JP5085015B2 - Anticorrosive composite and process for producing the same - Google Patents

Description

  The present invention mainly relates to an anticorrosive composite used in the field of civil engineering and architecture.

  In the present invention, “parts” and “%” are based on mass unless otherwise specified.

In recent years, deterioration cases of concrete structures due to sulfuric acid are increasing mainly in sewage treatment facilities. Against this background, more research on sulfuric acid deterioration of concrete has been seen than ever before. As a countermeasure against sulfuric acid deterioration, a method of coating a resin having excellent acid resistance or a method of repairing a cross section with acid-resistant mortar is employed.
As acid-resistant mortar, mortar in which a large amount of blast furnace slag, fly ash, silica fume, and the like are mixed with Portland cement has been proposed (Patent Document 1).
On the other hand, alumina cement is known along with Portland cement. Alumina cement is a hydraulic material mainly composed of a calcium aluminate compound. Compared with Portland cement, calcium aluminate compounds are superior in initial strength development and have excellent characteristics such as resistance to chloride penetration and acid resistance, but long-term strength due to hydrate conversion (conversion). As a method for preventing the decrease, a method in which blast furnace granulated slag, fly ash, silica fume and the like are used in combination has been proposed (Patent Documents 2 and 3).
In addition, shrinkage reducing agents have been developed to prevent cracking. As a method of using the shrinkage reducing agent, a method of mixing with cement or a method of applying cement concrete after hardening is known, and a concrete composition obtained by kneading a hydraulic composition, water, and a shrinkage reducing agent is used. In addition, a method of forming an evaporation suppression coating layer has been proposed (Non-Patent Document 1, Patent Document 4). Furthermore, a sealing agent for curing containing an ethylene-vinyl acetate copolymer emulsion which is sprayed or applied to the concrete surface to coat the concrete surface has also been proposed (Patent Document 5).

Japanese Unexamined Patent Publication No. 2000-128618 JP-A-60-180945 Japanese Patent Laid-Open No. 01-141844 JP 2002-193686 A Japanese Patent Publication No.62-000116 Expansion material and shrinkage reducing agent, concrete engineering, Vol.24, No.2, Feb 1986, p.56-62

  As a result of various studies on an anticorrosive composite that has both excellent acid resistance and crack resistance, does not float or peel off the coating layer, and has excellent adhesion, the present inventors have found that the calcium aluminate compound and It was discovered that by applying a shrinkage reducing agent to the surface of mortar or concrete containing blast furnace granulated slag fine powder, an anticorrosive composite capable of solving the above problems can be obtained, and the present invention has been completed. It was.

That is, the present invention is a calcium aluminate compound having a CaO / Al ₂ O ₃ molar ratio of 1 to 2 and a Blaine specific surface area of 3000 to 9000 cm ² / g and a Blaine specific surface area of 3000 to 9000 cm ² / g. and also contains a water-granulated blast furnace slag, calcium aluminate compound and blast furnace slag total of 100 parts by weight of fine powder, calcium aluminate compounds 30-50 parts by weight, granulated blast furnace slag fine powder 50 200 to 500 g / shrinkage reducing agent having a low molecular weight ethylene oxide and propylene oxide copolymer as a component or a lower alcohol alkylene adduct as a component on the surface of mortar or concrete having a mass of 70 parts by mass m ² and coated anticorrosive complexes, mortar or concrete hula The anticorrosive composite containing at least one of ash, silica fume, pulp sludge incineration ash, sewage sludge incineration ash, and waste glass powder, and the mortar or concrete contains a polymer and / or a fibrous material A calcium aluminate compound having a CaO / Al ₂ O ₃ molar ratio of 1 to 2 and a Blaine specific surface area of 3000 to 9000 cm ² / g and a Blaine specific surface area of 3000 to 9000 cm. ^{2 /} g and also contains a water-granulated blast furnace slag is a calcium aluminate-based compound and the total of 100 parts by weight of water-granulated blast furnace slag, calcium aluminate compounds 30-50 parts by weight, blast furnace water low molecular weight ethylene oxa on the surface of the concrete is a granulated slag from 50 to 70 parts by weight A method of de as a copolymer component of propylene oxide or it is an ingredient alkylene adduct of a lower alcohol shrinkage reducing agent 200-500 g / m ² coatings anticorrosive complex.

