KR100447834B1 - Accelerating agent, spraying material and spraying method employing it - Google Patents

Abstract

Accelerators containing calcium aluminate, aluminum sulfate and alkali metal sulphate.

Description

Accelerator, spray and spray method using the same {ACCELERATING AGENT, SPRAYING MATERIAL AND SPRAYING METHOD EMPLOYING IT}

FIELD OF THE INVENTION The present invention relates to sprays to be sprayed on exposed surfaces on accelerators, roads or railways, or in tunnels such as conduits, and spraying methods using the same. For the purposes of the present invention, cement concrete is used in general terms including paste, mortar and concrete.

Until now, in order to prevent settlement of the exposed surface by excavation of tunnels, it has been common to use a method of spraying fast curing concrete mixed with accelerators in concrete (JP-B-60-4149).

The method is to mix the cement, aggregate and water in the measurement and mixing plant installed in the excavation site to prepare the sprayed concrete, transfer it to the stirring car, and pressurized by the concrete pump and pressurized separately of the accelerator and passageway It is a method of obtaining concrete for rapid curing spraying by mixing in a converging pipe mounted at an intermediate position, and then spraying it on the surface until it reaches a predetermined level of thickness.

As accelerators used herein, calcium aluminate and / or alkali metal aluminates, or mixtures thereof with alkali metal carbonates are known (JP-A-64-15351, JP-B-56-27457, JP- A-61-26538 and JP-A-63-210050).

Recently, it has been found that alkali-flocculating reaction-inhibiting accelerators, including aluminum sulfate, are useful as permanent structures that can improve long term strength or can be used over long periods of time. As such, an alkali-agglomerate reaction-inhibiting accelerator comprising a mixture of aluminum sulfate, calcium aluminate and hydrated aluminum sulfate with crystal water has been proposed (JP-A-8-48553).

However, when using a conventional accelerator, there was a problem that the bounce rate during spraying was large, or the long term strength could hardly be obtained.

In addition, when a mixture of calcium aluminate and hydrated aluminum sulfate is used, the initial strength is low, especially when the temperature is low, the initial strength tends to be very low, and there is a problem of being sensitive to the influence of water / cement ratio.

The present inventors have conducted various studies on the problem, and found that the problem can be solved by using a specific spray material. The present invention has been accomplished based on this finding.

That is, the present invention provides an accelerator comprising calcium aluminate, aluminum sulfate, and alkali metal sulfate, wherein the alkali metal sulfate is 10 to 30 parts by weight per 100 parts by weight of accelerator, and CaO / Al ₂ O ₃ (molar ratio) is 1.5 to 3.0 and the promoter further comprises an aromatic sulfonic acid and / or an aromatic sulfonate-formaldehyde condensate, is powdered, further comprises water, and the pH is Less than 7, and in the accelerator, the vitrification ratio of calcium aluminate is at least 40%.

The present invention also provides a spray material comprising cement concrete containing cement, wherein the accelerator is mixed with the cement concrete, wherein the cement concrete further comprises polyalkylene oxide, further Fiber material was included.

In another aspect, the present invention provides a spraying method comprising the pressurized injection of the accelerator with compressed air and mixing with the cement concrete.

The present invention will now be described in detail.

Accelerators used in the present invention included calcium aluminate, aluminum sulfate and alkali metal sulfates.

Calcium aluminate used in the present invention includes CaO and Al ₂ O ₃ as main components, and as a general term for a material having a hydration activity, a material containing calcia and a material containing alumina are mixed, It can then be obtained by heating, such as by calcination in a kiln or by melting in an electric furnace, in which a part of CaO and / or Al ₂ O ₃ is for example alkali metal oxide, alkaline earth metal oxide, silicon oxide, oxidation A compound substituted with titanium, iron oxide, an alkali metal halide, an alkaline earth metal halide, an alkali metal sulfate or an alkaline earth metal sulfate, or a solid solubilized compound in a small amount in a substance containing CaO and Al ₂ O ₃ as main components It is a substance having a thing. In inorganic morphological aspects, the compound may be crystalline or amorphous.

Of these, calcium aluminate is preferable in view of reactivity. More preferred is a mixture comprising amorphous calcium aluminate corresponding to composition 12CaO.7Al ₂ O ₃ (hereinafter referred to as C ₁₂ A ₇ ), obtained by quenching the heat treated product.

The vitrification ratio of calcium aluminate is preferably at least 40%, more preferably at least 60%, even more preferably 80% in terms of accelerating the initial cure, improving the initial strength and reducing the bounce rate. Most preferably, it is 100%. If the ratio is less than 40%, the curing or development of strength tends to be impaired, and the bounce rate tends to increase.

