JP3412794B2 - Spraying material and spraying method using it - Google Patents

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 water conduit, and a spraying method using the spraying material.
The cement mortar of the present invention is a general term for paste, mortar, and concrete.

[0002]

2. Description of the Related Art Conventionally, a spraying method of 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. 52).
-4149). This method is usually used to make spray concrete at a cement, aggregate, and water metering and mixing plant installed at an excavation site, transport it with an agitator car, and pump it with a concrete pump. Then, it is a method of mixing with a quick-setting agent sent from the other side and spraying it as quick-setting sprayed concrete on the ground surface to a predetermined thickness. With this method, the rebound (rebound) is the ratio of the amount of drop without adhering to the ground and the amount of spray.
The ratio is as high as 15 to 30% by weight, and there is a lot of dust and the working environment is bad, so there is concern about the influence of pneumoconiosis, etc., and a construction method with less rebound rate and dust was required, but at present it is still satisfactory. There is no spraying material or spraying method, and there has been a strong demand for improvement.

Conventionally used concrete containing a quick-setting admixture containing calcium aluminate, alkali aluminate, etc. as a main component has a higher initial strength than concrete containing no quick-setting admixture. Was good, but the long-term strength tended to be poorer, such as 30-50% lower than that of concrete containing no quick-setting agent. Still, its initial strength is
In the TM method, the strength is sufficient in most cases to prevent the ground from collapsing, and in fairly unstable ground, it has been dealt with by increasing the spray thickness. However, thickening the spray thickness is not very preferable in terms of economic efficiency and work efficiency. In particular, when excavating large-section tunnels, considering economic efficiency and work efficiency, it is particularly important to improve the strength of shotcrete, reduce the shot thickness, and shorten the construction time and excavation cycle. Become. If calcium aluminate is used as a quick-setting agent and the strength is increased for a short period of time, the amount of the quick-setting agent should be increased, but 10 parts by weight or more of the quick-setting agent should be mixed with 100 parts by weight of cement. Then, the mixing property of the quick-setting admixture with concrete deteriorates, and as a result, dust is generated more often, and it is necessary to replenish the quick-setting admixture during spraying because the amount of the quick-setting admixture is large. Therefore, there was a problem that workability was extremely deteriorated.

Furthermore, as a means for obtaining high strength after spraying and reducing the strength decrease as compared with concrete containing no quick-setting agent, a method of premixing gypsum and calcium aluminate has been proposed. (Japanese Patent Laid-Open No. 50
-16717, JP-A-50-16718, JP-A-50-
No. 25623).

[0005]

However, when using a quick-setting admixture containing calcium aluminate and gypsum, it is necessary to add 10% by weight or more to the cement, which results in higher quick-setting power and higher When the initial strength was required, it was necessary to add 20% by weight or more. Currently, when a quick-setting admixture is used, it is used in a method of transporting the quick-setting admixture with many materials in a long tunnel and at the same time manually dismantling it into the quick-setting admixture adding device, and also for reducing dust. In the wet spraying method, the quick-setting agent is pneumatically fed and continuously mixed with the separately-fed concrete for use. The amount of conventional quick-setting admixture used is at most 10% by weight or less, usually 5 to 10% by weight, based on 100 parts by weight of cement.
On the order, even if the time of the concrete number of m ³ ~ Number 10 m ³ in spraying is used, since the capacity of the general-purpose quick-addition device is about 150 kg, suddenly quick-addition device previously Once the binder was full, there was no need to add more in one spray. However, when using a quick-setting admixture containing calcium aluminate and gypsum, which has high strength and little decrease in strength, 10 to 20% by weight of cement is used.
It is necessary to add a certain amount, and especially in a large-section tunnel with a large amount of spraying, the amount of quick-setting agent used at one time becomes extremely large, so the quick-setting agent in the quick-setting agent addition device may become empty. In many cases, it is necessary to interrupt the spraying work each time and add a quick-setting admixture, or if the quick-setting admixture runs out during the work, concrete will fall and cause a serious obstacle such as danger. was there.

