JP7007059B2 - Thickening admixture for spraying and spraying materials using it - Google Patents

Description

The present invention relates to a thickening admixture for spraying and a spraying material using the same.

In the construction work of tunnels, underground spaces, slopes, etc., the spraying method using spraying materials such as sprayed concrete is used. The general spraying method is performed by pumping cement kneaded material such as base concrete and quick-setting admixture through separate transport pipes by different routes, merging and mixing during pumping, and then spraying from the tip of the spray nozzle to the ground. ing.

However, in general, the spraying method has problems such as a large amount of dust generated and a large amount of rebound of the sprayed mortar. To solve such a problem, for example, the spraying material of Patent Document 1 increases the viscosity of the mortar by blending a thickener with cement concrete, and suppresses dust generated during the spraying operation.

Japanese Unexamined Patent Publication No. 2001-240443

However, if a thickener is added to cement concrete to ensure sufficient viscosity, the initial strength development may decrease, and there is a problem that the sprayed part peels off before reaching the required spray thickness. rice field. Therefore, there is a demand for a new thickening admixture that replaces the conventional thickening agent.

An object of the present invention is to provide a thickening admixture for spraying, which reduces dust generated during spraying and improves the initial strength development, and a spraying material using the same.

As a result of diligent studies on the above problems, the present inventors can achieve both dust reduction and initial strength development by using an inorganic material having a specific brain specific surface area in combination with a thickener at a specific ratio. It has been found that a thickening admixture for spraying can be obtained.

That is, the present invention is, for example, as follows.
[1] A thickening admixture for spraying composed of a thickener and an inorganic material, wherein the brain specific surface area of the inorganic material is 4500 to 20000 cm ² / g, and the mass ratio of the inorganic material to the thickener ([inorganic material]. [Mass] / [Mass of thickener]) is 0.2 to 3.5, a thickening admixture for spraying.
[2] The thickening admixture for spraying according to [1], wherein the inorganic material is gypsum and / or fly ash.
[3] The thickening admixture for spraying according to [1] or [2], wherein the thickener is a cellulosic thickener.
[4] A spraying material containing cement, a thickening admixture for spraying according to any one of [1] to [3], and a quick-setting agent.

According to the present invention, it is possible to provide a thickening admixture for spraying that reduces dust generated during spraying and improves the initial strength development, and a spraying material using the same.

Hereinafter, embodiments of the present invention will be described in detail.

[Thickening admixture for spraying]
The thickening admixture for spraying of the present embodiment comprises a thickening agent and an inorganic material.

The type of the thickener according to the present embodiment is not particularly limited, and examples thereof include a cellulosic thickener, an acrylic thickener, and a guar gum thickener. As the thickener, a cellulosic thickener is preferable. Examples of the cellulosic thickener include carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. As the thickener, one type may be used alone, or two or more types may be used in combination.

The inorganic material according to the present embodiment is not particularly limited as long as it is an inorganic powder having a brain specific surface area within the range specified below. Examples of the inorganic material include calcium salts such as gypsum and calcium carbonate; and pozzolan substances such as fly ash, silica fume, and metakaolin. Examples of gypsum include anhydrous gypsum, dihydrate gypsum, and semi-hydrated gypsum. Anhydrous gypsum is preferable as the gypsum. Fly ash is classified into several types according to JIS A 6201: 2015, and JIS type I or JIS type II is preferable from the viewpoint of easily obtaining good viscosity and initial strength development. As the inorganic material, one kind may be used alone, or two or more kinds may be used in combination. Among the inorganic materials, gypsum and / or fly ash are preferable from the viewpoint that the viscosity of the mortar is further increased, the amount of dust generated at the time of spraying is likely to be reduced, and the initial strength development is easy to be ensured.

The brain specific surface area of the inorganic material is 4500 to 20000 cm ² / g. If the brain specific surface area of the inorganic material is less ^than 4500 cm ² / g, the viscosity of the mortar cannot be sufficiently obtained, and it becomes difficult to obtain the dust suppressing effect at the time of spraying. There is a problem of diminishing. The brain specific surface area of the inorganic material is preferably 5000 to 18000 cm ² / g, preferably 5500 to 16000 cm ² / g, from the viewpoint of further increasing the viscosity of the mortar and easily ensuring the initial strength development. More preferred.

In the thickening admixture for spraying of the present embodiment, the mass ratio of the inorganic material to the thickener ([mass of the inorganic material] / [mass of the thickener]) is 0.2 to 3.5. If the mass ratio of the inorganic material is less than 0.2, the viscosity increases and the pumping property and the mixing property of the quick-setting agent decrease, which adversely affects the quick-setting performance. If the mass ratio of the inorganic material exceeds 3.5, the viscosity of the mortar cannot be sufficiently obtained, and it becomes difficult to obtain the dust suppressing effect at the time of spraying. The mass ratio of the inorganic material to the thickener is 0.22 to 2.5 from the viewpoint that the viscosity of the mortar is further increased, the effect of suppressing dust generated at the time of spraying can be easily obtained, and the initial strength development can be easily secured. It is preferably present, and more preferably 0.24 to 1.5.

