JP2001206749A - Spraying material and construction method for spraying the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide spraying concrete having enhanced adhesive strength in the case of spraying and a lower rebounding rate, hardly causing alkali aggregate reaction and excellent in durability and to provide a construction method for spraying the spraying concrete. SOLUTION: As a spraying material, the one containing lithium bentonite, the one containing lithium bentonite and sulfate, the quick-setting one containing lithium bentonite, sulfate and a quick-setting agent and a cement composition containing the quick-setting one are exemplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spray material, a cement composition, and a cement composition for use in spraying quick-setting concrete onto an exposed ground surface in a tunnel such as a road, a railway, and a headrace. The present invention relates to a spraying method using the method. In the present invention, parts and percentages are based on mass unless otherwise specified. The concrete in the present invention is a general term for cement mortar and cement concrete.

[0002]

2. Description of the Related Art Conventionally, in order to prevent the collapse of an exposed ground such as a tunnel excavation, a quick-setting concrete spraying method in which a quick-setting agent is mixed with concrete has been used. JP 60-004149 A). In this spraying method, a concrete is usually prepared by mixing cement, aggregate, and water in a mixing and mixing plant installed at an excavation site, transported by an agitator truck, and pumped by a concrete pump, and This is a method of mixing with a quick-setting agent pumped from the other side and spraying it as a quick-setting concrete on the ground surface to a predetermined thickness. However, in this spraying method, the rebound (rebound) rate represented by [(amount of quick-setting concrete that has bounced down) / (amount of spraying of quick-setting concrete as a whole) × 100 (%)] is obtained. There was a problem that it was large and was not economically favorable.

In tunnel excavation and the like, primary lining using shotcrete is performed, and after the ground is stabilized in this state, secondary lining with ordinary cast-in-place concrete is performed inside. Have been done. On the other hand, in relatively hard ground with few cracks in the rock, etc., there is a case where the secondary lining concrete is not applied and the shotcrete is used as the permanent lining. Finished in this way is called single shell lining, which is widely used in Northern Europe and has been widely studied in Japan in recent years. Is required.

[0004] In general, shotcrete has a large unit cement amount and a large total alkali amount. In addition, since the sand / aggregate ratio (s / a) is large, deterioration of concrete due to alkali-aggregate reaction may be a problem. If a reactive aggregate that is not harmful in the alkali aggregate reaction is used, the concrete may crack and the durability may be impaired. In addition, when there is spring water from the ground, cracks reduce the watertightness of concrete,
Water may leak inside the tunnel. For this reason, there is a need for a spray material that suppresses the alkali-aggregate reaction.

The present inventor has made various studies to solve the above-mentioned problems, and as a result, obtained the knowledge that these problems can be solved by using a specific spraying material, and completed the present invention. Reached.

[0006]

That is, the present invention relates to a spraying material containing lithium bentonite and a spraying material further containing a sulfate, wherein the sulfate is aluminum sulfate. A quick-setting spray material comprising the spray material and a quick-setting agent,
A cement composition comprising cement and the spraying material or the quick-setting spraying material, wherein the spraying material, the quick-setting spraying material, or the spraying using the cement composition It is a construction method.

[0007]

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

By using the spraying material of the present invention, the viscosity of concrete is increased, the adhesion at the time of spraying is improved, the rebound rate can be reduced, and the alkali-aggregate reaction can be suppressed. .

[0009] The lithium bentonite (hereinafter referred to as Li bent) used in the present invention is not particularly limited, but is an aluminosilicate having a layered structure such as kaolinite, montmorillonite, and mica. It is a generic term for those containing lithium. Usually, the layer structure is formed by a combination of a two-dimensional sheet of oxygen tetrahedron centered on Si ⁴⁺ and an oxygen octahedron sheet centered on Al ³⁺ . This tetrahedral Si ⁴⁺
The layer charge generated by the substitution with Al ³⁺ makes it possible to carry ion-exchangeable lithium between the layers. The lithium ions carried between the layers are exchanged for Na ions and K ions by an ion exchange reaction. In the present invention, by using the Li vent, Na ions and K ions can be collected, and the amounts of sodium and potassium, which are the main factors of the alkali-aggregate reaction, can be reduced. The amount of lithium in the Li vent is not particularly limited, but is preferably 2.0 parts or more, more preferably 3.0 parts or more in terms of Li ₂ O per 100 parts of Li vent. If the amount is less than 2.0 parts, a sufficient effect of suppressing the alkali-aggregate reaction may not be obtained. The method for synthesizing Li vent is not particularly limited, but first, Na, K,
Alternatively, a method of synthesizing Ca bentonite and dispersing them in an aqueous solution of a lithium salt and ion-exchanging to Li vent, or a method of directly mixing lithium fluoride and the like at the time of synthesis and directly synthesizing the same. and so on. Although the specific surface area of the Li vent is not particularly limited, it is usually preferably 1 to 800 m ² / g as a BET specific surface area,
200 m ² / g is more preferred. If it is less than 1 m ² / g, a sufficient effect of suppressing the alkali-aggregate reaction may not be obtained,
If it exceeds 800 m ² / g, the viscosity of the concrete becomes too high, and pulsation may occur during pumping, making the spraying operation difficult. The amount of Li vent used is not particularly limited, but is preferably 1 to 20 parts with respect to 100 parts of cement,
2-10 parts are more preferred. If the amount is less than 1 part, a sufficient effect of suppressing the alkali-aggregate reaction may not be obtained. If the amount is more than 20 parts, the viscosity of the concrete may increase, and the pumping may be difficult.

