JP5249012B2 - Powder dust reducing agent - Google Patents

Description

  The present invention relates to a powdery dust reducing agent, and more particularly to a powdery dust reducing agent that can be efficiently supplied to a concrete material by a quantitative supply device when manufacturing base concrete of shotcrete.

  Spray materials such as shotcrete and spray mortar are often used for tunnels, especially mountain tunnels using the NATM method. However, due to the compressed air used when spraying the spray material, dust derived from concrete (in the present invention, including mortar) is generated during spraying. This dust is highly alkaline and may adversely affect the human body. Admixtures that suppress the generation of this dust, that is, dust reducing agents have been proposed (see, for example, Patent Documents 1 to 5). In recent years, dust reducing agents have been used more frequently in the field of spray construction because they are highly effective in improving the working environment during spray construction.

The dust reducing agent contains, as an active ingredient, a substance that increases the viscosity of concrete such as water-soluble cellulose. However, for the purpose of improving the dust reduction effect, the purpose of improving workability, or the purpose of increasing the strength of the concrete after hardening, etc., water reducing agents such as polycarboxylic acid polymers and lignin sulfonates are used as dust reducing agents. 1 type or 2 types or more chosen from the active ingredient of an agent and an antifoamer may be contained further. When a dust reducing agent is mixed with shotcrete, the dust reducing agent is usually aggregate, cement, other admixtures or water that becomes the base concrete material when the base concrete is manufactured before the quick setting agent is added. Alternatively, it is added to the kneaded base concrete. At this time, for example, a quantitative supply device represented by the schematic diagrams of FIGS. 1 to 3 is used. However, when a powdery dust reducing agent containing water-soluble cellulose and a powdery defoaming agent is added to the base concrete or its material with a quantitative supply device, the amount of the powdery dust reducing agent attached to the hopper of the quantitative supply device There are many cases, and sometimes it is blocked in the metering apparatus.
JP 2008-56537 A JP 2005-154239 A JP 2005-154240 A JP 2002-189529 A Japanese Patent Laid-Open No. 5-105493

  An object of the present invention is to solve the above-described problem, that is, to provide a powdery dust reducing agent that hardly adheres to a hopper of a quantitative supply device. More specifically, an object of the present invention is to provide a powdery dust reducing agent containing water-soluble cellulose and a powdered antifoaming agent that hardly adheres to a hopper of a quantitative supply device.

As a result of intensive studies for solving the above problems, the present inventors have found that the above problems can be overcome by containing a water-soluble cellulose ether and a specific powdery antifoaming agent, and have completed the present invention. It was. That is, this invention is a powdery dust reducing agent represented by the following (1 ) .
(1) 10 to 60 parts by mass of a liquid antifoaming agent, and 5 to 50 parts by mass of an organic liquid in which polyoxyalkylene ether and mineral oil are used in combination on 20 to 50 parts by mass of an inorganic powder; Contains water-soluble cellulose ether, 5 to 30 parts by weight of powdered antifoaming agent and 95 to 70 parts by weight of water-soluble cellulose ether with respect to 100 parts by weight of the total amount of powdered antifoaming agent and water-soluble cellulose ether. A powdery dust reducing agent .

  ADVANTAGE OF THE INVENTION According to this invention, the powdery dust reducing agent which is hard to adhere to the hopper of a fixed amount supply apparatus is obtained. More specifically, a powdery dust reducing agent containing water-soluble cellulose and a powdered antifoaming agent that is difficult to adhere to the hopper of the quantitative supply device is obtained. Since the powdery dust reducing agent of the present invention hardly adheres to the hopper of the quantitative supply device, it can be stably supplied to the base concrete using the quantitative supply device. This stabilizes the quality of the base concrete and the shotcrete mixed with the powdery dust reducing agent of the present invention.

  Examples of the water-soluble cellulose ether used in the present invention include hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), hydroxymethyl cellulose (HMC), hydroxyethyl methyl cellulose (HEMC), hydroxypropyl methyl cellulose (HPMC), and hydroxyethyl ethyl cellulose (HEEC). Etc. Hydroxyethyl methylcellulose and hydroxypropylmethylcellulose are preferred. The water-soluble cellulose ether may be used alone or in combination of two or more. Moreover, you may use what added glyoxal to these water-soluble cellulose ethers. The water-soluble cellulose ether used in the present invention preferably has a viscosity of a 2% by weight aqueous solution of 30,000 to 100,000 mPa · s at 20 ° C. When the viscosity is less than 30000 mPa · s, it is necessary to add a large amount of a dust reducing agent in order to suppress dust. In addition, if the viscosity exceeds 100,000 mPa · s, there may be a lot of dust because the dissolution rate in water becomes small. In view of the effect of suppressing dust and the compressive strength of the sprayed concrete, it is more preferably 40000 to 80000 mPa · s. The viscosity of the aqueous solution of water-soluble cellulose ether is measured using a digital viscometer DV-I + manufactured by Brookfield. When combining, it is preferable that the viscosity when the combined product is a 2% by weight aqueous solution is 30,000 to 100,000 mPa · s at 20 ° C.