  The anticorrosive composite of the present invention has excellent acid resistance and crack resistance, and has effects such as no swelling and peeling, and excellent adhesion.

The calcium aluminate compound of the present invention is a generic term for compounds mainly composed of CaO and Al ₂ O ₃ and is not particularly limited. Specific _{examples, CaO · 2Al 2 O 3,} CaO · Al 2 O 3, 12CaO · 7Al 2 O 3, 11CaO · 7Al 2 O 3 · CaF 2, 3CaO · Al 2 O 3, 3CaO · 3Al 2 O 3 -Crystalline calcium aluminates represented as CaSO _{4 and the} like, and amorphous compounds mainly composed of CaO and Al ₂ O ₃ components. Among these, it is preferable from the viewpoint of securing the pot life to select one having a CaO / Al ₂ O ₃ molar ratio of 1 to 2.

Examples of a method for obtaining a calcium aluminate compound include a method in which a CaO raw material and an Al ₂ O ₃ raw material are heat-treated with a rotary kiln or an electric furnace. Examples of the CaO raw material for producing the calcium aluminate compound include calcium carbonate such as limestone and shells, calcium hydroxide such as slaked lime, and calcium oxide such as quick lime. Examples of the Al ₂ O ₃ raw material include aluminum by-products in addition to industrial by-products called bauxite and aluminum residue ash.

When a calcium aluminate compound is obtained industrially, impurities may be contained. Specific examples thereof include SiO ₂ , Fe ₂ O ₃ , MgO, TiO ₂ , MnO, Na ₂ O, K ₂ O, Li ₂ O, S, P ₂ O ₅ , and F. The presence of these impurities is not particularly problematic as long as the object of the present invention is not substantially impaired. Specifically, there is no particular problem if the total of these impurities is in the range of 10% or less.

Further, as the impurity compounds, calcium alumino ferrite etc. _{4CaO · Al 2 O 3 · Fe} 2 O 3, 6CaO · 2Al 2 O 3 · Fe 2 O 3, 6CaO · Al 2 O 3 · 2Fe 2 O 3, 2CaO · Calcium ferrites such as Fe ₂ O ₃ and CaO · Fe ₂ O ₃ , galenite 2CaO · Al ₂ O ₃ · SiO ₂ , calcium aluminosilicates such as anorthite CaO · Al ₂ O ₃ · 2SiO ₂ , melvinite 3CaO · MgO · 2SiO _2, Akerumanaito 2CaO · MgO · 2SiO _2, calcium magnesium silicate, such as Monte celite CaO · MgO · SiO _2, tri-calcium silicate 3CaO · SiO _2, dicalcium silicate 2CaO · SiO _2, rankinite night 3CaO · 2 in some cases iO _2, calcium silicates, such as wollastonite CaO · SiO _2, calcium titanate CaO · TiO _2, free lime, leucite _{(K 2 O, Na 2 O} ) , etc. · _{Al 2} O 3 · SiO 2 . In the present invention, these crystalline or amorphous materials may be mixed.

The particle size of the calcium aluminate compound of the present invention is not particularly limited, but is usually in the range of 3000 to 9000 cm ² / g in terms of Blaine specific surface area, more preferably about 4000 to 8000 cm ² / g. . If it is less than 3000 cm ² / g, strength development may not be sufficient, and if it exceeds 9000 cm ² / g, handling may be difficult.

