JP2004123535A - Method for mixing quick setting spray cement concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for mixing and preparing quick-setting spray concrete of high strength and free of degradation in long-term strength by using a quick setting material with which high strength development can be anticipated in construction of a large cross section tunnel. <P>SOLUTION: The method for mixing the quick setting spray cement concrete comprises mixing the quick setting material containing 40 to 60wt% calcium aluminates, 60 to 40wt% sulfate, and powdery alkali metal aluminate of ≤10 pts. wt. per 100 pts. wt. in total of the calcium aluminates and the sulfate and the cement concrete prepared by mixing cement and water. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a quick-setting material used when spraying on an exposed ground surface in a tunnel such as a road, a railway, and a headrace, a quick-setting sprayable cement concrete using the quick-setting material, and a method of mixing the same. .

Conventionally, in order to prevent collapse of an exposed ground such as tunnel excavation, a method of spraying quick-setting spray concrete in which a quick-setting material is mixed with concrete has been performed (Patent Document 1).

In this spraying method, usually, a mixing and mixing plant installed at the excavation work site mixes cement, aggregate, and water to prepare sprayed concrete, transports it with an agitator truck, pumps it with a concrete pump, and in the middle of it This is a construction method in which the combined pipe is mixed with the quick-setting material fed from the other side and sprayed as a quick-setting sprayable concrete on the ground surface to a predetermined thickness. As a quick-setting material used in this spraying method, a mixture of calcium aluminate, alkali metal aluminate, alkali metal carbonate and the like has been used.

This quick-setting shotcrete quickly sets and cures quickly, so it can protect the ground surface where there is a risk of collapse. There is a problem that it is reduced by about 30% as compared with.

As described above, although the strength is reduced by the addition of the quick-setting material, the strength is sufficient to protect the ground in a relatively stable ground, and the spraying thickness in a considerably unstable ground. Has been dealt with by making it thicker.
Japanese Patent Publication No. 60-4149

However, increasing the spraying thickness is not economically preferable because the amount of the spraying material to be used increases, and there is a problem that the working time becomes longer.

In recent years, in the construction of large section tunnels, the exposed area of the ground has become large and the amount of spraying material used has become large, so a quick setting material that can be expected to have higher strength and a spraying material using it As the demand for concrete is increasing, there is a need for a high-strength quick-setting shotcrete that does not decrease in long-term strength.

As a result of intensive studies, the present inventor has obtained knowledge that can solve the above-mentioned problem by spraying using a specific quick-setting material, and has completed the present invention.

That is, the present invention relates to a calcium aluminate of 40 to 60% by weight, a sulfate of 60 to 40% by weight, and an alkali metal aluminate of less than 10 parts by weight with respect to a total of 100 parts by weight of calcium aluminate and sulfate. Is a quick-setting material. And, it is a quick-setting sprayable cement concrete characterized by containing the cement and the quick-setting material, further selected from the group consisting of a water reducing agent, a thickener, an ultrafine powder, and a fibrous substance. The quick-setting sprayed cement concrete comprises one or more admixtures.

こ と By using the quick-setting material of the present invention, it is possible to obtain a spray material whose strength after 28 days of age hardly decreases, and to increase the strength. Therefore, it is most suitable as a spraying material for unstable ground, and it is economical because the spraying thickness can be reduced.

Hereinafter, the present invention will be described in detail. In the present invention, paste, mortar, and concrete are collectively referred to as cement concrete.
As the cement used in the present invention, various portland cements such as ordinary, early-strength, moderate heat, and ultra-high-strength, which are generally commercially available, and various mixtures obtained by mixing fly ash, blast furnace slag, etc. with these portland cements Cement and the like may be mentioned, and these may be used after pulverized. Cement suitable for performance such as reduction of rebound rate and dust amount required for spraying, pumpability, strength development, construction conditions etc. can be selected, but generally available ordinary Portland cement and early strength Portland cement are available. preferable.

