JP2006083005A - Spray material and method for applying spray material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement-based spray material which can sufficiently suppress the generation of dust when it is sprayed, remarkably reduce the rebound generation rate and rapidly form a strong wall body surface not causing falling after it has been sprayed; and to provide a method for applying the same. <P>SOLUTION: The spray material comprises a slurry containing calcium aluminate, a dihydric lower alcohol, and an inorganic fine powder inactive to the dihydric lower alcohol and having a BET specific surface area of ≥10 m<SP>2</SP>/g and a slurry containing cement and water. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cement-based spraying material for spraying on the surface of a tunnel or a structure to form a strong wall surface and a method for applying the spraying material.

  Cement-based spraying materials used in tunnels and structures contain rapid hardening components such as calcium aluminate, sodium aluminate, and aluminum sulfate for imparting rapid setting properties to cement as a binder phase. If water is added to this formulation as it is, it will rapidly condense immediately after pouring, so it cannot be pre-prepared and kneaded, and it will need to be sprayed immediately after pouring, resulting in great restrictions in actual work. . For this reason, the quick-hardening component and the kneaded product in which water is added to the other components are separated and adjusted, and both of them are mixed immediately before spraying to greatly reduce work restrictions. Ensuring stable quality has been done. On the other hand, when such a spraying material is sprayed, a large amount of rebounding (rebound) occurs, and the amount of the spraying material that is wasted is not unusual. As a method for suppressing the occurrence of rebound, it is also known to use inorganic fine powders such as silica fume and graphite in addition to the rapid hardening component. (For example, refer to Patent Document 1.)

However, when inorganic fine powder is added to the cement kneaded material to which water has been added, the viscosity may increase so as to hinder the workability. . On the other hand, when an inorganic fine powder is added and blended on the quick-hardening component side, the inorganic fine powder is scattered and floated especially during construction, and easily becomes dusty. Dust generation can be prevented by using a liquefied quick-hardening component (see, for example, Patent Document 2), but water-liquefied water has a rapid hardening property because the hydration of the quick-hardening component proceeds. Tends to decrease. When used together with thickeners that are known to be effective in preventing dust generation, many thickeners can only fully function in an aqueous slurry environment, and thickeners completely prevent dust generation. Requires a large amount of thickener to be dropped, so the slurry viscosity is considerably high and clogging is likely to occur during pumping and spraying, and resistance during mixing is increased, resulting in only non-uniform spraying materials. There was a fear.
JP 2000-219555 A JP 2000-302503 A

  It is an object of the present invention to provide a cement-based spraying material and a spraying material construction method that can suppress dust generation and rebound, and can quickly form a strong wall surface that does not collapse after spraying. Let it be an issue.

  In order to solve the problem, the present inventors use calcium aluminate having a strong rapid hardening action on the rapid setting component, slurry the rapid setting component, and are inert to calcium aluminate as a slurrying medium. When divalent lower alcohol is used and inorganic fine powder is added to it, separation and sedimentation hardly occur for a relatively long time, and since it is liquid, there is no dust generation and a rebound suppression effect is created, and the desired spraying properties are maintained. While obtaining the knowledge that a strong wall surface can be formed quickly and easily, the present invention has been completed.

That is, this invention is the construction method of the spraying material represented by the following (1)-(3) and the spraying material represented by (4)-(5). (1) Slurry containing calcium aluminate, divalent lower alcohol, inorganic powder having a BET specific surface area of 10 m ² / g or more which is inert to divalent lower alcohol, and slurry containing cement and water Spray material consisting of (2) The spray material according to (1), wherein the divalent lower alcohol is ethylene glycol. (3) The spray material according to (1) or (2), further comprising a dispersant. (4) Mixing a slurry containing calcium aluminate, divalent lower alcohol and inorganic powder having a BET specific surface area of 10 m ² / g or more, which is inert to the divalent lower alcohol, with a slurry containing cement and water. And the construction method of the spraying material characterized by spraying this mixture. (5) The method for applying a spraying material according to (4) above, further comprising adding a dispersant to the slurry containing at least cement and water.

