JP2014141370A - Hydraulic material and cured material of hydraulic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic material capable of forming a cured material excellent in compression strength, strength to tensile stress and toughness, and to provide a cured material of the hydraulic material excellent in both compression strength and tensile strength.SOLUTION: The hydraulic material comprises: a binder; an aggregate; a macro reinforcing steel fiber having a straight line part, first hook parts bent from both end parts of the straight line part to each have an angle with the straight line part, and second hook parts that are formed by bending end part of each first hook part in the direction away from each other so as to be parallel to the straight line part; one or more meso-reinforcing fibers selected from an organic fiber and an inorganic fiber; and a micro-reinforcing material selected from wollastonite and mica.

Description

  The present invention relates to a hydraulic material and a cured hydraulic material obtained by curing the hydraulic material.

Hydraulic materials applied to civil engineering and building structures, especially hydraulic materials such as cement, mortar and concrete, are used for various purposes. Hardened materials of hydraulic materials have a high compressive strength, so that It is used widely. However, the cured hydraulic material does not have sufficient tensile strength with respect to excellent compressive strength, and in structures such as reinforced concrete, concrete bears only compressive force and is designed in a usage mode that does not bear tensile force. It was common.
For the purpose of improving the tensile strength, conventionally, reinforcing steel fibers have been mixed with hydraulic materials, and deformed steel fibers, for example, both ends have been deformed in order to further improve resistance to pulling force. Techniques for adding hook-type steel fibers and linear steel fibers (for example, see Patent Document 1), techniques for adding steel fibers and wollastonite (for example, see Patent Document 2), and the like have been proposed. .

  In recent years, improvements have been made to improve the compressive strength of hardened hydraulic materials typified by hardened concrete. In particular, the ratio of water to binder in the hydraulic material, that is, concrete is taken as an example. And a mass ratio (hereinafter, referred to as a water / binder ratio) of a material that hydrates in concrete such as cement, silica fume, blast furnace slag, fly ash, etc. Various techniques have been proposed to increase the strength by reducing the weight (which is based on mass). This is because when the water / binder ratio is reduced, the distance between the particles is reduced, and the hydrated product is precipitated and filled in the liquid phase portion, so that the structure becomes dense and concrete with high compressive strength is obtained. It is thought that it is.

If a cement hardened body with high compressive strength is obtained, the column cross-section of the structure can be reduced, or the load area of the column load can be increased, which makes it useful for the construction of high-rise structures, In addition, the space between the pillars of the building can be increased, and the degree of freedom in the floor plan of the building can be increased, resulting in a great merit. On the other hand, higher tensile strength is also required.
When the compressive strength of the hardened hydraulic material is high, for example, when the compressive strength is 60 N / mm ² or more, the tensile strength may not be effectively improved even if the steel fibers used in the past are used as they are. I came.

Japanese Patent No. 3874509 JP-A-11-246255

Usually, it is considered that the reinforcing fiber such as steel fiber exerts the reinforcing effect because the stress acting on the cured body is dispersed in the reinforcing fiber through the adhesive force.
As a result of detailed examinations by the present inventors, when the tensile stress increases and the deformation of the cured body proceeds, if the strength of the cured body is not sufficiently high, the reinforcing fibers escape while breaking the cured body. Although there is a tendency, when the water / binder ratio is small and the compressive strength of the hardened hydraulic material is 60 N / mm ² or more, the hardened body is not destroyed, and the steel fibers themselves are pulled out by plastic deformation. Since the ratio of the steel fibers to be increased increases, it has been found that the resistance to tensile stress cannot be sufficiently obtained with the conventionally known steel fibers simply by selecting from the deformed fibers and the straight fibers. Further, according to the studies of the present inventors, in order to rationally design structure, the compressive strength of normal concrete at least the concrete hardened body is from 20 N / mm ² and 30 N / mm ^2, the 2 Tensile strength equivalent to a fraction is necessary to rationally construct a design structure. To prevent the structure from being brittlely destroyed, a predetermined yield strength is required even at 2% deformation. Found that it must be possible to hold. In the technique using steel fibers added to the cementitious matrix disclosed in Patent Document 2 and using a reinforcing material such as wollastonite, toughness is improved as compared with conventional products. However, although the improvement in the outermost edge stress (fracture coefficient) obtained mainly by dividing the bending moment by the bending test by the section modulus is remarkable, the tensile strength by the direct pulling test method is 10 N / mm. ^As a result of the examination by the present inventors, it is not possible to achieve a high tensile strength and a high toughness of ² or more, and it is about 12 MPa when post-tension that introduces a compressive force with a steel material in advance. It was. In addition, there is a problem that the explosion resistance characteristic of a molded article having a high compressive strength is not sufficient, and there is a demand for further improvement as a material for constructing a structure.

