JP5649019B2 - Finishing method of slag mortar - Google Patents

Description

  Prevention of dry-out when using slag-based cement with sulfuric acid resistance in concrete structures that form the framework of sewerage facilities, wastewater treatment facilities, hot spring facilities, etc. The present invention relates to an improved construction method for improving the adhesiveness of a concrete frame and shortening the construction period.

  Since Portland cement produces a large amount of calcium hydroxide by hydration, it is easily eroded by inorganic acids and organic acids. That is, calcium hydroxide produced by the hydration reaction of Portland cement reacts in the presence of sulfuric acid to produce gypsum, the strength decreases, and the produced gypsum and tricalcium aluminate contained in the cement React to produce ettringite. It is thought that when this ettringite is produced, it expands and the tissue collapses.

In sewage-related facilities, hydrogen sulfide gas generated from sewage sludge is oxidized by sulfur-oxidizing bacteria, and the building concrete in the facilities is corroded and deteriorated by the generated sulfuric acid. For this reason, the surface of the concrete frame is coated with a resin having acid resistance, such as an epoxy resin having resistance to sulfuric acid, an unsaturated polyester resin, and a vinyl ester resin.
However, although these resin coatings are rare, pinholes or the like are generated, and the concrete frame may deteriorate due to sulfuric acid corrosion or the like.
Therefore, in sewage-related facilities, use of slag cement, alumina cement, etc. excellent in sulfuric acid resistance is required as mortar of the frame concrete in order to prevent damage to the facility frame.

  However, the slag cement mortar loses water when the mortar is hardened after being placed, and the surface tends to dry out. The prevention of dry-out can be improved by adding a water-holding thickener such as methylcellulose, polyvinyl alcohol, starch, etc., but the addition of these water-holding thickeners reduces sulfuric acid resistance. It is necessary to reduce the addition amount as much as possible.

  Normally, concrete and mortars that require sulfuric acid resistance are coated with acid-resistant resins such as epoxy resin, vinyl ester resin, and unsaturated polyester resin in order to prevent sulfuric acid resistance and penetration of acid-containing treated water. To do. In the case of new construction, the concrete surface is smooth, so it is possible to cover with these resins. However, in the case of renovation work, after removing the deteriorated part of the concrete, this part is backfilled and smoothed before the anticorrosion coating. Perform construction. If slag type cement mortar is used for this backfill material, it can be set as the foundation | substrate excellent in sulfuric acid resistance.

  Furthermore, synthetic resins used as typical sulfuric acid-resistant coating materials such as epoxy resins, vinyl ester resins, unsaturated polyester resins, etc. are all organic materials, and various problems occur when inorganic concrete is coated. Occurs. Typical examples are exfoliation and blistering. The cause is said to be the difference in thermal expansion / contraction characteristics between inorganic concrete and organic coating material, and the vapor pressure of water and solvent remaining in the concrete pores.

It has also been pointed out that when the concrete is in a wet state, the adhesion of the organic anticorrosion coating material is significantly reduced.
In addition, when slag or the like is used in combination with Portland cement, sulfuric acid resistance is obtained, but a sufficiently dense structure is not obtained, and permeation of sulfuric acid cannot be sufficiently prevented. That is, when the water permeability is high and treated water containing sulfuric acid passes through the coating layer (lining layer), it reaches the concrete frame and erodes the concrete. There is no point in just having sex.

At the site where sulfuric acid-resistant mortar is placed, a sulfuric acid-resistant resin is applied to the concrete surface after curing in order to increase the surface material and acid resistance of the surface as a substrate conditioner with a thickness of about 1 mm. However, it is usually applied after the mortar is sufficiently dried and cured.
For this reason, in the construction of slag cement mortar, measures against dryout and shortening of the construction period have been required.

