JP2012036028A - Spraying material and spraying method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spraying material which suppresses generation of dust and improves work efficiency.SOLUTION: The spraying material is prepared by mixing cement concrete containing an alkali metal sulfate and a retarder with a liquid quick-setting agent containing an aluminum source and a sulfur source. The alkali metal sulfate is preferably sodium sulfate, the retarder is preferably sodium gluconate, and a water reducing agent may further be contained in the spraying material. A spraying method is also provided which comprises mixing cement concrete containing an alkali metal sulfate and a retarder with a liquid quick-setting agent containing an aluminum source and a sulfur source. It is preferable that the cement concrete and the liquid quick-setting agent are conveyed by air and sprayed.

Description

The present invention relates to, for example, a spraying material sprayed onto a ground surface exposed in a tunnel or a slope such as a road, a railway, and a waterway, and a spraying method using the same.

In order to prevent collapse of exposed ground such as tunnel excavation, a spraying method of quick setting concrete in which a quick setting agent is mixed with concrete is performed (Patent Document 1). This method usually involves preparing sprayed concrete at a cement, aggregate, and water metering and mixing plant installed at the excavation site, transporting it with an agitator car, pumping it with a concrete pump, and using a confluence pipe installed in the middle. This is a method of mixing with a rapid setting agent fed from the other side and spraying it to the ground surface as a quick setting sprayed concrete until a predetermined thickness is reached.

Accelerating agents include calcium aluminate, a mixture of alkali metal aluminate and alkali carbonate, etc., a mixture of calcium aluminate, alkali metal aluminate, and alkali carbonate, calcium aluminate and 3CaO, etc. A mixture with SiO ₂ is known (Patent Documents 2 to 5).

These quick setting agents have a function of promoting the setting of cement, and all of them are mixed with cement concrete and sprayed on the ground surface. In the method of adding the quick setting agent, there is a possibility that the amount of dust is usually increased due to powder mixing by pneumatic transportation. For this reason, the work environment may be deteriorated, and it is necessary to wear protective glasses, a dust mask, or the like when spraying. Therefore, a construction method with a smaller amount of dust has been demanded.

As a method of generating less dust, a method is proposed in which a quick setting agent is slurried and added to cement concrete, and then an alkali metal aluminate solution is separately pumped, mixed, and sprayed. (Patent Document 6). Since this method uses a highly alkaline liquid, it is difficult to handle, and when spraying, protective glasses or gloves are required, and there is a problem that workability is reduced.

As a construction method with a small amount of dust generation, there is proposed a quick setting method for improving a working environment by slurrying a quick setting agent and blending alum into cement concrete (Patent Document 7). In recent years, a quick setting method with improved quick setting has been proposed in terms of further improving workability and dust reduction effect and shortening the construction period (Patent Document 8).

From the viewpoint of health and safety, a quick setting agent having a lower pH value than a quick setting agent in which alkali metal aluminate or alkali metal carbonate is mixed with calcium aluminate, for example, a neutral or slightly acidic quick setting agent. It has been demanded. As a liquid accelerating agent satisfying this requirement, those containing a basic aluminum salt or organic carboxylic acid as a main component (Patent Document 9), those containing aluminum sulfate or alkanolamine as a main component (Patent Documents 10 to 12), aluminum A basic aqueous solution, lithium silicate, and lithium aluminate as main components (Patent Document 13) have been proposed.

These liquid quick-setting agents are difficult to obtain initial strength, and there is a risk of peeling off when blown thickly in tunnel tunnels compared with conventional quick setting agents based on calcium aluminate. It is necessary to increase the component concentration in the liquid quick-setting agent to improve the performance of the liquid quick-setting agent. However, these liquid accelerating agents have a limit in solubility. When the temperature at the time of storage of the liquid accelerating agent is lowered, the solubility is lowered and precipitates or the like may be seen.

Therefore, one or more selected from the group of inorganic liquid compounds consisting of an acidic liquid accelerator mainly composed of aluminum or sulfur and powdered aluminum sulfate, sulfate, aluminate, or hydroxide are added. A spraying material characterized by this has been proposed (Patent Document 14).

