JP7077146B2 - Quickly miscible material - Google Patents

Description

The present invention relates to a powdery admixture for imparting quick-setting property to a cement-based composition and sprayed concrete using the admixture.

In tunnels, mining pits, underground spaces, etc., sprayed concrete is constructed from the viewpoint of preventing the collapse of the excavated surface and reinforcing the ground during and after excavation. The sprayed concrete guarantees the adhesion to the construction object by its quick connection. The quick-setting component is mixed with concrete to give quick-setting property, but the powder quick-setting agent containing calcium aluminate, sodium aluminate, etc. as the active ingredient can give strong quick-setting property and is a liquid quick-setting agent. Compared to this, it is easy to obtain concrete with high strength. In the wet spraying method, which is a general construction method for sprayed concrete, for example, at least cement, water, and aggregate are weighed and mixed to prepare a base concrete, which is then sprayed at the time of construction via an agitator truck or the like. Pump pump to the device. In the spraying device, a separately sent powder or liquid quick-setting admixture is added to the base concrete being pumped, and mixing is promoted in the spraying nozzle of the spraying device to form the sprayed concrete, which is sprayed from the nozzle end hole. In the dry spraying method, which is another construction method, at least cement other than water and liquid, aggregate, and powder quick-setting admixture are weighed and mixed to prepare drymix concrete, which is then used in a storage tank or the like. Air pressure is sent to the spraying device at the time of construction. In the spraying device, water is added to the dry mix concrete being pumped, and mixing is advanced until it is pumped to the spray nozzle to form sprayed concrete, which is similarly sprayed. In either construction method, while the quick-connecting component in the spraying device moves from the point where the quick-connecting component comes into contact with water (water contact point) to the discharge hole at the end of the spray nozzle, mixing is performed to form sprayed concrete. The distance used for mixing is usually a distance of several tens of cm to several meters, and the traveling time is the mixing time. In general, the longer this distance is, the more the mixing progresses, the higher the mixing property, and the easier it is to obtain concrete that is more uniform in terms of structure and properties.

In order to obtain such sprayed concrete, the powdery quick-setting material to be mixed is generally composed of the above-mentioned quick-setting component to which an auxiliary agent for adjusting various properties is added. For example, calcium aluminate with a high CaO content as a chemical component is blended with sekkou that promotes curing, and sodium aluminate that enhances initial strength development and sodium carbonate that promotes coagulation are added to these to make them highly alkaline. In the typical powder quick-setting material (see, for example, Patent Documents 1 to 3), the primary purpose is to provide a high quick-setting property and an initial strength-developing action. For this reason, condensation occurs in a very short time after the quick-bonding material comes into contact with water. Therefore, when the mixing distance is lengthened, the concrete tends to solidify during that time, which may cause a serious spraying disorder such as clogging or blockage. On the other hand, if the mixing distance is shortened, there is a risk of insufficient mixing, and if the mixing state is non-uniform, fine unevenness is likely to occur in the reaction of the constituent components. Is difficult to obtain, and the curability such as strength is also inferior. Further, when a setting delay component such as hydroxy acids is used in combination (for example, see Patent Document 4), the fluidity of the concrete can be maintained even for a relatively long time, so that the mixing time can be lengthened, but the quick setting and the initial strength can be extended. Curability such as expression is reduced.

Japanese Unexamined Patent Publication No. 2012-121763 Japanese Patent Application Laid-Open No. 2003-012356 Japanese Patent No. 5129955 Japanese Unexamined Patent Publication No. 2001-354464

Therefore, the present invention is a powdery quick-setting admixture that can be handled without restrictions for obtaining sprayed concrete that can easily provide higher mixability without impairing the curability while having high adhesiveness. An object of the present invention is to provide a sprayed concrete having the above-mentioned properties, which is a mixture thereof.
More specifically, without lowering the strength development, even if it comes into contact with water, it hardly promotes coagulation for a very short time, but from the end of the time, it causes substantially instantaneous coagulation, and thus has high miscibility. It is suitable for obtaining high miscibility because it can provide a powdery quick miscible admixture that can easily provide adhesiveness to concrete or the like and can prolong the kneading time without impairing the curability. Another object is to provide sprayed concrete having high adhesiveness.

