JP5010209B2 - Spraying material and spraying method using the same - Google Patents

Description

  The present invention mainly relates to a spraying material for repairing / reinforcing concrete structures in the field of civil engineering and construction, and a spraying method using the same.

When the concrete structure deteriorates due to salt damage, neutralization, freezing and thawing, chemical corrosion, or the like, the surface is cracked or floated. In addition, even when subjected to fatigue or fire damage due to repeated loading, concrete pieces are peeled off due to cracks or explosions. As countermeasures, a construction is performed in which a deteriorated portion is confirmed by a hammering inspection or the like, removed by an electric pick, an air pick, a water jet, or the like, and newly repaired with a repair member.
In such repair work, spraying methods are often applied when the repair cross-sectional area is wide. The construction method by spraying is generally a method in which mortar that has been kneaded is pumped with a pump, mixed with compressed air, and blown off the mortar. The system is mechanized, so the construction speed is fast and repairs are performed. There is an advantage that it is excellent in adhesion to the cross section and can be densely filled on the back side of the reinforcing bar.

In the spraying method, a polymer cement mortar containing a polymer emulsion specified in JIS A 6203 is often used as the mortar.
Mixing polymer emulsions can improve durability, improve adhesion, and reduce dust and rebound, but polymer emulsions are expensive materials and expensive as spray mortar. is there. Moreover, the spraying thickness per layer of the spray material mixed with the polymer emulsion is less than 50 mm when sprayed on the ceiling surface, and if the thickness is further increased, sagging or peeling may occur.
On the other hand, in order to increase the spraying thickness, there is a spraying method in which a quick setting agent for promoting hardening of the cement is added to the polymer cement mortar, and a thickness of 50 mm or more is possible. In order to ensure stable thickening properties, it is essential to add a quick setting agent, and it is difficult to ensure stable thickening properties without using a quick setting agent.
Also known is the technology of mixing quick setting agent into cement mortar that does not contain polymer emulsion, and it is possible to thicken more than 50mm, but primary lining of tunnels, prevention of collapse of ground, protection of slope, etc. The use is limited. In fact, the long-term durability performance of repair materials is not required.

There is also known a technique that can reduce dripping and rebound as a spraying material even without using a polymer emulsion, by blending a holmite-based mineral or a montmorillonite-based mineral without using a quick setting agent.
For example, crushed material of holmite mineral is 0 by weight ratio of cement to cement with respect to mortar in which cement: sand: fly ash or fine slag powder is 1: 2.7: 0.1 to 4.0: 1.0. A spraying material containing 0.5 to 5.0%, and further containing a water reducing agent at a weight ratio of 0.5 to 5.0% (see Patent Document 1).
Moreover, the spraying material containing 100-400 weight part of fine aggregates and 0.01-10 weight part of montmorillonite minerals with respect to 100 weight part of hydraulic cements (refer patent document 2).
Furthermore, in the case of the conventional construction method, the coating thickness per time is about 20 to 40 mm on the wall surface and about 10 to 20 mm on the ceiling surface, and it is necessary to apply a multilayer coating. Reference 3).
Japanese Patent Laid-Open No. 06-264449 Japanese Patent Laid-Open No. 08-217514 JP 2002-201058 A

On the other hand, many materials used for repair members such as sprayed mortar are difficult to crack, but cracks may occur due to various factors such as environmental conditions, construction methods, and external forces.
In particular, in the case of cracks due to environmental conditions, the moisture dissipation rate increases under the influence of temperature, ventilation, and humidity, and initial cracks that occur before or at the beginning of curing may become a problem. In particular, care should be taken in places where outdoor construction and proper curing cannot be performed. As a method of reducing the initial cracking, there is a method of suppressing water dissipation by water spray curing, sheet curing, etc., but when these curing measures cannot be taken, an emulsion type film curing agent is sprayed or the material itself is initially It is necessary to impart crack resistance, and as a method for imparting initial crack resistance to the material itself, there is a method of mixing short fibers (see Non-Patent Document 1).
Toshihiro Hamada, Toshishi Suemori, Tadashi Saito, Takayuki Hirai, Experimental research on plastic shrinkage cracking of concrete with vinylon short fibers, Concrete Engineering Annual Papers, Vol. 22, no. 2, pp. 319-324, 2000

