JP6816319B1 - Two-component mixed adhesive for concrete bonding and concrete reinforcement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-component mixed type adhesive for adhering concrete having good characteristics. SOLUTION: In a two-component mixed adhesive for concrete adhesion, which comprises a main agent containing an epoxy resin and a curing agent containing a diamine compound and a polyamine compound, as diamine compounds, a metaxylene diamine derivative and a poly It contains oxypropylene diamine, contains aliphatic polyamines or alicyclic polyamines as polyamine compounds, and does not contain isophorone diamine in the curing agent. By using such a two-component mixed adhesive, the adhesive strength between the existing concrete and the thickened concrete is improved, and when the reinforcing bar is used for casting, the reinforcing property of the reinforcing bar is improved, and good concrete reinforcement is performed. It can be performed. Further, the adhesive strength between the existing concrete and the thickened concrete can be increased without using isophorone diamine, which is a poisonous and deleterious substance, as the curing agent. [Selection diagram] None

Description

The present invention relates to a two-component mixed adhesive for concrete bonding and a concrete reinforcing method.

Concrete bridges have excellent durability and have been used as bridges for highways and rivers. However, for example, in the bridges for highways and rivers constructed during the period of high economic growth, there is a need to compensate for the deterioration even though they were formed by the highest level of technology at that time. In addition, concrete bridges are required to be reinforced with high strength for disaster countermeasures.

As such a method for reinforcing a concrete bridge, there is a method called a floor slab thickening method. In the slab thickening method, the concrete slab is reinforced by cutting the slab of the concrete bridge, placing new concrete on it, and integrating the old and new concrete.

For example, Patent Document 1 describes a coating step of applying a resin adhesive to the surface of a steel slab, and sand on the surface of the steel slab to which the resin adhesive is applied, which is less than or equal to a surface dry saturation state. A concrete construction method including a spraying step of spraying and a casting step of placing concrete on the surface of the steel deck on which the sand is sprayed is disclosed. It is disclosed that such a concrete construction method can easily sufficiently improve the adhesive strength between the steel plate and the concrete.

JP-A-2017-115526

The present inventor is engaged in research and development of an adhesive used in a floor slab thickening method, and is studying a two-component mixed adhesive for concrete bonding and a concrete reinforcing method using the same.

In the research and development process, it is necessary to develop an adhesive that can increase the adhesive strength (reinforcing strength) while reducing poisonous and deleterious substances in the two-component mixed adhesive, and to develop a concrete reinforcement method using it. Faced with.

An object of the present invention is to provide a two-component mixed adhesive capable of increasing adhesive strength (reinforcing strength) while reducing poisonous and deleterious substances.

Another object of the present invention is to provide a concrete reinforcing method capable of increasing the adhesive strength (reinforcing strength) while reducing the number of poisonous and deleterious substances used.

A brief outline of the typical inventions disclosed in the present application is as follows.

[1] The two-component mixed adhesive for concrete adhesion disclosed in the present application has a main agent and a curing agent, the main agent contains an epoxy resin, and the curing agent is a diamine-based compound and a polyamine-based adhesive. Includes with compounds. The diamine-based compound contains a metaxylene diamine derivative and a polyoxypropylene diamine, the polyamine-based compound contains an aliphatic polyamine or an alicyclic polyamine, and the curing agent does not contain isophorone diamine.

[2] The concrete reinforcing method disclosed in the present application includes (a) a step of adjusting an adhesive by mixing a main agent and a curing agent, (b) a step of applying the adhesive to the first concrete, and (c). ) It has a step of thickening the second concrete on the first concrete. The main agent contains an epoxy resin, and the curing agent contains a diamine-based compound and a polyamine-based compound. The diamine-based compound contains a metaxylene diamine derivative and a polyoxypropylene diamine, the polyamine-based compound contains an aliphatic polyamine or an alicyclic polyamine, and the curing agent does not contain isophorone diamine.

According to the present invention, in a two-component mixed adhesive, it is possible to increase the adhesive strength (reinforcing strength) while reducing poisonous and deleterious substances. Further, in the concrete reinforcing method, the adhesive strength (reinforcing strength) can be increased while reducing the poisonous and deleterious substances used.

(Embodiment 1)
The present embodiment will be described below with reference to the drawings. In the following description, A to B shall indicate A or more and B or less.