[0006] As described above, adding a large amount of the quick-setting admixture at the tunnel site where it is necessary to spray it as soon as possible to prevent the collapse after excavation poses a very serious problem in terms of safety and work efficiency. There was an extremely strong demand for the amount of the quick-setting agent added for spraying to be as small as possible, which was an urgent need. Further, if the amount of the quick-setting agent added is large, the mixing property with the concrete during use deteriorates, and as a result, the strength may partially vary or it may cause a drop, and further, the problem that a lot of dust is generated easily occurs. Also in this respect, high-strength spraying was practically impossible unless the amount of the quick-setting agent mixed during spraying was reduced.

Further, in the quick-setting agent containing calcium aluminate and gypsum, the surface of calcium aluminate premixed with gypsum contains water, moisture in air, and free SO ₃ content in gypsum. It seems that it will react, and as a result, the curing time at the start and end of spraying etc. will become longer as the days after mixing calcium aluminate and gypsum go up, and if it is remarkable, the curing time will be several days after mixing at the beginning of mixing. There was a problem that it became several times longer.
When the curing time of the sprayed material becomes long, for example, sprayed concrete in the top of the tunnel drops, does not adhere if there is spring water, and the rebound rate increases, resulting in safe and stable high strength. Spraying is impossible. As described above, it is practically impossible to spray a large-sized and large-capacity powder at the time of high-strength spraying, and the capital investment for the quick-setting admixture adding device is extremely large.

The present inventor has conducted various studies on the problems in imparting high strength to shotcrete, and as a result, obtained the knowledge that the above problems can be solved by spraying using a specific spraying material. Has been completed.

[0009]

Means for Solving the Problems That is, the present invention provides a cement mortar containing 100 parts of cement and 10 to 25 parts of gypsum as a main component, and a quick-setting agent containing calcium aluminate as a main component. Is a spray material, characterized in that the quick-setting agent is mainly composed of calcium aluminate and an aluminate alkali salt and / or alkali carbonate. And, in addition, a water reducing agent,
A spraying material comprising one or more admixtures selected from the group consisting of a setting retarder, a setting accelerator, and an ultrafine powder. This is a spraying method.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

As the cement used in the present invention, various portland cements such as normal, early strength, moderate heat, and super early strength, various mixed cements obtained by mixing blast furnace slag and fly ash with these portland cements, and commercially available Examples thereof include fine particle cement.

The gypsum used in the present invention is mixed with cement for the purpose of increasing the strength of shotcrete. Examples of the gypsum include anhydrous gypsum, hemi-water gypsum, and dihydrate gypsum, and one or more of these can be used. Of these, anhydrous gypsum is preferably used from the viewpoint of strength development. The particle size of gypsum may be such that it is usually used for cement or the like, for example, about 3,000 cm ² / g in terms of Blaine value, and it is more preferable to use fine powder. The amount of gypsum used is 100
Relative to the weight part, Ru 10-25 parts by der. If it is less than 10 parts by weight, it is difficult to promote the long-term strength development, and if it exceeds 25 parts by weight, initial setting is delayed, the adhesion to the ground is lowered, and there is a risk that the concrete expands for a long period of time and breaks.