Here, the vitrification ratio is obtained by a method in which the calcium aluminate of the present invention is heated at 1,000 ° C. for 2 hours and then slowly cooled at a cooling rate of 5 ° C./min, whereby the main peak of the crystalline inorganic material The area S _{0 of} is obtained by a powder X-ray refraction method, and the vitrification ratio χ is obtained from the main peak area S of the crystal of calcium aluminate in the sample of the present invention and S _{0 according} to the following formula (1). 1] χ (%) = 100 x (1-S / S ₀ )

CaO / Al ₂ O ₃ (molar ratio) of calcium aluminate is generally from 1.5 to 3.0, preferably from 1.7 to 2.5, in terms of accelerating the initial cure, improving the expression of the initial strength, and reducing the bounce rate. . When the said ratio is less than 1.5, there exists a tendency for the expression of curability or initial strength to be impaired, and a bounce rate will become large. On the other hand, when the ratio exceeds 3.0, there is a tendency that the expression of the curable or initial strength is impaired, the bounce rate tends to be large, which is not economically desirable.

The particle size of the calcium aluminate is preferably at least 4,000 cm ² / g, more preferably at least 5,000 cm ² / g, as a Blaine value, in terms of the manifestation of accelerated curing or initial strength. If the particle size is less than 4,000 cm ² / g, there is a tendency for the manifestation of accelerated curing or initial strength to be inferior.

Aluminum sulfate used in the present invention is a component that accelerates the initial curing and reduces the bounce rate; In the hydration reaction process of cement, aluminum ions reacting with calcium ions from cement or calcium aluminate are supplied to form calcium aluminate hydrate, and further react with sulfate ions to form calcium sulfoaluminate hydrate in the initial stage. In the manner of forming contributes to improved expression of initial intensity.

Aluminum sulfate may be used in the form of anhydrides or hydrates, and anhydrides and hydrates may be used in combination. Of these, hydrates are preferred because they are more effective in accelerating initial cure, reducing bounce rates, and improving the expression of initial strength.

The amount of aluminum sulfate, when calculated as anhydride, is preferably 5 to 100 parts by weight, more preferably 10 to 45 parts by weight, most preferably 10 to 40 parts by weight per 100 parts by weight of calcium aluminate. When the amount is less than 5 parts by weight, the bounce rate tends to be large, the initial curing tends to be inferior, and when the amount exceeds 100 parts by weight, the expression of long-term strength tends to be impaired. .

Alkali metal sulfates used in the present invention are components that improve the expression of initial strength.

Examples of the alkali metal sulfates include sodium sulfate, potassium sulfate, sodium hydrogen sulfate, sodium sulfite, potassium alum, chromium alum and iron alum. Of these, at least one member selected from the group consisting of sodium sulfate, potassium sulfate and potassium alum is preferred, since the expression of curability or initial strength is excellent, sodium sulfate and / or potassium sulfate are more preferred, and sodium sulfate is most preferred. desirable.

Alkali metal sulfates can be used in the form of anhydrides or hydrates, and anhydrides and hydrates can be used in combination. Among them, anhydrides are preferable in view of stability.

The amount of alkali metal sulfate is preferably 10 to 30 parts by weight, more preferably 15 to 20 parts by weight per 100 parts by weight of accelerator including calcium aluminate, aluminum sulfate and alkali metal sulfate. When the amount is less than 10 parts by weight, the bounce rate tends to be large, the development of initial strength tends to be impaired, and when the accelerator is a slurry, the pressure injection property of the hardened cement concrete tends to be inferior. ; When the amount exceeds 30 parts by weight, there is a tendency that the expression of curable or long-term strength is impaired.

Accelerators may be used in combination with gypsum or cure accelerators for the purpose of improving the initial cure or the development of strength.

In the present invention, accelerators including calcium aluminate, aluminum sulfate and alkali metal sulphate are used in terms of reducing the bounce rate and improving the expression of strength. In terms of reducing the bounce rate, or dust, water (hereinafter referred to as slurry water) may be further mixed to obtain an accelerator slurry.

In the case of promoter slurries, their pH is usually less than 7, preferably from 3 to less than 7, in order to accelerate initial cure, to improve the development of initial strength, or to pressurize the promoter slurry, or to reduce the bounce rate. , More preferably, it is 4-6. When the said pH is less than 3, there exists a tendency for the hardening | curing or initial strength expression to be impaired, and a bounce rate tends to become large, and when said pH is 7 or more, pressurization property tends to be inferior and long-term strength The expression tends to be impaired, and the bounce rate tends to be large. Here, the pH of the promoter slurry for the purposes of the present invention is the pH of the diluted product in which the promoter slurry is diluted 10 times further with water.

The amount of slurry water is preferably 30 to 600 parts by weight, more preferably 50 to 80 parts by weight per 100 parts by weight of accelerator. When the amount is less than 30 parts by weight, the amount of dust cannot be reduced, and when the amount exceeds 600 parts by weight, the expression of strength tends to be inferior.

In order to improve the properties of cement concrete, curing retarders, thickeners and ultrafine powders can be blended into the slurry water. In addition, aluminum sulfate or an alkali metal sulfate can be dissolved and used in slurry water.

On the other hand, when a powder accelerator is used as the accelerator, there is an advantage in that the operation is easy since no step of wetting or slurrying the accelerator is necessary.

