JP2006151760A - Liquid quick setting agent for mortar or concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid quick setting agent by which quick setting property direct after spraying is kept to be capable of thick coating, following setting acceleration is suppressed to secure working time for leveling or the like. <P>SOLUTION: The liquid quick setting agent for mortar or concrete contains 100 pts.wt. calcium aluminate having the molar ratio CaO/Al<SB>2</SB>O<SB>3</SB>of ≥1.5 and ≥4,000 cm<SP>2</SP>/g Blaine specific surface area and 30-100 pts.wt. liquid oil keeping a liquid state at least at 20°C. A mortar or concrete composition contains base mortar or base concrete and the liquid quick setting agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid quick setting agent for mortar or concrete which is mixed with base mortar or base concrete to suppress the generation of dust during spraying and the acceleration of hardening after 30 seconds from the time of spraying.

  In the construction of sprayed mortar or shotcrete, it may be necessary to level the surface with a trowel after spraying. At this time, if the shotcrete has a high quick setting property, it is hardened quickly, and the time required for the leveling work cannot be secured. In order to secure time for the leveling work, it is necessary to suppress (decrease) quick setting. However, when the quick setting property is lowered, the spraying thickness of concrete or mortar that can be sprayed at a time becomes thin. In particular, in the ceiling portion of a tunnel or the like, when spraying is performed with reduced quick setting, there is a problem that the loss due to its own weight becomes a problem as the thickness of the spray increases, and the material loss becomes very large.

  Conventionally, as a calcium aluminate-based quick setting agent for spray mortar or shotcrete, powder is well known (for example, see Patent Document 1). However, although the powder calcium aluminate-based powder rapid setting agent has high quick setting immediately after spraying (within 30 seconds), it generates dust during spraying and cures after 30 seconds from spraying. It was impossible to suppress the promotion.

  In order to solve the above-mentioned problems, a slurry-like rapid suspending agent in which a calcium aluminate rapid suspending agent is suspended in water is known (for example, see Patent Document 2). When using a slurry-like accelerating agent, it is possible to suppress the generation of dust during spraying while maintaining the quick setting immediately after spraying, but to suppress hardening acceleration after 30 seconds from the time of spraying. I couldn't.

Therefore, a cement quick-setting agent is proposed to reduce the rebound when sprayed concrete is added by adding a very small amount of fatty acids (less than 5% of the quick-setting component) to the quick-setting component such as calcium aluminate. (See Patent Document 3).
JP 2000-233955 A JP 2000-302504 A JP 2002-53356 A

However, even if the quick setting agent is used, it maintains the quick setting necessary for shotcrete, suppresses the acceleration of hardening after 30 seconds from the time of spraying, and secures work time such as surface leveling. It ’s difficult. On the other hand, in the quick setting agent containing 5% or more fatty acids, the viscosity of the quick setting component becomes high, the supply of the quick setting agent becomes very difficult, and the calcium aluminate grows to form a strong bonded body. Even if formed and sprayed using compressed air in spraying construction, it does not disperse and good quick setting properties cannot be obtained.
Accordingly, the present invention enables thickening while maintaining quick setting immediately after spraying, suppresses acceleration of curing after 30 seconds from the time of spraying, and ensures work time for surface leveling and the like. An object of the present invention is to provide a liquid quick setting agent.

As a result of earnest research to solve the above problems, the present inventor has formulated calcium aluminate whose surface is coated with liquid oil by blending a specific amount of calcium aluminate with a specific amount of liquid oil in combination. Found that the liquid quick-setting agent contained can maintain the quick setting immediately after spraying, enables thickening, suppresses subsequent hardening acceleration, and secures work time such as surface leveling, and completes the present invention. did.
That is, the present invention relates to 100 parts by weight of calcium aluminate having a CaO / Al ₂ O ₃ molar ratio of 1.5 or more and a Blaine specific surface area of 4000 cm ² / g or more, and a liquid oil 30 that is liquid at least at 20 ° C. The liquid quick setting agent for mortar or concrete containing -100 weight part is provided.

  Moreover, this invention provides the mortar or concrete composition containing base mortar or base concrete and said liquid quick setting agent.

  Since the quick setting agent of the present invention is in a liquid state, it does not scatter and become a source of dust generation, has high quick setting immediately after spraying, can be thickened, and temporarily suppresses the subsequent hardening. Therefore, it is possible to ensure work time such as surface leveling. Therefore, the liquid quick setting agent of the present invention is useful for spray construction.

