JP6131063B2 - Liquid quick setting agent, cement composition using the same, and spraying method - Google Patents

Description

  The present invention relates to a liquid quick-setting agent, a cement composition using the same, and a spraying method used for cement concrete sprayed to an exposed natural ground surface in tunnels such as roads, railways, and conduits.

Conventionally, in order to prevent collapse of exposed ground such as tunnel excavation, a rapid setting concrete spraying method in which a quick setting agent is mixed with concrete is used (Patent Document 1).
This method is usually a metering and mixing plant installed at the excavation site, and cement, aggregate, and water are metered and mixed to prepare concrete for spraying, transported with an agitator car, and pumped with a concrete pump. This is a method of mixing with a quick-setting agent pumped from the other in a confluence pipe provided in the middle to make a quick setting sprayed concrete and spraying it to the ground surface until it reaches a predetermined thickness.

  As the quick setting agent, a powder quick setting agent in which alkali metal aluminate or alkali metal carbonate is mixed with calcium aluminate is often used. From the point that there is no chemical damage, it is desired to use an acidic liquid quick-setting agent mainly composed of an aluminum salt (Patent Documents 2 to 6).

In many cases, the aluminum salt used in the liquid quick-setting agent is a sulfate, and the higher the concentration, the higher the quick setting property, and the addition rate during spraying can be reduced.
However, when the high-concentration liquid accelerator is stored for a long period of time, precipitates may be generated in the liquid, the liquid may gel, or suspended particles may settle. The solubility of aluminum sulfate in water is 27% at 20 ° C. and varies depending on the coexisting solute and liquid temperature. However, the liquid accelerator containing aluminum sulfate having a solubility higher than the solubility is poor in storage stability and is immediately after production. It is difficult to maintain the properties. Use of a liquid quick-setting agent in which precipitates are formed in the liquid, the liquid is gelled, or suspended particles are settled, the pump is clogged, the mixing with concrete is poor, and it is excellent In some cases, the properties could not be obtained. In addition, since the solubility varies depending on the liquid temperature, this storage problem depends on the temperature to be stored, and may be more prominent when stored at high or low temperatures.

Japanese Patent Publication No. 60-4149 JP-A-10-87358 JP 2003-246659 A JP 2005-89276 A JP 2006-193388 A JP 2008-30999 A

As a result of various examinations of the previous problems, the present inventor, by adding a water-soluble cellulose ether to the liquid accelerating agent, uniformly disperses aluminum sulfate having a solubility higher than that in water without precipitating in water, The present invention has been completed by obtaining knowledge for solving the problems in the previous period.

  That is, the present invention includes (1) containing aluminum sulfate, water-soluble cellulose ether, and water, insoluble particles are dispersed in the liquid at −10 to 40 ° C., and 90% or more of the liquid is suspended in a volume ratio. (2) The liquid quick-setting agent of (1) having an aluminum sulfate concentration of 30 to 50% by weight and a water-soluble cellulose ether concentration of 0.01 to 5% by weight, and (3) a water-soluble cellulose ether (1) or (2) a liquid accelerator having an average molecular weight of 10,000 to 100,000, and (4) a liquid of any one of (1) to (3) further containing a fluorine compound Quick setting agent, (5) Liquid quick setting agent in any one of (1) to (4) further containing alcohol amines, (6) Viscosity at 20 ° C. is 300 to 5,000 mPa · s Any of (1)-(5) (7) A cement composition containing 3 to 20 parts by mass of the liquid accelerator of any one of (1) to (6) with respect to 100 parts by mass of cement, (8) (7 ) Spraying method using a cement composition

  The liquid quick-setting agent of the present invention is excellent in storage stability and fluidity, despite the high aluminum sulfate concentration, as compared with conventional liquid quick-setting agents. Furthermore, by using this liquid quick setting agent, there is an effect of improving the quick setting property and strength development property of the quick setting shot concrete as compared with the conventional liquid quick setting agent.

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

As the aluminum sulfate used in the present invention, any of anhydrides, hydrates, and aqueous solutions can be used, and one or more of these can be used. Among these, hydrates are preferable and 14 hydrates are more preferable in that the degree of separation during dissolution is low and the dispersibility is excellent.
30-50% is preferable and, as for the aluminum sulfate density | concentration of a liquid quick setting agent, 32-40% is more preferable. If it is less than 30%, excellent quick setting may not be obtained when mixed with concrete, and if it is 50% or more, the suspension has a high viscosity, poor fluidity, and difficult to pump. In some cases, a uniform liquid cannot be produced.