By mixing the short fibers, it is considered that the effect of dispersing the stress acting when cracks are generated and reducing cracks can be expected. The fiber diameter is 50 μm or less, and mixing as much as possible in the material has a high crack reduction effect. As the types of short fibers, organic fibers such as vinylon fibers, polypropylene fibers, and nylon fibers, and inorganic fibers such as steel fibers, carbon fibers, glass fibers, and rock wool are generally known. Organic fibers is poor when dispersibility of mixing the dry mortar, may not be uniform mixing can fiber balls or the like is added lot, the steel fibers are difficult to make fiber diameter below 50.mu. m, the carbon fiber is very The glass fiber has a problem that the glass fiber is inferior in alkali resistance and acid resistance.
Rock wool is an artificial mineral fiber made of andesite, basalt, slag, etc. as raw materials, melted at a high temperature of 1500-1600 ° C in a cupola or electric furnace, and blown away from the furnace with centrifugal force, compressed air, or high-pressure steam. Although it is a kind and inexpensive, it has a problem that it cannot be uniformly mixed with dry mortar because its form is cottony or granular, and if artificial mineral fibers are mixed with dry hydraulic material, blow it away. What was spun and made into fiber is preferable rather than the thing made into wool. For example, a cement composite material reinforced with fly ash fiber obtained by melt spinning and pulverizing coal ash at a high temperature of several thousand degrees is known (see Patent Documents 4 and 5). Moreover, the manufacturing method which melt-spins basalt at 1500-1600 degreeC and makes it into a fiber is known (refer patent document 6).
Japanese Patent Laid-Open No. 06-340461 Japanese Patent Laid-Open No. 06-340462 Japanese Translation of National Publication No. 09-500080

Conventionally, the above-mentioned polymer cement mortar usually used as a repair mortar for spraying method has a spraying thickness of 40 mm or less. If the repair depth is deep, the sprayed mortar becomes somewhat hard. It was necessary to repair the cross section by spraying it several times. In particular, in order to ensure a spraying thickness of 90 mm or more, it was necessary to use a quick setting agent together.
Further, the polymer emulsion is an expensive material, and there is a problem that the cost of the repair mortar itself is increased. Moreover, when not using polymer emulsion and using a quick setting agent together, there existed a subject that durability performance was inferior compared with general concrete.
In addition, when not using a quick-setting agent, blending with holmite minerals and montmorillonite minerals reduces sagging and rebound and improves the thickening properties, but the durability performance as a repair material and the stability on the ceiling surface are also stable. There was no material with the ability to thicken 90 mm or more.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors can achieve a thickness of 90 mm or more by one spraying without using a quick setting agent by combining specific materials. In addition, the inventors have found that mixing a specific fiber is excellent in uniform mixing properties when mixed with dry mortar, and can impart better initial crack resistance, and the present invention has been completed.