The ground granulated blast furnace slag of the present invention bears the effect of preventing strength reduction due to conversion of calcium aluminate compounds and acid resistance. The fineness of the granulated blast furnace slag powder is not particularly limited, but is usually in the range of about 3000 to 9000 cm ² / g in terms of the specific surface area of Blaine.

In the present invention, pozzolanes can be used in addition to latent hydraulic materials such as ground granulated blast furnace slag. Pozzolana plays a role of promoting the effect of preventing the strength reduction due to the conversion of the calcium aluminate compound and the effect of improving the acid resistance. The pozzolan is not particularly limited, and examples include fly ash, silica fume, pulp sludge incineration ash, sewage sludge incineration ash, and waste glass powder. Among these, use of fly ash or silica fume is preferable.
The fineness of fly ash and silica fume is not particularly limited. Usually, fly ash has a brain specific surface area of about 3000 to 9000 cm ² / g, and silica fume has a BET specific surface area. In the range of about 2 to 200,000 m ² / g.

The blending ratio of the calcium aluminate compound of the present invention and ground granulated blast furnace slag (hereinafter referred to as cement composition) is not particularly limited, but usually the calcium aluminate compound is 30 to 80 parts. Yes, 50 to 70 parts are preferable, and the granulated blast furnace slag powder is 20 to 70 parts, preferably 30 to 50 parts.
Moreover, pozzolana can be used by substituting with a part of ground granulated blast furnace slag as needed. If the calcium aluminate compound is less than 30 parts or the granulated blast furnace slag powder exceeds 70 parts, the strength development may not be sufficient, the calcium aluminate compound may exceed 90 parts, or the blast furnace When the granulated slag fine powder is less than 10 parts, strength reduction due to conversion may occur or sufficient acid resistance may not be obtained.

The shrinkage reducing agent of the present invention is used for applications such as drying shrinkage prevention and curing shrinkage compensation, and is not particularly limited.For example, it is a kind of nonionic surfactant, It is a liquid or powder that dissolves in water in the pores of the hardened cement body and has a function of reducing the surface tension of water when it evaporates.
The basic structure of the shrinkage reducing agent has a polyoxyalkylene polymer, and a lower alcohol, phenol, and amino bond are added to the terminal.
Specifically, polypropylene glycol, ethylene oxide methanol adduct ethylene oxide / propylene oxide block polymer, ethylene oxide / propylene oxide random polymer, glycol cycloalkyl group adduct, glycol adducts with methyl groups added to both ends of glycol, glycol A phenyl group adduct, a block polymer obtained by adding a methylphenyl group to glycol, an adduct obtained by adding ethylene oxide methanol to both ends of glycol, an adduct obtained by adding dimethylamine to glycol, or the like can be used.

The shrinkage reducing agent is sprayed before the set mortar or concrete is cured. The dilution ratio of the shrinkage reducing agent is preferably 10 times or less. If it exceeds 10 times, the crack prevention effect may not be obtained.
The method of spraying the shrinkage reducing agent is not particularly limited as long as it is a method of uniformly dispersing on the mortar or concrete surface, and there is a method of using a sprayer, a sprayer, a watering can, etc. depending on the construction area.

Although the usage-amount of a shrinkage | contraction reducing agent is not specifically limited, It is preferable to use in the range of 100-500g per 1 m < ² > in conversion of a stock solution, and 150-400g is more preferable. If it is less than 100 g, the effect of improving crack resistance and the effect of improving acid resistance are not sufficient, and even if it exceeds 500 g, further improvement of the effect cannot be expected.

