JPH1059760A - Spray material and spraying method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stable spray material having good initial strength and long-term strength and also to provide a spraying method using the spray material. SOLUTION: In this spraying method, a spray material which contains cement mortal consisting essentially of cement and gypsum and a quick setting agent consisting essentially of calcium aluminate and gypsum, is used. At this time, optionally, an alkali aluminate or alkali carbonate is further added to the quick setting agent, and also, an admixture(s) selected from setting retarders, setting accelerators, water-reducing agents, superfine powders and fibrous materials is further added to the spray material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spraying material sprayed on a ground surface exposed in a tunnel such as a road, a railroad, and a headrace, and a spraying method using the same.

[0002]

2. Description of the Related Art Conventionally, a method of spraying quick-setting concrete in which a quick-setting agent is mixed with concrete has been performed in order to prevent collapse of exposed ground such as tunnel excavation (Japanese Patent Publication No. Sho 5).
No. 2-4149). In this method, spray concrete is usually produced at a cement, aggregate, and water metering and mixing plant installed at the excavation site, transported by an agitator truck, pumped by a concrete pump, and installed at the junction pipe. This is a method of mixing with a quick-setting agent pumped from the other side and spraying it as a quick-setting sprayable concrete on the ground surface to a predetermined thickness. According to this method, the rebound (bounce) rate, which is the ratio of the amount of falling without adhering to the ground and the amount of spraying, is as large as 15 to 30% by weight. I was worried about the effects of For this purpose, there has been a demand for a method of reducing the rebound rate and dust, but at present, there is no sufficiently satisfactory spraying material or spraying method, and improvement thereof has been strongly desired.

[0003] In addition, although the concrete containing a quick-setting agent, which has been conventionally used, has a good rise in the initial strength as compared with the concrete containing no quick-setting agent,
The long-term strength was about 30 to 50% smaller than that of the concrete containing no quick-setting agent, and the strength-generating properties tended to be poor. Still, its initial strength is
In the construction method, the strength is sufficient in most cases to prevent the collapse of the ground, and in the considerably unstable ground, it has been dealt with by increasing the sprayed thickness. However, increasing the spray thickness is not preferable in terms of economy and work efficiency. In particular, in the excavation of large section tunnels, it is particularly important to improve the strength of shotcrete to reduce the sprayed thickness, shorten the construction time and the excavation cycle in consideration of economy and work efficiency. It was a point.

Hitherto, as a method for achieving high strength of shotcrete, there has been proposed a method in which a quick-setting agent in which gypsum and calcium aluminate are previously mixed is mixed with shotcrete and sprayed ( JP 50
No. 16717, JP-A-50-16718,
And JP-A-50-25623).

[0005]

However, in this method, a quick setting agent obtained by mixing gypsum and calcium aluminate is required to have a higher setting force and a higher initial strength by 10 parts by weight or more per 100 parts by weight of cement. , It was necessary to add as much as 20 parts by weight or more. For this reason, if it is necessary to interrupt the work during spraying and add a quick-setting agent, if the amount of dust generated increases, or if the quick-setting agent runs out during the spraying operation, concrete However, there is a problem in that it becomes dangerous due to dropping, causing problems in terms of workability, health and safety, and economy. It is considered that the quick-setting admixture of gypsum and calcium aluminate reacts with the water or free SO ₃ contained in gypsum on the surface of the calcium aluminate, resulting in low reactivity. As a result, as the storage period is prolonged, the quick-setting force is reduced, and the shotcrete falls from the tunnel, or the sprayed concrete does not adhere when there is spring water, and the rebound rate increases. And other issues.

The present inventor has studied various problems in imparting high strength to shotcrete. As a result, the long-term strength has been improved by spraying using a shot material in which cement and gypsum are premixed. The present invention has been completed based on the finding that the above-mentioned problems can be solved.