  According to the present invention, it is possible to easily obtain a spray material in which generation of rebound and dust is remarkably reduced, and this spray material can quickly form a strong wall surface without dripping or peeling after spraying. Can do. In addition, since the spray material according to the present invention uses a method of mixing two kinds of slurry, each slurry can be kneaded for a relatively long time after adjustment, so that restrictions on construction work can be greatly reduced. .

The spray material of the present invention comprises a slurry mainly composed of a rapid hardening component (hereinafter referred to as slurry A) and a slurry mainly composed of cement (hereinafter referred to as slurry B). Calcium aluminate used as a rapid hardening component in slurry A is a general term for a compound containing CaO and Al ₂ O ₃ as main chemical components, a solid solution, a glassy material, or a mixture of these, and is hydrated. If it has activity, it will not be limited. For example, 12CaO · 7Al ₂ O ₃ , CaO · Al ₂ O ₃ , 3CaO · Al ₂ O ₃ , 11CaO · 7Al ₂ O ₃ · CaF ₂ , 4CaO · 3Al ₂ O ₃ · SO _3, etc. The composition which uses these chemical components as an active ingredient may be sufficient. The particle size of calcium aluminate is not limited, but is preferably BET specific surface area of 0.8 to ⁵ m ² / g, more preferably 1.0 to 3.0 m ² / g. BET specific surface area of 0.8 m ² / is less than g reaction activity is low, the desired hardly quick-setting property can be obtained and 5.0 m ² / g greater than the decrease in dispersibility, the cost increase and manufacturing slurry pumping resistance May cause a surge in the price.

  The liquid used for slurrying in Slurry A is a divalent lower alcohol because it has a remarkably low activity with calcium aluminate, dispersibility of calcium aluminate is good, and a stable state is obtained. Any alcohol can be used as long as it is a divalent lower alcohol, but ethylene glycol is preferably used because it has an extremely rapid setting property and strength development property. By using divalent lower alcohol as the slurry liquid and using it together with inorganic powder with a specific surface area as described later, the phenomenon that the sediment settles and solidifies easily occurs when stored for a long period of time is sufficient. There is an inhibitory effect.

For the slurry A, an inorganic fine powder having a BET specific surface area of 10 m ² / g or more which is inert to a divalent lower alcohol is also used. The inorganic fine powder not only has the effect of suppressing rebound of the spray material, but also can suppress the solid-liquid separation of the slurry, so that the slurry A can be kneaded and manufactured. The inorganic fine powder to be used is not limited as long as it is a fine powder that is inert to the divalent lower alcohol and has a BET specific surface area of 10 m ² / g or more and is different from the calcium aluminate used in the slurry. Examples of usable inorganic fine powders include pozzolanic reactive substances such as silica fume, fumed silica, silica, non-hydrated silicate minerals, alumina, limestone, and other ultrafine powders. Also good. More preferably, silica fume or fumed silica having a BET specific surface area of 10 m ² / g or more may be used. An inorganic powder having a BET specific surface area of less than 10 m ² / g is not preferable because it is difficult to obtain a rebound suppressing action. The upper limit of the BET specific surface area of the inorganic fine powder is not particularly limited, but is desirably about 500 m ² / g in order to ensure good dispersibility and avoid an increase in production cost.

  The content of each component in the slurry A is preferably 1 to 100 parts by weight of inorganic fine powder with respect to 100 parts by weight of calcium aluminate. If it is less than 1 part by weight of the inorganic fine powder, it is difficult to obtain a rebound suppressing effect, and if it exceeds 100 parts by weight, the content ratio of calcium aluminate is relatively lowered, so that a large amount of slurry A is required. Adhesion and durability may be reduced. Moreover, what is necessary is just to select suitably content of a bivalent lower alcohol in the range used as a slurry state. When a suitable example is shown, it is 20-200 weight part with respect to 100 weight part of calcium aluminates. If it is less than 20 parts by weight, it becomes difficult to make a slurry, and the viscosity may become so high as to hinder mixing and powder dispersion. If it exceeds 200 parts by weight, the fast-hardening component in the slurry is too dilute, making it practical. Lack. The slurry A is preferably free of water in order to prevent the calcium aluminate from deteriorating and maintain rapid hardness. Even when it is unavoidably contained, it is 1% by weight or less.

