JP2002293603A - Spraying material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement-based spraying material which has excellent acid resistance and is suitable for performing spraying work for forming a thick sprayed material and enables prevention of any cracking or peeling in the sprayed material from being caused. SOLUTION: This spraying material contains aggregate and alumina cement which has a <=25 wt.% fraction of particles having <=5 μm particle size, in a weight ratio of (alumina cement)/aggregate of 20/80 to 40/60, and also, a lithium salt which is dissolved in water of a pH of >=6 to release Li<+> ion, wherein the ratio of the content of an inorganic particle fraction having >5 μm particle size to the total content of all the inorganic particles in the spraying material is >=75 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mortar or a concrete spraying material to be sprayed on a construction surface such as a tunnel or a concrete structure.

[0002]

2. Description of the Related Art Mortar and concrete spraying materials are:
Portland cement is used as a hydraulic component, and the composition is based on the addition of a quick-setting material mainly composed of aluminate or aluminum sulfate.The physical properties, shape, angle, etc. On the other hand, compounding components have been selected in consideration of properties such as adhesion, curing time, peeling prevention after curing, and strength.

[0003]

On the other hand, in the conventional spraying material, the chemical properties of the construction object and the chemical resistance after construction have not been sufficiently considered. In particular, in areas where the object of construction is in contact with acidic substances such as sewage treatment facilities and chemical manufacturing facilities, acidic soils such as hot springs, and outdoor constructions that may be exposed to acid rain, use conventional spraying materials. The calcium hydroxide formed in the sprayed material by the hydration reaction is neutralized with such an acid to form a salt, and the salt precipitates or elutes, and the collapsed portion occurs. For this reason, alumina cement that does not form calcium hydroxide is used as a hydraulic component, and peeling and falling off after construction due to insufficient hardening speed caused by using alumina cement is reduced to ultra fine powder such as alumina ultra fine powder and silica ultra fine powder. Spraying materials that were prevented by adding materials were developed. (JP-A-11-6
[0341] However, diversification of spraying construction needs may require a thicker spraying material, and a spraying material using alumina cement as a hydraulic component is a material to which such a fine powder material is added. Even so, as the spray thickness increased, cracks were more likely to be generated after the construction, and further, they could be peeled off from the construction surface.

[0004]

The present inventors have made various studies to solve the above-mentioned problems. As a result, the cracks of the spray which are generated as the spray thickness increases are mainly caused by alumina cement. It has been found that the shrinkage is caused by the hardening shrinkage, and the shrinkage is larger in the alumina cement having more fine particles, and is larger as the fine particles of all the inorganic particles contained in the spray material are larger. From this, the ratio of fine particles in the alumina cement is limited, and the ratio of fine particles of all the inorganic particles (including alumina cement) in the spraying material is further limited, so that the shrinkage is suppressed to the extent that cracks do not occur. What you can do. In addition, by adding a lithium salt that elutes Li ⁺ to the alumina cement composition slurry immediately before spraying, the insufficient curing speed caused by the use of alumina cement can be drastically improved. The present invention has been completed because the falling off of the spray material can be sufficiently prevented, and the curing start time can be freely adjusted by the amount of the oxycarboxylic acid (salt).

That is, the present invention is a spraying material represented by the following (1) to (3). (1) Aggregate and alumina cement containing 25% by weight or less of particles having a particle size of 5 μm or less are dissolved in water having a pH of 6 or more while containing alumina cement / aggregate at a weight ratio of 20/80 to 40/60. A lithium salt that elutes Li ⁺ , wherein 75% by weight or more of all the inorganic particles contained have a particle size of 5 μm
Spraying material characterized by exceeding. (2) The spraying material according to (1), wherein the spraying material contains a polycarboxylic acid-based polymer compound having a polyalkylene glycol chain and / or a compound containing a lower alcohol alkylene oxide adduct as a main component. (3) The spray material according to the above (1) or (2), further comprising an oxycarboxylic acid (salt).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The spraying material of the present invention essentially contains alumina cement and aggregate. The alumina cement used in the present invention may be any alumina cement as long as the constituent ratio of particles having a particle size of 5 μm or less is 25% by weight or less, but is preferably a clinker containing monocalcium aluminate as a main mineral phase. Alumina cement obtained from pulverized material is recommended. If the composition ratio of the particles having a particle size of 5 μm or less exceeds 25% by weight, undesirably, the shrinkage at the time of curing becomes large and cracks may occur.

