JP2024047213A - Reinforcement method and structure of concrete structure - Google Patents

Abstract

[Problem] To provide a reinforcement method and structure for a concrete structure that can prevent a continuous fiber reinforcement from peeling off from the concrete structure before it reaches its breaking strength. [Solution] A penetrating resin that penetrates into the cement hydrate structure on the surface 102 of a concrete structure that has been subjected to a surface treatment and hardens to form a surface reinforcement layer having a layer thickness of 0.1 to 3.0 mm, has a compressive strength of 50 N/mm2 or more when hardened, a tensile shear strength of 10 N/mm2 or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for one day + 100°C for two hours, and has a viscosity of 100 to 300 mPa·sec at 23°C. The penetrating resin is applied in an amount of 0.5 to 1.5 kg/m2, and a continuous fiber reinforcement 1 is bonded and integrated to the surface 102 of the concrete structure 100 on which the surface reinforcement layer 110A has been formed. [Selected Figure] Figure 7

Description

The present invention relates to a method and structure for reinforcing concrete structures, such as road bridge decks in civil engineering structures such as bridges and elevated roads, by using continuous fiber reinforcement materials to repair and reinforce (hereinafter simply referred to as "reinforcement") concrete structures.

Concrete structures such as road bridge decks in civil engineering structures such as bridges and elevated roads deteriorate or become damaged over many years of use, causing cracks in the concrete deck. For this reason, conventional methods of reinforcement include attaching continuous fiber reinforcement materials, such as fiber-reinforced sheets made of continuous reinforcing fibers such as carbon fiber and aramid fiber, to the surface of the concrete deck with an adhesive (binder).

Patent Document 1, referring to FIG. 12 attached to the present application, discloses a method of reinforcing a structure in which a plurality of continuous fiber-reinforced plastic strands, in which reinforcing fibers are impregnated with a matrix resin and hardened, are aligned in a curtain-like shape in the longitudinal direction and fixed to each other with a strand fixing material, that is, a fiber-reinforced sheet, i.e., a strand sheet 1, is bonded to a surface 102 of a concrete structure 100 with a binder 104 or the like to integrate the strand sheet 1. As an example,
(a) preparing the surface 102 of the concrete structure 100;
(b) applying a joint adhesive 105 to the surface 102 of the concrete structure 100 after the above-mentioned surface treatment, and then pouring an inorganic binder material such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete as a binder 104;
(c) a step of pressing the fiber-reinforced sheet 1 to which a joint adhesive 105 has been applied onto the inorganic bonding material 104 cast in the step (b) before the joint adhesive 105 hardens, thereby adhering the fiber-reinforced sheet 1 to the surface 102 of the concrete structure 100;
(d) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete as a binder 104 onto the surface 102 of the concrete structure 100 to which the fiber-reinforced sheet 1 is adhered;
The document also discloses a method for reinforcing a structure, which comprises applying a primer (not shown in FIG. 12) to the surface 102 of the concrete structure 100 that has been subjected to the surface preparation in the step (a), and performing the step (b) after the primer has hardened.

The method for reinforcing concrete structures and the reinforced structure of concrete structures achieved thereby use continuous fiber reinforcement materials such as fiber reinforced sheets (strand sheets), which eliminate the need for on-site resin impregnation into the fiber bundles that make up the fiber reinforced sheets, and eliminate the risk of poor impregnation. They also have the advantages of using fiber reinforced sheets, such as high work efficiency and the ability to shorten construction time. In addition, when an inorganic bonding material that is considered to be a cement-based material is used as the bonding material, the bond between the concrete structure and the inorganic bonding material can be made extremely strong, and it is possible to prevent the fiber reinforced sheet from peeling off from the cement material before it reaches its breaking strength. In addition, when an inorganic cement-based material is used as the bonding material, the cement member is fire-resistant and does not burn, so there is a great advantage in that the fiber reinforced sheet, which is effective for reinforcement, is protected from fire and can be treated as a non-combustible material.

The inventors have examined whether it is possible to apply the method of reinforcing concrete structures described in Patent Document 1 to concrete structures such as road bridge decks, and further improve the reinforcing effect by preventing the fiber-reinforced sheet from peeling off the cement material before it reaches its breaking strength. As a result of the inventors' research and experiments, it has been found that the reinforcing method described in Patent Document 1 has the following problems.

In other words, in concrete structures such as road bridge decks, the top surface of the concrete deck is usually paved with a paving material 200 such as asphalt, and when reinforcing the top surface of the concrete deck, the paving material 200 is removed from the top surface 102 of the road bridge deck by chipping with a breaker or, if necessary, removing weak parts of the concrete surface with a water jet or the like.

As shown in FIG. 13, the concrete structure 100, whether reinforced or unreinforced concrete, is made of cement, which is the base material of the concrete, and is made by solidifying coarse aggregate (gravel or crushed stone) 100A or fine aggregate (sand or crushed sand) 100B with cement paste (a paste made by adding water to cement, i.e., "cement hydrate") 100C. It is known that the above-mentioned surface preparation work using a breaker on the top surface of the concrete slab causes microcracks of about 0.01 mm in width and about 5 mm in length at the interface between the aggregate and the cement paste in the base material of the concrete. Conventionally, as described above, a primer has been applied to the top surface of the concrete slab as necessary to improve the adhesive strength between the concrete structure and the fiber-reinforced sheet, but the application of the primer is intended to improve the adhesive strength between the concrete structure and the fiber-reinforced sheet by the adhesive (bonding material) and is not intended primarily to penetrate the primer into the microcracks.

On the other hand, in Patent Document 2, for example, in repairing concrete structures such as deck slabs, chipping treatment can cause weak parts such as microcracks and loose stones to appear even in sound concrete, accelerating re-deterioration of the repaired parts, and in order to solve such problems, a method of repairing concrete structures using a thickness increasing method or a cross-section repair method is proposed in which a room temperature curing epoxy resin (low viscosity epoxy resin) with a viscosity of less than 100 mPa·s at 23° C. is applied to the concrete part after removing the deteriorated part. In other words, Patent Document 2 describes that the penetration depth of low viscosity epoxy resin depends on the viscosity, and by lowering the viscosity, it becomes easier to penetrate into cracked parts of concrete and also easier to penetrate into weak parts of concrete, and describes that the viscosity of the low viscosity epoxy resin is less than 100 mPa·s (preferably 10 to 80 mPa·s) at 23° C., and the application amount is 100 to 1000 g/m ² (preferably 200 to 600 g/m ² ).

Furthermore, the invention described in Patent Document 3, which relates to a waterproofing method for concrete decks for road bridges, describes how an epoxy resin adhesive with a viscosity of 2500 mPa·s/20°C or less is applied to a concrete deck and impregnated therein, and then a heated asphalt waterproofing material is applied to the epoxy resin adhesive-applied surface, and the epoxy resin adhesive and asphalt waterproofing material are cured. It also describes that the lower limit of the viscosity of the epoxy resin adhesive is preferably 100 mPa·s/20°C or more, because if the viscosity is too low, the adhesive will penetrate into the cracks in the deck, and the adhesive once filled into the gaps in the cracks will then flow into the depths of the cracks or penetrate into the concrete, creating gaps in the cracks, resulting in a decrease in the waterproofing effect of the epoxy resin adhesive.

In addition, Patent Document 3 describes that the amount of epoxy resin adhesive to be applied is 0.15 to 0.40 kg/ ^m2 , and the penetration depth is 10 mm or more.

JP 2011-208352 A JP 2013-256835 A JP 2008-57119 A

The results of the inventors' research and experiments on the method of reinforcing concrete structures described in Patent Document 1 above revealed the following:

In other words, as described in the above Patent Document 1, by applying a primer to the upper surface 102 of a concrete deck that has been subjected to chipping work using a breaker to remove paving material from the upper surface of the road bridge deck, it is possible to improve the adhesive strength between the concrete structure 100 and the fiber-reinforced sheet 1 by using an adhesive (binder), as described above. However, it was found that the primer does not penetrate into the structure of the porous "cement hydrate" 100C itself. The reason for this is that conventional primers have a viscosity of about 15,000 mPa·sec at 23°C, and due to their high viscosity, they do not penetrate into the aggregates in the porous "cement hydrate" 100C.

It is also known that when the concrete structure 100 is reinforced with continuous fiber reinforcement, the bonded continuous fiber reinforcement may peel off due to the action of load, depending on the condition of the base concrete before reinforcement. Research and experiments by the inventors have shown that in many cases, peeled-off continuous fiber reinforcement occurs due to damage to a very small surface layer of the base concrete.

The inventors conducted further research and experiments and discovered that it is possible to improve the bonding strength between the concrete structure 100 and the continuous fiber reinforcement material 1 by applying a material with a specified viscosity and amount of a penetrating organic material (penetrating resin) to the concrete surface, which will be described in detail later, and which penetrates and hardens into microcracks that occur during chipping, repairing the cracks, and also penetrates into the cement hydrate structure and hardens. ...

On the other hand, Patent Document 2 describes that, as described above, the penetration depth of low-viscosity epoxy resins depends on the viscosity, and that by lowering the viscosity, it becomes easier for the resin to penetrate into cracks in concrete. It also describes that a low-viscosity epoxy resin with a viscosity of less than 100 mPa·s at 23°C can penetrate up to a maximum of 16.8 mm when applied in an amount of 500 g/ ^m2 .