The quick-setting agent used in the present invention is mainly composed of calcium aluminate. The calcium aluminate used in the present invention refers to one obtained by subjecting a mixture of CaO raw material, Al ₂ O ₃ raw material, etc. to a heat treatment such as firing in a kiln or melting in an electric furnace. , Is a quick-setting component that causes the setting of concrete in the early stage.
As a mineral component of calcium aluminate, CaO
, Al ₂ O ₃ is A, C ₃ A, C ₁₂ A ₇ , CA, and CA ₂
And the like, which are obtained by pulverizing a heat-treated product of calcium aluminate. Furthermore, as other mineral components, calcium aluminosilicate containing SiO ₂ , C ₁₂ A ₇
C ₁₁ A in which one CaO of the above is replaced by a halide such as CaF _2
7. Contains CaX ₂ (X is halogen such as fluorine) and SO ₃ components
Examples thereof include C ₄ A ₃ · SO ₃ , and calcium aluminate in which alkali metals such as sodium, potassium, and lithium are partially solid-dissolved, and one or more of these can be used. Among these, in terms of reaction activity, C ₁₂ A
Amorphous calcium aluminate obtained by quenching a heat-treated product corresponding to composition ₇ is preferable. The grain size of calcium aluminate is 3 in terms of Blaine value from the viewpoint of quick setting and initial strength development.
000 cm ² / g or more is preferable, and 4,000 cm ² / g or more is more preferable. The amount of calcium aluminate used is 100
The amount is preferably 1 to 20 parts by weight, more preferably 5 to 15 parts by weight, based on parts by weight. If it is less than 1 part by weight, it is difficult to cause initial setting, and if it exceeds 20 parts by weight, long-term strength development may be impaired.

In the present invention, it is possible to use calcium aluminate with alkali aluminate and / or alkali carbonate as a quick-setting agent.

The alkali aluminate salt used in the present invention promotes initial setting. Examples of the alkali aluminate include lithium aluminate, sodium aluminate, potassium aluminate and the like.
One kind or two or more kinds can be used. The amount of alkali aluminate used is preferably 1 to 50 parts by weight, more preferably 2 to 25 parts by weight, based on 100 parts by weight of calcium aluminate. If it is less than 1 part by weight, no effect is obtained, and if it exceeds 50 parts by weight, long-term strength development may be impaired.

The alkali carbonate used in the present invention improves the initial strength. Examples of the alkali carbonate include sodium carbonate, potassium carbonate, sodium bicarbonate, and the like, and one or more of these can be used. When alkaline carbonate is used in combination with alkaline aluminate, the quick binding property is further improved. The amount of alkali carbonate used is 0,0 based on 100 parts by weight of calcium aluminate.
5 to 200 parts by weight is preferable, and 1 to 50 parts by weight is more preferable. If it is less than 0.5 part by weight, it is not effective, and if it exceeds 200 parts by weight, long-term strength may decrease.

The amount of the quick-setting agent used is not particularly limited, but is preferably 1 to 20 parts by weight, more preferably 5 to 15 parts by weight, relative to 100 parts by weight of cement. If it is less than 1 part by weight, it is difficult to cause initial setting, and if it exceeds 20 parts by weight, long-term strength development may be impaired.

The cement mortar of the present invention is a mixture of at least cement and gypsum, and either dry cement mortar in a dry state in which water is not mixed or cement mortar mixed with water can be used. In the present invention,
The cement mortar can further be used in combination with one or more admixtures selected from the group consisting of water reducing agents, setting retarders, setting accelerators, and ultrafine powder.

The water reducing agent is used to improve the fluidity of the cement mortar, and either liquid or powdery one can be used. Examples of the water reducing agent include polyol derivatives, lignin sulfonates and their derivatives, and high-performance water reducing agents, and one or more of these can be used. Among these, it is preferable to use a high-performance water reducing agent from the viewpoint of imparting high strength expression. By using a high-performance water reducing agent, the spraying thickness can be reduced, the quick-setting force can be improved, the amount of quick-setting agent added and the amount of dust generated can be reduced, the rebound rate can be extremely reduced, and the spraying amount can be reduced. Can be efficiently enlarged.

Examples of the high-performance water reducing agent include formalin condensates of alkylallyl sulfonates, naphthalene sulfonates, and melamine sulfonates, and polycarboxylic acid type polymer compounds. One of these or Two or more kinds can be used, and either liquid or powder form can be used. Among these, the formalin condensate of naphthalene sulfonate, the formalin condensate of melamine sulfonate, and a combination thereof are preferable because the spraying amount can be efficiently improved. The amount of the high-performance 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 as a solid content. If it is less than 0.05 parts by weight, no effect is obtained, and if it exceeds 3 parts by weight, the strength development of cement mortar may be impaired.