Also, a fluorocement containing fluorocalcium aluminate can be used. Furthermore, the CaO C, the Al ₂ O ₃ A, the SiO ₂ S, and when the Fe ₂ O ₃ and _{F, C 2 S, C 3} S, C 3 A, and C ₄ in the cement, shown as AF A special cement in which sulfates such as calcium sulfate, potassium sulfate, and sodium sulfate are used in combination with clinker fired while changing the content of the mineral composition can also be used.

The calcium aluminate used in the present invention is obtained by mixing a raw material containing calcia and a raw material containing alumina, and baking the mixture in a kiln. Obtained by heat treatment such as melting in an electric furnace, the CaO and Al ₂ O ₃ as a main component, means "calcium aluminate" having a hydration activity.

Among calcium aluminates, amorphous calcium aluminate is preferable from the viewpoint of reaction activity, and amorphous calcium aluminate obtained by quenching a heat-treated product corresponding to 12CaO · 7Al ₂ O ₃ (C ₁₂ A ₇ ) composition Aluminates are more preferred.

The particle size of calcium aluminates is preferably not less than 5000 cm ² / g in Blaine value. If it is less than 5000 cm ² / g, the quick setting property and the initial strength expression property may be reduced.

The use amount of calcium aluminates is preferably 40 to 60% by weight, more preferably 45 to 55% by weight, of the total of 100% by weight of calcium aluminates and sulfate. If it is less than 40% by weight, the initial setting is delayed, and the adhesion to the ground is reduced. If it exceeds 60% by weight, the long-term strength development may be reduced.

硫酸 The sulfate used in the present invention is used to improve strength development. Examples of the sulfate include alkali metal sulfates such as sodium sulfate and potassium sulfate, alkaline earth metal sulfates such as magnesium sulfate and gypsum, and aluminum sulfate, and one or more of these are used. Is also good. Among them, gypsum is preferred in terms of strength development.

硫酸 The sulfate used in the present invention is used to improve strength development. Examples of the gypsum include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum, and one or more of these may be used. Among these, anhydrous gypsum is preferred in terms of strength development.

The particle size of the gypsum, in terms of strength development, preferably 2500 cm ² / g or more in Blaine value, 5000 cm ² / g or more is more preferable. If it is less than 2500 cm ² / g, the strength expression may be reduced.

The amount of the sulfate used is preferably 60 to 40% by weight, more preferably 55 to 45% by weight, based on the total of 100% by weight of the calcium aluminates and the sulfate. If it is less than 40% by weight, the long-term strength development is small, and if it exceeds 60% by weight, the initial setting is delayed, and the adhesion to the ground may be reduced.

The alkali metal aluminate (hereinafter referred to as aluminate) used in the present invention promotes the initial setting of cement. For example, aluminum hydroxide and an alkali metal hydroxide are mixed and dissolved, and dried to form a powder. It is obtained.

Examples of the aluminate include sodium aluminate, potassium aluminate, lithium aluminate, and the like, and one or more of these may be used. Among these, sodium aluminate is preferred in terms of coagulability.

The 90% particle diameter of the aluminate is preferably 0.3 mm or less, more preferably 0.05 to 0.2 mm. If it is less than 0.05 mm, it may absorb moisture and the storage stability may be reduced, and if it exceeds 0.3 mm, the quick setting property may be reduced.

Depending on the production conditions, these aluminates can be prepared as anhydrides or those having water of crystallization, and any of them can be used.However, in view of improving storage stability when mixed with calcium aluminates, anhydrous aluminates are used. Are preferred.

Especially, from the viewpoint of improving the storage stability when mixed with calcium aluminates, the loss on ignition of the aluminate is preferably 10% by weight or less, more preferably 5% by weight or less. If the content exceeds 10% by weight, the storage stability is reduced when mixed with calcium aluminates, and the quality may be reduced. In addition, the ignition loss is obtained by heating the aluminate in an electric furnace at 1000 ° C. for 24 hours, and calculating from [1- (weight after heating) / (weight before heating)] × 100 (% by weight). Refers to the calculated value.