In general, it is understood as common technical knowledge in this field that when a solvent-free low-viscosity epoxy resin (specific gravity about 1.2) is applied to the surface of a concrete structure in an amount of 500 g/ ^m2 , and all of the applied epoxy resin penetrates into the surface of the concrete structure, the calculated average depth is about 0.4 mm. Therefore, it is presumed that the maximum penetration of 16.8 mm in Patent Document 2 describes the maximum partial depth when damage is caused to the surface of the concrete structure by chipping with a breaker. In other words, it is understood that the invention of Patent Document 2 aims to repair the fine cracks (i.e., microcracks) caused by chipping by filling them with a so-called low-viscosity room-temperature curing epoxy resin with a viscosity of less than 100 mPa·s at 23°C in a short time and curing it, thereby repairing the fine cracks, i.e., the weak parts, in a short time. Note that the invention of Patent Document 2 does not mention mechanical properties such as the strength of the epoxy resin. In addition, it is generally known that when concrete structures are heated by direct sunlight in the summer, they can reach temperatures higher than the air temperature, and sufficient performance must be ensured even at that temperature.

As described above, Patent Document 3 describes that the lower limit of the viscosity of the epoxy resin adhesive is preferably 100 mPa·s/20°C or more because if the viscosity is too low, the adhesive will penetrate into the cracks in the deck, and the adhesive once filled into the cracks will then flow into the depths of the cracks or penetrate into the concrete, creating gaps in the cracks, resulting in a decrease in the waterproofing effect of the epoxy resin adhesive. It also describes that the amount of epoxy resin adhesive to be applied is 0.15 to 0.40 kg/m ² , and the penetration depth is 10 mm or more. On the other hand, it is speculated that the upper limit of 2500 mPa·s is the upper limit necessary for the adhesive to penetrate into the cracks in the deck and fill the cracks once. The invention of Patent Document 3 does not mention the mechanical properties of the epoxy resin, such as its strength.

Thus, Patent Documents 2 and 3 do not teach or suggest at all the new findings made by the inventors, namely, that by applying a permeable organic material (permeable resin) having predetermined physical properties including sufficient heat resistance and permeating and hardening into the cement hydrate structure to the concrete surface with a predetermined viscosity and application amount, the material not only penetrates into the microcracks on the deck surface, but also penetrates and hardens into healthy concrete parts where there are no microcracks, forming a continuous and planar surface reinforcement layer of a predetermined thickness (i.e., 0.1 to 3.0 mm) on the concrete surface, and then applying a joint adhesive and solidifying the continuous fiber reinforcement material 1 to the concrete structure 100 with a binder or the like, it is possible to improve the bonding strength between the concrete structure 100 and the continuous fiber reinforcement material 1.

The present invention is based on the novel findings of the inventors described above.

The main object of the present invention is to provide a method and structure for reinforcing a concrete structure that can bond a continuous fiber reinforcement material extremely firmly to the concrete structure and can prevent the continuous fiber reinforcement material from peeling off from the concrete structure before it reaches its breaking strength, even in a heated environment caused by direct sunlight in summer.

Another object of the present invention is to provide a method and structure for reinforcing a concrete structure in which, when an inorganic cement-based binder is used as a binder between a concrete structure and continuous fiber reinforcement, the cement member is fire-resistant and does not burn, protecting the continuous fiber reinforcement, which is effective for reinforcement, from fire and the like, and the composite structure (or structure) can be treated as a non-combustible material, and further, preventing the continuous fiber reinforcement from peeling off from the concrete structure before it reaches its breaking strength.

The above object can be achieved by the method and structure for reinforcing a concrete structure according to the present invention. In summary, according to the first aspect of the present invention, a method for reinforcing a concrete structure includes adhering a continuous fiber reinforcement material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcement material, to a surface of the concrete structure to integrate the continuous fiber reinforcement material with the surface of the concrete structure, the method comprising the steps of:
(a) preparing a surface of the concrete structure;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure prepared in the step (a) at an application amount of 0.5 to 1.5 kg/m2, the resin permeating into microcracks on the surface and hardening, and also permeating into the cement hydrate structure on the surface of the concrete structure where no microcracks have occurred, and hardening to form a surface reinforced layer having a layer thickness of 0.1 to ^3.0 mm, the resin having a compressive strength of 50 N/mm2 or more when hardened, a tensile shear strength of ¹⁰ N/mm2 or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day (i.e., 23°C for 24 hours) + 100°C for ^{2 hours} , and a viscosity of 100 to 300 mPa·sec at 23°C;
(c) applying a plaster adhesive to the surface of the concrete structure on which the surface reinforcement layer is formed, and then pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete as a binder;
(d) a step of pressing the continuous fiber reinforcement material to which a joint adhesive has been applied onto the inorganic bonding material cast in the step (c) before the joint adhesive hardens, thereby adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(e) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
The present invention provides a method for reinforcing a concrete structure, comprising the steps of:

According to the second aspect of the present invention, there is provided a method for reinforcing a concrete structure, comprising adhering and integrating a continuous fiber reinforcing material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcing material onto a surface of the concrete structure, the method comprising the steps of:
(a) subjecting the surface of the structure to a surface treatment;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure prepared in the step (a) at an application amount of 0.5 to 1.5 kg/m2, the resin permeating into microcracks on the surface and into the cement hydrate structure on the surface of the concrete structure where no microcracks have occurred, and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 ^or more when hardened, a tensile shear strength of ¹⁰ N/mm2 or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , the resin having a viscosity of 100 to 300 mPa·sec at 23°C,
(c) applying a plaster adhesive to the surface of the concrete structure on which the surface reinforcement layer is formed, and then pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete as a binder;
(d) applying a joint adhesive onto the inorganic bonding material cast in the (c) step;
(e) a step of pressing the continuous fiber reinforcement material against the surface of the concrete structure before the joint adhesive applied in the step (d) hardens, and adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(f) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
The present invention provides a method for reinforcing a concrete structure, comprising the steps of:

According to a third aspect of the present invention, there is provided a method for reinforcing a concrete structure, comprising adhering and integrating a continuous fiber reinforcing material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcing material onto a surface of the concrete structure, the method comprising the steps of:
(a) subjecting the surface of the structure to a surface treatment;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure prepared in the step (a) at an application amount of 0.5 to 1.5 kg/m2, the resin permeating into microcracks on the surface and into the cement hydrate structure on the surface of the concrete structure where no microcracks have occurred, and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 ^or more when hardened, a tensile shear strength of ¹⁰ N/mm2 or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , the resin having a viscosity of 100 to 300 mPa·sec at 23°C,
(c) a step of pressing the continuous fiber reinforcement material to which a plaster adhesive has been applied onto the surface of the concrete structure on which the surface reinforcement layer has been formed before the plaster adhesive hardens, thereby adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(d) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
The present invention provides a method for reinforcing a concrete structure, comprising the steps of:

According to a fourth aspect of the present invention, there is provided a method for reinforcing a concrete structure, comprising adhering and integrating a continuous fiber reinforcing material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcing material onto a surface of the concrete structure, the method comprising the steps of:
(a) subjecting the surface of the structure to a surface treatment;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure prepared in the step (a) at an application amount of 0.5 to 1.5 kg/m2, the resin permeating into microcracks on the surface and into the cement hydrate structure on the surface of the concrete structure where no microcracks have occurred, and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 ^or more when hardened, a tensile shear strength of ¹⁰ N/mm2 or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , the resin having a viscosity of 100 to 300 mPa·sec at 23°C,
(c) applying a joint adhesive to the surface of the concrete structure on which the surface reinforcement layer is formed;
(d) a step of pressing the continuous fiber reinforcement material against the surface of the concrete structure before the joint adhesive applied in the step (c) hardens, and adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(e) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
The present invention provides a method for reinforcing a concrete structure, comprising the steps of:

According to the first to fourth embodiments of the present invention, the penetrating resin may be a room temperature curing epoxy resin, a vinyl ester resin, an unsaturated polyester resin, an acrylic resin, etc., but preferably a room temperature curing epoxy resin is used.

The fifth aspect of the present invention is a reinforced structure for a concrete structure obtained by any of the above-mentioned methods for reinforcing a concrete structure.

According to the reinforcing method and structure of the present invention, the penetrating resin penetrates not only into microcracks as with conventional primers, but also into the cement hydrate structure on the surface of the concrete structure that has been subjected to the surface treatment, and hardens to form a reinforced layer on the surface, thereby extremely firmly adhering the continuous fiber reinforcement to the concrete structure, and preventing the continuous fiber reinforcement from peeling off from the concrete structure before it reaches its breaking strength. In addition, since the penetrating resin has sufficient heat resistance, it can withstand the heating environment caused by direct sunlight in summer. Furthermore, according to the present invention, when an inorganic bonding material of a cement-based material is used as a bonding material between the concrete structure and the continuous fiber reinforcement, the cement member is fire-resistant and does not burn, so that the continuous fiber reinforcement, which is effective for reinforcement, is protected from fire and the like, and the structure has a great advantage in that it can be treated as a non-combustible material, and furthermore, it is possible to prevent the continuous fiber reinforcement from peeling off from the concrete structure before it reaches its breaking strength.