The water-soluble cellulose ether used in the present invention refers to a substance in which the hydroxyl group of cellulose is ether-substituted and has water solubility.
Specific examples include methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, and the like, and one or more of these can be used. Of these, carboxymethylcellulose is particularly preferred. In other water-soluble cellulose ethers, insoluble particles may be difficult to disperse uniformly, or the viscosity of the suspension may be high and pumping may be difficult. In addition, carboxymethylcellulose may be used in which some or all of the hydrogen atoms of the carboxyl group are substituted with alkali metals.

The concentration of the water-soluble cellulose ether in the liquid accelerator is preferably 0.01 to 5%, more preferably 0.1 to 3%. If it is less than 0.01%, insoluble particles may settle and may be easily separated, and if it is 5% or more, the suspension has a high viscosity and may be difficult to pump.

The average molecular weight of the water-soluble cellulose ether used in the present invention is preferably 10,000 to 100,000, more preferably 15,000 to 5,000. If it is less than 10,000, insoluble particles may settle and may be easily separated, and if it is 100,000 or more, the suspension has a high viscosity and may be difficult to pump.

The liquid quick setting agent of the present invention may contain a fluorine compound. The fluorine compound is used for the purpose of improving the setting property and initial strength development. The fluorine compound is not particularly limited as long as it is soluble in water or an acidic aqueous solution. Moreover, as long as it adds to a liquid and it becomes a uniform state, the order put in at the time of manufacture will not be ask | required.
Fluorine compounds include hydrogen fluoride, lithium fluoride, sodium fluoride, magnesium fluoride, potassium fluoride, aluminum fluoride, zinc fluoride, ammonium fluoride, potassium hydrogen fluoride, boron trifluoride, hexafluoride Examples include aluminum sodium, potassium aluminum hexafluoride, hydrogen silicofluoride, sodium silicofluoride, magnesium silicofluoride, potassium silicofluoride, zinc silicofluoride, ammonium silicofluoride, and one or more of these can be used. is there. Among these, sodium aluminum hexafluoride is preferable in terms of excellent setting properties.
The concentration of the fluorine compound in the liquid accelerator is preferably 0.1 to 10%, more preferably 1 to 8%. If it is less than 0.1%, the improvement of the setting property and initial strength development may be small, and if it exceeds 10%, the storage stability may be lowered or the long-term strength development may be inhibited.

The liquid accelerating agent of the present invention may contain alcohol amines. Alcohol amines are used for the purpose of improving the setting properties and initial strength development. The alcohol amine is not particularly limited as long as it is soluble in water or an acidic aqueous solution. Moreover, as long as it adds to a liquid and it becomes a uniform state, the order put in at the time of manufacture will not ask | require.
Alcoholamines are a general term for organic compounds having both an amino group and a hydroxyl group. Examples of alcohol amines include ethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, and the like, and one or more of these can be used. Among these, diethanolamine is preferable in that the setting property is excellent.
The concentration of alcohol amines in the liquid accelerator is preferably from 0.1 to 5%, more preferably from 0.5 to 3%. If it is less than 0.1%, the improvement of the setting properties and initial strength development may be small, and if it exceeds 5%, storage stability may be impaired or long-term strength development may be inhibited.

  The viscosity at 20 ° C. of the liquid quick setting agent of the present invention is preferably 300 to 5,000 mPa · s, and more preferably 500 to 2,000 mPa · s. If it is less than 300 mPa · s, insoluble particles may settle and may be easily separated. If it exceeds 5,000 mPa · s, the viscosity of the suspension is high and pumping may be difficult.

  In the cement composition of the present invention, the use amount of the liquid setting agent is preferably 3 to 20 parts, more preferably 5 to 15 parts, and most preferably 7 to 10 parts with respect to the cement part. If it is less than 3 parts, it may be difficult to promote rapid setting of the quick setting shotcrete, and if it is 20 parts or more, long-term strength development may be impaired.

  Here, the cement includes various ordinary Portland cements such as normal, early strength, medium heat, and ultra-early strength, and various mixed cements obtained by mixing these various Portland cements with fly ash, blast furnace slag, and the like. These can be used in the form of fine powder.

The cement concrete used in the present invention contains cement and aggregate. Here, as the aggregate, those having low water absorption and high aggregate strength are preferable. The maximum dimension of the aggregate is not particularly limited as long as it can be sprayed.
River sand, mountain sand, lime sand, and quartz sand can be used as the fine aggregate, and river gravel, mountain gravel, lime gravel, and the like can be used as the coarse aggregate.

  The amount of water used for the cement concrete is preferably 35% or more, more preferably 40 to 55% in terms of water / cement ratio in terms of strength development. If it is less than 35%, cement concrete may not be sufficiently mixed.