The preparation of the thickening admixture for spraying is not particularly limited, and the above-mentioned thickening agent and the inorganic material may be mixed.

[Spray material]
The spraying material according to another embodiment of the present invention includes cement, the thickening admixture for spraying, and a quick-setting agent.

The cement is not particularly limited, and various Portland cements such as ordinary, early-strength, ultra-fast-strength, low-heat and moderate heat, various mixed cements in which fly ash or silica mixture is mixed with these Portland cements, incineration ash, etc. Eco-cement or the like made from waste such as sludge can be used. As the cement, one type may be used alone, or two or more types may be used in combination.

The thickening admixture for spraying is as described above. The content of the thickening admixture for spraying is 0. From the viewpoint that the viscosity of the mortar is further increased, the amount of dust generated during spraying is likely to be reduced, and the initial strength development is easily ensured. It is preferably 04 to 0.25 parts by mass, more preferably 0.06 to 0.15 parts by mass, and even more preferably 0.07 to 0.1 parts by mass.

The quick-setting agent is not particularly limited, and a powder quick-setting agent, a slurry-like quick-setting agent in which a liquid is mixed with the powder quick-setting agent, a liquid quick-setting agent, or the like can be used. The quick-setting agent can be appropriately selected according to the purpose. For example, a powder quick-setting agent is preferable from the viewpoint of further improving the initial strength development, and a powder quick-setting agent is preferable, and from the viewpoint of further reducing the generated dust and rebound. Is preferably a slurry-like quick-setting agent or a liquid quick-setting agent.

The powder quick-setting agent is preferably a powder quick-setting agent containing calcium aluminates as an active ingredient. Calcium aluminates include calcium aluminate, calcium _{haloaluminate} , calcium sodium aluminate, calcium sulfate, and those obtained by solid-dissolving or combining SiO ₂ , K2 O, Fe ₂ O ₃ , TIO ₂ , and the like. Can be mentioned. One type of calcium aluminate may be used alone, or two or more types may be used in combination. The calcium aluminates may be crystalline, amorphous, or a mixture of crystalline and amorphous. From the viewpoint of further improving the initial strength development, the degree of powderiness of the calcium aluminates is preferably 3000 cm ² / g or more, and more preferably 5000 cm ² / g or more in terms of the specific surface area of the brain. The degree of powderiness of the calcium aluminates is preferably 8000 cm ² / g or less in terms of the specific surface area of the brain. In addition to calcium aluminates, various carbonates, sulfates, nitrates, aluminates, hydroxides, oxides and the like can be added to the powder quick-setting admixture.

Examples of the liquid quick-setting agent include a liquid quick-setting agent containing aluminum sulfate, aluminate, sodium silicate, or the like as an active ingredient. The liquid quick-setting admixture containing aluminum sulfate as an active ingredient is usually prepared as an aqueous solution by mixing powdered aluminum sulfate (or a hydrate thereof) with water, but is not particularly limited thereto. The liquid quick-setting admixture containing aluminum sulfate as an active ingredient may have the same effect as that prepared by adjusting the soluble aluminum component and a sulfur source such as sulfuric acid to prepare aluminum sulfate as an aqueous solution. The concentration of aluminum sulfate is preferably 7% by mass or more, more preferably 15 to 65% by mass, still more preferably 30 to 60% by mass, based on the total amount of the liquid quick-setting admixture. The liquid quick-setting admixture may further contain other components to the extent that the effects of the present invention are not impaired. Examples of other components include precipitated silica, alkanolamine, fluoride, magnesium sulfate, oxalic acid and the like.

The content of the quick-setting admixture is preferably 4.5 to 13.0 parts by mass and 5.0 to 10.0 parts by mass with respect to 100 parts by mass of the cement from the viewpoint of further improving the initial strength development. It is more preferable that it is a part. When a liquid quick-setting admixture is used, the above-mentioned content is converted into the solid content of an active ingredient such as aluminum sulfate contained in the liquid quick-setting admixture.

The spraying material of the present embodiment may include a fine aggregate or a coarse aggregate. Examples of these aggregates include river sand, quartz sand, crushed sand, cold water stone, limestone sand and the like. These aggregates may be used alone or in combination of two or more.

The content of the fine aggregate in the mortar is preferably 100 to 450 parts by mass, more preferably 200 to 400 parts by mass, and further preferably 250 to 350 parts by mass with respect to 100 parts by mass of the cement. preferable.

The total content of fine aggregate and coarse aggregate in concrete is preferably 330 to 570 parts by mass, more preferably 330 to 550 parts by mass, and 350 to 530 parts by mass with respect to 100 parts by mass of cement. Is more preferable.