FIG. 1 is a perspective view showing an embodiment of a continuous fiber reinforcing material that can be used in the reinforcing method and structure of the present invention. 2(a) and (b) are cross-sectional views of fiber-reinforced plastic strands constituting the continuous fiber reinforcement material that can be used in the reinforcing method and structure of the present invention. 3(a) and 3(b) are perspective views showing another embodiment of a continuous fiber reinforcing material that can be used in the structure reinforcing method and structure of the present invention. 4(a) and (b) are diagrams showing another embodiment of the continuous fiber reinforcing material that can be used in the reinforcing method and structure of the present invention. 5(a) and (b) are diagrams showing another embodiment of the continuous fiber reinforcing material that can be used in the reinforcing method and structure of the present invention. 6(a) to (c) are diagrams showing other embodiments of the method for reinforcing a structure and a continuous fiber reinforcing material that can be used in the structure of the present invention. 7(a) to (h) are process diagrams illustrating one embodiment of a method for reinforcing a structure according to the present invention. 8(A) and (B) are flow diagrams illustrating the method for reinforcing a structure according to the present invention, which is illustrated in the process diagrams shown in FIGS. 7(a) to (h). 9(a) to (f) are process diagrams illustrating another embodiment of the method for reinforcing a structure according to the present invention. 10(A) and (B) are flow diagrams illustrating the method for reinforcing a structure according to the present invention, which is illustrated in the process diagrams shown in FIGS. 9(a) to (f). 11(a) and (b) are diagrams explaining the Construction Research Institute-type adhesion test for demonstrating the reinforcement method and structure of the structure of the present invention, where FIG. 11(a) is an oblique view of the adhesion test device, and FIG. 11(b) is a schematic cross-sectional view of an experimental specimen and a steel attachment. FIG. 12 is a schematic diagram showing an example of a reinforced structure obtained by a conventional method for reinforcing a structure. FIG. 13 is a schematic diagram illustrating the structure of a concrete base material in a concrete structure. FIG. 14 is a photograph showing the results of carbon mapping observation of a cross section of a concrete base material in a concrete structure to which a penetrating resin has been applied.

The concrete structure reinforcement method and structure according to the present invention will be described in more detail below with reference to the drawings and examples.

Example (continuous fiber reinforcement)
In the present invention, a concrete structure such as a road bridge deck in a civil engineering structure such as a bridge or an elevated road is reinforced using a continuous fiber reinforcement material, and various forms of continuous fiber reinforcement material can be used as the continuous fiber reinforcement material. Specific examples of the continuous fiber reinforcement material will be described as Specific Examples 1 to 3. However, the form of the continuous fiber reinforcement material used in the present invention is not limited to those shown in these specific examples.

Specific Example 1
An example of a continuous fiber reinforcement 1 used in the method for reinforcing a concrete structure according to the present invention is shown in Figures 1 and 2. In this example, the continuous fiber reinforcement 1 is a fiber-reinforced sheet 1, so-called a strand sheet, in which a plurality of continuous fiber-reinforced plastic wires (i.e., strands) 2 are aligned in a curtain-like shape in the longitudinal direction and the wires 2 are fixed to each other with wire fixing materials 3.

The fiber-reinforced plastic strands 2 are long and thin (thin) in shape, and are made of a large number of continuous reinforcing fibers f oriented in one direction, impregnated with matrix resin R and hardened, and have elasticity. Therefore, the fiber-reinforced sheet 1, which is made of such elastic fiber-reinforced plastic strands 2 arranged in a curtain shape, i.e., in a sheet shape in which the strands 2 are aligned close to each other and spaced apart, has elasticity in the longitudinal direction. For this reason, for example, the long fiber-reinforced sheet 1 can be carried in a rolled-up state with a predetermined radius during transportation, making it extremely portable. In addition, since the fiber-reinforced sheet 1 is made of fiber-reinforced plastic strands 2, there is no need to worry about the orientation of the reinforcing fibers becoming distorted or thread breakage occurring during transportation, as is the case with unimpregnated reinforcing fiber sheets.

To explain further, the thin fiber-reinforced plastic strand 2 can have a generally circular cross-sectional shape with a diameter (d) of 0.5 to 3 mm (Fig. 2(a)), or a generally rectangular cross-sectional shape with a width (w) of 1 to 10 mm and a thickness (t) of 0.1 to 2 mm (Fig. 2(b)). Of course, various other cross-sectional shapes can be used as needed. In addition, in order to improve the adhesive strength during use, it is preferable that the surface of the fiber-reinforced plastic strand 2 is roughened by shot blasting or using a metal brush.

As described above, in the fiber-reinforced sheet 1 that has been aligned in one direction and formed into a blind shape, the individual wires 2 are fixed by the wire fixing material 3, spaced closely from each other by a gap (g) of 0.05 to 3.0 mm. The length (L) and width (W) of the fiber-reinforced sheet 1 thus formed are determined appropriately according to the dimensions and shape of the structure to be reinforced, but for ease of handling, the total width (W) is generally set to 100 mm to 10 m. The length (L) can be made in strips of about 1 to 5 m, or 100 m or more, but it is cut appropriately before use.

It is also possible to manufacture the fiber-reinforced sheet 1 with a length (L) of about 1 to 5 m and a width W of about 1 to 10 m. In this case, the fiber-reinforced plastic strand 2 can be stretched and wound perpendicularly to the fiber-reinforced plastic strand 2, and transported in a rolled-up shape.

To explain further, when carbon fiber is used as the reinforcing fiber f, the fiber-reinforced plastic wire 2 is used by arranging multiple resin-unimpregnated single fiber bundles, each bundle consisting of 6,000 to 24,000 single fibers (carbon fiber monofilaments) f having an average diameter of 7 μm, in parallel in one direction. The reinforcing fiber f is not limited to carbon fiber, and other inorganic fibers such as glass fiber and basalt fiber; metal fibers such as boron fiber, titanium fiber, and steel fiber; and organic fibers such as aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate, polyester, and high-strength polyester; can be used alone or in a hybrid form by mixing multiple types.

The matrix resin R impregnated into the fiber-reinforced plastic strand 2 can be a thermosetting resin or a thermoplastic resin. As a thermosetting resin, room temperature curing or thermosetting epoxy resin, vinyl ester resin, acrylic resin, unsaturated polyester resin, or phenol resin is preferably used. As a thermoplastic resin, epoxy resin, acrylic resin, nylon, vinylon, etc. are preferably used. The amount of resin impregnation is 30 to 70% by weight, and preferably 40 to 60% by weight.

As a method for fixing each wire 2 with a wire fixing material 3, as shown in FIG. 1, for example, a weft thread is used as the wire fixing material 3, and a sheet of wire consisting of multiple wires 2 arranged in one direction like a curtain, i.e., a continuous wire sheet, is driven perpendicular to the wires at a constant interval (P) and woven together. There are no particular restrictions on the driving interval (P) of the weft thread 3, but it is usually selected to be in the range of 10 to 100 mm intervals, taking into consideration the handleability of the produced fiber-reinforced sheet 1.

The weft thread 3 is, for example, a bundle of glass fibers or organic fibers having a diameter of 2 to 50 μm. As the organic fiber, nylon, vinylon, etc. are preferably used.

Another method for fixing each wire 2 in a blind shape is to use a mesh-like support sheet as the wire fixing material 3, as shown in Figure 3(a).

In other words, one or both sides of a sheet of multiple wires 2 that have been pulled together in a blind shape can be supported by a mesh-like support sheet 3 made of glass fibers or organic fibers with a diameter of 2 to 50 μm.

In this case, for example, the surfaces of the warp threads 4 and weft threads 5 constituting the mesh-like support sheet 3, which has a biaxial structure, are pre-impregnated with a low-melting-point thermoplastic resin, and the mesh-like support sheet 3 is laminated on both sides of the blind-like wire sheet and heated and pressurized to weld the warp threads 4 and weft threads 5 of the mesh-like support sheet 3 to the blind-like wire sheet.

In addition to the biaxial configuration, the mesh-like support sheet 3 can be formed by orienting the glass fibers triaxially, or by arranging only the weft threads 5 perpendicular to the wires 2, forming a so-called uniaxial orientation of the glass fibers, and then bonding the multiple wires 2 aligned in the sheet form.

As the thread for the wire fixing material 3, for example, a double-layered composite fiber having a glass fiber core and a low-melting-point heat-fusible polyester core is also preferably used.

As another method for fixing each wire 2 in a curtain shape, as shown in FIG. 3(b), a flexible strip material such as adhesive tape or bonding tape can be used as the wire fixing material 3. The flexible strip material 3 is attached to one or both sides of the multiple fiber-reinforced plastic wires 2 in a direction perpendicular to the longitudinal direction of each fiber-reinforced plastic wire 2 that has been aligned in a curtain shape to form a sheet.

In other words, the flexible strip 3 is made of a pressure-sensitive adhesive tape such as polyvinyl chloride tape, paper tape, cloth tape, or nonwoven fabric tape with a width (w1) of about 2 to 30 mm. These tapes 3 are usually attached perpendicular to the longitudinal direction of each fiber-reinforced plastic strand 2 at intervals (P) of 10 to 100 mm.

Furthermore, the flexible band material 3 can be achieved by thermally fusing a thermoplastic resin such as nylon or EVA resin in a band shape to one or both sides of the wire 2 in a direction perpendicular to the longitudinal direction.

Furthermore, it can also be made into a woven fiber-reinforced sheet using a loom method.

That is, as shown in FIG.
(a) A plurality of continuous fiber-reinforced plastic strands 2 are arranged in parallel as warp threads with a predetermined gap g between them, and auxiliary warp threads 6 are arranged in parallel at a predetermined interval P0 between the parallel fiber-reinforced plastic strands 2, and ears fe are arranged along both side edges.
(b) Weft threads 3 are arranged at a predetermined interval P along the longitudinal direction of the fiber-reinforced plastic strands 2 so as to be located on either side of the sheet-like fiber-reinforced plastic strands 2 formed of a plurality of fiber-reinforced plastic strands 2 arranged in parallel, and the weft threads 3 are woven into the warp threads 2 and auxiliary warp threads 6, thereby fixing the plurality of fiber-reinforced plastic strands 2 arranged in parallel into a sheet shape.
It is produced by:

Furthermore, as shown in FIG.
(a) A plurality of continuous fiber-reinforced plastic strands 2 are arranged in parallel with a predetermined gap g between them as warp threads, and ears fe are arranged along both side edges.
(b) Weaving a weft 3 at a predetermined interval along the longitudinal direction of a plurality of fiber-reinforced plastic strands 2 arranged in parallel to one another to produce a sheet-like woven fabric;
It is produced by:

Example 2
Fig. 5(a) shows another example of the continuous fiber reinforcement 1 used in the method for reinforcing a structure according to the present invention. In this example, the continuous fiber reinforcement 1 can be a sheet-shaped continuous fiber reinforcement material obtained by impregnating a reinforcing fiber sheet 1A (Fig. 5(b)) in which a plurality of continuous reinforcing fibers f are aligned in one direction with a resin R and hardening the resin, that is, a fiber-reinforced plastic sheet (FRP plate) 1.