  The spraying method of the present invention is not particularly limited, but as a wet spraying method, for example, cement, fine aggregate, coarse aggregate, and water are added and mixed, pneumatically fed, in the middle There is a method in which a Y-shaped pipe is provided, and a quick setting wet spray concrete obtained by joining and mixing the quick setting agent pumped from one side by a quick setting agent supply device is used.

  Further, the pressure of the pumping air for pumping the quick setting agent may be 0.01 to 0.3 MPa higher than the pumping pressure of the concrete so that the concrete does not block when the concrete is mixed in the pumping pipe of the quick setting agent. preferable.

  Hereinafter, the present invention will be described in detail based on examples.

"Experiment 1"
Various liquid accelerating agents were prepared by adding aluminum sulfate and various cellulose ethers to water so as to have concentrations shown in Table 1 and stirring for 1 hour. Further, after stirring, the liquid was allowed to stand for 3 hours, and the viscosity was measured with a viscometer. Furthermore, the liquid was allowed to stand for 1 month, and the degree of separation was evaluated. The results are also shown in Table 1.

<Materials used>
Aluminum sulfate: Aluminum sulfate 14 hydrate, commercially available water-soluble cellulose ether (indicated as CE)
A: Methyl cellulose, average molecular weight 27,000
B: Hydroxyethyl cellulose, average molecular weight 34,000
C: Hydroxypropyl cellulose, average molecular weight 26,000
D: Hydroxypropyl methylcellulose, average molecular weight 32,000
E1: Carboxymethylcellulose, average molecular weight 7,000
E2: Carboxymethyl cellulose, average molecular weight 10,000
E3: Carboxymethyl cellulose, average molecular weight 15,000
E4: Carboxymethylcellulose, average molecular weight 33,000
E5: Carboxymethylcellulose, average molecular weight 50,000
E6: Carboxymethylcellulose, average molecular weight 73,000
E7: Carboxymethylcellulose, average molecular weight 100,000
E8: Carboxymethyl cellulose, average molecular weight 160,000
Accelerator: Aluminum hexafluoride sodium (A), diethanolamine (I), commercial product

<Measurement conditions>
Viscosity: Use a B-type viscometer (for example, Toki Sangyo TVB-10) Test environment temperature: set to 20 ° C. Separation degree: Evaluate volume ratio of transparent supernatant to total liquid with measuring cylinder ○: 0-5 %, Δ: 5 to 10%, x: more than 10%, *: no suspension phase (dissolution)

  From Table 1, it is desirable that the composition has an aluminum sulfate concentration of 30-50% and a water-soluble cellulose ether concentration of 0.01-5% as the viscosity of the liquid quick setting agent, and the degree of separation is low and the dispersibility is excellent. . Among water-soluble cellulose ethers, carboxymethyl cellulose is desirable. The average molecular weight of the water-soluble cellulose ether is preferably 10,000 to 100,000.

"Experiment 2"
As in Experimental Example 1, the aluminum sulfate concentration was 35%, the water-soluble cellulose ether concentration was 0.5%, and the accelerator (fluoride or alcohol amine) concentration was the value shown in Table 2. Various liquid accelerators were prepared, the viscosity was measured, and the degree of separation was evaluated.

<Materials used>
Aluminum sulfate: as in Experimental Example 1, water-soluble cellulose ether: carboxymethyl cellulose, average molecular weight 33,000
Accelerator (A): Sodium aluminum hexafluoride accelerator (I): Diethanolamine

From Table 2, it can be seen that the composition of an aluminum sulfate concentration of 35%, a water-soluble cellulose ether concentration of 0.5%, and a constant concentration of an accelerator (fluorine compound of 10% or less, alcohol amines of 5% or less) The viscosity of the agent is desirable, and the degree of separation is low and the dispersibility is excellent.

"Experiment 3"
As shown in Table 3, liquid quick setting agents having the formulations shown in Experimental Examples 1 and 2 were prepared. Further, the viscosity of the prepared liquid was measured at temperatures of −10, 20, and 40 ° C. in the same procedure as in Experimental Example 1, and the degree of separation was evaluated. The results are also shown in Table 3.

