Method for evaluating the water absorption of concrete

Abstract

To provide a method for easily and accurately evaluating water absorption of concrete.SOLUTION: A method for evaluating water absorbability of concrete measures mass of a material having viscosity, elasticity, and water, brings the material having viscosity, elasticity, and water into contact with the surface of concrete, removes the material having viscosity, elasticity, and water from the surface of the concrete after a predetermined time has passed, measure weight of the material having viscosity, elasticity, and water after the material having viscosity, elasticity, and water is removed from the surface of the concrete, and then compares the weight of the material having viscosity, elasticity, and water before and after the material having viscosity, elasticity, and water is brought in contact with the surface of the concrete.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One embodiment of the present invention relates to a method for evaluating the water absorption of concrete.

Background Art

[0002] It is known that concrete has a higher water absorption rate than natural stone. The magnitude of the water absorption rate is regarded as an index indicating the durability of concrete, particularly the loss of alkalinity, and various methods have been proposed for its measurement method. As a method for evaluating the water absorption of the concrete surface, a method of measuring the change (decrease) in the amount of water by bringing water or a water-containing sponge into contact with the concrete surface has been disclosed (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, if surface bubbles (recesses) derived from air are formed on the concrete surface, in the measurement method of filling water into a measurement container having an opening as disclosed in Patent Document 1, there is a problem that water seeps out from the measurement area and accurate measurement cannot be performed. In particular, there is a problem that it is difficult to attach the measurement container to the wall surface or ceiling surface of the concrete. Further, as disclosed in Patent Document 2, in the method using a sponge having water absorption, the sponge is not always in contact with the concrete surface, and since the concrete surface itself also has a non-smooth surface (recesses) such as surface bubbles, it is considered difficult to accurately evaluate the water absorption.

[0005] One embodiment of the present invention has been made in view of such problems and aims to provide a simple and accurate method for evaluating the water absorption of concrete. [Means for solving the problem]

[0006] A method for evaluating the water absorption of concrete according to one embodiment of the present invention involves measuring the mass of a substance that is viscous, elastic, and water-containing; bringing the viscous, elastic, and water-containing substance into contact with the surface of the concrete; removing the viscous, elastic, and water-containing substance from the surface of the concrete after a certain period of time; measuring the weight of the viscous, elastic, and water-containing substance after removal; and comparing the weight of the viscous, elastic, and water-containing substance before and after contact with the surface of the concrete.

[0007] In one embodiment of the present invention, when a substance having viscosity, elasticity, and water content is brought into contact with the surface of concrete, it is preferable to cover the substance having viscosity, elasticity, and water content with a water-impermeable coating material.

[0008] In one embodiment of the present invention, a non-permeable measuring container having an opening may be filled with a viscous, elastic, and water-containing substance, and the opening may be brought into contact with the surface of the concrete, thereby bringing the viscous, elastic, and water-containing substance into contact with the surface of the concrete.

[0009] In one embodiment of the present invention, when a substance having viscosity, elasticity, and water content is brought into contact with the surface of concrete, a frame material may be placed on the surface of the concrete, and the substance having viscosity, elasticity, and water content may be filled into the frame material.

[0010] In one embodiment of the present invention, a water-absorbing polymer may be used as the substance having viscosity, elasticity, and water content. As the water-absorbing polymer, polyacrylate-based, starch-acrylate graft polymer, vinyl acetate copolymer, maleic anhydride copolymer, polyvinyl alcohol-based, and carboxymethylcellulose (CMC)-based polymers may be used. [Effects of the Invention]

[0011] According to a method for evaluating the water absorption of concrete according to one embodiment of the present invention, by bringing a substance that has viscosity, elasticity, and water content into contact with the concrete surface and evaluating the water absorption, it is possible to measure even if there are depressions such as surface air bubbles on the concrete surface, and the contact can be made in accordance with the shape of these depressions, thus enabling accurate evaluation of water absorption. [Brief explanation of the drawing]