Further, as the aggregate used in the present invention, a known fine aggregate is used. Any type of fine aggregate may be used, but preferably those known as acid-resistant aggregates, such as alumina aggregate, mullite aggregate, chamotte aggregate, silicalite aggregate, silicon carbide aggregate, Furthermore, an alumina cement clinker aggregate and the like can be mentioned.

The mixing ratio of the alumina cement and the aggregate is alumina cement / aggregate = 20 / 80-40 by weight ratio.
/ 60. High acid resistance and strength and good workability can be imparted by setting the mixing ratio. In addition, in the present invention, 75% by weight or more of all the inorganic particles (including alumina cement and aggregate) contained in the composition exceed 5 μm in particle diameter. By regulating the particle size, shrinkage during curing can be further reduced.

It is preferable that a compound mainly composed of a polycarboxylic acid polymer having a polyalkylene glycol chain and / or a lower alcohol alkylene oxide adduct is blended with the compound. By compounding this compound, uniform dispersibility and high fluidity suitable for spraying can be imparted without increasing the amount of water, and further drying shrinkage after curing can be reduced. In addition, the present inventors have also confirmed that a polycarboxylic acid-based polymer compound having a polyalkylene glycol chain or a compound containing a lower alcohol alkylene oxide adduct as a main component has an effect of reducing the amount of curing shrinkage. . The compounding amount of the compound is based on 100 parts by weight of the alumina cement.
The amount is 0.01 to 1.0 part by weight for a polycarboxylic acid polymer compound having a polyalkylene glycol chain, and 0.1 to 8.0 parts by weight for a compound mainly containing a lower alcohol alkylene oxide adduct. In any case, if the amount is less than the lower limit, the dispersibility and fluidity are hardly exhibited, and if the amount exceeds the upper limit, the curing is delayed, which is not preferable. When both are used in combination, they can be used in the respective compounding amount ranges, and the compounding ratio between the two is not limited.

Poly having an alkylene glycol chain
The carboxylic acid-based polymer compound may be any one, for example,
Ba (D¹) Having a polyalkylene glycol chain
(T) acrylic acid copolymer, (D^Two) Polyalkylene
Maleic acid-based copolymer having a recall chain (polyvalent metal salt
Etc.) are particularly recommended. Also, two or more of these
A mixture of copolymers may be used. Where (D¹As)
Is a -COOM group (M is a hydrogen atom, an alkali metal,
Potassium earth metal, ammonium or organic amine
Having a polyalkylene glycol chain)
Acrylic acid-based copolymers can be mentioned as preferred examples.
And (D^Two) Is polyalkylene glycol
Alkenyl ether-maleic anhydride copolymer (polyvalent gold
And the like. Any poly
The alkylene glycol chain also has -O (CH _TwoCH (R)
O)_bThe one represented by-is desirable. (R is a hydrogen atom or
Represents a methyl group, b represents 2 to 200, preferably 5 to 1
09. ) (D¹) (Meth) acrylic acid copolymer
The body has a number average molecular weight of 2000 to 50,000 (GPC method)
Method, polyethylene glycol equivalent) is preferable,
3500-30000 is more preferable. Also, (D^Two)
Maleic anhydride copolymer is methyl polyethylene glycol.
Recohol vinyl ether-maleic anhydride copolymer,
Polyethylene glycol allyl ether-maleic anhydride
Copolymer, methyl polyethylene glycol allylate
-Maleic anhydride copolymer, methyl methacrylate poly
Examples include ethylene glycol-maleic acid copolymer
be able to. Number average of (meth) acrylic acid copolymer
The molecular weight is 3000-200000, especially 3000-80
000 is preferred.

