JP5701546B2 - Spraying material and spraying method using the same - Google Patents

Description

  The present invention relates to, for example, a spraying material sprayed onto a ground surface exposed in a tunnel or a slope such as a road, a railway, and a waterway, and a spraying method using the same.

In order to prevent the collapse of exposed ground such as tunnel excavation, spraying method of quick setting concrete in which quick setting agent is mixed with concrete is performed. This method usually involves preparing sprayed concrete at a cement, aggregate and water metering and mixing plant installed at the excavation site, transporting it with an agitator car, pumping it with a concrete pump, and using a confluence pipe installed in the middle. This is a method of mixing with a rapid setting agent fed from the other side and spraying it to the ground surface as a quick setting sprayed concrete until a predetermined thickness is reached.
The quick-setting admixture, mixtures of calcium aluminate and an alkali carbonate, mixtures of calcium aluminate and 3CaO · SiO _2, calcium aluminate, mixture of alkali metal aluminate, and alkali carbonate, and the like, as well as, A mixture of a calcining van, aluminate, carbonate, slaked lime, sodium aluminate, sodium carbonate and the like are known (Patent Documents 1, 2, 3, 4, 5).
The quick setting agent is mixed with cement concrete and sprayed on the natural ground surface. The method of adding the quick setting agent is usually a method in which the amount of dust is increased due to powder mixing by pneumatic transportation. For this reason, the working environment may be deteriorated, and it is necessary to wear protective glasses, a dust mask, or the like when spraying, and a construction method with less dust is required.
As a method of generating less dust, a method is proposed in which a quick setting agent is slurried and added to cement concrete, and then an alkali metal aluminate solution is separately pumped, mixed, and sprayed. (Patent Document 6). Since this method uses a highly alkaline liquid, it is difficult to handle, and when spraying, protective glasses or gloves are required, and there is a problem that workability is reduced. On the other hand, the quick setting construction method which improves a working environment by making a quick setting agent into slurry and mix | blending alums with cement concrete is proposed (patent document 7). In recent years, there has been proposed a quick setting method that improves workability and dust reduction effect and improves quick setting in terms of shortening the work period (Patent Document 8).

However, there is a need for a quick alkalinity, preferably a neutral or weak acid quick setting agent, having a lower pH value than a quick setting agent in which alkali metal aluminate or alkali metal carbonate is mixed with calcium aluminate. In order to solve this problem, the liquid accelerating agent is mainly composed of a basic aluminum salt or an organic carboxylic acid (Patent Document 9), or mainly composed of aluminum sulfate or an alkanolamine (Patent Document 10). ), And a basic aqueous solution of aluminum, lithium silicate, lithium aluminate (Patent Document 11), and the like. On the other hand, this liquid quick-setting agent is difficult to obtain the initial strength, and there is a risk of peeling off when it is blown thickly in a tunnel tunnel as compared with conventional quick setting agents mainly composed of calcium aluminate. (Patent Documents 12 and 13).
Therefore, one or more selected from the group of inorganic liquid compounds consisting of an acidic liquid accelerator mainly composed of aluminum or sulfur and powdered aluminum sulfate, sulfate, aluminate, or hydroxide are added. A spraying material characterized by this has been developed (Patent Document 14). Since powder is highly reactive with cement and cannot be mixed when preparing cement concrete, it is necessary to add an acid liquid quick-setting agent and powder immediately before spraying cement concrete, and there are two machines. Since it is necessary, the construction may be complicated.

Japanese Patent Publication No. 60-4149 Japanese Patent Laid-Open No. 64-051351 Japanese Examined Patent Publication No. 56-27457 JP-A-61-026538 JP 63-2105050 A Japanese Patent Laid-Open No. 5-139804 JP-A-5-097491 JP 2003-81664 A JP-T-2001-509124 Japanese Patent Laid-Open No. 10-087358 JP 2001-130935 A JP 2002-047048 A JP 2003-246659 A JP 2007-55831 A

  The present invention improves the quick setting property of the acidic liquid quick setting agent and has a high strength promoting effect in long-term strength, and it is possible to pre-add the quick setting material to cement concrete. Provide the spraying method.