That is, this invention takes the following structures in order to solve the said subject.
(1) Cement, pozzolanic fine powder, polymer thickener and / or holmite mineral, aggregate sand, lightweight aggregate, expansion material, shrinkage reducing agent, fluidizing agent and / or an air entraining agent, a setting accelerator, fiber diameter was melt spinning 2 to 50 [mu] m, fiber length and also contains a basalt fiber convergence state is 2 to 15 mm, with respect to 100 parts by weight of cement, pozzolanic micro 3 to 20 parts by mass of powder, 0.02 to 0.5 parts by mass of polymer thickener, 0.02 to 5 parts by mass of holmite-based mineral, 0.02 to 0.5 parts by mass of fluidizing agent, A spraying material in which the setting accelerator is 0.1 to 1 part by mass, the melt-spun basalt fiber is 0.1 to 10 parts by mass, and the lightweight aggregate is 2 to 15 parts by mass with respect to 100 parts by mass of sand. .
(2) 100 to 260 parts by mass of aggregate sand with respect to 100 parts by mass of cement, and 2 to 15 parts by mass of lightweight aggregate with a bulk density of 0.7 g / cm ³ or less with respect to 100 parts by mass of sand ( Spray material of 1).
(3) The spray material according to (1) or (2), wherein the polymer thickener is hydroxyethyl methylcellulose.
(4) The spray material according to any one of (1) to (3), wherein a holmite mineral having a crystalline silica content of 1% by mass or less is used.
(5) The shrinkage reducing agent is a powdered polyoxyalkylene derivative, the general formula of which is represented by X {O (AO) nR} m, and X is a residue of a compound having 2 to 8 hydroxyl groups, AO is An oxyalkylene group having 2 to 18 carbon atoms, R is a hydrogen atom, a hydrocarbon group having 1 to 18 carbon atoms, or an acyl group having 2 to 18 carbon atoms, n is 30 to 1000, m is 2 to 8, and the oxy The spraying material according to any one of (1) to (4), wherein 60 mol% or more of the alkylene group is an oxyethylene group.
(6) A spraying method in which the spraying thickness per layer is 90 mm or more using the spraying material according to any one of (1) to (5).
(7) Concrete repaired using the spray material of any one of (1) to (5).

  With the spraying material of the present invention and the spraying method using the same, it is possible to thicken by one spraying and to shorten the construction time. Further, by blending a specific fiber, it is excellent in uniform mixing property when mixed with dry mortar, and more excellent initial crack resistance can be imparted.

  Hereinafter, the present invention will be described in detail.

  The cement used in the present invention is not particularly limited, but various portland cements defined in JIS R 5210, various mixed cements defined in JIS R 5211, JIS R 5212, and JIS R 5213, Examples thereof include one or more selected from blast furnace cement, fly ash cement, silica cement, filler cement mixed with limestone powder, alumina cement and the like, which are manufactured at the admixture mixing rate specified in JIS or more.

The pozzolanic fine powder used in the present invention is intended to impart thixotropic properties and improve the compactness of the hardened structure.For example, blast furnace granulated slag, blast furnace slow-cooled slag, converter slag and other slag, silica fume, Examples include fly ash and other natural pozzolanic active substances represented by volcanic ash. Furthermore, considering the improvement effect of chloride ion penetration resistance, it is preferable to use blast furnace granulated slag, blast furnace slow-cooled slag, and a mixture thereof.
The particle size of the pozzolanic fine powder is not particularly limited, but is preferably 3000 cm ² / g or more.

  The amount of the pozzolanic fine powder used is preferably 3 to 20 parts by mass, more preferably 5 to 15 parts by mass with respect to 100 parts by mass of cement. If the amount is less than 3 parts by mass, the thixotropic property is not sufficiently imparted. If the amount exceeds 20 parts by mass, the thixotropic property is too high and it is difficult to ensure fluidity.

The polymer thickener used in the present invention is for adjusting the viscosity of the mortar and is not particularly limited, but is generally called a water-soluble polymer substance. , Polyvinyl alcohol, polyacrylic acid and its sodium and potassium salts, polyethylene oxide, etc., used to prevent the mortar from bouncing off and falling off, and to improve the sliding of the mortar during pumping Is done.
Of these, hydroxyethyl methylcellulose is preferred. Hydroxyethyl methylcellulose has a hydroxyethoxyl group content of 4 to 20%. This powder is mixed with hot water to form a 2% aqueous solution, dispersed, cooled with stirring, and light transmittance at 30 ° C. Is preferably 45% or more. This cellulose derivative is characterized by excellent solubility in alkali in a wide temperature range from low temperature to high temperature, so there is no variation in viscosity imparting effect, and when used in combination with holmite minerals, it is stable and hardly affected by temperature. Thixotropic properties can be obtained. It is also called other water-soluble polymer substances, and methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyacrylic acid or its sodium salt or potassium salt, and polyethylene oxide may be used in combination. Is possible.