[0012] [Figure 1] This figure illustrates a method for evaluating the water absorption of concrete according to one embodiment of the present invention, where (A) is a plan view when a substance having viscosity and elasticity and water content is brought into contact with the surface of concrete, and (B) is a cross-sectional view corresponding to the area between A1 and B1. [Figure 2] This figure illustrates a method for evaluating the water absorption of concrete according to one embodiment of the present invention, where (A) is a plan view when a substance having viscosity and elasticity and water content is brought into contact with the surface of concrete, (B) is a cross-sectional view corresponding to the area between A2 and B2, and (C) shows a configuration in which an injection port is provided in the measuring container. [Figure 3] This figure illustrates a method for evaluating the water absorption of concrete according to one embodiment of the present invention, where (A) is a plan view when a substance having viscosity and elasticity and water content is brought into contact with the surface of concrete, and (B) is a cross-sectional view corresponding to the area between A3 and B3. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described below. In order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each drawing, elements similar to those described above with respect to previously shown drawings are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate. Furthermore, the words "first," "second," etc., appended to each element are convenient indicators used to distinguish each element and have no further meaning unless specifically explained.

[0014] A method for evaluating the water absorption of a concrete surface according to one embodiment of the present invention can be used to evaluate the water absorption of the surface of a concrete structure, or of a crack repair portion or cross-sectional repair portion of a concrete structure. The details thereof will be described below with reference to the drawings.

[0015] To evaluate the water absorption of a concrete surface, a fluid substance containing water is used. In other words, to evaluate the water absorption of a concrete surface, a viscoelastic substance that possesses both the viscosity of a liquid and the elasticity of a solid, and is both fluid and water-containing, is used. Such a substance is sometimes called "slime," but in this embodiment, it will be called a "viscoelastic water-containing substance." Viscoelastic water-containing substances do not have a fixed shape, and when evaluating the water absorption of concrete, a certain amount is spread and adhered to the concrete surface.

[0016] Figures 1(A) and (B) show the state when a viscoelastic water-containing substance 102 is brought into contact with the surface of concrete 200 in order to test the water absorption of the concrete. In Figure 1, (A) is a plan view, and (B) is a cross-sectional view corresponding to the section between A1 and B1.

[0017] As shown in Figures 1(A) and (B), the viscoelastic water-containing substance 102 does not have a fixed shape, but when evaluating water absorption, it can be spread over a certain area on the surface of the concrete 200. Because the viscoelastic water-containing substance 102 is fluid, it can be spread and brought into contact with any area on the surface of the concrete 200. Furthermore, because the viscoelastic water-containing substance 102 is fluid, as shown in the inset in Figure 1(B), even if there are depressions such as fine surface bubbles on the surface of the concrete 200, it can conform to the shape and adhere to them. In addition, although not shown, even if the surface of the concrete 200 has a stepped shape, the viscoelastic water-containing substance 102 can adhere to the stepped portion.

[0018] When the viscoelastic water-containing substance 102 is brought into contact with the surface of the concrete 200, a water-impermeable coating material 104 is used to prevent the contained moisture from evaporating into the air. The coating material 104 is provided so as to cover the surface of the viscoelastic water-containing substance 102. The coating material 104 may have a sheet-like shape that can cover the viscoelastic water-containing substance 102, or it may have a container-like shape.

[0019] The covering material 104 may be a flexible and water-impermeable sheet material. A resin sheet may be used as such a sheet material. Examples of resin sheets include polyethylene, polyethylene terephthalate, polyethylene naphthalate, polyvinyl chloride resin, polystyrene, acrylic, polycarbonate, polyphenylene sulfide, fluororesin, polyetheretherketone, polyethersulfone, aramid, and polyimide.

[0020] Figures 2(A) and (B) show the case where the coating material 104 has the shape of the measuring container 106. In Fig. 2, (A) shows a plan view, and (B) shows a cross-sectional view corresponding to between A2 - B2. The measuring container 106 as the coating material 104 has a main body 1062 for accommodating the viscoelastic water-containing substance 102 and an opening 1063 provided in the main body 1062 for exposing the viscoelastic water-containing substance 102. The shapes of the main body 1062 and the opening 1063 in plan view are arbitrary, and are preferably circular, elliptical, rectangular, polygonal, or the like.