  Slurry A can contain components other than those described above as long as the effects of the present invention are not lost, and examples thereof include alkali or alkaline earth metal carbonates and dispersants. It is desirable not to contain water in order to prevent the deterioration of the resin and to maintain the rapid hardness. Further, when it is desired to secure the kneading time, it is desirable that the material does not contain hydraulic or latent hydraulic substances. In the case of containing a dispersant, the chemical component is not limited, but it is preferable to use a dispersant having a dispersing action in an organic solvent. When using a dispersing agent, it is preferable to mix | blend 0.1-3.0 weight part with respect to 100 weight part of calcium aluminates.

  The slurry B used in the present invention is an aqueous slurry formed from at least cement and water. The cement is not particularly limited as long as it is hydraulic. For example, various portland cements such as normal, early strength, very early strength, moderate heat, low heat, blast furnace cement, silica cement, fly ash cement, high belite cement. And other mixed cements, special cements such as alumina cement and eco-cement. Preferably, a cement other than cement mainly composed of calcium aluminate such as alumina cement is used.

  The slurry B can contain components other than cement and water as long as the effects of the present invention are not lost, for example, water reducing agents, high performance water reducing agents, AE water reducing agents, dispersing agents such as high performance AE water reducing agents, natural And artificial fine aggregates, fibers, thickeners, latent hydraulic substances such as fine slag powder, setting retarders, expansion agents, shrinkage reducing agents, water-stopping materials, material separation inhibitors, reflective or luminescent particles, pigments, etc. Can be mentioned. Preferably, those containing dispersants such as water reducing agents and high performance water reducing agents are good. More preferably, those containing fibers and dispersants made of metal, carbon, polymer compounds, and the like are preferable. When the dispersant is included, a dispersing action can be obtained, and since the water ratio can be reduced, dripping from the wall surface and ceiling surface after spraying can be suppressed without impairing quick setting. In particular, it is more preferable that the slurry B contains a dispersant because the sprayability of the present invention composed of the slurry A and B is easily increased and a uniform spray can be obtained. In the present invention, a dispersant may be blended and used in both the slurry A and B. Moreover, the adhesiveness at the time of spraying can be improved by using a fiber, without using many thickening components. In the case where the slurry B is kneaded after preparation, the use of a dispersant is sufficient if the kneading is a short time, but for example, in the case of a relatively long time of 1 hour or more, for example, oxycarboxylate or alkali It is appropriate to add a setting retarder that can be used for mortars such as metal carbonates and concrete.

  The amount of cement and water used in the slurry B is preferably 30 to 60 parts by weight of water per 100 parts by weight of cement. If the amount of water is less than 30 parts by weight, a fluid slurry suitable for spraying may not be obtained. On the other hand, if the amount of water exceeds 60 parts by weight, the rapid setting may not be reduced and the strength development may not be enhanced. In addition, when using dispersants in combination, 0.2 to 2.0 parts by weight with respect to 100 parts by weight of cement, and when using aggregate, 90 to 600 parts by weight with respect to 100 parts by weight of cement are blended. Is recommended.

  What is necessary is just to mix the said slurry A and B for the spraying material of this invention. The mixing method is not limited, and any mixing method can be used. The mixing amount of the slurry A and B is preferably A / B = 0.01 to 0.15 in weight ratio. If the A / B weight ratio is less than 0.01, the quick setting property is insufficient, which is not preferable. If the A / B weight ratio exceeds 0.15, the hydration heat generation becomes high, which causes the occurrence of temperature cracks. This is not preferable.