The adhesive of the present embodiment is a two-component mixed adhesive for adhering concrete, and has a main agent (first liquid) and a curing agent (second liquid). Here, in the present specification, the two-component mixed type adhesive shall include both a state before and after mixing the main agent and the curing agent.

(Main agent)
An epoxy resin can be used as the main agent. As the epoxy resin, for example, bisphenol A type liquid epoxy resin, bisphenol F type liquid epoxy resin, bisphenol AD type liquid epoxy resin, novolac type liquid epoxy resin, aliphatic epoxy resin, glycidylamine type epoxy resin and the like can be used. it can. Above all, it is preferable to use a mixture of bisphenol A type liquid epoxy resin and bisphenol F type liquid epoxy resin.

By adding the bisphenol F type liquid epoxy resin to the bisphenol A type liquid epoxy resin, the viscosity can be lowered and the amount of the diluent used can be reduced.

The ratio of the epoxy resin is preferably about 30 to 50% by mass with respect to the total amount of the adhesive after mixing the main agent and the curing agent. Specifically, the bisphenol A type liquid epoxy resin is about 20 to 30% by mass, and the bisphenol F type liquid epoxy resin is 10 to 20% by mass with respect to the total amount of the adhesive after mixing the main agent and the curing agent. It is preferable to set the degree.

A diluent may be added as the main agent. Diluents are used to control the viscosity, as described above. As the diluent, it is preferable to use a mono or diglycidyl ether-based reactive diluent. As such a reactive diluent, 1,6-hexanediol mono, diglycidyl ether, alkyl glycidyl ether and the like can be used. Among them, 1,6-hexanediol diglycidyl ether is a bifunctional type diluent, and can suppress deterioration of resin performance as compared with the monofunctional type. In addition, it has low toxicity and low volatility, and is preferable for use as a diluent. The ratio of the diluent is preferably about 5 to 15% by mass with respect to the total amount of the main agent.

A filler may be added as the main agent. The filler is used, for example, to improve the strength and durability of the adhesive layer. As the filler, for example, calcium carbonate, barium sulfate, silica, clay, talc and the like can be used. Among them, calcium carbonate is suitable for use as a filler because it has a high whiteness and is excellent as an extender pigment, and it has been confirmed that the particle size-adjusted product suppresses deterioration of the cured physical properties. The ratio of the filler is preferably about 40 to 60% by mass with respect to the total amount of the main agent. When a large amount (20% or more) of the filler is mixed in the resin, it is necessary to be concerned about sedimentation and aggregation. This time, in particular, calcium carbonate particles that have been specially treated are used to prevent agglutination so that the particles electrically repel each other. As a special treatment, a fatty acid treatment or the like can be applied. Among the fatty acid treatments, it is preferable to perform saturated fatty acid treatments such as stearic acid (C ₁₈ ) treatment, palmitic acid (C ₁₆ ) treatment, and lauric acid (C ₁₂ ) treatment.

Other additives may be added as the main agent. Examples of other additives include coupling agents, antifoaming agents, thickeners, pigments and the like. As the coupling agent, it is preferable to use one having a surface modification function on the construction surface. For example, a silane coupling agent, particularly γ-glycidoxypropyltrimethoxysilane having an epoxide end, is bonded to an epoxy resin. It is effective for the adhesiveness of the agent. Defoamers are hydrocarbon fats and oils, most of which are colorless, odorless and transparent at room temperature. Fumed silica is effective as a thickener. Fumed silica is divided into hydrophilic type and hydrophobic type. In the hydrophilic type, the hydroxyl group of silanol (R-Si-OH) forms a hydrogen bond with the hydroxyl group in the epoxy resin, which is useful for thickening the system. A hydrophobic type having a repeating group of a siloxane bond (-Si-O-Si) in its structure has a high effect of thickening. The ratio of the other additives is preferably less than 1% by mass with respect to the total amount of the main agent.

(Hardener)
As the curing agent, an amine compound can be used. Here, in the present embodiment, a mixture of a diamine compound and a polyamine compound is used as the curing agent. In the present specification, the polyamine-based compound refers to a compound containing three or more amino groups.

As the diamine compound, it is preferable to use a methylylenediamine derivative and polyoxypropylene diamine.

As the m-xylylenediamine derivative, for example, a phenol formalin reaction product, that is, a Mannich reaction product or the like can be used. Among them, the phenol-formalin reaction product of m-xylylenediamine is suitable for use because it exhibits low-temperature curability and chemical resistance due to the Mannich base.

