JP4970089B2 - Crack specimen and method for repairing cracks using the specimen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crack sample that can be manufactured easily in a short time, and easily generate a crack of a desired width at a desired position. <P>SOLUTION: This crack sample 1 is produced by sticking a band-like constraint body 3 formed of a carbon fiber collection plate to the back surface of a plate body 2 of a substantially rectangular top surface made of concrete so that it crosses the plate body 2 in a diagonal shape. The crossing part of the constraint body 3 is hit from the back side of the plate body 2 with a hammer 4 or the like, thereby generating the desired crack on the front side of the plate body 2. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a crack specimen that is artificially cracked in concrete or the like and used for an experiment such as repair, and a crack repair experiment method using the specimen.

  Cracks (cracks) occur in concrete due to external forces, temperature changes, internal stress due to shrinkage and expansion, and strain. As a repair method for cracked concrete, an epoxy resin-based injection material is generally used to reinforce the crack. In addition, a minute crack having a width of about 0.3 mm or less, which has no problem in terms of durability, may be concealed by applying an elastic paint on the surface in order to maintain an aesthetic appearance.

  In the repair method of filling the cracked filler with the injection material, the purpose is to check the filling state of the injection material, the strength after injection, followability, etc., and to train the repair technology to the workers. An injection experiment may be performed using a specimen that has cracked. In this case, the concrete specimen must be cracked in advance with a desired width.

  In addition, in the repair method of applying an elastic paint to the concrete surface, an experiment was made to artificially generate a crack later on the specimen coated with the elastic paint for the purpose of confirming the followability of the coating film to the crack. May be performed. In this case, a technique for generating a crack having a desired width later at a desired position of the specimen coated on the surface is required.

However, conventionally, as a specimen for artificially generating cracks in concrete, only a so-called ring-shaped (doughnut-shaped) specimen as described in, for example, Patent Document 1 is known. Is the actual situation. As shown in FIG. 6, the ring-shaped specimen 9 is formed by placing a metal annular restraint 91 on the inner side and placing concrete 92 in a ring shape on the outer side. By utilizing the difference in the amount of drying shrinkage, a crack 93 is induced on the outer peripheral side.
JP 2001-165831 A

  The above-mentioned conventional ring-shaped specimens are those that naturally generate cracks after the cast concrete has dried, so the width and length of the cracks, the position at which the cracks are generated, etc., depending on the purpose of the experiment. It is extremely difficult to adjust freely.

  As another means for artificially cracking concrete, it is conceivable to hit a concrete board of an appropriate size with a hammer or the like. However, in the case of an unreinforced concrete plate, the concrete plate breaks with the occurrence of cracks, so a concrete plate with a reinforcing bar inside is required. Production of such a specimen requires steps such as form creation, reinforcement, concrete placement, curing / drying, demolding, and time and labor are required until completion. In addition, it is also difficult to generate a crack having a desired width while adjusting the strength of the hitting of the concrete plate in which the reinforcing bars are arranged.

  In an experiment for confirming the followability of an elastic paint, it is necessary to generate a crack on the lower side of the paint film after the paint is applied. However, in the specimen as described above, since cracks occur at irregular positions with irregular widths, it is difficult to specify the position and width of cracks from the top of the coating film.

  The present invention has been made in view of such circumstances, and provides a crack specimen that can be easily produced in a short period of time and can easily generate a crack of a desired width at a desired position. For the purpose.

  In addition, the present invention provides a practical crack repair experiment method using the specimen.

In order to achieve the above-described object, the cracked specimen of the present invention is a cracked specimen for artificially generating cracks in concrete or the like and used for a repair experiment for cracks. It is characterized as a belt-like restraint made of carbon fiber laminated plates attached to the back of the body so as to cross the diagonal of the plate.

  Furthermore, the cracked specimen of the present invention is characterized in that a crack is generated on the front side of the plate by hitting the intersection of the restraint from the back side of the plate.

  In addition, as a crack repair experiment method using the above-mentioned cracked specimen, first, the injection material was injected into the cracks generated as described above, and then the injection portion was cut to confirm the state of the injection material The method of doing can be mentioned.

  Alternatively, after injecting the injection material into the crack generated in the same manner, after the injection material is hardened, the crossing portion of the restraint body is hit again from the back side of the plate body to generate a crack on the front side of the plate body. A method can also be mentioned.

  As another crack repair experiment method, an elastic paint is applied to an appropriate range of the center portion of the surface of the cracked specimen before cracking, and then the crossing portion of the restraint is hit from the back side of the cracked specimen. And a method of generating cracks around the coating range on the front side of the plate.

  Since the cracked specimen of the present invention configured as described above is simply a belt-like restraint made of carbon fiber laminated plates attached to one side of an unreinforced plate with an adhesive, it is extremely easy. And can be manufactured in a short period of time. And the crack of a desired width | variety can be easily generate | occur | produced in a substantially regular position only by striking the crossing part of a restraint body, adjusting strength. Therefore, by utilizing this crack specimen, various repair experiments for cracks can be carried out efficiently and accurately.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a cracked specimen 1 according to an embodiment of the present invention. The illustrated crack specimen 1 is obtained by attaching a restraint 3 made of a carbon fiber laminated plate to the back surface of a plate 2 made of cement concrete.