The present invention provides: (1) calcium aluminates containing CaO · _Al 2 _{O 3,} and also contains calcium alumino ferrites including _{6CaO · 2Al 2 O 3 · Fe} 2 O 3, calcium aluminates Is an acidic liquid or slurry containing sulphate, sulfur, aluminum, and lithium in cement concrete containing an admixture with a mass mixing ratio of 1: 1 to 2 and calcium aluminoferrite (2) A spraying method characterized by pumping cement concrete containing the admixture of (1) and mixing and mixing with the rapid setting agent of (1). .

  By adopting the spraying material of the present invention and the spraying method using the same, it becomes possible to blend the quick setting material into cement concrete in advance, and the equipment for blending powder becomes unnecessary, and the tunnel In order to suppress the generation of dust generated by spraying operations, etc., workability has been improved, and even in situations where spring water and natural ground surface have deteriorated, high quick setting is obtained, and long-term strength expression is achieved. There is an effect that can be applied to a place where sex is required.

  Unless otherwise specified, parts and% in the present invention are shown on a mass basis.

The calcium aluminates used in the present invention are obtained by mixing a raw material containing calcia, a raw material containing alumina, etc., and performing a heat treatment such as firing in a kiln or melting in an electric furnace, and CaO and It is a general term for substances having hydration activity, mainly composed of Al ₂ O ₃ . Some of CaO and Al ₂ O ₃ are alkali metal oxides, alkaline earth metal oxides, silicon oxides, titanium oxides, iron oxides, alkali metal halides, alkaline earth metal halides, alkali metal sulfates, and These are substances in which a small amount of these are dissolved in a compound substituted with alkaline earth metal sulfate or the like, or in which CaO and Al ₂ O ₃ are the main components.
As mineral forms, compositions of 12CaO · 7Al ₂ O ₃ (hereinafter referred to as C ₁₂ A ₇ ), 3CaO · Al ₂ O ₃ (hereinafter referred to as C ₃ A), and CaO · Al ₂ O ₃ (hereinafter referred to as CA). This corresponds to a heat-treated product having a CaO / Al ₂ O ₃ molar ratio of 1.20 to 2.60. The particle size of the calcium aluminates is in terms of quick-setting property and the initial strength development, Blaine specific surface area (hereinafter, referred to as Blaine) 3,000 cm ² / g or more, more preferably at least 5,000 cm ² / g . If it is less than 3,000 cm < ² > / g, initial strength development property may fall.

The calcium aluminoferrites used in the present invention are mixed with a raw material containing calcia, a raw material containing alumina, a raw material containing ferrite, etc., and subjected to heat treatment such as firing in a kiln or melting in an electric furnace. It is a generic term for substances having hydration activity, which are obtained by using CaO, Al ₂ O ₃ and Fe ₂ O ₃ as main components. CaO, Al ₂ O ₃ , Fe ₂ O ₃ are partly alkali metal oxide, alkaline earth metal oxide, silicon oxide, titanium oxide, alkali metal halide, alkaline earth metal halide, alkali metal sulfate , And a compound substituted with alkaline earth metal sulfate or the like, or a substance mainly composed of CaO, Al ₂ O ₃ and Fe ₂ O ₃ , which is a substance which is dissolved in a small amount.
As the mineral forms, for _{example, 4CaO · Al 2 O 3 ·} Fe 2 O 3 ( _{hereinafter, C} 4 as AF) corresponds to the composition _{and, 6CaO · 2Al 2 O 3 ·} Fe 2 O 3 ( _{hereinafter, C} 6 A _This corresponds to the composition of ₂ F).

  By mixing calcium aluminoferrites with calcium aluminate, it has the function of suppressing the rapid hydration reaction of calcium aluminates. This makes it possible to prevent a sudden slump down associated with.

  The admixture used in the present invention preferably has a mass mixing ratio of calcium aluminates and calcium aluminoferrites of 1: 1 to 3, more preferably 1: 2. If the amount of calcium aluminate is increased more than the above conditions, the workability may be remarkably lowered without the cement concrete being kneaded. If the amount of calcium aluminates is less than the above conditions, the initial strength is expressed. May decrease. When the amount of calcium aluminoferrites increases beyond the above conditions, the initial strength development may be reduced.

  The amount of the admixture used in the present invention is preferably 2 to 10 parts, more preferably 4 to 8 parts, relative to 100 parts of cement. If the amount of admixture used is small, excellent quick setting properties and strength development may not be exhibited, and if the amount of admixture used is large, long-term strength development may be reduced.

