in the indicating material, the phenolphthalein reagent-containing layer is a layer containing a phenolphthalein reagent in a transparent gel layer. By containing a phenolphthalein reagent in a transparent gel substance, it becomes possible to eliminate dripping of the liquid and to reduce the amount of phenolphthalein reagent used.

Effects of the Invention

[0024] As described in detail above, according to the present invention, by bringing the indicating material into close contact with the concrete hole wall surface in a pressure-contact state, the color reaction of the phenolphthalein reagent can be promoted and the measurement accuracy can be improved. In addition, it becomes possible to provide an indicating material in which the phenolphthalein reagent does not drip.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0026] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0027] Before explaining the method for measuring the carbonation depth of a concrete structure according to the present invention, we will explain the indicator 1 for the carbonation depth measuring method and the expandable tube device 4 consisting of a radially expandable expandable tube 6 and an air supply means 5.

[0028] As shown in FIG. 1, the indicating material 1 is a phenolphthalein reagent-containing layer 3 supported on the surface side of a long and narrow base sheet 2. Various materials can be used for the base sheet 2. For example, paper, cloth, aluminum foil, aluminum vapor deposition film, nonwoven fabric, and plastic films such as polypropylene (abbreviation: PP), polyethylene (abbreviation: PE), polyvinyl chloride (abbreviation: PVC), and polyester can be used. It is desirable that the thickness has a certain degree of rigidity, and that the rigidity is such that the end does not bend midway or hang down in a curved shape when held by hand when inserting into a perforation.

[0029] The width dimension B of the indicating material 1 is set to a dimension larger than the diameter of the perforation, and after being inserted into the perforation in a curved state in a cross-sectional view, the force is released and expanded so that both ends come into contact with both side walls in the perforation and are held in a curved state in the perforation (the state of (A) in Fig. 5). Regarding the length L, it is desirable to make it the same as the length of the perforation formed in the concrete structure, or to make it slightly longer than the length of the perforation so as to have a protruding portion for the convenience of inserting and removing the indicating material 1.

[0030] As the phenolphthalein reagent-containing layer 3, it is desirable to use a layer in which a phenolphthalein reagent is contained in a transparent gel layer. That is, it is desirable to use a mixture of a gelling agent / thickener, a water-retaining solvent, a phenolphthalein reagent, and water.

[0031] There are no particular limitations on the gelling agent / thickener for forming the transparent gel, but pectin, gelatin, carrageenan, xanthan gum, methylcellulose, guar gum, tara gum, gum arabic, gellan gum, alginic acid, ultra-soft urethane resin, etc. can be used.

[0032] Also, it is desirable to contain a water-retaining solvent to prevent hardening. Examples of the water-retaining solvent include glycerin, glycols such as ethylene glycol, propylene glycol, butylene glycol, dipropylene glycol, isoprene glycol, and polyethylene glycol. These water-retaining solvents can also be used alone or in combination of two or more.

[0033] As the phenolphthalein reagent, it is desirable to use the phenolphthalein solution specified in JA.5 of JIS K 8001 specified in JIS A 1152 (Method for Measuring the Carbonation Depth of Concrete). Specifically, it is desirable to use a solution obtained by weighing 1.0 g of phenolphthalein, dissolving it in 90 ml of ethanol (95), and making it up to 100 ml with water.

[0034] Next, the telescopic tube device 4 will be described with reference to FIG. 2. The telescopic tube device 4 is a device comprising an air supply means 5 and a telescopic tube 6 that can expand in the radial direction. The illustrated air supply means 5 is an air supply means with a piston structure. It consists of a piston 5A and a cylinder 5B, and by pushing out the piston 5A, compressed air can be sent. As the air supply means 5, it is also possible to use a handy type compressed air feeder that can be held by hand, an air pump device driven by electricity, or the like. As the telescopic tube 6, a cylindrical or flat rubber tube can be used, but considering the ease of insertion into the perforation, it is desirable to attach an elongated rigid member 7 such as a plastic bar along the telescopic tube 6.

[0035] 〔Method for Measuring Carbonation Depth of Concrete Structure〕 Next, based on FIGS. 3 to 5, the method for measuring the carbonation depth of a concrete structure according to the present invention will be described in detail.

[0036] <First Step> In the first step, as shown in FIG. 3(A), a small-diameter perforation 12 is formed in the concrete structure 10 by an electric drill 11. The diameter φ of the perforation 12 is within 30 mm, preferably within 20 mm, and more preferably within 15 mm. Regarding the length S, it is within 30 cm, preferably within 20 cm, and preferably within 10 cm. It is desirable to minimize the damage to the concrete structure 10 by making the perforation 12 as small as possible.

[0037] <Second Step> In the second step, as shown in FIG. 3(B), an indicator 1 having a phenolphthalein reagent-containing layer 3 supported on the surface side of an elongated base material sheet 2 is inserted into the perforation 12.