The amount of accelerator is preferably 2 to 25 parts by weight, more preferably 5 to 20 parts by weight and most preferably 7 to 15 parts by weight, per 100 parts by weight of cement, when calculated in terms of solids content. If the amount is less than 2 parts by weight, it tends to be difficult to accelerate the initial curing, and if the amount exceeds 25 parts by weight, the expression of long-term strength tends to be impaired.

The cements used in the present invention include, for example, many Portland cements (such as normal high initial strength Portland cement, ultra-high initial strength Portland cement and mildly heated Portland, for example) Cement), and blast slag or fly ash can be various mixed cements mixed with Portland cement, which can be micronized for use. Of these, normal Portland cement and / or high initial strength Portland cement are preferred because the press injection of cement concrete can thereby be excellent.

In the present invention, it is also preferred to use polyalkylene oxides in the cement concrete side to reduce the bounce rate or the amount of dust.

The polyalkylene oxides (hereinafter referred to as PAOs) used in the present invention impart viscosity to the cement concrete to prevent the cement concrete from subsidence from the spray surface immediately after spraying, or to reduce the bounce rate or the amount of dust. will be. Examples of polyalkylene oxides include polyethylene oxide, polypropylene oxide or polybutylene oxide. Of these, polyethylene oxide is preferred because it is more effective in imparting viscosity to cement concrete and reducing the amount of dust bounce or spray during spraying.

The molecular weight of PAO is preferably 1,000,000 to 5,000,000. When the molecular weight is less than 1,000,000, the viscosity of the cement concrete becomes small, and there is a tendency that the cement concrete cannot be prevented from sinking from the spray surface immediately after spraying. When the molecular weight exceeds 5,000,000, the development of strength tends to be impaired, and when the accelerator is a slurry, the pressure injection property of the hardened cement concrete produced by mixing the cement concrete and the accelerator tends to be inferior.

The amount of PAO is preferably 0.001 to 0.2 parts by weight, more preferably 0.005 to 0.1 parts by weight per 100 parts by weight of cement. When the amount is less than 0.001 parts by weight, the viscosity of the fastening cement concrete becomes small, so that the amount of dust tends to be large and the bounce rate tends to be large. When the amount exceeds 0.2 parts by weight, the viscosity or reversion ratio of the cement concrete tends to be large, the amount of dust tends to be large, and when the accelerator is a slurry, the pressure-injection property of the hardened cement concrete is inferior. There is a tendency to lose.

In the present invention, it is also preferred to use aromatic sulfonic acid and / or aromatic sulfonate-formaldehyde condensates on the promoter side for the purpose of reducing the bounce rate or the amount of dust.

The aromatic sulfonic acids and / or aromatic sulfonate-formaldehyde condensates (hereinafter commonly referred to as aromatic sulfonates) used in the present invention improve the flowability of the cement concrete or the dispersibility of the accelerator, and the adhesion of the property hardened cement concrete upon spraying. To improve the properties, reduce the bounce rate or the amount of dust, which can be used in the form of liquids or powders. In addition, when they react with the polyalkylene oxide in the cement concrete to increase the viscosity, the adhesion of the fast curing cement concrete upon spraying is improved, and the effect of reducing the bounce rate or the amount of dust is increased.

Aromatic sulfonates include, for example, aromatic sulfonic acids such as naphthalene sulfonic acid, alkylnaphthalene sulfonate, bisphenol A sulfonic acid, phenol sulfonic acid, trisphenol sulfonic acid, 4-phenoxybenzene-4'-sulfonic acid, methyldiphenylethersulfonic acid or anthracene sulfonic acid and It may be a formaldehyde condensate of such aromatic sulfonic acid. The aromatic ring may also have an alkyl group. Among them, aromatic sulfonate-formaldehyde condensates are preferred, which improves the flowability or dispersibility of accelerators in cement concrete, improves the adhesion of hardened cement concrete in spraying, and improves the bounce rate or amount of dust. More effective in reducing. At least one selected from the group consisting of naphthalenesulfonate-formaldehyde condensates, alkylnaphthalenesulfonate-formaldehyde condensates and bisphenol A sulfonate-formaldehyde condensates is more preferred, and β -naphthalenesulfonate-formaldehyde Most preferably condensates (hereinafter referred to as β- NS).

The amount of the aromatic sulfonate is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3 parts by weight per 100 parts by weight of the accelerator containing calcium aluminate, aluminum sulfate and alkali metal sulfate. If it is less than 0.05 part by weight, the effect of improving the flowability of the cement concrete or the dispersibility of the accelerator, the effect of improving the adhesiveness of the hardened cement concrete when spraying, and the effect of reducing the reflow rate or the amount of dust tends to be worsened. If it exceeds 5 parts by weight, the bounce rate is increased, the amount of dust is increased, and the strength is worsened.

In addition, in the present invention, it is preferable to use a fiber material for fast curing cement concrete in view of improving the bending stiffness, impact resistance and toughness of the fast curing cement concrete. The fiber material used in the present invention may be inorganic or organic. As inorganic fiber materials, for example, glass fibers, rock wool, asbestos, ceramic fibers or metal fibers may be mentioned, and as organic fiber materials, for example, vinylon fibers, polyethylene fibers, polypropylene fibers, polyacrylic fibers , Cellulose fibers, polyvinyl alcohol fibers, polyamide fibers, pulp, hemp, wood fibers or wood chips. Carbon fibers can also be used. Of these, metal fibers and / or vinylon fibers are preferred from the viewpoint of economic efficiency.