The sulfate used in the present invention is used for further improving the adhesion of concrete and reducing the rebound rate. 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 these may be used alone or in combination of two or more. Is also possible. Among these, aluminum sulfate is more preferable from the viewpoint of improving adhesion. The amount of sulfate used is based on 100 parts of cement.
It is preferably 2 to 20 parts, more preferably 3 to 10 parts. If it is less than 2 parts, the effect of improving the adhesion may be small, and if it exceeds 20 parts, no further increase in the effect can be expected, and it may not be economically preferable.

The cement used in the present invention is not particularly limited, and various portland cements which are usually used, such as ordinary, fast-strength, ultra-high-strength, and low heat, and blast furnace slag, fly, etc. Ash, limestone fine powder, various mixed cements mixed with silica or the like, furthermore, expanded cement, colloid cement and the like can be used.

The quick-setting agent used in the present invention is not particularly limited, and alkali metal aluminates, alkali metal carbonates and silicates are used as inorganic salts, and calcium-setting agents are used as cement minerals. Aluminates, calcium sulfoaluminates and the like and triethanolamine and glycerin as organic substances can be used, and they can be used in any state of powder, slurry or liquid. Among them, calcium aluminates are preferred from the viewpoint of good setting properties and strength development. The amount of the quick setting agent is appropriately determined depending on the material used, but as the amount used is small, the inorganic salt is preferably about 3 to 5 parts with respect to 100 parts of cement. The most common ones are calcium aluminates of the cement mineral type.
About 15 parts is preferable. If the amount of the quick-setting agent is less than this, sufficient initial setting may not be obtained, and rebound may increase.If the amount of the quick-setting agent is used more than this, the long-term strength development is reduced, and economically May not be preferred.

In the present invention, it is preferable to use a fibrous material in order to improve the impact resistance and elasticity of the hardened cement concrete. As the fibrous material, any of inorganic and organic materials can be used. Examples of the inorganic fiber include glass fiber, carbon fiber, rock wool, asbestos, ceramic fiber, and metal fiber. Examples of the organic fiber include vinylon fiber, polyethylene fiber, polypropylene fiber, polyacryl fiber, and cellulose. Fiber, polyvinyl alcohol fiber, polyamide fiber, pulp, hemp, and the like. Among these, metal fibers and vinylon fibers are preferable from the viewpoint of economy and effects. The length of the fibrous material is preferably 50 mm or less, and more preferably 30 mm or less, from the viewpoint of pumpability and mixing properties. If it exceeds 50 mm, the pumping pipe may be blocked. The amount of fiber used is 10
0.5 to 3 parts by volume is preferable to 0 parts by volume. If the amount is less than 0.5 part by volume, the improvement of impact resistance and elasticity may not be observed, and if it exceeds 3 parts by volume, the fluidity of cement concrete may be significantly impaired.

In the present invention, in addition to the above materials, aggregates such as sand and gravel, AE agents, water reducing agents, AE water reducing agents, high performance water reducing agents, high performance AE water reducing agents, fluidizing agents, defoaming agents , Thickeners, rust inhibitors, anti-freezing agents, shrinkage reducing agents, polymer emulsions such as SBR and polyacrylate, coagulation regulators, swelling agents, ion exchangers such as zeolites, hydrotalcite, and hydrocalumite, inorganic One or two or more of phosphate, boric acid and the like can be used in combination as long as the object of the present invention is not substantially inhibited.

In the spraying material of the present invention, it is preferable that a spraying material containing a Li vent is previously mixed with concrete, and the quick-setting agent is mixed with the concrete by a mixing pipe in front of the spraying nozzle. When quick-setting spraying material is mixed with concrete, thickening and agglomeration occur rapidly and the pumpability decreases, so if it is added in other places,
Blockage and pulsation may occur. In the present invention, as a device for mixing cement, aggregate, water and the like, an existing stirring device can be used, for example, a tilting mixer, an omni mixer, a V-type mixer, a Henschel mixer, and a Nauta mixer can be used. It is.