  The admixture used in the present invention includes, in addition to calcium aluminate and calcium aluminoferrite, for example, alkali metal sulfate, alkali metal carbonate, alkaline earth metal sulfate, alkaline earth metal carbonate, alkali metal Aluminates, retarders, water reducing agents, fibers, foaming agents, antifoaming agents and the like can be contained.

  The acidic liquid quenching agent sulfur feed used in the present invention is not particularly limited, and in addition to sulfur in the elemental state such as sulfur and sulfur white, sulfide, sulfuric acid or sulfate, sulfurous acid or Examples thereof include sulfites, thiosulfuric acid or thiosulfates, and organic sulfur compounds, and one or more of them can be used. Among these, sulfuric acid or sulfate is preferable from the viewpoints of high solubility in water, low production costs, and excellent quick setting properties.

  The feedstock of the aluminum of the acidic liquid accelerator used in the present invention is not particularly limited, and includes amorphous or crystalline aluminum hydroxide, aluminum sulfate, aluminate and other containing aluminum. Inorganic aluminum compounds, organic aluminum compounds, and compounds such as aluminum complexes can be mentioned, and one or more of these can be used. Of these, the use of aluminum sulfate, which is also a sulfur feedstock, is preferred.

  The acidic liquid quenching agent lithium used in the present invention is not particularly limited, and examples thereof include inorganic lithium compounds and organic lithium compounds containing lithium, one or more of these. Can be used. Among these, the use of lithium sulfate monohydrate is preferable from the viewpoints of strength development, solubility, and precipitation prevention at low temperatures.

  The acidic liquid quick setting agent of the present invention preferably has a pH of 6 or less. If the pH is high, the stability of the acidic liquid may be impaired.

  2-11 parts are preferable with respect to 100 parts of cement, and, as for the usage-amount of the acidic liquid quick setting agent of this invention, 4-9 parts are more preferable. If the amount of the acidic liquid quick-setting agent is small, excellent quick-setting properties may not be exhibited. If the amount of the acidic liquid quick-setting agent is large, long-term strength development may be deteriorated.

  The acidic liquid quick setting agent of the present invention can be improved in quick setting property by heating at a temperature in the range of 10 to 40 ° C. and mixing with cement concrete.

  The concentration of the solid content of the acidic liquid of the present invention is preferably 20 to 60%, and more preferably 25 to 50%. If the solid content is low, an excellent quick setting property may not be obtained. If the solid content is high, the viscosity of the liquid is high, and the pumpability of the pump may deteriorate.

  The cement used in the present invention is not particularly limited, and various ordinary portland cements such as early strength, very early strength, moderate heat, and low heat, and blast furnace slag, fly ash, and limestone fine powder to these Portland cements. , And environmentally friendly cement (eco-cement) manufactured using municipal waste incineration ash or sewage sludge incineration ash as raw materials. These can also be used in the form of fine powder. The ratio of the mixture to the cement in the mixed cement is not particularly limited, and a mixture obtained by mixing these admixtures more than expected by JIS can be used.

  The cement concrete used in the present invention contains cement and aggregate. Aggregates with low water absorption and high aggregate strength are preferred. The maximum size of the aggregate is not particularly limited as long as it can be sprayed. As fine aggregate, river sand, mountain sand, sea sand, lime sand, quartz sand, etc. can be used, and as coarse aggregate, river gravel, mountain gravel, lime gravel, etc. can be used, crushed sand, It is also possible to use crushed stone.

  As the spraying method using the spraying material of the present invention, various spraying methods according to the required physical properties, economy, workability and the like are possible. Above all, as a typical spraying method using an acidic liquid quick-setting agent, cement concrete is transported from one side by a concrete pump, and from the other, an acidic liquid quick-setting agent is pumped and immediately before spraying, cement concrete. And the acidic liquid quick setting agent are combined and mixed with compressed air, and the amount of compressed air used at the time of spraying is small, which is preferable in terms of dust countermeasures in the tunnel tunnel, workability, and performance of the spraying material.

"Experiment 1"
800 g of cement, 2000 g of fine aggregate, 480 g of water, 6 parts of an admixture of the types and mixing ratios (mass ratio) shown in Table 1 are mixed with 100 parts of cement to prepare a mortar, and 30 minutes after the mortar is finished Every mortar flow was measured for up to 90 minutes. For comparison, a base mortar to which no admixture was added was also tested in the same manner.