In the present invention, blending a polymer with mortar or concrete is preferable from the viewpoint of improving acid resistance and from the viewpoint of improving adhesion strength.
The polymer of the present invention is not particularly limited. The polymers are roughly classified into four types: aqueous polymer dispersions, water-soluble polymers, liquid polymers, and re-emulsifying powder resins. Specific examples of the aqueous polymer dispersion include natural rubber latex, synthetic rubber latex, resin emulsion, and mixed dispersion. Among these, styrene butadiene rubber, chloroprene rubber, methyl methacrylate butadiene rubber, acrylonitrile butadiene rubber, polyacrylate, ethylene vinyl acetate, styrene acrylate, vinyl polypropionate, polypropylene, epoxy resin, asphalt, paraffin, Examples include mixed latex and mixed emulsion. Examples of the water-soluble polymer include methyl cellulose, hydroxypropyl methyl cellulose, polyvinyl alcohol, calcium acrylate, magnesium acrylate and the like. Examples of the liquid polymer include unsaturated polyester resins and epoxy resins. Examples of the re-emulsifying powder resin include styrene butadiene rubber, ethylene vinyl acetate, vinyl acetate vinyl versatate, styrene acrylate ester, polyacrylate ester and the like.

  Although the usage-amount of a polymer is not specifically limited, Usually, 1-10 parts are preferable in conversion of solid content with respect to 100 parts of cement compositions, and 3-7 parts are more preferable. If the amount is less than 1 part, the effect of improving the adhesion strength, the substance barrier property and the crack resistance may not be sufficiently obtained. If the amount exceeds 10 parts, the setting delay and the initial strength may be deteriorated.

  In the present invention, it is preferable to add a fibrous material to mortar or concrete from the viewpoint of improving crack resistance. The fibrous material referred to in the present invention is not particularly limited, and examples thereof include organic fibers such as vinylon fibers, cellulose fibers, and acrylic fibers, carbon fibers, steel fibers, wollastonite fibers, and glass fibers. An inorganic fiber etc. are mentioned. In the present invention, at least one of these can be used.

  Although the usage-amount of a fibrous substance is not specifically limited, Usually, 0.1-3 parts are preferable with respect to 100 parts of cement compositions, and 0.3-2 parts are more preferable. If it is less than 0.1 part, crack resistance may not be sufficiently obtained, and even if it is used in excess of 3 part, further enhancement of the effect cannot be expected, and dispersibility may deteriorate.

  In the present invention, a known cement may be used in combination with the cement composition of the present invention. As well-known cements, various portland cements such as normal, early strength, super early strength, low heat, and moderate heat, various mixed cements obtained by mixing blast furnace slag, fly ash, or silica with these portland cements, limestone powder, Examples include filler cement mixed with blast furnace slow-cooled slag fine powder, waste-use cement, so-called eco-cement, and one or more of these can be used in combination.

  In the mortar or concrete of the present invention, in addition to aggregates such as sand and gravel, fine limestone powder, ground granulated blast furnace slag, water reducing agent, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent, antifoaming At least one of an agent, a thickener, a rust inhibitor, an antifreeze agent, a coagulation modifier, a clay mineral such as bentonite, and an anion exchanger such as hydrotalcite is substantially used for the purpose of the present invention. It is possible to use in the range which does not inhibit.

  In the present invention, the mixing method of each material is not particularly limited, and the respective materials may be mixed at the time of construction, or a part or all of them may be mixed in advance.

  Any existing device can be used as the mixing device, and for example, a tilting barrel mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a Nauta mixer can be used.

  Examples will be described in detail below.

"Example 1"
A calcium aluminate compound and ground granulated blast furnace slag were blended as shown in Table 1 to prepare a cement composition. Next, mortar was prepared according to JIS R 5201, and shrinkage reducing agent i or shrinkage reducing agent B was applied to the surface at a rate of 200 g per 1 m ² . Confirmation of crack resistance of the cured body, observation of swelling and peeling of the mortar, and acid resistance test were performed. For comparison, the same procedure was performed when ordinary Portland cement was used instead of the cement composition of the present invention, and when a shrinkage reducing agent was mixed with mortar instead of being applied to the surface. . The results are also shown in Table 1.