  The content of the water-soluble cellulose ether in the powdery dust reducing agent of the present invention is 70 to 95 parts by mass with respect to 100 parts by mass in total of the water-soluble cellulose ether and the powdered antifoaming agent. If it is less than 70 mass parts, it will be difficult to suppress the dust of shotcrete. If it exceeds 95 parts by mass, the strength of the shotcrete will decrease. It is possible to suppress the dust of shotcrete and make it 80-90 parts by mass with respect to 100 parts by mass in total of the water-soluble cellulose ether and the powder antifoaming agent, since it is difficult for air bubbles to enter the base concrete and adhere to the hopper. preferable

The powdery antifoaming agent used in the present invention was supported by 10 to 60 parts by mass of a liquid antifoaming agent and 5 to 50 parts by mass of an organic liquid using polyoxyalkylene ether and mineral oil in combination with 20 to 50 parts by mass of an inorganic powder. Is. Examples of the liquid antifoaming agent used here include tributyl phosphate or polydimethylsiloxane in addition to a commercially available defoaming agent for cement, a commercially available antifoaming agent for cement mortar, or a commercially available antifoaming agent for concrete. Antifoaming agents may be used alone or in combination of two or more.

The content of the liquid antifoaming agent in the powdered antifoaming agent is 10 to 60 parts by mass with respect to 100 parts by mass in total of the liquid antifoaming agent, the organic liquid using the polyoxyalkylene ether and mineral oil, and the inorganic powder. . If it is less than 10 parts by mass, it is difficult to obtain the effect of the antifoaming agent, and if it exceeds 60 parts by mass, it tends to adhere to the hopper. Since the effect of adding the antifoaming agent is obtained and it is difficult to adhere to the hopper, the preferred content of the liquid antifoaming agent in the powdered antifoaming agent is a combination of the liquid antifoaming agent, polyoxyalkylene ether and mineral oil. It shall be 20-55 mass parts with respect to a total of 100 mass parts of organic liquid and inorganic powder.

Used in the present invention, polyoxyalkylene ethers and mineral oil combination with organic liquid as (hereinafter referred to simply as "organic liquid".) Is, with one kind or two or more kinds of polyoxyalkylene ethers and mineral oil , Polyoxyalkylene ether and mineral oil are used in combination.

  Content of the organic liquid in a powdery antifoamer shall be 5-50 mass parts with respect to a total of 100 mass parts of a liquid antifoamer, an organic liquid, and an inorganic powder. If it is less than 5 parts by mass, it tends to adhere to the hopper, and if it exceeds 50 parts by mass, air bubbles easily enter the base concrete. Since it is difficult for bubbles to enter the base concrete and adhere to the hopper, the preferable content of the organic liquid in the powdered antifoaming agent is 10 parts per 100 parts by mass in total of the liquid antifoaming agent, the organic liquid and the inorganic powder. ˜45 parts by mass. By making the content of the organic liquid in the powdered antifoaming agent within this range (10 to 45 parts by mass), the angle of repose of the powdery dust reducing agent becomes less than 50 °, and it becomes more difficult to adhere to the hopper. To preferred.

  The inorganic powder used in the present invention is not limited as long as it is in the form of a powder even if the liquid defoamer and the organic liquid are carried in the same mass as the liquid defoamer and the organic liquid. Silica, sepiolite, talc, mica, diatomaceous earth, zeolite, pearlite and the like, and one or more of these can be used.

  The content of the inorganic powder in the powdered antifoaming agent is 20 to 50 parts by mass with respect to a total of 100 parts by mass of the liquid antifoaming agent, the organic liquid, and the inorganic powder. If the amount is less than 20 parts by mass, the antifoaming agent may not be powdered. If the amount exceeds 50 parts by mass, bubbles tend to enter the base concrete or adhere to the popper. Since the defoamer is in powder form, it is difficult for air bubbles to enter the base concrete and adhere to the hopper. Therefore, the preferred content of the inorganic powder in the powder defoamer is that of the liquid defoamer, organic liquid and inorganic powder. It is set as 30-40 mass parts with respect to a total of 100 mass parts.