The subject of the present invention in consideration of the problems of these prior arts is not only the compressive strength, even in the case of reducing the water / binder ratio for the purpose of improving the compressive strength of the cured body in the hydraulic material, It is an object of the present invention to provide a hydraulic material capable of forming a cured hydraulic material with improved tensile strength and toughness.
Moreover, the further subject of this invention is providing the hydraulic material hardening body which is excellent in both the compressive strength and the tensile strength which uses the hydraulic material of the said invention.

As a result of intensive studies, the inventors of the present invention have found that when the strength of the cured hydraulic material is high, the addition of only the conventional reinforcing steel fibers cannot provide a sufficient improvement in tensile strength. By adding linear reinforcing materials such as steel fibers and organic fibers, as well as reinforcing materials that may have a chemical effect, the friction resistance and plastic deformation energy of the reinforcing fibers and the physical properties of the cured body itself are improved. Thus, the present inventors have found that the compressive strength, tensile strength, and toughness of the cured hydraulic material can be improved and the above problems can be solved.
That is, the configuration of the present invention is as follows.
<1> The first hook part and the end part of the first hook part that are bent so as to have an angle with the linear part from both ends of the binding material, the aggregate, the linear part and the linear part are folded in a direction away from each other. Macro reinforcing steel fiber having a second hook portion bent and parallel to the straight portion, one or more meso reinforcing fibers selected from organic fibers and inorganic fibers, and a micro reinforcing material selected from wollastonite and mica Hydraulic material containing
Here, the macro-reinforced steel fiber is a double-end hook-type steel fiber and is effective for reinforcing the macro region. One or more types of meso reinforcing fibers selected from organic fibers and inorganic fibers are effective reinforcing fibers for reinforcing the meso region, and may be simply referred to as “meso reinforcing fibers” hereinafter. The meso reinforcing fiber in the present invention is selected from fibers having a shape that does not have hook portions at both ends. The micro-reinforcing material selected from wollastonite and mica used in the present invention is a reinforcing material effective for reinforcing the micro region, and may be simply referred to as “micro-fiber material” hereinafter.

<2> 0.5% by volume to 3.0% by volume of the macro reinforcing steel fiber, 0.5% to 3.0% by volume of the meso reinforcing fiber, and a total content of the micro reinforcing material in the binder. The hydraulic material according to <1>, which is contained in an amount of 1% by mass to 20% by mass.
<3> The hydraulic material according to <1> or <2>, wherein the meso reinforcing fiber includes an organic fiber that melts or reduces volume by 50% or more at a temperature of 180 ° C. or higher.
<4> The hydraulic material according to any one of <1> to <3>, wherein the meso reinforcing fiber includes a metal fiber or carbon fiber having a diameter of 5 μm to 300 μm and a length of 1 mm to 20 mm.
<5> The hydraulic material according to any one of <1> to <4>, wherein the strength of the steel fiber constituting the macro-reinforced steel fiber is in a range of 2000 MPa to 5000 MPa.
<6> The water according to any one of <1> to <5>, wherein a total length of the steel fibers constituting the macro-reinforced steel fibers is 5 mm to 50 mm, and an average diameter of the steel fibers is 50 μm to 600 μm. Hard material.
<7> The hydraulic material according to any one of <1> to <6>, wherein the water / binder ratio is 0.1 or more and 0.3 or less.
<8><1> to <7>, the maximum tensile strength obtained by curing the hydraulic material according to any one of <1> to <7> is 10 N / mm ² or more, and the tensile strength is 1% when deformed A hydraulic material cured body having a proof stress of two-thirds or more of the maximum value of tensile strength and a tensile proof stress at the time of 2% deformation of one-third or more of the maximum value of tensile strength.