  The present invention uses a slag-based sulfuric acid-resistant mortar for concrete structures in sewerage related facilities or waste treatment facilities, etc., without losing sulfuric acid resistance, preventing dryout, and adhesion between the resin layer and the frame concrete. It aims at providing the finishing construction method of the improved slag type mortar which enabled improvement and shortening of a construction period.

The present invention
[1] In construction of a mortar composed of a hydraulic powder containing 15% by weight or more of slag and water, after the mortar is placed, the surface of the mortar surface reaches a hardness that can be applied for up to 3 days. In addition, a slag-based mortar finishing method characterized by applying an epoxy resin-based coating material containing hydraulic powder to the mortar surface,
[2] The slag mortar according to [1], wherein the hydraulic powder in the mortar is a hydraulic composition comprising granulated blast furnace slag, Portland cement, sand and an organic or inorganic additive. Finishing method,
[3] The mortar is a slag mortar using hydraulic powder in which an aqueous polymer dispersion having a solid content of 0.1 to 25% or a re-emulsifying powder resin is mixed with Portland cement. A finishing method for slag-based mortar according to [1] or [2] above,
[4] The slag-based mortar finishing method according to any one of [1] to [3], wherein an epoxy resin that has been emulsified in water is used as the epoxy resin-based coating material.
[ 5 ] The slag mortar finish according to any one of [1] to [ 4 ], wherein the aqueous polymer dispersion is an acrylic resin or EVA resin having a concentration of 10 to 50%. Construction method and

[ 6 ] The slag-based mortar according to any one of [1] to [ 5 ], wherein the slag-based mortar is applied to a concrete structure that forms a casing of a sewerage or sewage treatment facility, a waste treatment facility, or a hot spring facility. The above problem was solved by developing a finishing method.

  When casting slag-based sulfuric acid resistant mortar, it is common practice to apply an epoxy resin coating as a base material after drying for at least 3 days at the earliest, usually after mortar placement. However, according to the present invention, after the mortar is placed, the epoxy resin-based coating material has a thickness of 0.5 on the mortar surface from the time when the mortar surface reaches a coatable hardness until 3 days. By applying at ~ 1.5mm, it is possible to prevent dryout and shorten the construction period, and to improve the adhesiveness between the resin layer and the frame concrete and shorten the construction period, and the facilities constructed by this construction method. Can be provided.

Hereinafter, embodiments of the present invention will be specifically described. However, this embodiment is specifically described in order to make the gist of the invention better understood, and does not limit the content of the invention unless otherwise specified.
The hydraulic powder used in the present invention means a hydraulic composition comprising Portland cement, aggregate (sand), various organic or inorganic additives (agents), and slag.
The slag blended in the hydraulic powder is blast furnace granulated slag, and in order to increase the sulfuric acid resistance of the hydraulic powder, an alkaline powder such as calcium is not blended. The blend ratio of the granulated blast furnace slag is at least 15 parts by weight in 100 parts by weight of the hydraulic powder.

The Portland cement used in the present invention is not particularly limited, and in terms of performance, various ordinary Portland cements can be used, such as normal strength, early strength, very early strength, moderate heat, or low heat. Therefore, it is preferable to use Portland cement having a 3CaO.SiO ₂ (hereinafter referred to as C3S) content of 60% or more. Examples of Portland cement having a C3S content of 60% or more include commercially available early-strength Portland cement and ultra-early-strength Portland cement.

As the aggregate, the material and particle size are not particularly limited, but generally silica-based or silica-alumina-based which is strong against acid is preferable, and bone containing a lot of alkaline earth oxides such as calcium carbonate and magnesium carbonate and iron. The material is not preferred because it is vulnerable to acid. For this reason, sand or quartz sand is usually used in terms of cost. In order to improve the sulfuric acid resistance, it is preferable to use aluminate clinker aggregates such as alumina cement clinker and jet cement clinker that gradually form alumina gel.
Moreover, the particle size can be used from fine to coarse depending on the application, and is preferably the same or similar to that used for ordinary cement mortar and concrete. When used as a general structural material, one having a large particle size is used.