The amount of the aluminate used is less than 10 parts by weight, preferably 2 to 6 parts by weight, based on 100 parts by weight of the total of the calcium aluminate and the sulfate. If the amount is more than 10 parts by weight, the long-term strength development may be reduced.

急 The quick-setting material of the present invention contains calcium aluminates, sulfates, and aluminates.

The amount of the quick setting material is preferably 5 to 30 parts by weight, more preferably 7 to 20 parts by weight, based on 100 parts by weight of cement. If the amount is less than 5 parts by weight, sufficient initial coagulation may not be obtained. If the amount exceeds 30 parts by weight, the long-term strength development may be reduced, the pipes and the like may be clogged, and economically disadvantageous.

In the present invention, in order to improve properties such as slump before setting and hardening of cement concrete and strength properties after setting and hardening, a water reducing agent, a thickener, an ultrafine powder, and one or more selected from the group consisting of fibrous substances. It is preferred to use two or more admixtures.

水 The water reducing agent is used to improve the fluidity of cement concrete and the dispersion stability of the quick-setting material, and any of liquid and powder forms can be used. Examples of the water reducing agent include polyol derivatives, lignin sulfonates and derivatives thereof, and high-performance water reducing agents. One or more of these may be used. Among these, a high-performance water reducing agent is preferred in terms of high strength development and dispersion stability.

The use of a high performance water reducing agent can reduce the amount of quick-setting material, and the amount of generated dust and the rebound rate can be extremely reduced.

Examples of the high-performance water reducing agent include a formalin condensate of an alkyl allyl sulfonate, a formalin condensate of a naphthalene sulfonate, a formalin condensate of a melamine sulfonate, and a polycarboxylic acid polymer compound. Any of powder forms can be used, and one or two or more of these may be used. Among these, a formalin condensate of a naphthalene sulfonate, a formalin condensate of a melamine sulfonate, and a polycarboxylic acid-based polymer compound are preferable in terms of great effect.

(5) The amount of the water reducing agent used is preferably 0.05 to 3 parts by weight, more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of cement. Less than 0.05 parts by weight has no effect. If it exceeds 3 parts by weight, the fluidity of cement concrete increases, but the cement concrete becomes viscous and adheres to the pumping pipes and the rotating blades of the mixer, resulting in workability. May decrease, or the strength may decrease.

粘 Thickeners are those that give viscosity to cement concrete, prevent dripping immediately after spraying, reduce the rebound rate, and suppress dust generation. Examples of the thickener include celluloses such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, and hydroxyethylethylcellulose, alginic acid, sodium alginate, β-1,3-glucan, pullulan, and guar gum. , Casein, and polysaccharides such as welan gum, vinyl polymers such as vinyl acetate, ethylene, vinyl chloride, methacrylic acid, acrylic acid, sodium acrylate, and unsaturated carboxylic acids, and copolymers thereof, and vinyl acetate polymer. Emulsions, such as those obtained by saponifying a copolymer or a copolymer thereof and modifying the copolymer into a polyvinyl alcohol skeleton, and the like, may be used, and one or more of these may be used. Among these, celluloses are preferable because they hardly inhibit initial setting.

(4) The amount of the thickener used is preferably 0.001 to 0.5 part by weight, more preferably 0.005 to 0.3 part by weight, based on 100 parts by weight of cement. If it is less than 0.001 part by weight, the viscosity of the cement concrete is small and dripping occurs when spraying, and the rebound rate increases. If it exceeds 0.5 part by weight, the viscosity of the cement concrete increases and the pumpability of the cement concrete increases. There is a possibility that a hindrance will be caused and the strength expression will be impaired.

