JP5713540B2 - Spraying method of ultra high strength fiber reinforced mortar and cured mortar - Google Patents

Description

  The present invention mainly relates to a method for spraying ultra-high-strength fiber reinforced mortar and a mortar cured body used in the civil engineering and construction industries.

  The problem with mortar and concrete is that the bending strength is basically lower than the compressive strength, and even if the compressive strength is increased, the bending strength is not so high. Conventionally, in order to increase the bending strength, a method of introducing prestress with PC steel, a method of introducing chemical prestress with an expanding material, a method of reinforcing with metal fibers, and a steel tube filled with high-strength mortar or concrete A method of making a composite structure has been implemented.

With regard to a cement composition that is reinforced with metal fibers and exhibits a high bending strength and a cement-based cured body using the same, for example, cement, a pozzolanic material having an average particle size of less than 1.5 μm, an average particle size of 1.5 A cement having a compressive strength of 1500 kgf / cm ² (147 N / mm ² ) and a bending strength of 150 kgf / cm ² (14.7 N / mm ² ) or more using a cement composition composed of quartz powder of 20 μm and aggregate and metal fibers. A system hardening body is obtained (refer patent document 1).
Ultra high strength fiber reinforcement containing cement, silica fume, coal gasified fly ash, gypsum, and metal fibers, and the ratio of silica fume and coal gasified fly ash is 95-50 parts: 5-50 parts by mass ratio Proposals have also been made regarding cement compositions and ultrahigh strength fiber reinforced mortar or concrete containing fine aggregates in the cement composition. (See Patent Document 2)
Materials aimed at improving mechanical properties such as tensile strength include blending a large amount of vinylon short fibers, kneading concrete or mortar, and orienting the short fibers in a three-dimensional random orientation. Materials that improve the bending strength are also known (see Patent Documents 3 to 8).

  Coal gasified fly ash is discharged as a by-product when power is generated using gasified coal, and the spherical particles have a smaller average particle size than ordinary pulverized coal-fired fly ash. Furthermore, since the spherical particle surface of coal gasification fly ash is smooth, it has better ball bearing action than ordinary fly ash, and it can be used for high strength mortar or concrete with high fluidity at a low water binder ratio. It has already been proposed (see Patent Document 9).

  Gypsum is frequently used as a high-strength admixture regardless of the presence or absence of steam curing, and has been proposed as an admixture that can obtain higher strength and durability when combined with silica fume (see Patent Document 10).

JP-A-11-130508 JP 2006-298679 A JP 2000-7395 A JP 2002-193653 A JP 2005-238605 A Japanese Patent Laying-Open No. 2005-305682 JP 2005-1965 A JP 2006-2104080 A JP 2001-19527 A Japanese Patent No. 2581803

In the present invention, conventionally known silica fume, coal gasification fly ash, gypsum, and fibers are combined in a specific range, and the compressive strength of the mortar hardened body on-site curing is 150 N / mm ² or more by the spraying method. The bending strength is 20 N / mm ² or more, and the bending strength / compression strength ratio is 1/9 or more.

In the present invention, (1) the mixing ratio of silica fume and coal gasification fly ash is 5 to 50 parts by mass of coal gasification fly ash with respect to 95 to 50 parts by mass of silica fume, and the total amount of silica fume and coal gasification fly ash is A binder composed of cement, silica fume, coal gasified fly ash, and gypsum, in which the binder is 5 to 40% by mass, and gypsum is 0.5 to 8 parts by mass in terms of anhydride with respect to 100 parts by mass of cement; 50 to 200 parts by mass of fine aggregate with respect to 100 parts by mass of the binder, and fibers of 5 to 30 mm in length of 0.5 to 3% by volume with respect to 1 m ^{3 of} mortar composed of the binder, fine aggregate and water. Mortar that pumps ultra-high-strength fiber reinforced mortar obtained by kneading water and water, and discharges per hour when the compressor air pressure is 0.4 MPa or more ^(M 3 / hr) compressive strength of the mortar cured body obtained by blowing using compressed air which is 40 times or more of the air flow rate ^(m 3 / hr) with respect to the 150 N / mm ² or more, a bending strength of 20 N / in mm ² or more, bending strength / compressive strength ratio Ri der 1/9 or more, mortar cured body of the ultra high strength fiber reinforced mortar compressive strength of the mortar cured body is kneaded to prepare in accordance with JIS R 5201 spraying method of compressive strength ratio to the compression strength is equal to or greater than 1.0, (2) ultra high strength fiber-reinforced mortar was pumped, merging mixing a curing accelerator other than the compressed air in the middle spraying method of the spraying in (1), it is.