However, powdered inorganic compounds have strong reactivity with cement and cannot be added to cement concrete in advance, so a powder transport device to be added to cement concrete just before spraying is necessary, and the construction may be complicated. The powder conveying device is a device for adding a powdered inorganic compound to cement concrete by compressed air.

Japanese Patent Publication No. 60-4149 Japanese Patent Laid-Open No. 64-051351 Japanese Examined Patent Publication No. 56-27457 JP-A-61-026538 JP 63-2105050 A Japanese Patent Laid-Open No. 5-139804 JP-A-5-097491 JP 2003-81664 A JP-T-2001-509124 Japanese Patent Laid-Open No. 10-087358 JP 2002-047048 A JP 2003-246659 A JP 2001-130935 A JP 2007-55831 A

The present invention is advantageous in terms of quantitativeness and workability, and when adjusting cement concrete, a powdery inorganic compound can be added to cement concrete in advance, and is equivalent to a quick setting agent mainly composed of calcium aluminate. A spray material having properties is provided.

That is, the present invention is a spray material obtained by mixing cement concrete containing an alkali metal sulfate and a retarder and a liquid quick-setting agent containing an aluminum source and a sulfur source. The spraying material that is sodium sulfate, the spraying material in which the retarder is sodium gluconate, the spraying material comprising a water reducing agent, and containing an alkali metal sulfate and a retarder This is a spraying method in which cement concrete is mixed with a liquid accelerator containing an aluminum source and a sulfur source, and the retarder is sodium gluconate. The water reducing agent is added to cement concrete. A spraying method comprising the above, wherein the cement concrete is air-conveyed and sprayed, and the liquid quick setting agent is air-conveyed and sprayed. It is kicking 該吹 with method.

By adopting the spraying material of the present invention and the spraying method using the same, it is possible to suppress the generation of dust generated in the spraying work such as a tunnel and to improve workability. The present invention has an effect that high quick setting can be obtained even under conditions in which spring water or natural ground surface deteriorates.

Unless otherwise specified, parts and% in the present invention are shown on a mass basis. The cement concrete in the present invention refers to cement paste, mortar, and concrete.

Examples of the alkali metal sulfate used in the present invention include sulfates (alkali metals such as sodium, potassium and lithium).

Examples of the alkali metal sulfate include sodium sulfate, potassium sulfate, and lithium sulfate.

Among the alkali metal sulfates used in the present invention, sodium sulfate is preferable in that the addition rate is small, slump and strength development are large, rebound and dust are small, and there is no influence of salt damage on concrete.

When the alkali metal sulfate used in the present invention is mixed with a liquid accelerating agent, it has an effect of improving the setting property and strength development. The alkali metal sulfate is used for the purpose of improving the adhesion property and strength development of cement concrete. Alkali metal sulfates include anhydrous salts and hydrated salts, both of which can be used.

The amount of alkali metal sulfate used is preferably 80 to 99 parts, more preferably 85 to 95 parts, in 100 parts of the admixture. If the amount is less than 80 parts, the setting properties may not be improved even if mixed with a liquid quick-setting agent, and rebound and dust may increase. If the amount exceeds 99 parts, the workability of cement concrete may be deteriorated.

The retarder used in the present invention is used to reduce the hydration rate of cement and retard setting and hardening.
Cement concrete pre-blended with alkali metal sulfate is less likely to promote hydration than cement concrete not pre-blended, and improves the fresh properties of cement concrete, such as fluidity.

Examples of the retarder used in the present invention include monocarboxylic acids, dicarboxylic acids, polycarboxylic acids, oxycarboxylic acids, organic acids such as amino acids, and salts thereof (sodium, potassium, lithium, calcium, magnesium, etc.). .

As retarders, formic acid, acetic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, phthalic acid, terephthalic acid, heptonic acid, gluconic acid, glycolic acid, malic acid, tartaric acid Citric acid, salicylic acid, mandelic acid, ethylenediaminetetraacetate, glutamic acid, aspartic acid, and salts thereof.

