JP6400639B2 - Spraying material and spraying method using the same - Google Patents

Description

The present invention relates to a rebound reducing agent, a spraying material, and a spraying method using the rebound reducing agent used when spraying rapidly setting cement concrete to an exposed natural ground surface in tunnels such as roads, railways, and conduits. About.

Conventionally, in order to prevent collapse of exposed ground such as tunnel excavation, a rapid setting concrete spraying method in which a liquid quick setting agent is mixed with concrete is used. (Patent Documents 1, 2, and 3)
This method is usually conducted at a mixing plant installed at the excavation site. Cement, aggregate, and water are metered and mixed to prepare concrete for spraying, transported by an agitator car, and pumped by a concrete pump. And it is a construction method which mixes with the quick setting agent pumped from the other by the confluence pipe | tube provided in the middle, sets it as quick setting spray concrete, and sprays it to a natural ground surface until it becomes predetermined thickness.
However, this method has a problem that curing is slow and it takes time to move to the next step, which is economically undesirable.
In view of this, a spraying material using polyethylene oxide and a trisphenol-based condensate or a bisphenol-based condensate, aluminum sulfate or an alkali metal silicate has been proposed as a method of spraying the slope. (Patent Documents 4, 5, and 6)
However, the time required for curing is slow, and the amount of dust generated is high, which causes problems in worker safety.

Japanese Patent No. 3600155 Japanese Patent No. 3960590 Japanese Patent No. 4037160 JP 2001-335352 A JP 2001-335353 A JP 2001-335350 A

  The present invention provides a cement admixture for a spraying material, a spraying material, and a spraying method using the same, which have a fast curing time, high adhesion to a tunnel ground, and reduced generation of dust.

  That is, the present invention provides (1) a cement admixture for spraying material comprising a polymer having aluminum sulfate, protein, and carboxylic acid or a monovalent salt thereof as main constituent monomer units, and (2) carvone. (1) Cement admixture for spray material, (3) Cement and (1) or (2) Cement admixture for spray material, wherein the acid or its monovalent salt is acrylic acid, methacrylic acid or maleic acid (4) Spraying material comprising (3) spraying material comprising 0.1 to 5 parts of aluminum sulfate in terms of solid content with respect to 100 parts of cement (4) ) Or (4) spraying method using the spraying material.

  By the cement admixture for spray material of the present invention, the spray material and the spray method using the same, the curing time is fast, the adhesion to the tunnel ground is high, the generation of dust is suppressed and the safety to the worker is increased. High effect such as shortening the construction period.

Hereinafter, the present invention will be described in detail.
In the present invention, parts are based on mass unless otherwise specified.
The cement concrete referred to in the present invention is a general term for mortar and concrete.

Aluminum sulfate used in the present invention reduces slump by mixing with cement concrete and prevents dripping or sliding of cement concrete immediately after spraying. Polyalkylene oxide and carboxylic acid or monovalent thereof By using in combination with a polymer having a salt as a main constituent monomer unit, the effect of preventing dripping or slipping of cement concrete immediately after spraying is increased compared to the case where these are used alone.
Aluminum sulfate has an anhydrous form and a hydrated form in powder form, and is also available as an aqueous solution by dissolving in water. Either of these can be used, but of these, it has good mixing properties with cement concrete. To an aqueous solution.
The amount of aluminum sulfate used is preferably 0.1 to 5 parts, more preferably 0.5 to 3 parts in terms of solid content (anhydride) with respect to 100 parts of cement. If it is less than 0.1 part, adhesion of cement concrete may be small, and if it exceeds 5 parts, setting and hardening of cement concrete may be promoted too much and the rebound rate may be increased.

The protein used in the present invention gives viscosity to cement concrete by interaction with a polymer having carboxylic acid or its monovalent salt as a main constituent monomer unit, and causes dripping and shearing of cement concrete immediately after spraying. It is to prevent.
The protein is a polymer having a polypeptide chain, and is not particularly limited as long as the number of constituent amino acids is 50 or more, that is, a molecular weight of 5000 or more. Prolamin, collagen, gelatin, glue, casein, Those made of petroleum artificial proteins and the like and mixtures thereof can be used.
The amount of protein used is preferably 0.01 to 5 parts, more preferably 0.5 to 3 parts, per 100 parts of cement. If it is less than 0.01 part, the viscosity of cement concrete is small, and dripping may occur when sprayed, and cement concrete may flow down from the slope. If it exceeds 5 parts, the viscosity of cement concrete will increase, which will hinder pumpability. May occur.