According to the spraying method of the ultra-high-strength fiber reinforced mortar of the present invention, it has fluidity (workability) suitable for spraying construction, the compressive strength of the cured mortar body is 150 N / mm ² or more, bending The compressive strength of a cured mortar produced by applying the ultra-high strength fiber reinforced mortar having a strength of 20 N / mm ² or more, a bending strength / compression strength ratio of 1/9 or more, and kneading according to JIS R 5201. On the other hand, an ultra-high strength fiber reinforced mortar cured body having a compressive strength ratio exceeding 1.0 is obtained.

The present invention will be described in detail below.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.

  The cement used in the present invention is normal, early strong, moderate heat, low heat, sulfate resistance, white and other various Portland cements, mixed blast furnace slag and normal fly ash mixed with Portland cement, ecocement, These are super early-strength cement and quick-hardening cement. A cement obtained by mixing an arbitrary amount of a plurality of these cements can also be used. In addition, ordinary Portland cement, early-strength Portland cement, blast furnace slag cement and the like suitable for producing ettringite are more preferable.

Silica fume used in the present invention is spherical ultrafine particles by-produced when a silicon alloy such as metallic silicon or ferrosilicon is produced in an electric furnace or the like, and the main component is amorphous SiO ₂ . Addition of silica fume increases the compressive strength of the hardened cement body, but the ratio of the bending strength to the compressive strength may be lower than when it is not mixed. Furthermore, since silica fume is spherical ultrafine particles, when it is used in combination with a high-performance water reducing agent or the like, good fluidity can be obtained in the cement kneaded material.

As described above, the coal gasification fly ash (hereinafter abbreviated as CGFA) used in the present invention is discharged as a by-product when power is generated using gasified coal. The largest particles that are discarded together from the boiler flue and collected by the dust collector are spherical fine particles of 5 to 10 μm. In addition, it differs from ordinary coal-fired fly ash in that the particle diameter and particle surface properties are different and the SiO ₂ content is high. Since CGFA has a spherical particle size like silica fume, it has an effect of enhancing fluidity when used in combination with a high-performance water reducing agent, but its strength enhancement effect is small because pozzolanic activity is lower than that of silica fume.

In this invention, it is preferable to mix | blend in the ratio of 95-50 parts of silica fume and 5-50 parts of CGFA. By mixing at this specific ratio, it becomes possible to synergistically increase the fluidity of the cement kneaded material and the bending strength of the cemented body.
If the CGFA is less than 5 parts, the effect of improving the fluidity and bending strength is small, and if it exceeds 50 parts, the compressive strength is lowered. As for the blending ratio of CGFA to silica fume, as the CGFA increases, both the fluidity and the bending strength are improved. However, when the peak value is exceeded, the improvement effect decreases as the amount of CGFA increases.
Therefore, the more preferable ranges of the mixing ratio of silica fume and CGFA are 90-60 parts of silica fume and 10-40 parts of CGFA.
A specific ratio of silica fume and CGFA is added in a total amount of 5 to 40 parts per 100 parts of cement. If it is less than 5 parts, the improvement of fluidity and the effect of enhancing strength against compressive strength and bending strength are small, and if added over 40 parts, the fluidity is lowered and at the same time the effect of enhancing strength according to the addition rate cannot be expected. It is not preferable in terms of performance and economy. A more preferable range is 7 to 30 parts.

Furthermore, the gypsum used in the present invention is gypsum in various forms such as dihydrate gypsum, hemihydrate gypsum, soluble anhydrous gypsum (type III), and insoluble anhydrous gypsum (type II), but more preferably anhydrous gypsum. It is plaster. In the initial stage of hydration, gypsum temporarily suppresses hydration of calcium aluminate to increase fluidity, and then generates ettringite in the form of needles by a hydration reaction. This ettringite fills the voids in the hardened cement body and promotes solidification, thereby enabling high strength.
Gypsum is blended in 0.5 to 8 parts in terms of anhydride with respect to 100 parts of cement. If it is less than 0.5 part, the effect of increasing fluidity and strength is small, and even if it exceeds 8 parts, it will be stronger. Can not be expected. Preferably it is 1-5 parts.