As a result of various studies for solving the above-mentioned problems, the present inventor has made a sulfate of an alkali metal in an admixture containing calcium aluminate as a main quick-setting component and a sulfate of an alkali metal, an alkaline earth metal and aluminum. In addition to containing a specific amount of sulfate and aluminum sulfate, at least the content of alkaline earth metal sulfate and aluminum sulfate has a specific correlation to ensure a fluid state suitable for mixing. The present invention has been completed because it has been found that the time can be adjusted and that after the lapse of time, a sprayed concrete in which condensation progresses rapidly can be obtained without a decrease in strength development.
That is, the present invention is the following quick-setting admixtures [1] to [2] and the sprayed concrete of [3] to [4].

[1] Calcium aluminate having a molar ratio (CaO / Al ₂ O ₃ ) of CaO and Al ₂ O ₃ as chemical components of 1.8 to 2.5 is 62 to 86.2% by mass, and the balance is alkaline. A powdery quick-knot admixture containing each sulfate of metal, alkaline earth metal and aluminum, and the sulfate of the alkali metal (S1) in terms of anhydride with respect to 100 parts by mass of the calcium aluminate content. ) Is 5 to 16 parts by mass, the content of the aluminum sulfate (S3) is 1 to 10 parts by mass, and the alkaline earth metal sulfate (S2) and the aluminum sulfate (S3). A fast-knot admixture, characterized in that the content mass ratio of aluminum is 1 ≦ (S2 / S3) ≦ 35 in terms of alkali.
[2] The quick-setting miscible material according to [1], which further contains an alkali metal carbonate in the balance.
[3] Sprayed concrete containing cement, aggregate, and the quick-setting admixture according to the above [1] or [2] in an amount corresponding to 5 to 15% by mass of the cement content in terms of anhydrate.
[4] The sprayed concrete according to the above [3], further containing a water reducing agent and / or a thickener.

According to the present invention, the following main effects (1) to (5) are exhibited.
(1) It is possible to spray concrete with higher mixing property by normal spraying work.
(2) Since it is possible to obtain sprayed concrete having high quick-setting property without reducing the quick-setting property, the adhesiveness is excellent.
(3) Sprayed concrete having stable strength development can be obtained from the initial stage to the medium to long term without stagnation.
(4) Sprayed concrete with uniform properties and quality can be obtained.
(5) Since the alkali content is low, the risk of damage to the human body and the surrounding environment is reduced.

The quick-setting admixture of the present invention contains calcium aluminate as a main quick-setting component, and is in the form of a powder containing at least an alkali metal sulfate, an alkaline earth metal sulfate, and an aluminum sulfate. It is a quick-setting admixture. Calcium aluminate used in this quick-setting admixture is an inorganic hydration active substance containing CaO and Al ₂ O ₃ as the main chemical components, and the raw material that is the source of CaO and the raw material that is the source of Al ₂ O ₃ are used. A raw material mixture blended so as to obtain a heated product (clinker) having a molar ratio (CaO / Al ₂ O ₃ ) of Ca O and Al ₂ O ₃ as chemical components of 1.8 to 2.5 is preferably used. It is obtained by heating until it melts. The preferred molar ratio (CaO / Al ₂ O ₃ ) is 2.0-2.4. If the molar ratio of CaO / Al _{2O 3} ) is less than 1.8, it is not preferable because the quick-setting property is low and it is difficult to obtain high initial strength. If the molar ratio (CaO / Al ₂ O ₃ ) exceeds 2.5, strong instantaneous binding tends to occur and workability deteriorates, which is not preferable. In addition, the calcium aluminate used in this quick-setting admixture also contains different components such as impurities other than CaO and Al ₂ O ₃ derived from the raw materials, such as when a natural mineral raw material is used as the raw material for the production. Regardless of its existence form, it can be included within a range that does not impair the effects of the present invention.