[0007]

That is, the present invention is characterized in that a cement mortar mainly composed of cement and gypsum is mixed with a calcium aluminate and a quick setting agent mainly composed of gypsum. A spraying material, wherein calcium aluminate and a quick setting agent containing alkali aluminate and / or alkali carbonate as a main component are used, and further a setting retarder,
A spraying material comprising one or more admixtures selected from the group consisting of a setting accelerator, a water reducing agent, an ultrafine powder, and a fibrous substance; A spraying method characterized by being used.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

As the cement used in the present invention, various portland cements which are generally commercially available, such as ordinary, fast, moderate heat and ultra fast, and various types of portland cement mixed with fly ash, blast furnace slag, etc. Mixed cement, commercially available fine particle cement and the like can be mentioned, and various Portland cements and various mixed cements can be used after pulverized.

The gypsum used in the present invention is mixed with cement to increase the strength of shotcrete, and examples thereof include anhydrous gypsum, hemihydrate gypsum and dihydrate gypsum. Two or more can be used. Among these, anhydrous gypsum is preferred from the viewpoint of strength development. The particle size of gypsum is generally good for use in cement and the like, for example, 3000 cm ² /
g and more preferably more than 3000 cm ² / g. In the present invention, in order to obtain a quick setting force, a mixture of cement and gypsum (hereinafter referred to as cement mortar) and a quick setting agent of calcium aluminate and gypsum are mixed. The cement mortar used in the present invention refers to a general term for cement paste, mortar, and concrete, and any of a dry cement mortar in a dry state that does not mix with water and a cement mortar mixed with water. Can also be used.

The amount of gypsum to be added to the cement mortar is preferably 1 to 25 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of cement. If the amount is less than 1 part by weight, there is no long-term strength development, and if it exceeds 25 parts by weight, the initial setting is delayed, the adhesion to the ground may be reduced, or the concrete may be expanded and destroyed for a long period of time. The amount of gypsum to be added to the quick setting agent is preferably 50 to 200 parts by weight, and more preferably 80 to 150 parts by weight based on 100 parts by weight of calcium aluminate.
Parts by weight are more preferred. If the amount is less than 50 parts by weight, there is no effect. If the amount exceeds 200 parts by weight, quick-setting properties may be reduced.

When the cement mortar and the quick setting agent are mixed, the total amount of gypsum used is preferably 1 to 40 parts by weight, more preferably 5 to 25 parts by weight, based on 100 parts by weight of cement. If the amount is less than 1 part by weight, strength cannot be expected, and if it exceeds 40 parts by weight, the concrete may expand and break.

The quick-setting agent used in the present invention contains calcium aluminate and gypsum as main components. In the present invention, by using a cement mortar in which cement and gypsum are mixed, it is possible to reduce the amount of a quick setting agent in which calcium aluminate and gypsum are mixed. The calcium aluminate used in the present invention is C
A material obtained by heat-treating a mixture of aO raw material, Al ₂ O ₃ raw material, etc., by firing in a kiln or melting in an electric furnace, etc. Minutes. As a mineral component of calcium aluminate, when CaO is C and Al ₂ O ₃ is A, a calcium aluminate heat-treated product represented by C ₃ A, C ₁₂ A ₇ , CA, CA ₂ or the like is crushed. Is mentioned. Further, as another mineral component, SiO ₂
Calcium aluminosilicate containing C _{11, wherein} one CaO of C ₁₂ A ₇ is replaced with a halide such as CaF _2.
A ₇ · CaX ₂ (X is a halide such as fluorine), SO
Examples include C ₄ A ₃ .SO ₃ containing _three components, alumina cement, and calcium aluminate in which alkali metals such as sodium, potassium, and lithium are partially dissolved. Among these, amorphous calcium aluminate obtained by quenching a heat-treated product corresponding to the C ₁₂ A ₇ composition is preferable in terms of reaction activity. The particle size of calcium aluminate has a Blaine value of 30 in terms of quick setting property and initial strength development.
It is preferably at least 00 cm ² / g, more preferably at least 4000 cm ² / g. If it is less than 3000 cm ² / g, the quick setting property and the initial strength development property may be reduced. The amount of calcium aluminate used is 1 to 20 parts by weight based on 100 parts by weight of cement.
It is preferably 5 parts by weight, more preferably 5 to 15 parts by weight. 1
If the amount is less than 10 parts by weight, the initial setting does not occur, and if the amount exceeds 20 parts by weight, the long-term strength development may be impaired.