The calcium aluminate used in the liquid quick setting agent of the present invention imparts quick setting properties to mortar or concrete. “Calcium aluminate” is a general term for a compound, a solid solution, a vitreous substance, or a mixture thereof containing at least CaO and Al ₂ O ₃ as main components. The calcium aluminate used in the present invention has a CaO / Al ₂ O ₃ molar ratio of 1.5 or more and a Blaine specific surface area from the point of imparting quick setting immediately after spraying (within 30 seconds). It is 4000 cm ² / g or more. The molar ratio of CaO / Al ₂ O ₃ is preferably 1.5 to 3.0. The brain specific surface area is preferably 4000 to 5500 cm ² / g. Examples of such calcium aluminate include C ₁₂ A ₇ (12CaO · 7Al ₂ O ₃ ), C ₃ A (3CaO · Al ₂ O ₃ ), C ₁₁ A ₇ · CaF ₂ (11CaO · 7Al ₂ O ₃ · CaF ₂ ), NC ₈ A ₃ (Na ₂ O.8CaO.3Al ₂ O ₃ ) and the like. If the molar ratio of total CaO / Al ₂ O ₃ is 1.5 or more, Irwin _{(3CaO · 3Al 2 O 3 ·} CaSO 4) and _{CA (CaO · Al 2 O 3} ) and CA ₂ (CaO · 2Al ₂ O ₃ ) can also be used as part. A known apparatus such as an electric furnace or kiln can be used for firing the calcium aluminate. A normal pulverizer can be used for pulverization.

  The liquid oil used in the liquid quick setting agent of the present invention may be liquid at a normal temperature during spraying, that is, at least 20 ° C. In consideration of use in a cold region or winter, a liquid that is liquid even at a low temperature of about 10 ° C. is preferable. In addition, the liquid oil preferably has no volatility and a relatively high ignition temperature from the viewpoint of use in a closed space such as a tunnel and civil engineering work. Examples of such liquid oils include higher fatty acids, higher fatty acid esters, fats and oils, and mineral oils. Among these, unsaturated higher fatty acids such as oleic acid, vaccenic acid, linoleic acid, α-linolenic acid, γ-linolenic acid and arachidonic acid; esters of these unsaturated higher fatty acids; fats and oils containing unsaturated higher fatty acids as constituent fatty acids; Mineral oil such as liquid paraffin is preferable. From the point of high boiling point and flash point, fats and oils containing unsaturated higher fatty acids as unsaturated higher fatty acids or constituent fatty acids are more preferred. Note that stearic acid, which is a saturated higher fatty acid, has a high melting point, and if the liquid quick-setting agent contains a large amount of stearic acid, it may not be liquid at room temperature, which is not preferable.

  As fats and oils containing unsaturated higher fatty acids as constituent fatty acids, fats and oils containing 70% by weight or more of unsaturated higher fatty acids as constituent fatty acids are preferred, and specific examples include vegetable oils such as rapeseed oil and soybean oil. The viscosity of these vegetable oils is particularly suitable for spraying construction.

  The content of water in the liquid oil is preferably 1% or less, and more preferably contains no water. If water is contained, water reacts with calcium aluminate, which may reduce the quick setting property and may cure the liquid quick setting agent itself.

  By previously mixing the liquid oil and the calcium aluminate, scattering of the calcium aluminate during spraying can be prevented, and dust generation can be suppressed. In addition, a liquid oil film is formed on the surface of the calcium aluminate particles, the contact between the calcium aluminate and water is controlled, and the hydration of the calcium aluminate after 30 seconds from the time of spraying is temporarily suppressed. It is possible to secure work time such as leveling. In addition, suppression of hydration is temporary, and does not have a great influence on the subsequent short to long-term strength development.

  It is not preferable to add liquid oil directly to base mortar or base concrete in normal construction. Since a liquid oil film is not formed on the surface of the calcium aluminate particles, an appropriate hydration inhibiting effect cannot be obtained. Further, the liquid oil separates and floats on the surface together with the bleeding water, resulting in defects at the time of joining, and the adhesion strength at the joining part may be reduced. However, in the spray construction using the quick setting agent, since the curing starts immediately after spraying, the liquid oil is not separated and a uniform cured body can be obtained. In addition, since the liquid quick setting agent is blown away using compressed air in the spraying construction, the liquid oil does not remain as a large lump in the cured body, and it exists in a finely dispersed state, which can be a major defect. Absent.

  The compounding quantity of liquid oil is 30-100 weight part with respect to 100 weight part of calcium aluminates, 40-90 weight part is preferable, and 50-80 weight part is especially preferable. If it is less than 30 parts by weight, it becomes difficult to pump the liquid quick-setting agent with a liquid pump, the viscosity of the quick-setting agent itself increases, and dispersion into the base concrete or base mortar during spraying is not possible. It becomes insufficient and the desired quick setting property cannot be obtained. Moreover, when it exceeds 100 weight part, since solid-liquid separation will arise and the composition of liquid quick-setting agent itself supplied at the time of construction may vary, it is unpreferable.

