JP2014156742A - Repair method of concrete structure and repaired concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crack repair method of a concrete structure, easily and inexpensively constructible by coping with a crack caused in the concrete structure even in the case of being not a straight line, and holding waterproofness when the crack is hardly caused again on a construction surface and even when the crack is caused.SOLUTION: In a repair method of a concrete structure of causing a crack on at least a surface, the repair method of the concrete structure comprises: an adhesion insulation layer formation process of providing an adhesion insulation layer for insulating adhesion on the crack and a peripheral surface of the crack; a polymer cement-based waterproof material layer formation process of forming a stress relaxation and waterproof layer by coating a polymer cement-based waterproof material on the adhesion insulation layer and a peripheral surface of the adhesion insulation layer; and a cement mortar layer formation process of forming a cement mortar layer reinforced by a net on the stress relaxation and waterproof layer and a peripheral surface of the stress relaxation and waterproof layer.

Description

  The present invention relates to a method for repairing a cracked concrete structure and a repaired concrete structure.

  In concrete, cracking occurs due to shrinkage due to hardening / drying, expansion / shrinkage due to the presence / absence of solar radiation and repeated wet / dry, or earthquakes and vibrations, and the crack width also changes.

  Thus, as a repair method when a crack occurs in a concrete structure, the public building repair work standard specification (Non-Patent Document 1) includes a resin injection method, a U-cut sealing material filling method, and a seal method. .

  Among these, the resin injection method is a method of injecting epoxy resin into the cracked part, and such methods include automatic low-pressure epoxy resin injection method, manual epoxy resin injection method, mechanical epoxy resin injection method, etc. There is.

  In addition, the U-cut seal construction method uses an electric cutter or the like along the crack to provide a U-shaped groove having a width of about 10 mm and a depth of about 10 to 15 mm. The surface of the groove is about 3 to 5 mm from the concrete surface. This is a method of filling a polymer cement mortar according to the concrete surface after filling the sealing material so shallowly.

  The seal construction method is a construction method in which a seal material is applied to a cracked portion with a putty spatula or the like to a width of about 10 mm and a thickness of about 2 mm, and the surface is finished smoothly.

  These existing technologies have the following problems.

  The resin injection method cannot confirm whether or not the resin has been reliably injected into the cracked part, and even if it can be injected, if stress or movement occurs in the concrete structure thereafter, the same position, or Cracks are likely to occur again at close positions.

  When the U-cut sealing material filling method is used, the water-tightness of the structure can be secured even if stress or movement occurs in the concrete structure after construction, but mortar is applied to the surface of the U-cut sealing material filling method. In this case, the mortar surface is easily cracked or the mortar part is easily peeled off.

  Also, even with the sealing method, even if stress or movement occurs in the concrete structure after treatment, water tightness can be ensured, but since the sealing material remains on the concrete surface, there is not only a problem with aesthetics, Since the sealing material has low weather resistance, it is likely to need to be repaired in a short time. In addition, in order to improve the appearance and weather resistance, polymer cement mortar and finishing material may be applied to the surface after the construction by the seal method, but in this case, cracks may be caused on the surface due to the movement of the concrete structure. May propagate.

  After applying these conventional methods, finish mortar may be applied to the surface of concrete or boards, but there are some cases in which cracks do not propagate from the joints of concrete or boards to the surface of the finish mortar. Have been proposed (Patent Documents 1 to 5).

  These conventional technologies ensure the water-tightness of cracks generated in concrete structures (infiltration of rainwater and prevention of water leakage), and the cracks are covered and do not propagate new cracks on the surface. Therefore, it is a crack repair method that maintains the beauty.

  However, joint-covering occultation tapes (non-clause tapes (trade names), etc.) used in these improved technologies can be applied to straight cracks on smooth surfaces such as joints such as gypsum boards and ALC panels. It is difficult to apply to uneven cracks on the concrete surface or non-linear cracks.

  The following construction methods have been proposed as measures for preventing the propagation of cracks to the surface finish for non-linear cracks that occur in concrete structures. In other words, an undercoat finishing material that exhibits elasticity is applied to the cracked concrete surface, and a reinforcing tape is applied thereon, and the reinforcing tape is impregnated with an adhesive and fixed to increase the rigidity. This is a method of applying a finishing material to (Cited document 6).