In the present invention, it is preferable to use an alkali aluminate or an alkali carbonate together with a quick-setting agent containing calcium aluminate and gypsum as main components from the viewpoint of initial setting and improvement of initial strength.

The alkali aluminate used in the present invention promotes initial coagulation, and includes lithium aluminate,
Examples thereof include sodium aluminate and potassium aluminate, and one or more of these can be used.
The amount of the alkali aluminate to be used is preferably 0.1 to 50 parts by weight, more preferably 2 to 25 parts by weight, based on 100 parts by weight of calcium aluminate. If the amount is less than 0.1 part by weight, there is no effect, and if it exceeds 50 parts by weight, the long-term strength development may be impaired.

The alkali carbonate used in the present invention improves the initial strength, and includes sodium carbonate, potassium carbonate, sodium bicarbonate, etc., and one or more of these can be used. It is. The amount of the alkali carbonate to be used is preferably 0.1 to 200 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of calcium aluminate.
0 parts by weight is more preferred. If the amount is less than 0.1 part by weight, there is no effect, and if it exceeds 200 parts by weight, the long-term strength may be reduced. In addition, it is preferable to use an alkali carbonate and an alkali aluminate in combination from the viewpoint of improving the quick setting force.

The amount of the quick setting agent used in the present invention is preferably 1 to 20 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of cement. If the amount is less than 1 part by weight, initial coagulation hardly occurs, and if it exceeds 20 parts by weight, the long-term strength development may be impaired.

According to the present invention, one or more selected from the group consisting of a setting retarder, a setting accelerator, a water reducing agent, an ultrafine powder, and a fibrous substance, in terms of improving the properties of the sprayed material. It is preferable to use an admixture together.

The setting retarder is one that delays the setting time of cement mortar, and examples thereof include organic acids and alkali carbonates.

The organic acids include gluconic acid, tartaric acid,
Examples thereof include citric acid, malic acid, lactic acid, and salts thereof, and one or more of these can be used. Among these, citric acid is preferred because it hardly inhibits the strength expression. The amount of the organic acids used is preferably 0.01 to 3 parts by weight, and
2 parts by weight is more preferred. If the amount is less than 0.01 part by weight, the effect is not obtained. If the amount is more than 3 parts by weight, the curing is excessively delayed, which may result in poor curing.

Examples of the alkali carbonate include sodium carbonate, potassium carbonate, and sodium bicarbonate.
One or more of these can be used. The amount of alkali carbonate used is based on 100 parts by weight of cement.
It is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight. Less than 0.01 part by weight has no effect and 1
If the amount exceeds 0 parts by weight, curing may be excessively delayed, resulting in poor curing.

Further, it is preferable to mix an organic acid and an alkali carbonate from the viewpoint of improving the strength of the cement mortar after delaying the setting thereof. The amount of the alkali carbonate used in this case is 10 parts by weight based on 100 parts by weight of the organic acid.
It is preferably from 1000 to 1000 parts by weight, more preferably from 50 to 700 parts by weight. Less than 10 parts by weight has no effect.
If the amount is more than 100 parts by weight, curing may be excessively delayed, resulting in poor curing. The amount of the mixture of the organic acid and the alkali carbonate is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the cement.
If the amount is less than 0.01 part by weight, the effect is not obtained. If the amount is more than 10 parts by weight, curing is excessively delayed, which may result in poor curing.