In addition, since various differences occur in the structural state of calcium aluminate after cooling due to differences in the cooling process after heating during manufacturing, glass is the degree of amorphization depending on the cooling conditions, for example, the cooling rate. The conversion rate can be adjusted. In general, the higher the vitrification rate, the higher the reaction activity. Therefore, the calcium aluminate used in this quick-setting admixture is not limited, but is substantially more vitrified than the crystalline calcium aluminate. However, it is better to use calcium aluminate. Preferably, calcium aluminate having a vitrification rate of 60% or more is used. Most preferably, it is calcium aluminate having a vitrification rate of about 95% or more. The degree of powderiness of calcium aluminate is not particularly limited. Preferably, the powderiness is equal to or higher than that of the cement in the hydraulic composition to be mixed because it is easy to obtain an appropriate reaction activity when used as a quick-mixing material for concrete. More preferably, it has a specific surface area of 3000 to 6500 cm and a powderiness of ² / g.

The quick-setting admixture of the present invention contains 62 to 86.2% by mass of such calcium aluminate. If the calcium aluminate content in the quick-setting admixture is less than 62% by mass, the quick-setting property is insufficient and the adhesiveness when mixed with the sprayed concrete is poor, which is not preferable. On the other hand, if it exceeds 86.2% by mass, the strength development may be lowered and the curability may be lowered, which is not preferable. The calcium aluminate content in the quick-setting admixture is preferably 64 to 85% by mass, more preferably 65 to 82% by mass, still more preferably 65 to 81% by mass.

Further, as the sulfate of the alkali metal contained in the quick-setting admixture of the present invention, any sulfate of at least any one of lithium, potassium and sodium can be used. Preferably, an anhydride having a high reaction activity is used. More preferably, anhydrous sodium sulfate is used in consideration of economic efficiency. Alkali metal sulfate contributes to the promotion of condensation. The content of the alkali metal sulfate in the quick-setting admixture is 5 to 16 parts by mass with respect to 100 parts by mass of the calcium aluminate content. If the content is less than 5 parts by mass, it is difficult to develop high initial strength, which is not preferable. Further, if the content exceeds 16 parts by mass, the expression of long-term strength is low, which is not preferable. The preferable content of the alkali metal sulfate in the quick-setting admixture is 5 to 15 parts by mass, more preferably 5 to 14 parts by mass, and further preferably 6 with respect to 100 parts by mass of the calcium aluminate content. ~ 14 parts by mass.

Further, the aluminum sulfate contained in the quick-setting admixture of the present invention may be any aluminum sulfate, and for example, either a hexahydrate or an anhydrate can be used. The use of aluminum sulfate hexahydrate is recommended because of its high property stability. The content of aluminum sulfate contributes to imparting quick-setting property as a quick-setting aid, and particularly exerts an action of promoting the setting start time. The content of the sulfate of aluminum is 1 to 10 parts by mass in terms of anhydrate with respect to 100 parts by mass of the calcium aluminate content. If it is less than 1 part by mass, the adhesiveness when used for sprayed concrete is lowered, and if the content is more than 10 parts by mass, the tendency of instant formation becomes stronger, which may hinder the mixing property at the time of construction, which is not preferable. The preferable content of the aluminum sulfate in the quick-setting admixture is 1 to 9 parts by mass, more preferably 1 to 8 parts by mass, and further preferably 2 with respect to 100 parts by mass of the calcium aluminate content. ~ 8 parts by mass.

Further, in the quick-setting admixture of the present invention, the mass ratio (S2 / S3) of the sulfate of alkaline earth metal (S2) and the sulfate of aluminum (S3) in terms of anhydride is 1 ≦ (S2). / S3) It is contained so as to satisfy the relationship of ≦ 35. By containing the sulfate of alkaline earth metal and the sulfate of aluminum satisfying the above relationship, for example, in a cement-based water-hard composition, for a very short time from the contact with the quick-setting admixture. It exhibits fluidity, then rapidly condenses, and strength development is also improved. If the mass ratio (S2 / S3) is less than 1, the time during which the fluidity can be maintained becomes shorter, and the mixing time tends to be insufficient, making it difficult to obtain a uniform work piece, which is not preferable, and the mass ratio (S2). If / S3) exceeds 35, the setting becomes slow and the adhesiveness is lowered, which is not preferable. The preferred mass ratio (S2 / S3) is 1 ≦ (S2 / S3) ≦ 25, more preferably 1 ≦ (S2 / S3) ≦ 20, and even more preferably 1 ≦ (S2 / S3) ≦ 15. be.