More specifically, the reinforcing fiber sheet 1A may be configured as shown in FIG. 5(b), in which the reinforcing fiber sheet 1A made of continuous reinforcing fibers f aligned in one direction is held by a wire fixing material 3 such as a mesh-like support sheet. For example, when carbon fibers are used as the reinforcing fibers f, a plurality of resin-unimpregnated single fiber bundles, each bundle consisting of 6,000 to 24,000 single fibers (carbon fiber monofilaments) f having an average diameter of 7 μm, are aligned in parallel in one direction. The fiber basis weight of the carbon fiber sheet 1A is usually 30 to 1,000 g/m ² .

The mesh-like support sheet as the wire fixing material 3 can be configured in the same way as described in the above specific example 1. In other words, the surfaces of the warp threads 4 and weft threads 5 are pre-impregnated with a low-melting-point thermoplastic resin, and the mesh-like support sheet 3 is laminated on one or both sides of the sheet-like arranged reinforced fiber sheet 1A, which is then heated and pressed, so that the warp threads 4 and weft threads 5 of the mesh-like support sheet 3 are welded to the reinforced fiber sheet 1A.

Then, the reinforcing fiber sheet 1A is impregnated with resin R, and the resin is cured to form a sheet-like continuous fiber reinforcement material, i.e., a fiber-reinforced plastic sheet (FRP plate) 1. This fiber-reinforced fiber sheet 1A can be an FRP plate consisting of a single layer or multiple layers with fibers aligned in one or multiple directions, and can have a roughly rectangular cross-sectional shape (Figure 5(a)) with a width (W) of 100 mm to 10 m and a thickness (t) of 0.1 to 100 mm. Of course, various other widths and thicknesses can be used as needed.

In the above-mentioned reinforced fiber sheet 1A, the reinforced fibers f are not limited to carbon fibers, but may be inorganic fibers such as glass fibers and basalt fibers; metal fibers such as boron fibers, titanium fibers and steel fibers; and organic fibers such as aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate, polyester and high-strength polyester; which may be used alone or in a hybrid form by mixing multiple types.

As for the resin R impregnated in the reinforcing fiber sheet 1A, a thermosetting resin or a thermoplastic resin can be used, similar to the matrix resin in the above specific example 1. As for the thermosetting resin, room temperature curing or thermosetting epoxy resin, vinyl ester resin, acrylic resin, unsaturated polyester resin, or phenol resin is preferably used, and as for the thermoplastic resin, epoxy resin, acrylic resin, nylon, vinylon, etc. are preferably used. Also, the fiber volume content (Vf) is 40 to 75%, preferably 50 to 70%.

In this specific example 2, as described above, the continuous fiber reinforcement 1 is described as a sheet-like continuous fiber reinforcement (FRP plate) 1 obtained by impregnating the reinforcing fiber sheet 1A shown in FIG. 5(b) with resin R and hardening the resin. However, a fiber reinforced sheet, so-called strand sheet 1, made by aligning multiple continuous fiber-reinforced plastic strands 2 in the longitudinal direction in a curtain-like shape as shown in the above specific example 1 described with reference to FIG. 1, etc., can also be impregnated with resin R similar to that in the above specific example 2 and hardened to form a sheet-like continuous fiber reinforcement, i.e., an FRP plate. In this case, the fiber volume content (Vf) of the FRP plate 1 is 40 to 75%, preferably 50 to 70%.

Specific Example 3
6(a), (b), and (c) show another example of the continuous fiber reinforcement 1 used in the method for reinforcing a structure according to the present invention. In this example, the continuous fiber reinforcement 1 is a rod-shaped continuous fiber reinforcement material obtained by impregnating a reinforcing fiber rod 1B (FIG. 6(b)) in which a plurality of continuous reinforcing fibers f are aligned in one direction with a resin R and hardening the resin, that is, a fiber-reinforced plastic rod (FRP rod) 1 (FIG. 6(a)). In addition, in order to improve the adhesive strength during use, it is preferable that the surface of the reinforcing fiber rod 1 is roughened by shot blasting or using a metal brush.

The FRP rod 1 can have a generally circular cross-sectional shape with a diameter (D1) of 5 to 30 mm (see FIG. 6(a)), or as shown in FIG. 6(c), a generally rectangular cross-sectional shape with a width (W1) of 5 to 300 mm and a thickness (T1) of 1 to 20 mm. Of course, various other cross-sectional shapes can be used as needed.

The length (L) of the FRP rod 1 thus formed is determined appropriately according to the dimensions and shape of the concrete structure to be reinforced. For ease of handling, the length (L) is generally in the form of a strip of about 1 to 5 m, or 100 m or more, but when in use, it is cut to the appropriate length.

The FRP rods 1 are arranged parallel to each other and aligned closely to the surface 102 of the concrete structure, with a gap of 5 to 500 mm between each, and are fixed in place, depending on the dimensions and shape of the concrete structure 100 to be reinforced.

To explain further, in the FRP rod 1, as explained in the above specific example, when carbon fiber is used as the reinforcing fiber f, for example, multiple resin-unimpregnated single fiber bundles, each bundle consisting of 6,000 to 24,000 single fibers (carbon fiber monofilaments) f with an average diameter of 7 μm, are used by lining up in parallel in one direction. The reinforcing fiber f is not limited to carbon fiber, and other inorganic fibers such as glass fiber and basalt fiber; metal fibers such as boron fiber, titanium fiber, and steel fiber; and organic fibers such as aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate, polyester, and high-strength polyester; can be used alone or in a hybrid form by mixing multiple types.

The matrix resin R impregnated into the FRP rod 1 can be a thermosetting resin or a thermoplastic resin, similar to the matrix resin R described in the above specific examples 1 and 2. As the thermosetting resin, room temperature curing or thermosetting epoxy resin, vinyl ester resin, acrylic resin, unsaturated polyester resin, or phenol resin is preferably used, and as the thermoplastic resin, epoxy resin, acrylic resin, nylon, vinylon, etc. are preferably used. The amount of resin impregnation is 30 to 70% by weight, preferably 40 to 60% by weight.

(Reinforcement method)
First embodiment
Next, a first embodiment of a method and structure for reinforcing concrete 100 according to the present invention will be described with reference to FIGS. 7(a) to 7(h) and FIGS. 8(A) and 8(B).

According to the first embodiment of the present invention, a concrete structure 100 is reinforced using a continuous fiber reinforcement material 1 as described with reference to Examples 1 to 3. In this embodiment, the sheet-like continuous fiber reinforcement material described in Example 1, that is, a fiber-reinforced sheet (strand sheet) 1, is used. That is, in this embodiment, a plurality of fiber-reinforced plastic wires 2 are laid out in a curtain-like pattern in the longitudinal direction, and the fiber-reinforced sheet 1 in which the wires 2 are fixed to each other with a wire fixing material 3 is bonded to the surface of the concrete structure 100 using a bonding material 104 or the like to form an integrated structure.

When reinforcing concrete structures, for components (structures) that are primarily subjected to bending moments and axial forces, the fiber-reinforced plastic wires 2 are adhered so that their direction is roughly aligned with the principal stress direction of the tensile or compressive stress generated by the bending moment, allowing the fiber-reinforced sheet 1 to effectively bear the stress and efficiently improve the load-bearing capacity of the structure.

(First step)
In order to reinforce the reinforced surface (i.e., the bonded surface) 101 of a concrete structure 100, for example in the case of a concrete road bridge deck, the paving material (not shown) applied to the upper surface of the concrete structure (concrete base material) 100 is removed by chipping with a breaker to expose the reinforced surface 101, or, as shown in Figures 7(a) and (b), the weak portion 101a of the reinforced surface 101 of the concrete structure 100 is removed by grinding means 50 such as a disk sander, sand blaster, steel shot blaster, or water jet, and the bonded surface 101 of the structure 100 is subjected to a preliminary treatment so as to form a surface 102 with an appropriate degree of roughness.

(Second step)
A permeable surface reinforcing layer forming material (sometimes called a "permeable resin") 110 is applied to the primed surface 102 (FIG. 7(c)). As the permeable resin 110, room temperature curing epoxy resin, vinyl ester resin, unsaturated polyester resin, or acrylic resin is used, and room temperature curing epoxy resin is preferably used.

Here, the penetrating resin 110 has a compressive strength of 50 N/mm2 ^or more (usually 200 N/ ^mm2 or less) when hardened, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day (i.e., 23°C for 24 hours) + 100°C for 2 hours. The tensile shear strength is 10 N/mm2 or ^more (usually 40 N/ ^mm2 or less), and if the compressive strength is less than 50 N/ ^mm2 or the tensile shear strength is less than 10 N/ ^mm2 , the function of the surface reinforcement layer 110A formed by penetrating into the structure of the "cement hydrate" 100C cannot be fully achieved. In other words, in forming the surface reinforcement layer 110A in the present invention, it is particularly important that the compressive strength of the penetrating resin 110 when hardened is 50 N/ ^mm2 or more. In other words, the compressive strength of the deck concrete that serves as the base material is generally made to be 20 to 40 N/ ^mm2 . Therefore, the penetrating resin 110, which has physical properties equal to or greater than the base material strength, can penetrate into the healthy, undamaged concrete base material, making it possible to form a surface reinforcement layer 110A with sufficient strength.

