JP4642650B2 - Surface coated mortar or concrete - Google Patents

Description

  The present invention mainly relates to a surface-coated mortar or concrete used in the civil engineering and construction industry and capable of neutralization and suppression of salt damage.

When carbon dioxide in the air penetrates into mortar or concrete, the alkalinity is lowered, so that the passive film formed on the surface of the internal reinforcing bar is destroyed and rust is generated. Due to the volume expansion of the rust, the concrete is cracked and floated, and the concrete pieces are peeled off. In particular, such a deterioration phenomenon is likely to be manifested in concrete having a large water / cement ratio or concrete having a small cover with a reinforcing bar. Further, when chloride ions permeate, the passive film of the reinforcing bar is destroyed and rust is generated, and cracks and floats are also generated in the concrete.
Therefore, various repair methods such as a surface coating method, an impregnation coating method, a cross-sectional repair method, an electrochemical repair method, etc. have been proposed for concrete subjected to neutralization and salt damage (Non-Patent Document 1). .
For example, when the neutralization does not reach the reinforcing bar position, the surface coating method or the impregnation coating method is often used. In the surface coating method, an organic resin such as an epoxy resin, an acrylic resin, or a urethane resin is applied to the concrete or mortar surface. However, these resins are very expensive materials, and it is necessary to form several layers of coating layers by applying different types of coating materials, which requires a long time for construction. The impregnation coating method is a method of modifying the surface layer portion by impregnating a concrete or mortar surface with a silane-based or silicate-based coating agent. The workability is simpler than that of a resin-based surface coating material, but the effect of suppressing the permeability of ions mediated by moisture is great, but the effect of blocking the gas such as carbon dioxide is not great.
Moreover, when deterioration is alive and cracks, floats, and the like are generated, repair work by a cross-sectional repair method is performed (Patent Documents 1 and 2). Furthermore, an organic-inorganic composite-type film curing agent has been developed (Patent Document 3), and a method of curing by applying to a hardened cement body has been proposed (Patent Document 4).

Concrete diagnosis technology '03, foundation edition, Japan Concrete Engineering Association edition, 2003, p. 236 Japanese Patent Laid-Open No. 11-270144 JP 2005-104826 A JP 2002-274976 A JP 2005-162534 A

  The present invention provides a mortar or concrete containing aluminum sulfate, the surface of which is coated with an organic-inorganic composite type coating curing agent, which can be neutralized and suppressed from salt damage.

That is, the present invention is (1) coating the surface with an organic-inorganic composite type coating curing agent containing a synthetic resin aqueous dispersion, a water-soluble resin and a swellable clay mineral having a solid content concentration of 10 to 60%. It was, comprising 0.5 to 10 parts by solid content relative to 100 parts of the cement of aluminum sulfate, mortar or concrete neutralization and salt damage is suppressed, (2) organic - inorganic composite type coating curing mortar or concrete swelling clay mineral is a synthetic fluorine mica agent (1), (3) an organic - the amount of the inorganic composite coating film curing agent is 50 to 500 g / ^{m 2} (1) or (2 ) Mortar or concrete.

  The mortar or concrete containing aluminum sulfate, the surface of which is coated with the organic-inorganic composite type film curing agent of the present invention, has an effect of suppressing neutralization and salt damage.

  Unless otherwise specified, parts and% in the present invention are shown on a mass basis.

  The mortar or concrete of the present invention is not particularly limited, and is produced using cement, sand, gravel aggregate, water or the like.

  As cement, various types of Portland cement such as normal, early strength, super early strength, moderate heat, and low heat, various mixed cements in which blast furnace slag, fly ash and fine limestone powder are mixed with these Portland cements, blast furnace slow cooling slag, Examples include filler cement mixed with limestone fine powder, and environmentally friendly cement (eco-cement) manufactured using municipal waste incineration ash and sewage sludge incineration ash as raw materials. is there. The ratio of the mixture and cement in the mixed cement is not particularly limited, and a mixture of these admixtures more than specified by JIS can be used. Furthermore, a large amount of latent hydraulic materials such as blast furnace slag fine powder, fly ash, silica fume, and pozzolanic materials may be blended in the cement.

In addition to normal sand and gravel, aggregates include natural aggregates such as silica sand and limestone, blast furnace granulated slag, blast furnace slow-cooled slag, and recycled aggregates. Can be mentioned. From the viewpoint of acid resistance and the like, it is preferable to select a silica sand system. In addition, a heavy aggregate having a specific gravity of 3.0 g / cm ³ or more can be used, and specific examples thereof include, for example, an electric furnace oxidation period slag-based aggregate, ferronickel slag, ferrochrome slag as an artificial aggregate. Non-ferrous smelted aggregates such as copper slag, zinc slag and lead slag, and natural aggregates include peridotite aggregates, so-called olivine sand, emery ore, etc. It is done. In this invention, these 1 type (s) or 2 or more types can be used together.

