Foaming quick-setting agent and spraying method

Abstract

To provide a foaming quick-setting agent that enables improvement of workability by suppressing the generation of dust generated during spraying work in tunnels or the like, is capable of providing high quick setting even under conditions where there is spring water or where the ground surface has deteriorated, and can be applied to places where long-term strength development is required.SOLUTION: A foaming quick-setting agent of the type used by mixing a powder admixture with a liquid quick-setting agent is provided in which the powder admixture contains (a) a calcium aluminate powder having a SiO2 content of 7 mass% or less, a vitrification ratio of 30-98 mass%, and a sulfur content of 0.007-0.5%, and (b) an alkali carbonate powder; the calcium aluminate powder is contained in the amount of at least 20 pts.mass relative to 100 pts.mass of the powder admixture; the alkali carbonate powder is contained in the amount of 0.1 pts.mass or more relative to 100 pts.mass of the powder admixture; and liquid quick-setting agent contains aluminum sulfate having a pH of 1 to 5 in the amount of 20 pts.mass or more relative to 100 pts.mass of the liquid quick-setting agent.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a foaming quick-setting agent and a spraying method.

Background Art

[0002] Conventionally, for preventing the collapse of exposed natural ground such as tunnel excavation, a spraying method of quick-setting concrete in which a quick-setting agent is blended with concrete has been carried out (Patent Document 1). In this method, usually, sprayed concrete is prepared at a metering and mixing plant for cement, aggregate, water, etc. installed at the excavation work site, transported by an agitator truck, pumped by a concrete pump, and mixed with a quick-setting agent pumped from the other side through a confluence pipe provided on the way, and then sprayed onto the natural ground surface as quick-setting sprayed concrete until it reaches a predetermined thickness.

[0003] As quick-setting agents that have been conventionally used, mixtures such as calcium aluminate, alkali metal aluminate, and alkali metal carbonate, mixtures such as burnt alum, alkali metal aluminate, and alkali metal carbonate, mixtures of calcium aluminate and 3CaO·SiO2, mixtures of slaked lime, alkali metal aluminate, and alkali metal carbonate, etc. are known (Patent Documents 2 to 5). These quick-setting agents have the function of accelerating the setting of cement, and all are mixed with cement concrete and sprayed onto the natural ground surface.

[0004] The method of adding the quick-setting agent was usually a method in which the amount of dust increased for powder mixing by air transportation. Therefore, the working environment may deteriorate, and it is necessary to wear protective glasses, dust masks, etc. during spraying, and a method with less dust amount has been demanded. As a method with less dust generation, a method has been proposed in which the quick-setting agent is slurried and added and mixed with cement concrete, and then a solution of alkali metal aluminate is separately pumped, mixed, and sprayed (Patent Document 6). This method has a problem that since a highly alkaline liquid is used, it is difficult to handle, and protective glasses, gloves, etc. are required during spraying, resulting in a decrease in workability.

[0005] On the other hand, a rapid hardening construction method has been proposed to improve the working environment by slurrying the accelerating agent and adding alum salts to the cement concrete (Patent Document 7). In addition, a rapid hardening construction method with improved rapid hardening property has been proposed in terms of improving workability, reducing dust effect, and shortening the construction period (Patent Document 8).

[0006] However, a rapid hardening agent with a lower pH value than a rapid hardening agent obtained by mixing calcium aluminate with alkali metal aluminate, alkali metal carbonate, etc., and a weakly alkaline, preferably neutral or weakly acidic rapid hardening agent is required. To solve this problem, as a liquid rapid hardening agent, those mainly composed of basic aluminum salts or organic carboxylic acids (Patent Document 9), those mainly composed of aluminum sulfate or alkanolamine (Patent Document 10), and those mainly composed of a basic aqueous solution of aluminum, lithium silicate, and lithium aluminate (Patent Document 11), etc. are used. This liquid rapid hardening agent is difficult to obtain initial strength development, and there was a concern that it would peel off when thickly sprayed in the tunnel when compared with a conventional rapid hardening agent mainly composed of calcium aluminate (Patent Documents 12 and 13).