A polymer having a carboxylic acid or a monovalent salt thereof as a main constituent monomer unit (hereinafter referred to as a polymer) used in the present invention imparts plasticity to cement concrete at the moment when it reacts with protein, It prevents dripping of cement concrete from the affixed surface and reduces the rebound rate. Carboxylic acid or a monovalent salt thereof (hereinafter referred to as “unsaturated carboxylic acid (salt)”) is a main constituent monomer unit. Specific examples of the unsaturated carboxylic acid (salt) include acrylic acid. Methacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic acid and cinnamic acid and monovalent salts thereof. Two or more of these unsaturated carboxylic acids (salts) may be used in combination. In the present invention, acrylic acid (salt), methacrylic acid (salt) or maleic acid (salt) is preferably used, and acrylic acid (salt) is particularly preferably used.
A low molecular weight polymer having a weight average molecular weight of 3000 or more and 25000 or less is preferred. If it is lower than 3000, the plasticity may not be sufficient, and if it exceeds 25000, the pumpability may decrease.
The amount of the polymer used is preferably 0.1 to 10 parts, more preferably 0.5 to 5 parts, relative to 100 parts of cement. If the amount is less than 0.1 part, the viscosity of the cement concrete is small, and dripping may occur when sprayed, and the cement concrete may flow down from the slope. If the amount exceeds 0.5 part, the viscosity of the cement concrete will increase and the pumpability will be increased. May cause trouble.

The cement used in the present invention is not particularly limited, and various portland cements such as normal, early strength, very early strength, moderate heat, and low heat, and blast furnace slag, fly ash, limestone fine powder, etc. In addition, various mixed cements mixed with silica, alumina cement, expanded cement, colloidal cement, and eco-cement can be used.

In the present invention, in addition to the above materials and aggregates such as sand and gravel, a water reducing agent, AE agent, fiber, setting accelerator, fine powder, etc. are used in a range that does not substantially impair the object of the present invention. Is possible.

In the present invention, naphthalene sulfonic acid formalin condensate, melamine sulfonic acid formalin condensate, polycarboxylic acid polymer compound and the like can be used as the water reducing agent. The AE agent prevents frost damage of cement concrete. The fiber is particularly effective for preventing cracks in the anchor portion.
In the present invention, examples of the setting accelerator include fluorine, alkali metal, alkanolamine, glycerin, silicate, alkali aluminate, slaked lime, gypsum, calcium aluminate, calcium sulfoaluminate, and the like. Is also possible.
Further, the fine powder fills the voids to form a dense structure and increases the strength, and silica fume or the like can be used.

  In the present invention, as an apparatus for mixing cement, aggregate, water and the like, an existing stirring apparatus 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. .

In the present invention, the amount of cement used in the cement concrete is preferably 330 to 500 kg / m ³ , and the water cement ratio is preferably 40 to 65%.

  As the spraying method of the present invention, a dry spraying method or a wet spraying method is possible. The dry spraying method is, for example, a method in which cement and aggregate are mixed and pneumatically fed, and water and a liquid quick-set agent are mixed and sprayed. The wet spraying method is, for example, a method in which cement, aggregate, and water are mixed in advance to form cement concrete, which is pumped or air-conveyed, and a liquid rapid setting agent is merged and mixed and sprayed. Among these, since the amount of dust may increase in the dry spray method, it is preferable to use the wet spray method.

  In the spraying method of the present invention, conventional spraying equipment or the like can be used. The spraying equipment is not particularly limited as long as the spraying is sufficiently performed. For example, a concrete pump made by Shintec can be used for pumping cement concrete, and Okasan Kiko is used for pumping liquid quick setting agent. A squeeze pump made by the company can be used.

In the present invention, the pumping speed of cement concrete is preferably 4 to 20 m ³ / h, and the pumping pressure of cement concrete is preferably 2 to 6 MPa.

The amount of compressed air to which the cement admixture for spray material of the present invention is pumped and added to cement concrete is 4 to 4 in terms of preventing the cement concrete from entering the pumping tube of the admixture and blocking the pumping tube. 10 m ³ / min is preferable.

The joining point of the cement admixture for spray material of the present invention and cement concrete can have a structure in which the shape of the tube and the inner wall are likely to be spiral or turbulent in order to improve the mixing property. .