  The usage-amount of a polymer thickener is 0.02-0.5 mass part normally with respect to 100 mass parts of cement, and 0.05-0.3 mass part is more preferable. If the amount is less than 0.02 parts by mass, it is not sufficient to reduce the rebound of the mortar. If the amount exceeds 0.5 parts by mass, the improvement of the effect may not be expected.

The holmite mineral used in the present invention is a fibrous inorganic mineral that imparts thixotropic properties. For example, attapulgite or palygorskite of hydrous magnesium aluminum silicate, sepiolite of hydrous magnesium silicate can be mentioned. Among them, the use of attapulgite is preferable because it is difficult to inhibit fluidity.
The average length of the holmite-based mineral is preferably 1 to 3 microns from the viewpoint of giving appropriate thixotropic properties. Further, it is preferable from the viewpoint of safety to use a holmite mineral having a crystalline silica content of 1% or less.

  0.02-5 mass parts is preferable with respect to 100 mass parts of cement, and, as for the usage-amount of a holmite-type mineral, 0.06-3 mass parts is more preferable. If the amount is less than 0.02 parts by mass, the thixotropic property is not sufficient, and if it exceeds 5 parts by mass, the fluidity may be inhibited.

The aggregate sand used in the present invention has a bulk density of more than 0.7 g / m ³ and usually uses natural aggregates produced from rivers, mountains, and the sea, and two or more of these in combination. Mixed aggregates can be used.
The aggregate may be mixed at the construction site, but when it is mixed with cement in advance, a dry aggregate obtained by drying the aggregate may be used.

  As for the usage-amount of aggregate, 50-260 mass parts is preferable with respect to 100 mass parts of cement. If it is less than 50 parts by mass, dripping may increase when sprayed, and if it exceeds 260 parts by mass, rebound may increase.

The lightweight aggregate used in the present invention has a bulk density of 0.7 g / cm ³ or less, and is used for the purpose of reducing the mortar density in order to prevent sagging immediately after spraying.
The type of lightweight aggregate is not particularly limited, but recycled materials such as foam and waste glass fired from natural materials such as fly ash balloons, shirasu balloons and obsidian generated from thermal power plants. The raw material may be fired, and any bulk density of 0.7 g / cm ³ or less can be used.

  2-15 mass parts is preferable with respect to 100 mass parts of sand, and, as for the usage-amount of a lightweight aggregate, 4-10 mass parts is more preferable. If it is less than 2 parts by mass, the mortar density cannot be sufficiently reduced, and if it exceeds 15 parts by mass, the fluidity may be adversely affected.

  The expansion material used in the present invention is used to reduce the curing shrinkage due to drying of the mortar, and is not particularly limited, but those such as Auin, calcium aluminoferrite, and lime are used. Can be mentioned.

  The amount of the expansion material used is usually preferably 1 to 10 parts by mass and more preferably 2 to 8 parts by mass with respect to 100 parts by mass of cement. If the amount is less than 1.0 part by mass, the effect of suppressing curing shrinkage is not sufficient, and even if the amount exceeds 10 parts by mass, the improvement in the effect is small.

The shrinkage reducing agent used in the present invention is not particularly limited, but is preferably a polyoxyalkylene derivative, the general formula of which is represented by X {O (AO) nR} m, and X is 2-8. A residue of a compound having a hydroxyl group, AO is an oxyalkylene group having 2 to 18 carbon atoms, R is a hydrogen atom, a hydrocarbon group having 1 to 18 carbon atoms, or an acyl group having 2 to 18 carbon atoms, n is 30 to 30 1000 and m are 2 to 8, and 60 mol% or more of the oxyalkylene group is composed of a polyoxyalkylene derivative which is an oxyethylene group.
When the value of n is less than 30, the melting point becomes low and it becomes difficult to use it in powder form. When the value of n exceeds 1000, the viscosity becomes high and the production becomes difficult.
If the oxyethylene group is less than 60 mol%, the melting point becomes low, making it difficult to use in powder form, and the solubility in the cement solution becomes poor.