Further, from the viewpoint of controlling the setting time of cement mortar, setting retarders such as organic acids and alkali carbonates, alkali metal hydroxides such as sodium hydroxide, slaked lime, and sulfates such as alum are also included. It is also possible to use a coagulation accelerator such as

Organic acids include gluconic acid, tartaric acid,
Examples thereof include citric acid, malic acid, lactic acid, and their sodium salts and potassium salts, and one or more of these can be used. The amount of organic acids used is 10
0.01 to 3 parts by weight is preferable with respect to 0 parts by weight, and 0.05 to 3 parts by weight is preferable.
2 parts by weight is more preferred. If it is less than 0.01 parts by weight, no effect is obtained, and if it exceeds 3 parts by weight, curing may be delayed too much, resulting in poor curing. Examples of the alkali carbonate include sodium carbonate, potassium carbonate, sodium bicarbonate, and the like, and one or more of these can be used.
The amount of alkali carbonate used 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 cement. If it is less than 0.01 parts by weight, no effect is obtained, and if it exceeds 10 parts by weight, curing may be delayed too much, resulting in poor curing.

From the viewpoint of increasing the setting retarding property, it is preferable to use a setting retarder in which an organic acid and an alkali carbonate are used in combination. In this case, the amount of alkali carbonate used is
100 to 100 parts by weight, preferably 10 to 1000 parts by weight, 50 to 7
00 parts by weight is more preferred. If it is less than 10 parts by weight, no effect is obtained, and if it exceeds 1000 parts by weight, curing may be delayed too much, resulting in poor curing. The amount of the set retarder, which is a combination of organic acid and 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 cement. If it is less than 0.01 parts by weight, no effect is obtained, and if it exceeds 10 parts by weight, curing may be delayed too much, resulting in poor curing.

The setting accelerator means an agent which promotes initial setting. Examples of the setting accelerator include alkali metal hydroxides such as sodium hydroxide, slaked lime, and sulfates such as alum, and one or more of these can be used. The amount of the setting accelerator used 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 cement. If it is less than 0.01 parts by weight, no effect is obtained, and if it exceeds 10 parts by weight, long-term strength development may not be improved.

The ultrafine powder used in the present invention has an average particle size of 10
When it is less than μm, it is possible to reduce the amount of cement, dust, and pumpability of concrete. Examples of the ultrafine powder include fine powder slag, fly ash, bentonite, kaolin, and silica fume, and one or more of these can be used. Among these, silica fume is preferable from the viewpoint of strength development. The amount of ultrafine powder used is 1 to 100 per 100 parts by weight of cement.
Part by weight is preferable, and 2 to 30 parts by weight is more preferable. If it is less than 1 part by weight, no effect is obtained, and if it exceeds 100 parts by weight, setting and curing may be delayed.

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 it is less than 35 parts by weight, the mixture cannot be sufficiently mixed, and if it exceeds 60 parts by weight, the strength is difficult to be obtained, and the amount of the quick-setting agent may be increased.

The aggregate such as coarse aggregate and fine aggregate used in the present invention preferably has a low water absorption rate and high aggregate strength, but is not particularly limited. Maximum size for coarse aggregate
It is preferably 20 mm or less, and more preferably 5 to 15 mm in maximum diameter in consideration of pumpability. The fine aggregate preferably has a maximum size of 5 mm or less, and examples thereof include river sand, mountain sand, lime sand, and silica sand.

In the present invention, the mixing method of each material is not particularly limited as long as cement and gypsum are mixed before mixing with the quick-setting agent. Examples thereof include a method of mixing a specific amount of gypsum with cement in advance, and a method of adding gypsum when kneading concrete. Furthermore, since the content of sulfur trioxide (SO ₃ ) in cement specified in JIS is about 3.0 to 4.5 wt% or less, the amount of gypsum that exceeds the JIS specified value when cement is manufactured at the cement manufacturing plant. A method of mixing the gypsum is also possible.