The hydraulic material in the present specification is a concept including cement, mortar, and concrete, and typically includes cement, aggregate, hydratable material, and water, and has a water / binder ratio ( Concrete compositions having a mass basis of 0.1 or more and 0.3 or less can be mentioned.
The hardened hydraulic material in the present specification refers to a hardened body obtained by mixing a concrete composition and a cement composition, putting them in a mold, and curing them. In addition, when forming a high intensity | strength hardening body, in addition to normal curing, the steam curing which cures a hardening body in the temperature range of 70 to 100 degreeC for 2 hours to 72 hours, the temperature range of 100 to 400 degreeC It is also a preferred embodiment that one or more kinds of curing selected from high-temperature curing heated for 2 hours to 72 hours and high-temperature high-pressure curing using an autoclave or the like are appropriately combined.

By using a hydraulic material of the present invention, the water / binder ratio is 0.1 or more and 0.3 or less, the compressive strength is in the range of ^{60N / mm 2 ~400N / mm 2} , and the tensile strength and A hydraulic material cured body having excellent toughness can be formed. Such a cured hydraulic material is also useful as a material for forming a structural member such as a building.
The operation of the present invention is not clear, but is considered as follows.
When the hydraulic material hardened body breaks, cracks are first generated at the micro level, which develops to the meso level and the macro level, and is thought to eventually break.
The hydraulic material of the present invention, as a reinforcing material, is a double-end hook-type macro-reinforced steel fiber that is effective for reinforcing cracks in a macroscopic area that can be visually confirmed macroscopically, Meso-reinforcing fibers that are selected from inorganic fibers and organic fibers and that effectively reinforce cracks in the intermediate region between macro and micro, and micro that is effective for reinforcement in the micro region selected from wollastonite and mica Since the reinforcing material includes three kinds of reinforcing materials, when a tensile stress is applied to the cured body formed of the hydraulic material, performance that has not been achieved so far is exhibited. That is, while the cement matrix behaves elastically, the three types of reinforcements cooperate with each other through the adhesion of the matrix and the reinforcements to resist tension, so the elastic range until cracking occurs. The value of tensile stress increases. When the region exceeds the elongation capacity of the matrix, fine cracks start to form from the matrix, but the cross-linked structure formed by micro-reinforcing materials such as wollastonite first suppresses the generation of nano-sized cracks inside the cured body. The stress is transmitted by cross-linking. When the deformation progresses while the stress increases further, it progresses to a medium size crack. The stress due to this size crack was selected from flexible organic fibers and inorganic fibers uniformly dispersed in the cured body. Meso-reinforced fibers that do not have hook portions at both ends are effectively burdened and further development of cracks is suppressed. Furthermore, since the strength reduction of the steel fiber at the time of plastic deformation is suppressed in the macro reinforced steel fiber, a large pulling resistance is obtained, and a high tensile strength is achieved in the cured body. Further, since the macro-reinforced steel fiber has hook portions at both ends and the steel fiber itself has high strength, it resists at the time of pulling out while being accompanied by plastic deformation, so that the toughness is hardly lowered.

  The reinforcing materials in the three regions of macro, meso, and micro are each independent, and specifically have the following effects. That is, the macro-reinforced steel fiber is effective for reinforcing a crack having a width of about 0.05 mm (50 μm) to about 2 mm that can be visually confirmed. The micro-reinforcing material is effective for suppressing the occurrence of cracks having a width of several nanometers to several micrometers generated at the size of cement particles and hydrates and for reinforcing by crosslinking. Further, the meso-reinforced fiber has a plurality of cracks with a width of about 1 μm to 50 μm before progressing to a macro-size crack, or a crack with a width in the micro region generated at the size of cement particles or hydrate level. It is effective for reinforcing the area where the book is generated. Such three kinds of reinforcing materials are uniformly dispersed in the hydraulic material, respectively, and they are combined and combined to produce the excellent effect of the present invention.