<Measurement conditions>
Viscosity: As in Experimental Example 1, degree of separation: volume ratio of transparent supernatant to the whole liquid was evaluated with a graduated cylinder ○: 0 to 5%, Δ: 5 to 10%, ×: more than 10%, *: suspension phase None (dissolution), **: liquid solidifies

From Table 3, the liquid quick setting agent having an aluminum sulfate concentration of 30 to 50% and a water-soluble cellulose ether concentration of 0.01 to 5% is at -10 to 40 ° C for at least one month after adjustment. , Low separation and excellent dispersibility. Furthermore, an aluminum sulfate concentration of 35%, a water-soluble cellulose ether concentration of 1%, a certain concentration of accelerator (fluorine compound concentration of 0.1 to 10%, or alcohol amine concentration of 0.1 to 5%) The liquid quick-setting agent contained is also excellent in storage stability under the same conditions.

"Experimental example 4"
In the same manner as in Experimental Example 1, aluminum sulfate and water-soluble cellulose ether were added to water so that the concentration of the liquid accelerating agent was a value shown in Table 4 to prepare a liquid accelerating agent. Also, a mortar having a sand / cement ratio = 3 and a water / cement ratio = 54% was prepared, and 7 parts of a liquid quick-setting agent was added to 100 parts of the cement to form a quick-setting mortar. Further, the compressive strength was measured. The results are also shown in Table 5.

<Materials used>
Cement: Ordinary Portland cement, commercial product, Blaine specific surface area 3,600 cm ² / g, specific gravity 3.16
Fine Aggregate: River sand from Himekawa, Itoigawa City, Niigata Prefecture, surface dry condition, specific gravity 2.62
Aluminum sulfate, water-soluble cellulose ether: as in Experimental Example 2

<Measurement method>
Setting test: Quick setting mortar measured in accordance with Japan Society of Civil Engineers standard "Quality standards for quick setting for sprayed concrete (JSCED-102)" Compressive strength: Quick setting mortar measured in accordance with JIS R 5201 Environmental test temperature: Set to 20 ° C

  From Table 4, it is desirable as the properties of the quick setting agent that the aluminum sulfate concentration is 30 to 50% and the water-soluble cellulose ether concentration is 0.01 to 5%.

“Experimental Example 5”
A liquid quick-set agent having a liquid quick-set concentration of 35% aluminum sulfate and 0.5% water-soluble cellulose ether was prepared. Also, a mortar similar to that of Experimental Example 4 was prepared, and with respect to 100 parts of the cement, a liquid quick-setting agent was added in an amount shown in Table 5 to form a quick-setting mortar, and the setting time was further increased in compression strength. It was measured. The results are also shown in Table 5.

  From Table 4, it is desirable as the property of the spray material that the addition amount of the quick setting agent is 3 to 20 parts with respect to 100 parts of cement.

"Experimental example 6"
As in Experimental Example 1, the liquid accelerator was prepared so that the concentration of aluminum sulfate was 35% and the concentration of the water-soluble cellulose ether was 1%. Further, as in Experimental Example 2, the types shown in Table 6 were prepared. And a liquid accelerator containing a concentration promoter. Further, a mortar similar to Experimental Example 4 was prepared, and 7 parts of a quick setting agent was added to 100 parts of the cement to obtain a quick setting mortar. The setting time and further compressive strength were measured. The liquid accelerator was used one week after production. The results are also shown in Table 6.

From Table 6, if the concentration of the fluorine compound in the liquid accelerator is 0.1 to 10% and the concentration of alcohol amines is 0.1 to 5%, the setting property is improved and the strength development is greatly impaired. Therefore, it is desirable as a property of the liquid setting agent.

  By using the liquid quick setting agent, the cement composition, and the spraying method using them according to the present invention, it has superior storage stability and fluidity compared to conventional quick setting agents, and further has high setting properties and strength development. Therefore, it can be used widely in the fields of civil engineering and architecture.

Claims (5)

And 30 to 50% by weight of aluminum sulfate, average molecular weight of 0.01 to 5% by weight to prepare a water-soluble cellulose ethers from 10,000 to 100,000, a mixture of water liquid quick-setting admixture And
In the temperature range of −10 to 40 ° C., the liquid accelerator is stored for a period of one month or more, insoluble particles are dispersed in the liquid, and 90% or more of the liquid is suspended by volume. Staying in condition
A method for preserving a liquid accelerating agent. The storage method according to claim 1 , wherein the liquid accelerator further contains a fluorine compound. The storage method according to claim 1 or 2 , wherein the liquid accelerator further contains alcohol amines. The storage method according to any one of claims 1 to 3 , wherein the liquid quick setting agent has a viscosity at 20 ° C of 300 to 5,000 mPa · s. A cement composition was prepared by adding 3 to 20 parts by mass of the liquid quick-setting agent stored by the storage method according to any one of claims 1 to 4 with respect to 100 parts by mass of cement, and the prepared cement Spraying method using the composition .