The setting accelerator refers to an agent that promotes initial setting, and includes alkali metal hydroxides such as sodium hydroxide, slaked lime, alum, and the like. One or more of these can be used. is there. The amount of the setting accelerator used is preferably 0.05 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of cement. If the amount is less than 0.05 part by weight, there is no effect, and if it exceeds 20 parts by weight, there is a possibility that the long-term strength expression property is not improved.

The water reducing agent is used to improve the fluidity of the cement mortar, and any of a liquid or a powder can be used, and a polyol derivative, a lignin sulfonate or a derivative thereof, and And high performance water reducing agents. A high-performance water reducing agent is preferred from the viewpoint of imparting high strength. The high-performance water reducing agent can reduce the sprayed thickness and improve the quick-setting force, so that the amount of the quick-setting agent can be reduced. Further, since the amount of generated dust and the rebound rate can be reduced, the spraying operation can be performed efficiently. Examples of the high performance water reducing agent include a formalin condensate of an alkyl allyl sulfonate, a naphthalene sulfonate, and a melamine sulfonate, and a polycarboxylic acid polymer compound. Can be used, and either liquid or powder can be used. The use amount of the high-performance water reducing agent is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of cement as solids. If the amount is less than 0.05 part by weight, there is no effect. If the amount exceeds 5 parts by weight, the viscosity of the cement mortar is too strong, and the workability may be reduced.

The ultrafine powder refers to a powder having an average particle diameter of 10 μm or less, which can reduce the amount of cement and dust and improve the pumpability of concrete. Ultra fine powder includes fine slag, fly ash, bentonite, kaolin,
And silica fume. Among these,
Silica fume is preferred in terms of strength development. The use amount of the ultrafine powder is 1 to 100 with respect to 100 parts by weight of cement.
Part by weight is preferable, and 2 to 30 parts by weight is more preferable. 1
If the amount is less than 100 parts by weight, there is no effect. If the amount is more than 100 parts by weight, setting and curing may be delayed.

As the fibrous substance, any of inorganic and organic substances can be used, which improves the impact resistance and elasticity of the shotcrete. Examples of the inorganic fiber include glass fiber, carbon fiber, rock wool, asbestos, ceramic fiber, and metal fiber, and examples of the organic fiber include vinylon fiber, polyethylene fiber, polypropylene fiber, polyacryl fiber, and cellulose fiber. Polyvinyl alcohol fiber, polyamide fiber, pulp, hemp, wood wool,
And wood chips, and one or more of these can be used. Among these, metal fibers and vinylon fibers are preferable in terms of economy. The length of the fibrous substance is preferably 100 mm or less, more preferably 0.5 to 60 mm, in consideration of the pumpability, the mixing property, and the like. If it is less than 0.5 mm, there is no effect, and if it exceeds 100 mm, the sprayed concrete may be blocked during pumping. The amount of the fibrous substance used is preferably 0.5 to 7 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the cement. If the amount is less than 0.5 part by weight, there is no effect, and if the amount exceeds 7 parts by weight, strength development may be impaired.

The amount of water used is preferably 35 to 60 parts by weight, more preferably 40 to 50 parts by weight, based on 100 parts by weight of cement. If the amount is less than 35 parts by weight, kneading cannot be carried out with a mixer, and if it exceeds 60 parts by weight, strength cannot be obtained.

The aggregate used in the present invention, such as coarse aggregate and fine aggregate, preferably has a low water absorption and a high aggregate strength, but is not particularly limited. The coarse aggregate preferably has a maximum diameter of 20 mm or less, and more preferably has a maximum diameter of 5 to 15 mm in consideration of pumpability. Fine aggregates having a maximum diameter of 5 mm or less are preferable.
Mountain sand, lime sand, silica sand, and the like.