  In the present invention, the hydraulic powder contains various organic or inorganic additives (materials) such as a water reducing agent such as a high performance water reducing agent, an AE water reducing agent or a high performance AE water reducing agent, a fluidizing agent, It is possible to use foam minerals, thickeners, rust inhibitors, antifreeze agents, shrinkage reducing agents, setting modifiers, cement expansion materials, bentonite and other clay minerals as long as they do not substantially impede the purpose of the present invention. It is.

  Furthermore, using a hydraulic powder mixed with an aqueous polymer dispersion or a re-emulsifying powder resin having a solid content of 0.1 to 25%, more preferably 3 to 10%, with respect to Portland cement, It is preferable for reasons such as improvement in adhesion to the casing and prevention of dry out of the mortar surface.

The aqueous polymer dispersion in the present invention is not particularly limited as long as it is miscible with cement, and in general, a rubber latex for cement admixture or a resin emulsion for cement admixture defined in JIS A6203-3 can be widely used.
Suitable aqueous polymer dispersions include acrylic (resin) emulsion, acrylic-styrene (resin) emulsion, EVA (ethylene-vinyl acetate resin) emulsion, SBR (styrene-butadiene rubber) latex, CR (chloroprene rubber). ) -Based latex and the like, but are not limited thereto.
By adding such an aqueous polymer dispersion, acid resistance can be enhanced, and water permeability and adhesiveness can be improved.
In particular, an aqueous acrylic emulsion, similarly an aqueous ethylene-vinyl acetate emulsion, is preferable from the viewpoint of expression of bending strength, water resistance, and adhesiveness.

The acrylic emulsion can be obtained by emulsion polymerization of a monomer composition containing one or more monomers selected from (meth) acrylic acid ester monomers. As the (meth) acrylic acid ester monomer, butyl acrylate, 2-ethylhexyl acrylate, and methyl methacrylate are preferable.
The ethylene-vinyl acetate emulsion is an emulsion of a copolymer of ethylene and vinyl acetate, and is an emulsion of 5 to 50% ethylene.

The preferable particle diameter of the aqueous polymer dispersion in the present invention is 0.05 to 10 μm, and more preferably 0.2 to 1 μm.
The solid content of the aqueous polymer dispersion is preferably 30 to 70% by weight, more preferably 45 to 60% by weight.
The viscosity of the aqueous polymer dispersion is preferably 200 mPa · s or less, and more preferably 100 mPa · s or less.
By blending an aqueous polymer dispersion, the adhesion to the housing is improved and the effect of preventing mortar dryout is obtained. However, when blended in a large amount, the sulfuric acid resistance decreases, so the total weight is 20% at most. % Is required.

The blending ratio of water in the mortar (including water in the aqueous polymer dispersion) is 35 to 65% by weight, preferably about 40 to 60% with respect to the total weight of slag and Portland cement.
When the amount of the blended water is larger than the above range, a lot of voids are easily generated in the cured mortar, and the sulfuric acid resistance is lowered. On the other hand, in the case of the above range or less, the hydration reaction of slag does not proceed sufficiently and the strength decreases.
A typical blending ratio is a ratio of the hydraulic powder 25, the aqueous polymer dispersion (solid content 45%) 1, and the water 4 in weight ratio, but is not limited thereto.

As the epoxy resin-based coating material applied to the surface after mortar placement, various commonly used epoxy resin coating materials can be used and are not particularly limited. Contains a composition mixed with a curing agent.
The epoxy resin composition used for the epoxy resin-based coating material is preferably an aqueous emulsion, and from the viewpoint of cost and performance, a bisphenol A type resin composition, for example, “shogette SA-1 main agent”. (Registered trademark: Showa Denko Building Materials Co., Ltd.) is preferable.
About 10 to 60 weight% is preferable and the density | concentration of the resin solid content of this epoxy resin composition has more preferable 30 to 50 weight%.
In addition, as the curing agent used for this, several curing agents such as amine-based, ester-based, acid anhydride-based and modified polyamine-based materials can be used. “Zet SA-1 curing agent” (registered trademark: Showa Denko Construction Materials Co., Ltd.) is preferable.