[0007] Therefore, a spraying material has been developed which is characterized by adding any one or two or more selected from the group of inorganic compounds consisting of an acidic liquid rapid hardening agent mainly composed of aluminum or sulfur and powdered aluminum sulfate, sulfate, aluminate, and hydroxide (Patent Document 14). In addition, a foaming rapid hardening agent obtained by mixing a liquid rapid hardening agent and alkali carbonates has been developed (Patent Document 15).

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Patent Document 11

Patent Document 12

Patent Document 13

Patent Document 14

Patent Document 15

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, the foaming quick-setting agent of Patent Document 15 has strong reactivity with cement and exhibits high strength development, but it is desirable to further improve its applicability to locations where long-term durability improvement is required.

[0010] The present invention provides a foaming quick-setting agent that can suppress the generation of dust generated during spraying work such as in tunnels, improve workability, obtain high quick-setting properties even under conditions where water gushing or the ground surface deteriorates, and can be applied to locations where long-term strength development is required.

Means for Solving the Problems

[0011] As a result of intensive research to solve the above problems, the inventors have found that the above problems can be solved by combining a specific powder admixture and a specific liquid accelerator, and have thus completed the present invention. That is, the present invention is as follows.

[0012] [1] A foaming accelerator that is used by mixing a powder admixture and a liquid accelerator, wherein the powder admixture contains calcium aluminate powder and alkali carbonate powder having an SiO2 content of 7% by mass or less, a vitrification rate of 30 to 98% by mass, and a sulfur content of 0.007 to 0.5%, the calcium aluminate powder is contained in an amount of 20 parts by mass or more per 100 parts by mass of the powder admixture, the alkali carbonate is contained in an amount of 0.1 part by mass or more per 100 parts by mass of the powder admixture, and the liquid accelerator is a foaming accelerator containing 20 parts by mass or more of aluminum sulfate having a pH of 1 to 5 per 100 parts by mass of the liquid accelerator. [2] The foaming accelerator according to [1], wherein the CaO / Al2O3 molar ratio of the calcium aluminate powder is 1.8 to 2.9. [3] The foaming accelerator according to [1] or [2], wherein the calcium aluminate powder contains 1 to 40% by mass of 3CaO·Al2O3. [4] The foaming accelerator according to any one of [1] to [3], wherein the alkali carbonate powder is sodium carbonate powder. [5] A spraying method in which the foaming accelerator according to any one of [1] to [4] is added to the concrete immediately before the concrete is sprayed, wherein the powder admixture is added in an amount of 3 parts by mass or more per 100 parts by mass of the cement in the concrete, and the liquid accelerator is added in an amount of 4 parts by mass or more per 100 parts by mass of the cement in the concrete. [Advantages of the Invention]

[0013] According to the present invention, it is possible to suppress the generation of dust generated during spraying work such as in tunnels, improve workability, obtain high accelerating properties even under conditions where water gushing or the ground surface deteriorates, and provide a foaming accelerator that can be applied to locations where long-term strength development is required.

Mode for Carrying Out the Invention

[0014] Hereinafter, the present invention will be described in detail. Parts and percentages in this specification are shown on a mass basis unless otherwise specified.

[0015] [1] Foaming type quick-setting agent The foaming type quick-setting agent according to one embodiment (this embodiment) of the present invention is a two-component type foaming type quick-setting agent composed of a powder admixture and a liquid quick-setting agent, and these are mixed and used. For example, the powder admixture and the liquid quick-setting agent are separate before use, and foaming occurs when these are mixed simultaneously, or when one is mixed into concrete or the like and then the other is mixed.

[0016] <Powder admixture> The powder admixture according to this embodiment contains calcium aluminate powder and alkali carbonate powder. These will be described below.