  Also, a surface finishing material is applied to the surface of the concrete on a polymer sheet adhesive (polymer cement film waterproofing agent) with a tensile elongation at break of 30% or more and a three-dimensional network fiber sheet. A construction method that suppresses cracking and peeling of the finishing material has been proposed (Cited document 7).

  These technologies are premised on providing a stretchable layer on the entire concrete surface or on at least one structural surface, which requires a large number of man-hours and construction costs, and the former is coated with an undercoat finishing material that exhibits elasticity. At that stage, the position of the crack is not known, and for that purpose it is necessary to apply a wide range of reinforcing tape.

JP 2005-325627 A JP 2004-124534 A JP 2002-227372 A JP 2000-73512 A JP 10-317630 A JP 2002-38727 A JP 2009-97248 A

Public building renovation standard specifications (supervised by the Ministry of Land, Infrastructure, Transport and Tourism Minister's Secretariat Maintenance Department)

  The present invention improves the above-described conventional problems, i.e., the cracks generated in the concrete structure can be dealt with when it is not a straight line, can be easily and inexpensively constructed, and it is difficult for cracks to occur again on the construction surface, And it aims at providing the crack repair method of a concrete structure in which waterproofness is maintained even if it is a case where a crack arises.

  In order to solve the above-mentioned problems, the repair method for a concrete structure of the present invention is the repair method for a concrete structure in which at least the surface is cracked, as described in claim 1, wherein the crack and the surface surrounding the crack are provided. Adhesive insulating layer forming step for providing an adhesive insulating layer to insulate the adhesive, and applying a polymer cement waterproof material on the adhesive insulating layer and the surface around the adhesive insulating layer to form a stress relaxation / waterproof layer A polymer cement-based waterproofing material layer forming step, and a cement mortar layer forming step of forming a cement mortar layer reinforced with a net on the stress relaxation / waterproof layer and a surface around the stress relaxation / waterproof layer. It is the repair method of the concrete structure characterized by this.

Moreover, the method for repairing a concrete structure according to the present invention is the method for repairing a concrete structure according to claim 1, wherein the polymer cement waterproofing material has an elongation rate at room temperature of 30. %, And the tensile strength is 0.5 N / mm ² or more.

  Moreover, the repair method of the concrete structure of this invention is the repair method of the repair method of the concrete structure of Claim 1 or Claim 2 as described in Claim 3, In the repair method of the said stress relaxation and waterproofing layer, It is reinforced by a net.

  Moreover, the repair method of the concrete structure of this invention is the repair method of the concrete structure of any one of Claim 1 thru | or 3 as described in Claim 4, WHEREIN: The said net | network is alkali-proof. It is characterized by being formed of one or more kinds of fibers selected from glass fibers, carbon fibers, aramid fibers, and ultra-high-strength polyethylene fibers, and / or metal wires such as steel wires.

  Moreover, the repair method of the concrete structure of this invention is the repair method of the concrete structure of any one of Claim 1 thru | or 4 as described in Claim 5, In the repair method of the concrete structure, It is characterized in that the crack is substantially centered and the width in the surface direction is in the range of 50 mm or more and 320 mm or less.

  A concrete structure according to the present invention is repaired by the method for repairing a concrete structure according to any one of claims 1 to 5, as defined in claim 6. It is.

  According to the method for repairing a concrete structure of the present invention, an adhesive insulating layer forming step of providing an adhesive insulating layer that insulates adhesion on the crack and the surface around the crack, the adhesive insulating layer and the adhesive insulating layer A polymer cement-based waterproof material layer forming step of forming a stress relaxation / waterproof layer by applying a polymer cement waterproof material on the surrounding surface, and the stress relaxation / waterproof layer and the stress relaxation / waterproof layer Due to the structure having a cement mortar layer forming process that forms a cement mortar layer reinforced with a net on the surface, if the cracks generated in the concrete structure are not straight, the surface of the cracked concrete structure It can be used even when it is not flat, can be easily and inexpensively constructed, it is difficult to crack again on the construction surface, and cracks may have occurred. It can be waterproof achieve the effect referred to be retained.

