JP5376794B2 - Acid-resistant composite and repair method - Google Patents

Description

  The present invention mainly relates to an acid-resistant composite and a repair method used for repairing a deteriorated portion of a concrete structure, particularly for repairing a concrete structure such as a hot spring zone or a sewage treatment facility.

In sewage and hot spring areas, hydrogen sulfide is generated due to the influence of microorganisms and volcanic gas, and sulfuric acid is generated when water intervenes there. In such places, corrosion of the concrete structure becomes a problem. When a cement-cured material such as concrete is brought into contact with sulfuric acid, it reacts with calcium hydroxide in the concrete to generate dihydrate gypsum, and further, ettringite is generated to cause expansion and deterioration of the concrete.
As a method for repairing a deteriorated portion with sulfuric acid, a method of performing resin lining after removing a deteriorated portion with a water jet and repairing a cross section or adjusting the unevenness is performed. As a restoration material used for this, a material in which a polymer is blended with blast furnace granulated slag (Patent Document 1), a material made of alumina cement (Patent Documents 2 and 3), a large amount of fine powder such as blast furnace granulated slag and silica fume. Mixed cement mortar is used (Patent Document 4). Moreover, it is a material using alumina cement and fine powder of blast furnace slag, containing alumina cement particles of 5 μm or less in an amount of 25% by weight or less and containing lithium salt (Patent Document 5), or alkali metal salt of sulfonic acid as a substituent. The material (patent document 6) etc. which contain the water-soluble organic compound which has 0.5-4 mass parts with respect to 100 weight part of cements are proposed.
Japanese Patent Laid-Open No. 03-290348 JP 2003-89565 A JP 2004-292245 A JP 2000-128618 A JP 2002-293603 A JP 2003-292362 A

The resin components used for resin lining include tar epoxy resin, epoxy resin, epoxy resin with ceramic powder, vinyl ester resin, non-styrene type vinyl ester resin, vinyl ester resin with glass flakes, unsaturated polyester resin, whisker. Entered modified silicone resin, polyurethane resin, polyurea resin, acrylic resin (The acrylic resin here is an acryloyl modified acrylic resin obtained by radical polymerization of a prepolymer in which an acryloyl group is added via an urethane bond to an acrylic rubber base polymer. (A non-patent document 1) is known in which a 1 mm coating film is formed by a single application, indicating a relatively high viscosity).
Edited by Japan Sewerage Corporation, Corrosion and corrosion control technology for sewer concrete structures, and anti-corrosion technology guideline and manual, Publisher Sewer Business Management Center, December 2002

  In the method of lining a resin after repairing concrete with a cement-based material, it is usual to perform multiple layers of resin lining such as primer coating, intermediate coating, and top coating. Depending on the type of resin, there are cases in which intermediate coating or top coating is performed twice, and many steps are required to finally form the resin layer.

  An object of the present invention is to provide an acid-resistant composite and a repair method that are easy to repair a concrete structure deteriorated with sulfuric acid or the like and that have excellent durability.

The present invention employs the following means in order to solve the above problems.
(1) An acid-resistant composite in which a hardened material layer of an acrylic resin having a viscosity of 100 to 500 mPa · s is combined with a hardened material layer having a porosity of 10 to 50% by volume of a hydraulic material containing alumina cement and blast furnace slag. Is the body.
(2) The acid-resistant composite according to (1), wherein the cured body layer of the hydraulic material contains silica fume and / or fly ash.
( 3 ) The cured body layer of the acrylic resin has a monofunctional (meth) acrylate having an ethylenically unsaturated double bond in one molecule and / or a polyfunctional having an ethylenically unsaturated double bond in one molecule ( The acid-resistant composite according to (1) or (2) above, which is obtained by polymerizing a liquid mainly composed of (meth) acrylates containing a (meth) acrylate, a polymerization initiator, and a decomposition accelerator. is there.
( 4 ) A concrete repair method characterized by forming the acid-resistant composite according to any one of (1) to ( 3 ) on a concrete surface.

  The acid-resistant composite of the present invention has better acid resistance than ordinary concrete and mortar, and unlike conventional resins, it does not need to be applied in several layers and can be repaired efficiently. There are effects such as being excellent in.

  Hereinafter, the present invention will be described in detail.