The sulfate of the alkaline earth metal used may be any sulfate of an alkaline earth metal such as magnesium or calcium. Preferably, anhydrous gypsum (anhydrous calcium sulfate) is used because it can have relatively high reaction activity and strength development. The particle size and particle size of the sulfate of the alkaline earth metal used is not limited, but in consideration of storage stability, a brain specific surface area of about 4000 to 6500 cm ² / g is preferable. It is necessary that the content of the alkaline earth metal sulfate (in terms of anhydrate) in the quick-bonding admixture is an amount that satisfies the correlation with the content of the sulfate of aluminum. Preferably, in addition to satisfying this relationship, the total content of aluminum with sulfate exceeds the alkali metal content in the quick-setting admixture to ensure high strength development. However, it is good because the onset of rapid onset is quick ((S1) <(S2 + S3)). More preferably, in addition to satisfying the above conditions, the content of the sulfate of the alkaline earth metal is 10 to 35 parts by mass with respect to 100 parts by mass of the calcium aluminate content. More preferably, the content of the sulfate of the alkaline earth metal is 15 to 35 parts by mass with respect to 100 parts by mass.

The quick-setting admixture of the present invention may contain components other than the above as long as the effects of the present invention are not impaired. Specifically, it is preferable to contain an alkali metal carbonate. Examples of the carbonate of the alkali metal include lithium carbonate, potassium carbonate and sodium carbonate, and it is desirable to use an anhydride for each of them, and two or more kinds may be used in combination. Curing-promoting action can be imparted by the carbonate of alkali metal. When the alkali metal carbonate is contained, the preferable content is 2 to 10 parts by mass, more preferably 2 to 9 parts by mass, and further preferably 2 to 8 parts with respect to 100 parts by mass of the calcium aluminate content. It is a mass part. Further, the particle size of the quick-setting admixture of the present invention is not particularly limited, and may be powder or granular. Desirably, a powder having a specific surface area of 3000 to 6500 cm ² / g and a maximum particle size of 1 mm or less can be obtained because good reaction activity can be obtained without being easily weathered.

Further, the sprayed concrete of the present invention is at least a sprayed concrete containing the above-mentioned quick-setting admixture, cement and aggregate. Even if it is a mixture consisting of at least the quick-knot admixture, cement and aggregate before adding the kneading water, the mixture containing the miscible material other than the quick-knot admixture and the cement and aggregate is added with the kneading water. , Any of which is added with a quick-setting admixture later.

The cement used for the sprayed concrete of the present invention is preferably Portland cement, and any type of Portland cement may be used. Specific examples thereof include various Portland cements of ordinary, early-strength, ultra-fast-strength, moderate heat, low heat, and sulfate resistant. In addition, mixed cements such as blast furnace cement and fly ash cement containing Portland cement can also be used. More preferably, ordinary Portland cement is used from the viewpoint of economy and versatility. When Portland cement is used, the particle size is not particularly limited as long as it meets the JIS standard (JIS R 5210) 2500 cm ² / g or more. 3400 cm ² / g) can be used.

The aggregate used for the sprayed concrete is specifically composed of a fine aggregate and a coarse aggregate. The fine aggregate is not particularly limited as long as it can be used for mortar or concrete. Further, the coarse aggregate is not particularly limited as long as it can be used for concrete. Preferably, both the fine aggregate and the coarse aggregate have a surface dry density of 2.3 to 2 because it is easy to secure a predetermined aggregate strength and the difference in specific gravity from other contained components is small, so that material separation is unlikely to occur. 0.9 g / cm ³ aggregate is used. Specific examples of such aggregates include natural aggregates such as silica sand and limestone sand, and crushed sand such as andesite, sandstone, and basalt in the case of fine aggregates. In addition, examples of coarse aggregate include crushed stones and gravel such as silica stone, limestone, andesite, sandstone, and basalt. The content of aggregate in the sprayed concrete is not particularly limited, but the total of coarse aggregate and fine aggregate is 300 to 570 parts by mass and the ratio of fine aggregate is 100 parts by mass with respect to 100 parts by mass of Portland cement. (Mass ratio of fine aggregate in total aggregate) is preferably 54 to 69%.