In addition, the polymer cement-based waterproofing material is provided with a structure having an elongation at room temperature of 30% or more and a tensile strength of 0.5 N / mm ² or more. Even when the width of the lens changes greatly, the movement can be absorbed and the waterproof performance can be more reliably maintained.

  Moreover, the stress relieving and waterproofing layer is reinforced by a net, so that the stress applied to one place can be dispersed and the layer made of the polymer cement waterproofing material can be prevented from breaking.

  Further, the net is formed of one or more kinds of fibers selected from alkali-resistant glass fibers, carbon fibers, aramid fibers, and ultrahigh-strength polyethylene fibers, and / or metal wires such as steel wires. In addition, the tensile strength of the polymer cement mortar can be reinforced more effectively, and the crack resistance can be further improved.

  Moreover, the structure in which the adhesive insulating layer is provided with a width of 50 mm or more and 320 mm or less along the surface portion, with the surface portion of the crack being substantially in the center, prevents the occurrence of high cracking of the present invention. There are advantages that the effect can be obtained with certainty, man-hours can be reduced, and material costs can be reduced as compared with the case of applying to the entire surface.

  Since the concrete structure of the present invention is repaired by the above-described method for repairing a concrete structure, it is difficult for cracks to occur again on the construction surface, and waterproofness is maintained even if cracks occur.

FIG. 1 is a model diagram showing each step of the concrete structure repair method of the present invention.

  In the method for repairing a concrete structure according to the present invention, the surface portion of the cracked concrete structure (FIG. 1 (a) shows the concrete structure 1 and the crack 2 reaching the surface 1a as a model) and the periphery thereof 1. Adhesive insulating layer forming step of providing an adhesive insulating layer (indicated by reference numeral 3 in FIG. 1), polymer cement waterproofing for forming a stress relaxation / waterproof layer (indicated by reference numeral 4 in FIG. 1) A material layer forming step and a cement mortar layer forming step for forming a cement mortar layer (indicated by reference numeral 5 in FIG. 1) are performed in this order.

<1. Adhesive insulating layer forming process>
The adhesive insulating layer formed in the adhesive insulating layer forming step has a width of about 50 mm or more and 320 mm or less along the surface portion of the cracked concrete structure and substantially along the surface portion of the cracked concrete structure (FIG. 1). (B) is provided with the dimension α), so that the high cracking prevention effect of the present invention can be surely obtained, and the man-hours can be reduced and the material cost can be reduced as compared with the case of applying to the entire surface. This is preferable.

  The adhesive insulation layer is formed as a zero span tension so that the stress is not concentrated in one place, and the final stress is generated due to the expansion of cracks in the concrete structure or the occurrence of misalignment. The effect on the cement mortar layer is mitigated, and cracks in the cement mortar layer are generated, thereby preventing the occurrence of water leakage.

  If the width of the adhesive insulation layer is too narrow, the function of the stress relaxation layer will not be exhibited because the distance between the points of action will be narrow, and even if the cracks are slightly expanded or slightly shifted, Cracks may occur in the cement mortar layer, and if it is too wide, the area where the adhesion between the polymer cement waterproof material and the concrete structure is insulated increases, and there is a risk of peeling off. A more preferable width is 50 mm or more and 200 mm or less.

  Any adhesive insulating layer may be used as long as it can prevent penetration of the polymer cement waterproofing material.

  However, in the packing with the adhesive layer provided on one side, such as a curing tape made of polyethylene (such as mask light tape made by Sekisui Chemical Co., Ltd.), various resin tapes, and the other side with releasability Paper adhesive tape, cloth adhesive tape, etc. used can be easily attached to the surface of a concrete structure, making it possible to easily form an adhesive insulating layer, and the thickness is sufficiently thin. This is preferable because it does not hinder the formation of the waterproof layer.

  The polymer cement waterproof material used in the polymer cement waterproof layer forming process has excellent adhesion to concrete and cement mortar, and is highly extensible. Even when cracks occur on the subsequent surface, the effect of maintaining high waterproof performance is obtained.