  In the liquid quick setting agent of the present invention, various additives usually used for cement and concrete may be further blended within a range that does not inhibit the curability of mortar and concrete. Such additives include alkali metal or alkaline earth metal sulfates, alkali metal or alkaline earth metal carbonates, dispersants, antifoaming agents, AE agents, thickeners, silica fume, limestone fine powder, Examples include blast furnace slag fine powder, fly ash, and quartzite powder.

  In the production of the liquid quick-setting agent of the present invention, any mixer that can be usually used can be used. For example, in addition to a pan type mixer and a biaxial forced kneading mixer, various hand mixers can be used.

  As for content of the said liquid quick setting agent in the mortar or concrete composition of this invention, 2-15 weight part is preferable with respect to 100 weight part of base mortar or base concrete.

  The base mortar or the base concrete is not particularly limited and any one can be used. Moreover, even if it is different from general mortar or concrete such as fireproof covering material, waterproof material, etc., if it contains Portland cement or mixed cement in it, the base mortar for liquid quick setting agent of the present invention or Can be used as base concrete.

  As the Portland cement, any of ordinary, early strength, very early strength, moderate heat, low heat, sulfate resistance, etc. can be used. As the mixed cement, blast furnace cement, fly ash cement, or the like can be used. Further, cement obtained by replacing part of Portland cement or mixed cement with limestone powder or silica fume, cement obtained by adding gypsum to Portland cement or mixed cement, and the like can also be used. Two or more selected from Portland cement and mixed cement may be used in combination. From the viewpoint of quick setting, Portland cement is preferable, and ordinary Portland cement, early-strength Portland cement or white Portland cement, particularly early-strength Portland cement or white Portland cement is preferable.

  A water reducing agent can be blended in the base mortar or the base concrete. Examples of the water reducing agent include high performance water reducing agents (including high performance AE water reducing agents) such as alkylallyl sulfonic acid, naphthalene sulfonic acid, melamine sulfonic acid, and polycarboxylic acid. These may be either liquid or powder.

  Further, the base mortar or the base concrete can be mixed with an ordinary mortar or concrete admixture such as a thickener, an AE agent and an antifoaming agent. However, methylcellulose-based thickeners are not preferred because they inhibit the rapid setting of calcium aluminate.

  Examples of the fine aggregate include river sand, sea sand, mountain sand, crushed sand, and a mixture thereof. Examples of the coarse aggregate include river gravel, sea gravel, crushed stone, and a mixture thereof.

  The production method of the base mortar or the base concrete is not particularly limited, and each material may be mixed with a conventional mixer installed in a ready-mixed factory or a construction site.

  As a method for constructing shotcrete, a conventional wet method can be arbitrarily used. The dry method is not preferable in terms of dust generation. As the spraying device and the quick-setting agent addition device, a known device for the liquid quick-setting agent can be arbitrarily used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

[Materials used]
1. Base cement paste or base mortar (1) Cement; Ordinary Portland cement (manufactured by Taiheiyo Cement)
(2) High performance water reducing agent; Mighty 100 (manufactured by Kao Corporation)
(3) Fine aggregate: Crushed sand from Kokura Minami-ku, Kitakyushu City (specific gravity: 2.69): Sea sand off the coast of Noura, Iki-gun, Nagasaki Prefecture (specific gravity: 2.59) = 3: 7 (weight ratio) mixed product (4) Water; tap water

2. Quick setting agent (1) Calcium aluminate A1; C ₁₂ A ₇ (manufactured by calcination at 1600 ° C. in an electric furnace followed by slow cooling. Glass content 0%. CaO / Al ₂ O ₃ molar ratio 1.7 Blaine specific surface area 5100 cm ² / g)
A2: CA glass (manufactured by firing at 1600 ° C. in an electric furnace and then rapidly cooling. Glass content 100%, CaO / Al ₂ O ₃ molar ratio 2.1, Blaine specific surface area 4500 cm ² / g)
A3; C ₁₂ A ₇ -CA (manufactured by firing in an electric furnace at 1600 ° C. and gradually cooling. Glass content 0%. CaO / Al ₂ O ₃ molar ratio 1.3. Blaine specific surface area 4900 cm ² / g)
A4; C ₁₂ A ₇ (manufactured by firing at 1600 ° C. in an electric furnace and then gradually cooling. Glass content 0%. CaO / Al ₂ O ₃ molar ratio 1.7. Blaine specific surface area 3500 cm ² / g)
(2) Liquid for quick setting agent addition;
B1; None B2; Tap water B3; Ethylene glycol (water content 0.0%)
B4: Diethylene glycol (water content 0.0%)
B5; rapeseed oil (unsaturated higher fatty acid content 83%, water content 0.0%)
B6; soybean oil (unsaturated higher fatty acid content 87%, water content 0.0%)
B7: Mixture of soybean oil and palm oil (unsaturated higher fatty acid content 72%, water content 0.0%)
B8; oleic acid (water content 0.0%)
B9: Linoleic acid (water content 0.0%)
(3) Other additives; lithium carbonate

[Manufacture of quick setting agent]
One kind of 5 kg selected from the liquids B1 to B10 is put into a pail can (capacity 18 liters), and while stirring with a hand mixer, calcium aluminate and other predetermined amounts of additives are added over 30 seconds. The sample was stirred for minutes.