  The amount of water used is not particularly limited because it varies depending on the purpose / use of use and the blending ratio of each material. Usually, the water cement ratio is preferably 25 to 60%, and preferably 30 to 55% More preferred. If the water cement is less than 25%, it is difficult to obtain fluidity, and the calorific value becomes extremely large. Conversely, if it exceeds 60%, it may be difficult to ensure strength development. Moreover, mass transfer becomes easy and it tends to be difficult to ensure durability.

  Along with cement, aggregate, fluidizing agent, etc., limestone fine powder, blast furnace slow-cooled slag fine powder, sewage sludge incineration ash and its molten slag, municipal waste incineration ash and its molten slag, pulp sludge incinerated ash, etc., calcium Rapid hardening materials such as aluminate and calcium aluminate and gypsum, setting modifier, antifoaming agent, thickener, rust inhibitor, antifreeze agent, shrinkage reducing agent, steel fiber, vinylon fiber, carbon fiber, wallast One or more of fiber materials such as knight fibers, polymers, clay minerals such as bentonite, anion exchangers such as hydrotalcite, and the like are used within a range that does not substantially impair the object of the present invention. Is possible.

The aluminum sulfate of the present invention is not particularly limited, and has a chemical formula of Al ₂ (SO ₄ ) ₃ .nH ₂ O, and Al ₂ (SO ₄ ) ₃ · 14 to 18H ₂ O or Al ₂ (SO _{4) 3} · and hydrous salts such 8H ₂ O, and the like anhydrous aluminum sulfate. These can be dissolved in powder or water and added as a liquid when preparing mortar or concrete.
Aluminum sulfate is used as a hardening accelerator for mortar and concrete. Neutralization and chloride of mortar and concrete compared to the use of hardening accelerators based on other inorganic salts such as aluminates and carbonates, and hardening accelerators based on calcium aluminate. Demonstrates excellent effects of suppressing ion penetration. Therefore, it is suitable as a spraying material in tunnels and repair / reinforcement fields that are susceptible to salt damage and neutralization.
The amount of aluminum sulfate used is preferably 0.5 to 10 parts by solid content and more preferably 1 to 5 parts relative to 100 parts of cement. If the amount of aluminum sulfate used is too small, the effect of accelerating curing may not be exhibited. If it is too much, curing is too fast and a dense cured body cannot be obtained, and neutralization and penetration of chloride ions, etc. are quick. There is a case.

  The organic-inorganic composite-type film curing agent used in the present invention contains a synthetic resin aqueous dispersion, a water-soluble resin, and a swellable clay mineral. Furthermore, what contains a crosslinking agent is preferable.

The synthetic resin aqueous dispersion used in the present invention is generally a synthetic resin emulsion, an aromatic vinyl monomer, an aliphatic conjugated diene monomer, an ethylenically unsaturated fatty acid monomer, and others. The copolymerizable monomer is obtained by emulsion polymerization of one or more of these monomers. For example, styrene / butadiene latex mainly composed of styrene, styrene / acrylic emulsion, methyl methacrylate / butadiene latex copolymerized with styrene, and ethylene / acrylic emulsion. The synthetic resin emulsion is more preferably one having a carboxyl group or a hydroxy group.
Here, the emulsion polymerization is a general emulsion polymerization method in which a monomer to be polymerized is mixed, and an emulsifier, a polymerization initiator, etc. are added to the monomer and the reaction is carried out in an aqueous system.
In order to obtain blending stability with the swellable clay mineral, it is preferable to use a basic substance such as ammonia, amines, and caustic soda and adjust the pH to 5 or more.
The particle size of the synthetic resin aqueous dispersion is generally 100 to 300 nm, but preferably has a small particle size of about 60 to 100 nm.

Examples of water-soluble resins include modified starch or derivatives thereof, cellulose derivatives, saponified polyvinyl acetate or derivatives thereof, polymers having sulfonic acid groups or salts thereof, polymers or copolymers of acrylic acid or salts thereof, Examples include acrylamide polymers and copolymers, polyethylene glycol, and oxazoline group-containing polymers, and one or more of them can be used.
The water-soluble resin may be one having a solubility in pure water of 1% or more at normal temperature, and preferably 10 to 60% of hydrogen bonding groups or ionic groups per unit weight of the resin. The average molecular weight is preferably 2,000 to 1,000,000.
The amount of the water-soluble resin used is preferably 0.05 to 200 parts in terms of solid content with respect to 100 parts of solid content of the synthetic resin aqueous dispersion. If the amount is less than 0.05 parts, the moisture resistance may be lowered. If the amount exceeds 200 parts, the moisture resistance may be significantly lowered.

