JP2017226557A - Repair method of concrete structure - Google Patents

Abstract

[PROBLEMS] To provide a concrete structure capable of forming a cured sulfuric acid-resistant mortar that has good mortar feeding and elongation by a trowel, does not crack after repair, and has a small weight change rate even when exposed to high-concentration sulfuric acid. Provides repair methods for things. SOLUTION: A mortar construction process for constructing a sulfuric acid resistant mortar prepared by mixing and kneading a sulfuric acid resistant cement composition and water at a place where a part of a concrete structure is removed, and a sulfuric acid resistant mortar. A cured body forming step of curing and forming a sulfate-resistant mortar cured body at a location, wherein the sulfate-resistant cement composition is cement, blast furnace slag, metakaolin, silica fume, A method for repairing a concrete structure containing fiber, alumina cement clinker aggregate and resin. [Selection] Figure 4

Description

  The present invention relates to a method for repairing a concrete structure such as a civil engineering / building facility under a corrosive environment such as a sewage treatment facility, an agricultural settlement wastewater facility, and a hot spring drainage facility.

  In sewage treatment facilities such as sewage treatment plants, sludge treatment plants, and sewage pipes, sulfate and organic acids contained in wastewater are decomposed by sulfate-reducing bacteria to generate hydrogen sulfide. Furthermore, the hydrogen sulfide changes into sulfuric acid due to the action of sulfur-oxidizing bacteria that live on the inner wall surface of concrete structures used in sewage treatment facilities, etc., so the inner wall surface of the concrete continues to be exposed to a sulfuric acid atmosphere. As a result, the concrete is corroded.

  As the corrosion of concrete structures progresses, it may lead to the leakage of sewage, as well as the collapse of the facilities themselves, so the suppression of corrosion of concrete structures is an important issue in cities where sewerage has developed. Yes.

  In Patent Document 1, a binder containing 40 to 65 parts by mass of alumina cement and 35 to 60 parts by mass of blast furnace slag fine powder, an aggregate, and two kinds of high-performance water reducing agents are mixed in a water / binder ratio. A salt-insulating cement mortar / concrete having chemical resistance obtained by kneading at 18 to 30% by mass is disclosed.

  Patent Document 2 contains Portland cement, blast furnace slag fine powder, and metakaolin, and 50 to 200 parts by weight of the blast furnace slag fine powder with respect to 100 parts by weight of the Portland cement, the Portland cement, and the blast furnace slag fine powder. An acid-resistant cement material is disclosed in which the metakaolin is 2 to 10 parts by weight with respect to 100 parts by weight of the total amount of the metakaolin.

Patent Document 3 discloses an alumina cement composition containing an alumina cement, a pozzolanic material, an alkali metal silicate having a SiO ₂ / R ₂ O molar ratio of 0.5 to 2, a thickener and a fluidizing agent, The thickener is at least one selected from a water-soluble alkylcellulose having a viscosity of 10,000 to 40,000 mPa · s, a water-soluble hydroxyalkylalkylcellulose, and a polymer containing a sulfonate group and an amidate group. The alumina cement composition is disclosed.

JP 2008-174429 A JP 2008-30968 A JP2012-082113A

  However, in the method of repairing concrete structures, sulfuric acid-resistant mortar using alumina cement is required to keep the water / binder ratio low in order to increase strength development, so that the miscibility is poor and it is kneaded with a hand mixer or the like. When doing so, the burden on the worker is large. In addition, when the water / binder ratio is lowered, the mortar becomes dense, the unit volume mass is as heavy as 2.10 kg / L or more, the feeding and elongation of the mortar by the iron is bad, and there is a problem that the operator is burdened. It was.

  In addition, mortar containing a large amount of blast furnace slag is used to improve sulfuric acid resistance, but sulfuric acid resistant mortar is often used as a base for resin lining, and a large amount of blast furnace slag is added. When using sulfuric acid resistant mortar, there are many calcium components, so if there is a partial defect in the resin lining of the surface layer or if there is a pinhole, the surface of the mortar layer will react with sulfate ions and calcium to cause gypsum. Ettringite and monosulfate are precipitated, the weight is increased, and the adhesiveness with the resin lining is lowered. Further, when pozzolanic fine powders such as blast furnace slag and silica fume are used, there is a problem that the shrinkage of the mortar becomes large and cracks are likely to occur after construction.

  Therefore, the present invention forms a sulfate-resistant mortar cured body that has good feeding and elongation of the mortar with a trowel, does not generate cracks after repair, and has a small weight change rate even when exposed to high-concentration sulfuric acid. The purpose is to provide a repair method for concrete structures that can be repaired.

  As a result of diligent studies to achieve the above object, the present inventors have found that a sulfate-resistant cement composition containing cement, blast furnace slag, metakaolin having a specific surface area, silica fume, fiber, alumina cement clinker aggregate and resin. As a result, the present inventors completed the present invention by finding a repair method that has good iron workability, has a small weight change rate even in a corrosive environment such as sulfuric acid, and generates less cracks.

That is, the present invention is a mortar construction process for constructing a sulfuric acid resistant mortar prepared by mixing and kneading a sulfuric acid resistant cement composition and water at a place where a part of a concrete structure is removed, and sulfuric acid resistance. A cured body forming step of curing a mortar to form a sulfuric acid resistant mortar hardened body at the location, the sulfuric acid resistant cement composition comprising cement, blast furnace slag, metakaolin , Silica fume, fiber, alumina cement clinker aggregate and resin, the BET specific surface area of metakaolin is 13 to 18 m ² / g, blast furnace slag 80 to 300 parts by mass, metakaolin 15 to 100 parts by mass of cement Repair of concrete structure including 100 parts by weight, silica fume 15 to 100 parts by weight, fiber 0.5 to 3.0 parts by weight An object of the present invention is to provide a law.

