JP2007239257A - Concrete structure repairing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete structure repairing method for repairing damage in the vicinity of a cut surface, that occurs due to cutting work in the process of repairing/reinforcing work of a concrete structure, and particularly a repairing method effective for minute cracks not visually detected. <P>SOLUTION: According to the method, a two-part mixing type adhesive synthetic resin composition 2 obtained by mixing a synthetic resin-based solvent and a hardener therefor to each other, and having a viscosity of less than 100 mPa s/20°C, is applied to a concrete surface having been subjected to cutting processing in the repairing/reinforcing work of the concrete structure 1, and after the lapse of a necessary curing time period, a cement-based concrete-jointing material 3 is placed on a surface where the adhesive synthetic resin compound 2 is applied. The adhesive synthetic resin compound 2 applied to the concrete surface has a very low viscosity, and therefore it excellently penetrates very minute cracks 1b each having a width of 0.01 mm or less and not detected visually, which results in increased adhesive strength of the cement-based concrete-jointing material 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for repairing damage in the vicinity of a cutting surface, particularly fine cracks that cannot be visually observed, generated by a cutting operation performed during repair or reinforcement work of a concrete structure.

  As a method of repairing and reinforcing concrete structures such as tunnel structures, bridge slabs and piers, pile foundations, underground structures, piers and revetments, dams and embankments, etc. Newly known methods such as transferring healthy concrete and repair / reinforcement materials are known. This suspension process employs a water jet method that cuts with water pressure, a breaker method that uses a cutting device attached to a large machine, a spiky hammer method, or a manual cutting operation that uses an electric pick. .

In the suspension treatment by these methods, the existing concrete may be damaged, such as cracks, which may adversely affect the adhesive properties of the existing concrete and the concrete that has been handed over. As a repair method for a crack having a width of about 0.2 mm or more that can be visually observed caused by such cutting, techniques described in Patent Document 1 and Patent Document 2 below are known. In addition, surface modification methods such as the Zipex method, which chemically react with cement and self-repair cracks on the concrete surface, have been proposed.
JP 2002-121901 A Japanese Patent Laid-Open No. 08-260562

  However, according to the conventional crack repairing method as described above, the repair material cannot penetrate into fine cracks (micro cracks) of about 0.01 mm or less in width, which are invisible due to cutting, Therefore, the adhesion strength of the inherited concrete and mortar cannot be increased against such microcracks.

  In addition, microcracks generated by cutting are generated in such a manner that when the aggregate exists on the cutting surface, the aggregate and the paste are separated on the back surface of the aggregate. And the repair material described in the said patent document was not a material with the effect which osmose | permeates such a micro crack and adhere | attaches an aggregate and a paste.

  In addition, the method of repairing cracks by modifying the concrete surface by modifying the concrete surface, such as the Zypex method, has the effect of blocking deterioration factors, but improves the adhesive properties after joining. It was not a thing.

  The present invention has been made in view of the problems as described above, and the technical problem is to repair damage in the vicinity of the cutting surface caused by cutting work performed during repair / reinforcement of a concrete structure. It is an object of the present invention to provide an effective method for repairing fine cracks that are not visible.

  As a means for effectively solving the technical problems described above, a method for repairing a concrete structure according to the present invention includes a synthetic resin solvent and its hardening on a concrete surface that has been cut in a repair or reinforcement work for a concrete structure. A two-component mixed adhesive synthetic resin composition having a viscosity of less than 100 mPa · s / 20 ° C mixed with an agent is applied, and after the required curing time has elapsed, the adhesive synthetic resin composition is coated on the application surface. It is characterized by casting a cement-based joint material. In addition, the cement-type joint material here is concrete or mortar, for example.

  More preferably, in the above method, after the adhesive synthetic resin composition is applied, a sheet is hermetically attached to the concrete surface so as to cover the uncured application surface of the adhesive synthetic resin composition, This sheet is brought into close contact with the application surface by exhausting the sealed space between them.

  According to the method for repairing a concrete structure according to claim 1, the adhesive synthetic resin composition applied to the cutting surface of the concrete structure has a very low viscosity of less than 100 mPa · s / 20 ° C. Can penetrate well into invisible fine cracks of 0.01 mm or less, and as a result, it is possible to increase the adhesion strength with the cement-based joint material.