[0021] The measuring container 106 may have a contact portion 1064 surrounding the periphery of the opening 1063, and the contact portion 1064 may be in contact with the surface of the concrete 200. By providing the contact portion 1064, the main body 1062 can be stably held on the surface of the concrete 200. The surface of the contact portion 1064 contacting the concrete 200 may have re-peelability. The surface having re-peelability may be provided with an adhesive 1066 having adhesiveness and bonding property. For example, an acrylic adhesive, a silicone adhesive, a urethane adhesive, or a rubber-based adhesive may be applied to the contact portion 1064 as the adhesive 1066. By having a contact surface with both adhesiveness and bonding property for the contact portion 1064, when evaluating water absorption, the measuring container 106 can be attached to the surface of the concrete 200 so that the attachment position does not move during measurement, and the measuring container 106 can be easily removed after measurement.

[0022] Also, although not shown, the measuring container 106 may have a structure for attaching to the surface of the concrete 200 by physical engagement means (screws, fixing hooks, etc.), magnetic adhesion means (magnets), etc. instead of the adhesive 1066.

[0023] The size (capacity) of the main body 1062 of the measuring container 106 and the size of the opening 1063 are appropriately set. The size of the contact portion 1064 can be appropriately changed according to the size of the main body 1062, but in order to fix the main body 1062 in close contact with the surface of the concrete 200, it preferably has a width of about 20 mm to 150 mm.

[0024] As shown in Figure 2(C), the measuring container 106 may be provided with an injection port 1068 for injecting a viscoelastic water-containing substance. Having an injection port 1068 allows the viscoelastic water-containing substance 102 to be poured in while the measuring container 106 is attached to the surface of the concrete 200. With the measuring container 106 having such a configuration, accurate measurements can be performed because the measuring container 106 can be placed against the surface of the concrete 200 to determine the measurement position, and then the viscoelastic water-containing substance can be poured in and brought into contact with the concrete 200.

[0025] As shown in Figures 2(A) and (B), by using the measuring container 106 as a covering material 104, the viscoelastic water-containing substance 102 can be brought into contact with concrete walls and ceilings, and water absorption can be evaluated.

[0026] Figures 3(A) and (B) show an embodiment in which the frame material 108 is brought into contact with the surface of the concrete 200 and the inside of the frame material 108 is filled with a viscoelastic water-containing substance 102. In Figure 3, (A) is a plan view and (B) is a cross-sectional view corresponding to the section between A3 and B3.

[0027] As shown in Figures 3(A) and (B), by using the frame material 108, the area in contact with the surface of the concrete 200 by the viscoelastic water-containing substance 102 can be kept constant. Furthermore, by providing a covering material 104 to cover the area enclosed by the frame material 108, evaporation of water from the viscoelastic water-containing substance 102 can be prevented. By defining the area in contact with the concrete 200 by the viscoelastic water-containing substance 102 in this way, the amount of water absorbed per unit area can be evaluated.

[0028] In this embodiment, a water-absorbing polymer can be used as the viscoelastic water-containing substance 102. Examples of water-absorbing polymers include polyacrylate-based polymers, starch-acrylate graft polymers, vinyl acetate copolymers, maleic anhydride copolymers, polyvinyl alcohol-based polymers, and carboxymethylcellulose (CMC)-based polymers. Sodium polyacrylate can be used as a specific example.

[0029] When the viscoelastic water-containing substance 102 is brought into contact with concrete 200, the water content of the viscoelastic water-containing substance 102 decreases due to the water absorption of the concrete 200. Therefore, the water absorption of the concrete 200 can be evaluated by examining the weight change of the viscoelastic water-containing substance 102 before and after contact with the concrete 200.

[0030] Preferably, the water content of the viscoelastic water-containing substance 102 is pre-adjusted to evaluate the water absorption of the concrete 200.

[0031] The moisture contained in the viscoelastic water-containing substance 102 seeps into the concrete and moves into its interior depending on the condition of the concrete. For example, if the density of the concrete 200 is low, the water absorption will increase, and more moisture will seep into the concrete from the viscoelastic water-containing substance 102. Also, if cracks occur in the concrete 200, the water absorption will increase, so more moisture will seep into the concrete from the viscoelastic water-containing substance 102 compared to when there are no cracks.

