JP2014152057A - Liquid quick setting agent, cement composition using the same, and spraying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a liquid quick setting agent that is excellent in storage stability and fluidity and that exhibits effects such as improvement of the quick setting and the strength development, compared to a conventional liquid quick setting agent that uses aluminum sulfate; a cement composition using the same; and a spraying method.SOLUTION: In a liquid quick setting agent that contains aluminum sulfate and melamine-based dispersant and in which, at -10 to 40°C, 90% or more, in volume ratio, of the liquid is suspended uniformly, the aluminum sulfate concentration is 30 to 50 mass% and the melanine-based dispersant concentration is 0.01 to 5 mass%, a fluorine compound is contained, alcohol amines are contained, and further carboxylic acids are contained. A cement composition contains the liquid quick setting agent by 3 to 20 pts.mass for 100 pts.mass of cement and a spraying method uses the cement composition.

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 an excavation site, and cement, aggregate, and water are metered and mixed to adjust concrete for spraying, transported by an agitator car, and pumped by 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, it was not possible to obtain the desired properties, and improvements were necessary. 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 a high temperature or a low temperature.

Melamine dispersants are generally used as water reducing agents for concrete and mortar, and are added to concrete and mortar to control fluidity. Melamine-based dispersants are materials that impart dispersibility to concrete and mortar by adhering to the surface of cement particles, and are particularly effective for cement compositions with a low water / cement ratio and low fluidity. . When the quick setting agent is added to the cement composition, the fluidity decreases rapidly, so the quick setting agent and the cement composition may not be mixed well. Mixability of the quick setting agent and the cement composition is improved (Patent Document 7).
Thus, it is common to use a water reducing agent by adding it to a cement composition, and it relates to the development of a material added to a liquid accelerator containing aluminum sulfate and improvement of the storage stability of the liquid accelerator. There are no studies or examples of use as a liquid accelerator for concrete or mortar. In addition, there is no knowledge that the rapid setting property of the cement composition is improved by using the liquid quick setting agent containing the melamine dispersant. This is thought to be because the melamine-based dispersant contained in the liquid improves the fluidity when mixed with the cement composition and improves the mixability of the cement composition and the quick setting agent.

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 JP 2011-136886 A

As a result of various studies on the above problems, the present inventor has obtained knowledge to solve the problems by suppressing liquid gelation and suspended particle sedimentation by adding a melamine-based dispersant to the liquid quick setting agent. The invention has been completed.

  That is, the present invention includes (1) a liquid quick-setting agent containing aluminum sulfate and a melamine-based dispersant, wherein 90% or more of the liquid is uniformly suspended by volume at -10 to 40 ° C., (2) (1) Liquid quick setting agent whose aluminum sulfate concentration of liquid quick setting agent is 30-50 mass% and melamine type dispersing agent concentration is 0.01-5 mass%, (3) Furthermore, a fluorine compound is contained ( 1) or (2) liquid accelerator, (4) further containing alcohol amines (1) to (3) any of the liquid accelerators, (5) further containing carboxylic acids 3 to 20 parts by mass of any one of (1) to (4), or any one of (6) and (1) to (5). Part-containing cement composition, (7) spraying work using cement composition of (6) , It is.

  The liquid quick-setting agent of the present invention is superior in storage stability and fluidity compared to conventional liquid quick-setting agents. Furthermore, by using this liquid quick setting agent, the quick setting property and strength development property of the quick setting shot concrete are improved 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, “parts” 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 dispersibility in a liquid is excellent.
The concentration of aluminum sulfate in the liquid accelerator is preferably 30 to 50%, more preferably 33 to 40%. If it is less than 30%, excellent rapid setting may not be obtained when mixed with concrete, and if it exceeds 50%, the storage stability of the liquid may be impaired.

As the melamine dispersant used in the present invention, both powder and aqueous solution can be used, and commercially available ones can be used.
The concentration of the melamine dispersant in the liquid setting agent is preferably 0.01 to 5%, more preferably 0.1 to 3%. If it is less than 0.01%, the storage stability of the liquid may be impaired. If it exceeds 5%, strength development may be impaired when mixed with concrete.