  As the polymer cement waterproofing material, those generally available can be used. Here, examples of the polymer of the polymer cement waterproof material include polyacrylic acid ester and polyethylene vinyl acetate.

Among such polymer cement waterproofing materials, there is provided a polymer cement waterproofing material having an elongation of 30% or more at normal temperature (20 ° C.) and a tensile strength of 0.5 N / mm ² or more. It is preferable to use it because higher crack resistance can be obtained, and even when cracks occur on the surface after repair, better waterproof properties can be maintained. The elongation rate of the polymer cement waterproof material is more preferably 50% or more, and the tensile strength is 1 N / mm ² or more.

  These polymer cement-based waterproofing materials are applied on the above-mentioned adhesive insulating layer and the surface of the surrounding concrete structure, and dried as necessary to form a stress relaxation / waterproof layer (FIG. 1 (d)). . The stress relaxation / waterproof layer must be continuously provided on the adhesive insulating layer and on the surface of the concrete structure on which the adhesive insulating layer is not formed, and the adhesive insulating layer is formed. The applied part to the surface of the concrete structure that is not (dimension β in FIG. 1C) is 25 mm or more and 225 mm or less, more preferably 50 mm or more and 100 mm or less in the width direction of the stress relaxation / waterproof layer crack, respectively. Is preferred.

  That is, if this width is too narrow, the function of the stress relaxation layer may not be exhibited because the distance between the points of action becomes narrow, and if it is too wide, the labor for forming the stress relaxation / waterproof layer may increase and the material cost may increase. is there.

  The thickness of the stress relaxation / waterproof layer is preferably 1 mm or more and 3 mm or less. If it is too thick, it may be difficult to construct a polymer cement waterproof material that has fluidity during construction, and the material cost will be high. If it is too thin, the function as a stress relaxation layer may not be exhibited. A more preferable thickness is about 2 mm.

  Here, the stress relaxation / waterproof layer is preferably reinforced by a woven fabric or a non-woven fabric. The woven or non-woven fabric used is preferably a woven or non-woven fabric made of vinylon, nylon, polyester, acrylic, polyethylene, or polypropylene.

  The stress relieving and waterproofing layer reinforced with such a woven or non-woven fabric is formed by, for example, overlaying a woven or non-woven fabric on the surface coated with the polymer cement-based waterproof material, and applying the polymer cement-based waterproof material with a roller or brush. It can be formed by applying while impregnating a woven fabric or a non-woven fabric.

  Following the formation of the stress relaxation and waterproof layer, a cement mortar layer forming step is performed. That is, as schematically shown in FIG. 1D, a cement mortar layer 5 reinforced with a net is formed on the stress relaxation / waterproof layer 4 and on the surface 1a of the concrete structure around the stress relaxation / waterproof layer 4. Form.

  Even if cracks of the concrete structure expand or shift beyond the elongation performance of the cement mortar because it is reinforced with the net in this way, the stress is spread within a wide range of the cement mortar layer. Therefore, the occurrence of cracks on the surface after repair is effectively prevented.

  As cement mortar, so-called on-site blended mortar formulated with cement or sand at the construction site or so-called pre-mixed mortar formulated at the manufacturing plant can be used, but it is properly blended to reduce strength and shrinkage. It is preferable to use a pre-prepared mortar whose quality is confirmed. The net used for reinforcement is preferably alkali-resistant, and is formed of one or more kinds of fibers selected from, for example, alkali-resistant glass fibers, carbon fibers, aramid fibers, and ultrahigh-strength polyethylene fibers. Preferably it is. That is, by being reinforced by a net composed of these high Young's modulus fibers, the tensile stress transmitted from the base concrete is transmitted to the fibers of the net, and cracks are suppressed by the tensile strength of the fibers. When a greater tensile stress is applied to the fibers of the net, fine cracks occur in the cement mortar. When cracks are generated in this way, the tensile stress is transmitted to the fibers of the net, and minute cracks are generated at positions slightly away from the cracks. In this way, the propagation of stress by the net prevents a wide range of cracks caused by the concentration of stress in one place, which has conventionally occurred.