[0032] As described above, concrete has water absorption properties, and the degree of water absorption varies depending on the material and condition of the concrete. Therefore, the water absorption of concrete can be evaluated by comparing the weight before and after the viscoelastic water-containing substance 102 is brought into contact with the concrete surface. In other words, the greater the weight change of the viscoelastic water-containing substance 102, the higher the water absorption of the concrete can be evaluated. The time for which the viscoelastic water-containing substance is brought into contact with the concrete surface is arbitrary, but accurate measurement can be obtained by keeping it in contact for a certain period of time.

[0033] As described in this embodiment, the viscoelastic water-containing substance 102 does not have shape retention, but because it has viscosity and elasticity, it is easier to handle compared to when water is brought into direct contact with concrete. Furthermore, because the viscoelastic water-containing substance 102 is fluid, it can conform to the shape of any depressions such as surface air bubbles on the concrete surface, allowing for accurate evaluation.

[0034] Thus, according to this embodiment, a water absorption test of the concrete surface can be performed by first measuring the weight of the viscoelastic water-containing substance 102, bringing the viscoelastic water-containing substance 102 into contact with the surface of the concrete 200, removing the viscoelastic water-containing substance 102 from the surface of the concrete 200 after a certain period of time, measuring the weight of the viscoelastic water-containing substance 102 at that time, and evaluating the weight change before and after contact.

[0035] This method of evaluating water absorption can be applied to various structures using concrete. It is not limited to specific types of concrete and can be applied to various types of concrete, including general structural concrete, high-strength concrete, fluidized concrete, and prestressed concrete. Furthermore, it can be used to evaluate whether repairs to cracks or deteriorated areas of concrete have been carried out appropriately. [Explanation of Symbols]

[0036] 102: Viscoelastic water-containing substance, 104: Covering material, 106: Measuring container, 1062: Main body, 1063: Opening, 1064: Contact part, 1066: Adhesive, 1068: Inlet, 108: Frame material, 200: Concrete

Claims

1. Measuring the mass of a viscoelastic water-containing substance that is fluid and does not have a fixed shape, A viscoelastic, water-containing substance that is fluid and does not retain its shape is brought into contact with the surface of the concrete. After a certain period of time has elapsed, the viscoelastic water-containing substance that is fluid and does not retain its shape is removed from the surface of the concrete. The weight of the viscoelastic water-containing substance that is fluid and has no fixed shape after removal is measured. A method for evaluating the water absorption of a concrete surface, characterized by comparing the weight of the aforementioned fluid and non-shape-retaining viscoelastic water-containing substance before and after contact with the concrete surface.

2. The method for evaluating the water absorption of a concrete surface according to claim 1, wherein when the viscoelastic water-containing substance having fluidity and not being shaped is brought into contact with the surface of the concrete, the viscoelastic water-containing substance having fluidity and not being shaped is covered with a non-permeable coating material.

3. A method for evaluating the water absorption of a concrete surface according to claim 1, comprising filling a non-permeable measuring container having an opening with the fluid and non-shape-retaining viscoelastic water-containing substance, and bringing the opening into contact with the surface of the concrete, thereby bringing the fluid and non-shape-retaining viscoelastic water-containing substance into contact with the surface of the concrete.

4. A method for evaluating the water absorption of a concrete surface according to claim 1 or 2, wherein when the viscoelastic water-containing substance having fluidity and not being shaped is brought into contact with the surface of the concrete, a frame material is placed on the surface of the concrete and the viscoelastic water-containing substance having fluidity and not being shaped is filled into the frame material.

5. The method for evaluating the water absorption of a concrete surface according to any one of claims 1 to 4, wherein the viscoelastic water-containing substance having fluidity and not being morphologically fixed is a water-absorbing polymer.

6. The method for evaluating the water absorption of a concrete surface according to claim 5, wherein the water-absorbing polymer is a polyacrylate-based, starch-acrylate graft polymer, vinyl acetate copolymer, maleic anhydride copolymer, polyvinyl alcohol-based, or carboxymethylcellulose (CMC)-based polymer.

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