The compound containing a lower alcohol alkylene oxide adduct as a main component is not particularly limited as long as it is generally used as an admixture for reducing drying shrinkage of concrete or mortar.

This composition is dissolved in water having a pH of 6 or more and dissolved in water.
Essentially contains a lithium salt that elutes i ⁺ . The reason why the lithium salt to be used is limited to one that dissolves in water having a pH of 6 or more is that the pH of a slurry obtained by adding water to alumina cement is usually p
The reason for this is that the content is less than H6, and the effect of accelerating the curing by Li ⁺ becomes remarkable in a weakly acidic to alkaline region. The lithium salt used in the present invention is to supply lithium ions in an amount corresponding to the amount of alumina cement into the slurry promptly without any excess or shortage. It is preferable to use a lithium salt having a solubility at 20 ° C. of 10 or more, and it is desirable to use it in the form of an aqueous solution. In the case of a lithium salt having a solubility of less than 10, a large amount of diluting water is required when forming an aqueous solution, and the effect of promoting the effect is reduced due to an aqueous solution having a low lithium ion concentration. Further, lithium salts which exhibit weak acidity to alkalinity in an aqueous solution are preferable because they can exert a strong curing promoting action, and those having a pH of 10 or more are particularly preferable. Suitable lithium salts include lithium hydroxide, lithium nitrate, lithium nitrite and the like. The amount of the lithium salt is 0.05 to 5 parts by weight based on 100 parts by weight of the alumina cement. If the compounding amount is less than 0.05 part by weight, the amount of Li ⁺ required for promoting the hardening of the alumina cement cannot be secured.
If the amount is more than 10 parts by weight, the effect of promoting the curing is not further improved, which is not preferable.

The spraying material may contain oxycarboxylic acids (salts). Oxycarboxylic acids (salts) are effective in imparting the pot life of spraying from the time of mixing water to the time of spraying. To increase the pot life, increase the compounding amount and shorten the pot life. To reduce the amount of compounding, the pot life can be adjusted almost freely. The content of the oxycarboxylic acid (salt) in the present admixture which is effective in imparting the pot life corresponds to 0.01 to 3 parts by weight based on 100 parts by weight of the alumina cement to which the present admixture is added. The amount is preferred. If the amount is less than 0.01 part by weight, the pot life is hardly imparted, which is not preferable. On the other hand, if the amount exceeds 3 parts by weight, the curing retardation becomes too large, and the strength development may be impaired. The oxycarboxylic acid (salt) used is not particularly limited,
Desirably, a weakly acidic to neutral one is preferred, and tartaric acid, citric acid, gluconic acid and the like can be mentioned as preferable examples.

Further, in the present invention, a spraying material containing components other than the above may be used as long as the components do not affect the curing characteristics and the acid resistance. As an example, a defoamer and a thickener for mortar can be mentioned.

The spraying material of the present invention is prepared by adding water to a compound comprising the above components except for the lithium salt to form a slurry, and then adding the aqueous solution of the lithium salt to the slurry. The amount of water added during the preparation of the slurry is 10 to 30 parts by weight based on 100 parts by weight of the solid content of the blend. If the amount of water exceeds 30 parts by weight, it is difficult to obtain a cured product having high strength and water tightness, and it is not preferable. It is not preferable because it occurs. Further, in order to make the lithium salt into an aqueous solution, the lithium salt is added to water having a pH of 6 or more and the mixture is stirred so that the concentration becomes approximately 9 to 50% by weight. It is desirable to mix the lithium salt aqueous solution in the slurry as soon as possible before the spraying. For example, the slurry is supplied to the stirring slurry by a Y-tube. The method of the spraying operation itself is not particularly limited. For example, the operation by a conventional spraying machine can be sufficiently performed.