In a preferred embodiment of the present invention, at least one type of organic fiber, particularly an organic fiber that evaporates or reduces by heating, is used as the meso-reinforcing fiber. As a result, the toughness can be further improved without lowering the fluidity of the hydraulic material itself, and not only the compressive strength, tensile strength and toughness of the cured hydraulic material can be improved. In addition, the explosion resistance is improved.
In addition, the tensile strength in this specification refers to the maximum value in relation to stress strain.

According to the present invention, in a hydraulic material, water having improved tensile strength and toughness as well as compressive strength, even when the water / binder ratio is reduced for the purpose of improving the compressive strength of the cured body. A hydraulic material capable of forming a hardened material can be provided.
Furthermore, according to this invention, the hydraulic material hardening body which is excellent in both the compressive strength and the tensile strength which uses the hydraulic material of the said invention is provided.

It is a schematic front view which shows an example of the both-ends hook type steel fiber used for this invention.

Hereinafter, the hydraulic material of the present invention and the cured hydraulic material obtained from the hydraulic material will be described in detail.
[Hydraulic material]
The hydraulic material of the present invention includes (A) a binding material, (B) an aggregate, (C-1) a first hook that is bent so as to have an angle with the straight portion from both ends of the straight portion and the straight portion. And (C-2) an organic fiber and an inorganic fiber having a second hook part that is bent in a direction away from each other and a second hook part that is parallel to the straight part. 1 or more types of meso reinforcing fibers, and (C-3) a micro reinforcing material selected from wollastonite and mica. Hereinafter, these (C-1) macro reinforced steel fibers, (C-2) meso reinforced fibers, and (C-3) micro reinforcing materials may be collectively referred to as “reinforcing materials (C)”.
First, various reinforcing materials (C) contained in the hydraulic material of the present invention will be described.
(C-1) Macro Reinforced Steel Fibers for Both End Hooks FIG. 1 is a front view showing an embodiment of reinforcing both end hook type steel fibers 10 that can be used for the hydraulic material of the present invention.
The hook-type steel fiber 10 at both ends is a steel fiber, and includes a straight portion 12, first hook portions 14 </ b> A and 14 </ b> B bent at an angle with the straight portion 12, and the first hook portion 14 </ b> A, 14B is a double-end hook-type steel fiber having second hook portions 16A and 16B that are bent in a direction away from each other and parallel to the linear portion, and the shape is not particularly limited as long as both ends have hook shapes. .

The steel fiber constituting the double-end hook-type steel fiber 10 has a total length of 5 to 50 mm, and the average diameter (φ) of the steel fiber constituting the double-end hook-type steel fiber is 50 μm to 600 μm. It is preferable from the point that a strong reinforcing effect is obtained.
In addition, the tensile strength of the steel fiber (element wire) is preferably 2000 MPa or more and 5000 MPa or less. The higher the strength of the strand is, the more effective as the reinforcing fiber, but the upper limit is set to 5000 MPa in consideration of workability and the like. From such a viewpoint, the tensile strength of the strand is 3000 MPa or more. It is more preferable. The tensile strength of the steel fibers that make up the hook-type steel fibers at both ends is in accordance with the JSCE-E101-2007 appendix (normative) “Tensile Strength Test Method for Steel Fibers” of the Japan Society of Civil Engineers. It is evaluated.
In the loading test, a universal testing machine model 55R1125 manufactured by Instron was used, and the displacement speed was tested by pulling at a crosshead speed of 0.2 mm / min. The average value of the five test results was taken as the test value. In this standard, it was fixed with a flat plate chuck. Steel fibers with a diameter of about 0.2 mm or less were often broken near the chuck when tested using a flat plate chuck. Use an air capstan type thread clamp (manufactured by Shimadzu Corporation). The fiber fixing portion was provided at a position half a round around the cylindrical portion with respect to the pulling direction, and the test was conducted so as not to break at the grip portion.
In order to achieve such a tensile strength, for example, JIS G 7305 "Spring Steel Wire-Part 2: Cold-drawn Carbon Steel is used as the material of the steel fiber (element wire) constituting the hook-type steel fiber at both ends. JIS G 7306 "Spring Steel Wire-Part 3: Oil Temper Wire (ISO Specification)", JIS G 3522 "Piano Wire", JIS G 3521 "Hard Steel Wire", etc. Is preferred.