The fine aggregate used in the present invention is preferable because river sand and crushed sand used in ready-mix factories are most readily available, but is not particularly limited. There are no restrictions on the use of high-hardness calcined bauxite, iron ore, quartz porphyry or other fine aggregates to obtain higher strength. Further, it is not necessary to use a special particle size configuration such as reducing the maximum aggregate size, but the maximum aggregate size may be limited depending on the purpose and application. Usually, the grain size configuration prescribed by the Japan Society of Civil Engineers and Architectural Institute is sufficient.
The fine aggregate is blended in an amount of 50 to 300 parts with respect to 100 parts of cement, silica fume, CGFA and gypsum (hereinafter simply referred to as a binder). If it is less than 50 parts, the hardened cement body may show brittle properties and the bending strength may be reduced. If it exceeds 300 parts, it will be difficult to obtain a compressive strength of 150 N / mm ² or more even if the high-performance water reducing agent is utilized to the maximum extent. A more preferable range is 60 to 150 parts.
Furthermore, any amount of coarse aggregate can be used in combination. The quality of the coarse aggregate is not particularly limited as in the case of the fine aggregate, and those used in the ready-mixed factory can be used.

The curing accelerator used in the present invention is an agent that accelerates the curing of mortar and concrete obtained by kneading, imparts plasticity, and can be thickened by adding and spraying in the middle of pumping. Is granted. If the curing accelerator is not added, the spraying thickness of one time is about 20 mm, but by adding the curing accelerator, the thickness can be increased to about 300 mm.
The type of the curing accelerator is not particularly limited as long as it accelerates the setting of cement and can secure a compressive strength of 150 N / mm ² or more and a bending strength of 20 N / mm ² or more. Examples thereof include commercially available calcium aluminate accelerators, calcium sulfoaluminate accelerators, aluminate accelerators, aluminum sulfate accelerators, and silicate accelerators.
In addition, as an agent for imparting plasticity, an acrylate polymer compound or a clay mineral can also be used. As the curing accelerator, both powder and liquid can be used.
0.1-10 parts are preferable with respect to 100 parts of cement, and, as for the usage-amount of a hardening accelerator, 0.5-6 parts are more preferable. If the amount is less than 0.1 part, the thickening property may not be exhibited. If the amount exceeds 10 parts, strength development may be inhibited.

When producing the ultra-high-strength fiber reinforced mortar of the present invention, 15 to 25 parts (hereinafter simply referred to as a water ratio) is blended with 100 parts of the binder in the total amount of the kneaded water and the high-performance water reducing agent. Is preferred. However, the high-performance water reducing agent in this case indicates a water reducing agent that is commercially available in a liquid state regardless of the solid content concentration. When using a high-performance water reducing agent marketed in powder form, it is not included in 15 to 25 parts.
If the mixing water is less than 15 parts, it is difficult to obtain good fluidity even if the amount of fine aggregate is reduced and the mass reduction ratio of the high-performance water reducing agent is maximized. Strength cannot be obtained.
Examples of the high-performance water reducing agent that can be used in the ultrahigh-strength fiber reinforced cement composition of the present invention include those referred to simply as high-performance water reducing agents and those referred to as high-performance AE water reducing agents.
The type and blending amount of the high-performance water reducing agent are not particularly limited, but any type of high-performance water reducing agent is used in a liquid state of 5 parts at most for 100 parts of cement, preferably 4 parts. It is. Even if the amount exceeds 5 parts, the water reduction rate cannot be increased in many cases. In the case of powder, it is at most 3 parts, preferably 2 parts.