Further, the spraying material construction method of the present invention comprises mixing at least calcium aluminate, divalent lower alcohol and divalent lower alcohol with an inert inorganic powder having a BET specific surface area of 10 m ² / g or more. Components other than these are also added and mixed to prepare a non-aqueous slurry. The slurry A is applied to such a slurry, and the details of each component used for mixing and the amount of use thereof are the same as those of the slurry A. Separately from this slurry, at least cement and water are mixed, and preferably a dispersant and, if necessary, other components are added and mixed to prepare an aqueous slurry. The slurry B is applied to such a slurry, and the details and the amount of each component used for mixing are the same as those of the slurry B. Next, both slurries are mixed. In the mixing method, each slurry may be transported from a slurry storage section such as a tank separated for each slurry using a pump, a pressure-feeding air medium, or the like, and both slurries may be merged in the middle of transportation or at the ejection section of the spraying device. The slurry merging method is not limited to a known method using, for example, a T-shaped tube or a double tube when merging during transportation. Moreover, when performing confluence | merging in the ejection part of a spraying apparatus, you may make it merge immediately before ejecting within the nozzle of a spraying apparatus, or you may eject each slurry from a separate nozzle, respectively, and you may make it join in the air immediately after ejecting. The structure of the spraying device may be selected as appropriate according to the slurry merging format and construction environment to be employed, and is not particularly limited. The mixing ratio of the two slurries for forming the spray material is set to a value similar to the weight ratio of the slurry A and B, that is, A / B = 0.01 to 0.15.

Hereinafter, the present invention will be described in detail by way of examples.
[Preparation of Slurry A] A calcium aluminate material selected from S1 to S3, a liquid selected from D1 to D5, a material selected from E1 to E6, and a material selected from F1 to F2, Mix for about 5 minutes with a mortar kneading hand mixer so as to achieve the blending amount described in 1. Slurry A (A-1 to A-8 related to the present invention, A-9 to A- for comparison with the present invention) 15) was prepared every 2 liters.
S1: Calcium aluminate I (powder obtained by mixing CaO and Al ₂ O ₃ in a molar ratio of 12: 7 in an electric furnace at about 1600 ° C. and then gradually cooling the powder in a furnace. 7Al ₂ O ₃ crystals substantially consist of 100% Blaine specific surface area of about 4000 g / cm ² )
S2: Calcium aluminate II (a trial product obtained by heating a powder powder in which CaO and Al ₂ O ₃ are mixed at a molar ratio of 2.2: 1 in an electric furnace at about 1600 ° C. and then dry quenching. Vitrification rate 100 %, Blaine specific surface area of about 4000 g / cm ² )
S3: Alumina cement (manufactured by Taiheiyo Material Co., Ltd.)
D1: Monoethylene glycol (commercially available reagent)
D2: Propylene glycol (commercially available reagent)
D3; ethyl alcohol (commercially available reagent)
D4: Butyl alcohol (commercially available reagent)
D5; water (water supply)
E1; Silica fume (BET specific surface area 15m ² / g, made in China)
E2: Fumed silica (BET specific surface area 200 m ² / g, manufactured by Nippon Aerosil Co., Ltd.)
E3: Silica powder (BET specific surface area 3 m ² / g)
E4: Silica powder (BET specific surface area 0.9 m ² / g)
E5: Aluminum oxide powder (BET specific surface area 13 m ² / g, commercially available reagent)
E6: Limestone powder (BET specific surface area 0.9 m ² / g)
F1: anhydrous gypsum (commercially available reagent, BET specific surface area 1.8 m ² / g)
F2: Lithium carbonate (commercially available reagent, BET specific surface area 0.5 m ² / g)

[Preparation of Slurry B] The mortar so that the cement selected from C1 to C3 and the admixture (material) for mortar and concrete selected from M1 to M5 and water are mixed in the amounts shown in Table 2 below. The mixture was mixed for about 5 minutes with a kneading hand mixer to prepare 150 liters of slurry B (B-1 to B-7).
C1: Ordinary Portland cement (manufactured by Taiheiyo Cement Co., Ltd.)
C2: Early strong Portland cement (manufactured by Taiheiyo Cement Co., Ltd.)
C3: Blast furnace cement type B (manufactured by Taiheiyo Cement Corporation)
M1; fine aggregate (crushed sand from Kamiiso, Hokkaido, FM = 2.8)
M2: Vinylon fiber (manufactured by Kuraray Co., Ltd.)
M3: Lithium carbonate (commercially available reagent)
M4: Naphthalenesulfonic acid-based high-performance water reducing agent (trade name “Mighty 100”, manufactured by Kao Corporation)
M5; methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd.)