In the spraying method of the present invention, the required physical properties,
From economic and workability, spraying work can be performed as dry cement mortar containing cement, cement mortar containing cement and water, or paste or concrete of these, and either dry spraying method or wet spraying method can be used. Can be used. As a dry spraying method, cement, gypsum, if necessary, an aggregate and a quick-setting admixture are mixed, pneumatically fed, and in the middle, for example, water is added from one side of the Y-shaped pipe and sprayed in a wet state. Methods and the like. Wet spraying methods include cement, gypsum, and if necessary aggregate,
And water are mixed and kneaded, pneumatically fed, and in the middle, for example, a quick-setting agent is added from one of the Y-shaped tubes and sprayed. In the case of the wet spraying method, water is added to the cement mortar side.

The water reducing agent, setting retarder, setting accelerator, and ultrafine powder can be mixed on either side of the cement mortar side or the quick setting agent side, and may be used on only one side or on both sides. Although it is good, it is preferable to add it to the cement mortar side from the viewpoint of improving the strength, preventing rebound, and controlling the setting. There is no problem if finally the quick-setting shotcrete in which these materials are mixed is shot.

In the spraying method of the present invention, conventionally used spraying equipment can be used. Normally, the spray pressure is 2-5 kg / c
m ² , spraying speed is 4 to ²⁰ m ³ / h. The spraying equipment is not particularly limited as long as the spraying is sufficiently performed.For example, the product name “Aliver 280” of Alibar Co. is used for the concrete pressure-feeding, and the quick-mixing agent pressure-feeding device “” is used for the pressure-fastening agent pressure-feeding. Natm Cleat "can be used.

[0032]

EXAMPLES The present invention will be described in detail below based on examples.

Example 1 Cement 400 kg / m ³ , fine aggregate 1,055 kg / m ³ , coarse aggregate 713 kg /
m ^3, water 200 kg / m ^3, and was sprayed concrete by mixing gypsum in an amount shown in Table 1. This sprayed concrete was pressure-fed using a spraying machine "Ariva-280", and from one side of a Y-shaped tube provided on the way, a quick-setting admixture machine "Denka Tom Cleat" was used to cover 100 parts by weight of cement. A quick-setting shotcrete was prepared by mixing a quick-setting agent consisting of calcium aluminate in the amount shown in 1 above. This quick-setting sprayed concrete was sprayed onto the mold under the condition of 4 m ³ / hr, and the compressive strength of each material age was measured. The results are also shown in Table 1.

<Materials used> Cement: Ordinary Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd., specific gravity 3.16 Gypsum: Commercial anhydrous gypsum, Blaine value 5,400 cm ² / g Fine aggregate: sand, Niigata prefecture river sand, surface water ratio 5 %, Specific gravity 2.
61 Coarse aggregate: Crushed stone, Maximum size 15 mm, Surface dry condition, Specific gravity 2.65 Water: Tap water, 20 ° C Calcium aluminate: C ₁₂ A ₇ Amorphous calcium aluminate obtained by quenching heat-treated product, Blaine value 5,900 cm ² / g, specific gravity 2.90

<Measurement method> Compressive strength: prepared sprayed concrete, width 25 cm x length
It was sprayed on a 25 cm pullout formwork and a formwork of width 50 cm x length 50 cm x thickness 20 cm. The material age of 3 hours or less was measured using a test piece of a pullout form. The pins are covered with quick-setting shotcrete from the surface of the pull-out form, and the pins are pulled out from the back side of the form, and the pull-out strength at that time is calculated. The value of (compressive strength) = (pull-out strength) x 4 / (specimen surface area) The compressive strength was calculated from the formula. 50 cm width x length after 1 day of age
50 cm x 20 cm thick formwork 5 cm diameter x 10 cm length
The specimen was measured with a 20 ton pressure machine to determine the compressive strength.

[0036]

[Table 1] H is time, D is day. The gypsum and quick-setting agent are parts by weight relative to 100 parts by weight of cement. *: Core cannot be collected due to insufficient strength

Example 2 100 parts by weight of cement and 15 parts by weight of gypsum were mixed to obtain sprayed concrete, and 100 parts by weight of calcium aluminate was mixed with the amounts of alkali aluminate salt and alkali carbonate shown in Table 2. The same procedure as in Example 1 was carried out except that 10 parts by weight of the quick-setting admixture was mixed with 100 parts by weight of cement to obtain quick-setting concrete. The results are also shown in Table 2.