[0017] (Calcium aluminate powder) The calcium aluminate powder has a SiO2 content of 7 mass% or less, a vitrification rate of 30 to 98 mass%, and a sulfur content of 0.007 to 0.5%.

[0018] If the SiO2 content exceeds 7%, the quick-setting property deteriorates, which is not preferable. 6% or less is preferable, and 5% or less is more preferable. Also, considering that vitrification does not fall below 30%, it is preferably 0.1% or more, and more preferably 1% or more. The SiO2 content can be measured by fluorescent X-ray. Also, the SiO2 content can be adjusted by adjusting the amount of SiO2 in the raw materials when producing the calcium aluminate powder, or by newly adding SiO2.

[0019] Also, if the vitrification rate is less than 30% or exceeds 98%, the quick-setting property deteriorates. The vitrification rate is preferably 40 to 95%. Here, the vitrification rate can be calculated by measuring in advance the main peak area S of the crystalline mineral by powder X-ray diffraction of the sample before heating, heating at 1000 °C for 2 hours, then slowly cooling at a cooling rate of 1 to 10 °C / min, obtaining the main peak area S0 of the crystalline mineral after heating by powder X-ray diffraction, and further using these values of S0 and S and the following formula. Vitrification rate (%) = 100×(1 - S / S0) Note that the vitrification rate can be adjusted to a desired range, for example, by the heating temperature and the cooling rate after heating when producing calcium aluminate powder.

[0020] Furthermore, when the sulfur content is less than 0.007%, the amount of foaming may decrease when mixed with aluminum sulfate powder, and when it exceeds 0.5%, it tends to inhibit the quick-setting property, which is not preferable. The sulfur content is preferably 0.01 to 0.3%. The sulfur content can be measured by fluorescent X-ray. Also, the sulfur content can be adjusted by adjusting the amount of sulfur in the raw materials when producing calcium aluminate powder or by adding a sulfur source.

[0021] Here, calcium aluminate (hereinafter, also referred to as CA or CAs) is a general term for compounds mainly composed of CaO and Al2O3 and having hydration activity, and a part of CaO and / or Al2O3 is replaced by alkali metal oxides, alkaline earth metal oxides, silicon oxide, titanium oxide, iron oxide, alkali metal halides, alkaline earth metal halides, alkali metal sulfates, and alkaline earth metal sulfates, etc., or a substance in which these are slightly solid-dissolved in those mainly composed of CaO and Al2O3.

[0022] Note that the calcium aluminate powder used in this embodiment may be contaminated with trace amounts of alkali metals and / or alkaline earth metals from industrial raw materials, and there is a possibility that CAs containing these alkali metals and / or alkaline earth metals are partially generated, but it is not restricted by the presence of these small amounts of alkali metals and / or alkaline earth metals in any way.

[0023] The calcium aluminate powder is preferably alkaline, and more preferably has a pH of 10 to 14. By being alkaline (especially with a pH of 10 to 14), it is easier to exhibit the characteristics of the calcium aluminate powder. Note that the pH can be measured by collecting the supernatant liquid prepared from an aqueous solution five times or more the amount of the calcium aluminate powder and water, and using a general pH measurement method typified by the pH measurement method of JIS Z8802.

[0024] The CaO / Al2O3 molar ratio of the calcium aluminate powder is not particularly limited, but considering the very early strength development property, the molar ratio is preferably 1.8 to 2.9. When the molar ratio is 1.8 or more, the very early setting property can be improved, and when it is 2.9 or less, it is easier to obtain good long-term strength development property. The CaO / Al2O3 molar ratio is more preferably 2.2 to 2.8.