  According to the method for repairing a concrete structure of the present invention, the iron workability is good, the work is easy even in a narrow space such as a sewerage facility, and precipitation of gypsum and the like also occurs in a corrosive environment such as sulfuric acid. Since it is suppressed and the rate of change in weight is small, it is excellent in long-term durability because it is excellent in long-term adhesion with a resin lining. As described above, in the method for repairing a concrete structure according to the present invention, the reason why the iron workability is excellent and the weight change rate is excellent is not necessarily clear, but one reason is that In addition to the interaction between the components contained in the sulfate-resistant cement composition used in the repair method of concrete structures, the action caused by the combination of specific metakaolin and silica fume improves the workability of the iron. We believe that it contributes to the reduction of the rate of weight change.

  Preferred embodiments [(1), (2)] of the method for repairing a concrete structure of the present invention are shown below. In the present invention, it is more preferable to appropriately combine these aspects.

(1) The sulfuric acid resistant cement composition used in the method for repairing a concrete structure according to the present invention preferably has a BET specific surface area of silica fume of 15 to 25 m ² / g. Thereby, workability | operativity, such as extension and feeding in a trowel work, can be improved further.

  (2) The sulfuric acid resistant cement composition used in the method for repairing a concrete structure of the present invention further contains fine aggregate, and preferably contains 150 to 375 parts by mass of fine aggregate with respect to 100 parts by mass of cement. Thereby, workability | operativity, such as a cutting | disconnection in the ironing operation | work and separation | separation, can be improved more.

  According to the present invention, by using the sulfuric acid resistant cement composition, it is possible to provide a repairing method using a sulfuric acid resistant mortar with good ironing work, and therefore it is easy to apply to the repaired part. The burden on the operator can be reduced even in a narrow work space. In addition, since the rate of change in weight is small in a corrosive environment such as sulfuric acid, it is excellent in long-term adhesion with a resin lining, and the life of the structure can be extended.

It is sectional drawing which shows typically an example of the concrete structure which has a corrosion part and a peeling part to which one Embodiment of the repair method of the concrete structure of this invention is applied. It is sectional drawing which shows typically the concrete structure after removing the corrosion part of the concrete structure of FIG. It is sectional drawing which shows typically the concrete structure in which the primer layer was formed on the surface. It is a schematic cross section for demonstrating the mortar construction process in one Embodiment of the repair method of the concrete structure of this invention. It is a schematic diagram which shows the construction method by a spraying construction method.

  The preferable aspect of the repair method of the concrete structure of this invention is demonstrated below. The method for repairing a concrete structure according to the present embodiment is prepared by mixing and kneading a step of removing a corroded portion of the concrete structure, and a sulfuric acid resistant cement composition containing a predetermined component and water at the removed portion. A mortar construction process for constructing the sulfuric acid-resistant mortar, and a cured body forming process for curing the sulfuric acid-resistant mortar to form a sulfuric acid-resistant mortar cured body at the location. Hereinafter, the details of each step will be described with reference to the drawings. In addition, since embodiment based on this indication demonstrated below is an illustration for demonstrating this invention, this invention should not be limited to the following content.

<Removal process of corroded part of concrete structure>
FIG. 1 is a cross-sectional view schematically showing a partial cross section of a concrete structure 10 having a corroded portion and a peeled portion to which the method for repairing a concrete structure of the present embodiment is applied.

  The concrete structure 10 shown in FIG. 1 has a healthy part 11, a corroded part 12, and a peeled part 13 in order from the inside. The concrete structure 10 has a surface 10a at the time of new construction, but the surface portion is corroded by the corrosion generated in the corrosive environment, and a peeled portion 13 is generated in which a part of the concrete on the surface side is peeled off. . For this reason, part of the corroded portion 12 is exposed on the surface of the concrete structure 10 in some cases. In the repair method of the present embodiment, the surface portion of the concrete structure 10 is repaired to form the surface 10a at the time of new installation in order to obtain the same shape as at the time of new installation. In addition, the concrete structure 10 may have a reinforcing bar inside. Here, the case where corrosion has not reached the reinforcing bar inside the concrete structure will be described.

  First, in order to identify the corroded portion, the corroded portion 12 of the concrete structure is identified by investigations such as appearance observation and a sounding method. Next, the concrete structure 10 is suspended so that the corroded portion 12 is completely removed.

FIG. 2 is a cross-sectional view schematically showing the concrete structure after removing the corroded portion 12 of the concrete structure shown in FIG. The removal of the corroded portion 12 of the concrete structure can be performed by, for example, a hitting method such as a water jet or a breaker. However, when the hitting method is used, there is a risk of inducing microcracks in a healthy portion of the concrete structure. For this reason, a water jet is more preferable. When picking up with a water jet, it is performed at an appropriate discharge pressure so that the corroded portion 12 can be completely removed, and a discharge pressure of 200 MPa or more is preferable. The depth to be hulled is such that a phenolphthalein solution is sprayed on the hanger surface of the concrete structure to give a red color and the tensile strength becomes 1.5 N / mm ² or more. In addition, when the reinforcing bar is exposed by lashing, it is preferable to check the degree of corrosion of the reinforcing bar and, if necessary, to perform rust prevention treatment or new reinforcement.

  The concrete from which the corroded portion 12 is removed is coated with a water absorption adjusting agent (primer) or dampened with water on the suspended surface. In the case of using a water absorption adjusting agent, it is preferable to form the primer layer 15 of FIG. 3 by applying the water absorption adjusting agent and then drying it. As the water absorption adjusting agent, a synthetic resin emulsion diluted with water can be suitably used. As the water absorption adjusting agent, a brush, a lysing gun or the like can be appropriately selected and applied. When water dampening is performed, water is sprayed, and when the hanger surface starts to dry, a sulfuric acid resistant mortar is applied (construction of mortar).