In addition, if the glass transition temperature (Tg) is less than 50°C when cured under the conditions of room temperature for one day + 100°C for two hours, the permeated resin itself will become rubbery when heated in direct sunlight in the summer, and will not be able to exhibit sufficient adhesion performance. If the Tg value of the permeating resin 110 exceeds 100°C, there is a problem that the cured resin tends to become brittle, and the resin may break when stress is applied to the fiber reinforcement material. Therefore, it is important that the Tg value of the permeating resin 110 is in the range of 50 to 100°C, preferably 60 to 80°C.

The glass transition temperature (Tg) in the present invention is a value determined by differential scanning calorimetry (DSC) based on the JIS K7121 method for measuring the transition temperature of plastics. The measuring device used was a Hitachi High-Tech Science Corporation product (product name: DSC7020).

It is also extremely important that the penetrating resin 110 penetrates and hardens not only into the microcracks in the base concrete caused by carrying out the first step described above, but also into the structure of the "cement hydrate" 100C itself (i.e., the intact, undamaged cement hydrate portion where no microcracks have occurred). For this reason, the viscosity and amount of the penetrating resin 110 applied to the primed surface 102 are extremely important, along with the physical properties when hardened described above.

According to the present invention, the viscosity of the penetrating resin 110 is 100 to 300 mPa·sec at 23°C. The viscosity in the present invention is measured using a B-type viscometer based on JIS K7117-1:1999, and the measuring device used was a "TVB22H type viscometer" (product name) manufactured by Toki Sangyo Co., Ltd.

As mentioned above, the viscosity value of the primer used in the conventional method assuming continuous construction on the upper surface of the deck is about 15,000 mPa·sec. Compared to the viscosity value of this conventional primer, the viscosity value of the penetrating resin 110 according to the present invention, i.e., 100 to 300 mPa·sec at 23°C, is considered to be extremely low. In the present invention, in order to achieve a viscosity of less than 100 mPa·sec at 23°C, a large amount of solvent or diluent must be added, and there are problems such as the volume reduction of the primer due to evaporation and the inability to proceed to the next step until the evaporation time is over. Furthermore, if the viscosity is too low, there is a possibility that problems such as the primer flowing into the depths of the cracks may occur. In addition, if the viscosity exceeds 300 mPa·sec, the penetration performance decreases and the resin does not penetrate into the aggregate part of the base concrete, and the adhesion performance cannot be improved. In other words, if the viscosity exceeds the upper limit of 300 mPa·sec, there will be a problem in that it will not be able to penetrate undamaged (i.e., healthy, with no microcracks) cement hydrate and form a surface hardened layer of 0.1 to 3.0 mm (preferably 0.4 to 1.5 mm).

It is preferable that the penetrating resin 110 has a thixotropic index (TI value) (ratio of viscosity measured at different rotation speeds using a Brookfield viscometer (viscosity at 2 rpm) ÷ (viscosity at 20 rpm)) of about 1.

Furthermore, according to the present invention, the amount of application of the penetrating resin 110 is 0.5 to 1.5 kg/m ² , preferably 0.5 to 1.0 kg/m ² . As described above, conventionally, a primer is applied to a surface that has been subjected to a base treatment as necessary, but compared to the amount of application of a primer (e.g., an epoxy primer) aimed at repairing only microcracks, which is about 0.2 kg/m ² , according to the present invention, the amount of application of the penetrating resin 110 is extremely large. However, if the amount of application is less than 0.5 kg/m ² , it is insufficient to form a surface reinforcing layer for improving adhesion performance over the entire surface of the coating, and if it exceeds 1.5 kg/m ² , a primer puddle is formed, which causes a problem of cracking due to an exothermic reaction.

According to the present invention, by applying the above-mentioned amount of the penetrating resin 110 having the above viscosity to the surface 102 of the concrete structure that has been subjected to the surface treatment, for example, the upper surface 102 of the concrete floor slab, the penetrating resin 110 penetrates not only the microcracks of the base concrete but also the structure of the "cement hydrate" 100C itself, forming a surface hardened layer 110A on the upper surface 102 of the concrete floor slab. The layer thickness (T110A) of the surface hardened layer 110A is 0.1 mm or more, preferably 0.4 mm or more. The upper limit is not particularly limited, but in reality, it is generally 3.0 mm or less, and 1.5 mm or less is preferable. If the thickness of the surface reinforcement layer 110A is less than 0.1 mm, the surface reinforcement layer 110A cannot be expected to increase the adhesive strength with the fiber reinforced sheet 1, as will be described in detail later. Furthermore, even if the thickness (T110A) of the surface reinforcement layer 110A is increased to, for example, about 3.0 mm, the destruction of the base concrete is predominant, so the increase in adhesive strength is not expected to be significant. Furthermore, an increase in the layer thickness (T110A) increases the amount of penetrating resin 110 to be applied, which not only increases material costs and is uneconomical, but also necessitates an increase in reinforcement construction time, which is not desirable. In other words, the layer thickness (T110A) of the surface reinforcement layer 110A is set to 0.1 to 3.0 mm, preferably 0.4 to 1.5 mm.

The surface reinforcement layer 110A can be visually confirmed by mapping the carbon elements derived from the penetrating resin using a scanning electron microscope-energy dispersive X-ray analysis. Figure 14 is a photograph showing the results of carbon mapping observation of a cross section of a concrete base material coated with a penetrating resin as an experimental example of the present invention described later. It can be seen that carbon atoms derived from the penetrating resin are evenly present within the cement hydrate structure at a depth of at least 0.1 mm from the surface and at most 0.4 mm or more, and that the surface reinforcement layer 110A has been formed.

(Third process)
When the penetrating resin 110 applied to the surface 102 of the concrete structure 100 that has been subjected to the surface treatment in the second step (FIG. 7(c)) penetrates into the structure of the "cement hydrate" 100C (and the microcracks present in the surface vicinity region) and hardens, forming a surface reinforcement layer 110A on the upper surface 102 of the concrete structure, the joint adhesive 105 is applied to this surface reinforcement layer 110A (FIG. 7(d)). Next, preferably, before the joint adhesive 105 hardens, the bonding material 104 is cast to a required thickness (T) (FIG. 7(e)). The casting thickness (T) is appropriately set according to the unevenness of the surface of the bonded surface 102 and the thickness of the fiber-reinforced sheet 1, but is generally set to about 2 to 10 mm.

Various resins can be used for the joint adhesive 105, but it is necessary that the glass transition temperature (Tg) when cured under the conditions of room temperature for one day + 100°C for two hours is 50°C or higher. If the glass transition temperature (Tg) is less than 50°C, the joint adhesive 105 will become rubbery when heated in direct sunlight in the summer, and will not be able to exhibit sufficient adhesion performance. If the Tg value of the joint adhesive 105 exceeds 100°C, there is a problem that the cured adhesive tends to become brittle, and the adhesive may break when stress is applied to the fiber reinforcement material. Therefore, it is important that the Tg value of the joint adhesive 105 is in the range of 50 to 100°C, preferably 60 to 80°C.

Specifically, room temperature curing epoxy resin, vinyl ester resin, unsaturated polyester resin, and acrylic resin are preferably used as the jointing adhesive 105 that effectively adheres to the resin-hardened wire surface of the fiber-reinforced plastic wire 2 that constitutes the fiber-reinforced sheet 1. The jointing adhesive 105 is usually applied at 500 to 4000 g/ ^m2 .

The binder 104 is an inorganic binder such as a cement-based material, i.e., cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete.

In this embodiment, the continuous fiber reinforcement 1 used is a fiber reinforced sheet (strand sheet) having the configuration described in the above specific example 1, with the wires 2 having a maximum diameter (d) of 3 mm and a minimum spacing (g) of 0.05 mm. It is preferable that such a fiber reinforced sheet 1 be held on the surface 102 of the concrete structure 100 so that the binder 104 seeps out from between the wires 2, 2 to solidify the fiber reinforced sheet 1. Therefore, when the fiber-reinforced sheet 1 and the binder 104 of the concrete structure 100 are applied (cast) to the surface of the concrete and in an uncured state, there is almost no dripping or sagging even if the casting thickness (T) is 5 mm or more on the surface of the concrete structure 100, and when a fiber-reinforced sheet 1 with a gap (g) of 0.05 mm between the wires 2 and a diameter (d) of 3 mm is applied to the applied surface of the binder 104, the binder 104 passes between the wires 2 and does not sag.

In order to impart a thickening and binding effect to the inorganic binder material (binder 104) and to add bending toughness, a fibrous material, for example, steel fiber or organic fiber such as vinylon fiber, may be mixed into the inorganic binder material.

Specifically, for example, in the case of steel fibers, it is recommended to add steel fibers with a diameter of 0.6 to 1.0 mm and a length of 30 to 100 mm at a ratio of 0.2 to 0.5% (by weight) to the inorganic binding material. In the case of vinylon fibers, it is recommended to add fibers with a diameter of 5 to 20 μm and a length of 4 to 6 mm at a ratio of 0.05 to 2% (by weight) to the inorganic binding material.

In this embodiment, the binder 104 is preferably an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete, whose fluidity falls within the range of 65±15 mm in a mini-slump test, and therefore the binder 104 can also function as an unevenness correction material for the base concrete surface. For this reason, unlike the conventional continuous fiber sheet bonding method, there is no need to smooth the surface using an unevenness correction material before applying adhesive resin, and unevenness correction and bonding to the fiber-reinforced sheet 1 can be performed simultaneously with a single application of the binder, making it extremely efficient.