[0025] Also, it is preferably contained 1 to 40% of 3CaO·Al2O3 in the calcium aluminate powder, and more preferably 5 to 30%. By containing 1 to 40%, 3CaO·Al2O3 can be quantified by X-ray diffraction. Also, the content rate of 3CaO·Al2O3 can be adjusted by heat-treating at a raw material ratio close to a CaO / Al2O3 molar ratio of 2.8, or further adjusting the vitrification rate to 95% or less.

[0026] The Blaine specific surface area of the calcium aluminate powder (hereinafter sometimes simply referred to as "Blaine") is preferably 4000 to 8000 cm 2 / g, and more preferably 5000 to 7000 cm 2 / g. By being 4000 to 8000 cm 2 / g, it is easier to obtain early strength development property and can improve the workability of the mortar and / or concrete during spraying. The brain specific surface area is measured based on the specific surface area test described in JIS R 5201 "Physical Testing Methods for Cement".

[0027] The calcium aluminate powder contains 20 parts by mass or more, preferably 20 to 90 parts, and more preferably 30 to 70 parts in 100 parts by mass of the powder admixture. If the calcium aluminate is less than 20 parts, the very early strength may decrease and the rebound rate may increase. If it exceeds 90 parts, the long-term strength will decrease.

[0028] As a method for producing the calcium aluminate powder for the quick-setting agent according to this embodiment, there is a method of mixing a raw material containing calcia and a raw material containing alumina, etc., and performing heat treatment such as firing in a kiln or melting in an electric furnace. When mixing these raw materials, it is also possible to blend a raw material containing an SiO2 component or a raw material containing a sulfur component, and there are no particular restrictions on the raw materials.

[0029] (Alkali carbonate powder) The alkali carbonate powder promotes the initial setting of cement and the development of strength, and examples include sodium carbonate, potassium carbonate, lithium carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate. Among these, sodium carbonate powder is preferable in terms of promoting initial setting and storage stability. In terms of foaming properties, the Blaine value of the alkali carbonate powder is preferably 300 g / cm 3 or more, and more preferably 500 g / cm 3 or more. When it is 300 g / cm 3 or more, good foaming is more likely to be promoted.

[0030] The alkali carbonate powder contains 0.1 part or more, preferably 0.1 to 10 parts, and more preferably 0.2 to 7.5 parts with respect to 100 parts of the powder admixture. If the alkali carbonate powder is less than 0.1 part, foaming does not occur well, and due to solidification in the pipe, the mixability with concrete decreases, and the strength development from the very beginning decreases.

[0031] The mass mixing ratio of calcium aluminate powder to alkali carbonate powder (calcium aluminate powder / alkali carbonate powder) is preferably from 200 / 1 to 2 / 1, more preferably from 150 / 1 to 3 / 1, from the viewpoints of improving the very early strength development due to the activity of the powder admixture derived from calcium aluminate and alkali carbonate, enhancing the mixability with concrete due to the foaming of calcium aluminate and alkali carbonate powder, and preventing pipe solidification.

[0032] In addition to the above components, the powder admixture may be blended with materials generally used as quick-setting agents for sprayed concrete, such as calcium sulfate. Also, inorganic acids such as carbonic acid, nitric acid, sulfuric acid, phosphoric acid, boric acid, and hydrofluoric acid, and salts thereof (sodium, potassium, lithium, calcium, magnesium, aluminum), and organic acids such as monocarboxylic acid, dicarboxylic acid, polycarboxylic acid, oxycarboxylic acid, and amino acid, and salts thereof (sodium, potassium, lithium), etc. can be used in combination. Among these, dicarboxylic acid, oxycarboxylic acid, and salts thereof can be used in combination from the viewpoints of solubility in water and handling.

[0033] <Liquid quick-setting agent> The liquid quick-setting agent according to this embodiment contains 20 parts or more of aluminum sulfate exhibiting a pH of 1 to 5 in 100 parts of the liquid quick-setting agent. When the content of the aluminum sulfate is less than 20 parts, the very early strength development decreases and poor adhesion of the concrete occurs. The content of the aluminum sulfate is preferably from 20 to 35, more preferably from 24 to 30. Also, from the viewpoint of setting properties, an aqueous solution of aluminum sulfate is preferred as the liquid quick-setting agent.