[0016]

EXAMPLES The present invention will be specifically described with reference to examples.
For reference, those deviating from the scope of the present invention are also described as comparative examples.

[Raw Materials] A raw material selected from the following [1] to [4] was used. [1] Alumina cement The main chemical components are Al ₂ O ₃ : 50.7%, CaO: 3
Alumina cement clinker of 6.5%, Fe ₂ O ₃ : 6.0%, SiO ₂ : 5.0% was pulverized by a ball mill and a vibration mill, and the particle size was adjusted by a wind sieve to obtain particles having a particle size of 5 μm or less. With a content of 10% by weight (abbreviated as A1), 2
Select from either 0% by weight (abbreviated as A2) or 30% by weight (abbreviated as A3).

[2] Aggregate Silica (abbreviated as S1G) having an average particle size of 1.5 mm (the content of particles having a particle size of 5 μm or less is 0.5% by weight), an average particle size of 8 μm
m (the content of particles having a particle size of 5 μm or less is 91.4% by weight) or fine silica powder (abbreviated as S2) having an average particle size of 0.7 μm (the content of particles having a particle size of 5 μm or less is 99.8% by weight). Selected from any of silica fumes (abbreviated as S3).

[3] Admixture A commercially available powdery dispersant (trade name: “Merment F1”) containing melamine sulfonic acid formaldehyde polycondensate as a main component.
0, manufactured by SKW East Asia, abbreviated as ME), and a commercially available powdered dispersant having a polycarboxylic acid-based polymer compound having a polyethylene glycol chain as a main component (trade name “Coreflow NF-100” manufactured by Taiheiyo Cement Corporation) (Hereinafter abbreviated as CF), a commercially available shrinkage reducing agent containing a lower alcohol alkylene oxide adduct as a main component (trade name "Tetraguard AS21" manufactured by Taiheiyo Cement Corporation, abbreviated as TG), and an acrylic re-emulsifying powder resin. A commercially available thickener as a component (trade name “DRYCRYL DP-2904” manufactured by Rohm and Haas Company, abbreviated as “DP”), a commercially available methylcellulose thickener (trade name “hi-Metroze” manufactured by Shin-Etsu Chemical Co., Ltd.) , MC), tartaric acid (commercially available reagent,
TA or a defoamer (“SN-Deformer 14HP” manufactured by San Nopco, abbreviated as DF).

[4] Aqueous solution of lithium salt 15% aqueous solution of lithium hydroxide (abbreviated as L1) or 30% aqueous solution of lithium nitrate (abbreviated as L2)

[Ingredients of raw materials] The weights shown in Table 1 are based on 100 parts by weight (all in terms of solid content) of the blends obtained by mixing and adjusting the raw materials of [1] to [3] at the ratios shown in Table 1. Of water, and the mixture was mixed and kneaded for about 3 minutes with a high-speed mortar mixer to prepare a slurry. Table 1 also shows the content (% by weight) of particles having a particle size of 5 μm or less for all the inorganic particles excluding the lithium salt in the formulation.

[0022]

[Table 1]

[Properties of kneaded material]
The fluidity (mortar flow value) was measured by a method according to SR5201 from the time immediately after the completion of kneading to the time when 90 minutes passed. The results are shown in Table 2. Further, in order to confirm the pumpability of the slurry, a pumping tube having an inner diameter of 40 mm and a length of 30 mm was used to perform pumping at a spraying speed of 2 m ³ / hour for 30 minutes. However, in any of the embodiments according to the present invention, the pumping tube was used. No clogging phenomenon was observed.