  In the general formula X {O (AO) nR} m, X is a residue of a compound having 2 to 8 hydroxyl groups. Examples of the compound having 2 to 8 hydroxyl groups include ethylene glycol, propylene glycol, butylene glycol. , Hexylene glycol, styrene glycol, alkylene glycols having 8 to 18 carbon atoms, glycols such as neopentyl glycol, glycerin, diglycerin, polyglycerin, trimethylolethane, trimethylolpropane, 1,3,5-pentanetriol, Erythritol, pentaerythritol, dipentaerythritol, sorbitol, sorbitan, sorbide, condensates of sorbitol and glycerin, polyhydric alcohols such as adonitol, arabitol, xylitol, mannitol, or partially etherified products thereof, Or saccharides such as esterified products, xylose, arabinose, ribose, rhamnose, glycose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, raffinose, gentianose, melezitose, or partially etherified products thereof Examples include esterified products.

  In the general formula X {O (AO) nR} m, the oxyalkylene group having 2 to 18 carbon atoms represented by AO is converted to ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, α-olefin oxide having 6 to 18 carbon atoms, or the like. It is derived from oxyethylene group, oxypropylene group, oxybutylene group, oxytetramethylene group, oxyalkylene group of 6 to 18 carbon atoms, etc. Random addition may be used.

  In the above general formula, the hydrocarbon group having 1 to 18 carbon atoms represented by R is methyl group, ethyl group, allyl group, propyl group, isopropyl group, butyl group, isobutyl group, tertiary butyl group, amyl group, Isoamyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, isotridecyl, tetradecyl, hexadecyl, isocetyl, octadecyl, isostearyl, oleyl Benzyl group, cresyl group, butylphenyl group, dibutylphenyl group, octylphenyl group, nonylphenyl group, dodecylphenyl group, styrenated phenyl group and the like.

  Similarly, as the acyl group having 2 to 18 carbon atoms represented by R, acetic acid, propionic acid, butyric acid, isobutyric acid, caproic acid, caprylic acid, 2-ethylhexanoic acid, pelargonic acid, capric acid, lauric acid, myristic Examples include acyl groups derived from acids, palmitic acid, isopalmitic acid, margaric acid, stearic acid, isostearic acid, acrylic acid, methacrylic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid and the like.

  1-10 mass parts is preferable with respect to 100 mass parts of cement, and, as for the usage-amount of a shrinkage | contraction reducing agent, 2-8 mass parts is more preferable. If it is less than 1 part by mass, a sufficient shrinkage reduction effect cannot be obtained, and if it exceeds 10 parts by mass, strength development may be inhibited.

  The fluidizing agent used in the present invention is not particularly limited, and examples thereof include melamine-based, naphthalene-based, lignin-based, and polycarboxylic acid-based ones, and are used for adjusting the fluidity of mortar.

0.02-0.5 mass part is preferable with respect to 100 mass parts of cement, and, as for the usage-amount of a fluidizing agent, 0.06-0.3 mass part is more preferable. If the amount is less than 0.02 parts by mass, the effect of improving the fluidity may not be exhibited. If the amount exceeds 0.5 parts by mass, the fluidity may be too good, and dripping or rebound may increase.
Although the mixing method of the fluidizing agent of the present invention is not particularly limited, for example, it is preferable to disperse in cement or water in advance.