  FIG. 3 is a cross-sectional view schematically showing a concrete structure in which the primer layer 15 is formed on the surface of the portion that has been removed. By forming such a primer layer 15, the adhesion between the concrete structure and the cured mortar can be further improved.

<Construction process of sulfuric acid resistant mortar>
FIG. 4 is a schematic cross-sectional view for explaining a construction process of the sulfuric acid resistant mortar of the present embodiment. A sulfuric acid resistant cement composition containing a predetermined component is kneaded with water to prepare a sulfuric acid resistant mortar. For kneading the sulfuric acid resistant cement composition and water, a hand mixer or a mortar mixer can be used as appropriate.

  The prepared sulfuric acid resistant mortar 16 is applied once or several times so as to cover the surface of the primer layer 15, and the acid resistant mortar 16 is filled to the position of the surface 10a when the concrete structure is newly installed. . The contents of the sulfuric acid resistant cement composition and the sulfuric acid resistant mortar will be described later.

A plastering method can be used for applying the sulfuric acid resistant mortar, and a spraying method can be used if the construction area is a large area of 10 m ² or more. In the plastering method, a plasterer craftsman puts an appropriate amount of sulfuric acid-resistant mortar on the iron plate, and applies the sulfuric acid-resistant mortar 16 to the portion where the corroded portion 12 is removed using a gold iron or the like. It is applied one to several times depending on the thickness of the corroded portion 12 of the concrete. The coating thickness at one time is 40 mm or less, and the coating thickness per day is usually up to about 50 mm.

  FIG. 5 is a schematic diagram showing a construction method by a spraying method. The spraying method is a method in which a sulfuric acid resistant mortar 16 is filled in a portion where the corroded portion 12 is scraped by spraying a sulfuric acid resistant mortar onto the concrete structure 10. As shown in FIG. 5, the apparatus used for the spraying method can be one provided with a mixer 21, a mortar pump 22 with a hopper, an air source 23, a pressure hose 24, and a spray gun 25. As an apparatus used for the spraying method, a hopper and a mortar pump may be separated.

  In the spraying method, it is preferable that the sulfuric acid resistant mortar is sprayed in one to several times on the portion where the corroded portion is removed. In the first construction, for example, sulfuric acid-resistant mortar is sprayed so as to have a thickness of about 20 to 40 mm. In the second and subsequent constructions, sulfuric acid-resistant mortar spraying is repeated so that the thickness is within 40 mm. In the final construction, sulfuric acid resistant mortar is sprayed so as to have a thickness of about 15 mm. Thereafter, the surface of the sulfuric acid resistant mortar 16 is finished with a scissors so that the concrete structure 10 and the sulfuric acid resistant mortar 16 are integrated.

  The surface of the sulfuric acid resistant mortar 16 is flat when the resin lining is applied to the surface layer of the sulfuric acid resistant mortar cured body formed in the subsequent curing body forming step, and when the mortar lining is applied or the sulfuric acid resistance When recoating mortar, finish with a comb iron. The surface layer is finished while spraying a primer or a curing agent as necessary.

<Hardened body formation process>
After applying the sulfuric acid resistant mortar, the sulfuric acid resistant mortar 16 is cured to form a cured body forming step of forming a sulfuric acid resistant mortar cured body. As a result, it is possible to obtain a concrete structure repaired by a sulfuric acid-resistant mortar cured body that has both excellent corrosion resistance and excellent adhesion to a resin lining.

  When applying a sulfuric acid-resistant mortar to the surface layer of the sulfuric acid-resistant mortar cured product or applying a mortar lining, make sure that the sulfuric acid-resistant mortar cured product is sufficiently cured and the surface layer is dried. If so, wet with water or apply primer. When the primer is applied, it is applied after the primer is sufficiently dried. When the resin lining is applied to the surface layer of the sulfuric acid resistant mortar cured body, it is confirmed that the surface of the sulfuric acid resistant mortar cured body is sufficiently dried.

<Sulfuric acid resistant cement composition>
Next, the sulfuric acid resistant cement composition used in the concrete structure repair method of the present embodiment will be described below. The sulfuric acid resistant cement composition used in the present embodiment includes cement, blast furnace slag, metakaolin, silica fume, fiber, alumina cement clinker aggregate, and resin.

  The cement can be used by selecting from Portland cement specified by JIS R 5210 “Portland cement”. Normal Portland cement, early strength Portland cement, super early strength Portland cement, moderately hot Portland cement, low heat Portland cement, sulfuric acid resistance Portland cement can be used. Among these, from the viewpoint of early strength development, it is preferable to use early-strength Portland cement or ultra-early-strength Portland cement.

The brane specific surface area of the cement is preferably 2600 to 5400 cm ² / g, more preferably 2800 to 5200 cm ² / g, and still more preferably 3000 to 5000 cm ² / g. The brain specific surface area of the cement is determined according to JIS R 5201 “Physical Test Method for Cement”. When the cement specific surface area of the cement is in the above preferred range, the workability is excellent.

  Blast furnace slag is a common cement admixture, and any commercially available product can be used. Among these, it is preferable to use blast furnace slag specified by JIS A 6206 “Blast furnace slag fine powder for concrete”. The blast furnace slag densifies the hardened body and improves sulfuric acid resistance due to latent hydraulic properties. By using the above-mentioned blast furnace slag, it is possible to form a mortar cured body excellent in chemical reactivity, particularly acid resistance.