<Materials used>
Calcium aluminate compound (1): Commercially available alumina cement, manufactured by Denki Kagaku Kogyo KK, as a main component CaO · _Al 2 _{O 3,} Blaine specific surface area of 5000 cm ² / g
Calcium aluminate compound (2): 12CaO.7Al ₂ O ₃ , reagent grade calcium carbonate and aluminum oxide are mixed at a molar ratio of 12 to 7 and baked at 1350 ° C. for 3 hours twice. Synthesis, Blaine specific surface area 5000 cm ² / g
Calcium aluminate compound (3): Amorphous 12CaO · 7Al ₂ O ₃ , 3% reagent grade silica added to calcium aluminate (2), melted at 1650 ° C., rapidly cooled, synthesized, and brain Specific surface area 5000 cm ² / g
Calcium aluminate compound (4): mixture of equal amounts of calcium aluminate (1) and calcium aluminate (2), Blaine specific surface area of 5000 cm ² / g
Granulated blast furnace slag powder: manufactured by Kanto Sement Co., Ltd., Blaine specific surface area 4000 cm ² / g
Shrinkage reducing agent a: Commercially available shrinkage reducing agent comprising a copolymer of low molecular weight ethylene oxide and propylene oxide b: Commercially available product comprising an alkylene adduct of a lower alcohol as a component Normal Portland cement: Three types of commercially available products, etc. Water: Tap water Fine aggregate: Standard sand used in JIS R 5201

<Measurement method>
Crack resistance test: A mortar was applied to a 50 cm × 50 cm concrete plate with a thickness of 10 mm, and left for 1 day in an environment of a temperature of 20 ° C. and a relative humidity of 40%, and the occurrence of cracks was observed. ◎ has no cracks. ○ indicates that only one crack with a crack width of 0.05 mm or less occurs. -Indicates one crack, but if the crack width exceeds 0.05 mm, Δ indicates two cracks. ×: 3 or more cracks occurred.
Acid resistance: The specimen was immersed in a 7% strength sulfuric acid solution for 3 months, and the acid resistance was evaluated from the change in appearance and mass reduction of the specimen. × indicates a significant change in appearance and a mass change rate of ± 5% or more, △ indicates a significant change in appearance, or a mass change rate satisfies ± 5% or more, ○ Both the change in appearance and the change in mass were determined not to meet the above conditions.
Observation of swelling / peeling: When the above acid resistance test shows visible swelling and peeling occurs on the cured body surface, x, swelling or peeling is observed △, where none was recognized and was in a healthy state.

  From Table 1, it can be seen that the anticorrosive composite of the present invention has excellent acid resistance and crack resistance, and there is no swelling or peeling.

"Example 2"
As in Example 1, except that 50 parts of calcium aluminate compound (1), 40 parts of granulated blast furnace slag powder and 10 parts of various pozzolans were blended as shown in Table 2 to obtain a cement composition. went. The results are also shown in Table 2.

<Materials used>
Pozzolana A: Commercial fly ash, Blaine specific surface area 4000 cm ² / g
Pozzolana B: Commercially available silica fume, BET specific surface area of 15 m ² / g
Pozzolana C: Commercially available pulp sludge incineration ash, Blaine specific surface area 4000 cm ² / g
Pozzolana D: Commercial sewage sludge incineration ash, Blaine specific surface area 9000 cm ² / g
Pozzolana E: Commercially available waste glass powder, Blaine specific surface area 4000 cm ² / g
Pozzolanic F: Equivalent mixture of pozzolanic substance A and pozzolanic substance B, Blaine specific surface area 14000 cm ² / g

  From Table 2, it can be seen that the anticorrosive composite of the present invention has excellent acid resistance and resistance to cracking, and there is no swelling or peeling.

"Example 3"
A cement composition containing 50 parts of calcium aluminate compound (1), 40 parts of granulated blast furnace slag powder and 10 parts of pozzolana F was used, and the amount of coating curing agent changed as shown in Table 3. Except that, the same procedure as in Example 1 was performed. The results are also shown in Table 3.