The length of the fiber material is preferably 50 mm or less, more preferably 30 mm or less, from the viewpoint of pressurization injection or miscibility. If this exceeds 50 mm, the press injection pipe is likely to be clogged during press injection.

The amount of the fiber material is preferably 0.1 to 1.5 parts by volume, more preferably 0.3 to 1.2 parts by volume with respect to 100 parts by volume of cement concrete including the fiber material. If it is less than 0.1 part by volume, the bending stiffness, impact resistance and toughness cannot be improved, and if it is more than 1.5 volume ratio, the pressurization property of the property hardened cement concrete tends to be worse, and the impact resistance or the expression of strength is poor. Tend to.

In the present invention, an AE agent or a blowing agent is added to reduce the amount of dust by introducing air bubbles.

The amount of water in the cement concrete is preferably 35 to 65 parts by weight, more preferably 40 to 55 parts by weight based on 100 parts by weight of cement. If it is less than 35 parts by weight, the cement concrete cannot be sufficiently mixed, and if it is more than 65 parts by weight, the expression of strength tends to be poor. As used herein, "water" does not include slurry water.

The aggregate used in the present invention is not particularly limited as long as it is sprayable. However, it is desirable to have high aggregate strength. As fine aggregate, for example, river sand, gang sand, lime sand or silica sand can be used, and as coarse aggregate, for example, river gravel, gang gravel or lime gravel can be used.

According to the spraying method used in the present invention, in view of the required physical properties, economical efficiency and operating efficiency, the spraying may be performed in the form of fast curing cement concrete.

As a spraying method when the accelerator is not slurried, the cement concrete and the powdered accelerator are separately injected under pressure to combine and mix the cement concrete and the powdered accelerator to form a fast curing cement concrete, which is then sprayed.

As a spraying method when an accelerator slurry is used, cement concrete and an accelerator are separately injected, and water is added to the accelerator to form an accelerator slurry immediately before combining and mixing the cement concrete and the accelerator to form an accelerator slurry, and such an accelerator slurry Were combined and mixed with cement concrete to produce a fast curing cement which was then sprayed. Herein, wet spray method or dry spray method can be used. Among these, the wet spray method is preferable because the amount of dust is small.

As a wet spray method when accelerator slurry is used, cement, aggregate and water are mixed and kneaded, transported under atmospheric pressure, water is added to the promoter immediately before the accelerator is added to obtain an accelerator slurry, and then Y branched tube By addition from one of them, mention may be made of the spraying method which is then sprayed.

As a dry spraying method in which an accelerator slurry is used, mention may be made, for example, of a cement and aggregate mixed and conveyed under atmospheric pressure, to which an accelerator slurry obtained in the same manner as in the wet spraying method is added, followed by spraying.

That is, the accelerator is slurried and mixed with the cement concrete, whereby the amount of dust or the bounce rate can be reduced, and the working environment can be improved.

The method of slurrying the accelerator is not particularly limited. However, for example, it is preferable to use a method of making a slurry by adding water under high pressure from a hole made in several zones around the branch of one of the Y branch tubes for transporting the promoter under atmospheric pressure. This high pressure water has the effect of injecting the accelerator slurry into the cement concrete to improve the performance of the mixing.

The reactivity with cement concrete can thus be increased, the amount of dust or bounce rate is reduced, the development of hardenability or strength is improved, and the quality of cement concrete for rapid curing hardening is also stabilized.

In the spraying method of the present invention, conventional spraying equipment or the like can be used. The spray equipment is not particularly limited as long as the spraying can be performed properly. For example, for pressurized injection of cement concrete, for example, the brand name "Ariber 280" manufactured by Ariber may be used, and for pressurization of accelerators, "Natmcrete" of Chiyoda Manufactory, which is an accelerator pressurized injection device, may be used. In order to add water to the promoter to make the promoter slurry, a conventional water pump can be used, and a method of introducing compressed air during the addition of water can also be used. The pressure in the pressurized injection of cement concrete is preferably greater than 0.2 to 0.6 MPa. Further, the pressure of the compressed air for injecting the accelerator under pressure is preferably 0.01 to 0.3 MPa greater than the pressurized injection pressure of the cement concrete.

In addition, the pressurized injection speed of fast curing cement concrete is preferably 4 to 20 m ³ / hr. Further, in order to promote the mixing of the accelerator and the cement concrete, the shape of the tube or the inner wall of the tube at the point where the accelerator and the cement concrete are gathered can be made to have a spiral structure or a structure for turbulent flow.

The invention is now described in detail with reference to test examples. However, it should be understood that the present invention is in no way limited by the particular test examples.