Here, the total length (l _a ) of the hook-type steel fibers at both ends refers to the distance from the end portion of one second hook portion 16A to the end portion of the other second hook portion 16B, and is 6 mm to 50 mm. More preferably, it is 15 mm-40 mm.
By setting the total length within the above range, resistance to tensile stress is further improved, and generation of cracks when subjected to tensile stress is more effectively suppressed.

Hereinafter, although the other preferable aspect of the both-ends hook type steel fiber 10 used for this invention is given, this is an example and this invention is not restrict | limited to these description.
The length (l ₁ ) of the second hook portions 16A, 16B parallel to the straight portion 12 of the hook-type steel fiber 10 at both ends is preferably 1 mm or more, and when the diameter (φ) is 50 μm or more, it is 2.5 mm or more. Is preferred. If the length is too short, the resistance to tensile stress decreases. Although there is no restriction | limiting in particular in the upper limit of length, From a viewpoint of workability | operativity at the time of mixing with a hydraulic material, it is preferable that it is 5 mm or less.
As shown in FIG. 1, the length (l ₁ ) of the second hook portions 16A and 16B is the distance from the bent position of the first hook portions 14A and 14B to the end portions of the second hook portions 16A and 16B. Point to.
The ratio (l ₁ / φ) between the diameter (φ) of the steel fiber and the length (l ₁ ) of the second hook portions 16A and 16B is preferably 5 or more and 25 or less. For example, the diameter (φ) is In the case of 0.30 mm or more, it is preferably 6.5 or more and 15 or less.

Further, the bending height (h) of the first hook portions 14A and 14B, which is the distance between the straight portion 12 and the second hook portions 16A and 16B, is preferably 0.3 mm or more, and the diameter (φ) of the steel fiber. When is 0.30 mm or more, it is preferably 0.8 mm or more. Although there is no restriction | limiting in particular in the upper limit of height (h), From a viewpoint of making uniform mixing easy when mixing with a hydraulic material, it is preferable that it is 3 mm or less. As shown in FIG. 1, the bending height h indicates the distance between the center line of the steel fiber in the second hook portions 16 </ b> A and 16 </ b> B and the center line of the steel fiber in the straight portion 12.
Here, the ratio (h / φ) between the diameter (φ) of the steel fiber and the bending height (h) of the first bent portions 14A, 14B is preferably 2 or more and 10 or less, and is 3 or more and 6 or less. More preferably.
In another preferred embodiment, the radius of curvature of the R portion formed by the inner side surfaces of the bent portions of the first hook portions 14A and 14B and the second hook portions 16A and 16B is r1, and the linear portion 12 and the An aspect in which r1 / φ is 3 or more and 10 or less, where r2 is the radius of curvature of the R portion formed by the inner surfaces of the bent portions of the first hook portions 14A and 14B, and φ is the diameter of the steel fiber, or , R2 / r1 is 1.5 or more and 10 or less.

Moreover, it is preferable that the relationship between the length (l ₂ ) of the straight portion 12 of the hook-type steel fiber 10 at both ends and the length (l ₁ ) of the second hook portions 16A and 16B satisfies the following formula.
(Formula) 6 × l ₁ <l ₂
In the balance of both lengths, the length (l ₁ ) of the second hook parts 16A, 16B has the length of the above ratio with respect to the length (l ₂ ) of the straight line part 12, so that the shape of the hook Works more effectively, the pull-out resistance in the hydraulic material is further improved, and the resistance to tensile stress of the cured hydraulic material is further improved.