Ultra fine powder refers to powder having an average particle size of 10 μm or less, and has an effect of reducing the amount of cement, the amount of dust, and the rebound rate, and improving the pumpability of cement concrete. Examples of the ultrafine powder include fine powder slag, fine powder fly ash, bentonite, metakaorion, and silica fume. Among these, silica fume is preferable in terms of strength development.

使用 The use amount of the ultrafine powder is preferably 1 to 50 parts by weight, more preferably 2 to 30 parts by weight, based on 100 parts by weight of cement. If the amount is less than 1 part by weight, there is no effect, and if it exceeds 50 parts by weight, the setting and the curing may be delayed.

Fibrous substances improve the impact resistance and elasticity of cement concrete, and can be used either inorganic or organic.

Examples of the inorganic fibrous substance include glass fiber, carbon fiber, rock wool, asbestos, ceramic fiber, and metal fiber, and examples of the organic fibrous substance include vinylon fiber, polyethylene fiber, polypropylene fiber, and polyacryl fiber. , Cellulose fibers, polyvinyl alcohol fibers, polyamide fibers, pulp, hemp, wood wool, wood chips and the like. Among these, metal fibers and vinylon fibers are preferable in terms of economy.

The length of the fibrous substance is preferably 50 mm or less, more preferably 30 mm or less, in view of pumpability, mixing property and the like. If it exceeds 50 mm, the cement concrete may be blocked during the pumping.

使用 The amount of the fibrous substance to be used is preferably 0.5 to 3 parts by volume, more preferably 0.7 to 2 parts by volume, per 100 parts by volume of cement concrete. If the amount is less than 0.5 parts by volume, there is no effect. If the amount exceeds 3 parts by volume, the pumpability is reduced and the effect may be lost.

Furthermore, in the present invention, in order to delay the setting time of cement concrete, an organic acid or a salt thereof, a mixture of an organic acid or a salt thereof and a carbonate, a phosphate, a boric acid or a salt thereof, and alcohols May be used.

水 の The amount of water used in the sprayed cement concrete of the present invention is preferably 35% or more, more preferably 40 to 60%, in terms of water / cement from the viewpoint of strength development. If it is less than 35%, the cement concrete cannot be sufficiently mixed, and if it exceeds 60%, the strength developability may be reduced.

骨 The aggregate used as required in the present invention preferably has a low water absorption and a high aggregate strength. The fine aggregate ratio and the maximum size of the aggregate are not particularly limited as long as they can be sprayed. As fine aggregate, river sand, mountain sand, lime sand, silica sand, or the like can be used, and as coarse aggregate, river gravel, mountain gravel, lime gravel, or the like can be used.

吹 In the spraying method of the present invention, a conventionally used spraying equipment can be used. As the spraying method of the present invention, various spraying methods according to required physical properties, economy, workability, and the like are possible.

As the spraying method of the present invention, a dry spraying method can also be applied, but there is a possibility that the amount of dust increases, so a wet spraying method in which water is previously added to the cement concrete side and kneaded before using the quick-setting material is used. It is preferred to use.

As a wet spraying method, cement, fine aggregate, coarse aggregate, and water are added and kneaded to form sprayed concrete, which is air-poured, and a Y-shaped pipe is provided in the middle, and a quick-setting material supply device is provided from one of the pipes. A method in which the quick-setting material is pneumatically fed, mixed and mixed to form quick-setting wet-sprayed concrete, and sprayed.

The admixture can be added to either the cement concrete side or the quick setting material side, may be used only on one side, or may be used on both sides, but in terms of improving strength, preventing rebound, and setting control, It is preferably added to the cement concrete side. In particular, it is more preferable to add a water reducing agent to the cement concrete side in advance and use it in order to reduce the unit water amount and improve the strength development. There is no problem as long as the quick-setting spray concrete containing these materials is finally sprayed.

In the spraying method of the present invention, conventionally used spraying equipment and the like can be used. Usually, the spray pressure is 2-5 kg / cm ^{2 and the} spray speed is 4-20 m ³ / h.