[Evaluation of very early rapid setting and subsequent hardening acceleration]
500 g of the cement, 2 g of the high-performance water reducing agent and 180 g of water were put into a 500 cc polyethylene container, mixed for 1 minute with a hand mixer, and then allowed to stand for 30 minutes. After re-stirring this with a hand mixer for 1 minute, the quick setting agent was added and stirred for 5 seconds with a hand mixer to prepare a sample.
The initial rapid setting property was evaluated from the Procter penetration resistance value of the paste 30 seconds after the quick setting agent was charged in a test at 20 ° C. in a constant temperature room. Procter's needle has a cross-sectional area of 0.125 inch ² and is included in the Japanese Society of Civil Engineers Concrete Standard Specification “Quality Standards for Sprayed Concrete Quality (Draft)” Annex “Method for Measuring Setting Time of Mortar by Penetration Resistance” Procter penetration resistance value was measured according to the indicated method. In addition, by the same method, the Procter penetration resistance value of the paste at the time when 6 minutes passed after the rapid setting agent was added was measured, and the rate of increase ([measured value after 6 minutes−measured value after 30 seconds] / measured after 30 seconds) Value), the subsequent degree of curing acceleration was evaluated. The results are shown in Table 1.

[Evaluation of dust amount]
Each 1 kg of the quick setting agent was dropped from a height of 1 m, and the amount of dust was visually evaluated. The case where even a small amount of dust was observed was rated as x, and the case where dust generation was not observed at all was marked as ◯. The results are shown in Table 1.

As is apparent from Table 1, when the liquid quick-setting agent of the present invention is used, no dust is generated, and the initial hardening (30 seconds value) is maintained, and the subsequent hardening is suppressed. It turns out that you can.
On the other hand, when the blending amount of the liquid oil is less than 30 parts by weight with respect to 100 parts by weight of calcium aluminate, it was not possible to suppress the subsequent hardening acceleration while maintaining the initial rapid setting property (comparison) Example 8).

[Spraying construction]
Pan mixer (Taiheiyokiko Co., capacitor 55 liters) to the cement 898kg / m ^3, sand 898kg / m ^3, a total of the proportions of superplasticizer 3.6 kg / m ³ and water 323 kg / m ³ 40 Each material was added so as to have a liter, and kneaded for 3 minutes to obtain a base mortar sample.
The liquid quick setting agent of Example 1 of Table 1 was added, and it sprayed toward the wall surface perpendicular | vertical to the ground of the L-type retaining wall in the simulated tunnel which was closed with the sheet | seat and was made into the windless state. The amount of spraying at one time was 40 liters, the spraying speed of base mortar was 8 liters / min, and the supply speed of the liquid quick setting agent was 0.4 liters / min. A new rotary pump manufactured by Okasan Kiko Co., Ltd. is used for pumping the base mortar, and a slavon manufactured by Taiheiyo Techno Co. is used for supplying the quick setting agent. The method for joining the base mortar sample and the liquid quick setting agent of Example 1 is Y The tube method was adopted.

  When the liquid quick-setting agent of the present invention was used, no dust was visually observed, and it was confirmed that thickening of 50 mm or more and subsequent surface finishing were possible at one time.

Claims (5)

100 parts by weight of calcium aluminate having a CaO / Al ₂ O ₃ molar ratio of 1.5 or more and a Blaine specific surface area of 4000 cm ² / g or more, and 30 to 100 parts by weight of liquid oil that is liquid at least at 20 ° C. Contains liquid quick setting agent for mortar or concrete. The liquid quick setting agent for mortar or concrete according to claim 1, wherein the molar ratio of CaO / Al ₂ O ₃ is 1.5 to 3.0.   The liquid quick setting agent for mortar or concrete according to claim 1 or 2, wherein the liquid oil contains 70% by weight or more of an unsaturated higher fatty acid.   A mortar or concrete composition containing base mortar or base concrete and the liquid quick setting agent according to any one of claims 1 to 3.   The mortar or concrete composition according to claim 4, which is used for spray construction.