In the production of the double-end hook type steel fiber according to the present invention, the first hook portion and the second hook portion can be formed into the preferred shape by adjusting a coiling machine for precision spring processing. When producing in large quantities, you may manufacture with the gear type shaping | molding apparatus etc. which are shown by Unexamined-Japanese-Patent No. 5-337727.
The both-end hook type steel fiber surface may be subjected to chemical or physical surface treatment such as primer treatment or surface roughening treatment for the purpose of improving adhesion to a hydraulic material described later.

  The content of the hook-type steel fibers at both ends with respect to the hydraulic material is preferably in the range of 0.5% by volume to 3.0% by volume, and more preferably in the range of 1.0% by volume to 3.0% by volume. . When the content is in the above range, the tensile strength and toughness of the cured body are further improved.

(C-2) One or more types of meso reinforcing fibers selected from organic fibers and inorganic fibers The meso reinforcing fibers used in the present invention are smaller in size than the (C-1) both-end hook type steel fibers, A fiber that does not have a hook is selected.
As meso-reinforcing fibers, it is possible to select thin and flexible fibers that can be uniformly dispersed without greatly reducing fluidity even when added to an uncured hydraulic material composition such as fresh concrete. preferable.
The kind of meso reinforcing fiber may be an inorganic fiber such as steel fiber or carbon fiber, or may be an organic fiber selected from vinylon fiber, polyethylene fiber, polyamide fiber, polypropylene fiber, polylactic acid fiber, and the like.
The inorganic fiber preferably has a length in the range of 1 mm to 20 mm, and more preferably in the range of 3 mm to 15 mm. The average fiber diameter (fiber diameter φ) is preferably in the range of 5 μm to 300 μm, and more preferably in the range of 5 μm to 150 μm.
In view of the fact that the size of the inorganic fiber is within the above range, a sufficient reinforcing effect by restraining the hydraulic material is obtained, the fluidity of the hydraulic material composition before curing is appropriately maintained, and the workability is improved. To preferred.

The inorganic fibers may be monofilaments or converged strands.
The shape of the inorganic fiber does not necessarily have to be a cylindrical shape, and may be a spindle shape or a needle shape as long as the length and the maximum diameter are within the above-described range, may be a modified cross-section fiber, have an appropriate aspect ratio, and have a surface area. Large fibers are preferred from the standpoint of adhesion to hydraulic materials.
Examples of the inorganic fibers include metal fibers typified by steel fibers and stainless fibers, carbon fibers, and glass fibers. Metal fibers are preferred from the standpoint of effects and availability, but non-metallic inorganic fibers such as carbon fibers, basalt fibers, and glass fibers, which are less susceptible to strength reduction in high temperature environments and have excellent adhesion to the matrix, are also present. In the invention, it is preferably used.
Depending on the use mode of the cured body, carbon nanotubes that are smaller than the preferred size but have excellent adhesion to the matrix can be suitably used as the meso reinforcing fiber in the present invention. Even in such a small reinforcing fiber, the size is not always constant, so that the function and effect as a meso reinforcing fiber is also manifested. It is also expected to have a reinforcing effect against cracks of a smaller size than a crack that can be effectively suppressed by meso-reinforcing fibers where the material acts.

  The organic fiber preferably has a fiber diameter in the range of 5 μm to 200 μm, and more preferably in the range of 5 μm to 50 μm. When the fiber diameter is in the above range, a sufficient strength improvement effect can be obtained. In addition, as described in detail below, the cured hydraulic material can be made to have explosion resistance by using organic fibers whose volume is reduced by heating, but also from the viewpoint of ensuring explosion resistance, the fiber diameter Is preferably in the above range.