Examples of swellable clay minerals include layered silicate minerals belonging to the scumite genus. For example, montmorillonite, beidellite, nontronite, saponite, mica and bentonite. Any of natural products, synthetic products, and processed products can be used.
Among them, a clay mineral having a swelling power of 20 ml / 2 g or more according to a method according to the Japan Bentonite Industry Association, standard test method JBAS-104-77, particularly bentonite is preferable. Further, the ion exchange equivalent is preferably 10 milliequivalents or more, more preferably 60 to 200 milliequivalents or more per 100 g. Furthermore, the thing whose aspect ratio is 50-5,000 is preferable. The aspect ratio is the length / thickness ratio of the clay mineral dispersed in layers obtained by electron micrograph.
The amount of the swellable clay mineral used is preferably 1 to 50 parts with respect to the solid content with respect to 100 parts of the solid content of the synthetic resin aqueous dispersion. If it is less than 1 part, the moisture-proof property may be reduced and blocking may occur easily, and if it exceeds 50 parts, the film deformability of the film curing agent may be reduced.

A cross-linking agent reacts with a hydrophilic functional group such as a carboxyl group, an amide group, and a hydroxyl group contained in an aqueous dispersion of a water-soluble resin or synthetic resin to crosslink, polymerize (three-dimensional network structure), or hydrophobize. Those having an oxazoline group that undergoes an addition reaction with a carboxyl group are also preferable because they also serve as water-soluble resins.
The amount of the crosslinking agent used is preferably 0.01 to 30 parts in terms of solid content with respect to 100 parts of the total solid content of the synthetic resin aqueous dispersion and the water-soluble resin. If the amount is less than 0.01 part, the moisture resistance may be lowered. If the amount exceeds 30 parts, the moisture resistance and the anti-blocking property reach a peak.

In the present invention, a synthetic resin aqueous dispersion, a water-soluble resin, and a swellable clay mineral are mixed and further reacted with a crosslinking agent to prepare a coating film curing agent.
The method for synthesizing the coating curing agent is preferably a method in which the water-soluble resin and the swellable clay mineral are mixed in water in advance, and then the synthetic resin aqueous dispersion and the crosslinking agent are mixed. The coating film curing agent is a polymer dispersion dispersed in water, and the solid content is not particularly limited. The solid content concentration affects the strength and thickness of the film formed when applied to mortar or concrete, ease of application, and the like.
10-60% is preferable and, as for the solid content concentration of the coating agent when apply | coating to mortar or concrete, 20-50% is more preferable. If it is less than 10%, the effect of suppressing neutralization and penetration of chloride ions is not sufficient, and if it exceeds 60%, the viscosity becomes high and it becomes difficult to apply.

The coating method of the organic-inorganic composite type film curing agent is not particularly limited as long as it can form a uniform coating film, and can be distributed, applied, or sprayed. is there.
The coating amount of the organic-inorganic composite type coating curing agent is preferably used in the range of 50 to 500 g per 1 m ² , and more preferably 100 to 400 g. If the amount is less than 50 g, the effect of suppressing neutralization or penetration of chloride ions is not sufficient, and even if the amount exceeds 500 g, further improvement of the effect cannot be expected.

"Example 1"
Using a Hobart mixer with a capacity of 3L, knead for 1 minute in the mortar formulation shown in the cement physical test method (JIS R 5201), add 2 parts of aluminum sulfate to 100 parts of cement and knead again for 10 seconds. Mix and quickly mold. It was cured in the air under an environment of a temperature of 20 ° C. and a humidity of 80% for 28 days. The size of the test body is 4 × 4 × 16 cm, the side and bottom surfaces of the test body are sealed with an epoxy resin, and the coating agent having a solid content concentration shown in Table 1 is applied to the upper surface with a brush so that the solid content is 150 g / m ^2. After coating, accelerated neutralization test, chloride ion penetration test, and workability (ease of application) evaluation were performed. As a comparison, the same procedure was performed for 100 parts of cement added with 2 parts of sodium carbonate instead of aluminum sulfate. The results are shown in Table 1.