<Material used> Alkaline aluminate: Commercial sodium aluminate Alkali carbonate: Commercial sodium carbonate

[0039]

[Table 2]

As is clear from the table, it was confirmed that the initial strength was increased in proportion to the added amount and good strength development was exhibited. Also, the setting was accelerated in proportion to the added amount. The combination of alkali aluminate and alkali carbonate had a short quick setting time, and concrete was not leaked out, so it was also effective for spring locations. For comparison, a cement binder containing 100 parts by weight of calcium aluminate, 100 parts by weight of gypsum, and 10 parts by weight of sodium aluminate was mixed with cement 40 parts by weight.
0 kg / m ^3, fine aggregates 1,055kg / m ^3, coarse aggregate 713kg / m ^3, and water 20
It was added to concrete consisting of 0 kg / m ³ by an air pressure type quick-setting admixture adding device and sprayed. As a result, in order to obtain strength development similar to that of Experiment No. 2-6, twice as much as Experiment No. 2-6, 20
More than part by weight was required. In addition, since there is a lot of dust on the work side, it is necessary to interrupt the spraying and replenish the quick-setting agent adding device with the quick-setting agent, and the hose is often clogged during spraying, and the work cannot be performed.

Example 3 100 parts by weight of cement and 10 parts by weight of gypsum were mixed to obtain sprayed concrete, and a quick-setting admixture prepared by mixing 100 parts by weight of calcium aluminate and 10 parts by weight of alkali aluminate salt,
Example 1 was repeated except that the amount shown in Table 3 was used for 100 parts by weight of cement to obtain quick-setting shotcrete. The results are also shown in Table 3.

[0042]

[Table 3]

Example 4 15 parts by weight of gypsum was mixed with 100 parts by weight of cement.
Dry concrete was mixed as in Example 1 except that
Then, they were carried into the spraying machine by a belt conveyor. Quick-setting agent
Is 100 parts by weight of calcium aluminate and aluminate
On a belt conveyor, mix 10 parts by weight of Lucari salt.
For 100 parts by weight of cement in dry concrete
Adjust to 10 parts by weight and add to dry concrete.
Was added. Spraying dry concrete with quick-setting admixture
Air is sent from the machine, and water is cemented 100 weights by Y-tube.
In addition to 50 parts by weight, dry spraying
went. As a result, spraying without trouble such as blockage of piping
Construction can be carried out, and the compressive strength of the sprayed material at that time
The degree is 4.1 N / mm after 1 hour², 28 days 58.5N / mm
²Met.

For comparison, dry cement not mixed with gypsum was mixed with 100 parts by weight of calcium aluminate as a quick-setting agent, 100 parts by weight of anhydrous gypsum, and 10 parts by weight of an aluminate alkali salt to obtain 100 parts of cement.
Dry spraying was carried out in the same manner except that 20 parts by weight was added to the parts by weight. As a result, a lot of dust is generated,
A short time after the start of spraying, the material was clogged in the pressure-feeding pipe, and the work could not be performed sufficiently.

Example 5 100 parts by weight of cement, 10 parts by weight of gypsum, and the amount of the high-performance water reducing agent α shown in Table 4 were mixed to obtain sprayed concrete, and 100 parts by weight of calcium aluminate and 10 parts by weight of alkali aluminate salt were mixed. The same procedure as in Example 1 was carried out except that 10 parts by weight of the quick-setting admixture obtained by mixing 10 parts by weight with 100 parts by weight of cement was mixed to obtain a quick-setting shotcrete. The results are shown in Table 4.
Also described in.