[0034] The aqueous solution of aluminum sulfate is an acidic aqueous solution obtained by dissolving aluminum sulfate powder in water or by the reaction of aluminum hydroxide and sulfuric acid. The hardening rate of the hydration product can be increased by the pH being in the acidic region. The concentration of the aqueous solution of aluminum sulfate is preferably from 20 to 35%. Aluminum sulfate can be used in either anhydrous or hydrated form and is not particularly limited.

[0035] Here, the foaming quick-setting agent is one that foams itself when it comes into contact with water, cement concrete, etc. That is, it becomes a foamed quick-setting agent. This foaming generates hydrogen sulfide from the sulfur component derived from calcium aluminate and aluminum sulfate, and carbon dioxide gas from alkali carbonate and aluminum sulfate. When added to concrete, the generation of hydrogen sulfide and carbon dioxide gas stops simultaneously, so there is no impact on the human body. Since the quick-setting agent itself foams, there is no blockage trouble when mixing and merging with concrete, so there are fewer dangerous operations and safe spraying construction can be carried out. From the perspective of workability, it is preferably substantially free of alkali aluminate. Here, "substantially free of alkali aluminate" means that when measured by X-ray diffraction, the content is on the order of % and is 0.

[0036] The mass mixing ratio of the powder admixture to the liquid quick-setting agent (powder admixture: liquid quick-setting agent) is preferably 4:1 to 1:5, and more preferably 3:1 to 1:4, from the viewpoints of adjusting the foaming quick-setting agent, improving the early strength development property, reducing the pipe solidification due to foaming, and enhancing the mixability with concrete.

[0037] [2] Spraying method The spraying method according to an embodiment of the present invention is a spraying method in which the above-described foaming quick-setting agent of the present invention is added to concrete immediately before the concrete is sprayed, wherein the powder admixture is added in an amount of 3 parts or more per 100 parts of cement in the concrete, and the liquid quick-setting agent is added in an amount of 3 parts or more per 100 parts of cement in the concrete.

[0038] If the addition amount of the powder admixture is less than 3 parts, the early strength development property will decrease. The addition amount of the powder admixture is preferably 3 to 20 parts, and more preferably 4 to 17 parts. Also, if the addition amount of the liquid quick-setting agent is less than 3 parts, the early strength development property will decrease. The addition amount of the liquid quick-setting agent is preferably 4 to 14 parts, and more preferably 5 to 12 parts.

[0039] The cement used in the concrete into which the foaming type quick-setting agent according to this embodiment is to be incorporated and mixed is not particularly limited, and examples include various Portland cements such as ordinary, early-strength, super-early-strength, medium-heat, and low-heat Portland cements, filler cements obtained by mixing blast furnace slag, fly ash, and fine limestone powder with these Portland cements, and environment-friendly cements (eco-cements) manufactured using incinerated ash from municipal waste and incinerated ash from sewage sludge as raw materials. It is also possible to use these after pulverizing them into fine powder. The ratio of the mixture to the cement in the blended cement is not particularly limited, and those obtained by mixing these admixtures more than assumed in JIS can also be used.

[0040] The concrete used in the present invention contains cement and aggregate, and the aggregate preferably has a low water absorption rate and high aggregate strength. The aggregate is not particularly limited as long as it can be sprayed. As fine aggregate, river sand, mountain sand, sea sand, lime sand, silica sand, etc. can be used, and as coarse aggregate, river gravel, mountain gravel, lime gravel, etc. can be used, and crushed sand and crushed stone can also be used.

[0041] In addition, as the spraying method using the foaming type quick-setting agent of the present invention, various spraying methods according to required physical properties, economic efficiency, workability, etc. are possible. For example, both the dry spraying method and the wet spraying method are possible.