  Further, according to the method for repairing a concrete structure according to the invention of claim 2, the adhesive synthetic resin composition can be penetrated deeper, and it is difficult to penetrate fine cracks only by coating. However, it can penetrate well and increase the adhesion strength with the cement-based joint material.

  Hereinafter, a preferred embodiment of a method for repairing a concrete structure according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a part of an existing concrete structure, FIG. 2 is a cross-sectional view showing a state in which the surface of the existing concrete structure is cut (suspended), and FIG. 3 is an existing concrete structure FIG. 4 is a cross-sectional view showing a state where the adhesive synthetic resin composition is applied to the cut surface of FIG. 4, FIG. 4 is a cross-sectional view showing a state where the adhesive synthetic resin composition has penetrated into fine cracks in an existing concrete structure, and FIG. These are sectional drawings which show the state which handed over the cement-type joint material to the application surface of the adhesive synthetic resin composition.

  In FIG. 1, reference numeral 1 is an existing concrete structure to be repaired composed of concrete paste 11 and coarse aggregate 12 made of cement and sand, and 11 a is an unhealthy part due to deterioration or damage occurring in the surface layer of the concrete paste 11. It is.

  Prior to the restoration of the concrete structure 1 by the joining of a cement-based joining material (for example, concrete), the unhealthy portion 11a in the surface layer portion of the concrete structure 1 is first formed by a water jet method, a breaker method, or a spiky hammer method. Etc. are removed by performing a cutting process (hanging) by a well-known method. As a result of such a cutting process, the surface layer portion of the concrete structure 1 has fine cracks (hereinafter referred to as microcracks) having a width of about 0.01 mm or less from the cut surface 1a as shown in FIG. 1b occurs innumerably. The microcrack 1b extends in such a way that the coarse aggregate 12 and the concrete paste 11 are separated at the portion where the coarse aggregate 12 is exposed on the cutting surface 1a.

  In the method for repairing a concrete structure according to the present invention, in order to repair such a microcrack 1b, an adhesive synthetic resin composition 2 is applied to the cutting surface 1a as shown in FIG. Adhesive synthetic resin composition 2 is a two-component mixed type with a synthetic resin solvent selected from epoxy, acrylic or urethane and its curing agent, and the viscosity after mixing is 100 mPa · s / 20 ° C. Less than, very low viscosity.

  The viscosity of the adhesive synthetic resin composition 2 can be made less than 100 mPa · s / 20 ° C. by diluting with a solvent such as xylene or adjusting the blending of the curing agent.

  Moreover, the application method of the adhesive synthetic resin composition 2 is appropriately selected depending on the surface shape and part of the repaired portion of the concrete structure 1, such as iron coating, brush coating, roller coating, or spraying.

  As described above, the adhesive synthetic resin composition 2 has an extremely low viscosity of less than 100 mPa · s / 20 ° C. and a small surface tension, so that the wettability is good and the width is 0.01 mm or less invisible microcracks. 1b is well penetrated by capillary action. When the viscosity is 100 mPa · s / 20 ° C. or higher, it is difficult to penetrate the microcrack 1b having a width of 0.01 mm or less.

  After the application of the adhesive synthetic resin composition 2, when a predetermined curing time (for example, about 2 hours) has passed and the required adhesive strength has been developed, the application surface of the adhesive synthetic resin composition 2 is shown in FIG. As shown, cement-based reinforcement 3 such as concrete or mortar is cast over. The cement-based reinforcing material 3 that has been handed over is well joined to the cement-based reinforcing material 3 and is integrated with the concrete structure 1 via the cement-based reinforcing material 3, whereby the concrete structure 1 is repaired and reinforced. The

  Next, FIG. 6 and FIG. 7 show a method for further reliably infiltrating the adhesive synthetic resin composition into the microcrack 1b in the method for repairing a concrete structure according to the present invention. 6 is a cross-sectional view showing a process of exhausting the sealed space between the application surface of the adhesive synthetic resin composition and the sheet, and FIG. 7 is a state in which the sheet is in close contact with the application surface of the adhesive synthetic resin composition by the exhaust. FIG.