As a method of mixing the quick-setting admixture, a method in which a powder quick-setting admixture is pneumatically fed and mixed with concrete, or a method in which water is added to the quick-setting admixture to form a slurry to form a quick-setting admixture slurry, and is mixed and mixed with concrete. Any of these methods can be used, but a method of forming a slurry is preferred from the viewpoint of reducing the amount of dust. A common water pump can be used for adding water to the powdery quick-setting admixture, and a method of adding water together with compressed air is possible.
Furthermore, at the junction of the quick-setting agent and concrete, it is possible to adopt a structure in which the shape of the pipe and the inner wall are likely to be spiral or turbulent in order to improve the mixing property.

As the spraying method of the present invention, a dry spraying method or a wet spraying method can be used. The dry spray method is, for example, a method in which cement and aggregate are mixed and pneumatically fed, and water and a quick-setting agent are mixed and sprayed in a wet state, and the wet spray method is, for example, This is a method in which cement, aggregate, and water are mixed in advance to form concrete, which is then air-pneumatically fed, mixed and mixed with a quick-setting agent, and sprayed. Of these, the dry spraying method may increase the amount of dust, so it is preferable to use the wet spraying method. In the spraying method of the present invention, conventional spraying equipment and the like can be used. The spraying equipment is not particularly limited as long as spraying is sufficiently performed.
For concrete pumping, Ariba 28
"0", etc., and "Natom Cleat" (trade name, manufactured by Chiyoda Manufacturing Co., Ltd.) for pumping powder quick-setting agent, and "Ankomat Pump" (trade name, manufactured by Putzmeister Co., Ltd.) for pumping of quick-setting agent slurry It is possible. Further, the pressure of the compressed air for pumping the quick-setting agent is preferably about 0.01 to 0.3 MPa higher than the pressure for pumping the concrete so that the concrete does not enter the pumping tube of the quick-setting agent and block the inside of the tube. Further, the concrete pumping speed is preferably 4 to 20 m ³ / h.

[0018]

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

EXPERIMENTAL EXAMPLE 1 Natural kaolinite, magnesium nitrate, and lithium fluoride were used as main raw materials, and aluminum nitrate and silicon oxide were used as auxiliary raw materials to adjust the Si / Al molar ratio.
Li vents of various compositions with different ₂ O contents were synthesized. Natural kaolinite was calcined at 700 ° C. for 18 hours to form metakaolinite, and this was mixed with magnesium nitrate. When the Si / Al molar ratio of metakaolinite is 1, metakaolinite and magnesium nitrate are mixed at a molar ratio of 1: 3, and when the Si / Al molar ratio of metakaolinite exceeds 1, The mixture was adjusted by mixing aluminum nitrate and silicon oxide. These mixtures and lithium fluoride were mixed at a weight ratio of 1: 1 and fired in air at 800 ° C. for 24 hours. Unreacted lithium fluoride contained in the obtained calcined product was washed and removed with distilled water and then centrifuged. Further, in order to remove fluoride impurities, the substrate was washed with saturated boric acid, washed again with distilled water, centrifuged, and dried in a constant temperature chamber at 60 ° C. The synthesized lithium bentonite was identified by the powder X-ray diffraction method, and it was confirmed that the lithium bentonite exhibited a bottom-reflection-type diffraction pattern unique to the layered compound. Further, the amount of Li ₂ O was measured according to JIS R 5201. Water cement ratio 50%, fine aggregate ratio 60%, unit cement amount 450kg /
Using the formulation of m ^3, slump of the concrete was adjusted with water reducing agent to be comparable, and Li vent formulation shown in Table 1,
Concrete is produced, and a pumping speed of 15 m ³ / h and a pumping pressure of 0.4 MPa are applied by a sprayer “Aliver 280” manufactured by Aliver.
Pumped. Separately, a quick-setting agent pumping device "Natom Cleat" was used to pump the quick-setting agent to 100 parts of cement with respect to 100 parts of cement, and Y was installed just before spraying.
Mix it with shotcrete using a pipe, and spray 100 liters of it on the side wall of a simulated tunnel made of steel,
The rebound rate and the pulsation of the hose during shotcrete pumping were evaluated. The results are also shown in Table 1.