  From Table 3, it can be seen that the anticorrosive composite of the present invention has excellent acid resistance and crack resistance, and there is no swelling or peeling.

Example 4
50 parts of calcium aluminate compound (1), 40 parts of ground granulated blast furnace slag and 10 parts of pozzolanic F are blended, and the polymer is converted into solids as shown in Table 4 with respect to 100 parts in total. The same procedure as in Example 1 was performed except that the cement composition was formulated. An adhesion test was also conducted. The results are also shown in Table 4.

<Materials used>
Polymer α: Commercially available styrene butadiene rubber polymer polymer β: Commercially available polyacrylate polymer polymer γ: Commercially available ethylene vinyl acetate polymer polymer Δ: Commercially available vinyl vinyl acetate polymer

<Measurement method>
Adhesion test: According to JIS A 1171, the adhesion strength at the age of 28 days was measured.

  From Table 4, it can be seen that the anticorrosive composite of the present invention has excellent acid resistance and crack resistance, does not swell or peel, and has high adhesion strength.

"Example 5"
50 parts of calcium aluminate compound (1), 40 parts of ground granulated blast furnace slag and 10 parts of pozzolana F were blended, and a fibrous material was blended as shown in Table 5 with respect to 100 parts in total. Except that, the same procedure as in Example 1 was performed. The results are also shown in Table 5.

<Materials used>
Fibrous material a: commercially available vinylon fiber, length 6 mm, diameter 200 μm
Fibrous material b: commercially available acrylic fiber, length 6 mm, diameter 200 μm
Fibrous material c: commercially available cellulose fiber, length 200 μm, diameter 30 μm
Fibrous material d: commercially available carbon fiber, length 6 mm, diameter 200 μm
Fibrous material e: commercially available wollastonite fiber, length 600 μm, diameter 40 μm

  From Table 5, it can be seen that the anticorrosive composite of the present invention has excellent acid resistance and crack resistance, and there is no swelling or peeling.

  The anticorrosive composite of the present invention has both excellent acid resistance and crack resistance, and is suitable for civil engineering and construction applications because it does not swell or peel off and has excellent adhesion.

Claims (5)

CaO / _Al 2 _{O 3} molar ratio of 1 to 2, water-granulated blast furnace slag is 3000~9000cm ² / g calcium aluminate compound and Blaine specific surface area is 3000~9000cm ² / g in Blaine specific surface area And a total of 100 parts by mass of calcium aluminate compound and ground granulated blast furnace slag, 30 to 50 parts by mass of calcium aluminate compound and 50 to 70 parts by mass of granulated blast furnace slag powder. Anti-corrosion property of mortar or concrete surface coated with 200-500 g / m ² shrinkage reducing agent containing low molecular weight ethylene oxide and propylene oxide copolymer or lower alcohol alkylene adduct Complex. The anticorrosive composite according to claim 1, wherein the mortar or concrete contains at least one of fly ash, silica fume, pulp sludge incineration ash, sewage sludge incineration ash, and waste glass powder. The anticorrosive composite according to claim 1 or 2, wherein the mortar or concrete contains a polymer. The anticorrosive composite according to any one of claims 1 to 3, wherein the mortar or concrete contains a fibrous substance. CaO / _Al 2 _{O 3} molar ratio of 1 to 2, water-granulated blast furnace slag is 3000~9000cm ² / g calcium aluminate compound and Blaine specific surface area is 3000~9000cm ² / g in Blaine specific surface area And a total of 100 parts by mass of calcium aluminate compound and ground granulated blast furnace slag, 30 to 50 parts by mass of calcium aluminate compound and 50 to 70 parts by mass of granulated blast furnace slag powder. An anticorrosive composite comprising a concrete surface coated with a shrinkage reducing agent comprising 200 to 500 g / m ² of a low molecular weight ethylene oxide / propylene oxide copolymer or a lower alcohol alkylene adduct as a component. The manufacturing method.