Cement to further improve the sulfuric acid in the present invention, to use an alumina cement. Alumina cement, unlike Portland cement, excellent resistance to sulfuric acid to form a cured product without generating a hydrated lime as hydrated product. The alumina cement is obtained from a clinker pulverized product containing monocalcium aluminate as a main mineral. For example, alumina cement No. 1 or alumina cement No. 2 can be used.
The fineness of the alumina cement is preferably a brane specific surface area of 2000 to 8000 cm ² / g in terms of hydration activity. Moreover, as the alumina cement whose particle size has been adjusted, particles having a particle diameter of 5 μm or less being suppressed to less than 30% by mass are preferable because shrinkage when cured is reduced.

When these cements are used as a restoration material, it is usually preferable to use mortar or concrete mixed with sand or gravel.
Moreover, it can be used as long as the combined use with any admixture used as an admixture (agent) for cement does not impair the sulfuric acid resistance. For example, AE agent, water reducing agent, high performance water reducing agent, high performance AE water reducing agent, foaming agent, foaming agent, separation reducing agent, setting modifier, quick setting agent, rust preventive agent, waterproofing agent, shrinkage reducing agent, swelling Agents, high-strength admixtures, antifreeze agents, polymer dispersions, antifoaming agents, hydration heat reducing agents, alkali aggregate reaction inhibitors, efflorescence inhibitors, rapid hardening materials, fibers, clay minerals and the like.

The blast furnace slag used in the present invention is a fine powder produced by pulverizing molten slag, which is a by-product generated simultaneously with pig iron in a blast furnace, with water, air, etc., and pulverized blast furnace slag. As the powder, it is preferable to use, for example, those specified in JIS A 6206 or equivalents thereof.
Although the usage-amount of blast furnace slag will not be specifically limited if it uses in the range which does not affect acid resistance performance or hardening performance, 50-150 mass parts is preferable with respect to 100 mass parts of cement.

The fly ash used in the present invention is a glassy by-product that is produced as a by-product when burning pulverized coal in a thermal power plant or the like, and is approximately 20 to 30 μm in spherical shape. For example, it is specified in JISA 6201. Fly ash is used.
Although the usage-amount of fly ash will not be specifically limited if it uses in the range which does not affect acid resistance performance or hardening performance, 5-30 mass parts is preferable with respect to 100 mass parts of cement.

The silica fume used in the present invention is mainly composed of amorphous SiO ₂ generated when metal silicon, ferrosilicon or the like is produced (generally 85 to 90%), and has a spherical ultra-fine diameter of about 0.1 μm or less. Fine particles.
Although the usage-amount of a silica fume will not be specifically limited if it uses in the range which does not affect an acid-proof performance or hardening performance, 2-15 mass parts is preferable with respect to 100 mass parts of cement.

The aggregate used in the present invention is not particularly limited, and is a generally available aggregate. For example, silica aggregate, limestone aggregate, heavy aggregate, lightweight aggregate and the like can be mentioned. The use of aggregates other than limestone aggregate is preferred in terms of acid resistance.
The amount of aggregate used is not particularly limited as long as it is used in a range that does not affect the acid resistance performance and fluidity, but the total amount of cement and blast furnace slag or a mixture of these with fly ash and silica fume added is 100 parts by mass. On the other hand, a mass part is preferable. 150-400 mass parts is preferable.

The hydraulic material used in the present invention is applied by a trowel coating method, a spraying method, a grout method, or the like after adding water and kneading during construction. In each construction method, it is important to adjust and construct so as to obtain an appropriate mixing state.
Although the amount of water varies depending on each method, it is difficult to limit the amount of water in general. Normally, if it is commercially available, the material design is tailored to each method of construction, so refer to the construction manuals and catalogs of each manufacturer that supplies the material, add appropriate water and mix. do it.

In the acid-resistant composite of the present invention, when an acrylic resin is combined with a cured layer of a hydraulic material, it is important that an acrylic resin is impregnated with the cured material surface layer of the hydraulic material to form a combined layer as deep as possible. It is. Therefore, the porosity of the cured material of the hydraulic material is 10 to 50% by volume. If it is less than 10% by volume, the penetration depth is small and pinholes are likely to occur. If it exceeds 50% by volume, the acrylic resin penetrates too much, increasing the amount of use and affecting the economy.
The porosity of the cured product of the hydraulic material of the present invention is not particularly limited. For example, air entraining agent, foaming agent, foaming agent, lightweight aggregate, aggregate with adjusted particle size distribution and particle size, etc. Adjustments can be made using.