(Fourth step)
As shown in FIG. 7( f ), a joint adhesive 105 is applied to the fiber reinforced sheet 1 to be bonded to the surface of the structure.

The joint adhesive 105 is the same as that described above, and must be applied evenly to the surface of the fiber-reinforced plastic strands 2 constituting the fiber-reinforced sheet 1. Usually, 500 to 4000 g/m ² of the joint adhesive is applied to the fiber-reinforced sheet 1.

In addition, if a large amount of reinforcement is required, it is possible to adhere multiple layers of fiber-reinforced sheet 1 to the surface of the concrete structure.

(Fifth step)
Next, as shown in FIG. 7(g), the fiber-reinforced sheet 1 to which the joint adhesive 105 has been applied is adhered to the surface of the concrete structure, i.e., onto the bonding material 104 poured onto the surface in the third step, before the joint adhesive 105 hardens.

(Sixth step)
As shown in Fig. 7(h), a binder 104, i.e., the same binder 104 as used in the third step, i.e., an inorganic binder material, is applied to a thickness Ta on the fiber-reinforced sheet 1 bonded to the surface 102 of the concrete structure 100 and smoothed with a rubber spatula or the like. This makes the fiber-reinforced sheet 1 more firmly integrated with the structure 100. The casting thickness (Ta) is appropriately set according to the thickness of the fiber-reinforced sheet 1, but is generally about 2 to 10 mm. At this time, it is advisable to press the fiber-reinforced sheet 1 with a roller or a rubber spatula to vent the air layer at the adhesive interface from the gap g between the reinforced fiber plastic strands 2, 2.

(Seventh step)
Furthermore, when attaching multiple layers of fiber-reinforced sheets 1, it is possible to integrate the multiple layers of fiber-reinforced sheets 1 with the concrete structure 100 by repeating the process of applying (pouring) the binder 104, attaching the fiber-reinforced sheets 1, and applying a top coat of binder 104 as necessary, in the same manner as described above.

In addition, in a concrete structure 100 such as a road bridge deck, the upper surface of the concrete structure 100 reinforced as described above is usually paved with a paving material 200 such as asphalt (see Figure 12).

As described above, according to the first embodiment of the present invention, by carrying out the work steps (steps 1 to 7) of the method for reinforcing a structure of the present invention described with reference to Figures 7(a) to (h), it can be understood that, in essence, a reinforcement method comprising the following steps (a) to (e) is carried out, as shown in the flow diagram of Figure 8(A).

That is, referring to FIG. 8(A), the method for reinforcing a structure according to the present invention is a method for reinforcing a concrete structure in which a continuous fiber reinforcing material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcing material, is bonded to the surface of the concrete structure to be integrated therewith,
(a) preparing a surface of the concrete structure;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure that has been subjected to the surface preparation in the step (a) at an application amount of 0.5 to ^1.5 kg/m2, the resin penetrating into the cement hydrate structure on the surface of the concrete structure where no microcracks have occurred and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 or more when hardened, a tensile shear strength of 10 N/mm2 ^or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , and a viscosity of 100 to 300 mPa·sec at 23°C;
(c) applying a plaster adhesive to the surface of the concrete structure on which the surface reinforcement layer is formed, and then pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete as a binder;
(d) a step of pressing the continuous fiber reinforcement material to which a joint adhesive has been applied onto the inorganic bonding material cast in the step (c) before the joint adhesive hardens, thereby adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(e) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
The present invention relates to a method for reinforcing a concrete structure, comprising the steps of:

In addition, according to the first embodiment of the present invention, the work procedure in the work process of the reinforcement method of the structure of the present invention described with reference to Figures 7(a) to (h) above can be slightly modified to implement the reinforcement form shown in the flow chart in Figure 8(B).

In other words, according to the work steps in Fig. 7(a)-(h) and the flow diagram in Fig. 8(A), in the reinforcement method of the present invention, in the fourth and fifth work steps (Fig. 7(f) and (g)), i.e., in the reinforcement step (d) shown in Fig. 8(A), the fiber-reinforced sheet 1 is coated with the joint adhesive 105, and the fiber-reinforced sheet 1 is pressed against the structure surface to which the bonding material 104 has been applied to adhere. However, as described in the reinforcement steps (d) and (e) in Fig. 8(B), first, in the fourth step (Fig. 7(f)), the joint adhesive 105 is applied to the structure surface, and then, in the fifth step (Fig. 7(g)), the fiber-reinforced sheet 1 to which the joint adhesive 105 has not been applied is pressed against the structure surface to which the joint adhesive 105 has been applied, so that the joint adhesive 105 can be applied to the fiber-reinforced sheet 1 and the fiber-reinforced sheet 1 can be adhered to the structure surface at the same time.

That is, according to the first embodiment of the present invention, it is also possible to carry out the reinforcement embodiment shown in the flow diagram of FIG. 8(B). In this case, the method for reinforcing a structure according to the present invention is a method for reinforcing a concrete structure in which a continuous fiber reinforcement material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcement material, is bonded to the surface of the concrete structure to be integrated therewith, as shown below.
(a) subjecting the surface of the structure to a surface treatment;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure that has been subjected to the surface preparation in the step (a) at an application amount of 0.5 to ^1.5 kg/m2, the resin penetrating into the cement hydrate structure on the surface of the concrete structure where no microcracks have occurred and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 or more when hardened, a tensile shear strength of 10 N/mm2 ^or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , and a viscosity of 100 to 300 mPa·sec at 23°C;
(c) applying a plaster adhesive to the surface of the concrete structure on which the surface reinforcement layer is formed, and then pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete as a binder;
(d) applying a joint adhesive onto the inorganic bonding material cast in the (c) step;
(e) a step of pressing the continuous fiber reinforcement material against the surface of the concrete structure before the joint adhesive applied in the step (d) hardens, and adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(f) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
The method for reinforcing a concrete structure is characterized by comprising the steps of:

As understood above, the joint adhesive 105 used in the reinforcement method of the present invention is applied to the fiber-reinforced sheet 1 or the surface of the structure, and in order to enable good application regardless of the gradient of the construction site, it is preferable that the viscosity is in the range of 100 to 200,000 mPa·sec at 23°C and that the thixotropic index (TI value) (ratio of viscosity measurements at different rotation speeds using a Brookfield viscometer (viscosity at 2 rpm) ÷ (viscosity at 20 rpm)) is in the range of 1 to 8.

In other words, if the viscosity is less than 100 mPa·sec and the TI value is less than 1, it becomes difficult to ensure the thickness due to sagging, etc., which is not preferable. Conversely, if the viscosity is greater than 200,000 mPa·sec and the TI value is greater than 8, workability decreases and filling between the fiber-reinforced sheets is insufficient, which is also not preferable.

In addition, by using an adhesive with a glass transition temperature (Tg) of 50°C or higher when cured at room temperature for one day and 100°C for two hours, sufficient performance can be achieved even when the temperature rises due to exposure to direct sunlight in the summer.

As understood from the above, according to the method for reinforcing a concrete structure of the present invention and the reinforcement structure of a concrete structure achieved thereby, a surface reinforcing layer 110A is formed on the surface 102 of the concrete structure 100, and the continuous fiber reinforcement material 1 is bonded to the concrete structure 100 via a joint adhesive 105, a binder 104, etc., so that the adhesion between the concrete structure 100 and the continuous fiber reinforcement material 1 can be made extremely strong, and it is possible to prevent the continuous fiber reinforcement material 1 from peeling off from the concrete structure (cement matrix) before it reaches its breaking strength. In addition, by using, for example, a fiber reinforced sheet (strand sheet), and more specifically, an FRP sheet and an FRP rod, which will be described later, as the continuous fiber reinforcement material 1, it is not necessary to impregnate the fiber bundles constituting the continuous fiber reinforcement material 1 with resin on site, so there is no risk of impregnation failure, and it has the characteristics of high work efficiency and the possibility of shortening the construction period. Furthermore, when an inorganic cement-based binder is used as the binder 104, the cement component is fire-resistant and does not burn, so there is a major advantage in that the continuous fiber reinforcement material, which is effective for reinforcement, is protected from fire and can be treated as a non-combustible material.

Second Embodiment Next, a second embodiment of the method and structure for reinforcing concrete 100 according to the present invention will be described with reference to FIGS. 9(a) to 9(f) and 10(A) and 10(B).

(First step)
As in the first embodiment described above, in order to reinforce the reinforced surface (i.e., the bonded surface) 101 of a concrete structure 100, for example in the case of a concrete road bridge deck, the paving material (not shown) applied to the upper surface of the concrete structure (concrete base material) 100 is removed by chipping with a breaker to expose the reinforced surface 101, or, as shown in Figures 9(a) and (b), the weak portion 101a of the reinforced surface 101 of the concrete structure 100 is removed by grinding means 50 such as a disk sander, sand blaster, steel shot blaster, or water jet, and the bonded surface 101 of the structure 100 is subjected to a preliminary treatment so as to form a surface 102 having an appropriate roughness.

(Second step)
A surface reinforcing layer forming material (penetrating resin) 110 is applied to the surface 102 that has been subjected to the base treatment (FIG. 9(c)). The penetrating resin 110 is the same as that in the first embodiment, and is applied to the concrete structure surface 102 with the same viscosity and amount. As a result, as shown in FIG. 9(d), the penetrating resin 110 penetrates not only into the microcracks in the base concrete, but also into the structure of the "cement hydrate" 100C itself, and hardens, forming a surface hardened layer 110A on the concrete deck upper surface 102.

(Third process)
As shown in FIG. 9( d ), a joint adhesive 105 similar to that used in the first embodiment is applied to the fiber reinforced sheet 1 .