Hereinafter, description will be made based on experimental examples of the present invention.

"Experiment 1"
A shotcrete with a unit cement amount of 455 kg / m ³ , W / C = 45%, and s / a = 70% was prepared, and this was fed by a concrete pump “Alivar 280” at a pumping speed of 4 m ³ / hr, 0 It was pneumatically fed at a pressure of 4 MPa.
The protein shown in Table 1 was mixed with concrete in advance with respect to 100 parts of cement in the concrete. The amount of water reducing agent used in the concrete was adjusted so that the slump would be about 20 cm.
In addition, the polymer A and aluminum sulfate are pumped at the same time by pumps, and to 100 parts of cement in concrete, 1.5 parts and 1 part (in terms of solid content) are attached to the branch pipes attached in front of the nozzle. It was press-fitted with compressed air, mixed with concrete and sprayed. The results are also shown in Table 1.

<Materials used>
Cement: Ordinary Portland cement, commercially available fine aggregate: Standard sand, Cement Association, Specific gravity 2.64
Water reducing agent: polycarboxylic acid-based high-performance water reducing agent, commercial product water: tap water aluminum sulfate: powdered aluminum sulfate 14 hydrate, commercial product protein A: casein, commercial product protein B: gelatin, commercial product polymer A: polyacrylic Acid, average molecular weight 15,000, commercial product

<Measurement method>
Sagging: While maintaining the spray nozzle at a constant height, the presence or absence of spray sagging was confirmed uniformly to a thickness of 3 cm, and the length of sagging was measured and used as an adhesion index.
Curing time: The time from when the spray material was sprayed until the dent disappeared by finger touch was used as an index of adhesion.
Dust amount: Measured at a fixed position of 5 m from the spraying place after 5 minutes of spraying. As a measuring device, a digital dust meter P-5L manufactured by Shibata Kagakusha was used.

From Table 1, it was found that, by mixing a predetermined amount of protein in the present invention, the adhesion is better and the amount of dust can be suppressed.

"Experimental example 2"
The test was conducted in the same manner as in Experimental Example 1 except that 100 parts of cement in concrete was mixed with 1 part of protein and the polymer shown in Table 2 was used. The results are also shown in Table 2.
As a comparison, as shown in Table 2, a trisphenol-based condensate or a bisphenol-based condensate was added as an alternative to the polymer.

<Materials used>
Polymer A: polyacrylic acid, average molecular weight 15,000, commercially available polymer B: sodium polyacrylate, average molecular weight 15,000, commercially available polymer C: maleic acid, average molecular weight 15,000, commercially available Product polymer D: methacrylic acid, average molecular weight 15,000, commercial product trisphenol-based condensate: 4-aminobenzenesulfonic acid, average molecular weight 20,000, commercial product bisphenol-based condensate: bisphenol S, average molecular weight 20,000, Commercial item

From Table 2, it was found that, in the present invention, a predetermined amount of the polymer is mixed to provide better adhesion and suppress the amount of dust.

"Experiment 3"
Performed in the same manner as in Experimental Example 1 except that 1 part of protein was mixed with 100 parts of cement in concrete, 1.5 parts of polymer A and aluminum sulfate (in terms of solid content) shown in Table 3 were used. It was. The results are also shown in Table 3.
As a comparison, an alkali metal silicate added as an alternative to aluminum sulfate was also carried out as shown in Table 3.

<Materials used>
Alkali metal silicate: No. 3 water glass, commercial product

From Table 3, it was found that, in the present invention, a predetermined amount of aluminum sulfate was mixed, thereby providing better adhesion and suppressing the amount of dust.

  With the cement admixture for spray material of the present invention, the spray material and the spraying method using the same, when constructing the shotcrete of the tunnel, the curing time is fast, the adhesion to the tunnel ground is high, and the dust There are effects such as suppressing occurrence and high safety for workers and further shortening the construction period.

Claims (3)

For 100 parts by mass of cement, 0.5 to 5 parts by mass of aluminum sulfate in terms of solid content, 0.01 to 5 parts by mass of protein, and carboxylic acid or a monovalent salt thereof as main constituent monomer units A spraying material containing 0.1 to 10 parts by mass of the polymer. The spraying material according to claim 1, wherein the carboxylic acid or a monovalent salt thereof is acrylic acid, methacrylic acid or maleic acid. A spraying method using the spraying material according to claim 1.