  [Confirmation of Slurry State Change] Slurries A and B were transferred to separate slurry tanks immediately after their preparation. Each slurry was allowed to stand in the slurry tank for about 1 hour immediately after preparation, and the state change of the slurry was examined. If the material separation such as sedimentation of the slurry components and slurry solidification can be clearly confirmed by visual observation, the kneading property is “X”, and if the clear state change is not seen, the kneading property is “○”. The results are shown in Table 1 for slurry A and Table 2 for slurry B.

  [Spraying method of spray material] Separately from the confirmation of the change in the state of the slurry, each slurry transferred to the slurry tank immediately after production was pumped from each tank to the spraying device through the transport pipe with a squeeze pump without kneading. . The slurry pumping flow rate is 1.0 liters / minute for slurry A and 22.0 liters / minute for slurry B, and the transport pipe just before the spraying device has a Y-shaped tube structure, where both slurries join at that flow rate. Mixed. The mixed slurry was ejected at a constant speed from the nozzle of the spraying device with compressed air using a compressor so that the ejection amount was 23.0 liters / minute, and was installed vertically on a non-gradient ground approximately 2 m ahead of the nozzle tip. It sprayed on the wall surface made from concrell with the spray angle of 90 degree | times. In addition, a vinyl sheet was spread over a wide area on the ground from the nozzle tip to the wall surface.

  [Results of spraying of spray material, etc.] 100 kg of the mixed slurry was sprayed by the spraying method. About 1 minute after the end of spraying, the spray on the wall surface was strongly pressed with a finger for 5 seconds or more. A sprayed product that has been subjected to acupressure within the range that can be visually confirmed does not cause any slight deformation, cracking or peeling, and the sprayed product does not drip. It was judged that there was no sexuality. In addition, the presence or absence of dust generation was judged visually during spraying, and dust generation was determined to be “present” when floating dust was clearly confirmed, and “other” was determined otherwise. Further, the sprayed material dropped from the wall surface was removed, and the sprayed material that bounced off the wall surface during the spraying and dropped was collected from the sheet. The weight of the collected material was measured to obtain X (Kg), and the value of X / 100 was calculated as the rebound rate. These results are shown together in Table 3.

  From Table 3, it can be seen that the spray materials of the present invention (the products of the present invention 1 to 10) all exhibit good quick setting properties, no clear dust generation is observed, and the rebound rate is significantly reduced. . In addition, with respect to the reference product 4 which was prepared for comparison, the slurry A (A-12) started to condense immediately after the preparation, and most of the product solidified during the pumping and could hardly be mixed and mixed with the slurry B. Spray construction was not possible.

Claims (5)

It consists of a slurry containing calcium aluminate, divalent lower alcohol, inorganic fine powder having a BET specific surface area of 10 m ² / g or more which is inert to divalent lower alcohol, and a slurry containing cement and water. Spray material. The spray material according to claim 1, wherein the divalent lower alcohol in the slurry is ethylene glycol. Furthermore, the spraying material of Claim 1 or 2 formed by containing a dispersing agent. A slurry containing calcium aluminate, divalent lower alcohol and inorganic fine powder having a BET specific surface area of 10 m ² / g or more which is inert to the divalent lower alcohol is mixed with the slurry containing cement and water, A spraying material construction method characterized by spraying this mixture. The method for applying a spraying material according to claim 4, further comprising adding a dispersant to the slurry containing at least cement and water.