The blast furnace slag has a brane specific surface area of preferably 2,000 to 8,000 cm ² / g, more preferably 2,500 to 6,000 cm ² / g, and still more preferably 3,000 to 5,000 cm ^2. / G. The brane specific surface area of the blast furnace slag is determined according to JIS R 5201 “Physical Test Method for Cement”. If the blast furnace slag has a Blaine specific surface area of less than 2,000 cm ² / g, the cured body will be insufficiently densified, and the sulfuric acid resistance will decrease. If it exceeds 8,000 cm ² / g, the particles will become finer. In the troweling operation, the adhesive strength to the trowel increases and the workability tends to deteriorate.

  The content of the blast furnace slag is 80 to 300 parts by mass, preferably 90 to 280 parts by mass, more preferably 100 to 260 parts by mass, and particularly preferably 110 to 250 parts by mass with respect to 100 parts by mass of cement. Part by mass. When the content of the blast furnace slag is 80 parts by mass with respect to 100 parts by mass of cement, the sulfuric acid resistance is lowered. When the content is more than 300 parts by mass, the sulfuric acid penetration depth is reduced, but the rate of change in weight in an environment exposed to sulfuric acid. Becomes larger.

Metakaolin is usually a kind of amorphous pozzolanic material obtained by heating kaolinite at 550 to 1200 ° C. and also called calcined kaolin. The main chemical components are Al ₂ O ₃ and SiO ₂ .

The BET specific surface area of metakaolin is 13 to 18 m ² / g, preferably 13.5 to 17.5 m ² / g, and particularly preferably 14 to 17 m ² / g. The BET specific surface area of metakaolin is determined according to JIS Z 8830 “Method for measuring specific surface area of powder (solid) by gas adsorption”. When the BET specific surface area of metakaolin is smaller than 13 m ² / g, the rate of change in weight in an environment exposed to sulfuric acid increases and workability also deteriorates. On the other hand, if it is larger than 18 m ² / g, handling as a powder becomes difficult, and the adhesiveness to the iron when mortar is increased increases the workability.

  The content of metakaolin is 15 to 100 parts by mass, preferably 30 to 90 parts by mass, and particularly preferably 45 to 80 parts by mass with respect to 100 parts by mass of cement.

  Silica fume is a common cement admixture, and any commercially available product can be used. Among these, it is preferable to use silica fume defined in JIS A 6207 “Silica fume for concrete”. Such a silica fume has the effect of improving the glazing workability by the bearing effect as well as the effect of improving the strength of the cured body. Moreover, the mortar hardening body which was further excellent in durability can be formed.

  The content of silica fume is 15 to 100 parts by weight, preferably 30 to 90 parts by weight, and particularly preferably 45 to 80 parts by weight with respect to 100 parts by weight of cement. If the content of metakaolin and silica fume is in the above range, there is no reduction in sulfuric acid resistance, and even when a large amount of blast furnace slag is blended, the weight change rate is small even in a corrosive environment such as sulfuric acid, and the unit volume of mortar The mass is light and the workability can be in a good range.

BET specific surface area of the silica fume is preferably 10 to 25 ² / g, more preferably 16~24m ² / g, more preferably 17~23.5m ² / g, particularly preferably is 18~23m ² / g . The BET specific surface area of silica fume is determined according to JIS Z 8830 “Method for measuring specific surface area of powder (solid) by gas adsorption”. When the BET specific surface area of silica fume is smaller than 15 m ² / g, the sulfuric acid resistance is lowered. Moreover, when larger than 25 m < ² > / g, the adhesiveness to a iron will increase and workability will deteriorate on the contrary.

  The fiber can be used as long as it is stable against acid, and organic fibers such as vinylon fibers, nylon fibers, and polypropylene fibers, and inorganic fibers such as alkali-resistant glass fibers can be used. Two or more types can be used in combination. A fiber having a fiber diameter of 0.3 to 30 μm and a fiber length of 3 to 30 mm is preferably used, and the effect of suppressing cracks after construction is high.

  The fiber content is 0.5 to 3.0 parts by mass, preferably 1.0 to 2.75 parts by mass, and more preferably 1.5 to 2.5 parts by mass with respect to 100 parts by mass of cement. Part. When the fiber content is less than 0.5 parts by mass with respect to 100 parts by mass of cement, the crack suppression effect becomes insufficient. On the other hand, if it exceeds 3.0 parts by mass, workability such as iron elongation and iron feeding deteriorates, such being undesirable.

The alumina cement clinker aggregate has a low SiO ₂ content as a chemical component and is excellent in sulfuric acid resistance. The alumina cement clinker aggregate preferably does not contain particles with a particle diameter of 2.5 mm or more, and more preferably does not contain particles with a particle diameter of 1.2 mm or more. The particle size is determined according to JIS A 1102 “Aggregate Screening Test Method” using several sieves having different nominal dimensions as defined in JIS Z8801-1 “Sieving Screens—Part 1: Metal Mesh Screen”. It can be determined according to In the present specification, “not including particles having a particle diameter of 2.5 mm or more” means that the mass fraction of particles remaining in the sieve when using a sieve having a sieve opening of 2.5 mm is 0%. When the particle diameter of the alumina cement clinker aggregate exceeds 2.5 mm, the aggregate is exposed when thin coating is applied, and the finish of the surface layer is deteriorated, which becomes a factor that hinders adhesion to the resin lining.

The mass fraction (%) remaining on each sieve of alumina cement clinker aggregate is
Preferably, the sieve opening is 0.6 to 0 to 30%, the sieve opening to 0.3 mm is 18 to 68%, the sieve opening is 0.15 mm to 53 to 85%,
More preferably, it is 3 to 28% at 0.6 mm sieve opening, 20 to 65% at 0.3 mm sieve opening, and 58 to 82% at 0.15 mm sieve opening,
Particularly preferably, the sieve opening is 8 to 25% at 0.6 mm, 35 to 60% at 0.3 mm sieve opening, and 63 to 80% at 0.15 mm sieve opening.

  When the mass fraction remaining on each sieve of the alumina cement clinker aggregate is in the above range, the surface accuracy and sulfuric acid resistance are further improved.