(Fourth step)
In addition, when the penetrating resin 110 applied to the primed surface 102 of the concrete structure 100 in the second step (FIG. 9(c)) hardens and a surface reinforcement layer 110A is formed on the upper surface 102 of the concrete structure (FIG. 9(d)), as shown in FIG. 9(e), the fiber reinforced sheet 1 to which the jointing adhesive 105 has been applied is pressed against the concrete structure surface 102 on which the surface reinforcement layer 110A has been formed, and adhered to the surface 102 of the concrete structure before the jointing adhesive 105 hardens. The jointing adhesive 105 used is the same as that used in the first embodiment.

The joint adhesive 105 must be applied evenly to the surface of the fiber-reinforced plastic strands 2 constituting the fiber-reinforced sheet 1, and is usually applied at 500 to 4000 g/ ^m2 to the fiber-reinforced sheet 1.

(Fifth step)
Before the joint adhesive 105 applied to the fiber-reinforced sheet 1 hardens, a bonding material 104 is poured to a required thickness (T) on the surface 102 of the concrete structure to which the fiber-reinforced sheet 1 is bonded (FIG. 9(f)). The thickness (T) is set appropriately depending on the unevenness of the surface 102 to be bonded and the thickness of the fiber-reinforced sheet 1, but is generally about 2 to 10 mm. At this time, it is advisable to press the fiber-reinforced sheet 1 with a roller or a rubber spatula so that the air layer at the bonding interface is exhausted from the gap g between the reinforced fiber plastic strands 2, 2.

The binder 104 is an inorganic binder similar to that described in the first embodiment above, such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete.

As explained in the first embodiment above, it is preferable to add a fiber material, such as steel fiber or organic fiber such as vinylon fiber, to the inorganic binder 104 to impart a thickening and binding effect and to add bending toughness.

In addition, according to this embodiment, when the fiber-reinforced sheet 1 is used, an appropriate gap (g) of about 0.05 to 3 mm can be provided between each wire 2, resulting in good breathability. The air between the structure 100 to be reinforced and the fiber-reinforced sheet 1, or, when multiple fiber-reinforced sheets 1 are stacked as described below, the air between the layers of the fiber-reinforced sheets 1, 1, can be easily discharged, making it difficult for floating or swelling to occur.

Furthermore, since a high-viscosity binder 104 is used, the binder 104 can also function as an unevenness correction agent for the concrete surface. Therefore, unlike the conventional continuous fiber sheet bonding method, there is no need to smooth the concrete surface with an unevenness correction agent before applying adhesive resin, and unevenness correction and adhesion to the fiber-reinforced sheet 1 can be performed simultaneously with a single application of binder, making this extremely efficient.

As with conventional continuous fiber sheet bonding methods, a wide sheet-like reinforcing material of about 100 to 1000 mm in width, i.e., fiber-reinforced sheet 1, is used, so it is easy to cover and bond the entire reinforcement surface of the reinforced structure 100. In addition, compared to conventional methods that bond narrow FRP plates of about 50 mm in width, it is possible to provide a wider bonding area, which makes it less likely for the bonding surface to peel off, and provides a high reinforcing effect.

(Sixth step)
Furthermore, when attaching multiple layers of fiber-reinforced sheets 1, the attachment of the fiber-reinforced sheets 1 and the application (pouring) of the binder 104 can be repeated as necessary, as described above, to integrate the multiple layers of fiber-reinforced sheets 1 with the concrete structure 100.

In addition, in a concrete structure 100 such as a road bridge deck, the upper surface of the concrete structure 100 reinforced as described above is usually paved with a paving material 200 such as asphalt (see Figure 12).

As described above, according to the second embodiment of the present invention, by carrying out the work steps (steps 1 to 6) of the method for reinforcing a structure of the present invention described with reference to Figures 9(a) to (f), it can be understood that a reinforcement method comprising the following steps (a) to (d) is carried out, as shown in the flow diagram of Figure 10(A).

That is, referring to FIG. 10(A), the method for reinforcing a structure according to the present invention is a method for reinforcing a concrete structure in which a continuous fiber reinforcing material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcing material, is bonded to the surface of the concrete structure to be integrated therewith,
(a) subjecting the surface of the structure to a surface treatment;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure that has been subjected to the surface preparation in the step (a) at an application amount of 0.5 to ^1.5 kg/m2, the resin penetrating into the cement hydrate structure on the surface of the concrete structure where no microcracks have occurred and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 or more when hardened, a tensile shear strength of 10 N/mm2 ^or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , and a viscosity of 100 to 300 mPa·sec at 23°C;
(c) a step of pressing the continuous fiber reinforcement material to which a plaster adhesive has been applied onto the surface of the concrete structure on which the surface reinforcement layer has been formed before the plaster adhesive hardens, thereby adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(d) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
The present invention relates to a method for reinforcing a concrete structure, comprising the steps of:

In addition, according to the second embodiment of the present invention, the work procedure in the work process of the reinforcement method of the structure of the present invention described with reference to Figures 9(a) to (f) above can be slightly modified to implement the reinforcement form shown in the flow chart in Figure 10(B).

In other words, according to the work steps in Fig. 9(a)-(f) and the flow diagram in Fig. 10(A), in the reinforcement method of the present invention, in the third and fourth steps of the work steps (Fig. 9(d) and (e)), i.e., in the reinforcement step (c) shown in Fig. 10(A), the fiber-reinforced sheet 1 is coated with the splicing adhesive 105 and pressed against the surface of the structure to adhere to it. However, as described in the reinforcement steps (c) and (d) in Fig. 10(B), first, in the reinforcement step (c) shown in the third step (Fig. 9(d)), the splicing adhesive 105 is applied to the surface of the structure, and then, in the fourth step (Fig. 9(e)), the fiber-reinforced sheet 1 is pressed against the surface of the structure to which the splicing adhesive 105 has been applied, so that the fiber-reinforced sheet 1 can be applied with the splicing adhesive 105 and adhered to the surface of the structure at the same time.

That is, according to the second embodiment of the present invention, it is also possible to carry out the reinforcing embodiment shown in the flow chart of FIG. 10(B). In this case, the reinforcing method of the structure of the present invention according to the present invention is a method of reinforcing a concrete structure in which a continuous fiber reinforcing material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcing material, is bonded to the surface of the concrete structure to be integrated therewith, as shown below.
(a) subjecting the surface of the structure to a surface treatment;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure that has been subjected to the surface preparation in the step (a) at an application amount of 0.5 to ^1.5 kg/m2, the resin penetrating into the cement hydrate structure on the surface of the concrete structure where no microcracks have occurred and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 or more when hardened, a tensile shear strength of 10 N/mm2 ^or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , and a viscosity of 100 to 300 mPa·sec at 23°C;
(c) applying a joint adhesive to the surface of the concrete structure on which the surface reinforcement layer is formed;
(d) a step of pressing the continuous fiber reinforcement material against the surface of the concrete structure before the joint adhesive applied in the step (c) hardens, and adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(e) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
The present invention relates to a method for reinforcing a concrete structure, comprising the steps of:

The concrete structure reinforcement method according to the second embodiment and the reinforcement structure of the concrete structure achieved thereby can achieve the same effect as the first embodiment. In other words, as understood above, according to the concrete structure reinforcement method according to the present invention and the reinforcement structure of the concrete structure achieved thereby, a surface reinforcement layer 110A is formed on the surface 102 of the concrete structure 100, and the continuous fiber reinforcement 1 is bonded to the concrete structure 100 via a joint adhesive 105, a binder, etc., so that the adhesion between the concrete structure 100 and the continuous fiber reinforcement 1 can be made extremely strong, and it is possible to prevent the continuous fiber reinforcement 1 from peeling off from the concrete structure (cement matrix) 100 before it reaches its breaking strength, which is an excellent effect. In addition, by using, for example, a fiber reinforced sheet (strand sheet), and more specifically, an FRP sheet and an FRP rod described later as the continuous fiber reinforcement 1, it is not necessary to impregnate the fiber bundles constituting the continuous fiber reinforcement 1 with resin on site, so there is no risk of impregnation failure, and it has the features of high work efficiency and shortening the construction period. Furthermore, when an inorganic cement-based binder is used as the binder 104, the cement component is fire-resistant and does not burn, so there is a major advantage in that the continuous fiber reinforcement material, which is effective for reinforcement, is protected from fire and can be treated as a non-combustible material.

Third Example In the above first and second examples, the method and structure for reinforcing concrete 100 according to the present invention have been described as using the sheet-shaped continuous fiber reinforcement material described in Example 1, i.e., the fiber-reinforced sheet (strand sheet) 1. However, in the present invention, the sheet-shaped continuous fiber reinforcement material described in Examples 2 and 3, i.e., the FRP plate 1, or the rod-shaped continuous fiber reinforcement material, i.e., the FRP rod 1, can also be used as the continuous fiber reinforcement material 1. Even in this case, a similar reinforcement structure can be obtained by carrying out the method for reinforcing concrete 100 according to the steps described in the above first and second examples.

However, when the sheet-shaped continuous fiber reinforcement material described in Example 2, i.e., the FRP plate 1, is used, when the binder is applied in the third step of the first embodiment, etc., the binder does not seep out between the plastic wires 2 of the continuous fiber reinforcement material 1. Also, the rod-shaped continuous fiber reinforcement material described in Example 3, i.e., the FRP rod 1, is arranged and fixed in parallel to each other, spaced apart from each other by a gap of 5 to 500 mm, depending on the size and shape of the concrete structure 100 to be reinforced. However, in the third embodiment, the same effects as those obtained by the method and structure for reinforcing concrete 100 described in the first and second embodiments can be achieved.