The spraying equipment is not particularly limited as long as the spraying is sufficiently performed. For example, Ariver's trade name “Alibr 280” or the like is used for pumping sprayed cement concrete, and quick-setting material is used for pumping quick-setting material. A pumping device "Natom Cleat" or the like can be used.

Hereinafter, the present invention will be described in detail with reference to examples.

(Example 1)
The unit quantity of each material, cement 450 kg / m ^3, fine aggregates 1002kg / m ^3, coarse aggregate 671kg / m ^3, and a spraying concrete was prepared as a water 225 kg / m ^3, which concrete pumping machine "Ariba 280 ”. From one of the Y-tubes provided in the middle of pneumatic feeding of shotcrete, aluminate and calcium aluminate and sulfate in the amount shown in Table 1, and aluminate and calcium aluminate and sulfate in total 100 parts by weight The quick-setting material consisting of 6 parts by weight was added to the shotcrete by a quick-setting material addition device "NATOM CLEAT" so as to be 10 parts by weight with respect to 100 parts by weight of cement to prepare a quick-setting sprayable concrete. This quick setting sprayed concrete was evaluated. Table 1 shows the results.

(Material used)
Cement: ordinary Portland cement, commercial product, Blaine value 3200 cm ² / g, specific gravity 3.16
Fine aggregate: Lime sand from Aomi, Niigata Prefecture, surface water rate 3.1%, specific gravity 2.64
Coarse aggregate: Gravel from Himekawa, Itoigawa City, Niigata Prefecture, surface dry condition, specific gravity 2.65, maximum aggregate size 10mm
Calcium aluminates: those corresponding to C ₁₂ A ₇ composition, amorphous, Blaine value of 6050 cm ² / g
Sulfate a: pulverized product of commercial anhydrous gypsum, Blaine value 5900 cm ² / g
Sulfate b: pulverized commercial gypsum dihydrate, Blaine value 5200 cm ² / g
Sulfate c: Commercially pulverized aluminum sulfate, Blaine value 5900 cm ² / g
Aluminate: sodium aluminate, commercial product, loss on ignition 2.1% by weight, 90% particle size 0.2mm

(Measuring method)
Compressive strength: Compressive strength for one hour of age is as follows. A pin installed on a pull-out mold having a width of 25 cm x a length of 25 cm is covered with quick-setting sprayable concrete from the surface of the pull-out mold, and the pin is pulled out from the back side of the mold. The pull-out strength at that time was determined, and the compressive strength was calculated from the formula of (compression strength) = (pull-out strength) × 4 / (sample contact area). The compressive strength after 1 day of material age is measured by spraying quick-setting spray concrete onto a mold 50 cm wide x 50 cm long x 20 cm thick, and collecting a sample of 5 cm diameter x 10 cm length with a 20-ton pressure machine. Then, the compressive strength was determined.

(Example 2)
100 parts by weight of cement comprising 50 parts by weight of calcium aluminate, 50 parts by weight of sulfate a, and aluminate in the amount shown in Table 2 with respect to 100 parts by weight of the total of calcium aluminate and sulfate, The same procedure as in Example 1 was carried out except that 10 parts by weight of the concrete was used as a quick setting sprayable concrete. Table 2 shows the results.

(Example 3)
50 parts by weight of calcium aluminates, 50 parts by weight of sulfate a, and a quick setting material consisting of 6 parts by weight of aluminate with respect to 100 parts by weight of calcium aluminates and sulfate in total, 100 parts by weight of cement The procedure was performed in the same manner as in Example 1 except that the quick-setting spray concrete was used using the amounts shown in Table 3. Table 3 shows the results.