The epoxy resin-based coating material preferably contains a hydraulic powder containing Portland cement and the like from the viewpoint of adhesion to mortar, etc. It is preferably 10% by weight or more.
As this hydraulic powder, for example, “Shouzette SA-1 powder” (registered trademark: Showa Denko Construction Materials Co., Ltd.) is preferable.
Moreover, it is preferable that the content rate of the said hydraulic powder in an epoxy resin coating material is 50 to 90 weight%.

  The coating thickness of the epoxy resin coating material applied to the surface of the slag mortar is preferably about 0.1 to 5 mm, and more preferably about 0.5 to 1.5 mm.

The epoxy resin-based coating material is used before the slag-based sulfate-resistant mortar is completely cured, that is, after the mortar is placed, when the surface of the mortar has reached a coatable hardness (1 hour at the earliest, usually 3 It is necessary to apply between about 5 hours and 3 days.
The time that the mortar can be applied with the epoxy resin coating material varies depending on the temperature, the amount of water in the mortar, etc., so it is not definitive, but the mortar surface is not coated with the epoxy resin coating material. It is preferable to apply immediately after reaching a possible hardness, and it is necessary to apply within 3 days after placement.
Exceeding this period increases the possibility of mortar dryout, and cannot be expected to improve the adhesion between the resin layer and the concrete surface, and also impedes shortening the construction period.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not restrict | limited by the following Example. In addition,% in the following compounding ratio is shown by weight%.
[Example 1]
The following materials were used.
Hydraulic powder: blast furnace granulated slag 40%, Portland cement 19%, aggregate 40%, other additives 1% (hereinafter, the above composition is referred to as “sulfuric acid resistant mortar A”)
Water absorption regulator: AR primer (registered trademark: Showa Denko Construction Materials Co., Ltd.)
Water-based polymer dispersion: Petalus WP (registered trademark: Showa Denko Building Materials Co., Ltd.)
Epoxy resin coating material: Shouzetto SA-1 (registered trademark: Showa Denko Construction Materials Co., Ltd.)
The AR primer is an adhesion assistant and is a water absorption adjusting agent for the base. Petalus WP is an acrylic-styrene emulsion.

A material kneaded with sulfuric acid-resistant mortar A: petals WP: water = 25: 1: 4 was applied to a sidewalk board coated with 100 g / m ^{2 of} AR primer to a thickness of 20 mm.
And after the predetermined time passed, the showt SA-1 was constructed with a thickness of 1 mm.
The construction method was in accordance with the test method of the adhesion stability test in the Tokyo Concrete Rehabilitation Technical Manual (Processing Facility).

5 hours, 24 hours, 3 days, 5 days, and 7 days after placement of the sulfuric acid resistant mortar A, showt SA-1 was applied.
Table 1 shows the adhesion test results at a material age of 28 days. The break positions in Table 1 are: A: sidewalk board, B: material / walkway board interface, C: lower part of material, D: inside of material, E: material surface layer, F: SA-1 / material interface, G: inside of SA-1 It was.

As a result of the adhesion test, there was a large difference in strength and breakage position depending on whether or not the application of Shouzet SA-1.
In each time zone, when Showet SA-1 was applied, a part of the breaking position was from the sidewalk board.
On the other hand, in the case of no application of Shouzette SA-1, the material surface layer was broken.
The results in Table 1 are the results in the laboratory, but the material surface layer is most susceptible to external influences, so the sidewalk board is safer in all environmental conditions on the site than the material surface layer at the breaking position. It can be said.