The acrylic resin used in the present invention is composited with a cured body layer of a hydraulic material. A low-viscosity material that can be applied mainly to a cured material surface of a hydraulic material and impregnated inside the cured material to form a composite layer of the cured material and an acrylic resin is preferable.
The uncured acrylic resin is mainly composed of (meth) acrylates, a polymerization initiator, and a decomposition accelerator. As a preparation method, (meth) acrylates not containing a polymerization initiator and a decomposition accelerator are divided into two, and a polymerization initiator (liquid A) is added to one and a decomposition accelerator (liquid B) is added to the other. When the liquid acrylic resin is applied, the liquid A and the liquid B may be mixed and applied to the surface of the cured body using a brush or a roller. After application, (meth) acrylates are polymerized to form a cured layer of acrylic resin.
In the present invention, the viscosity of the mixed uncured acrylic resin is set to 100 to 500 mPa · s . If it is less than 50 mPa · s, it may sag when applied, and if it exceeds 2000 mPa · s, the permeability may decrease.

Each component constituting the uncured acrylic resin of the present invention (hereinafter simply referred to as “acrylic resin”) will be described.
The (meth) acrylates of the present invention are monofunctional (meth) acrylates having an ethylenically unsaturated double bond in one molecule, and polyfunctional (meth) acrylates having an ethylenically unsaturated double bond in one molecule. (Meth) acrylate having no ethylenically unsaturated double bond in one molecule, and one or more of these can be used. It is particularly preferable to contain a monofunctional (meth) acrylate having a heavy bond and / or a polyfunctional (meth) acrylate having an ethylenically unsaturated double bond in one molecule.

Examples of the monofunctional (meth) acrylate having an ethylenically unsaturated double bond in one molecule include (meth) acrylate having an allyl group such as allyl (meth) acrylate, (meth) acrylate having a dicyclopentenyl group, and the like. (Meth) acrylate having a dicyclopentenyl group is preferable from the viewpoint of safety and adhesiveness.
Polyfunctional (meth) acrylates having an ethylenically unsaturated double bond in one molecule include methacryl-modified liquid polybutadiene at both ends, acryl-modified liquid polyacrylonitrile butadiene at both ends, methacryl-modified liquid partially hydrogenated polybutadiene at both ends, and both ends. Acrylic-modified liquid polybutadiene and the like can be mentioned. Among these, butadiene-based oligomers whose both ends are (meth) acryl-modified are preferred in terms of adhesiveness.

  (Meth) acrylate having no ethylenically unsaturated double bond in one molecule includes (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate , 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopenta Nyl (meth) acrylate, isobornyl (meth) acrylate, methoxylated cyclodecatriene (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl Pyr (meth) acrylate, 4-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, alkyloxypolyethylene glycol mono (meth) acrylate, alkyloxypolypropylene glycol mono (meth) acrylate , Phenoxypolyethylene glycol mono (meth) acrylate, phenoxypolypropylene glycol mono (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, glycidyl (meth) acrylate, caprolactone modified tetrahydrofur Furyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, N , N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, morpholine (meth) acrylate, ethoxycarbonylmethyl (meth) acrylate, ethylene oxide modified phthalic acid (Meth) acrylate, ethylene oxide-modified succinic acid (meth) acrylate, trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, 2-hydroxy-3- (meth) acryloyloxypropylmethylammonium chloride, polyethylene glycol di ( (Meth) acrylate, polyglycerol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate, 1, -Butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol Hexa (meth) acrylate, tris (meth) acryloyloxyethyl isocyanurate, 2,2-bis (4- (meth) acryloxyphenyl) propane, 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane 2,2-bis (4- (meth) acryloxypropoxyphenyl) propane, 2-bis (4- (meth) acrylotetraethoxyphenyl) propane, epoxy acrylate, urethane acrylate, etc., one of these Or 2 It is possible to use more than.