Test Example 1

The spray concrete is prepared so that the unit amount of each material is 500 kg / m ³ of cement, 200 kg / m ^{3 of} water, 1,173 kg / m ^{3 of} fine aggregate, and 510 kg / m ^{3 of} coarse aggregate, and PAO is added to 100 parts of cement. It was added in an amount of 0.02 parts by weight, and the fiber material was added in an amount of 1.0 parts by volume with respect to 100 parts by volume of the sprayed concrete containing the fiber material. The sprayed concrete was pressurized with a concrete pressurizer "Ariber 280" at an injection pressure of 4 m ³ / hr under an injection pressure of 0.4 MPa.

On the other hand, 100 parts by weight of calcium aluminate, 18 parts by weight of alkali metal sulfate per 100 parts by weight of the accelerator containing aluminum aluminate ①, aluminum sulfate and alkali metal sulfate, And 2 parts by weight of aromatic sulfonate α per 100 parts by weight of accelerator. The powdery accelerator was pressurized with compressed air so as to be 10 parts by weight with respect to 100 parts by weight of cement.

The accelerator was pressurized under an injection pressure of 0.5 MPa and mixed with the sprayed concrete to obtain a hardening sprayed concrete. This fast curing spray concrete was evaluated and the results are shown in Table 1.

Used materials

Cement: ordinary Portland cement, commercially available products, Blaine value: 3,200 cm ² / g, specific gravity: 3.16

Fine aggregate: River sand produced in Himekawa, Niigata Prefecture, Japan, Surface moisture content: 4.0%, specific gravity: 2.62

Coarse aggregate: River gravel produced in Himekawa, Niigata Prefecture, Japan, surface dryness, specific gravity: 2.64, maximum size: 10 mm

PAO: Polyethylene oxide, Molecular weight: 200,000, Commercial product

Fiber material: steel fiber, length: 30 mm, specific gravity: 7.8, commercially available products

Calcium aluminate ①: mainly for the composition containing C ₁₂ A ₇ , amorphous, blind value: 6,000 cm ² / g, calcia material and alumina material are mixed in a predetermined ratio, After melting, it was quenched to have a vitrification ratio of 100% and then ground. CaO / Al ₂ O ₃ (molar ratio) = 2.0

Aluminum sulfate: hydrated aluminum sulfate, commercially available products

Alkali metal sulfates: sodium sulfate, anhydrides, commercial products

Aromatic sulfonate α: β-NS, powder type, commercially available product

How to measure

Cure Time: The mortar was kneaded using a material containing coarse aggregate not present in the sprayed concrete, and the cure time was measured according to the "Quality Standard for Accelerator for Spray Concrete (JSCED-102)".

Compressive strength: measured at 20 ° C. The prepared hard curing sprayed concrete was sprayed into a 25 cm wide x 25 cm long pullout mold and 50 cm wide x 50 cm long x 20 cm thick. Using the test sample of the pull-out template, the initial strength after 3 hours was measured. The pullout strength was obtained by covering the pins with fast curing sprayed concrete from the front surface of the pullout mold and pulling out the pin from the backside of the mold. The compressive strength was calculated by the following equation:

Compressive strength = pullout strength x 4 / surface area of the test sample

After at least one day, the test sample was measured by a 20 ton pressure gauge, using a test sample of 5 cm diameter x 10 cm length sampled from a mold 50 cm wide x 50 cm long x 20 cm thick.

Bounce Rate: Rapid hardening sprayed concrete was sprayed for 10 minutes at a pressurized injection rate of 4 m ³ / hr into a model tunnel of 3.5 m by 2.5 m in height made of an arcuate iron plate. Thereafter, the bounce rate was calculated by the following formula:

Bounce Rate = Weight of hardened sprayed concrete dropped without depositing in the model tunnel / Weight of hardened sprayed concrete sprayed in the model tunnel x 100 (%)

Test Example Number Aluminum sulfate Curing time (minutes) Compressive strength (N / mm ² ) Bounce rate (%) Remarks start complete 3 hours 1 day 28 days 1-1 0 5 22 1.8 14.2 52.5 22.1 Comparative example 1-21-31-41-51-61-7 510254045100 2 <1 <1 <1 <1 <1 742335 2.83.24.84.64.64.2 16.820.423.120.619.817.6 53.853.753.953.452.349.0 16.813.112.012.610.914.5 EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE EXAMPLE

^* Represents the amount of aluminum sulphate a calcium aluminate per 100 parts by weight parts by weight calculated as the anhydride.

Test Example 2

The test and evaluation were carried out in 100 parts by weight of calcium aluminate as identified in Table 2, 25 parts by weight of aluminum sulfate calculated as anhydride, 18 parts by weight of alkali metal sulfate per 100 parts by weight of accelerator containing calcium aluminate, aluminum sulfate and alkali metal sulfate. Parts and powdered accelerators prepared by mixing 2 parts by weight of aromatic sulfonate α per 100 parts by weight of accelerator were used in the same manner as in Test Example 1. The results are shown in Table 2.