<Materials used> Water-reducing agent α: Commercially available high-performance water-reducing agent, main component sodium naphthalene sulfonate

[0047]

[Table 4]

Example 6 10 parts by weight of gypsum and 100 parts by weight of cement are shown in Table 5.
The amount of setting retarder and setting accelerator shown in Fig. 2 is mixed to make sprayed concrete, and 7 parts by weight of the quick-setting admixture containing 100 parts by weight of calcium aluminate and 10 parts by weight of alkali aluminate is added to 100 parts by weight of cement. The same procedure as in Example 1 was carried out except that the parts were mixed. The results are also shown in Table 5.

<Materials used> Set retarder A: organic acid, citric acid, reagent set retarder B: alkali carbonate, sodium carbonate, reagent set retarder C: alkali carbonate, sodium bicarbonate, reagent set accelerator: Slaked lime, commercial product

[0050]

[Table 5]

Example 7 100 parts by weight of cement, 10 parts by weight of gypsum, 1 part by weight of water reducing agent B, and ultrafine powder in the amounts shown in Table 6 were mixed to obtain sprayed concrete, and 100 parts by weight of calcium aluminate and alkali aluminate salt. Spraying was performed in the same manner as in Example 1 except that 10 parts by weight of the quick setting agent mixed with 10 parts by weight was mixed with 100 parts by weight of cement to obtain quick setting shotcrete. The results are also shown in Table 6.

<Materials used> Water reducing agent B: Commercially available high-performance water reducing agent, main component polycarboxylic acid sodium salt ultrafine powder a: ground blast furnace slag crushed and classified product, average particle size 10 μm or less ultrafine powder b: silica fume, average particle size 10 μm The following ultrafine powder c: metakaolin, average particle size 10 μm or less

<Measurement method> Rebound rate: Quick-setting sprayed concrete was sprayed at a spraying speed of 4 m ³ / h for 30 minutes on a simulated tunnel of 3.5 m in height and 2.5 m in width. After spraying, measure the amount of sprayed concrete that did not adhere and dropped, (rebound rate) = (weight of sprayed concrete that did not adhere to the simulated tunnel during spraying) / (used for spraying) The weight of sprayed concrete) x 100 (%).

[0054]

[Table 6]

As is clear from the table, it was confirmed that the rebound rate was reduced by using the ultrafine powder.

Example 8 100 parts by weight of cement, 10 parts by weight of gypsum, 10 parts by weight of ultrafine powder b, 1 part by weight of setting retarder A, 2 parts by weight of setting retarder B,
And Example 7 except that 0.5 part by weight of a setting accelerator was mixed. As a result, shotcrete with very little dust and a small rebound rate of 3.6% was obtained. Was sprayed the quick-setting property Shotcrete, age of 1 hour strength 3.0 N / mm ^2, age of 28 days strength of 59.5N / mm ^2, and the initial and long-term both very high strength high performance spray A concrete was obtained.

Example 9 100 parts by weight of cement, 10 parts by weight of gypsum, 1 part by weight of water-reducing agent B, 10 parts by weight of ultrafine powder d, and an amount of a set retarder and a set accelerator shown in Table 7 were mixed to obtain sprayed concrete, It carried out like Example 8 except having sprayed at a spraying rate of 2.5 m ³ / hr. The results are also shown in Table 7.

[0058]

[Table 7]

As is apparent from the table, the water reducing agent, ultrafine powder,
When a setting retarder and a setting accelerator are used together, less dust and less rebound. Further, spraying excellent in strength development in the initial and long term can be carried out.

Example 10 The unit amount of cement was as shown in Table 8 and the amount of water used was as shown in Table 8 with respect to 100 parts by weight of cement.
100 parts by weight of gypsum and 10 parts by weight of gypsum are mixed to form shotcrete, and 10 parts by weight of cement is used for 100 parts by weight of cement with 100 parts by weight of calcium aluminate and 10 parts by weight of alkali aluminate. The same procedure as in Example 1 was carried out except that a quick-setting shotcrete was used. For shotcrete, the slump immediately after kneading was measured. The results are also shown in Table 8. <Measurement method> Slump: Measured according to JIS A 1101.