High performance water reducing agents are polyalkylallyl sulfonate high performance water reducing agents, aromatic amino sulfonate high performance water reducing agents, melamine formalin sulfonate high performance water reducing agents, and polycarboxylate salts. One of the water-reducing agents is used as a main component, and one or more of these are used. Polyalkylallyl sulfonate-based high-performance water reducing agents include methyl naphthalene sulfonic acid formalin condensate, naphthalene sulfonic acid formalin condensate, and anthracene sulfonic acid formalin condensate. Although it has the characteristic that the setting delay is small, it has a problem that the flow and slump retention are small.
As commercial products, trade name “FT-500” of Electrochemical Industry Co., Ltd. and its series, trade names “Mighty 100 (powder)” and “Mighty 150” and its series of Kao Corporation, Daiichi Kogyo Seiyaku Representative are the trade name “Cellflow 155”, the product name “Pole Fine MF”, and the product name “Flolic PS” and the series thereof. Aromatic amino sulfonate-based high-performance water reducing agents include the product name “Floric VP200” and its series of Floric Co., Ltd., and melamine formalin resin sulfonate-based high-performance water reducing agents include Grace Chemicals. Product names “Darlex FT-3S”, Showa Denko Construction Materials Co., Ltd. product names “Molmaster F-10 (powder)” and “Molmaster F-20 (powder)” may be mentioned.
High-performance AE water-reducing agents include polyalkylallyl sulfonate-based high-performance water-reducing agents, aromatic amino sulfonate-based high-performance water-reducing agents, and melamine formalin resin sulfonate-based improved types. It may mean a carboxylate-based water reducing agent. The polycarboxylate-based water reducing agent is a copolymer or a salt thereof containing an unsaturated carboxylic acid monomer as a component, for example, a copolymer of polyalkylene glycol monoacrylate, polyalkylene glycol monomethacrylate, maleic anhydride and styrene. Polymers, copolymers of acrylic acid and methacrylate, and copolymers derived from monomers copolymerizable with these monomers are the mainstream, and the amount added is lower than that of high-performance water reducing agents. The water reduction rate is large. In general, it has air entrainment properties and a large delay in setting and curing, but it has characteristics of good flow and slump retention.
Commercially available products include NM Co., Ltd. product name “Leo Build SP8N, 8HU” series, Floric Co., Ltd. product name “Flolic SF500S” series, Takemoto Yushi Co., Ltd. product names “Tupole HP8”, “Tupor” "HP11" series, Grace Chemicals Co., Ltd. trade names "Darlex Super 100", "Darlex Super 200", "Darlex Super 300", "Darlex Super 1000" series, Kao Corporation trade name "Mighty" 3000 "," Mighty 21WH "," Mighty 21WH "series and others are commercially available.

The fibers used in the ultra-high-strength fiber reinforced mortar of the present invention are fibers having a length of 5 to 30 mm and a diameter of 0.05 to 1 mm, and are blended in an amount of 0.5 to 3% by volume per 1 m ^{3 of} mortar. The When the length exceeds 30 mm, the fluidity of the mortar is lowered, and as a result, the improvement in bending strength is not great. Moreover, since it will become shorter than the maximum dimension of a fine aggregate if less than 5 mm, the fiber reinforcement effect at the time of a bending stress action will become small, and bending strength will fall. Preferably it is 8-20 mm.
Examples of the types of fibers include vinylon fibers, acrylic fibers, polyethylene fibers, polypropylene fibers, nylon fibers, aramid fibers, carbon fibers, glass fibers, and steel fibers. From the viewpoint of strength, it is preferable to use vinylon fiber, aramid fiber, carbon fiber, or metal fiber.
If the fiber diameter is less than 0.01 mm, the strength of the fiber itself becomes weak, so the bending strength may be difficult to improve. If the fiber diameter exceeds 1 mm, the number of fibers per unit volume in the mortar of the fiber even if the blending amount is increased. Therefore, the bending strength is not improved.
The blending amount of the fibers is 0.5 to 3% by volume in 1 m ³ of the mortar, and the effect of improving the bending strength is small if the amount is less than 0.5% by volume. The increase according to the mixing ratio is not large. Preferably it is 0.7-2.5 volume%.

  The mixing method of the ultra high strength fiber reinforced mortar of the present invention may be a conventional mixing method. In addition, when using a forced kneading type mixer, it is preferable to add the fiber to the mixer when fluidity appears in the mortar and knead again. Moreover, you may use the thing of the state disperse-mixed previously with dry mortar.

  In the present invention, blast furnace slag fine powder, blast furnace slow-cooled slag fine powder, expansion material, antifoaming agent, thickener, rust inhibitor, antifreeze agent, shrinkage reducing agent, water retention agent, pigment, polymer emulsion, hydrotalcite It is possible to use together 1 type (s) or 2 or more types in the group which consists of anion exchangers, various additives, limestone fine powder, etc. in the range which does not inhibit the objective of this invention substantially.