As the polymerization initiator of the present invention, one having a function of a radical polymerization initiator can be used. Examples thereof include organic peroxides and azo compounds.
Examples of the organic peroxide include the following. Ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, etc. Peroxyketals, hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, alkyl peroxides such as dicumyl peroxide, t-butylcumyl peroxide, isobutyl peroxide, acetyl peroxide, etc. Acyl peroxides, peroxydicarbonates such as diisopropyl peroxydicarbonate, and peroxyesters such as t-butyl peroxyacetate.
Examples of the azo compound include the following. Azonitrile compounds such as azoisobutyronitrile, azoamidine compounds such as 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis {2-methyl-normal- [1,1 Azoamide compounds such as -bis (hydroxymethyl) -2-hydroxyethyl] propionamide} and alkylazo compounds such as 2,2'-azobis (2,2,4-trimethylpentane).
One or two or more of these can be used as the polymerization initiator, but the use of an organic peroxide is preferable in terms of adhesiveness and curability.

The decomposition accelerator of the present invention functions to promote the decomposition of the polymerization initiator, and examples thereof include thiourea derivatives, amines, metal salts of organic acids, and organic metal chelate compounds. Examples of the thiourea derivative include diethyl thiourea, dibutyl thiourea, and ethylene thiourea. Examples of amines include N, N-diethyl-p-toluidine, N, N-dimethyl-p-toluidine, triethylamine, ethylenediamine, ethyldiethanolamine and the like. Examples of the metal salt of an organic acid include cobalt naphthenate, copper naphthenate, zinc naphthenate, cobalt octylate, iron octylate and the like.
Examples of the organometallic chelate compound include copper acetylacetonate, manganese acetylacetonate, iron acetylacetonate, and cobalt acetylacetonate.
As the decomposition accelerator, one or more of these can be used, but the use of an organic metal salt and / or an organic metal chelate compound is preferable in terms of excellent curability and adhesiveness on a wet surface.

  The acrylic resin of the present invention includes a polymerization inhibitor, a colorant, a solvent, a rust inhibitor, a thickener, a paraffin, a silane coupling agent, a chelating agent, a dye, and a pigment as long as the object of the present invention is not impaired. Various additives such as flame retardants, surfactants, inorganic fillers typified by calcium carbonate and silica can be used in combination.

The method for forming the acid-resistant composite of the present invention is not particularly limited. For example, water is added to a hydraulic material and the mixture is kneaded with a mixer, and the obtained kneaded product is troweled, sprayed, or grouted. By any method such as construction method, it is handed over to the place where the deteriorated part of the concrete is removed and cured. Furthermore, there is a method in which a two-pack type acrylic resin is applied to the cured surface using a brush, a roller, or the like.
In the present invention, after applying an acrylic resin to a cured body layer of a hydraulic material, various putty-like high-curing curable resin compositions, plate-shaped molded products, net-shaped molded products, cement compositions, etc. It may be covered with.

  After adding water and kneading to a hydraulic material containing alumina cement at the mixing ratio shown in Table 1, it is packed in a 4 × 4 × 16 cm mold and cured in air at 20 ° C. for one day before demolding did. On the surface of the cured body, an acrylic resin was applied to the entire surface with a brush (number of coatings: once) and the acrylic resin was cured to obtain a test body. The hardening porosity of the hydraulic material containing alumina cement (those not coated with acrylic resin), the penetration depth of the acrylic resin, and immersion in a 5 mass% sulfuric acid aqueous solution for 28 days were measured for the sulfuric acid penetration depth. For comparison, the same procedure was performed for the case where an epoxy resin was used instead of the acrylic resin, the case where no acrylic resin was applied, and the case where ordinary Portland cement was used instead of alumina cement. The results are shown in Table 2.