The sprayed concrete of the present invention preferably further contains a water reducing agent and / or a thickening agent. Among these, the water reducing agents correspond to those called water reducing agents, dispersants, high-performance water reducing agents, high-performance AE water reducing agents, AE water reducing agents, fluidizing agents and the like that can be used for mortar and concrete. The active ingredient thereof is also not particularly limited, and examples thereof include naphthalene sulfonic acid formalin condensate, lignin sulfonic acid formalin condensate, melamine sulfonic acid, and polycarboxylic acid. By containing the water reducing agents, it is possible to impart appropriate fluidity to the base concrete without increasing the amount of kneaded water that leads to a decrease in strength. The content of water reducing agents per 100 parts by mass of Portland cement is preferably 0.3 to 1.6 parts by mass in terms of solid content.

The thickener used for the sprayed concrete of the present invention is not particularly limited as long as it is a thickener that can be used for mortar and concrete. Preferably, a thickener containing a water-soluble cellulose derivative as an active ingredient can be used. By containing a thickener, it is possible to suppress the generation of dust during spraying. The content of the thickener per 100 parts by mass of the cement content in the sprayed concrete is preferably 0.05 to 0.15 parts by mass.

Further, the sprayed concrete of the present invention may contain components other than the above as long as the effects of the present invention are not impaired. Examples of the components that can be contained include short fibers that can be used for mortar and concrete, pozzolan-reactive substances, and the like, but the components are not limited to the described examples.

In the sprayed concrete of the present invention, it is desirable to add (inject) kneaded water at the time of producing the base concrete in which the compounding components other than the quick-setting admixture are mixed in advance. To prepare the base concrete, a commercially available concrete mixer or the like is used, and at least Portland cement, aggregate, etc. excluding the quick-setting admixture are put into the mixer in a predetermined amount, and then water is poured and kneaded. The amount of water is not particularly limited, and may be any amount as long as it can react with components having hydration reaction activity such as cement and anhydrous gypsum in almost no excess or deficiency. An example of a specific guideline for the amount of water is approximately 52 to 68 parts by mass with respect to 100 parts by mass of cement in concrete, but the amount is not limited. A more preferable blending amount of water is 55 to 65 parts by mass in order to enhance the miscibility at the time of water injection and enhance the mortar strength development.

As the spraying method using the sprayed concrete of the present invention, the above-mentioned wet spraying method or the dry spraying method may be used, but it is more preferable to adopt the wet spraying method.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the described Examples. Unless otherwise specified, the examples were carried out in an environment of 20 ± 1 ° C.

[Preparation of calcium aluminate]
Using commercially available industrial chemicals CaCO ₃ and Al ₂ O ₃ , weighed and blended so that calcium aluminate whose molar ratio of Ca O and Al ₂ O ₃ (CaO / Al ₂ O ₃ ) is shown below can be obtained. Then, a raw material formulation was prepared with a Henshell type mixer. This raw material formulation was heated in an electric furnace at about 1600 ° C. ± 50 ° C. for 60 minutes. Except for some, the heated material was immediately taken out of the furnace after the heating time had elapsed. Nitrogen gas for cooling was sprayed on the surface of the heated product taken out at a maximum flow rate of about 30 mL / sec to quench it, and a cooled product was obtained. The vitrification rate of the cooled material was adjusted by spraying the nitrogen gas at a flow rate lower than the maximum value. In addition to a substantially amorphous calcium aluminate coolant having a vitrification rate of more than approximately 99% obtained by spraying a cooling gas at a maximum flow velocity, a vitrification rate of about 95% and a vitrification rate of about 60%. A calcium-aluminate coolant was also made. Each cooled product was crushed with an all-steel ball mill and sized to a brain specific surface area of about 5400 cm ² / g by a classification device. As the sized powder, the vitrification rate (the vitrification rate is abbreviated as G in Table 1) exceeds 99%, and the molar ratio of CaO and Al ₂ O ₃ (CaO / Al ₂ O ₃ ) is 1. Calcium aluminate powder of 0.8, 2.0, 2.3, 2.5 and 3.0 (in Table 1, the molar ratio of CaO and Al _{2O 3} is abbreviated as C / A ratio). Calcium aluminate powder with a vitrification rate of about 95% and a molar ratio of CaO and Al _{2O 3} (CaO / Al _{2O 3} ) of 2.0 and CaO and Al _2O with a vitrification rate of about 60%. A calcium aluminate powder having a molar ratio of ₃ (CaO / Al ₂ O ₃ ) of 2.3 was obtained. Since the obtained calcium aluminate powder is a water-free powder that does not absorb moisture, it was stored in a sealed container until the compound was used. The vitrification rate of calcium aluminate is the sum of the contained mineral phases that can be quantified by quantifying the mass of each mineral contained in the calcium aluminate clinica having a mass of M1 by an internal standard method or the like using a powder X-ray diffractometer. Mass; M2 was calculated, the balance was regarded as a pure glass phase, and the vitrification rate was calculated by the following formula.