The spraying method of the present invention is not particularly limited, and a commonly used facility can be used. For example, a piston pump, a squeeze pump, a snake pump, or the like can be used as a pump for pumping the kneaded mortar.
A pressure hose of 2 MPa or more is usually used as a hose for pressure feeding. The pumping distance is not particularly limited, but it depends on the capacity of the pump and the diameter of the hose, but about 50 m is the maximum considering the loss in the hose and the trouble at the time of closing.
The spray nozzle is not particularly limited, and a commercially available one can be used. Even when a curing accelerator is used in combination, commercially available products can be used. When the curing accelerator is combined, if it is liquid, it is combined with the mortar that is pumped using a pump, but the type of the pump is not particularly limited, and a squeeze pump or a plunger pump can be used. The use of a plunger pump is preferred because it can be pumped while being pressurized. When using a powder hardening accelerator, an additive system capable of air-feeding the powder may be used. For example, there is a system such as “Natom Cleat”, a powder air transportation device manufactured by Denki Kagaku Kogyo. As a method of adding a curing accelerator, in the case of a liquid, the liquid may be pumped and mixed in a mortar that is directly pumped, or mixed with compressed air and mixed in a mist before mixing with the mortar. Also good. In the case of powder, since it is an air conveyance system, compressed air and powder hardening accelerator are mixed.
The compressed air used for the spray construction preferably has a compressor air pressure of 0.4 MPa or more. If it is less than 0.4 MPa, the compressive strength ratio of the sprayed mortar may be less than 1.0. It is necessary to change the air flow rate of the compressed air used for spraying according to the discharge amount of mortar. When changing, it is possible to adjust the flow rate by changing the type of the compressor or providing a valve before the compressed air joins with the mortar to which the compressed air is pumped. In general, an air flow rate (m ³ / hr) that is 40 times or more the mortar capacity (m ³ / hr) discharged per hour is preferable. If it is less than 40 times, the compression strength ratio of the sprayed mortar may be less than 1.0.

  The curing method of the ultra-high-strength fiber mortar of the present invention is not limited, and a normal curing method can be used in place, a steam curing, an autoclave curing, a hot water curing, and the like in a product factory.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, it is not restricted to these.

  The materials, test items, and methods used in the examples are summarized below.

(Materials used)
Cement: manufactured by Denki Kagaku Kogyo KK, ordinary Portland cement, density 3.16 g / cm ³
Fine aggregate: River sand from Himekawa, Niigata Prefecture, 5mm or less, density 2.62g / cm ³
SF: Silica fume, manufactured by Elchem, density 2.44 g / cm ³
CGFA: Dutch coal gasification fly ash, density 2.44 g / cc
Gypsum: Insoluble anhydrous gypsum, natural product, density 2.82 g / cm ³
High performance water reducing agent: Polycarboxylate water reducing agent, "Super 1000N" manufactured by Grace Chemicals Co., Ltd.
Fiber A: Steel having a diameter of 0.2 mm and a length of 15 mm, tensile strength 2000 N / mm ² , density 7.80 g / cm ³
Fiber B: Vinylon fiber having a diameter of 0.2 mm and a length of 12 mm, a tensile strength of 1600 N / mm ² , and a density of 1.3 g / cm ³
Fiber C: aramid fiber having a diameter of 0.012 mm and a length of 12 mm, a tensile strength of 3500 N / mm ² , and a density of 1.39 g / cm ³
Fiber D: Carbon fiber having a diameter of 0.05 mm and a length of 12 mm, a tensile strength of 4000 N / mm ² , and a density of 1.8 g / cm ³

(Test method)
Mixing of mortar and measurement of flow: According to JIS R 5201. The flow was a static flow value (mm) when the flow was extracted.
Pumpability: When the mixed mortar is pumped with a squeeze pump with a pressure hose with an inner diameter of 40 mm and 20 m mortar with a discharge rate of 0.5 m ³ / hr, if the pumping pressure exceeds 2.5 MPa, the pumping load is judged to be large. However, if it was smaller than that, it was judged that the pressure load was small.
Method of measuring mortar strength: Bending strength and compressive strength were measured according to JIS R 5201. The mortar was molded by spraying directly onto a 4 × 4 × 16 cm triple form. The curing method is that the molded ultra-high-strength fiber mortar specimen is immediately sealed in a constant temperature room at 20 ° C with a vinyl sheet, then demolded the next day, cured at 20 ° C in water, and subjected to a strength measurement test at a specified age. Carried out.
Abrasion amount: Measured according to JIS K 7204. The specimen for the wear test is φ10 × 1 cm. The curing method is the same as the strength test. The wear conditions are a load of 1000 g and a rotation speed of 1000 rpm.

