JP2000185952A - Liquid accelerator for cement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the quick setting property of a liquid accelerator for cement by specifying the molar ratio of Al2O3 component to SO3 component in an aqueous suspension mainly comprising Al2O3 and SO3 components. SOLUTION: This liquid accelerator for cement is an aqueous suspension mainly comprising Al2O3 and SO3, in which the molar ratio of (Al2O3/SO3) is 0.35-0.5 and both excellent initial quick setting property and excellent strength development are manifested. The liquid accelerator preferably consists of 8-15 wt.% Al2O3, 15-25 wt.% SO3 and water. When added with 1-15 wt.% SiO2 on top of that, adhesion to sprayed surfaces is improved, the initial strength of cement is increased and long-term strength is also augmented. When a particle diameter d(50) and d(90) both based on the cumulative size distribution of suspended particles in the aqueous suspension is 1-35 μm and 20-500 μm respectively, the suspension is preferably excellent in stability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid quick-setting agent used for spraying a cement-based material such as mortar or concrete onto a ceiling or a wall surface when constructing a tunnel or an underground structure.

[0002]

2. Description of the Related Art As a lining method for tunnels and underground structures, a spraying method using a quick-setting agent and compressed air to directly blow mortar or concrete onto a construction surface without using a formwork has been known. Have been. In this spraying method,
(a) cement, a concrete material consisting of fine aggregate and coarse aggregate, a quick setting agent is mixed in advance, and water is added to the mixed powder in front of the spray nozzle to spray as ready-mixed concrete, and (b) There is a wet method in which cement, fine aggregate, coarse aggregate and water are kneaded to prepare fresh concrete, to which a quick-setting agent is added in front of a spray nozzle. In any of the methods, powder quick-setting agents such as calcium aluminate and calcium sulfoaluminate have been used as the quick-setting agent. This quick-setting agent is scattered when added to concrete because it is a powder, it is difficult to add the required amount stably, and because it is not sufficiently mixed with concrete, it is sprayed. There is a problem that the hardened concrete body is likely to be heterogeneous. Further, there is a problem that a large amount of dust is generated due to the scattering of the powder quick-setting material, thereby deteriorating the working environment.

[0003] In order to solve these disadvantages, liquid type quick-setting agents comprising silica sol, aluminum-based compounds and the like have been devised. Since these quick-setting agents are liquid at the time of spraying construction, the required amount can be added stably without being scattered when added to concrete, so that the hardened concrete sprayed becomes homogeneous,
In addition, there is an advantage in that generation of dust is small and handling is easy. However, it is difficult to say that the quick setting performance of the current liquid type quick setting agent is sufficient.For practical use, the initial setting performance of the quick setting agent within several minutes after the quick setting agent is mixed with concrete. We needed to improve.

[0004]

An object of the present invention is to solve the above-mentioned problems in the conventional liquid quick-setting admixture, and to provide a liquid quick-setting admixture excellent in expression of initial strength.

[0005]

That is, the present invention provides:
(1) An aqueous suspension containing an Al ₂ O ₃ component and an SO ₃ component as main components, wherein the molar ratio (A / S ratio) between the Al ₂ O ₃ component and the SO ₃ component in the liquid is 0.1. The present invention relates to a liquid quick setting agent for cement, wherein the ratio is in the range of 35 ≦ A / S ratio ≦ 0.5. This liquid quick-setting agent has, for example, a specific component amount of (2) Al ₂ O ₃
8% to 15% by weight of the component and 1% of the SO ₃ component
It is preferable that the content is 5% by weight or more and 25% by weight or less, with the balance being water. When the Al ₂ O ₃ component and the SO ₃ component are within the above ranges, excellent initial quick-setting and strength can be exhibited.

Further, the above-mentioned liquid quick-setting agent of the present invention comprises (3)
An aqueous suspension containing an SiO ₂ component together with an Al ₂ O ₃ component and an SO ₃ component, wherein the aqueous suspension contains an Al ₂ O ₃ component and a SO ₃ component.
The molar ratio (A / S ratio) of the components is in the range of 0.35 ≦ A / S ratio ≦ 0.5. This liquid quick-setting agent has, for example, specific component amounts of (4) an Al ₂ O ₃ component of 8 wt% to 15 wt%, an SO ₃ component of 15 wt% to 25 wt%, SiO 2 ₂ components are 1 in anhydrous equivalent
It is preferable that the amount is not less than 15% by weight and not more than 15% by weight, with the balance being water. By containing the silica component, the adhesion to the sprayed surface is improved, and the initial strength of the cement is increased and the long-term strength is also enhanced.