(Number 1)
Vitrification rate (%) = (1-M2 / M1) x 100

[Making a quick-setting admixture]
Using the 7 kinds of calcium aluminates prepared above, a quick-setting miscible material was prepared according to the blending amount shown in Table 1. In addition, anhydrous sodium sulfate, anhydrous lithium sulfate, anhydrous gypsum, aluminum sulfate hexahydrate, sodium carbonate and sodium aluminate used for compounding are all commercially available reagents, and the compounding amount shown in Table 1 is based on the anhydride equivalent value. It is a mass part. In the preparation of the quick-setting admixture, the compounding materials in Table 1 were dry-mixed with a Henschel mixer for about 1 minute.
In addition to the quick-setting admixture described as "reference product" in Table 1, A1, A3, A6, A7, A8, A10, A11, A12 and A22 described as "the product of the present invention" are also included. It is a "reference product".

[Making base concrete]
Ordinary Portland cement (commercially available; brain specific surface area 3200 cm ² / g, density 3.15 g / cm ³ ) as cement, limestone fine aggregate as fine aggregate (surface dry density; 2.65 g / cm ³ , center particle size; 0.6 mm), as a coarse aggregate, crushed stone from Sakuragawa Tomiya, Ibaraki Prefecture (surface dry density; 2.74 g / cm ³ , particle size 5 to 15 mm), as a high-performance water-reducing agent, a polycarboxylic acid-based high-performance water-reducing agent (concentration) Table 2 shows the materials and kneaded water selected from 23% liquid, commercial products, the blending amounts shown in Tables 2 and 4 are solid content equivalents) and thickeners (water-soluble commercial products containing propylmethyl cellulose as an active ingredient). It was put into a concrete mixer all at once so as to have the blending amount shown in. Wet mixing was performed with this mixer for about 2 minutes to prepare 1.5 m ³ of each base concrete.

[Making sprayed concrete]
The quick-setting admixture was added to the base concrete to be prepared so as to have the addition amount shown in Table 3 in terms of anhydrate, and sprayed concrete was prepared by the following procedure.
In addition to the sprayed concrete described as "reference product" in Table 3, C1, C3, C6, C7, C8, C10, C11, C12, C22 and C32 described as "invention product" are also included. It is a "reference product".

In the procedure for producing the sprayed concrete, the base concrete was immediately put into a supply tank after kneading, and pumped from there to the spraying device via a resin hose having a length of about 10 m and an inner diameter of 6 cm. The spraying device is a cylindrical side for supplying and adding an additive (rapid admixture) to the pressure feed pipe with an inner diameter of 2 inches to which the base concrete is pumped and the base concrete that communicates with the side surface at an inclination angle of about 30 degrees. It is a commercially available product whose basic configuration is a pipe and an injection nozzle having an inner diameter (tip hole diameter) of 2 inches for spraying sprayed concrete. Here, the side pipe for supplying the additive was formed by inserting a steel T-shaped pipe (three-way pipe) between the main pipe for pumping and the nozzle for injection. That is, the pressure feed pipe main pipe and the injection nozzle are connected to the two pipe openings located on the straight line of the T-shaped pipe, and the supply pipe of the quick-connect admixture material to be separately sent is connected to the remaining pipe openings. The structure was made. During the distance from the position where the quick-setting admixture is added to the base concrete in the T-shaped pipe (the confluence of the base concrete and the quick-setting admixture) to the end of the injection nozzle hole, the base concrete and the quick-setting admixture The mixture was made, and the distance (hereinafter referred to as the mixing distance) was set to roughly 1.5 m or 5 m. The quick-setting admixture is pneumatically pumped in a predetermined amount by compressed air, added to the base concrete being pumped in the spraying device, and the added concrete is mixed while traveling a predetermined mixing distance, and the sprayed concrete is produced. Obtained.