Among the retarders used in the present invention, the addition rate is low, and the concrete fresh properties due to accelerated hydration of alkali metal sulfate are not deteriorated, and good strength development is achieved when a liquid quick-setting agent is added. In terms of the obtained point, one or more of gluconic acid, malic acid, tartaric acid, citric acid and salts thereof are preferable, and sodium gluconate is more preferable.

The amount of retarder used is preferably 1 to 20 parts, more preferably 5 to 15 parts, in 100 parts of the admixture. If it is less than 1 part, the fresh properties of the cement concrete may be deteriorated, and if it exceeds 20 parts, the quick setting property may be reduced and the rebound rate may be increased.

The admixture used in the present invention contains an alkali metal sulfate and a retarder. The amount of the admixture used is preferably 1 to 10 parts and more preferably 3 to 7 parts with respect to 100 parts of cement of cement concrete. When the amount is less than 1 part, the physical properties may not be changed from the case where the liquid quick-setting agent is used as a simple substance. When the amount exceeds 10 parts, the rapid setting property may be deteriorated and rebound and dust may increase.

The admixture used in the present invention is preferably mixed with cement concrete in advance in a batcher plant.

There are no particular limitations on the feedstock for the aluminum source of the liquid accelerator used in the present invention. Examples of the aluminum source feedstock include amorphous or crystalline aluminum hydroxide, aluminum sulfate, aluminate and other inorganic aluminum compounds, organic aluminum compounds, and compounds such as aluminum complexes. One kind or two or more kinds can be used. In these, the aluminum sulfate used also as a feedstock of a sulfur source is preferable.

The amount of the aluminum source of the liquid quick setting agent is preferably 6 to 15 parts, more preferably 8 to 12 parts in terms of solid Al ₂ O _{3 in} 100 parts of the liquid quick setting agent in terms of quick setting. .

The feedstock for the sulfur source used in the present invention is not particularly limited. Sulfur source feedstocks include elemental sulfur such as sulfur and sulfur white, sulfides, sulfuric acid or sulfates, sulfites or sulfites, thiosulfuric acid or thiosulfates, and organic sulfur compounds. 1 type or 2 types or more can be used. Among these, sulfuric acid or sulfate is preferable, sulfate is more preferable, and aluminum sulfate is most preferable because of its high solubility in water, low manufacturing cost, and excellent quick setting properties.

The amount of the sulfur source used for the liquid quick setting agent is preferably 10 to 25 parts, more preferably 15 to 20 parts in terms of solid SO _{3 in} 100 parts of the liquid quick setting agent, in terms of quick setting.
The liquid accelerator used in the present invention is an acidic liquid accelerator. The pH of the liquid accelerator is preferably 6 or less. If the pH is high, the stability of the liquid accelerator may be impaired.

The amount of the liquid quick setting agent used in the present invention is preferably 4 to 12 parts, more preferably 6 to 10 parts, relative to 100 parts of cement. If the amount is less than 4 parts, the excellent quick setting property may not be exhibited. If the amount exceeds 12 parts, the long-term strength development property may be deteriorated.

The liquid quick setting agent used in the present invention can improve the quick setting property by heating at a temperature in the range of 20 to 90 ° C. and mixing it with cement concrete.

The solid content concentration of the liquid accelerator used in the present invention is preferably 20 to 35%, and more preferably 25 to 35%.
If it is less than 20%, there is a possibility that an excellent quick setting property may not be obtained. If it exceeds 35%, solid content is precipitated depending on the temperature condition, the viscosity of the liquid is increased, and the pumpability is lowered. There is a risk of failure of the pump itself.

The cement concrete used in the present invention may use a water reducing agent. As the water reducing agent, a high performance water reducing agent is preferable. High performance water reducing agents such as alkylallyl sulfonic acid type, naphthalene sulfonic acid type, melamine sulfonic acid type, lignin sulfonic acid type, polycarboxylic acid type and polyethylene glycol type (including high performance AE water reducing agent) ).