Used materials

Calcium aluminate ②: mainly for compositions containing C ₁₂ A ₇ , blind value: 6,000 cm ² / g, calcia material and alumina material are mixed in a predetermined ratio and melted with a high frequency induction furnace, and then 40 Annealed to a% vitrification rate and then milled. CaO / Al ₂ O ₃ (molar ratio) = 2.0

Calcium aluminate ③: mainly corresponds to the composition containing C ₁₂ A ₇ , blind value: 6,000 cm ² / g, calcia material and alumina material are mixed in a predetermined ratio and melted with a high frequency induction furnace, and then 60 Annealed to a% vitrification rate and then milled. CaO / Al ₂ O ₃ (molar ratio) = 2.0

Calcium aluminate ④: mainly applicable to the composition containing C ₁₂ A ₇ , blind value: 6,000 cm ² / g, calcia material and alumina material were mixed in a predetermined ratio, melted with a high frequency induction furnace, and then 80 It was quenched to a% vitrification rate and then milled. CaO / Al ₂ O ₃ (molar ratio) = 2.0

Test Example Number Aluminum sulfate Curing time (minutes) Compressive strength (N / mm ² ) Bounce rate (%) start complete 3 hours 1 day 28 days 2-12-22-31-4 ②③④① <1 <1 <1 <1 4332 3.03.54.24.8 15.919.221.323.1 52.253.053.853.9 14.713.512.812.0

Test Example 3

The tests and evaluations were performed based on 100 parts by weight of calcium aluminate, which was identified in Table 3, 25 parts by weight of aluminum sulfate, calculated as anhydride, alkali metal sulfate 18 per 100 parts by weight of accelerator containing calcium aluminate, aluminum sulfate and alkali metal sulfate. It carried out in the same manner as in Test Example 1, except that a powdery accelerator prepared by mixing 2 parts by weight of aromatic sulfonate α per 1 part by weight and 100 parts by weight of accelerator was used. The results are shown in Table 3.

Used materials

Calcium aluminate (5): The calcia material and the alumina material were mixed in a predetermined ratio, melted with a high frequency induction furnace, and then quenched to have a vitrification rate of 100%, and then ground. Amorphous, blind value: 6,000 cm ² / g, CaO / Al ₂ O ₃ (molar ratio) = 1.5

Calcium aluminate (6): The calcia material and the alumina material were mixed at a predetermined ratio, melted with a high frequency induction furnace, quenched to have a vitrification rate of 100%, and then ground. Amorphous, blind value: 6,000 cm ² / g, CaO / Al ₂ O ₃ (molar ratio) = 1.7

Calcium aluminate ⑦: The calcia material and the alumina material were mixed at a predetermined ratio, melted with a high frequency induction furnace, quenched to have a vitrification rate of 100%, and then ground. Amorphous, blind value: 6,000 cm ² / g, CaO / Al ₂ O ₃ (molar ratio) = 2.5

Calcium aluminate ⑧: The calcia material and the alumina material were mixed at a predetermined ratio, melted with a high frequency induction furnace, and then quenched to have a vitrification rate of 100%, and then ground. Amorphous, blind value: 6,000 cm ² / g, CaO / Al ₂ O ₃ (molar ratio) = 3.0

Test Example Number Calcium aluminate Curing time (minutes) Compressive strength (N / mm ² ) Bounce rate (%) start complete 3 hours 1 day 28 days 3-13-21-43-33-4 ⑤⑥①⑦⑧ 2 <1 <1 <1 <1 53223 2.23.14.84.24.0 18.620.023.122.220.4 54.254.053.953.453.1 15.413.912.012.812.9

Test Example 4

Tests and evaluations are given in parts by weight in Table 4 per 100 parts by weight of the accelerator containing 100 parts by weight of calcium aluminate①, 25 parts by weight of aluminum sulfate, calcium aluminate, aluminum sulfate and alkali metal sulfate, calculated as anhydride. It was carried out in the same manner as in Test Example 1 except for using a metal sulfate and a powder promoter prepared by mixing 2 parts by weight of aromatic sulfonate α per 100 parts by weight of the accelerator. The results are shown in Table 4.

Test Example Number Alkali Metal Sulfate Curing time (minutes) Compressive strength (N / mm ² ) Bounce rate (%) Remarks start complete 3 hours 1 day 28 days 4-1 0 2 20 1.2 10.3 53.4 18.4 Comparative example 4-2 10 2 5 3.7 15.7 55.2 16.1 Example 4-3 15 <1 4 4.4 19.3 54.7 14.3 Example 1-4 18 <1 2 4.8 23.1 53.9 12.0 Example 4-4 20 <1 2 5.2 23.7 51.2 11.6 Example 4-5 30 3 5 3.2 24.5 50.1 11.5 Example

* Alkali metal sulphate is expressed in parts by weight per 100 parts by weight of accelerator containing calcium aluminate, aluminum sulphate and alkali metal sulphate.

Test Example 5

Tests and evaluations were carried out in powder promoters prepared by mixing 18 parts by weight of alkali metal sulfate and 2 parts by weight of aromatic sulfonate α per 100 parts by weight of accelerators containing aluminum sulfate and alkali metal sulfate without the use of calcium aluminate. Except that using was carried out in the same manner as in Test Example 1. The results are shown in Table 5. Measurement method Low temperature pressurization strength: It measured similarly to the measurement of pressurization strength except having measured at 10 degreeC.