[Evaluation of urgency]
In the formulation of the base concrete in Table 2, the amount corresponding to the total content of the coarse aggregate and the fine aggregate contained in each is set to the content of the fine aggregate, and the coarse aggregate is not contained, and other components and their components are used. The content was left unchanged in Table 2, and the base mortar changed to the mortar composition was also prepared by the same procedure as the base concrete. The composition of the base mortar is shown in Table 4.

The amount of the quick-setting admixture added to the obtained base mortar with respect to 100 parts by mass of Portland cement in the base mortar corresponds to the amount of quick-setting admixture per 100 parts by mass of Portland cement in the base concrete shown in Table 3. The amount was added so as to be the same as the amount of the material added, and the mixture was mixed with a high-speed mixer for 5 seconds to prepare a mortar kneaded product. The specific amount added to the base mortar is shown in Table 5. In addition to REIT, sprayed concrete was prepared by the following procedure.
In addition to the mortar kneaded product described as "reference product" in Table 5, C1M, C3M, C6M, C7M, C8M, C10M, C11M, C12M, C22M and C32M described as "invention product". Is also a "reference product".

The proctor penetration resistance value of the mortar kneaded product 20 seconds, 40 seconds, 60 seconds, and 180 seconds after the addition of the quick-setting admixture was measured to evaluate the quick-setting property. The measurement method of Procter penetration resistance is based on the concrete standard specification of the Japan Society of Civil Engineers "Quality standard for quick-setting admixture for sprayed concrete" and Annex "Measuring method of quick-setting time by penetration resistance of mortar with quick-setting admixture". A 0.125 cm ² Procter needle was used. The measurement results of this penetration resistance value are also shown in Table 6. Here, "x" described in the table indicates that the hardening of the mortar has progressed and the penetration resistance cannot be measured. In addition, the description "> 16 (N / mm ² )" was able to drive the Proctor needle, but exceeded the measurement limit (maximum 16 N / mm ² ) of the equipment used this time.
In addition to the mortar kneaded product described as "reference product" in Table 6, C1M, C3M, C6M, C7M, C8M, C10M, C11M, C12M, C22M and C32M described as "invention product". Is also a "reference product".

[Evaluation of adhesiveness of sprayed concrete]
Using the spraying device described above, the obtained sprayed concrete was immediately subjected to spraying work. The spraying work was sprayed on the following objects. That is, the sprayed concrete was sprayed at a flow rate of 10 m ³ / hour toward a concrete flat plate surface of 9 mm in thickness and 3 m square, which was installed vertically at a point about 100 cm away from the nozzle hole end of the spraying device. The adhesiveness of the sprayed concrete was evaluated by visual observation as follows. That is, the concrete sprayed on the flat plate surface did not drip or peel off, and the one that continued to adhere was judged to have "good" adhesion, and the concrete that was in any other state or sprayed itself could not be substantially performed. All of them were judged to have "poor" adhesion. The results are shown in Table 7.