  That is, in this case, as shown in FIG. 3 described above, when the adhesive synthetic resin composition 2 is applied to the cutting surface 1a of the concrete structure 1, as shown in FIG. A sheet 4 made of a soft synthetic resin having flexibility is attached so as to cover the cured adhesive synthetic resin composition 2. A gap between the sheet 4 and the concrete structure 1 is eliminated by an appropriate sealing material (not shown). Further, a hole is formed in the sheet 4, and a vacuum pump 6 is connected to the hole via a tube 5.

  Next, by driving the vacuum pump 6 and exhausting the sealed space S inside the sheet 4, as shown in FIG. 7, the sheet 4 is uncured by the atmospheric pressure acting from the outside. The adhesive synthetic resin composition 2 is closely attached to the application surface. And since the residual air in the microcrack 1b is excluded by evacuating the sealed space S in this manner, the adhesive synthetic resin composition 2 can be satisfactorily penetrated into the microcrack 1b.

  Thereafter, the sheet 4, the tube 5 and the vacuum pump 6 are removed, and the cement-based reinforcing material 3 is succeeded as shown in FIG.

Table 1 shows the test results for verifying the effects of the present invention. In this test, Comparative Example 1 is a case where the surface layer portion of the existing concrete structure has no deteriorated portion, so that the concrete is handed over without cutting the surface, and Comparative Example 2 is the surface of the existing concrete structure. After cutting the concrete, the concrete was cast without applying the synthetic resin composition. In Comparative Example 3, after cutting the surface of the existing concrete structure, the conventional epoxy synthetic resin composition was applied. In this example, the concrete was handed over by the method of the present invention, and for each, the adhesion strength between the existing concrete structure and the handed over concrete was measured. is there. The compressive strength of the existing concrete structure (base material) and the cast concrete was about 30 N / mm ² .

  From this test result, in Comparative Example 1 in which cutting was not performed, there was no damage to the concrete, and thus a large tensile strength was obtained. In Comparative Examples 2 and 3, however, due to the occurrence of microcracks due to cutting, the concrete was beaten. It can be seen that the adhesion strength after splicing is ½ or less compared to Comparative Example 1. On the other hand, according to the present invention (Example), it was confirmed that the adhesion strength was increased by 30% or more compared to Comparative Example 2 and Comparative Example 3 by repairing the microcracks.

It is sectional drawing which shows a part of existing concrete structure in the restoration method of the concrete structure which concerns on this invention. It is sectional drawing which shows the state which cut | disconnected (hanging) the surface of the existing concrete structure in the restoration method of the concrete structure which concerns on this invention. It is sectional drawing which shows the state which apply | coated the adhesive synthetic resin composition to the cutting surface of the existing concrete structure in the repair method of the concrete structure which concerns on this invention. In the repair method of the concrete structure which concerns on this invention, it is sectional drawing which shows the state which the adhesive synthetic resin composition osmose | permeated the fine crack of the existing concrete structure. It is sectional drawing which shows the state which handed over the cement-type joint material to the application | coating surface of the adhesive synthetic resin composition in the restoration method of the concrete structure which concerns on this invention. It is sectional drawing which shows the process of exhausting the sealed space between the application surface of an adhesive synthetic resin composition and a sheet | seat in the restoration method of the concrete structure which concerns on this invention. FIG. 7 is a cross-sectional view showing a state in which the sheet is in close contact with the application surface of the adhesive synthetic resin composition by the exhaust shown in FIG. 6 in the method for repairing a concrete structure according to the present invention.

Explanation of symbols

1 Concrete structure 1a Cutting surface 1b Microcracks (fine cracks)
11 Concrete paste 11a Unhealthy part 12 Coarse aggregate 2 Adhesive synthetic resin composition 3 Cement-based reinforcing material 4 Sheet 5 Tube 6 Vacuum pump S Sealed space

Claims (2)

  A two-component mixed adhesive synthetic resin composition with a viscosity of less than 100 mPa · s / 20 ° C, which is obtained by mixing a synthetic resin solvent and its hardener on the concrete surface that has been cut during repair and reinforcement work for concrete structures. A method for repairing a concrete structure, comprising applying a cement-based joint material to a surface to which the adhesive synthetic resin composition is applied after a predetermined curing time has elapsed.   After application of the adhesive synthetic resin composition, a sheet is hermetically attached to the concrete surface so as to cover the uncured application surface of the adhesive synthetic resin composition, and the sealed space between the application surface is exhausted. The method for repairing a concrete structure according to claim 1, wherein the sheet is brought into close contact with the application surface.

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