Test Example Number Curing time (minutes) Compressive strength (N / mm ² ) Low temperature compressive strength (N / mm ² ) Remarks start complete 3 hours 1 day 28 days 1 day 28 days 5-1 7 45 0.9 20.7 49.6 9.3 52.1 Comparative example 1-4 <1 2 4.8 23.1 53.9 14.4 55.7 Example

Test Example 6

Tests and evaluations were performed based on 100 parts by weight of calcium aluminate ①, 18 parts by weight of alkali metal sulfate per 100 parts by weight of accelerator containing 25 parts by weight of aluminum sulfate, calcium aluminate, aluminum sulfate and alkali metal sulfate, and It was carried out in the same manner as in Test Example 1 except for using a powder promoter prepared by mixing the aromatic sulfonate α in an amount shown in parts by weight in Table 6 per 100 parts by weight of the accelerator. The results are shown in Table 6.

Used materials

Aromatic sulfonate β: β-alkylnaphthalene sulfonate-formaldehyde condensate, powder form, commercially available product

Aromatic sulfonate γ: bisphenol A sulfonate-formaldehyde condensate γ, powder type, commercially available product.

Aromatic sulfonate δ: phenolsulfonic acid, powder, commercially available product.

How to measure

Amount of dust: curing properties spraying concrete was sprayed for 10 minutes using a pressurized injection speed of 4m ³ / hour in the model of the tunnel height of 3.5m, 2.5m width made of a steel plate to arcuate. Subsequently, the amount of dust was measured at a predetermined position 3 meters away from the spray position, and expressed as an average value of the measured values.

Test Example Number Aromatic sulfonates Bounce rate (%) Dust amount (mg / m ³ ) Compressive strength (N / mm ² ) 3 hours 1 day 28 days 6-1 -0 19.4 5.8 5.1 23.9 55.7 6-2 α0.05 16.5 3.4 5.0 23.6 55.0 6-3 α0.1 14.1 3.1 4.9 23.3 54.5 1-4 α2.0 12.0 2.7 4.8 23.1 53.9 6-4 α3.0 11.7 2.6 3.2 29.2 50.3 6-5 α5.0 13.5 3.3 3.1 28.1 49.0 6-6 β2.0 15.1 3.4 4.9 23.4 54.1 6-7 γ2.0 14.6 3.6 4.7 23.5 54.3 6-8 δ2.0 16.5 4.5 3.7 21.6 52.4

Aromatic sulfonates are expressed in amounts by weight per 100 parts by weight of accelerator.

Test Example 7

Spraying concrete is prepared by adding PAO in an amount as shown in Table 7 per 100 parts by weight of cement, and adding a fibrous material in an amount of 1.0 part by volume per 100 parts by volume of the spraying concrete containing the fibrous material. While concrete is pressurized, 18 parts by weight of alkali metal alcohol per 100 parts by weight of accelerator containing 100 parts by weight of calcium aluminate ①, 15 parts by weight of aluminum sulfate, calcium aluminate, aluminum sulfate and alkali metal sulfate, calculated as anhydride. Tests and evaluations were carried out in the same manner as in Test Example 1, except using a powder and a powder promoter prepared by mixing 2 parts by weight of aromatic sulfonate α per 100 parts by weight of the accelerator. The results are shown in Table 7.

Test Example Number PAO Bounce rate (%) Dust amount (mg / m ³ ) 7-1 0 20.1 6.1 7-2 0.001 14.6 4.4 7-3 0.005 13.7 3.5 1-4 0.02 12.0 2.7 7-4 0.1 11.0 2.1 7-5 0.2 13.7 3.9

* PAO is expressed in parts by weight per 100 parts by weight of cement.

Test Example 8

Spraying concrete is prepared by adding PAO in an amount of 0.02 parts by weight per 100 parts by weight of cement, and adding the fibrous material in an amount shown in Table 8 per 100 parts by volume of the spraying concrete containing the fibrous material. 18 parts by weight of alkali metal sulphate per 100 parts by weight of a promoter containing 100 parts by weight of calcium aluminate①, 25 parts by weight of aluminum sulfate, calcium aluminate, aluminum sulfate and alkali metal sulfate, as calculated by anhydride, and Tests and evaluations were carried out in the same manner as in Test Example 1, except that a powder promoter prepared by mixing 2 parts by weight of aromatic sulfonate α per 100 parts by weight of the accelerator was used. The results are shown in Table 8.

How to measure

Impact resistance: After 1 hour, the hardened spray concrete is cut into a width of 20 cm x 20 cm x 1 cm thick, placed on a flat, standard sand, and then 200 g of spheres are dropped at a height of 50 cm. Destroyed by five drops was represented by ×, unbroken but cracked by △, and broken and unbroken by zero.