Examples of the mixing method include a method in which a specific amount of gypsum is previously mixed with cement, and a method in which gypsum is added at the time of concrete kneading. further,
Sulfur trioxide (SO) in cement specified by JIS
_Since the content of ₃ ) is about 3.0 to 4.5% by weight, a method of mixing gypsum in an amount exceeding this JIS specified value at the time of cement production at a cement production plant can also be mentioned.

In the spraying method of the present invention, required physical properties,
From the economic point of view, workability, etc., it is possible to spray as dry cement mortar containing cement, cement mortar containing cement and water, or paste or concrete thereof, either dry spray method or wet spray method Can be used. In the dry spraying method, cement, gypsum, quick-setting agent, and, if necessary, an aggregate are mixed, air-fed, and, for example, water is added from one side of a Y-tube and sprayed in a wet state. And a method in which cement and, if necessary, an aggregate are mixed and pneumatically fed, and a spraying material is added in the order of gypsum, a quick setting agent, and water, and sprayed in a wet state. As a wet spraying method, cement, gypsum, water, and, if necessary, an aggregate are mixed and kneaded, air-fed and, for example, a quick-setting agent is added from one of the Y-shaped pipes and sprayed. Method and the like.

The setting accelerator, setting retarder, ultrafine powder, and fibrous substance can be mixed on either the cement mortar side or the quick setting agent side, and may be used on only one side or on both sides. However, it is preferably added to the cement mortar side in terms of improving strength, preventing rebound, and setting control. There is no problem if the shotcrete mixed with these materials is finally sprayed. In the spraying method of the present invention, conventionally used spraying equipment and the like can be used.
Normally, the spray pressure is 3-5 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, Aliver Co., Ltd. product name “Aliver 280” or the like is used for concrete pumping, and a quick-setting agent pumping device “ Nattom Cleat "or the like can be used.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.

(Example 1) A unit amount of each material was cement 4
00 kg / m ³ , fine aggregate 1055 kg / m ³ , coarse aggregate 713 kg / m
³ and water at 200 kg / m ^3, and 100 parts by weight of cement were mixed with 10 parts by weight of gypsum to give a shotcrete. This is used as a concrete pumping machine "Aliver-28".
0 ", and from one of the Y-tubes provided in the middle,
A quick-setting admixture obtained by mixing 100 parts by weight of calcium aluminate and gypsum in the amount shown in Table 1 was pumped by a quick-setting additive adding machine “Denanatom Cleat” so as to be 10 parts by weight with respect to 100 parts by weight of cement. They were mixed and mixed to give quick-setting sprayable concrete. This quick-setting sprayed concrete was sprayed on a formwork at a spraying speed of 4 m ³ / h, and the compressive strength of each material age was measured. Table 1 shows the results.

(Materials used) Cement: Commercial ordinary Portland cement, specific gravity 3.
16 Gypsum: Commercially-pulverized anhydrous gypsum, Blaine value 5
400cm ² / g fine aggregate: sand from Himekawa, Niigata Prefecture, surface water 5%, maximum diameter 5mm
Below, specific gravity 2.61 coarse aggregate: gravel from Himekawa, Niigata Prefecture, surface dry state, maximum diameter 15m
m or less, specific gravity 2.65 calcium aluminate: main component C ₁₂ A ₇ , Blaine value 6000 cm ² / g, specific gravity 2.90

(Measurement Method) Compressive strength: The prepared shotcrete was sprayed onto a 25 cm wide × 25 cm long pull-out formwork and a 50 cm wide × 50 cm long × 20 cm thick formwork. The material age of 3 hours or less was measured using a pull-out mold specimen. Cover the pin with spray concrete from the surface of the pull-out formwork, pull out the pin from the back side of the formwork, find the pullout strength at that time,
The compressive strength was calculated from the formula (compressive strength) = (pull-out strength) × 4 / (specimen surface area). 5 days old after 1 day
A test piece having a diameter of 5 cm and a length of 10 cm collected from a mold having a size of 0 cm x a length of 50 cm x a thickness of 20 cm was measured with a 20-ton pressure machine,
The compressive strength was determined.