Next, the following experiment was conducted to demonstrate the effectiveness of the structure reinforcement method and reinforcement structure of the present invention.

Experimental Example 1 (Construction Research Institute Adhesion Test)
In this experimental example, an evaluation test of the adhesive performance between the concrete structure surface (reinforced surface) 102 and the continuous fiber reinforcement material 1 in a concrete structure 100 reinforced according to the present invention was carried out in accordance with the Construction Research Institute type adhesive test specified in JIS A 6909.

The shape, dimensions, and adhesive test method of the concrete structure test specimen 100T used in this experimental example are shown in Figure 11(a). As shown in Figure 11(a), the test specimen 100T had a length (L0) of 1800 mm, a width (W0) of 900 mm, and a height (H0) of 500 mm.

Next, a room temperature curing epoxy resin ("Penetrating KS Primer" (product name) manufactured by Kashima Road Co., Ltd.) was used as a surface reinforcing layer forming material (penetrating resin) 110 on the base treatment surface 102 of the experimental specimen 100T. The viscosity at 23°C was adjusted to 160 mPa·sec, and the thixotropic index (TI value) (the ratio of the measured viscosity values at different rotation speeds in a B-type viscometer (viscosity at 2 rpm) ÷ (viscosity at 20 rpm)) was adjusted to 1, and then the resin was applied with a roller brush to an application amount of 0.5 kg/ ^m2 .

The penetrating resin (room temperature curing epoxy resin) 110 used had a compressive strength of 119 N/ ^mm2 and a tensile shear strength of 14.9 N/ ^mm2 when cured. In addition, the glass transition temperature (Tg) after curing at room temperature (23°C) for 24 hours plus at 100°C for 2 hours was 54°C.

While the penetrating resin (room temperature curing epoxy resin) 110 used was still uncured, 0.9 kg/m2 of epoxy resin for bonding concrete ("KS Bond" (product name) 121 manufactured by Kashima Road Co., Ltd.) was applied to the surface 102 of the experimental specimen ^100T using a roller brush (coating thickness: approximately 0.7 mm). Next, as shown in Figures 11(a) and (b), a steel attachment (jig) 120 with vertical and horizontal dimensions of (L1) 40 mm x (W1) 40 mm was adhered to the surface 102 of the experimental specimen 100T. The glass transition temperature (Tg) of the epoxy resin for bonding concrete used in the experiment after curing at room temperature (23°C) for 24 hours plus 100°C for 2 hours was 80°C.

Then, the steel attachment 120 was pulled upward with a load Pf to perform an adhesion strength test, and the state of destruction (destruction of the concrete or destruction of the attachment adhesive 121) on the surface of the experimental specimen 100T was observed to evaluate the adhesive performance. The results of the adhesion strength test are shown in Table 1.

In Table 1, experimental examples 1 to 9 show the test results in which a penetrating resin was applied to the surface 102 of the experimental specimen 100T according to the present invention to form a surface hardened layer 110A as described above, and comparative examples 1 to 9 show the test results in which a penetrating resin was not applied to the surface 102 of the experimental specimen 100T, and therefore no surface hardened layer 110A was formed. Note that in this adhesion strength test, the same concrete base material was used for the experimental specimen 100T used in the experimental examples and comparative examples.

The test results confirmed that the test specimens shown in Experimental Examples 1 to 9, in which the surface-hardened layer 110A was formed by applying the penetrating resin 110 to the surface 102 of the test specimen 100T according to the present invention, had a breaking strength 1.16 times higher than the test specimens shown in Comparative Examples 1 to 9, in which the surface 102 of the test specimen 100T did not have the surface-hardened layer 110A.

Experimental Example 2 (Confirmation of Surface Reinforcement Layer)
In this experimental example, samples were taken from the surface of concrete specimens to which the penetrating resin of the embodiment in Experimental Example 1 and the general-purpose epoxy resin for concrete bonding of the comparative example were separately applied, and cross-sectional samples were prepared. The surface reinforcement layer was confirmed by mapping the carbon elements derived from the penetrating resin using a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) at a magnification of 100 times and an acceleration voltage of 15 kV.

As a result, as shown in FIG. 14, it was confirmed that carbon derived from the penetrating resin of the embodiment is evenly present within the hydrate structure excluding the aggregate to a depth of at least 0.1 mm from the surface of the concrete base material, and up to a depth of 0.4 mm or more. It was found that the penetrating resin penetrated into the structure of the concrete hydrate itself, forming a surface reinforcement layer 110A.

1. Continuous fiber reinforcement materials (fiber-reinforced plastic sheets, fiber-reinforced plastic rods)
2 Fiber-reinforced plastic wire 3 Wire fixing material (weft, mesh support sheet, flexible strip)
100 Concrete structure 100A Coarse aggregate 100B Fine aggregate 100C Cement hydrate 104 Binder 105 Joint adhesive 110 Surface reinforcing layer forming material (penetrating resin)
110A Surface reinforcement layer

Claims (7)

A method for reinforcing a concrete structure, comprising adhering and integrating a continuous fiber reinforcement material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcement material onto the surface of the concrete structure,
(a) preparing a surface of the concrete structure;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure that has been subjected to the surface preparation in the step (a) at an application amount of 0.5 to ^1.5 kg/m2, the resin penetrating into the cement hydrate structure of the surface of the concrete structure that does not have microcracks and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 or more when hardened, a tensile shear strength of 10 N/mm2 ^or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , and a viscosity of 100 to 300 mPa·sec at 23°C;
(c) applying a plaster adhesive to the surface of the concrete structure on which the surface reinforcement layer is formed, and then pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete as a binder;
(d) a step of pressing the continuous fiber reinforcement material to which a joint adhesive has been applied onto the inorganic bonding material cast in the step (c) before the joint adhesive hardens, thereby adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(e) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
A method for reinforcing a concrete structure, comprising: A method for reinforcing a concrete structure, comprising adhering and integrating a continuous fiber reinforcement material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcement material onto the surface of the concrete structure,
(a) subjecting the surface of the structure to a surface treatment;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure that has been subjected to the surface preparation in the step (a) at an application amount of 0.5 to ^1.5 kg/m2, the resin penetrating into the cement hydrate structure of the surface of the concrete structure that does not have microcracks and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 or more when hardened, a tensile shear strength of 10 N/mm2 ^or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , and a viscosity of 100 to 300 mPa·sec at 23°C;
(c) applying a plaster adhesive to the surface of the concrete structure on which the surface reinforcement layer is formed, and then pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete as a binder;
(d) applying a joint adhesive onto the inorganic bonding material cast in the (c) step;
(e) a step of pressing the continuous fiber reinforcement material against the surface of the concrete structure before the joint adhesive applied in the step (d) hardens, and adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(f) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
A method for reinforcing a concrete structure, comprising: A method for reinforcing a concrete structure, comprising adhering and integrating a continuous fiber reinforcement material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcement material onto the surface of the concrete structure,
(a) subjecting the surface of the structure to a surface treatment;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure that has been subjected to the surface preparation in the step (a) at an application amount of 0.5 to ^1.5 kg/m2, the resin penetrating into the cement hydrate structure of the surface of the concrete structure that does not have microcracks and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 or more when hardened, a tensile shear strength of 10 N/mm2 ^or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , and a viscosity of 100 to 300 mPa·sec at 23°C;
(c) a step of pressing the continuous fiber reinforcement material to which a plaster adhesive has been applied onto the surface of the concrete structure on which the surface reinforcement layer has been formed before the plaster adhesive hardens, thereby adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(d) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
A method for reinforcing a concrete structure, comprising: A method for reinforcing a concrete structure, comprising adhering and integrating a continuous fiber reinforcement material, which is made by impregnating continuous reinforcing fibers with a matrix resin and hardening the continuous fiber reinforcement material onto the surface of the concrete structure,
(a) subjecting the surface of the structure to a surface treatment;
(b) a step of applying a penetrating resin having a viscosity of 100 to 300 mPa·sec at 23°C to the surface of the concrete structure that has been subjected to the surface preparation in the step (a) at an application amount of 0.5 to ^1.5 kg/m2, the resin penetrating into the cement hydrate structure of the surface of the concrete structure that does not have microcracks and hardening to form a surface reinforced layer having a layer thickness of 0.1 to 3.0 mm, the resin having a compressive strength of 50 N/mm2 or more when hardened, a tensile shear strength of 10 N/mm2 ^or more, and a glass transition temperature (Tg) of 50°C or more when hardened under the conditions of room temperature for 1 day + 100°C for ^{2 hours} , and a viscosity of 100 to 300 mPa·sec at 23°C;
(c) applying a joint adhesive to the surface of the concrete structure on which the surface reinforcement layer is formed;
(d) a step of pressing the continuous fiber reinforcement material against the surface of the concrete structure before the joint adhesive applied in the step (c) hardens, and adhering the continuous fiber reinforcement material to the surface of the concrete structure;
(e) pouring an inorganic binder such as cement mortar, polymer cement mortar, cement paste, polymer cement paste, or concrete onto the surface of the concrete structure to which the continuous fiber reinforcement is adhered;
A method for reinforcing a concrete structure, comprising: The method for reinforcing a concrete structure according to any one of claims 1 to 4, characterized in that the penetrating resin is a room temperature curing epoxy resin, a vinyl ester resin, an unsaturated polyester resin, or an acrylic resin. A reinforced concrete structure obtained by the method for reinforcing a concrete structure according to any one of claims 1 to 4. The reinforcement structure for a concrete structure according to claim 6, characterized in that the penetrating resin is a room temperature curing epoxy resin, a vinyl ester resin, an unsaturated polyester resin, or an acrylic resin.

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