Test Example Number Fibrous material Impact resistance 8-1 0 × 8-2 0.1 △ 8-3 0.3 O 1-4 1.0 O 8-4 1.2 O 8-5 1.5 △

* Fibrous material is expressed in volume parts per 100 parts by weight of sprayed concrete containing fibrous material.

Test Example 9

The tests and evaluations were performed based on 100 parts by weight of calcium aluminate ①, 18 parts by weight of alkali metal sulfate per 100 parts by weight of accelerator containing 25 parts by weight of aluminum sulfate, calcium aluminate, aluminum sulfate and alkali metal sulfate, and A powder accelerator prepared by mixing 2 parts by weight of aromatic sulfonate α per 100 parts by weight of the accelerator was pressurized with compressed air, and the slurry water was supplied into the passage in a quantity shown in Table 9 per 100 parts by weight of the accelerator. It is added through a hole formed in various parts around the branch to form an accelerator slurry, and the accelerator slurry is pressurized and mixed with the spraying concrete pressurized from the other branch of the Y branch pipe to form a hardening sprayed concrete. Except that it was carried out in the same manner as in Test Example 1. The results are shown in Table 9.

Test Example Number Slurry water Compressive strength (N / mm ² ) Dust amount (%) 3 hours (mg / m ³ ) 28 days 1-4 0 4.8 23.1 53.9 2.7 9-1 30 3.1 20.3 48.1 1.1 9-2 50 3.4 19.6 47.0 0.9 9-3 70 3.7 19.2 46.4 0.8 9-4 80 3.7 19.0 45.8 0.8

The number of slurries is expressed in amounts by weight per 100 parts by weight of accelerator.

Test Example 10

The tests and evaluations were performed based on 100 parts by weight of calcium aluminate ①, 18 parts by weight of alkali metal sulfate per 100 parts by weight of accelerator containing 25 parts by weight of aluminum sulfate, calcium aluminate, aluminum sulfate and alkali metal sulfate, and One of the Y-branched tubes provided in the passage by pressurizing and ejecting the powder promoter prepared by mixing 2 parts by weight of aromatic sulfonate α per 100 parts by weight of the accelerator with compressed air and slurry water in an amount of 70 parts by weight per 100 parts by weight of the accelerator. Through a hole formed in various parts around the to form an accelerator slurry, and the accelerator slurry is pressurized and mixed with the sprayed concrete pressurized from the other branch of the Y branched tube to form a hardening sprayed concrete. It was carried out in the same manner as in Test Example 1 except that. The results are shown in Table 10.

How to measure

pH: The promoter slurry was diluted 10 times with water and the pH of the diluted product was shown.

Pressurized injection property: After spraying the sprayed concrete with a concrete pump for 20m, it is mixed with an accelerator to form a fast curing concrete, and the fast curing concrete is sprayed for 5 minutes. In the case where no blockage is observed in the Y branched pipe or in the pipe, it is indicated by 0, and when it is easy to be clogged, it is indicated by △.

Settlement (sagging): curing properties thereby spraying concrete was sprayed for 10 minutes using a pressurized injection speed of 4m ³ / hour in the height and width of 3.5m 2.5m made of a steel plate of the tunnel arch model. Next, when the concrete for hardening spraying does not settle down from the side wall of a model tunnel, it represented by 0, and when concrete settled slightly, it represented by (triangle | delta), and when concrete subsided considerably, it represented by x.

Test Example Number Curing time (minutes) Low temperature compressive strength (N / mm ² ) pH Bounce rate (%) Pressurized Injection Characteristics subsidence start complete 1 day (%) 9-3 <1 3 19.2 46.4 5 10.4 0 0

As mentioned above, the spray material of the present invention can be used to reduce the bounce rate upon spraying of the fast curing cement concrete. In addition, the development of high intensity is expected for initial strength and long term strength, and the spray thickness can be thinned. In addition, the operating cost is reduced, and after spraying, high strength is obtained immediately, thereby improving stability.

Claims (12)

Accelerators containing calcium aluminate, aluminum sulfate and alkali metal sulphate. The accelerator according to claim 1, wherein the alkali metal sulfate is 10 to 30 parts by weight based on 100 parts by weight of the accelerator. The promoter according to claim 1 or 2, wherein CaO / Al ₂ O ₃ (molar ratio) of calcium aluminate is 1.5 to 3.0. The promoter according to claim 1 or 2, further comprising an aromatic sulfonic acid or an aromatic sulfonate-formaldehyde condensate, or a mixture thereof. The accelerator according to claim 1 or 2, which is in powder form. The accelerator according to claim 1 or 2, which further contains water. 7. The promoter of claim 6 having a pH of less than 7. The promoter according to claim 1 or 2, wherein the ratio of vitrification of calcium aluminate is at least 40%. Cement concrete containing cement, and a spray material containing an accelerator as defined in claim 1 or 2 mixed with the cement concrete. 10. The spraying material according to claim 9, wherein the cement concrete further contains polyalkylene oxide. 10. The spraying material according to claim 9, further comprising a fiber material. A spraying method comprising pressurizing an accelerator as defined in claim 1 or 2 with compressed air to mix with cement concrete.