(Materials used)
Cement: manufactured by Denki Kagaku Kogyo Co., Ltd., ordinary Portland cement Alumina cement: manufactured by Denki Kagaku Kogyo Co., Ltd., Alumina cement No. 1 blast furnace slag: granulated blast furnace slag, commercially available product, Blaine specific surface area 6100 cm ² / g
Aggregate: Silica sand, maximum particle size 2.5 mm, commercial product lightweight aggregate: light aggregate manufactured by firing obsidian, maximum particle size 1.5 mm, commercial product air entrainer: long chain olefin sulfonate, Commercially available acrylic resin A: monofunctional (meth) acrylate (methacrylate having a dicyclopentenyl group) having an ethylenically unsaturated double bond in one molecule and ethylenically unsaturated double bond in one molecule Acrylic resin containing polyfunctional (meth) acrylate (both ends methacryl-modified liquid polybutadiene), manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Hard Rock II, DK550-003”, viscosity 300 mPa · s, mixing ratio A liquid (polymerization start) Agent: Contains cumene hydroperoxide): Liquid B (decomposition accelerator: contains cobalt octylate) = 1: 1, number of coatings once acrylic resin B: 1 molecule An acrylic resin containing a monofunctional (meth) acrylate having a ethylenically unsaturated double bond (methacrylate having a dicyclopentenyl group), manufactured by Denki Kagaku Kogyo Co., Ltd., trade name “Hard Rock II, DK530-005” , Viscosity 500 mPa · s, mixing ratio liquid A (polymerization initiator: containing cumene hydroperoxide): liquid B (decomposition accelerator: containing cobalt octylate) = 1: 1, number of coatings once acrylic resin C: 1 Monofunctional (meth) acrylate having an ethylenically unsaturated double bond in the molecule (methacrylate having a dicyclopentenyl group) and (meth) acrylate having no ethylenically unsaturated double bond in one molecule (2 -Acrylic resin containing ethylhexyl methacrylate), manufactured by Denki Kagaku Kogyo Co., Ltd., trade name "Hard Rock II, DKP-63 ”, Viscosity 1000 mPa · s, mixing ratio A liquid (polymerization initiator: containing cumene hydroperoxide): B liquid (decomposition accelerator: containing cobalt octylate) = 1: 1, number of coating times epoxy resin A: Modified polyamidoamine-based curing agent system, commercial product, viscosity: 9000 mPa · s, mixing ratio A liquid (main agent): B liquid (curing agent) = 4: 1, once applied epoxy resin B: modified polyamidoamine-based curing agent System (low viscosity type), commercial product, viscosity: 950 mPa · s, mixing ratio A liquid (main agent): B liquid (curing agent) = 2: 1, number of applications once

(Measuring method)
Porosity: It was calculated | required based on ASTM-C-642 about the test body of the hardening body of the hydraulic material which has not apply | coated the acrylic resin 1 day after mold release.
Penetration depth of acrylic resin: After the acrylic resin was applied to the specimen and the acrylic resin was cured, the specimen was cut with a cutter, and the cut surface was observed with a scanning electron microscope to obtain the penetration depth.
Sulfuric acid penetration depth: A cured material of a hydraulic material containing alumina cement or a test body on which an acrylic resin has been cured by applying an acrylic resin is immersed in a 5% by mass sulfuric acid aqueous solution at a temperature of 20 ° C. for 28 days. The penetration depth was measured. The penetration depth was determined by the phenolphthalein method.

  From Table 2, it can be seen that the acid-resistant composite material of the present invention is excellent in acid resistance without permeation of sulfuric acid. When ordinary cement is used, the penetration of sulfuric acid has a part that penetrates and a part that does not. Compared to the case using alumina cement (Experiment No. 1-15 to 1-21 and Experiment No. 1 23-1-26), and the sulfate ion shielding performance was slightly low. In addition, a sample having a porosity exceeding 50% by volume (Experiment No. 1-22) permeated too much after one coating, and the acrylic resin content did not remain on the surface layer portion. Further, when the epoxy resin was applied (Experiment Nos. 1-31 to 1-34), coating unevenness occurred, and permeation of sulfate ions was observed from the uncoated part.

  A hydraulic material prepared by blending silica fume and / or fly ash with the amount shown in Table 3 with respect to 100 parts by mass of the alumina cement or the cement of No. 13 and No. 13 of Example 1 in an internal ratio. Was prepared, a cured body layer was formed, acrylic resin A was applied, and the test was performed in the same manner as in Example 1. The results are shown in Table 3.

(Materials used)
Silica fume: Commercial product, density 2.19 g / cm ³ , specific surface area 2 × 10 ⁵ cm ² / g
Blast furnace slag: Commercial product, density 2.92 g / cm ³ , specific surface area 6000 cm ² / g

  From Table 3, it can be seen that the acid-resistant composite material of the present invention is excellent in acid resistance without permeation of sulfuric acid even when silica fume and / or fly ash is contained.