[0036]

[Table 1]

Example 2 100 parts by weight of cement and Table 2
Mix gypsum in the amount shown in the table to make shotcrete,
100 parts by weight of calcium aluminate and gypsum 100
The procedure was performed in the same manner as in Example 1 except that 10 parts by weight of the quick-setting admixture mixed with 100 parts by weight of the cement was mixed to give quick-setting sprayable concrete. Table 2 shows the results.

[0038]

[Table 2]

Example 3 Calcium aluminate 10
0 parts by weight, 100 parts by weight of gypsum, and 10 parts by weight of a quick-setting admixture of an alkali aluminate and an alkali carbonate mixed in the amounts shown in Table 3 with respect to 100 parts by weight of cement, quick-setting sprayable concrete Example 1 except that
The same was done. Table 3 shows the results.

(Materials used) Alkaline aluminate: Commercially available sodium aluminate Alkaline carbonate: Commercially available sodium carbonate

[0041]

[Table 3]

Example 4 Calcium aluminate 10
0 parts by weight, 100 parts by weight of gypsum, and 10 parts by weight of an alkali aluminate were mixed with cement 100
The procedure was performed in the same manner as in Example 1 except that the amount shown in Table 4 was mixed with the parts by weight to obtain a quick-setting sprayable concrete.
Table 4 shows the results.

[0043]

[Table 4]

Example 5 By changing the unit amount of cement, the amount of water used was changed to that shown in Table 5 with respect to 100 parts by weight of cement to give a shotcrete, and 100 parts by weight of calcium aluminate and gypsum Same as Example 1 except that 100 parts by weight and a quick-setting admixture of 10 parts by weight of an alkali aluminate were used as a quick-setting spray concrete by using 10 parts by weight with respect to 100 parts by weight of cement. went. Regarding shotcrete, the slump immediately after kneading was measured. Table 5 shows the results. (Measurement method) Slump: Measured according to JIS A1101.

[0045]

[Table 5]

(Example 6) The unit amount of each material was the same as in Example 1.
Similarly, 100 parts by weight of cement and 10 parts by weight of gypsum
To prepare dry concrete,
In a, it was carried into the spraying machine. Meanwhile, calcium aluminate
100 parts by weight, 100 parts by weight of gypsum, and aluminate
A quick setting agent mixed with 10 parts by weight of alkali salt
10 parts by weight for 100 parts by weight of cement in cleat
Dry concrete on a belt conveyor
Was added. Blowing dry concrete with quick-setting additive
Air is sent from the attachment machine, and water is
Add 47 parts by weight and dry spray
Work was carried out. As a result, there are no problems such as clogging of piping.
The spraying work was able to be carried out. Age 1 at that time
Compressive strength between 3.0 and 28 days is 3.0 N / mm^Two, 59.
2N / mm ^TwoMet.

For comparison, calcium aluminate
100 parts by weight and 10 parts by weight of alkali aluminate
The procedure was the same as in Example 6, except that a quick setting agent was used.
The compressive strength of 1 hour and 28 days respectively
3.9 N / mm^Two, 57.0 N / mm ^TwoIs a quick-setting agent
The long-term strength was better when c was added.

Example 7 100 parts by weight of cement, 10 parts by weight of gypsum, and the setting retarders and setting accelerators in the amounts shown in Table 6 were mixed to give shotcrete, 100 parts by weight of calcium aluminate and 100 parts by weight of gypsum Parts, and a quick-setting admixture obtained by mixing 10 parts by weight of sodium aluminate,
Wet spraying was carried out in the same manner as in Example 1, except that 10 parts by weight was mixed with 100 parts by weight of cement to obtain quick-setting sprayed concrete. Table 6 shows the results.