Among the high performance water reducing agents, polycarboxylic acid type and / or polyethylene glycol type are preferable, and polyethylene glycol type is more preferable.

0.1-5 parts is preferable with respect to 100 parts of cement, and 0.5-2 parts is more preferable.

The cement used in the present invention is not particularly limited. As the cement, various types of normal, early strong, super early strong, moderately hot and low heat Portland cement, filler cement in which blast furnace slag, fly ash and fine limestone powder are mixed with Portland cement, municipal waste incineration ash and sewage are used. Examples include environmentally friendly cement (eco-cement) manufactured using sludge incineration ash as a raw material, and these can be used in the form of fine powder. The ratio of the mixture and cement in the mixed cement is not particularly limited, and a mixture obtained by mixing these admixtures more than expected by JIS can be used.

The cement concrete used in the present invention contains cement and aggregate. As the aggregate, one having a low water absorption rate and high aggregate strength is preferable. The maximum dimension of the aggregate is not particularly limited as long as it can be sprayed. Examples of fine aggregates include river sand, mountain sand, sea sand, lime sand, and quartz sand. Examples of coarse aggregate include river gravel, mountain gravel, and lime gravel. Examples of the coarse aggregate include crushed sand and crushed stone.

The water-cement ratio (W / C) of the cement concrete used in the present invention is preferably 30 to 75%, more preferably 35 to 70%, and most preferably 40 to 65%. When it is less than 30%, the viscosity of the sprayed cement concrete is large, and the spraying workability is deteriorated. When it exceeds 75%, the strength development property and the setting property may be adversely affected. In addition, the water in a liquid quick-setting agent is not considered for the water of water cement ratio here.

In the spraying method of the present invention, conventional spraying equipment can be used. The spray pressure of cement concrete is preferably 0.1 to 0.8 MPa, and more preferably 0.2 to 0.5 MPa. Spray rate of cement concrete is preferably ^{4~20m 3 / h, 8~12m 3 /} h is more preferable. The pressure of the liquid quick-setting agent is preferably 0.01 to 0.3 MPa higher than the pressure of the cement concrete so that the inside of the pressure-feeding pipe is not blocked when the cement concrete is mixed into the liquid quick-setting agent. More preferably, it is larger by 0.05 to 0.15 MPa.

Examples of the spraying method using the quick setting agent used in the present invention include various spraying methods according to the required physical properties, economy, workability, and the like. As a spraying method using the quick setting agent used in the present invention, any of a dry spraying method and a wet spraying method is possible.

Unless otherwise noted, the examples were tested at 20 ° C. Cement 400 kg / ^{m 3,} fine aggregates 1058kg / ^{m 3,} coarse aggregate 673kg / ^{m 3,} water 200 kg / ^{m 3,} the concrete superplasticizer 4 kg / ^{m 3,} alkali metal sulfate mixed ratio shown in Table 1 5 parts of an admixture composed of a salt (hereinafter referred to as sulfate) and a retarder having a mixing ratio shown in Table 1 was added to 100 parts of cement. After adding the admixture, a concrete slump test was conducted. After completion of the slump test, the concrete was pumped by a concrete pump “MKW-25SMT” (manufactured by Shintech Co., Ltd.) under conditions of a spraying pressure of 0.4 MPa and a spraying speed of 10 m ³ / h. On the other hand, the liquid quick setting agent is pumped using “TA-3DX” manufactured by Aritsu Kogyo Co., Ltd. under the condition of a pumping pressure of 0.5 MPa so as to be 8 parts to the cement. The agent was mixed with shotcrete fed from the other side of the Y-shaped tube to obtain quick setting shotcrete. Concrete compression strength, rebound rate, and amount of dust were measured for this quick setting shot concrete.