  The coarse particle ratio of the alumina cement clinker aggregate is preferably 1.00 to 2.00, more preferably 1.05 to 1.90, still more preferably 1.08 to 1.80, particularly Preferably it is 1.10-1.70. When the coarse particle ratio of the fine aggregate is within the above range, the acid resistance and strength can be further improved while improving the ironing workability.

  The content of the alumina cement clinker aggregate is preferably 30 to 200 parts by mass, more preferably 50 to 175 parts by mass, and particularly preferably 75 to 150 parts by mass with respect to 100 parts by mass of cement. When the content of the alumina cement clinker aggregate is less than 30 parts by mass, the sulfuric acid resistance decreases. When the content of the alumina cement clinker aggregate is large, the sulfuric acid resistance is improved, but it is not practical in terms of economy, so it is preferable that the upper limit is 200 parts by mass.

  The resin is not particularly limited as long as it can ensure adhesion with the concrete to be repaired and does not impair sulfuric acid resistance, and use a known resin emulsion or re-emulsified resin powder such as acrylic resin, vinyl acetate resin, etc. Can do. That is, the resin includes (meth) acrylic acid, (meth) acrylic acid derivatives such as (meth) acrylic acid esters, α-olefin compounds such as ethylene and vinyl acetate, vinyl compounds such as styrene, and polymerization components such as butadiene. A polymer or a copolymer can be used, and these resins can be used alone or in combination of two or more.

  The resin is preferably an acrylic resin from the viewpoint of sulfuric acid resistance. Examples of acrylic resins include (meth) acrylic such as acrylic acid and methacrylic acid; polymers of (meth) acrylic acid derivatives such as (meth) acrylic acid esters; polymers of (meth) acrylic acid derivatives and styrene, and the like. Can be mentioned. Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Among these, a polymer of a (meth) acrylic acid derivative and styrene is more preferable.

  The content of the resin is preferably 5 to 40 parts by mass, more preferably 7 to 30 parts by mass, and particularly preferably 10 to 20 parts by mass with respect to 100 parts by mass of the cement. When the resin content is less than 5 parts by mass with respect to 100 parts by mass of cement, the adhesiveness to the repaired part of the concrete structure is reduced, and when it is greater than 40 parts by mass, the compressive strength of the mortar is reduced. This may cause deterioration and deterioration of workability. Here, when the resin is a resin emulsion, the content of the above-mentioned resin refers to the content of a solid content obtained by removing moisture from the resin emulsion.

  It is preferable that the sulfuric acid resistant cement composition used in the method for repairing a concrete structure of the present embodiment further includes fine aggregate. Further, the fine aggregate preferably does not contain particles of 2.5 mm or more, and preferably has a mass fraction of particles having a particle diameter of 1.2 mm or more of less than 20%. As such fine aggregates, those selected from sands such as quartz sand, river sand, land sand, sea sand and crushed sand can be suitably used.

  The particle size of the fine aggregate was determined by using several sieves with different nominal sizes as defined in JIS Z8801-1 “Sieving sieve for test-Part 1: Metal mesh sieve”. It can be determined according to “Sieving Test Method”. In the present specification, the “mass fraction of particles having a particle diameter of 1.2 mm or more” refers to the mass fraction (%) of particles remaining in the sieve when a sieve having a sieve opening of 1.2 mm is used. .

  When the fine aggregate contains particles having a particle diameter of 1.2 mm or more in a mass fraction of 20% or more, the ironing workability of the sulfuric acid resistant cement composition tends to decrease. There is no restriction | limiting in particular in the lower limit of the said mass fraction, and 0% may be sufficient. In order to obtain excellent ironing workability, the mass fraction of particles having a particle diameter of 1.2 mm or more in the fine aggregate is preferably 0 to less than 20%, more preferably 1 to 15%, Preferably it is 2 to 12%, and particularly preferably 2 to 10%.

The mass fraction (%) that remains on each sieve of fine aggregate
Preferably, the sieve opening is 37 to 67% at 0.6 mm, the sieve opening is 0.3 to 72 to 100%, the sieve opening is 0.15 mm and 80 to 100%,
More preferably, it is 42 to 62% at 0.6 mm sieve opening, 77 to 97% at 0.3 mm sieve opening, 85 to 100% at 0.15 mm sieve opening,
Particularly preferred is 47 to 58% at 0.6 mm sieve opening, 82 to 92% at 0.3 mm sieve opening, and 90 to 100% at 0.15 mm sieve opening.

  When the mass fraction remaining on each sieve of the fine aggregate is within the above range, the iron workability is more excellent.

  The coarse particle ratio of the fine aggregate is preferably 2.10 to 2.60, more preferably 2.15 to 2.55, still more preferably 2.18 to 2.52, and particularly preferably. 2.20 to 2.50. When the coarse particle ratio of the fine aggregate is within the above range, the acid resistance and strength can be further improved while improving the ironing workability.

  The content of the fine aggregate is preferably 150 to 375 parts by mass, more preferably 175 to 350 parts by mass, still more preferably 200 to 325 parts by mass, particularly preferably 100 parts by mass of cement. Is 225 to 300 parts by mass. By adjusting the content of the fine aggregate to the above range, the acid resistance and strength can be further improved while improving the ironing workability.

  In the sulfuric acid resistant cement composition used in the method for repairing a concrete structure according to the present embodiment, when an alumina cement clinker aggregate and a fine aggregate are used in combination, the particle diameter does not include particles of 2.5 mm or more. The mass ratio of particles having a particle diameter of 1.2 mm or more is preferably less than 20% by mass. When particles having a particle diameter of 1.2 mm or more are contained in a mass fraction of 20% or more, the ironing workability of the sulfuric acid resistant cement composition tends to be lowered. There is no restriction | limiting in particular in the lower limit of the said mass fraction, and 0% may be sufficient. In order to obtain excellent soldering workability, the mass fraction of particles having a particle diameter of 1.2 mm or more in the fine aggregate is preferably 0 to less than 20%, more preferably 0.5 to 15%. More preferably, it is 0.7 to 12%, and particularly preferably 1 to 10%.