The phenol-formalin reaction of m-xylylenediamine can be shown as follows (Chemical Formula 1).

In addition, R1-NH-R2 is, for example, m-xylylenediamine, R3CH = O is, for example, formaldehyde, and the compound in parentheses is, for example, phenol. Further, in the above (Chemical formula 1), an auxiliary reaction with various additives may occur. Moreover, in the case of addition of phenol, a Betti reaction may occur as an auxiliary reaction.

The ratio of the meta-xylylenediamine derivative is preferably about 20 to 30% by mass with respect to the total amount of the curing agent. The ratio of polyoxypropylene diamine is preferably about 20 to 30% by mass with respect to the total amount of the curing agent.

Further, as the polyamine-based compound, it is preferable to use an aliphatic polyamine or an alicyclic polyamine. The ratio of the polyamine compound is preferably about 20 to 30% by mass with respect to the total amount of the curing agent. The polyamine-based compound may be a modified product.

In order to obtain high adhesion, stability, and high mechanical strength in an epoxy to amine cured product, inexpensive and high-performance compounds such as m-xylylenediamine and isophoronediamine have been widely used in the past. In particular, the above-mentioned two compounds were excellent and were effective means for modifying the cured product. However, because it is widely used, it is widely known for its toxicity and danger, and it has been designated as a poisonous and deleterious substance.

The phenol-formalin reactant of m-xylylenediamine has not been designated as a poisonous and deleterious substance.

As described above, by using the m-xylylenediamine derivative and the polyoxypropylene diamine, the adhesive strength can be increased without using the poisonous and deleterious substance isophorone diamine.

As a curing agent, a curing accelerator may be added. As the curing accelerator, a phenolic compound, a tertiary amine or the like can be used. As the phenolic compound, for example, p-tert-butylphenol and the like can be used. Phenol and cresol, which have been used conventionally, are also inexpensive and have a high curing promoting effect, but they are poisonous and deleterious substances and are excluded from the safety concept of resin design. As the tertiary amine, for example, 1,3-bis (aminomethyl) cyclohexane, 3- (aminomethyl) benzylamine and the like can be used. The ratio of the curing accelerator is preferably about 10 to 25% by mass with respect to the total amount of the curing agent.

A diluent may be added as the main agent. As the diluent, the same diluent as that used for the main agent can be used.

Other additives may be added as the curing agent. Examples of other additives include dyes and the like. As the dye, for example, an azo dye can be used. The ratio of the other additives is preferably less than 0.5% by mass with respect to the total amount of the main agent. The reasons for blending the dye to color the adhesive are as follows. When the adhesive is applied to the base concrete, which is standard in white, it is easy and effective to visually check the shade of the colored adhesive in order to control the uniformity of the application amount. With colorless and transparent or white, it is difficult to visually control the uniformity (shading) of the adhesive application.

The mixing ratio of the main agent and the curing agent is preferably 10: 1 to 10: 3 in terms of weight ratio.

(Concrete reinforcement method)
Next, a concrete reinforcing method using an adhesive (two-component mixed type adhesive) in which the main agent and the curing agent are mixed will be described.

st1) The main agent and the curing agent are mixed in the above blending ratio to adjust the adhesive.

st2) The above adhesive is applied to the existing concrete. As the coating method, for example, a spray coating method can be used. The brittle layer on the surface of the existing concrete may be peeled off in advance, and then the adhesive may be applied.

st3) Next, thickened concrete is placed. The thickened concrete is placed before the adhesive is cured. For example, it is preferable to cast thickened concrete within 90 minutes (spring / autumn type, base temperature 20 ° C.) after applying the adhesive.

In addition, after placing the grid-like reinforcing bars on the existing concrete, the thickened concrete may be placed.

(Example 1)
Thickened concrete was cast using the main agent and the curing agent of the components shown in Table 1. Specifically, the main agent and the curing agent shown in Table 1 are mixed at a weight ratio of 10: 2, and immediately after applying with a brush onto a concrete material measuring 30 cm × 30 cm and having a thickness of 10 cm, the thickened concrete is thickened. It was cast at 5 cm and left at room temperature (23 ° C.) for 3 days to prepare a sample.

The adhesion strength at the interface between the concrete material and the thickened concrete was tested. As a test, a test was conducted in accordance with the test method 434-2010 of the structure construction management procedure (standard of East, Central and West Nippon Expressway Company). As a result of the test, the adhesion strength at the interface between the concrete material (corresponding to the existing concrete) and the thickened concrete was 2.0 N / mm2 or more. As a result, it was found that the standard that the adhesion strength is 1.0 N / mm2 or more is satisfied.