The air-entraining agent used in the present invention is used for the purpose of reducing the pressure resistance by lightening the kneaded mortar or further improving the freeze-thaw resistance by the effect of the entrained entrained air.
The type of air entraining agent is not particularly limited, and commercially available products can be used. For example, fatty acid soaps such as Vinsol, higher alcohol sulfate esters such as polyoxyethylene alkyl sulfate, ethers such as polyoxyethylene alkyl ether and polyoxyalkyl phenyl ether, ester ethers such as polyoxyethylene sorbitan oleate, Examples include betaines and imidazoline betaines.

  0.0005-0.05 mass part is preferable with respect to 100 mass parts of cement, and, as for the usage-amount of an air entraining agent, 0.001-0.02 mass part is more preferable. If the amount is less than 0.0005 parts by mass, the air mixing effect is small, and if the amount exceeds 0.05 parts by mass, the air mixing becomes excessive and the strength development may be adversely affected.

The setting accelerator used in the present invention is an agent that accelerates the setting of the mortar, and is an agent that accelerates the setting to such an extent that it does not hinder kneading and feeding the mortar.
Examples of the setting accelerator include lithium, sodium, potassium carbonate, bicarbonate, sulfate, silicate, hydroxide, formate, acetate, and the like. Of these, the use of lithium, sodium and potassium silicates and formates is preferred because they do not adversely affect mortar mixing and pumping.
Use in combination with a set retarder if it can be improved by using a set retarder such as an organic acid or phosphate even if it adversely affects kneading and pumping of the mortar by adding a set accelerator. Also good.

0.1-1 mass part is preferable with respect to 100 mass parts of cement, and, as for the usage-amount of a setting accelerator, 0.2-0.8 mass part is more preferable. Is less than 0.1 part by weight, the effect of promoting the condensation can not be sufficiently exhibited, and when it exceeds 1.0 part by weight, may adversely affect the kneading and pumping mortar.

The melt-spun basalt fiber used in the present invention is an amorphous artificial mineral fiber made from natural basalt and melt-spun at a high temperature. Its features are excellent heat resistance compared to organic fibers, superior chemical resistance compared to glass fibers and rock wool, and a density of about 2.8 g / cm ^3, which is similar to dry mortar and is uniformly mixed It is characterized by excellent properties.
The fiber diameter of the melt-spun basalt fiber is preferably 2 to 50 μm, and more preferably 7 to 20 μm. If it is smaller than 2 μm, it is difficult to produce stably, and if it exceeds 50 μm, the effect of reducing initial cracks may be reduced.
The fiber length of the melt-spun basalt fiber is preferably 2 to 15 mm, and more preferably 5 to 10 mm. If it is less than 2 mm, the effect of reducing initial cracks is small, and if it exceeds 15 mm, the dispersibility when mixed in dry mortar may deteriorate.
The melt-spun basalt fiber is not in a single fiber state in which the fibers are loosened (fiber diameter is 0.1 mm or more), but in a converged state in which single fibers with a fiber diameter of 50 μm or less are bundled with a sizing agent or the like. It is preferable to use one. By making it into a convergent state with moderate adhesive strength, it can be easily loosened and mixed evenly when mixed with dry mortar.

0.1-10 mass parts is preferable with respect to 100 mass parts of cement, and, as for the usage-amount of the melt-spun basalt fiber, 0.3-5 mass parts is more preferable. If it is less than 0.1 mass, the effect of reducing initial cracks cannot be expected, and if it exceeds 10 mass parts, uniform mixing may not be possible.
Moreover, in this invention, it is also possible to use together with fibers other than melt-spun basalt fibers, such as various organic fibers, carbon fibers, and steel fibers, within a range that does not affect performance.

  In the present invention, various cement admixtures such as an antifoaming agent, a water repellent and an antibacterial agent can be used in combination as necessary.