(Materials used) Set retarder: organic acids, citric acid, set retarder: alkali carbonate, sodium carbonate, set retarder: alkali carbonate, sodium bicarbonate set accelerator a: slaked lime set accelerator b: Alum

[0050]

[Table 6]

Example 8 100 parts by weight of cement, 10 parts by weight of gypsum, and a high-performance water reducing agent in the amount shown in Table 7 and ultrafine powder were mixed to give a shotcrete, and 100 parts by weight of calcium aluminate and 100 parts by weight of gypsum Part, and 10 parts by weight of sodium aluminate, and 10 parts by weight with respect to 100 parts by weight of cement to obtain a quick-setting sprayable concrete in the same manner as in Example 1, except that the composition is wet-sprayed. Construction was performed. Table 7 shows the results.

(Materials used) Water reducing agent A: Commercially available high-performance water reducing agent, formalin condensate of sodium salt of naphthalenesulfonic acid as main component Water reducing agent B: Commercially available high-performance water reducing agent, sodium salt of polycarboxylic acid as main component Ultra fine powder α: Commercially available Blast furnace slag pulverized product, average particle size 10μ
m or less Ultrafine powder β: Commercial silica fume, average particle size 4 μm Ultrafine powder γ: Commercial kaolin, average particle size 10 μm or less

(Measurement method) Rebound rate: Quick-setting sprayed concrete was sprayed onto a simulated tunnel having a height of 3.5 m and a width of 2.5 m for 30 minutes at a blowing speed of 4 m ³ / h. After spraying, measure the amount of shotcrete dropped without adhering, and (rebound rate) = (weight of shotcrete dropped without adhering to the simulated tunnel during spraying) / (used for spraying) Weight of sprayed concrete) × 100 (%).

[0054]

[Table 7]

(Example 9) 100 parts by weight of cement, 10 parts by weight of gypsum, and fibrous substances in the amounts shown in Table 8 were mixed to give shotcrete, and calcium aluminate 1
100 parts by weight of gypsum, 100 parts by weight of gypsum, and 10 parts by weight of sodium aluminate were mixed with cement 10
Wet spraying was carried out in the same manner as in Example 1 except that 10 parts by weight was mixed with 0 part by weight to obtain a quick-setting spray concrete. Table 8 shows the results.

(Materials used) Fibrous substance i: commercially available vinylon fiber, fiber length 30 mm Fiber ii: commercially available steel fiber, fiber length 30 mm

[0057]

[Table 8]

[0058]

By using the spray material of the present invention, the initial and long-term strength development can be greatly improved. or,
By adding gypsum to the cement mortar side, it is possible to reduce the amount of the quick-setting admixture obtained by mixing calcium aluminate and gypsum, and to prevent quality deterioration. Therefore, it is possible to greatly contribute to stabilization of workability and quality, and it is possible to make the sprayed thickness smaller than the conventional sprayed thickness, and it is possible to provide more stable sprayed concrete than before. Further, it is also possible to reduce the construction cost and the construction speed.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location // C04B 103: 14 (72) Inventor Isao Terashima 2209 Aomi, Aomi-cho, Nishikubiki-gun, Niigata Electrochemistry Aoki Watanabe, Industrial Co., Ltd. Industrial Co., Ltd.

Claims (4)

[Claims] 1. A spraying material comprising a cement mortar mainly composed of cement and gypsum, and a quick setting agent mainly composed of calcium aluminate and gypsum. 2. A spraying material according to claim 1, wherein calcium aluminate, gypsum and a quick-setting agent mainly composed of alkali aluminate and / or alkali carbonate are used. 3. A composition selected from the group consisting of a setting retarder, a setting accelerator, a water reducing agent, an ultrafine powder, and a fibrous substance.
The spray material according to claim 1 or 2, wherein the spray material comprises at least one kind or two or more kinds of admixtures. 4. A spraying method comprising using the spraying material according to claim 1.