(Example 4)
To 100 parts by weight of cement, a water reducing agent was mixed in an amount shown in Table 4 to give a shotcrete, and 50 parts by weight of calcium aluminates, 50 parts by weight of sulfate a, and a total of 100 parts by weight of calcium aluminates and sulfates The slump was measured in the same manner as in Example 1, except that 10 parts by weight of a quick-setting material consisting of 6 parts by weight of aluminate was mixed with 100 parts by weight of cement to give a quick-setting sprayable concrete. did. Table 4 shows the results.

(Material used)
Water reducer a: Commercial naphthalene sulfonate-based formalin condensate water reducer A: Commercial polycarboxylic acid-based polymer compound

(Measuring method〕
Slump: According to JIS A 1101.

(Example 5)
To 100 parts by weight of cement, a thickener was mixed in an amount shown in Table 5 to give a shotcrete. 50 parts by weight of calcium aluminates, 50 parts by weight of sulfate a, and a total of 100 parts by weight of calcium aluminates and sulfates The procedure was the same as in Example 1, except that 10 parts by weight of a quick setting material consisting of 6 parts by weight of aluminate was mixed with 100 parts by weight of cement to give quick setting sprayable concrete. , Sagging, and pumpability were measured. Table 5 shows the results.

(Material used)
Thickener i: methylcellulose thickener ii: hydroxypropylcellulose

(Evaluation method)
Dust amount: Quick-setting sprayed concrete was sprayed at a spraying speed of 4 m ³ / h for 30 minutes onto a simulated tunnel 3.5 m high and 2.5 m wide made of an iron plate in an arch shape. Every 10 minutes, the amount of dust was measured at a fixed position 3 m from the spray location, and the average value of the measured values was shown.
Sag: Rapid-setting spraying concrete was sprayed at a spraying speed of 4 m ³ / h for 30 minutes onto a 3.5 m high and 2.5 m wide simulated tunnel made of an iron plate and observed. The sample was evaluated as と し when no sagging occurred, as O when slight sagging occurred, and as × when sagging occurred a lot.
Pumpability: Quick-setting sprayed concrete was sprayed at a spraying speed of 4 m ³ / h at a discharge pressure of 4 kg / cm ² using a pressure pipe for 30 minutes, and the pressure in the pressure pipe was measured. Also when the pressure in the pumping tube is 4.0~5.5kg / cm ² ◎, it becomes more than 6.0 kg / cm ^2, which tends to closed pumping tube 4 by impacting the pumping tube. The case where the pressure was 0 to 5.5 kg / cm ² was rated as 、, and the case where the pressure feeding tube was closed and the pressure was not 4.0 to 5.5 kg / cm ² even when an impact was applied to the pressure feeding tube was rated as x.

(Example 6)
100 parts by weight of cement and 100 parts by weight of ultrafine powder were mixed as shown in Table 6 to give a total of 100 parts by weight of shotcrete, 50 parts by weight of calcium aluminate, 5 parts by weight of sulfate a, and calcium aluminate and sulfate. On the other hand, the rebound rate was measured in the same manner as in Example except that 10 parts by weight of a quick-setting material composed of 6 parts by weight of aluminate was mixed with 100 parts by weight of cement to obtain a quick-setting sprayable concrete. . Table 6 shows the results.

(Material used)
Ultrafine powder α: Commercial silica fume, average particle size 10 μm or less Ultrafine powder β: Commercial metakaolin, average particle size 10 μm or less

(Measuring method)
Rebound rate: Rapid-setting sprayed concrete was sprayed at a spraying speed of 4 m ³ / h for 30 minutes onto a simulated tunnel having a height of 3.5 m and a width of 2.5 m. After spraying, measure the amount of quick-setting spray concrete that fell without adhering, and (rebound rate) = (weight of quick-setting spray concrete that did not adhere to the simulated tunnel during spraying) / The weight was calculated from the formula of (weight of quick-setting spray concrete used for spraying) × 100 (%).