Storage stability is an important property when pumping a liquid quick-set agent from a tank during spraying. If the liquid gels or the suspended particles settle, it may be difficult to discharge from the tank. Even if the particles can be discharged, if the suspended particles are settled, the concentration of the liquid quick-setting agent is not uniform, so that there may be unevenness in the setting properties and strength development properties of the sprayed concrete.
When the storage stability of the liquid setting agent of the present invention is evaluated by the degree of separation, it is preferably 10% or less, more preferably 5% or less. The degree of separation referred to here is the volume ratio of the supernatant liquid produced by sedimentation of suspended particles to the whole liquid, and the fact that the degree of separation is extremely small means that the liquid is uniform.

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.
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 0.3 to 7%. 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.
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 0.2 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 liquid accelerator of the present invention may contain carboxylic acids. Carboxylic acids are used for the purpose of improving storage stability. Carboxylic acids are not particularly limited as long as they are soluble in water or an acidic aqueous solution.
Carboxy is a general term for organic compounds having a carboxyl group. Carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, pentanoic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, oxalic acid, malonic acid, succinic acid, glutamic acid, adipic acid, fumaric acid, maleic acid, benzoic acid, Examples thereof include lactic acid, malic acid, citric acid, salicylic acid, and the like, and sodium salts or potassium salts thereof, and one or more of these can be used. Among these, oxalic acid is preferable in terms of excellent storage stability.
The concentration of the carboxylic acids in the liquid accelerator 100 is preferably 0.1 to 3%, more preferably 0.2 to 2%. If it is less than 0.1%, the improvement in storage stability may be small, and if it exceeds 3%, strength development may be inhibited.

  In the cement composition of the present invention, the amount of the liquid quick-setting agent is preferably 3 to 20 parts, more preferably 5 to 15 parts, and most preferably 7 to 10 parts with respect to 100 parts of cement. If it is less than 3 parts, it may be difficult to promote the quick setting property of the quick setting shot concrete, and if it exceeds 20 parts, 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 accelerators were prepared by adding aluminum sulfate and a melamine dispersant 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 and the degree of separation of the liquid was evaluated. The results are also shown in Table 1.

<Materials used>
Aluminum sulfate: Aluminum sulfate 14 hydrate, powder, commercially available melamine dispersant A: manufactured by Grace Chemicals, trade name “FT-700N”, melamine sulfonate melamine dispersant B: manufactured by Nippon Sika Co., Ltd., trade name “ Seakament FF86 ", methylol melamine series

<Measurement conditions>
Test environment temperature: set to 20 ° C. Separation degree: The volume ratio of the suspension phase to the whole liquid is evaluated with a graduated cylinder. The degree of separation is the volume ratio of the supernatant produced by sedimentation of suspended particles to the total liquid.

  From Table 1, the liquid of the mixing | blending whose aluminum sulfate density | concentration is 30 to 50% and melamine type-dispersant density | concentration is 0.01 to 5% has a low degree of separation, and is desirable as the storage stability of a quick setting agent.

"Experimental example 2"
As in Experimental Example 1, the liquid accelerator has an aluminum sulfate concentration of 35%, a melamine dispersant A concentration of 1%, and auxiliary agents (fluorine compounds, alcohol amines, carvone so as to have the concentrations shown in Table 2. Acids) were added to water to prepare a liquid accelerator. Further, the degree of separation was evaluated in the same procedure as in Experimental Example 1. The results are also shown in Table 2.

<Materials used>
Auxiliary agent (A): Aluminum hexafluoride sodium, Commercial product auxiliary agent (I): Diethanolamine, Commercial product auxiliary agent (U): Oxalic acid, commercial item

From Table 2, if the concentration of the fluorine compound in the liquid accelerator is up to 10% and the concentration of alcoholamines is up to 5%, the degree of separation does not increase significantly. Moreover, if the density | concentration of carboxylic acid is 0.1% or more, a resolution will fall and the storage stability of a liquid quick-setting agent will improve.

"Experiment 3"
Liquid quick setting agents having the formulations shown in Experimental Example 1 and Experimental Example 2 were prepared. Further, the separation degree after 3 months was evaluated in the same procedure as in Experimental Example 1 at −5 ° C., 20 ° C., and 40 ° C. The results are also shown in Table 3.