<Materials used>
Sulfate A: anhydrous sodium sulfate, manufactured by Kishida Chemical Co., Ltd., reagent grade 1 sulfate B: potassium sulfate, reagent sulfate C: lithium sulfate, reagent, monohydrate retarder a: sodium gluconate, commercially available retarder b: sodium citrate, reagent retarder c: sodium tartrate, reagent cement: ordinary Portland cement, commercially available, brain value 3,200 cm ² / g, specific gravity 3.16
Fine aggregate: Himekawa water system river sand, Itoigawa City, Niigata Prefecture, surface dry state, specific gravity 2.62
Coarse aggregate: Gravel in Himekawa water system, Itoigawa City, Niigata Prefecture, surface dry condition, specific gravity 2.67
Liquid quencher: solid content concentration 28%, pH 2.6, (solid content is Al ₂ O ₃ : 9.5%, SO ₃ : 18.5%), commercial product, high-performance water reducing agent containing aluminum sulfate: Polyethylene glycol, trade name “FTN-30”, manufactured by Grace Chemicals Co., Ltd.

<Measurement method>
Slump test (concrete slump): Measured according to JIS A1101. The age was 3 minutes, 30 minutes, 60 minutes and 90 minutes after the admixture was added. As a comparative example, a concrete slump without admixture was also measured.
Concrete compressive strength (compressive strength): The compressive strength at an age of 1 hour is determined by covering a pin placed on a pullout formwork with a width of 25 cm and a length of 25 cm from the surface of the pullout formwork with quick setting sprayed concrete. The pin was pulled out from the back side, and the pullout strength at that time was determined, and the compressive strength was calculated from the formula of (compressive strength) = (pullout strength) × 4 / (test specimen contact area). The compressive strength after 1 day of age is 20 tons pressure-resistant machine by spraying quick setting sprayed concrete on a form of width 50cm x length 50cm x thickness 20cm, and collecting the specimen 5cm in diameter x 10cm in length. And the compressive strength was determined.
Rebound rate (rebound): Rapid setting shot concrete was sprayed on a simulated tunnel having a height of 3.5 m and a width of 2.5 m created in an arch shape with an iron plate at a pumping speed of 10 m ³ / h for 10 minutes. After that, (Rebound rate) = (Amount of quick setting sprayed concrete dropped without adhering to the simulated tunnel) / (Amount of quick setting shot concrete sprayed to the simulated tunnel) x 100 (%) did.
Dust amount (rebound): Rapid setting spray concrete was sprayed on the simulated tunnel at a pumping speed of 10 m ³ / h for 10 minutes. Thereafter, the amount of dust was measured at a fixed position of 3 m from the spraying place.

From Table 1, it was found that the sodium sulfate alone became a condensed state in 30 minutes after the admixture was added, and spraying was impossible. On the contrary, with the retarder alone, a good slump was maintained even after 90 minutes from the addition of the admixture, but the strength did not develop for 1 hour, and rebound and dust increased. When the amount of the retarder of the admixture exceeds 20 parts, Experiment No. It was shown that the properties equivalent to or higher than those of 1-1 were not exhibited. The effects of concrete slump and strength development are shown in Experiment No. In these experimental examples, in all items of concrete slump, compressive strength, rebound, and dust, Experiment No. It was shown that the property better than 1-1 was exhibited.

When the type of sulfate was changed from sodium salt to potassium salt or lithium salt, potassium salt had a slight decrease in strength for 1 hour, and lithium salt had a slight decrease in concrete slump retention and daily strength. When the type of retarder was changed from sodium gluconate to sodium citrate or sodium tartrate, concrete slump retention was worse than sodium gluconate.

An admixture comprising 90 parts of sulfate A and 10 parts of retarder a was carried out in the same manner as in Example 1 except that the amount shown in Table 2 was added to 100 parts of cement. The results are shown in Table 2.

From Table 2, when the amount of the admixture used is less than 1 part, the compression strength, rebound, and dust are No. It was not different from the case where 1-1 admixture was not blended. By adding 1 part or more of the admixture, the compressive strength at the age of 1 hour and the compressive strength at the age of 1 day were improved, and the rebound and dust decreased, and good results were shown. Therefore, when the amount of the admixture is 1 to 10 parts with respect to 100 parts of cement, a better result was obtained than when only the liquid quick-setting agent was used.