<Materials Used> Natural kaolinite: Kaolinite from Georgia Magnesium nitrate: Commercial reagent first grade Aluminum nitrate: Commercial reagent first grade Silicon oxide: Commercial reagent first grade Lithium fluoride: Commercial reagent first grade Cement: Commercial ordinary Portland cement , Specific gravity 3.16 Fine aggregate: Himekawa river sand, Niigata prefecture, specific gravity 2.62 Coarse aggregate: Himekawa river gravel, Niigata prefecture, specific gravity 2.64, maximum aggregate size 10mm Water: Tap water water reducing agent: Commercial high-performance AE water reducing agent, polycarbon Acid quick-setting agent: calcium aluminate, calcium aluminate / gypsum / aluminate mass ratio 100/100/14
A mixture consisting of However, calcium aluminate is 12
Corresponds to CaO · 7Al ₂ O ₃ composition, Blaine specific surface area 6,100cm ²
An amorphous gypsum was used, gypsum was type II anhydrous gypsum, a Blaine specific surface area was 5,100 cm ² / g, and aluminate was sodium aluminate.

<Measurement method> Rebound rate: (Amount of quick-setting sprayed concrete which bounces down) / (Quick-setting used for spraying) when quick-setting Shotcrete is sprayed on the side wall for 1 minute The total amount of shotcrete) x 100 (%). Pulsation: The pulsation of the hose during the pressurization of the shotcrete was visually evaluated. The case where the pumping hose did not pulsate was evaluated as ○, the case where pulsation occurred, the sprayed concrete was discharged without interruption, and the case where the pulsation was severe and the discharge was interrupted was evaluated as ×.

[0022]

[Table 1]

As is clear from Table 1, the addition of Li vent improves the adhesion at the time of spraying,
It is possible to reduce the rebound rate.

Experimental Example 2 The same procedure as in Experimental Example 1 was conducted except that 3 parts by weight of Li vent containing 5.0 parts of Li ₂ O was added to 100 parts of cement, and the sulfates shown in Table 2 were added. went. Table 2 shows the results.

<Materials Used> Sulfate a: Commercially pulverized aluminum sulfate, Blaine specific surface area 5,500 cm ² / g Sulfate b: Commercially pulverized sodium sulfate, Blaine specific surface area 5,200 cm ² / g Sulfate c: Commercially available Potassium sulfate ground product, Blaine specific surface area 5,200cm ² / g

[0026]

[Table 2]

As is clear from Table 2, the addition of a sulfate further improves the adhesion and can reduce the rebound rate.

Experimental Example 3 The same procedure as in Experimental Example 1 was carried out except that 3 parts of Li vent containing 5.0 parts of Li ₂ O was mixed with 100 parts of cement, and the quick-setting agent shown in Table 3 was mixed. went. The results are also shown in Table 3.

[0029]

[Table 3]

Experimental Example 4 Mortar was prepared by mixing 100 parts of cement, 200 parts of sand, 50 parts of water, 10 parts of quick-setting agent and Li vent shown in Table 4, and an alkali silica reactivity test was carried out. In preparing the specimen, each material was cooled in advance to facilitate molding, and was subjected to vibration molding using a table vibrator. The results are also shown in Table 4.

<Materials Used> Sand: Sanukite pyroxene andesite, according to JIS A 5308 Annex 7 (chemical method), the amount of dissolved silica was 750 mmol / l, and the decrease in alkali concentration was 200 mmol / l. thing.

<Measurement method> Alkali silica reactivity test (mortar bar method): JIS A
It was measured according to Annex 8 of 5308. Those showing an expansion of 0.1% or more were judged to be not harmless.

[0033]

[Table 4]

As apparent from Table 4, the mortar not using the spray material of the present invention had an expansion rate of more than 0.1% and was determined to be harmless. In this case, the content was less than 0.1%, which was judged to be harmless, indicating an effect of suppressing alkali-aggregate reaction.

[0035]

By using the spray material of the present invention, it is possible to improve the adhesion at the time of spraying and to reduce the rebound rate, suppress the alkali-aggregate reaction, and improve the durability. Excellent shotcrete is obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C04B 22:08 C04B 22:08 AB 22:12 22:12 22:06 22:06 A 24:04 24 : 04 22:14) 22:14) C 103: 12 103: 12 103: 30 103: 30 111: 20 111: 20

Claims (7)

[Claims] 1. A spray material containing lithium bentonite. 2. A spraying material containing lithium bentonite and a sulfate. 3. The spray material according to claim 2, wherein the sulfate is aluminum sulfate. 4. The method according to claim 1, further comprising a quick-setting agent.
4. The quick-setting spraying material according to any one of items 1 to 3. 5. A spraying method characterized by spraying using the spraying material or the quick-setting spraying material according to claim 1. Description: 6. A cement composition comprising a cement and the spraying material or the quick-setting spraying material according to claim 1. Description: 7. A spraying method comprising spraying using the cement composition according to claim 6.