From Table 3, the liquid quick-setting agent whose concentration of aluminum sulfate in the liquid quick-setting agent is 30 to 50% and the concentration of melamine-based dispersant is 0.01 to 5% is at -5 to 40 ° C for at least 3 months. The degree of separation is small, 90% or more of the liquid is uniform, and the storage stability is excellent.
Furthermore, the concentration of aluminum sulfate is 35%, the concentration of melamine-based dispersant is 1%, the aid of a certain concentration (fluorine compound concentration is 0.1 to 10%, or the concentration of alcohol amines is 0.1 to 0.1%. A liquid accelerator containing 5% or a carboxylic acid concentration of 0.1 to 3% 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 a melamine dispersant 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 cement to obtain a quick setting mortar. The compressive strength was measured. The liquid accelerator was used one week after production. The results are also shown in Table 4.

<Materials used>
Cement: Ordinary Portland cement, commercial product, Blaine specific surface area 3,800 cm ² / g, specific gravity 3.16
Fine aggregate: Niigata prefecture Itoigawa city Himekawa production river sand, surface dry state, specific gravity 2.62, 5mm vulgar

<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 parts and the melamine dispersant concentration is 0.01 to 5 parts.

“Experimental Example 5”
A liquid quick-set agent having a liquid quick-set concentration of 35% aluminum sulfate and 1% melamine dispersant was prepared. In addition, a mortar similar to that in Experimental Example 4 was prepared, and a liquid quick setting agent was added in an amount shown in Table 5 to 100 parts of cement to form a quick setting mortar. The setting time was further measured and the compressive strength was measured. did. The liquid accelerator was used one week after production. The results are also shown in Table 5.

  From Table 5, the addition amount of the quick setting agent is desirably 3 to 20 parts with respect to 100 parts of cement as the properties of the spray material.

"Experimental example 6"
In the same manner as in Experimental Example 1, a liquid accelerator containing 35% of the concentration of aluminum sulfate in the liquid accelerator, 1% of the concentration of the melamine dispersant, and the type and concentration of auxiliary agents shown in Table 6 was prepared. . Moreover, the same mortar as Experimental example 4 was prepared, 7 parts of quick setting agents were added with respect to 100 parts of cement, it was set as the quick setting mortar, the setting time, and also the compressive strength were measured. The liquid accelerator was used one week after production. The results are also shown in Table 6.

<Materials used>
Aluminum sulfate, melamine dispersant, auxiliaries: Same as “Experiment 2” Cement, fine aggregate: Same as “Experiment 4”

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. Since it does not occur, it is desirable as a property of the quick setting agent. Further, if the concentration of the carboxylic acid is 3% or less, the setting property and strength development property are not greatly impaired, and thus it is desirable as the property of the quick setting agent.

  The liquid accelerating agent of the present invention has been solved to suppress the gelation of liquid and sedimentation of suspended particles, which are problems with the aluminum sulfate liquid accelerating agent, and to have excellent storage stability. Further, the spraying method used in combination with the cement composition can increase the setting property and the strength development, so that it can be widely used in the fields of civil engineering and construction.

Claims (7)

A liquid accelerating agent comprising aluminum sulfate and a melamine-based dispersant, wherein 90% or more of the liquid is suspended by volume at -10 to 40 ° C. The liquid quick setting agent according to claim 1, wherein the liquid quick setting agent has an aluminum sulfate concentration of 30 to 50 mass% and a melamine dispersant concentration of 0.01 to 5 mass%. Furthermore, the liquid quick setting agent of Claim 1 or 2 containing a fluorine compound. Furthermore, alcohol amines are contained, The liquid quick setting agent of any one of Claims 1-3 characterized by the above-mentioned. Furthermore, carboxylic acid is contained, The liquid quick setting agent of any one of Claims 1-4 characterized by the above-mentioned. A cement composition comprising 3 to 20 parts by mass of the liquid quick setting agent according to any one of claims 1 to 5 with respect to 100 parts by mass of cement. A spraying method using the cement composition according to claim 6.