  The cement mortar layer reinforced with such a net is, for example, coated with a cement mortar on the surface of the stress relieving and waterproofing layer to a thickness about half the desired thickness of the cement mortar layer reinforced with the net, It can be formed by immediately laminating a net on the cement mortar surface, pressing the net into the cement mortar with a trowel or the like, and then recoating the cement mortar.

  The thickness of the cement mortar layer reinforced with a net is preferably 5 mm or more and 30 mm or less. If it is too thin, the reinforcing effect by the net may not be sufficiently obtained, and if it is too thick, cracks due to self-shrinkage of the cement mortar may occur, and the material cost also increases. A more preferable range is 7 mm or more and 15 mm or less.

  Although the present invention has been described with reference to a preferred embodiment, the method for repairing a concrete structure and the repaired concrete structure according to the present invention are not limited to the configuration of the above embodiment.

  A person skilled in the art can appropriately modify the repair method of a concrete structure of the present invention and the repaired concrete structure according to conventionally known knowledge. Of course, such modifications are still included in the scope of the present invention as long as the method for repairing a concrete structure of the present invention and the structure of the repaired concrete structure are provided.

  For test specimens with polymer cement mortar coated on one side of a concrete block simulating a crack in a concrete structure Specimens with different net types were prepared, and tensile tests were performed on these specimens.

<Specimen creation material>
<Adhesive insulating layer>
Adhesive insulating layer: Mask light tape No. 730 (Sekisui Chemical Co., Ltd., Width: 50 mm, with an adhesive layer provided on one side of a polyethylene tape). The width of the adhesive insulating layer was adjusted by the number of the tapes attached in parallel.

《Stress relieving and waterproofing layer (polymer cement waterproofing material layer)》
Polymer cement waterproofing material: Z-10 (Nippon Kasei Co., Ltd. polyacrylic acid ester waterproofing material. Elongation at 20 ° C .: 103%, tensile strength: 1 N / mm ² (JIS K6301 (vulcanized rubber physical test method ) According to measurement)
Polymer cement reinforced fiber: Non-woven fabric: Z-10 non-woven fabric (manufactured by Nippon Kasei Chemical Co., Ltd. composed of polyester / nylon fiber, basis weight: 50 g / m ² )

《Cement mortar layer》
Glass fiber net: TD5 × 5 (eyes present Electric Glass Co., Ltd. and a alkali-resistant glass fibers basis weight:.. 150g / m ²⁾
3J Internet (. Sakai Sangyo and a alkali-resistant glass fibers basis weight:. 300g / m ²⁾
Cement mortar: NS agri mortar Hi (Nippon Kasei Co., Ltd.)

<Method for preparing specimen>
A ground block (substantially rectangular parallelepiped shape, height: 150 mm, width: 120 mm, length: 600 mm) was cut at the center in the length direction, and the cut surfaces were combined to obtain a test piece. Each of the test pieces (height: 150 mm, length: 600 mm) was repaired using the above materials.

  The repair work consists of (1) presence / absence of a stress relaxation / waterproof layer (stress relaxation / waterproof layer is applied at the center of the test surface), (2) stress relaxation / waterproof layer (polymer cement waterproof layer, thickness). : 2mm), the presence or absence of a net as a reinforcing material (the width of the net used is equal to the width of each stress relaxation and waterproof layer), (3) Adhesive insulation layer (4) Number of layers of reinforcing material used in cement mortar layer (glass fiber net (described as “single”), combined use of glass fiber net and 3J net (“double” Note that the cement mortar layer was applied to the entire construction surface of the test piece, and the reinforcing material was also placed over the entire construction surface). It was.

  After repair work, a total of 12 test pieces are attached to the tensile tester (grip interval: 540 mm) so that tensile stress is applied in the length direction, and the head load is 0.2 mm / min. In addition, the load at the time of cracking (cracking load), the displacement at that time (cracking displacement), and the cracking state on the repaired surface at that time were investigated. In addition, as a waterproof evaluation, a water column having a height of 50 mm is formed on the repair construction surface of each test piece after the tensile test (the repair construction surface is supported horizontally and on the upper surface). After 24 hours, the presence or absence of water leakage on the opposite side of the contact surface of each test piece with water was observed.