  A carbon fiber plate (CCF plate) is obtained by firing a residual pitch of petroleum / coal at a high temperature, and has a very high tensile strength and tensile elastic modulus while being lightweight. In recent years, it is marketed as a long material having a width of 5 cm and a thickness of 1.2 mm, and has begun to be used for reinforcement work of concrete structures in the field of civil engineering and architecture. The restraint body 3 made of the carbon fiber laminated board is attached to one side of the plate body 2 made of concrete or the like instead of a reinforcing bar (in the present specification, this face is referred to as a “back face” for convenience). Thus, the elongation of the back side of the plate body 2 is restricted. An epoxy resin adhesive can be suitably used for attaching the restraint 3. However, the adhesive is not limited to this as long as sufficient adhesive strength is obtained.

  The restraint body 3 is stuck and crossed in a diagonal line shape of the plate body 2. At the side of the intersecting portion, the restraining body 3 that overlaps the outside slightly floats from the surface of the plate body 2, but there is no problem as long as both end portions are securely attached. The practical size of the plate body 2 is about 30 to 45 cm long side × 20 to 30 cm short side × thickness 6 to 8 cm. However, this size can be appropriately changed according to the purpose of the experiment. The restraint body 3 can also be appropriately changed in a practical range of width 4 to 6 cm and thickness 1 to 1.5 mm.

  In order to generate cracks, after curing the adhesive for several hours, as shown in FIG. 2, with the plate 2 placed on an appropriate rootstock, the crossing portion of the restraint 3 is hammered from the back side. Strike with 4 mag. Then, a crack occurs on the opposite surface (in this specification, this surface is called “surface” for convenience). Since the restraint body 3 is stuck on the diagonal line of the plate body 2, as shown in FIG. 3, the crack 5 is almost regularly parallel to the short side of the plate body 2 from the center portion of the plate body 2. Occur in any direction. In this respect, the shape of the plate body 2 is preferably rectangular rather than square.

  The width of the crack 5 can be easily adjusted by adjusting the strength and number of hits while checking the width of the crack 5 each time it is hit. Since the back side of the plate body 2 is firmly restrained by the restraint body 3, even if the depth and length of the crack 5 are increased, the plate body 2 is not completely broken. In addition to the hammer, for example, a concrete compressor, a bending tester, an impact tester, and other pressure-adjustable machines can be used as the hitting means for the plate 2.

  In a crack repair experiment using an injection material such as an epoxy resin or an acrylic resin, the crack specimen 1 in which the crack 5 is generated in advance as described above is used. After filling the crack 5 having a desired width with the injection material, the injection portion is cut, or the cylindrical core 6 is removed as shown in FIG. Strength, followability, etc. can be easily confirmed.

  Or after the injection material with which the crack 5 was filled hardens | cures, it can strike again from the back surface of the plate body 2, and the new crack which arises in another part can also be verified. Such an experiment can also be used as a demonstration of crack repair effects.

  On the other hand, in the crack repair experiment for confirming the followability of the elastic paint, first, as shown in FIG. 5, the paint 7 is applied to the crack specimen 1 before the crack 5 is generated. The application range is an appropriate range including the central portion of the surface of the plate 2, and a portion where the coating material 7 is not applied is also left around. When the application is finished, as shown in FIG. 2, the crossing portion of the restraining body 3 is hit from the back side of the cracked specimen 1, and a crack 5 is generated on the front side of the plate body 2. According to the cracked specimen 1 of the present invention, the cracks 5 are generated almost regularly in the short side direction from the central portion of the plate body 2, so that the vicinity of the boundary between the portion where the coating 7 is applied and the portion where the coating 7 is not applied (see FIG. By measuring the width of the crack 5 in the encircled portion 5), the width of the crack 5 on the lower side of the coating film can be specified with high accuracy.

Thus, by using the cracked specimen 1 of the present invention, it is possible to accurately carry out experiments related to crack repair and inspection in addition to the above. In the present invention, concrete “etc.” is not only so-called cement concrete, but also concrete materials in a broad sense in which various aggregates are hardened with binders such as cement, lime, gypsum, asphalt, plastic, and clay. It includes bricks mainly composed of

It is a perspective view of the crack test piece which concerns on embodiment of this invention. It is explanatory drawing of the operation | work which produces a crack in the said crack specimen. It is a top view which shows the state of the crack which arises in the said crack specimen. It is explanatory drawing of the crack repair experiment which confirms the filling state of an injection material using the said crack test piece. It is explanatory drawing of the crack repair experiment figure which confirms the followable | trackability of an elastic coating material using the said crack test piece. It is a perspective view which shows an example of the conventional crack test piece.

Explanation of symbols

1 Crack specimen 2 Plate 3 Restraint 5 Crack 7 Paint

Claims (5)

A crack specimen for artificially generating cracks in concrete, etc., and for use in repair tests for cracks,
A crack specimen in which a band-like restraint made of carbon fiber laminated plates is adhered to the back of a substantially rectangular plate made of concrete or the like so as to cross the diagonal of the plate.   The crack specimen according to claim 1, wherein a crack is generated on the front side of the plate body by hitting an intersecting portion of the restraint body from the back side of the plate body.   A method for repairing cracks, comprising injecting an injection material into a crack in the crack specimen according to claim 2 and then cutting the injection portion to check the state of the injection material.   After injecting the injection material into the inside of the crack in the cracked specimen according to claim 2, after the injection material is hardened, the crossing portion of the restraint body is hit again from the back side of the plate body, and the crack is formed on the front side of the plate body. A crack repair experiment method characterized by generating.   After applying an elastic coating to an appropriate range of the surface center portion in the cracked specimen according to claim 1, hitting the intersecting portion of the restraining body from the back side of the cracked specimen, the periphery of the coating range on the front side of the plate A crack repair experiment method characterized by generating cracks in the crack.

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