  After adding water and kneading to the hydraulic materials of the formulation No. 2, No. 7, No. 10, No. 12 of Example 1 in the same manner as in Example 1, the length 30 cm × width 30 cm × thickness 6 cm. A concrete flat plate was applied with a trowel so as to have a thickness of 1 cm, and after curing (after air curing for 12 hours), the acrylic resin of Example 1 was applied (twice). The adhesion strength was measured 1 day after application. The results are shown in Table 4. For comparison, the adhesion strength was measured in the same manner when the epoxy resins A and B of Example 1 were applied (twice) and when ordinary Portland cement was used.

(Measuring method)
Adhesion strength: A concrete cutter was used to cut the cut surface with a concrete cutter so that the surface of the concrete coated with acrylic resin was a 4 × 4 cm square, and measured with a Kenken-type adhesion tester.

  From Table 4, it can be seen that the acid-resistant composite material of the present invention is excellent in adhesion strength between the cured body of the hydraulic material and the applied acrylic resin. Compared with hardened body of alumina cement (mixture No.2, No.7) in case of hardened body of normal Portland cement (mixture No.10, No.12) (Experiment No.3-1, 3-2) And Experiment No.3-3, 3-4, Experiment No.3-5, 3-6 and Experiment No.3-7, 3-8, Experiment No.3-9, 3-10 and Experiment No.3- 11 and 3-12), the adhesion strength with the acrylic resin is slightly reduced. When the epoxy resin is applied (Experiment Nos. 3-13 to 3-20), the adhesion strength with the cured body of the hydraulic material is lower than that of the acrylic resin.

  In the same manner as in Example 1, a cured material (4 × 4 × 16 cm) of the hydraulic material having the composition No. 7 in Table 1 was prepared, and the penetration depth of sulfuric acid was changed for the acrylic resin and epoxy resin applied times. It was confirmed. The results are shown in Table 5.

  From Table 5, it can be seen that the acid-resistant composite material of the present invention has no permeation of sulfuric acid and is excellent in acid resistance.

The hydraulic materials of Formulation No. 2 and Formulation No. 7 of Example 1 were kneaded and applied with a trowel to the waterway wall surface of the sewage treatment plant, and after curing, the acrylic resin of Example 1 was applied once with a roller. For comparison, the case where the acrylic resin was not applied and the case where the epoxy resins A and B were applied were also performed. One year later, the surface condition of the construction site was observed, and a portion was sampled with a core drill to measure the sulfuric acid penetration depth. The average hydrogen sulfide concentration for one year at the construction site was about 10 ppm.
As a result, the surface state of the cured body (acid-resistant composite) coated with the acrylic resin of the present invention was hardly changed from one year ago, and the sulfuric acid penetration depth was 0 mm. On the other hand, the cured body to which nothing was applied had a sulfuric acid penetration depth of 0.8 mm, although the surface state was hardly changed. In addition, when the epoxy resins A and B were applied, there was a trace that the sulfate ions had permeated from the pinhole, and the epoxy resin A had a maximum sulfate ion penetration depth of 0.7 mm for a single application, and 0. As for 3 mm and the epoxy resin B, the maximum sulfate ion penetration depth was 0.5 mm for the first coating and 0.1 mm for the second coating.

  The acid-resistant composite of the present invention has better acid resistance than ordinary concrete and mortar, and unlike conventional resins, it does not need to be applied in several layers and can be repaired efficiently. Therefore, it can be used widely in the field of concrete structures such as sewage treatment facilities.

Claims (4)

An acid-resistant composite comprising a hydraulic material containing alumina cement and blast furnace slag and a cured material layer having a porosity of 10 to 50% by volume and a cured material layer of an acrylic resin having a viscosity of 100 to 500 mPa · s.   The acid-resistant composite according to claim 1, wherein the cured body layer of the hydraulic material contains silica fume and / or fly ash. The cured body layer of the acrylic resin is a monofunctional (meth) acrylate having an ethylenically unsaturated double bond in one molecule and / or a polyfunctional (meth) acrylate having an ethylenically unsaturated double bond in one molecule. The acid-resistant composite according to claim 1 or 2, which is obtained by polymerizing a liquid mainly composed of (meth) acrylates containing a polymerization initiator, a polymerization initiator, and a decomposition accelerator. A method for repairing concrete, wherein the acid-resistant composite according to any one of claims 1 to 3 is formed on a concrete surface.