(Example 2)
A rust preventive test was conducted on an adhesive in which the main agent and the curing agent of the components shown in Table 1 were mixed. Specifically, the main agent and the curing agent shown in Table 1 were mixed at a weight ratio of 10: 2 to obtain an adhesive. As a test, the test method stipulated in the performance verification standard for reinforced concrete rust prevention in the structure construction management guidelines (standards of East, Central and West Japan Expressway Co., Ltd.) (Quality of reinforced concrete repair proof material of the Architectural Institute of Japan) The test was conducted in accordance with the standard (draft).

It was found that the protection rates of the treated portion and the untreated portion were 50% or more and -10% or more, respectively, and satisfied the standard values.

In this way, by placing the thickened concrete using the adhesive of the present embodiment, the adhesive strength between the existing concrete and the thickened concrete is improved, and when the reinforcing bar is used for the placing, the reinforcing bar is used. It was found that it is possible to improve the anti-corrosion property and perform good concrete reinforcement.

In addition, the adhesive shown in Table 1 does not contain isophorone diamine, which is a poisonous and deleterious substance. The content of isophorone diamine is less than 1% by mass with respect to the total amount of the curing agent. The content of isophorone diamine is less than 1% by mass with respect to the total amount of the mixed adhesive after mixing the main agent and the curing agent.

Further, although the adhesive shown in Table 1 contains methoxylendiamine as a residue of the phenol formalin reaction, the content thereof is less than 8% by mass with respect to the total amount of the curing agent, and the main agent and the curing agent are used. It is less than 8% by mass based on the total amount of the mixed adhesive after mixing. The amount of m-xylylenediamine contained in this way is acceptable. As long as it is within the permissible range, it may contain metaxylylenediamine as an additive. The content of m-xylylenediamine is less than 8% by mass, more preferably less than 6% by mass, still more preferably less than 1% by mass, based on the total amount of the mixed adhesive after mixing the main agent and the curing agent.

(Embodiment 2)
In the present embodiment, the results of studies on isophorone diamine substitutes examined by the present inventors will be described in detail.

In designing the curing agent, the compounds shown in Table 2 were considered as the main components. MXDA (methoxylylenediamine: threshold <8%) and IPDA (isophorone diamine: threshold <6%) are poisonous and deleterious substances, but MXDA (methoxylylenediamine) is up to 8% and IPDA (isophoronediamine) is 6. If the content is up to%, it is acceptable, and the past results are very good, so it was included in the study.

In addition, aromatic amines form rigid and excellent cured products of phenyldiamines, but phenyldiamines are not poisonous and deleterious substances by themselves, but are suspected to be carcinogenic and deviate from the design concept. In addition, aromatic amines are often solid and are melted and mixed with other amines, but the viscosity target (23 ° C) of the curing agent is lower than that of the main agent, and it cannot be used extensively, so it was excluded from the main components. .. Since the main agent had a compounding viscosity target (23 ° C.), the temporary composition (see the main agent: component / content in Table 1) was determined before the curing agent. The formulation of the curing agent was examined according to this main agent.

Table 2 lists the amine curing agents that react at room temperature and have a proven track record in past approximation applications and other applications.

The curing agent was adjusted using the components shown in Table 2 above, and thickened concrete was cast in the same manner as in Example 1. Specifically, the main agent shown in Table 1 and the curing agent using the components shown in Table 2 were mixed at a weight ratio of 10: 2 and applied with a brush on a concrete material measuring 30 cm × 30 cm and having a thickness of 10 cm. Immediately after that, thickened concrete was cast to a thickness of 5 cm and left (cured) at room temperature (23 ° C.) for several days to prepare a sample.

For the test method of the sample (main agent-reactive cured product of curing agent), refer to the anchor resin standard (JSCE541) of the Japan Civil Engineering Society, and the property target is East Nippon Expressway Co., Ltd. and Central Nippon Expressway Co., Ltd. -The structure construction management procedure of West Nippon Expressway Co., Ltd. Table 3-10-1 The epoxy resin standard value (example) of the injection method was referred to. Table 3 shows test items, test methods, test conditions, and standards.

In addition, various tests shown in Table 3 and the test of NEXCO test method 434 were performed on Examples A to C and Comparative Examples A and B shown below. The results are shown in Tables 4 and 5.