  The amount of water to be mixed with the spray material of the present invention is usually 10 to 22 parts by mass with respect to 100 parts by mass of mortar premixed with aggregate in consideration of the pumpability of the mortar, sprayability, and cured material properties. Is preferable, and 12 to 19 parts by mass is more preferable. If it is less than 10 parts by mass, it is difficult to ensure fluidity that can pump mortar, and if it exceeds 22 parts by mass, strength development may be reduced. If it is the range of 10-22 mass parts, it can adjust to moderate fluidity | liquidity suitable for pump pumping by using a fluidizing agent together.

  The spraying material construction method of the present invention is a method of mixing a spraying material and water, pumping the kneaded mortar with a pump, and joining and spraying compressed air in the middle of pumping. The method is not particularly limited.

  180 parts by mass of aggregate sand with respect to 100 parts by mass of cement, 6 parts by mass of lightweight aggregate with respect to 100 parts by mass of sand, and 5 parts by mass of expansion material with respect to 100 parts by mass of cement, a shrinkage reducing agent 3 parts by mass, 0.1 parts by mass of a fluidizing agent, 0.005 parts by mass of an air entraining agent, 0.5 parts by mass of a setting accelerator, 8 parts by mass of pozzolanic fine powder, 0.05 parts by mass of a polymer thickener, melting The dispersibility of the fiber was evaluated when dry-blown spray material with the blended amount of spun basalt fiber added as shown in Table 1. The pozzolanic fine powder was used after replacing the aggregate. For comparison, vinylon fibers were also similarly processed. The results are also shown in Table 1.

(Materials used)
Cement: Ordinary Portland cement, Commercial aggregate: Dry lime sand from Aomi, Niigata Prefecture, bulk density 1.62 g / cm ³ , maximum particle size 1.2 mm
Lightweight aggregate: Chinese fly ash balloon, bulk density 0.42 g / cm ³ , maximum particle size 0.8 mm
Expansion material: calcium sulfoaluminate-based expansion material, commercial product shrinkage reducing agent: polyoxyalkylene derivative, HO— (CH ₂ CH ₂ O) ₁₈₉ -H, commercial product fluidizing agent: methylolmelamine-based fluidizing agent, commercial product Air entrainer: Polyoxyethylene alkyl sulfate-based air entrainer, Commercially available set accelerator: Sodium silicate, Commercially available pozzolana fine powder: Blast furnace granulated slag, Blaine specific surface area 7500 cm ² / g, Commercially available polymer thickener : Hydroxyethylmethylcellulose, hydroxyethoxy group content 6%, translucency at 30 ° C. 55%, commercially available melt-spun basalt fiber: fiber diameter 10 μm, fiber length 6 mm, convergence type, commercially available vinylon fiber: fiber diameter 26 μm, Fiber length 6mm, convergence type, commercial product

(Test method)
Dispersibility of fibers: 30 kg of a spray material blended with cement fibers was put into a tilting mixer having a capacity of 50 liters and stirred for 15 minutes. The obtained dry mixture was transferred to a 1 m ² square container and divided into 9 parts so as to have the same area. 500 g was sampled from each divided portion, the dry mixture was sieved with a 2.5 mm sieve, the mass of the fiber remaining on the sieve was measured, the coefficient of variation was calculated from the average value and the standard deviation, and the dispersibility was evaluated.
Appearance: When transferred to a square container, it was visually observed to confirm the presence or absence of fiber balls (fibers entangled without being dispersed).

  From Table 1, it can be seen that the spray material of the present invention is uniformly dispersed even if the amount of the fiber used is large.

  Each fiber used in Example 1 was added in the amount shown in Table 2, and dry mortar was prepared in the same manner as in Example 1. Water is added to 16.5 parts by mass with respect to 100 parts by mass of the dry mortar, and the mixture is kneaded with a pan-type mixer to form cement mortar. This is pumped with a squeeze pump, and compressed air is joined before the discharge nozzle. It sprayed so that it might become thickness 1cm on the concrete flat plate of width 30cm x length 30cm x thickness 6cm. The test specimen that had been sprayed was confirmed to be cracked after one day in a state where the humidity was 60%, the temperature was 5 ° C., and a wind of 1 to 3 m was applied by a blower. The results are also shown in Table 2.