(Mortar materials and ingredients)
Cement: Ordinary Portland cement, hardening accelerator manufactured by Denki Kagaku Kogyo Co., Ltd. (A): Aluminum sulfate, reagent grade 1, anhydride hardening accelerator (B): sodium carbonate, reagent grade 1, anhydrous sand: standard sand water : Tap water cement: Sand: Water = 1: 3: 0.5 (mass ratio)
Coating agent: Organic-inorganic composite type coating curing agent, manufactured by Toagosei Co., Ltd., “CA212”, acrylic resin-fluorine mica composite type, solid content concentration 45%

(Test method)
Accelerated neutralization test: The accelerated conditions were 5% carbon dioxide concentration, 30 ° C. temperature and 60% humidity, and the coating test was applied to start the accelerated test the next day. The promotion period was 28 days, and the neutralization depth from the top surface was measured by the phenolphthalein method.
Chloride ion penetration test: The coating depth was applied and the chloride ion penetration depth was measured by immersing in simulated seawater for 28 days according to JIS A 1171 the next day.
Ease of application: When the upper surface (4 × 16 cm) of the test specimen is applied with a brush, ○ when the coating agent is uniform, Δ when the coating agent is slightly non-uniform, and the coating agent is fairly non-uniform The case was marked with x.

  Table 1 shows that the mortar containing the aluminum sulfate surface-coated with the coating agent of the present invention suppresses neutralization and salt damage.

"Example 2"
The same procedure as in Example 1 was performed except that the solid concentration was 25% and the coating amount was changed as shown in Table 2.

  Table 2 shows that the mortar containing the aluminum sulfate surface-coated with the coating agent of the present invention suppresses neutralization and salt damage and is easy to apply.

"Example 3"
The amount of aluminum sulfate added was changed as shown in Table 3, the solid content concentration of the coating agent was 25%, the coating amount was 150 g / m ^2, and the curing period until the coating agent was applied to the mortar was 1 day old The same procedure as in Example 1 was performed except that the test was performed on the 7th and 28th. The results are shown in Table 3.

  Table 3 shows that the mortar containing aluminum sulfate surface-coated with the coating agent of the present invention suppresses neutralization and salt damage.

"Example 4"
Table 4 shows the test specimens to which the coating agent in which the neutralization depth of Experiment No. 1-1 in Example 1 was 7.6 mm and the chloride ion penetration depth was 9.8 mm was not applied. The coating agent was applied under the application conditions of the experiment No. (type of coating agent, solid content concentration of coating agent, coating amount), and further, accelerated neutralization test and chloride ion penetration as in Example 1. Tests were conducted to measure the neutralization depth and chloride ion penetration depth. The results are shown in Table 4.

  Table 4 shows that the mortar containing the aluminum sulfate surface-coated with the coating agent of the present invention suppresses neutralization and salt damage.

"Example 5"
A flat plate having a length of 30 cm, a width of 30 cm, and a thickness of 6 cm was prepared using the same mortar as in Example 1, and a commercially available surface coating material, a surface impregnation material, and a coating agent of the present invention (application conditions for Experiment No. 1-10) As in Example 1, the ease of application and the depth of neutralization were confirmed.

(Materials used)
Surface coating material: primer (acrylic resin, standard coating amount 200 g / m ² , commercially available product),
Intermediate coating material (acrylic resin, standard coating amount 200 g / m ² applied twice, commercial product), top coating material (acrylic-urethane resin, standard coating amount 200 g / m ² applied twice, commercial product)
Surface impregnating material: alkoxysilane emulsion, standard coating amount 200 g / m ² , commercial product

(result)
Since the surface coating material is one in which three types of materials are overcoated, the time required to complete the surface coating requires 8 hours because it is necessary to provide a drying time for the primer, intermediate coating material, and the like. The neutralization depth and chloride ion penetration depth after 28 days of accelerated neutralization were 0 mm.
The surface-impregnated material is only applied once to the surface with a standard coating amount of 200 g / m ² . The neutralization depth after 28 days of accelerated neutralization was 4.4 mm, and the chloride ion penetration depth was 1.3 mm.
On the other hand, in the present invention, the coating agent was only brushed once, the neutralization depth after 28 days of accelerated neutralization was 0.3 mm, and the chloride ion penetration depth was 0.2 mm. . Therefore, it can be seen that the present invention is simple to construct and can easily provide a mortar exhibiting a neutralization inhibitory effect and a chloride ion permeation inhibitory effect comparable to ordinary commercial surface coating materials.