When using a combination of alumina cement clinker aggregate and fine aggregate, the mass fraction (%) remaining in each sieve is
Preferably, it is 29 to 59% at a sieve opening 0.6 mm, 62 to 92% at a sieve opening 0.3 mm, 75 to 100% at a sieve opening 0.15 mm,
More preferably, it is 34 to 54% at 0.6 mm sieve opening, 67 to 87% at 0.3 mm sieve opening, and 80 to 100% at 0.15 mm sieve opening,
Particularly preferably, the sieve opening is 39 to 49% at 0.6 mm, 72 to 85% at 0.3 mm, and 85 to 95% at 0.15 mm.

  When the mass fraction remaining in each sieve is in the above range, it has better iron workability, and more excellent surface accuracy and sulfuric acid resistance.

  When the alumina cement clinker aggregate and the fine aggregate are used in combination, the coarse particle ratio is preferably 1.85 to 2.45, more preferably 1.95 to 2.35, and still more preferably 2. It is 00-2.30, Most preferably, it is 2.05-2.25. When the coarse particle ratio is in the above range, the acid resistance and strength can be further improved while improving the ironing workability.

  From the viewpoint of workability, strength, water retention, etc., the sulfuric acid resistant cement composition used in the concrete structure repair method of the present embodiment includes a fluidizing agent, a water retention agent, a thickening agent, and a coagulation adjustment as necessary. An agent or the like may be included.

  The fluidizing agent can be appropriately added as long as it does not impair the characteristics of the sulfuric acid resistant cement composition used in the method for repairing a concrete structure of the present embodiment. By appropriately adjusting the content of the fluidizing agent, the flow value of the sulfuric acid resistant mortar containing the sulfuric acid resistant cement composition and water can be adjusted.

  The fluidizing agent is selected from commercially available fluidizing agents such as formaldehyde condensate of melamine sulfonic acid, casein, calcium caseinate, polycarboxylic acid, polyether, and polyether carboxylic acid, which have both water reduction effect and suitable fluidity. can do. As the fluidizing agent contained in the highly acid-resistant hydraulic composition of the present embodiment, it is particularly preferable to use a commercially available fluidizing agent such as polyether-based or polyether carboxylic acid. From the viewpoint of imparting a predetermined fluidity while maintaining acid resistance, the fluidizing agent preferably contains a polycarboxylic acid ester.

  The content of the fluidizing agent is preferably 0.1 to 2.0 parts by mass, more preferably 0.15 to 1.75 parts by mass, and still more preferably 0.2 to 1. parts by mass with respect to 100 parts by mass of cement. 5 parts by mass, particularly preferably 0.25 to 1.50 parts by mass. By adjusting the content of the fluidizing agent to the above-described range, preferable fluidity can be imparted, and the tanning workability and the spraying workability can be improved.

<Sulfuric acid resistant mortar>
Next, the sulfuric acid resistant mortar used for the repair method of the concrete structure of this embodiment is demonstrated below. The sulfuric acid resistant mortar used in this embodiment includes the sulfuric acid resistant cement composition and water. More specifically, the sulfuric acid resistant cement composition and water can be blended and kneaded. Here, the flow value and unit volume mass of sulfuric acid resistant mortar can be adjusted by changing the compounding quantity of water suitably. Thus, the sulfuric acid resistant mortar suitable for a use can be prepared by changing the compounding quantity of water suitably. Here, the flow value is a value measured according to the test method described in JIS R 5201 “Physical test method for cement”, and the unit volume mass is JIS A 1171 “Test method for polymer cement mortar. It is a value (unit: kg / L) measured based on the test method described in the above.

  The content of water is preferably 15 to 25 parts by mass, more preferably 17 to 24 parts by mass, and further preferably 19 to 23 parts by mass with respect to 100 parts by mass of the sulfuric acid resistant cement composition.

  When the resin contained in the sulfuric acid resistant cement composition is a resin emulsion, the water content needs to consider the amount of water in the resin emulsion. Therefore, the total amount of water and water in the resin emulsion is adjusted to the above-described preferable water content.

  The flow value of the sulfuric acid resistant mortar used for this embodiment becomes like this. Preferably it is 145-210 mm, More preferably, it is 150-200 mm, More preferably, it is 155-180 mm.

  By setting the water content and flow value of the sulfuric acid resistant mortar within the above-mentioned ranges, the spraying workability is improved in addition to the ironing workability.

  The unit volume mass of the sulfuric acid resistant mortar used in the present embodiment is preferably 1.80 to 2.10 kg / L, more preferably 1.85 to 2.08 kg / L, still more preferably 1. 90 to 2.06 kg / L.

  When the unit volume mass is in the above-mentioned range, while maintaining good workability of the sulfuric acid resistant mortar (good paintability and sprayability), moderate compressive strength to integrate with the concrete structure and It is possible to obtain a sulfuric acid-resistant mortar cured body having even better adhesiveness.

<Sulfuric acid resistant mortar cured product>
The sulfuric acid resistant mortar cured body used in the method for repairing a concrete structure of the present embodiment can be obtained by curing the above sulfuric acid resistant mortar. The sulfuric acid resistant mortar cured body will be described below. The sulfuric acid resistant mortar cured product used in the present embodiment can be suitably used as a repaired mortar cured product. That is, the sulfuric acid-resistant mortar cured product of the present embodiment formed by curing the sulfuric acid-resistant mortar has a small weight change rate even in a corrosive environment such as sulfuric acid, has excellent crack resistance, and long-term durability. Excellent.