[0061]

[Table 8]

Example 11 Gypsum with a Blaine value of 5,000 cm ² / g and calcium aluminate were put in separate bags and stored at a temperature of 20 ° C. and a humidity of 60%, and the gypsum was mixed with cement at the time of use. , Cement / fine aggregate ratio = 1/3, water consumption is 100 cement
A quick-setting mortar was prepared by mixing 60 parts by weight with respect to parts by weight of mortar and mixing it with calcium aluminate. Separately, save a mixture of gypsum and calcium aluminate with a Blaine value of 5,000 cm ² / g,
A mortar having a cement / fine aggregate ratio of ⅓ at a water content of 60 parts by weight relative to 100 parts by weight of cement was prepared, and a quick-setting mortar was prepared by mixing the mixture with this mortar. Mortar setting tests were carried out to compare the storage properties of these quick-setting mortars. The total amount of calcium aluminate and gypsum used is cement.
15 parts by weight based on 100 parts by weight. The results are shown in Table 9.

<Measurement method> Condensation test: Measured at 20 ° C. according to the Proctor resistance test (ASTM C 403).

[0064]

[Table 9]

As is clear from the table, the preservability varies greatly depending on the mixing method of gypsum and calcium aluminate. The more gypsum, that is, the easier it is to obtain high strength, the larger the starting point will be when stored and the troubles will increase. There was a strong fear of becoming the cause.

Comparative Example The same procedure as in Example 11 was carried out except that gypsum and calcium aluminate were mixed in advance and the mortar setting test was carried out in five lots having different mixing dates. The results are shown in Table 10. If gypsum and calcium aluminate are mixed in advance, the starting time and closing time of the mixture of gypsum and calcium aluminate may be extremely long in a few days depending on the mixing day, and stable physical properties may not be obtained. , Therefore the mixture could not be used as a product.

[0067]

[Table 10]

[0068]

EFFECTS OF THE INVENTION By using the spraying material of the present invention, the strength development in the initial and long-term is better than that of the conventionally used spraying materials of calcium aluminate type or calcium aluminate and alkali aluminate type. Becomes Therefore, the spraying thickness can be made thinner than before, the spraying time can be shortened, and the spraying amount can also be reduced, which is advantageous in that it is economical. Further, the amount of the quick-setting agent added on site can be reduced to about half, and the amount of the quick-setting agent added at the site can be reduced, so that it is not necessary to interrupt the spraying work and the amount of dust generated at the time of spraying can be reduced. Further, compared with the case of using a quick-setting agent in which gypsum and calcium aluminate were mixed in advance, the preservability was significantly different, and it was impossible to put into practical use unless it was the product of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI // C04B 103: 12 C04B 103: 12 (72) Inventor Kenkichi Hirano 2209 Aomi, Aomi-cho, Nishikubiki-gun, Niigata Prefecture Denki Kagaku Kogyo Co., Ltd. Aomi Plant (72) Inventor Isamu Terajima 2209 Aomi, Aomi Town, Nishikubiki-gun, Niigata Aomi Plant, Denki Kagaku Kogyo Co., Ltd. (56) Reference JP-A-3-122040 (JP, A) JP-A-63-112448 (JP, A) JP-A-8-310850 (JP, A) JP-A-59-30740 (JP, A) JP-B 7-25577 (JP, B2) "Concrete Handbook", Japan, J-Hong Kong Japan Concrete Engineering Society, 1976, 1st edition, 152, 153 (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 22/00-22/16 C04B 28/02-28/10 C04B 7 / 04

Claims (4)

(57) [Claims] 1. A spray comprising a cement mortar obtained by mixing 100 parts of cement and 10 to 25 parts of gypsum as a main component, and a quick-setting agent containing calcium aluminate as a main component. material. 2. The quick-setting agent is calcium aluminate,
The spray material according to claim 1, which comprises an aluminate alkali salt and / or an alkali carbonate as a main component. 3. The composition further comprises one or more admixtures selected from the group consisting of a water reducing agent, a setting retarder, a setting accelerator, and an ultrafine powder. Or the spray material according to 2. 4. A spraying method using the spraying material according to any one of claims 1 to 3.