  The results of these evaluations are also shown in Table 2 (in the table, “adhesive insulating layer” indicates “surface portion corresponding to the position of the adhesive insulating layer”. Further, in the table, for example, “5 dispersed in the width of the adhesive insulating layer” "Has five cracks dispersed in the width direction of the surface portion corresponding to the adhesive insulating layer position", and "one in the center of the adhesive insulating layer" “One crack occurred at the center of the corresponding surface portion in the width direction” and “two at the boundary portion of the adhesive insulating layer” means “two locations on the surface portion corresponding to the positions in the width direction of the adhesive insulating layer” Each of the cracks occurred "means each).

  Here, the width of the crack generated in the concrete structure increases or decreases due to the temperature stress of the concrete or repeated wet and dry, but the amount of change in the crack width is less than 0.3 mm. For this reason, when the crack occurrence displacement by the tensile test is 0.4 mm or more, “◯” as a high crack suppression effect is obtained, when the crack occurrence displacement is 0.3 mm or more and 0.4 mm or less, “△” indicates that sufficient crack suppression effect is obtained, and “×” indicates that it is insufficient otherwise. Also, regarding waterproofing, sufficient waterproofing is obtained when there is no water leakage. It was evaluated as “◯” as it was, and “x” as it was insufficient otherwise.

  In Table 2, the fact that the cracking load is large means that the stress relaxation effect including the adhesive insulating layer and the tensile stress relaxation effect by the waterproof layer are large, and that the repair work layer has a tensile stress against the tensile stress. It shows that the tensile strength is large.

  In the test piece according to the example, the crack generation load is about 10 kN, whereas in the test piece according to the comparative example, the crack is generated with a low load of about 5 kN.

  In addition, the crack occurrence displacement indicates the maximum possible range that can correspond to the change in the crack width of the ground concrete (concrete structure), and the crack width of the ground concrete was expanded by about 0.5 mm in the test piece according to the example. Even in this case, the occurrence of cracks on the repair work surface is suppressed, whereas the test piece according to the comparative example has cracks on the repair work surface even if it is increased by about 0.1 mm. Yes.

  In addition, it is understood from Table 2 that the test piece according to the present invention has sufficient waterproofness despite the occurrence of cracks on the surface of the repair work surface.

  Moreover, although the curing tape made from polyethylene was used in the above example as the adhesive insulating layer, it is understood that it functions sufficiently.

DESCRIPTION OF SYMBOLS 1 Concrete structure 1a Surface 2 Crack 3 Adhesive insulating layer 4 Stress relaxation and waterproof layer 5 Cement mortar layer

Claims (6)

In a method for repairing a concrete structure having a crack at least on its surface, an adhesive insulating layer forming step of providing an adhesive insulating layer for insulating the crack on the crack and a surface around the crack;
A polymer cement waterproof material layer forming step of forming a stress relaxation and waterproof layer by applying a polymer cement waterproof material on the adhesive insulating layer and a surface around the adhesive insulating layer; and
A method of repairing a concrete structure, comprising: a cement mortar layer forming step of forming a cement mortar layer reinforced with a net on the stress relaxation / waterproof layer and a surface around the stress relaxation / waterproof layer. ^2. The concrete structure according to claim 1, wherein the polymer cement waterproofing material has an extensibility having an elongation at room temperature of 30% or more and a tensile strength of 0.5 N / mm ² or more. Body repair method.   The method for repairing a concrete structure according to claim 1, wherein the stress relaxation / waterproof layer is reinforced by a net.   The net is formed of at least one fiber selected from alkali-resistant glass fiber, carbon fiber, aramid fiber, and ultrahigh-strength polyethylene fiber, and / or copper wire. The method for repairing a concrete structure according to any one of claims 3 to 4.   5. The adhesive bonding layer according to claim 1, wherein the adhesive insulating layer is provided so that the crack is substantially at the center and the width in the surface direction is in a range of 50 mm to 320 mm. Repair method of concrete structure as described in 4.   A repaired concrete structure which is repaired by the method for repairing a concrete structure according to any one of claims 1 to 5.

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