  Here, the weight change rate means that a sulfuric acid-resistant mortar prepared under 20 ° C. and 65% RH conditions is packed in a φ50 × 100 mm cylindrical mold and cured for 24 hours. Cured sulfuric acid mortar, which was immersed in a 10% by mass sulfuric acid solution for 10 days, based on the weight of the cured sulfuric acid mortar cured in water for 20 days and further cured in air at 20 ° C. and 65% RH for 14 days. It is a value (unit:%) obtained by dividing the difference obtained by subtracting the reference weight from the weight of the weight and dividing the difference by the reference weight.

  The weight change rate of the sulfuric acid resistant mortar cured product used in the present embodiment is preferably −1.0 to 4.5%, more preferably −0.5 to 4.0%, and still more preferably. It is 0.0 to 3.7%.

  When the rate of change in weight is in the above-described range, the sulfate-resistant mortar cured product has excellent long-term adhesion with the resin lining, and the structure can have a long life.

Here, the resistance to crazing, against direct wind speed 3m / s to the coating surface, while irradiating from a distance 850mm from the coated surface of the xenon lamp, when performing construction and curing the coated surface, 900 cm ² per The number of cracks is measured.

As for the crack resistance of the cured sulfuric acid-resistant mortar used in the present embodiment, the number of cracks per 900 cm ² is preferably 3 or less, more preferably 1 or less, and particularly preferably 0.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  The contents of the present invention will be specifically described below with reference to examples. Note that the present invention is not limited to these examples.

[Materials used]
The materials used in Examples and Comparative Examples are described below.
(1) Cement [C]
・ High-strength Portland cement (manufactured by Ube Mitsubishi Cement Co., Ltd., Blaine specific surface area 4,480 cm ² / g)
(2) Blast furnace slag [SG]
・ Blast furnace slag specified by JIS A 6206 (Blaine specific surface area 4,660 cm ² / g “measured according to JIS R 5201”)
(3) Metakaolin [MK] (BET method specific surface area 15.9 m ² / g “measured according to JIS Z 8830”)
(4) Silica fume [SH] (BET method specific surface area 21.9 m ² / g “measured according to JIS Z 8830”)
(5) Fiber [F]
・ Vinylon fiber (manufactured by Kuraray Co., Ltd., trade name: KVS702, fiber diameter 26.2 μm, fiber length 5 mm)
(6) Alumina cement clinker aggregate [AK] (Kelneos Japan Co., Ltd., aggregate particle size composition (mass fraction remaining between each continuous sieve, mass fraction remaining on each sieve) and coarse particle ratio 1)

  The aggregate particle size was measured according to JIS A 1102 “Aggregate Screening Test Method”.

(7) Fine aggregate-Fine aggregate A [SA-A] (Table 2 shows the particle size composition and coarse particle ratio of the aggregate)
Fine aggregate B [SA-B] (Table 3 shows the particle size composition and coarse particle ratio of the aggregate)

(8) Resin [RE]
・ Re-emulsified resin powder (main component: styrene-acrylic copolymer)

(9) Fluidizer [FL]
・ Polyether ・ Polycarboxylic acid based fluidizer

[Preparation (manufacture) of sulfuric acid resistant cement composition]
In a constant temperature and humidity chamber at a temperature of 20 ° C. and a relative humidity of 65%, the above materials (total amount: 5 kg each) were blended with the formulation No. 1 shown in Table 4. It measured in the ratio of 1-6, and it mixed for 3 minutes using the rotary drum mixer, and obtained the acid-sulfur-resistant cement composition.

  From Table 4, formulation no. 2-No. Table 5 shows the particle size constitution and the coarse particle ratio of the aggregate obtained by combining AK and SA-B contained in each of the six formulations.

  With respect to 1 kg of each formulation prepared at the ratio shown in Table 4, the kneading water amount shown in Table 6 was blended and kneaded to prepare sulfuric acid resistant mortars of Examples 1 to 3 and Comparative Examples 1 to 3. The kneading was carried out under conditions of a temperature of 20 ° C. and a relative humidity of 65% using a Hobart mixer at a low speed for 1 minute, then scraping the inside of the mixing container with a stirring blade and further kneading for 2 minutes.

[Evaluation of physical properties of sulfuric acid resistant mortar and cured sulfuric acid resistant mortar]
The unit volume mass, flow value, trowel workability, and sulfuric acid resistance (weight change rate) of the cured sulfuric acid mortar of each of the prepared examples and comparative examples were measured. The measurement results were as shown in Table 6. Each measurement was performed by the method shown below.

(1) Measurement method of flow value The flow value was measured based on the test method described in JIS R 5201 "Physical test method of cement".
(2) Measuring method of unit volume mass The unit volume mass was measured based on the test method described in JIS A 1171 “Test method of polymer cement mortar”.
(3) Evaluation method of iron workability A mortar of sulfuric acid resistance was applied to a concrete board, and the workability (feeding, iron elongation, iron separation, iron cutting) at that time was evaluated. Iron feeding is an evaluation of the small force (or weight) applied to the mortar when it is spread evenly, and trowel elongation is the application of a specified amount of mortar at once. It is an evaluation of the size of the area that can be spread (coating area), and the detachment from the iron is an evaluation of the low adhesive strength (stickiness) to the iron when the mortar is spread vertically and horizontally, The term “cutting iron” refers to the evaluation of the small amount of iron attached to the iron when the iron is separated from the mortar after spreading the mortar (the iron residue). Further, this workability was evaluated in five stages (5: very good, 4: good, 3: normal, 2: poor, 1: very bad).
(5) Method for evaluating sulfuric acid resistance Two layers of sulfuric acid-resistant mortar were packed in a cylindrical frame of φ50 × 100 mm, and each layer was tamped 15 times. After demolding after 24 hours, the specimen was cured in water at a temperature of 20 ° C. for 14 days, and further cured in an atmosphere at a temperature of 20 ° C. and a relative humidity of 65% for 14 days to prepare a test specimen. After measuring the weight (A) of the specimen after curing, the specimen was immersed in a 10% by mass sulfuric acid solution for 10 days, washed with water, wiped off the moisture of the specimen, and measured for weight (B). The weight change rate was calculated using the following formula (1).
Weight change rate = (B−A) / A × 100 (1)