(Comparative Example A)
Among the curing agents shown in Table 1, the metaxylylenediamine derivative was replaced with an alicyclic amine (norbornane diamine: NBDA), and thickened concrete was cast in the same manner as in Example 1, and the tests shown in Table 5 were performed. .. In the sample using the alicyclic amine (norbornane diamine: NBDA), the sample broke under repeated tensile load of 4.8 million times, and the subsequent adhesion strength test could not be performed. It is presumed that the above results were obtained because the sample using the alicyclic amine (norbornane diamine: NBDA) was hard and rigid but had insufficient toughness.

(Comparative Example B)
Among the curing agents shown in Table 1, the metaxylylenediamine derivative was replaced with a modified polyamine (amine adduct type, amine-epoxy adduct), and thickened concrete was cast in the same manner as in Example 1, and the test shown in Table 5 was performed. went. In the sample using the modified polyamine (amine adduct type, amine-epoxy adduct), there was no deformation under repeated tensile load of 4.8 million times, but the test result of the subsequent adhesion strength was 0.6 N / mm ² It was below the target value of 1.0 N / mm ² . Amine adduct-type modified polyamines were flexible and had high shock absorption capacity, but seemed too soft as an adhesive to adhere concrete to concrete. Also, the adhesion to the wet surface was poor.

(Example A)
As in the case of the curing agent shown in Table 1, 20 to 30% by mass of the metaxylylenediamine derivative was used with respect to the above Comparative Examples A and B with respect to the total amount of the curing agent, and thickened concrete was cast in the same manner as in Example 1. When the tests shown in Table 5 were performed, there was no deformation under repeated tensile loads of 4.8 million times, and the test result of the subsequent adhesion strength was 2.0 N / mm ² , which was the target value. It was well above a certain 1.0 N / mm ² .

(Example B)
Further, when the metaxylylenediamine derivative was used in an amount of 15% by mass based on the total amount of the curing agent, thickened concrete was cast in the same manner as in Example 1, and the test shown in Table 5 was performed, the tension was repeated 4.8 million times. There was no deformation under load, and the test result of the subsequent adhesion strength was 1.2 N / mm ² , which exceeded the target value of 1.0 N / mm ² , but was 480 from the case of Example A. Adhesive strength decreased after repeated tensile loading 10,000 times. In addition, when the adhesion strength after repeated tensile loading of 4.8 million times was performed using a plurality of samples, the variation was large, and the average value cleared the target value of 1.0 N / mm ² , but some of them were found. , It was confirmed that the value was slightly lower than the target value of 1.0 N / mm ² .

(Example C)
Further, when the metaxylylenediamine derivative was used in an amount of 35% by mass based on the total amount of the curing agent, thickened concrete was cast in the same manner as in Example 1, and the test shown in Table 5 was performed, the tension was repeated 4.8 million times. and without Deformation in load, and the test results of the subsequent adhesive strength is 1.9 N / mm ^2, it was sufficiently above the 1.0 N / mm ² which is the target value. However, since this sample tended to be hard, when the impact strength was tested, it was found that the impact strength was lower than that of Example A. As described above, it was confirmed that the toughness of this sample tends to be unstable because it is hard.

(Other comparative examples)
In the above Comparative Examples A and B, the case where NBDA and amine-epoxy adduct were used in Table 2 was described in detail, but sufficient characteristics were obtained even when other materials (excluding MXDA and IPDA) were used. No one was obtained, which was better than that of Example A. Further, when MXDA and IPDA were used, although the characteristics were good, the respective contents could not be less than 8% by mass and less than 6% by mass with respect to the total amount of the curing agent.

(Summary)
As described above, according to the curing agent of the above example, the poisonous and deleterious substances isophorone diamine and methoxylendiamine can be reduced as much as possible, and the adhesive strength can be increased. Further, by setting the content of the m-xylylenediamine derivative with respect to the total amount of the curing agent to 15 to 35% by mass, more preferably 20 to 30% by mass, the characteristics can be further improved.

(Embodiment 3)
For example, the main agent and the curing agent shown in Table 1 can be applied to each season (spring, summer, autumn, winter). Since the viscosities and reaction rates of the main agent and the curing agent change depending on the season, the reaction rate may be optimized by adjusting the amount of the curing accelerator added depending on the season, for example.