In addition to the above-mentioned constituent components, the spraying material of the present embodiment may contain other components as long as the effects of the present invention are not lost. Other components include, for example, water reducing agents, retarding agents, swelling agents, shrinkage reducing agents, pigments, defoaming agents, foaming agents, fibers and polymers. As for the other components, one type may be used alone, or two or more types may be used in combination.

In the spraying material of the present embodiment, the water content is preferably 30 to 75 parts by mass, more preferably 35 to 70 parts by mass, and 40 to 68 parts by mass with respect to 100 parts by mass of cement. It is more preferable to have.

The spraying material of the present embodiment can be produced by mixing each of the above materials. The mixing method is not particularly limited and can be appropriately set according to the purpose of use. However, it is preferable to mix these materials immediately before use because the mixture of cement, quick-setting admixture and water cures rapidly.

As a spraying method, for example, powders such as cement, a thickening admixture for spraying, and aggregates are mixed, and the mixed powder and a mixed solution of water and a quick-setting admixture are sent by separate hoses or the like. Dry method of mixing and spraying at the tip of the spray nozzle, cement, thickening admixture for spraying, aggregate, etc., and mortar / concrete mixed with water and quick-setting agent are pressure-fed with separate hoses, etc. A wet method of mixing and spraying at the tip can be mentioned. The spraying method is preferably a wet method.

Since the thickening admixture for spraying of the present embodiment can impart viscosity to the spraying material mixed with the thickening admixture, it is possible to reduce the generated dust and further increase the initial strength development. can. Therefore, the thickening admixture for spraying and the spraying material using the thickening admixture for spraying of the present embodiment can be suitably used because they can work more safely in a closed space such as a tunnel in addition to the normal spraying work. ..

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

[material]
The materials used in the examples are as follows.
・ Cement (ordinary Portland cement)
・ Fine aggregate (quartz sand)
・ Thickener (methyl cellulose-based thickener)
-Inorganic material A: anhydrous gypsum, brain specific surface area 12800 cm ² / g
B: Anhydrous gypsum, brain specific surface area 8400 cm ² / g
C: Anhydrous gypsum, brain specific surface area 6300 cm ² / g
D: Anhydrous gypsum, brain specific surface area 4100 cm ² / g
E: Fly ash, brain specific surface area 5600 cm ² / g
・ Rapid binder (powder rapid binder containing amorphous calcium aluminate and sodium aluminate)

[Preparation of spray material]
Water was added to cement, fine aggregate, thickener, and inorganic material in an environment of 20 ° C., and the mixture was kneaded with a mortar mixer manufactured by Hobart to prepare a base mortar. A quick-setting agent was added to the base mortar to prepare a spraying material. The compounding ratio of each material is shown in Table 1.

[Evaluation methods]
Each item was evaluated by the following method. The evaluation results are shown in Table 2.
-Consistency JIS R 5201: 2015 "Physical test method for cement" 12. According to the flow test, the flow value (0 strokes, 15 strokes) of the base mortar was measured in an environment of 20 ° C.
Viscosity test The base mortar was filled in a cylindrical container with an inner diameter of 75 mm and a height of 75 mm that could be opened and closed at the bottom under an environment of 20 ° C. Forty-five seconds after adding water, the bottom surface of the cylindrical container was opened, the base mortar was dropped from a position of 1 m in height, and the scattering size of the falling object was measured. For the scattering dimension, the maximum length of the spreading surface of the falling object and the length of the spreading surface perpendicular to this were measured, and the average value was calculated.
-Proctor intrusive resistance test After adding a quick-setting agent to the base mortar in an environment of 20 ° C, a Procter intrusive resistance test was conducted using a hydraulic Proctor tester. The test method was carried out in accordance with JSCE-D 102-2013. The time when the quick-setting admixture was added was set to 0 seconds, and the mixture was stirred with a mortar mixer for 5 seconds and filled in a mold to perform a test.

From the results in Table 2, in the case of the formulation of the example, the spread by the drop test is small and the viscosity of the base mortar is increased, so that the dust suppressing effect is improved, and the initial strength development (30 after the addition of the quick-setting admixture) is improved. It can be seen that the Procter penetration resistance value) at the time of seconds is also high.

Claims (2)

A thickening admixture for spraying, which comprises a methylcellulose-based thickener and an inorganic material such as gypsum and / or fly ash .
The brain specific surface area of the inorganic material is 4500 to 20000 cm ² / g.
A thickening admixture for spraying, wherein the mass ratio of the inorganic material to the thickener ([mass of the inorganic material] / [mass of the thickener]) is 0.2 to 3.5. The cement, the thickening admixture for spraying according to claim 1, and the quick-setting agent are included.
A spraying material in which the content of the thickening admixture for spraying is 0.04 to 0.25 parts by mass with respect to 100 parts by mass of the cement .
However, the thickener other than the thickening admixture for spraying and the inorganic material having a brain specific surface area of 4500 to 20000 cm ² / g are not included.