"Example 1"
100 parts of fine aggregate, 19 parts of water (including 1.5 parts of water reducing agent for the binder), 100 parts of binder, and 100 parts of binder made of cement, silica fume, coal gasified fly ash and gypsum Mixing ratio of fiber A to 0.8% by volume with respect to 1m ^{3 of} mortar made of fine aggregate and water, each compounding to the total of silica fume (SF) and coal gasification fly ash (CGFA) in the binder The ratio (%) and the total amount of these ingredients in the binder (%) and the gypsum binder ratio (%) are arbitrarily changed, and ultra-high-strength fiber mortar is kneaded for 5 minutes with a Damacut mixer. Then, 20 m mortar was pumped at a discharge amount of 0.5 m ³ / hr with a pressure hose having an inner diameter of 40 mm with a squeeze pump. In front of the nozzle outlet, compressed air having an air pressure of 0.7 MPa and an air flow rate of 0.6 m ³ / min was introduced and sprayed to prepare a mortar specimen, and the compressive strength and bending strength were measured. The results are shown in Table 1. In addition, it measured also about the mortar test piece produced by packing and forming in the mold without spraying the mortar which kneaded.

"Example 2"
The mortar having the composition of Experiment No. 1-16 of Example 1 was pumped, and compressed air and a curing accelerator were mixed with 100 parts of cement as shown in Table 2 before the spray nozzle. The results are shown in Table 2.

(Materials used)
Curing accelerator A: Aluminum sulfate-based liquid curing accelerator, main component: aluminum sulfate, solid content 22%
Curing accelerator B: Calcium sulfoaluminate powder curing accelerator, trade name: Natomic T-10
Curing accelerator C: Silica salt-based liquid curing accelerator, lithium silicate aqueous solution, solid content 20%
Curing accelerator D: acrylate copolymer emulsion liquid curing accelerator, solid content 5%

(Test method)
Thickness: A vertical surface made of sprayed concrete was used, and the distance between the nozzle and the sprayed surface was set to 30 cm and fixed at a right angle for spraying. The thickness until the sprayed mortar peeled off was measured.

According to the spraying method of the ultra-high-strength fiber reinforced mortar of the present invention, it has fluidity (workability) suitable for spraying construction, the compressive strength of the cured mortar body is 150 N / mm ² or more, bending The compressive strength of a cured mortar produced by applying the ultra-high strength fiber reinforced mortar having a strength of 20 N / mm ² or more, a bending strength / compression strength ratio of 1/9 or more, and kneading according to JIS R 5201. On the other hand, an ultra-high-strength fiber reinforced mortar hardened body having a compressive strength ratio exceeding 1.0 can be obtained, so structural members for bridges, bridge accessories, underground structural members, dam structural members, marine structural members, building structural members It can be used for building construction materials, civil engineering construction materials and water use structural members that require wear resistance.

Claims (2)

The blending ratio of silica fume and coal gasification fly ash is 5 to 50 parts by mass of coal gasification fly ash with respect to 95 to 50 parts by mass of silica fume, and the total amount of silica fume and coal gasification fly ash is 5 to 40 mass in the binder. %, Gypsum is 0.5 to 8 parts by mass in terms of anhydride with respect to 100 parts by mass of cement, and a binder composed of cement, silica fume, coal gasified fly ash and gypsum, and 100 parts by mass of the binder 50 to 200 parts by mass of fine aggregate, 0.5 to 3% by volume of fibers of 5 to 30% in length with respect to 1 m ^{3 of} mortar composed of the binder, fine aggregate and water, and water. Pumping ultra-high-strength fiber reinforced mortar obtained by mixing, 40 times or less of mortar capacity (m ³ / hr) discharged per hour at an air pressure of 0.4 MPa or more The mortar hardened body obtained by spraying with compressed air having the above air flow rate (m ³ / hr) has a compressive strength of 150 N / mm ² or more, a bending strength of 20 N / mm ² or more, and a bending strength / compressive strength ratio. Ri der but 1/9 or more, the compressive strength ratio to the compressive strength of the mortar cured body mortar cured body compressive strength of the ultra high strength fiber reinforced mortar kneading was prepared in accordance with JIS R 5201 of 1 A spraying method characterized by exceeding 0.0 . 2. The spraying method according to claim 1, wherein the ultra-high-strength fiber reinforced mortar is pumped and the curing accelerator is mixed and sprayed in addition to the compressed air.