(Example 7)
In 100 parts by volume of concrete, the fibrous substances in the amounts shown in Table 7 were mixed to give a sprayed concrete, and 50 parts by weight of calcium aluminates, 50 parts by weight of sulfate a, and 100 parts by weight of calcium aluminates and sulfate in total On the other hand, the same procedure was performed as in Example 1 except that 10 parts by weight of a quick-setting material composed of 6 parts by weight of aluminate was mixed with 100 parts by weight of cement to obtain a quick-setting sprayable concrete. It was measured. Table 7 shows the results.

(Material used)
Fibrous substance A: vinylon fiber, fiber length 10 mm
Fibrous material B: steel fiber, fiber length 30 mm

(Evaluation method)
Impact resistance: Shotcrete after 1 hour of age is sprayed onto a 20 cm wide, 20 cm long, 2 cm thick formwork, the bottom is removed and placed on flattened standard sand, weighing 50 g Was dropped from a height of 50 cm. When the number of drops was less than 5 times, cracking and breaking occurred were evaluated as X, cracked but not broken as O, and cracking as ◎.

(Example 8)
0.5 part by weight of water reducing agent a, 100 parts by weight, a thickener i in the amount shown in Table 8 and ultrafine powder α, and fibrous substance A in an amount shown in Table 8 in 100 parts by volume of concrete were mixed. Then, a quick-setting material consisting of 50 parts by weight of calcium aluminate, 50 parts by weight of sulfate a, and 6 parts by weight of aluminate with respect to 100 parts by weight of calcium aluminate and sulfate in total is added to cement. Except that 10 parts by weight were mixed with 100 parts by weight to obtain a quick-setting sprayed concrete, the same procedure as in Example 1 was carried out, and the slump, rebound rate, and impact resistance were measured. Table 8 shows the results.

(Example 9)
Cement 450 kg / m ³ , fine aggregate ratio 60%, and the amount of water used in the sprayed concrete were as shown in Table 9 with respect to 100 parts by weight of the cement. 5 parts by weight to give a shotcrete, 50 parts by weight of calcium aluminate, 50 parts by weight of sulfate a, and 6 parts by weight of 30 aluminate per 100 parts by weight of calcium aluminate and sulfate in total Of the quick-setting material consisting of 100 parts by weight of cement was mixed with 10 parts by weight of cement to give a quick-setting sprayable concrete, and slump was measured in the same manner as in Example 1. Table 9 shows the results.

By using the quick-setting material of the present invention, it is possible to obtain a sprayed material whose strength after a material age of 28 days does not easily decrease, and to increase the strength. Therefore, it is most suitable as a spraying material for unstable ground, and it is economical because the spraying thickness can be reduced.

Claims (4)

40 to 60% by weight of calcium aluminate, 60 to 40% by weight of sulfate, and less than 10 parts by weight and 1 part by weight or more of powdered alkali metal aluminate based on 100 parts by weight of calcium aluminates and sulfate in total A method for mixing quick-setting sprayable cement concrete, comprising mixing a quick-setting material for a spraying material, comprising: and a cement concrete obtained by mixing cement and water. 40 to 60% by weight of calcium aluminate, 60 to 40% by weight of sulfate, and less than 10 parts by weight and 1 part by weight or more of powdered alkali metal aluminate based on 100 parts by weight of calcium aluminates and sulfate in total A method of wet-mixing quick-setting sprayed cement concrete, which comprises mixing a quick-setting material for spraying material containing: and a cement concrete obtained by mixing cement and water. One or more admixtures selected from the group consisting of a water reducing agent, a thickener, an ultrafine powder, and a fibrous substance are further added to the quick-setting material for the spray material and / or the cement concrete. The method for mixing quick-setting sprayed cement concrete according to claim 1. One or more admixtures selected from the group consisting of a water reducing agent, a thickener, an ultrafine powder, and a fibrous substance are further added to the quick-setting material for the spray material and / or the cement concrete. The method for wet mixing of quick-setting sprayed cement concrete according to claim 2.