[0038] When the indicator 1 protrudes outside the perforation 12, as shown in FIG. 3(C), marking is performed with a pen 13 at the position corresponding to the concrete opening end of the indicator 1.

[0039] <Step 3> In the third step, as shown in FIG. 3(D), an expandable and contractible tube 6 that can expand radially by the fed air is inserted into the perforated space on the back side of the indicating material 1.

[0040] <Step 4> In the fourth step, as shown in FIG. 4(E), the expandable and contractible tube 6 is expanded radially by feeding air into the expandable and contractible tube 6, and the indicating material 1 is pressed against the hole wall surface from the back side and brought into close contact in a pressure contact state to promote the color reaction of the phenolphthalein reagent. That is, as shown in FIG. 5(A), with the indicating material 1 and the expandable and contractible tube 6 inserted into the perforation 12, the expandable and contractible tube 6 is expanded radially by feeding air into the expandable and contractible tube 6, and as shown in FIG. 5(B), the indicating material 1 is pressed against the hole wall surface from the back side and brought into close contact in a pressure contact state. Since the phenolphthalein reagent carried on the front surface side of the indicating material 1 is firmly held in close contact with the hole wall surface, the phenolphthalein reagent changes to red in the region where the alkalinity of the concrete is maintained. The phenolphthalein reagent changes to red at the concrete contact portion, and the changed phenolphthalein reagent is transferred to the indicating material 1 side.

[0041] <Step 5> In the fifth step, as shown in FIG. 5(F), after a predetermined time has elapsed, the air is removed from the expandable and contractible tube 6 to contract it and it is removed from the perforation 12, and as shown in FIG. 5(G), the indicating material 1 is pulled out from the perforation 12 and the neutralization depth is measured by measuring the distance from the position corresponding to the concrete opening end of the indicating material 1 to the colored region. Specifically, as shown in FIG. 6, the distance (neutralization depth) from the marking position of the indicating material 1 to the color reaction region is measured.

[0042] <Step 6> In the sixth step, as shown in FIG. 5(H), a filler 14 such as non-shrinking mortar or epoxy resin is injected into the perforation 12 to fill the perforation 12.

[0043] 〔Other exemplary forms〕 (1) In the above exemplary form, as the indicating material 1, a material in which a phenolphthalein reagent-containing layer 3 is supported on the surface side of an elongated base sheet 2 was used. However, a material in which a phenolphthalein reagent is sprayed or applied on the surface side of the base sheet 2 immediately before being inserted into the perforation 12 may also be used.

[0044] (2) In the above exemplary form, after inserting the indicating material 1 (second step), the procedure of inserting the elastic tube 6 (third step) was adopted. However, it is also possible to reverse the order of the second step and the third step, that is, to insert the indicating material 1 after inserting the elastic tube 6.

[0045] (3) In the above exemplary form, air was used as the fluid for expanding the elastic tube 6. However, it is also possible to use a liquid such as water or oil as the fluid.

Explanation of reference numerals

[0046] 1... Indicating material, 2... Base sheet, 3... Phenolphthalein reagent-containing layer, 4... Elastic tube device, 5... Air supply means, 6... Elastic tube, 7... Rigid member, 10... Concrete structure, 11... Electric drill, 12... Perforation, 13... Pen, 14... Filling material

Claims

1. A first step of forming a hole by drilling in a concrete structure; A second step of inserting an indicating material having a phenolphthalein reagent-containing layer supported on the surface side of an elongated base material sheet into the hole; A third step of inserting an expandable and contractible tube that can expand radially by a fed fluid into the hole space on the back side of the indicating material; A fourth step of promoting the color reaction of the phenolphthalein reagent by feeding air into the expandable and contractible tube to expand the expandable and contractible tube radially, pressing the indicating material against the hole wall surface from the back side and bringing it into close contact in a pressure contact state; A fifth step of, after a lapse of a predetermined time, extracting the fluid from the expandable and contractible tube to contract it and removing it from the hole, pulling out the indicating material from the hole, and measuring the neutralization depth by measuring the distance from the position corresponding to the concrete opening end of the indicating material to the colored region. A method for measuring the neutralization depth of a concrete structure, characterized by comprising the above steps.

2. The method for measuring the neutralization depth of a concrete structure according to Claim 1, wherein in the first step, the diameter of the hole is within 30 mm.

3. The method for measuring the neutralization depth of a concrete structure according to Claim 1, wherein in the second step, marking is performed on the position corresponding to the concrete opening end of the indicating material.

4. The method for measuring the neutralization depth of a concrete structure according to Claim 1, wherein the second step and the third step are performed in reverse order.

5. An indicating material for the method for measuring the neutralization depth of a concrete structure according to any one of Claims 1 to 4, characterized in that a phenolphthalein reagent-containing layer is supported on the surface side of an elongated base material sheet.

6. The indicating material for the method for measuring the neutralization depth of a concrete structure according to Claim 5, wherein the phenolphthalein reagent-containing layer is a layer containing a phenolphthalein reagent in a transparent gel layer.

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