  Content of the powder antifoamer in the powdery dust reducing agent of this invention shall be 5-30 mass parts with respect to a total of 100 mass parts of water-soluble cellulose ether and a powder antifoamer. If it is less than 5 parts by mass, air bubbles can easily enter the base concrete or adhere to the popper. When it exceeds 30 parts by mass, it is difficult to suppress dust from shotcrete. The powder defoaming agent content is 10 to 100 parts by mass of water-soluble cellulose ether and powder defoaming agent because the dust in the shotcrete is suppressed, and it is difficult for bubbles to enter the base concrete and adhere to the hopper. It is preferable to set it as -20 mass parts.

  The powdery dust reducing agent of the present invention may contain optional components other than the water-soluble cellulose ether and the powdered antifoaming agent as necessary within a range not impairing the effects of the present invention. Examples of optional components include water reducing agents (including high-performance water reducing agents, high-performance AE water reducing agents, and fluidizing agents) such as polycarboxylic acid polymers and lignin sulfonates, setting modifiers, bulking agents, and swelling. Examples thereof include materials, rust preventives, shrinkage reducing agents, pigments, fibers, water repellents, and whitening prevention agents. These optional components may be used alone or in combination of two or more.

  The method for producing the powdery dust reducing agent of the present invention is not particularly limited. For example, a predetermined amount is used using a mixer such as a gravitational concrete mixer, a Henschel mixer, a Nauter mixer, a Roedige mixer, a V-type mixer, or a ribbon mixer. It can manufacture by mixing each material of the powdery dust reducing agent of this invention. The mixer used at this time may be a continuous mixer or a batch mixer. The order in which each material is charged into the mixer is not particularly limited. They may be added one by one, or some or all of them may be added simultaneously. Moreover, the powdery dust reducing agent of this invention can also be manufactured with the method of measuring and throwing each material into containers, such as a bag and a polyethylene container.

  The powdery dust reducing agent of the present invention can be used in the same manner as a normal powdery dust reducing agent, and can be used as an aggregate, cement, or other material to be used as the base concrete material when the base concrete is manufactured before the quick setting agent is added. Add to admixture or water or kneaded base concrete. At this time, for example, the quantitative supply device shown in the schematic diagrams of FIGS. 1 to 3 is used. Base concrete is kneaded and manufactured by a conventional method. An apparatus and a kneading apparatus used for kneading are not particularly limited, but it is preferable to use a mixer because a large amount can be kneaded. The mixer that can be used may be a continuous mixer or a batch mixer, such as a pan concrete mixer, a pug mill concrete mixer, a gravity concrete mixer, a grout mixer, a hand mixer, and a plaster mixer. The base concrete contained in the produced powdery dust reducing agent of the present invention is sprayed on the lining surface of a tunnel or the wall surface of a concrete septic tank using a conventional concrete spraying device and using a conventional quick setting agent. It is done.

[Example 1]
A powdery dust reducing agent (abbreviation: AD-A) was produced by mixing 90 parts by weight of water-soluble cellulose ether and 10 parts by weight of powdered antifoaming agent A using a Ladige mixer for 3 minutes. The materials used at this time are shown below. The quality test of the produced powdery dust reducing agent was performed as shown below. The results are shown in Table 1. Also, base concrete (water cement ratio: 60%, fine aggregate ratio: 60%) in which 0.1 parts by mass of the prepared powdery dust reducing agent is mixed with 100 parts by mass of cement is kneaded for 90 seconds with a pan-type concrete mixer. Manufactured. Measure the slump and the change over time of the air amount, perform a spray test using the prepared base concrete, measure the amount of dust generated, and the amount of dust generated when using the base concrete without the addition of the dust reducing agent as 100 The relative ratio of the amount of dust generated was determined. The materials and test methods used are shown below, and the results of the concrete test are shown in Table 2.

<Materials used>
Powdered antifoaming agent A: Powdered form in which 35 parts by mass of amorphous silica was supported with 5 parts by mass of polyoxyalkylene ether, 45 parts by mass of a commercially available antifoaming agent comprising a nonionic surfactant and 15 parts by mass of mineral oil. Antifoaming agent Water-soluble cellulose ether: Hydroxypropyl methylcellulose to which glyoxal was added (Brookfield Digital Viscometer DV-I + (spindle; RV-7 (RV / HA / HB-7), rotation speed: 10 rpm) Viscosity of 2% by weight aqueous solution at 20 ° C. using 49.
Cement: Ordinary Portland cement (manufactured by Taiheiyo Cement)
Fine aggregate: Land sand from Shizuoka Prefecture (surface dry density; 2.57 kg / cm ³ , coarse particle ratio; 2.60)
Coarse aggregate: Crushed stone from Ibaraki Prefecture (surface dry density: 2.62 kg / cm ³ , coarse particle ratio: 6.02)
Water: tap water