[0024]

[Table 2]

[Curing Properties] Next, from the preparation of the slurry, 3
After 0 minutes, the slurry has a solid content of 10%.
0 parts by weight of the lithium salt aqueous solution of [4] described in Table 1 was added in parts by weight and kneaded for 10 seconds using a hand mixer to prepare a kneaded product. The initial quick-setting property of the kneaded material was measured as a proctor penetration resistance value from 30 seconds to 5 minutes after kneading according to a method according to SATM-C403T (concrete coagulation test method using a proctor penetration resistance needle). did. Furthermore, the kneaded material is φ50 × 100
mm, and the depth from the upper end surface of the mold to the upper surface of the kneaded material filling: HM was measured. Then, after 1 minute of filling, pour silicone oil into the top surface of the kneaded material so as to have a thickness of about 5 mm, immediately measure the depth: H0 from the upper end surface of the mold to the top surface of silicon oil, and 4 hours from the time of pouring the silicone oil. Then, 24 hours and 48 hours later, the depth: HX from the upper end surface of the mold to the upper surface of the silicone oil was measured, and the curing shrinkage during curing was calculated from the following equation. Curing shrinkage (%) = 100 × (HO-HX) / (100
-HM) Table 2 shows the above results.

[Properties of Cured Body] The long-term strength development after curing of the kneaded material was evaluated by using a test piece (40) prepared by filling the kneaded material with a mold.
(× 40 × 160 mm) was measured by a method according to JIS R 5201 as the compressive strength at the age of 28 days. Also,
The kneaded product was sprayed on a 400 × 400 × 40 mm concrete plate using a spraying machine using a Y-tube so as to have a thickness of about 5 mm and about 30 mm, and a spraying pressure of 2 kg / cm ² .
Spraying was performed at a spray amount of 3 m ³ / hour. The concrete plate sprayed to each thickness was placed in a thermo-hygrostat at a humidity of 40% and a temperature of 40 ° C., and after 24 hours, the sprayed material was visually inspected for cracks. Those with poor adhesion and those that could hardly be sprayed were excluded from observation. Further, a cylindrical molded product of φ75 × 150 mm was prepared from the kneaded product, and this was heated at a temperature of 20 days until the age of 28 days.
Cured in ion-exchanged water at ± 1 ° C., and measured the permeation-diffusion resistance and mass reduction rate of the cured product after curing in a sulfuric acid aqueous solution (pH 0.4 ± 0) for 30 days using a method in accordance with JSTMC 7401, Building Materials Testing Center Standard. 1. Measured by immersion in 1). The value of permeation diffusion resistance was represented by the depth of penetration of sulfuric acid into the cured product after immersion in sulfuric acid (mm). Table 3 shows the above results.
To

[0027]

[Table 3]

[0028]

The spraying material of the present invention has a remarkably enhanced acid resistance, so that it can be sprayed even on an object which has been previously unsuitable for the object to be applied. The spray can be applied, does not peel or collapse, and exhibits high strength over the initial to medium to long term.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // (C04B 28/06 C04B 22:06 Z 22:06 22:08 Z 22:08 24:26 H 24 : 26 22:02 22:02 22:06 A 22:06) F term (reference) 2D055 DB00 KA08 LA06 4G012 MA00 MB00 PA04 PB03 PB05 PB15 PB17 PB31 PB32 PB35 PB40

Claims (3)

[Claims] An alumina cement containing 25% by weight or less of an aggregate and particles having a particle size of 5 μm or less in a weight ratio of alumina cement / aggregate = 20/80 to 40/60 and water in a pH of 6 or more. A spraying material comprising a lithium salt that dissolves and elutes Li ⁺ , wherein 75% by weight or more of all the inorganic particles contained have a particle size of more than 5 μm. 2. The spraying material according to claim 1, wherein the spraying material contains a polycarboxylic acid-based polymer compound having a polyalkylene glycol chain and / or a compound containing a lower alcohol alkylene oxide adduct as a main component. 3. The spraying material according to claim 1, further comprising an oxycarboxylic acid (salt).