(Test method)
Crack status: The total crack length was measured along the cracks that occurred.

  From Table 2, it can be seen that according to the spraying material of the present invention and the spraying method using the same, a mortar having excellent crack resistance can be obtained.

  Add 0.3 parts by mass of basalt fiber melt-spun with respect to 100 parts by mass of cement, and add the amount of pozzolanic fine powder, holmite mineral, and polymer thickener shown in Table 3 to 100 parts by mass of cement. Except that, dry mortar was prepared in the same manner as in Example 1. Water is added to 16.5 parts by mass with respect to 100 parts by mass of the dry mortar, and the mixture is kneaded with a pan-type mixer to form a cement mortar. The rebound rate and thickness were measured by spraying. The results are also shown in Table 3.

(Materials used)
Holmite mineral: attapulgite, crystalline silica content less than 1%, commercial product

(Test method)
Flowability: A flow test defined in JIS R 5201 was performed.
Rebound rate: Percentage of material dropped when sprayed on concrete precast plate installed on ceiling for 2 minutes and total mortar amount used for spraying.
Thickness: Thickness was evaluated when sprayed on a concrete U-shaped side groove lid of length 400 mm × width 600 mm × thickness 60 mm to a thickness of 90 mm. The presence or absence of falling or floating 24 hours after spraying was confirmed. If it did not fall or float, it was rated as ○.

  From Table 3, it can be seen that according to the spraying material of the present invention and the spraying method using the same, a mortar having a low rebound rate and excellent thickness can be obtained.

  With the spraying material of the present invention and the spraying method using the same, it is possible to thicken by one spraying and to shorten the construction time. Further, by blending a specific fiber, it is excellent in uniform mixing property when mixed with dry mortar, and more excellent initial crack resistance can be imparted. Therefore, it can be widely applied to repair work in the civil engineering and construction fields.

Claims (7)

Cement, pozzolanic fine powder, polymer thickener and / or holmite mineral, aggregate sand, lightweight aggregate, expansion material, shrinkage reducing agent, fluidizing agent and / or air entraining agent When a setting accelerator, fiber diameter was melt spinning 2 to 50 [mu] m, fiber length and also contains a basalt fiber convergence state is 2 to 15 mm, with respect to 100 parts by weight of cement, pozzolana fine powder 3 -20 parts by mass, polymer thickener 0.02-0.5 parts by mass, holmite-based mineral 0.02-5 parts by mass, fluidizer 0.02-0.5 parts by mass, setting accelerator 0.1 to 1 part by mass, 0.1 to 10 parts by mass of melt-spun basalt fiber, and 2 to 15 parts by mass of lightweight aggregate with respect to 100 parts by mass of sand . 2 to 15 parts by mass of lightweight aggregate having a bulk density of 0.7 g / cm ³ or less with respect to 100 parts by mass of sand, with respect to 100 parts by mass of cement. The spraying material described. The spray material according to claim 1 or 2, wherein the polymer thickener is hydroxyethyl methylcellulose. The spray material according to any one of claims 1 to 3, wherein a holmite mineral having a crystalline silica content of 1% by mass or less is used. The shrinkage reducing agent is a powdered polyoxyalkylene derivative, the general formula of which is represented by X {O (AO) nR} m, X is a residue of a compound having 2 to 8 hydroxyl groups, and AO has 2 carbon atoms. -18 oxyalkylene group, R is a hydrogen atom, a C1-C18 hydrocarbon group, or a C2-C18 acyl group, n is 30-1000, m is 2-8, The spraying material according to any one of claims 1 to 4, wherein 60 mol% or more is an oxyethylene group. A spraying method in which the spraying thickness per layer is 90 mm or more using the spraying material according to claim 1. Concrete repaired using the spray material according to any one of claims 1 to 5.