Further, after performing such spraying for 5 minutes for each of the mixing distances (1.5 m or 5 m), the pumping supply of the base concrete is stopped for 30 minutes, the spraying is interrupted, and then the pumping supply of the base concrete is restarted. And sprayed again. At that time, if there is a pumping obstacle such as stenosis or blockage in the pumping path of the distilling head or spraying device, or a spraying obstacle such as a decrease in the amount of sprayed concrete, it is judged as "poor". did. In addition, those in which these phenomena were not observed, the pumping could be performed smoothly, and the spraying amount did not fluctuate were judged to be "good" in pumping performance. This result is also shown in Table 7. The mixing time when the mixing distance sprayed at the flow rate was 1.5 m was about 1.0 second, and similarly, the mixing time when the mixing distance was 5 m was about 3.5 seconds.
In addition to the sprayed concrete described as "reference product" in Table 7, C1, C3, C6, C7, C8, C10, C11, C12, C22 and C32 described as "invention product" are also included. It is a "reference product".

[Evaluation of strength development of sprayed concrete]
The mixing distance was set to 1.5 m, and the sprayed concrete prepared as described above was immediately sprayed into a forming form having an inner size of 30 × 40 × 20 cm to fill the inside of the formwork. This was placed in a constant temperature chamber at 20 ° C (± 1 ° C), and after a predetermined time had passed, a columnar specimen with a diameter of 5 cm and a height of 10 cm was collected from the hardened concrete in the formwork with a core drill, and the specimen was aged 28 days. Got The uniaxial compressive strength of this 28-day-old specimen was measured with an Amsler-type compressive strength tester. Further, the sprayed concrete prepared in the same manner as described above was subjected to the pullout test compliant with JSCE-G561 by using the formwork and the embedding tool for the pullout test specified in the JSCE standard JSCE-G561. The compressive strength of the sprayed concrete for 4 hours and 1 day was measured by the test. Table 7 shows the results of strength measurement of each specimen. In addition, since the strength measurement test is not possible for the uncured material at a predetermined age, the measurement value column in Table 7 is indicated by "x". Also, for a part of the sprayed concrete produced by the same procedure as above with the mixing distance set to 5 m, the material age is 4 hours, 1 day and 28 days by the same method as when the mixing distance is set to 1.5 m. The compressive strength of the sprayed concrete was measured. The results are shown in Table 8.
In addition to the sprayed concrete described as "reference product" in Table 8, C1 , C3 and C8 described as "product of the present invention" are also "reference products".

From the results shown in Table 7, the sprayed concrete of the present invention has a rapid connection property for ensuring sufficient adhesion during spraying work, high strength development is obtained from the initial stage, and strength growth is also good. I understand. On the other hand, the fluidity of concrete suitable for smooth pumping can be ensured before and after the addition of the quick-setting admixture, and even if the mixing distance is lengthened, the pumping failure is unlikely to occur, so that a sufficiently uniform mixed state can be obtained. In addition, when the results shown in Table 6 are combined, it can be seen that after a certain period of time, rapid condensation close to instantaneous condensation is observed, and therefore, even if the mixed state is enhanced, the adhesiveness at the time of spraying is very excellent. Furthermore, from the results in Table 8, the compressive strength value when the mixing distance is 5 m is often slightly improved as compared with the case of 1.5 m because the mixing property is improved. It can be seen that the sprayed concrete of the present invention can be sufficiently applied to a long mixing distance and time.

Claims (4)

Calcium aluminate having a molar ratio of CaO and Al ₂ O ₃ as a chemical component (CaO / Al ₂ O ₃ ) of 1.8 to 2.5 and a vitrification rate of 95% or more is 64 to 86. It is a powdery quick-setting admixture containing 2% by mass and each sulfate of alkali metal, alkaline earth metal and aluminum in the balance, and is converted into an anhydride with respect to 100 parts by mass of the calcium aluminate content. The content of the alkali metal sulfate (S1) is 6 to 14 parts by mass, the content of the aluminum sulfate (S3) is 1 to 4 parts by mass, and the content of the alkaline earth metal sulfate (S2). A fast-knot admixture characterized in that the content mass ratio of the aluminum sulfate (S3) is 1 ≦ (S2 / S3) ≦ 25 in terms of anhydride. The quick-setting miscible material according to claim 1, further containing an alkali metal carbonate in the balance. A sprayed concrete containing cement, an aggregate, and the quick-setting admixture according to claim 1 or 2, in an amount corresponding to 5 to 15% by mass of the cement content in terms of anhydrate. The sprayed concrete according to claim 3, further comprising a water reducing agent and / or a thickening agent.