Further, the liquid quick-setting admixture of the present invention has (5) a particle diameter d (50) according to the cumulative particle size distribution of the suspended particles in the aqueous suspension of 1 to 35 μm, and a particle size d ( 90) is 2
Those having a thickness of 0 to 500 μm are preferred. When the suspended particles are within the above range, the dispersibility of the particles is maintained well, and the stability as an aqueous suspension is excellent.

Further, the above-mentioned liquid quick-setting agent of the present invention comprises (6)
Aluminum sulfate as an Al ₂ O ₃ component and an SO ₃ component, wherein the content of the aluminum sulfate is not less than the solubility and not more than 1.5 times the solubility in terms of anhydrous content and contains undissolved aluminum sulfate particles. including. Also,
(7) Includes those containing amines as stabilizers. An aqueous suspension having an appropriate A / S ratio can be obtained by using aluminum sulfate having a solubility or higher, and the stability of the suspension is further improved by containing amines.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to embodiments. The liquid quick-setting admixture of the present invention comprises an Al ₂ O ₃ component and an SO ₃ component as main components, preferably silica (Si
An aqueous suspension containing (Al ₂ O ₂ component)
The molar ratio (A / S ratio) of the O ₃ component and the SO ₃ component is 0.35 ≦ A / S
The ratio is within the range of 0.5.

The Al ₂ O ₃ component in the liquid quick setting agent of the present invention is contained as aluminum ions dissolved in the liquid,
Also included as suspended particles such as alumina (Al ₂ O ₃ ) particles, aluminum hydroxide [Al (OH) ₃ ] particles, and aluminum sulfate hydrate particles dispersed in the liquid. Specifically, aluminum sulfate, aluminum nitrate, water-soluble aluminum salts such as sodium aluminate, aluminum hydroxide, activated alumina, aluminum compounds such as alumina gel, alums, metakaolin, raw materials containing aluminum such as acid clay and the like; It is supplied from a mixture or the like. The SO ₃ component is supplied from a sulfate such as aluminum sulfate, magnesium sulfate, sodium sulfate, and calcium sulfate. Aluminum sulfate is preferred as having both the Al ₂ O ₃ component and the SO ₃ component.

The liquid quick setting agent of the present invention has a molar ratio of Al ₂ O ₃ component to SO ₃ component (Al ₂ O ₃ component / SO ₃ component, abbreviated as A / S ratio) of 0.35 ≦. The A / S ratio was adjusted to be within a range of 0.5. If the molar ratio is less than 0.35, the quick setting property is low, and if it exceeds 0.5, the manifestation of the initial strength of the cement from several tens of minutes to several tens of hours is reduced, and the stability as a liquid is impaired. The stability deteriorates. As for the amount of each component, the Al ₂ O ₃ component is not less than 8% by weight and not more than 15% by weight,
The O ₃ component is preferably from 15% by weight to 25% by weight.

When aluminum sulfate is used as the Al ₂ O ₃ component and the SO ₃ component, the content of aluminum sulfate in terms of anhydrous is not less than solubility and not more than 1.5 times the solubility, preferably not less than solubility and not more than 1.5 times. .25 times or less is appropriate. By using aluminum sulfate in this concentration range, an aqueous suspension containing undissolved aluminum sulfate hydrate particles as suspended particles is obtained. In this case, Al
The amount ratio of the ₂ O ₃ component to the SO ₃ component is an oxide conversion ratio containing both undissolved aluminum sulfate hydrate particles and dissolved aluminum sulfate in the liquid. Since the A / S ratio of aluminum sulfate is about 0.33, if it is used alone, it falls outside the range of the A / S ratio of the present invention. Therefore, when aluminum sulfate is used, the molar ratio is adjusted by, for example, supplementing the Al ₂ O ₃ component separately so as to be within the above-mentioned A / S molar ratio.

If the equivalent amount of aluminum sulfate in the aqueous suspension is smaller than its solubility, sufficient initial curing performance cannot be obtained. On the other hand, when the equivalent amount of aluminum sulfate is much larger than 1.5 times the solubility, the initial curing performance is improved, but the stability of the aqueous suspension is gradually impaired, and a precipitate is formed. There is a risk of clogging the pump and the liquid feed pipe. By the way, the solubility of aluminum sulfate in water at 25 ° C. is 38.5 g / 100 g water (physical science dictionary) in terms of anhydrous, and the performance is improved by containing more aluminum sulfate component.

The liquid quick setting agent of the present invention preferably contains silica particles (SiO ₂ component). When the silica particles are added to the mortar or concrete, the gelation proceeds rapidly, giving the mortar or concrete stickiness,
Improves adhesion to the spray surface. In addition, it promotes the hydration of the alite component or belite component in the cement for several hours, increases the initial strength, and effectively increases the long-term strength.