<Quality test method>
-Powder flowability test A 100 g sample of the powdery dust reducing agent was placed in a plastic bag, shaken by hand 10 times, and then tilted to 45 °. The state that the sample collapsed at this time was visually confirmed and evaluated. At this time, the thing which collapsed by the lump was evaluated as "bad", and the thing which collapsed like flowing was evaluated as "good".
-Angle of repose measurement The angle of repose of the produced powdery dust reducing agent was measured twice with "Powder Tester" (trade name) manufactured by Hosokawa Micron, and the average value was taken as the angle of repose of the powdery dust reducing agent.
・ Discharge rate measurement test Powder that was discharged until 8 kg of the prepared powder reducing agent was discharged into the hopper of the quantitative supply device represented by the schematic diagram in FIGS. 1 to 3 and no sample was discharged from the discharge port. The total discharge amount of the dust reducing agent was measured in g, and the discharge rate was determined by the following formula (1).
Emission rate (%) = ((total emission) / 8000) x 100 (1)

<Concrete test>
-Slump test According to JIS A 1101-1998 "Concrete slump test method", the slump from the end of mixing of the base concrete to 90 minutes later was measured.
-Air quantity test According to JIS A 1128-1999 "Test method by pressure of air quantity of fresh concrete (air chamber pressure method)", the air quantity from the end of mixing of base concrete to 90 minutes after was measured.
-Spraying test The base concrete was pumped by using a concrete pumping machine “Ariba 260” manufactured by Fuji Bussan Co., Ltd. From one of the merging and mixing sections provided on the way, cement mineral powder quick setting agent ("Shot Master" manufactured by Taiheiyo Materials Co., Ltd.) is pumped by the quick setting agent addition device "Q Gun" manufactured by Japan Private Co. 7 parts by weight with respect to the part was mixed in the merging and mixing part to produce a quick setting shot concrete. This quick setting spray concrete was sprayed for 3 minutes at a spraying amount of 3 m ³ / h to a simulated tunnel having a height of 3 m and a width of 5 m.
・ Dust amount measurement The simulated tunnel is sealed with a sheet, and the dust amount (count number) is measured with a light scattering digital dust meter (Model 3411 manufactured by Nippon Kanomax Co., Ltd.) at a position 3 m from the spraying place every minute. The relative value when the count number in the case of adding no powdery dust reducing agent was 100 was shown as the relative ratio of the amount of dust.

[Comparative Example 1]
As a powdery antifoaming agent, the powdery antifoaming agent B shown below is used, and 90 parts by mass of the above-mentioned water-soluble cellulose ether and 10 parts by mass of the powdery antifoaming agent B are mixed for 3 minutes by a Laedige mixer. Thus, the same test as in Example 1 was conducted except that a powdery dust reducing agent (abbreviation: AD-B) was prepared and used in the test. The results are shown in Tables 1 to 3 together with the results of Example 1.
<Materials used>
Powder defoamer B: Powder defoamer in which 65 parts by mass of a commercially available defoamer comprising a nonionic surfactant is supported on 35 parts by mass of amorphous silica

  Since the powdery dust reducing agent (AD-A) of Example 1 corresponding to the example of the present invention had an angle of repose of less than 50 °, the discharge rate was as high as 91%. Moreover, this powdery dust reducing agent (AD-A) was sufficiently reducing the dust of shotcrete.

  The sprayed concrete using the powdery dust reducing agent of the present invention generates little dust and is sprayed on the lining surface of a tunnel, the wall surface of a concrete septic tank, or the like.

It is a schematic front view of a fixed amount supply apparatus. It is a schematic plan view of a fixed amount supply apparatus. It is a schematic side view of a fixed amount supply apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Constant supply apparatus 2 Hopper 3 Control operation box 4 Discharge port 5 Motor 6 Screw feeder

Claims (1)

10 to 60 parts by mass of a liquid antifoaming agent, and 5 to 50 parts by mass of an organic liquid in which polyoxyalkylene ether and mineral oil are used in combination on 20 to 50 parts by mass of an inorganic powder, and water-soluble cellulose Powdered dust containing ether, 5 to 30 parts by weight of powdered antifoaming agent and 95 to 70 parts by weight of water-soluble cellulose ether to 100 parts by weight of the total amount of powdered antifoaming agent and water-soluble cellulose ether Reducing agent.

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