Examples

[0042] 「Experimental Example 1」 (1) Powder admixture The following materials were used as the powder admixture. (Calcium aluminate powder) Calcium carbonate, aluminum oxide, silica, and sulfur were mixed at various ratios (including the case where silica etc. is 0%), melted at 1600°C in an electric furnace, the cooling rate was adjusted, pulverized with a ball mill, and then classified to obtain a calcium aluminate (CA) powder having a Blaine value of about 8,000 cm 2 / g and having the silica content, vitrification rate, sulfur content, and CaO / Al2O3 (molar ratio) shown in Table 1 was produced.

[0043]

Table 1

[0044] 60 parts of calcium aluminate powder of the type shown in Table 1, 5 parts of alkali carbonate A, and 35 parts of calcium sulfate powder were mixed to produce a powder admixture. (Alkali carbonate powder) · Alkali carbonate A: Commercially available sodium carbonate (BET specific surface area 800 cm 2 / g) (Calcium sulfate powder) · Calcium sulfate: Commercially available anhydrous calcium sulfate (BET specific surface area 4,500 cm 2 / g)

[0045] (2) Liquid accelerator The following materials were used as the liquid accelerator. · Liquid accelerator α: Reagent-grade aluminum sulfate was dissolved in pure water and adjusted to a concentration of 27% (pH 2.0)

[0046] [Mortar test] 800 g of cement, 2000 g of fine aggregate, and 480 g of water (tap water) were charged into a mortar mixer, kneaded to prepare mortar. For every 100 parts of cement, 6 parts of the powder admixture of the type shown in Table 1 and 6 parts of liquid accelerator α were quickly charged into the mortar and kneaded to prepare quick-setting mortar. Thereafter, the setting time and compressive strength of the mortar were measured. The results are shown in Table 3. Note that ordinary Portland cement, a commercially available product with a Blaine value of 3,200 cm 2 / g and a specific gravity of 3.16 was used, and the fine aggregate was river sand from the Himekawa water system in Iwamizawa City, Niigata Prefecture, in the surface-dry state, with a specific gravity of 2.62 and a maximum particle size of 5 mm.

[0047] <Measurement method> Setting time: Measured in accordance with the standard of the Japan Society of Civil Engineers "Quality Standard for Quick-Setting Agents for Sprayed Concrete (JSCE D-102)". Compressive strength (3 hours, 1 day, 28 days): Measured in accordance with JIS R 5201.

[0048] [Sprayed concrete test] Concrete with the fresh properties and concrete mix shown in Table 2 was adjusted, and under the conditions of a spraying pressure of 0.4 MPa and a spraying speed of 12 m 3 / h, it was pumped by a concrete pump "MKW-25SMT", and the pump pressure during pumping was monitored. On the other hand, with respect to 100 parts of cement, under the condition of a pumping pressure of 0.5 MPa, the liquid accelerator α was quantitatively transported by a liquid pump so that it became 6 parts, and the powder assistant was 6 parts. During the process, it was transported by air, and from the other side, the powder assistant (see Table 3) was transported by air using "NATM concrete". The liquid accelerator and the powder assistant were mixed and joined together before merging with the concrete to adjust the foaming-type accelerator. This accelerator was mixed into the concrete pumped from the other side of the Y-shaped pipe to make sprayed concrete. For this rapidly setting sprayed concrete, the concrete compressive strength, rebound rate, dust amount, and mixing property evaluation were measured. Also, after spraying, the accelerator side of the Y-shaped pipe was checked to confirm the solidification status. Shown in Table 3.