[Example 2]
The following materials were used.
Hydraulic powder: Blast furnace slag 40%, Portland cement 19%, Aggregate 40%, Other additives 1%, Re-emulsifying powder resin: 2% (outside) (hereinafter, the above composition is referred to as “sulfuric acid resistant mortar B ”)
Water absorption regulator: AR primer (registered trademark: Showa Denko Construction Materials Co., Ltd.)
Epoxy resin coating material: Shouzetto SA-1 (registered trademark: Showa Denko Construction Materials Co., Ltd.)

A material kneaded with sulfuric acid resistant mortar B: water = 25: 4.6 was applied to a sidewalk board coated with 100 g / m ^{2 of} AR primer to a thickness of 20 mm.
And after the predetermined time passed, the showt SA-1 was constructed with a thickness of 1 mm.
The construction method was in accordance with the test method of the adhesion stability test in the Tokyo Concrete Rehabilitation Technical Manual (Processing Facility).

5 hours, 24 hours, 3 days, 5 days, and 7 days after placement of the sulfuric acid resistant mortar B, the showt SA-1 was applied.
Table 2 shows the adhesion test results at a material age of 28 days. The break positions in Table 2 are: A: sidewalk board, B: material / sidewalk board interface, C: lower part of material, D: inside of material, E: material surface layer, F: SA-1 / material interface, G: inside of SA-1 It was.

  As a result of the adhesion test, there was a large difference in strength and breakage position depending on whether or not the application of Shouzet SA-1.

Slag-based mortar containing ground granulated blast furnace slag loses water during curing and tends to cause surface dryout. In particular, this tendency is high when no water retention thickener is blended in order to increase the sulfuric acid resistance.
In addition, when placing sulfuric acid-resistant mortar, a construction method in which an epoxy resin-based coating material is applied as a base material after the mortar is dried is generally used in the present invention. In the meantime, by applying the epoxy resin coating material to a thickness of about 1 mm, it becomes possible to prevent dryout and shorten the construction period.
For this reason, the construction method according to the present invention can be used for the anticorrosion coating of Portland cementitious materials of facilities and civil engineering / building materials that come into contact with acids and the repair of defects, and further, the structural materials of those facilities and members Acid resistant materials that can be used as It can also be used as an acid-resistant repair material that can be used in strongly acidic groundwater environments.
That is, the present invention is a method for placing sulfuric acid-resistant mortar with excellent sulfuric acid resistance, such as a sewerage, wastewater treatment facilities, waste treatment facilities, incinerators or concrete structures that form the frame of a hot spring facility, The present invention provides an improved construction method capable of preventing dry-out, improving the adhesion between the resin layer and the concrete and shortening the construction period.

Claims (6)

In the construction of a mortar composed of 15% by weight or more of slag and mortar, and after mortar placement, the mortar surface reaches the applicable hardness until 3 days, A finishing method for slag mortar, characterized in that an epoxy resin coating material containing hydraulic powder is applied to the mortar surface. The finishing method for slag-based mortar according to claim 1, wherein the hydraulic powder in the mortar is a hydraulic composition comprising granulated blast furnace slag, Portland cement, sand and organic or inorganic additives.   The mortar is a slag-based mortar using hydraulic powder in which an aqueous polymer dispersion having a solid content of 0.1 to 25% or a re-emulsifying powder resin is mixed with Portland cement. A finishing method for slag mortar according to claim 1 or 2.   The slag-based mortar finishing method according to any one of claims 1 to 3, wherein the epoxy resin-based coating material is a water-based emulsion epoxy resin. The slag mortar finishing method according to any one of claims 1 to 4 , wherein the aqueous polymer dispersion is an acrylic resin or EVA resin having a concentration of 10 to 50%. The slag mortar finishing method according to any one of claims 1 to 5 , wherein the slag mortar finishing method is applied to a concrete structure that is a skeleton of a sewerage or sewage treatment facility, a waste treatment facility, or a hot spring facility.