[Measurement result]
As shown in Table 6, with respect to 100 parts by mass of cement, 80 to 300 parts by mass of blast furnace slag, 15 to 100 parts by mass of metakaolin with a BET specific surface area of 13 to 18 m ² / g, 15 to 100 parts by mass of silica fume, fiber The sulfuric acid resistant mortars (Examples 1 to 3) prepared using the sulfuric acid resistant cement composition containing 0.5 to 3.0 parts by mass are light in unit volume mass of 2.10 kg / L or less, Also, the iron feed was as good as 4 or more, and the rate of change in weight when immersed in a 10% by mass sulfuric acid solution was also as good as 4% or less.

  In addition, the sulfate-resistant mortar containing no metakaolin and silica fume (Comparative Examples 1 and 2), and the sulfuric acid-resistant mortar containing only silica fume (Comparative Example 3) had an iron elongation and iron feed of 3 or less. The workability was poor, and the weight change rate of the cured sulfuric acid-resistant mortar when immersed in a 10% by mass sulfuric acid solution was also 5% or more.

[Evaluation of crack resistance of cured sulfuric acid mortar]
In Table 4, the formulation No. 4 based on No. 4, the blending ratio of F (fiber) only was changed to the ratio shown in Table 7. 7 to 11 were prepared in the same manner as in the preparation (production) of the above-mentioned sulfuric acid resistant cement composition, and sulfuric acid resistant mortar was prepared with the amount of kneading water shown in Table 7. Here, the formulation No. 9 is the formulation No. of Table 4. Same as 4.

  The unit volume mass, flow value, and crack resistance of the cured sulfuric acid mortar were measured for each of the prepared sulfuric acid resistant mortar compositions of each example and comparative example. The measurement results are as shown in Table 7. The measurement was performed by the method shown below.

(1) Crack resistance Sulfur-resistant mortar was applied to a slate plate using a trowel so that the coating area was 900 cm ² with a thickness of 10 mm, and further 850 mm away from the mortar surface while applying a wind of 3 m / s. Xenon lamp was irradiated from the place where it was done. 30 minutes after painting, the surface of the sulfuric acid resistant mortar was flattened with a trowel, and after 5 days, the occurrence of cracks was confirmed. Moreover, this crack resistance was evaluated in five steps (per 900 cm ² , A: no crack, B: 1 to 3, C: 4 to 6, D: 7 to 9, E: 10 or more). The results are shown in Table 7.

[Measurement result]
As shown in Table 7, with respect to 100 parts by mass of cement, Examples 4 to 7, which are in the range of 0.5 to 3 parts by mass of fibers, have a crack resistance evaluation after repair of B or more and have good crack resistance. It was confirmed.

  From the above results, the sulfuric acid resistant mortar formed from the sulfuric acid resistant cement composition used in the method for repairing a concrete structure of the present embodiment has good iron workability such as iron feeding and iron elongation, and sulfuric acid resistance. It was confirmed that the cured mortar has a small weight change rate even when exposed to a high concentration of sulfuric acid, and can suppress the occurrence of cracks even under adverse conditions such as ventilation and solar radiation.

  According to the present invention, trowel workability (feeding and elongation of mortar, etc.) at the time of application is good, the rate of change in weight is small even in an acidic corrosive environment such as high-concentration sulfuric acid, and durability for adhesion to the lining material It is possible to provide a sulfate-resistant cement composition and a sulfate-resistant mortar that can form a cured sulfuric acid-resistant mortar that is superior to the above. In addition, it is possible to provide a cured sulfuric acid mortar that has a small weight change rate and is excellent in cracking resistance even when exposed to a high concentration of sulfuric acid or the like.

  DESCRIPTION OF SYMBOLS 10 ... Concrete structure, 10a ... Surface, 11 ... Healthy part, 12 ... Corrosion part, 13 ... Exfoliation part, 15 ... Primer layer, 16 ... Acid-resistant mortar composition, 21 ... Mixer, 22 ... Mortar pump, 23 ... Compressor 24 ... pressure hose, 25 ... spray nozzle.

Claims (3)

A mortar construction process for constructing a sulfuric acid resistant mortar prepared by mixing and kneading a sulfuric acid resistant cement composition and water in a place where a part of the concrete structure is removed, and curing the sulfuric acid resistant mortar A cured body forming step of forming a sulfuric acid-resistant mortar cured body at the location, and a repair method for a concrete structure,
The sulfuric acid resistant cement composition contains cement, blast furnace slag, metakaolin, silica fume, fiber, alumina cement clinker aggregate and resin,
The BET specific surface area of the metakaolin is 13-18 m ² / g,
80 to 300 parts by mass of the blast furnace slag, 15 to 100 parts by mass of the metakaolin, 15 to 100 parts by mass of the silica fume, and 0.5 to 3.0 parts by mass of the fiber with respect to 100 parts by mass of the cement.
Repair method for concrete structures. The silica fume has a BET specific surface area of 10 to 25 m ² / g.
The method for repairing a concrete structure according to claim 1. The sulfuric acid resistant cement composition further includes a fine aggregate, and includes 150 to 375 parts by mass of a fine aggregate with respect to 100 parts by mass of the cement.
The repair method of the concrete structure of Claim 1 or Claim 2.