[0049] <Concrete mix>

Table 2

[0050] Note that ordinary Portland cement, a commercially available product with a Blaine value of 3,200 cm 2 / g and a specific gravity of 3.16 was used. For the fine aggregate, river sand from the Himekawa River system in Iwamizawa City, Niigata Prefecture, in surface-dry condition with a specific gravity of 2.62 and a maximum particle size of 5 mm was used. For the coarse aggregate, crushed stone 1505 from the Himekawa River system in Iwamizawa City, Niigata Prefecture, in surface-dry condition with a specific gravity of 2.67 and a maximum particle size of 15 mm was used. Tap water was used for water. Also, the concrete was adjusted using a forced biaxial mixer, and the mixed concrete was measured in accordance with JIS A1101.

[0051] <Measurement method> Concrete compressive strength: For the compressive strength at the age of 1 hour and 1 day, the sprayed concrete was sprayed into a wooden formwork with a length of 50 cm, a width of 50 cm, and a depth of 15 cm. After spraying into the wooden formwork according to the NEXCO test method 726, 12 pins were penetrated for each age, and the compressive strength was calculated from the penetration resistance of the pins. The compressive strength at the age of 28 days was obtained by spraying the quick-setting sprayed concrete into a formwork with a width of 50 cm, a length of 50 cm, and a thickness of 20 cm, and measuring the compressive strength of the specimens with a diameter of 5 cm and a length of 10 cm collected by a 20-ton pressure testing machine. Rebound rate: The quick-setting sprayed concrete was sprayed for 10 minutes at a pumping speed of 10 m 3 / h. Assuming water gushing, water was flowing from the upper part at a rate of 10 liters per minute for 10 minutes, and it was sprayed onto a simulated tunnel with a height of 3.5 m and a width of 2.5 m formed in an arch shape on an iron plate. Then, (rebound rate) = (the amount of quick-setting sprayed concrete that fell without adhering to the simulated tunnel + the amount of water gushing of 100 kg per 10 minutes) / (the amount of quick-setting sprayed concrete sprayed onto the simulated tunnel + the amount of water gushing of 100 kg per 10 minutes) × 100 (%). Dust amount: The quick-setting sprayed concrete was sprayed onto the simulated tunnel for 10 minutes at a pumping speed of 10 m 3 / h. Then, the dust amount was measured at a fixed position 5 m from the spraying location. Solidification amount: After the test, the Y-shaped confluence pipe of the concrete and the quick-setting agent was washed with water and dried, and then the solidification amount was measured. The measurement was calculated as solidification amount = the weight of the Y-shaped confluence pipe after use - the weight of the Y-shaped confluence pipe before use. Mixing property evaluation: The standard deviation was obtained from the 12 compressive strengths measured by the pin penetration resistance value in the compressive strength tests at the age of 1 hour and 1 day. The mixing property was evaluated from the standard deviation value. As a rough guide, those with a standard deviation exceeding 0.8 at 1 hour are judged to have large variations, and those exceeding 2.0 at 24 hours are judged to have large variations.

[0052]

Table 3

[0053] 「Experimental Example 2」 Mortar tests and concrete spraying tests were conducted with all materials, test methods, and addition amounts being the same as those in Experimental Example 1, except that a powder admixture consisting of 5 parts of an alkali carbonate of the type shown in Table 4, 60 parts of calcium aluminate (V), and 35 parts of calcium sulfate powder was used. The results are shown in Table 4.

[0054] (Alkali carbonate) ·Alkali carbonate B: Commercially available potassium carbonate (BET specific surface area 600 cm 2 / g) ·Alkali carbonate C: Commercially available sodium hydrogen carbonate (BET specific surface area 500 cm 2 / g) ·(Comparative) Alkaline earth carbonate: Commercially available calcium carbonate (BET specific surface area 600 cm 2 / g)

[0055]

Table 4

[0056] 「Experimental Example 3」 Mortar tests and concrete spraying tests were conducted with all materials, test methods, and addition amounts being the same as those in Experimental Example 1, except that a liquid accelerating agent of the type shown in Table 5 was used. The results are shown in Table 5.