"Example 6"
Cement 318kg / ^{m 3,} sand 829kg / ^{m 3,} gravel 997kg / ^{m 3,} water 170 kg / ^{m 3,} the concrete mix consisting of 0.5% relative to the cement water reducing agent, 2 aluminum sulfate for 100 parts of cement The mixture was mixed and kneaded, and cured in the air under an environment of a material age of 28 days, a temperature of 20 ° C., and a humidity of 80%. The test specimen size is 10 × 10 × 10 cm, the side and bottom surfaces of the test specimen are sealed with epoxy resin, and the coating conditions of the experiment No. shown in Table 5 on the top (type of coating agent, solid content concentration of coating agent) The coating amount was applied in the same manner as in Example 1 except that the coating agent was applied with a brush. The results are shown in Table 5.

(Materials used)
Sand: crushed stone from Himekawa water system, Niigata prefecture, maximum aggregate particle size 5mm
Gravel: Crushed stone from Himekawa water system, Niigata Prefecture, maximum aggregate particle size 20mm
Water reducing agent: Naphthalene sulfonate, commercial product

  From Table 5, it can be seen that the concrete containing aluminum sulfate surface-coated with the coating agent of the present invention suppresses neutralization and salt damage and is easy to apply.

"Example 7"
To 100 parts of cement, 200 parts of sand, 42 parts of water, and 0.5 part of a water reducing agent were kneaded with a 50 L plaster mixer, and the resulting mortar was pumped by 3 m with a squeeze pump. At the tip of the pressure hose, a spray nozzle is attached, and before that nozzle, the aqueous solution of aluminum sulfate is pumped with a liquid pump so that the solid content is 6 parts with respect to 100 parts of cement. Tests were conducted in the same manner as in Example 1 except that the coating agent was applied under the application conditions of Experiment No. 6 (type of coating agent, solid content concentration of coating agent, application amount). The results are shown in Table 6.

(Materials used)
Sand: Limestone sand, Niigata Aomi lime sand, Maximum particle size 1.5mm
Water reducing agent: Naphthalene sulfonate-based, commercially available aluminum sulfate aqueous solution: aqueous solution in which commercially available aluminum sulfate 18 hydrate is dissolved in water so as to have a solid content of 27%

(Blowing condition)
Plasterer mixer: Okasan Kiko Damacut mixer squeeze pump: Okasan Kiko OKG-05, mortar discharge rate 0.2m ³ / hr
Compressor: Pressure 0.7MPa, Air flow rate 0.4m ³ / min
Liquid pump: Plunger type pump (for aluminum sulfate aqueous solution)

  Table 6 shows that the mortar containing the aluminum sulfate surface-coated with the coating agent of the present invention suppresses neutralization and salt damage and is easy to apply.

"Example 8"
Cement 400 kg / ^{m 3,} sand 1055kg / ^{m 3,} gravel 713kg / ^{m 3,} kneaded concrete comprising water 200 kg / ^{m 3,} the concrete pumping machine air conveyed by (Ariba 280), one of the showering tube provided midway Thus, the aqueous aluminum sulfate solution of Example 7 was pumped with a liquid pump so that the solid content was 6 parts with respect to 100 parts of cement, merged and mixed, and sprayed onto the frame. The size of the formwork sprayed was a box form with a length of 30 cm x width of 30 cm x thickness of 15 cm. The test was performed in the same manner as in Example 6 except for the above. The results are shown in Table 7.

(Materials used)
Sand: River sand from Himekawa, Niigata Prefecture, maximum particle size 5mm
Gravel: Himekawa from Niigata gravel, maximum particle size 15mm

(Blowing condition)
Sprayer: Arriver 280 manufactured by Arriver, air consumption 10 m ³ / min, concrete discharge 5 m ³ / hr
Liquid pump: Plunger type pump (for aluminum sulfate aqueous solution)

  From Table 7, it can be seen that the concrete containing aluminum sulfate surface-coated with the coating agent of the present invention suppresses neutralization and salt damage and is easy to apply.

  The mortar or concrete of the present invention can be used for the purpose of repairing / reinforcing concrete structures in the field of civil engineering / architecture and secondary products of concrete and mortar. In particular, it is suitable for locations where neutralization and suppression of salt damage are required.

Claims (3)

100 mass of cement cemented with aluminum sulfate , the surface of which is coated with an organic-inorganic composite-type coating curing agent containing a synthetic resin aqueous dispersion, a water-soluble resin, and a swellable clay mineral, having a solid content concentration of 10 to 60 mass%. Mortar or concrete containing 0.5 to 10 parts by mass in solid content with respect to parts , in which neutralization and salt damage are suppressed . Organic - inorganic composite type coating curing agent mortar or concrete according to claim 1, wherein the swelling clay mineral is a synthetic fluorine mica. Organic - inorganic composite type coating amount of the curing agent is 50 to 500 g / ^{m 2} according to claim 1 or 2 wherein the mortar or concrete.