The content of the above silica component is suitably from 1% by weight to 15% by weight, preferably from 3% to 10% by weight, calculated as anhydrous, based on the total weight of the quick setting agent. If the amount is less than 1% by weight, the effect of the addition is not recognized. If it exceeds 15% by weight, the content of other active ingredients is relatively restricted, the quick-setting property is reduced, and the viscosity of the liquid is high. It is not preferable because it becomes too much.

The above-mentioned silica component is supplied from silica compounds such as silica powder, silica fume, precipitated silica, aluminosilicate, smectite or smectite-type magnesium silicate, and a mixture thereof. Of these, precipitated silica is preferred. Precipitated silica is a precipitate of silica formed by reacting an alkali metal silicate with an acid (generally an inorganic acid), and easily exhibits the above-mentioned effects of silica.

The liquid quick setting agent of the present invention is an aqueous suspension,
The suspension particles include various suspension particles such as alumina particles, aluminum hydroxide particles, aluminum sulfate hydrate particles, and silica particles. These particles are partially aggregated and dispersed in the liquid. The particle size of these suspended particles is preferably from 1 to 35 μm according to the cumulative particle size distribution, and preferably from 20 to 500 μm according to the cumulative particle size distribution. The particle size d (50) in the cumulative particle size distribution means a particle size having a cumulative value of 50% by weight in the cumulative particle size distribution of the dispersed particles starting from the smaller particle size. Similarly, the particle size d (90) according to the cumulative particle size distribution means a particle size having a cumulative value of 90% by weight in the cumulative particle size distribution of particles having a smaller particle size. These particle sizes can be measured by laser scattering on a Cirrus particle size analyzer. When the suspended particles are within the above range, the dispersibility of the particles is ensured, and the stability as an aqueous suspension is excellent.

The liquid quick-setting admixture of the present invention comprises each of the Al ₂ O ₃ components, S
It is preferable to contain amines together with the O ₃ component and the SiO ₂ component. Amines in the aqueous suspension,
Suppress the precipitation and separation of aluminum component,
It has the effect of increasing the stability of the aqueous suspension. As the amines, either one of an aliphatic amine and an aromatic amine, or a mixture of both can be used. In addition, it is preferable that at least an aliphatic amine is contained, and among the aliphatic amines, an alkanolamine is more preferable. The alkanolamine preferably contains at least one of monoethanolamine, diethanolamine and triethanolamine. These alkanolamines further contribute to improving the stability of the aqueous suspension.

The content of the above amines is preferably from 0.1 to 10% by weight in the liquid quick-setting admixture, and from 0.2 to 8% by weight.
% By weight is particularly preferred. When the content of the amines is less than 0.1% by weight, the effect of adding the amines is insufficient. On the other hand, when the content is more than 10% by weight, the medium-to-long-term strength of the concrete may be adversely affected. In addition to the above-mentioned components, the liquid quick-setting admixture does not hinder the inclusion of a generally known organic dispersant within a range that does not impair the stability of the liquid.

The above-mentioned liquid quick-setting admixture of the present invention is used by spraying a kneaded cement mortar or concrete by adding a predetermined amount to these cement materials before the spray nozzle. The type of cement of the spray material is not limited. Portland cements such as ordinary Portland cement and early-strength Portland cement, and mixed cements such as blast furnace cement, silica cement, and fly ash cement can be widely used. Cement materials include cement dispersants such as water reducing agents and AE water reducing agents, admixtures such as thickeners, admixtures such as silica fume, fly ash and limestone fine powder, and various fiber materials. There may be.

[0021]

Examples and Comparative Examples Hereinafter, the present invention will be specifically described with reference to Examples. Note that these examples do not limit the present invention.

Example 1 and Comparative Example 1 At room temperature of 25 ° C., respective quick-setting agents A to G comprising aqueous suspensions having the formulations shown in Table 1 were prepared. With respect to the quick setting agent C shown in Table 1, quick setting agents I to which amines were added thereto were used.
M was adjusted (Table 2). As these raw materials, aluminum sulfate, activated alumina (γ-alumina type) and precipitated silica were used. The concentration of aluminum sulfate of the quick setting agent (AM) is higher than its solubility at 25 ° C. of 38.5 g / 100 g water, and is an aqueous suspension in which undissolved aluminum sulfate particles are suspended in the liquid. . The aluminum sulfate particles were confirmed by observation with a polarizing microscope.