<Materials used>
Calcium aluminates A: C ₃ A composition, crystalline, brane value 4,600 cm ² / g
Calcium aluminates B: CA composition, crystalline, brane value 4,500 cm ² / g
Calcium aluminoferrites a: C ₄ AF composition, crystalline, chemical component Al ₂ O ₃ : 19.8%, CaO: 47.3%, Fe ₂ O ₃ : 32.9%, Blaine value 4,300 cm ² / g
Calcium aluminoferrites b: C ₆ A ₂ F composition, crystalline, chemical component Al ₂ O ₃ : 28.7%, CaO: 47.3%, Fe ₂ O ₃ : 23.9%, Blaine value 4,800 cm ² / g
Cement: Ordinary Portland cement, commercial product, Blaine value 3,200 cm ² / g, specific gravity 3.16
Fine aggregate: Himekawa water system river sand, Itoigawa City, Niigata Prefecture, surface dry state, specific gravity 2.62, F.R. M (rough grain ratio): 2.85

<Production raw materials>
CaO raw material: quick lime, CaO 98%
Al ₂ O ₃ raw material: Bauxite, Al ₂ O ₃ 84.54%
Fe ₂ O ₃ raw material: Reagent, Fe ₂ O ₃ 99.9%

<Methods for producing calcium aluminates and calcium aluminoferrites>
Production raw materials were mixed, pulverized, melted in an electric furnace, slowly cooled, and pulverized to produce various clinker.

From the results in Table 1, when calcium aluminates A and B were blended alone into mortar, no results were obtained. Calcium aluminate A has stronger activity on cement and is harder to knead, but by using calcium aluminoferrites, the mortar flow does not go down and the state is equivalent to that without admixture. became.
Experiment No. showing a value equivalent to that of the base mortar was picked up, and in the following Experimental Example 2, an acidic liquid quick-setting agent was added, and comparison tests such as initial setting and strength were performed.

"Experimental example 2"
The mortar picked up in Experimental Example 1 was mixed with 8 parts of an acidic liquid quick-setting agent to prepare a quick-setting mortar, and the setting test and strength development test were conducted after adding the acidic liquid quick-setting agent.

<Materials used>
Acidic liquid accelerator α: pH 2.5, 10% lithium sulfate monohydrate was dissolved in a 27% aqueous solution of aluminum sulfate.

<Measurement method>
Setting time: Measured according to the Japan Society of Civil Engineers standard "Quality standard for quick setting agent for shotcrete (JSCE D-102)" Compressive strength: Measured according to JIS R 5201.

From Table 2, it was confirmed that the calcium aluminate and the calcium alumina ferrite had better setting and compressive strength than the comparative example as long as the mixing ratio was in the range of 1: 1 to 3. It was confirmed that the initial strength tends to decrease as the mixing ratio of calcium aluminoferrites is increased.
Next, a mortar test was conducted using a comparative example in which lithium was not added to the acidic liquid quick-setting agent (Experimental Example 3).

"Experiment 3"
A mortar blend that was good in Experimental Example 2 was selected, and compared with a mortar in which the same admixture was added, and a quick mortar in which 8 parts of the liquid quickener β was mixed with cement.

<Materials used>
Acidic liquid accelerator β: pH 2.6, 27% aluminum sulfate aqueous solution

<Measurement method>
Setting time: Measured according to Japan Society of Civil Engineers standard "Quality standard for quick setting agent for shotcrete (JSCE D-102)" Compressive strength: Measured according to JIS R5201.

  From Table 3, when lithium is not added to the acidic liquid accelerating agent, both the start and end of setting are delayed, and the compressive strength is one day low, and lithium is essential for the acidic liquid accelerating agent of the present invention. I understand.

  According to the spraying material of the present invention and the spraying method using the same, it is possible to improve the physical properties of the current acidic liquid quick-setting agent, and the effect of promoting strength in the long-term strength is high, which can be added to cement concrete in advance. Therefore, it can be widely used in the civil engineering field.

Claims (2)

Calcium aluminate containing CaO · Al ₂ O ₃ and calcium aluminoferrite containing 6CaO · 2Al ₂ O ₃ · Fe ₂ O ₃ , mass mixing ratio of calcium aluminate and calcium aluminoferrite A spraying material obtained by combining and mixing cement concrete containing an admixture having a ratio of 1: 1 to 2 with an acidic liquid or slurry containing sulfuric acid such as sulfur, aluminum, and lithium. A spraying method characterized in that cement concrete containing the admixture according to claim 1 is pumped and mixed with the rapid setting agent according to claim 1.