For example, regarding p-tert-butylphenol (10 to 20%), which is a curing accelerator shown in Table 1, the content of p-tert-butylphenol (10 to 20%) is 3 to 7% as a spring-autumn type curing agent, and 3 to 7% as a summer type curing agent. The content may be 0 to 2%, and as a winter-type curing agent, the content may be 14 to 20%.

Further, 2,4,6 trisdimethylamine may be used as a curing accelerator.

Since the curing accelerator does not significantly affect the final main structure of the cured product, the final performance of the cured product depends on the type of seasonal product even if the addition amount (content) is adjusted according to the season as described above. Not done.

Further, in the spring-autumn type two-component mixed type adhesive, the suitable operating temperature is about 10 to 30 ° C., and in the summer type, it can be applied even if the surface temperature of the existing concrete becomes 40 ° C. or higher. A suitable operating temperature is about 25 to 45 ° C. Further, in the winter type, it can be applied even if the surface temperature of the existing concrete is 10 ° C. or lower, and the preferable operating temperature is about 5 to 20 ° C.

(Embodiment 4)
For example, in Table 1, a two-component mixed adhesive composed of a main agent and a curing agent has been described, but a three-component adhesive consisting of a main agent, a curing agent and a diluent may be used.

As the diluent, alcohols, specifically ethanol, can be used. Alcohols have low compatibility with epoxy resins, but have good compatibility with curing agents and can be used as diluents. Such diluents are less toxic and are more useful than, for example, using organic solvents such as toluene and xylene.

For example, in winter, when the viscosity of the main agent or curing agent becomes high, the viscosity of the adhesive can be reduced by using a diluent, and the workability can be improved by reducing the viscosity and mechanical construction (spraying). Can be improved.

The invention made by the present inventor has been specifically described above based on the embodiments and examples, but the present invention is not limited to the above embodiments and examples and does not deviate from the gist thereof. Needless to say, it can be changed in various ways.

Claims (10)

It has a main agent and a curing agent,
The main agent contains an epoxy resin and contains
The curing agent contains a diamine-based compound and a polyamine-based compound.
The diamine-based compound contains a meta-xylylenediamine derivative and polyoxypropylene diamine.
The polyamine-based compound contains an aliphatic polyamine or an alicyclic polyamine.
A two-component mixed adhesive for concrete adhesion that does not contain isophorone diamine in the curing agent. In the two-component mixed adhesive for concrete bonding according to claim 1,
The metaxylylenediamine derivative is a two-component mixed adhesive for adhering concrete, which is a phenol formalin reaction product of methylylenediamine. In the two-component mixed adhesive for concrete bonding according to claim 1,
A two-component mixed adhesive for concrete adhesion, wherein the content of the m-xylylenediamine derivative is 20% by mass or more and 30% by mass or less with respect to the total amount of the curing agent. In the two-component mixed adhesive for concrete bonding according to claim 3,
A two-component mixed adhesive for concrete adhesion, in which the mixing ratio of the main agent and the curing agent is 10: 1 to 10: 3 in terms of weight ratio. (A) A step of adjusting an adhesive by mixing a main agent and a curing agent.
(B) Step of applying the adhesive onto the first concrete,
(C) It has a step of forming a second concrete on the first concrete.
The main agent contains an epoxy resin and contains
The curing agent contains a diamine-based compound and a polyamine-based compound.
The diamine-based compound contains a meta-xylylenediamine derivative and polyoxypropylene diamine.
The polyamine-based compound contains an aliphatic polyamine or an alicyclic polyamine.
A concrete reinforcing method that does not contain isophorone diamine in the curing agent. In the concrete reinforcing method according to claim 5,
A concrete reinforcing method comprising a step of placing a reinforcing bar on the first concrete between the step (a) and the step (b). In the concrete reinforcing method according to claim 5,
The method for reinforcing concrete, wherein the m-xylylenediamine derivative is a phenol-formalin reaction product of m-xylylenediamine. In the concrete reinforcing method according to claim 5,
A concrete reinforcing method in which the content of the meta-xylylenediamine derivative is 20% by mass or more and 30% by mass or less with respect to the total amount of the curing agent. In the concrete reinforcing method according to claim 5,
A concrete reinforcing method in which the mixing ratio of the main agent and the curing agent is 10: 1 to 10: 3 in terms of weight ratio. In the concrete reinforcing method according to claim 5,
A concrete reinforcing method in which the surface temperature of the first concrete is 10 ° C. or higher and 30 ° C. or lower.