[0023]

[Table 1]

[0024]

[Table 2]

Example 2 and Comparative Example 2 A stability test was carried out for each of the quick setting agents shown in Tables 1 and 2. The stability test was performed by the following accelerated test. First,
500 ml of each liquid quick-setting agent was placed in a transparent plastic container and stored in a device capable of controlling the temperature. Next, the temperature in the apparatus was lowered to 0 ° C. and maintained for 6 hours.
It was kept at 0 ° C. for 6 hours. Thereafter, the temperature was lowered to 0 ° C. over 6 hours. With this as one cycle, the test was continued for 1 to 3 months, and the properties of each quick-setting preparation after 1 month and 3 months were observed. Table 3 shows the results.

[0026]

[Table 3]

Example 3 and Comparative Example 3 Using each of the quick setting agents shown in Tables 1 and 2, concrete having the composition shown in Table 4 was produced and subjected to a spraying test. In this test, kneaded concrete spraying material was pumped by a pump, and a quick setting agent was applied to cement 3 m before the spraying nozzle.
% By weight and sprayed on a pull-out test formwork and a wooden formwork. As an evaluation of the hardening performance of the sprayed concrete, a pull-out test was conducted on the 3-hour and 24-hour materials after the completion of setting, and the compressive strength test was performed on a 28-year-old material and a 91-day-old material using a wooden mold. The test was performed on a test piece (diameter: 50 mm × length: 100 mm) obtained by core removal from the frame test piece. The spraying properties after the addition of the quick setting agent were evaluated visually and by touch. The results are shown in Table 5. As shown in Table 5, each of the examples of the present invention exhibited a good spraying condition and excellent quick-setting properties. On the other hand, the quick setting property of Comparative Example H was good, but the quick setting properties of Comparative Examples G and M were poor. Further, in the strength test, the examples of the present invention were all 3
High time strength and good quick setting. On the other hand, Comparative Example G
Is lower in intensity for 3 hours, and Comparative Example H is 3 hours in intensity and 24 hours.
The time intensity tended to be low. The strength of Comparative Example M was low throughout all ages.

[0028]

[Table 4]

[0029]

[Table 5]

[0030]

By using the quick-setting agent of the present invention in a cement-based spraying material such as mortar or concrete, it is possible to obtain excellent effects of quick-setting and strength.
Further, it has excellent stability as a liquid, and can be stored for a long time. Furthermore, since it is a liquid, there is little dust at the time of use, and deterioration of the working environment can be avoided.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C04B 103: 12 (72) Inventor Kumiko Kobayashi 2-4-2 Daisaku, Sakura City, Chiba Prefecture Pacific Cement Co., Ltd. (72) Inventor Koichi Soeda 2-4-2 Daisaku, Sakura City, Chiba Prefecture Pacific Sailing Cement Co., Ltd.

Claims (7)

[Claims] An aqueous suspension containing an Al ₂ O ₃ component and an SO ₃ component as main components, wherein the aqueous suspension contains an Al ₂ O ₃ component and an SO ₃ component.
A liquid quick setting agent for cement, wherein the molar ratio (A / S ratio) of the components is in the range of 0.35 ≦ A / S ratio ≦ 0.5. 2. The method according to claim 1, wherein the Al ₂ O ₃ component is at least 8% by weight to 15% by weight, the SO ₃ component is at least 15% by weight to 25% by weight, and the balance is water. Liquid quick setting agent for cement as described in 1). _3. S together with an Al ₂ O ₃ component and an SO ₃ component.
An aqueous suspension containing an iO ₂ component, wherein an Al ₂
The molar ratio (A / S ratio) of the O ₃ component and the SO ₃ component is 0.35 ≦ A / S
3. The liquid quick setting agent for cement according to claim 1, wherein the ratio is in a range of 0.5. 4. An Al ₂ O ₃ component of 8% to 15% by weight, an SO ₃ component of 15% to 25% by weight, and a SiO ₂ component of 1% to 15% by weight in terms of anhydrous. The liquid quick setting agent for cement according to claim 1, 2 or 3, wherein the remainder is water. 5. The particle size d (50) according to the cumulative particle size distribution of the suspended particles in the aqueous suspension is from 1 to 35 μm, and the particle size d (90) according to the cumulative particle size distribution is from 20 to 500 μm. The liquid quick setting agent for cement according to any one of claims 1 to 4. 6. An undissolved aluminum sulfate, wherein aluminum sulfate is used as the Al ₂ O ₃ component and the SO ₃ component, and the content of the aluminum sulfate is not less than solubility and not more than 1.5 times the solubility in terms of anhydrous. The liquid quick-setting agent for cement according to any one of claims 1 to 5, comprising particles. 7. The liquid quick setting agent for cement according to claim 1, which contains an amine as a stabilizer.