[0057] (Liquid accelerating agent) ·Liquid accelerating agent β: A reagent-grade aluminum sulfate dissolved in pure water, adjusted to a concentration of 27%, and adjusted with sodium hydroxide so that the pH is 5.0 ·Liquid accelerating agent γ: A reagent-grade aluminum sulfate dissolved in pure water, adjusted to a concentration of 27%, and adjusted with sodium hydroxide so that the pH is 6.0

[0058]

Table 5

[0059] 「Experimental Example 4」 Mortar tests and concrete spraying tests were conducted in the same manner as in Experimental Example 1, using all the same materials, test methods, and addition amounts, except that calcium aluminate (v) and 5 parts of alkali carbonate A shown in Table 6 were used, and a powder admixture composed of calcium sulfate was used. The results are shown in Table 7. In addition, the amount of calcium sulfate was adjusted for the portion where the powder admixture did not reach 100 parts due to the addition of calcium aluminate (v).

[0060]

Table 6

[0061] 「Experimental Example 5」 Mortar tests and concrete spraying tests were conducted in the same manner as in Experimental Example 1, using all the same materials, test methods, and addition amounts, except that aluminum sulfate and a liquid accelerating agent with the remainder being pure water, shown in the percentages in Table 7, were used. The results are shown in Table 7.

[0062]

Table 7

[0063] 「Experimental Example 6」 Mortar tests and concrete spraying tests were conducted in the same manner as in Experimental Example 1, using all the same materials, test methods, and addition amounts, except that alkali carbonate A, 60 parts of calcium aluminate (v), and a powder admixture composed of calcium sulfate, shown in the percentages in Table 8, were used. The results are shown in Table 8. In addition, the amount of calcium sulfate was adjusted for the portion where the powder admixture did not reach 100 parts due to the addition of alkali carbonate A.

[0064]

Table 8

[0065] 「Experimental Example 7」 A powder admixture consisting of 5 parts of alkali carbonate A, 60 parts of calcium aluminate (V), and 35 parts of calcium sulfate, and a liquid quick-setting agent α were mixed with 100 parts of cement shown in Table 9. Mortar tests and concrete spraying tests were conducted in the same manner as in Experimental Example 1. The results are shown in Table 9.

[0066]

Table 9

Industrial Applicability

[0067] The present invention can be applied to locations where high quick-setting properties are required and long-term strength development is desired in spraying operations such as tunnels.

Claims

1. A foaming quick-setting agent used by mixing a powder admixture and a liquid quick-setting agent, The powder admixture has a SiO ２ calcium aluminate powder and an alkali carbonate powder, with a content of 7% by mass or less, a vitrification rate of 30 to 98% by mass, and a sulfur content of 0.007 to 0.5% by mass, and contains containing 20 parts by mass or more of the calcium aluminate powder in 100 parts by mass of the powder admixture, containing 0.1 part by mass or more of the alkali carbonate in 100 parts by mass of the powder admixture, wherein the liquid quick-setting agent contains 20 parts by mass or more of aluminum sulfate having a pH of 1 to 5 in 100 parts by mass of the liquid quick-setting agent.

2. The CaO / Al of the calcium aluminate powder ２ O ３ The foaming quick-setting agent according to claim 1, wherein the molar ratio is 1.8 to 2.

9.

3. In the calcium aluminate powder, 3CaO·Al ２ O ３ is contained in an amount of 1 to 40% by mass in the foaming quick-setting agent according to claim 1 or 2.

4. The foaming quick-setting agent according to any one of claims 1 to 3, wherein the alkali carbonate powder is sodium carbonate powder.

5. The foaming quick-setting agent according to any one of claims 1 to 4 is a spraying method added to the concrete immediately before the concrete is sprayed, wherein the powder admixture is added in an amount of 3 parts by mass or more per 100 parts by mass of cement in the concrete, and the liquid quick-setting agent is added in an amount of 4 parts by mass or more per 100 parts by mass of cement in the concrete.

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