The same procedure as in Example 1 was performed except that an admixture composed of a sulfate having a mixing ratio shown in Table 3 and a retarder a having a mixing ratio shown in Table 3 was added. The results are shown in Table 3.

<Materials used>
Sulfate D: anhydrous aluminum sulfate, commercial product, acid salt, comparative example

From Table 3, as a result of testing by changing the sulfate from sodium sulfate to aluminum sulfate, it was difficult to obtain a concrete slump, and the slump aggregated without holding for 90 minutes, resulting in a deterioration in workability. It was. For this reason, it was difficult to add aluminum sulfate to concrete in advance.

As an example, the liquid quick-setting agent was stored in a 100 ml beaker under the conditions of a temperature of 20 ° C. and a humidity of 60% for 1 week, and precipitates were confirmed from the appearance.
Thereafter, in 700 g of cement, 2100 g of fine aggregate, 350 g of water, 5 parts of an admixture (the admixture is composed of 90 parts of sulfate A and 10 parts of retarder a), and 100 parts of cement. On the other hand, 8 parts of a liquid setting agent was added, and a Proctor test and a compressive strength test were performed.
As a comparative example, in a 100 ml beaker, the amount of sulfate A shown in Table 4 with respect to 100 parts of cement was dissolved in a liquid quick-set agent while heating and stirring to 90 ° C. to prepare a liquid quick-set agent mixture. did. The liquid quick-setting agent mixture was stored for 1 week under conditions of a temperature of 20 ° C. and a humidity of 60%, and precipitates were confirmed from the appearance.
Thereafter, 8 parts of the liquid quick-setting agent mixture was added to 100 parts of cement in a mortar composed of 700 g of cement, 2100 g of fine aggregate, and 350 g of water, and the physical properties of the Proctor test and compressive strength test were measured.
The results are shown in Table 4.

<Test method>
Method for confirming deposit (precipitate): The amount of sediment accumulated in the beaker was confirmed by the scale of the beaker.
Proctor test (Proctor): In accordance with JSCE D102, after adjusting the mortar, add the liquid quick-setting agent, measure the Procter penetration resistance value when adding the liquid quick-setting agent to the mortar, and determine the start time and end time It was measured.
Compressive strength test: Similar to the Proctor test, the compressive strength was measured in accordance with JSCE D102 when a liquid quick-setting agent was added to the mortar.

From Table 4, by mixing sodium sulfate in cement concrete in advance, the components in the liquid-to-quick setting agent do not precipitate, and quick setting and strength development are obtained.

Since sodium sulfate has a limited solubility, when 3 parts of it was added to the cement, gel-like precipitates accumulated up to 10 ml on the bottom scale of the beaker. As the amount of sodium sulfate was increased, the amount of the precipitates increased, and by adding 10 parts or more of sodium sulfate to the liquid quick-setting agent in advance, the liquid was completely gelled. The gelled material was mixed and put into a mortar, but it was not blended well into the mortar, resulting in a failure to improve the proctor and compressive strength.

It is preferable to add the sulfate to cement concrete in advance.

When the spray material of the present invention is used, the physical properties of the current liquid setting agent can be improved, and it is not necessary to add an admixture immediately before spraying, so that workability and safety are improved.

Claims (9)

A spray material obtained by mixing cement concrete containing an alkali metal sulfate and a retarder and a liquid quick-setting agent containing an aluminum source and a sulfur source. The spraying material according to claim 1, wherein the alkali metal sulfate is sodium sulfate. The spraying material according to claim 1 or 2, wherein the retarder is sodium gluconate. The spray material according to claim 1, comprising a water reducing agent. A spraying method comprising mixing cement concrete containing an alkali metal sulfate and a retarder and a liquid quick-setting agent containing an aluminum source and a sulfur source. The spraying method according to claim 5, wherein the retarder is sodium gluconate. The spraying method according to claim 5 or 6, wherein the water reducing agent is contained in cement concrete. The spraying method according to claim 5, wherein the cement concrete is air conveyed and sprayed. The spraying method according to claim 5, wherein the liquid quick setting agent is air-conveyed and sprayed.