Further, the length of the organic fiber is preferably in the range of 1 mm to 20 mm, and more preferably in the range of 2 mm to 10 mm. In this range, the uniform dispersibility in the hydraulic material becomes better, and if desired, a good explosion resistance can be imparted.
These organic fibers can be used as monofilaments or strand fibers as long as they can be uniformly dispersed without agglomerating in the concrete. Further, even in the case of a monofilament, it may not necessarily be a columnar shape, and may be a hollow fiber, a modified cross-section fiber, or a fiber having pores or fine branches on the surface as long as fluidity is not impaired.
Examples of the organic fiber include fibers made of an organic resin such as vinylon fiber, polyethylene fiber, polyamide fiber, polypropylene fiber, and polylactic acid fiber, and may be appropriately selected in consideration of durability and strength.
In addition, although the hardened | cured material of high compressive strength is easy to produce an explosion when exposed to high temperature, for example, as an organic fiber, it melts at a temperature of 180 ° C. or higher, or the mass is reduced by 50% or more. By using the organic fiber, the volume of the organic fiber is quickly reduced during heating and a void is formed, so that explosion resistance can be imparted to the cured body.
Here, when the organic fiber is melted when heated to 180 ° C. or higher, the fiber is liquefied and vaporized exceeding the melting point when heated to 180 ° C. In addition, confirming that the mass of the organic fiber has decreased by 50% or more is that the mass of the sample weighed while increasing the temperature of a sample of several mg at a rate of temperature increase of about 5 ° C./min in a nitrogen gas environment. It can measure by a balance and can be performed by comparing with the mass before a heating when it becomes 180 degreeC or more.

Specific examples of organic fibers that can impart explosion resistance include organic fibers such as polypropylene fibers, polyvinyl alcohol fibers, polyvinylidene fibers, and polylactic acid fibers. By using these organic fibers, the organic fibers are melted or reduced in volume at a high temperature, and effective voids are quickly formed in the cured body, forming a path for the generated water vapor and effectively preventing explosion.
A commercial item can also be used as such an organic fiber, for example, Daiwabo polypro by Daiwabo Polytech Co., etc. are mentioned.

The hydraulic material of the present invention may contain only one type of meso reinforcing fiber, or two or more types may be used in combination. Also, one or more inorganic fibers may be selected and one or more organic fibers may be selected and used in combination.
The content of meso reinforcing fibers in the hydraulic material is preferably 0.5% by volume to 3.0% by volume, and more preferably 1.0% by volume to 3.0% by volume.
Here, in order to impart explosion resistance to the cured hydraulic material, when using one or more organic wires as the reinforcing fiber, the content of the organic fiber is 0.1% by volume to 1.0% by volume. A range is preferable.
With the above content, an effective reinforcing effect can be obtained without impairing the fluidity of the hydraulic material, and in particular, when an organic fiber is used, a cured body having excellent explosion resistance can be obtained.

(C-3) Microreinforcing material selected from wollastonite and mica The hydraulic material of the present invention contains a microreinforcing material selected from wollastonite and mica.
Wollastonite (CaSiO ₃ ) is an acicular crystal mineral having an aspect ratio representing a ratio of length to small diameter (short diameter) of about 3 or more. As a microreinforcing material in the present invention, the aspect ratio is 5 The above is preferable.
Moreover, it is preferable that a volume average diameter is 5 micrometers or more and 500 micrometers or less, and it is more preferable that they are 10 micrometers-200 micrometers.
Wollastonite is also available as a commercial product. For example, NYAD G (trade name: average length 300 μm, diameter 20 μm, aspect ratio: 15) manufactured by NYCO, Wollastonite NYCO 1250 (trade name: Examples include an average length of 8 μm and an aspect ratio of 3).
The aspect ratio of wollastonite is obtained by dispersing sampled wollastonite on a preparation and observing the image with a microscope with a magnification of 30 times or more, and dividing the length in the long side direction by the length in the short side direction. Ask. In this method, since the number of measurements is limited, the particle size is often obtained by using a laser diffraction / scattering particle size distribution analyzer or a sedimentation method. The average length is often obtained by multiplying the volume average particle diameter by the aspect ratio obtained from the image. In this specification, the value measured by this method is used.
Moreover, what is necessary is just to use what has a catalog value in the said range when using a commercial item.

Another example of the micro reinforcing material is mica flakes. Mica is also referred to as muscovite (mascobite), and some of the mica exists in a hydrated silicate state selected from aluminum and potassium. More specifically, it is mica having a maximum dimension of 0.1 mm to 2 mm, and the maximum dimension is more preferably 0.5 mm to 2 mm.
Mica is also available as a commercial product, and examples thereof include B-82 (32 mesh, average particle size 180 μm), C-93 (16 mesh, maximum size of about 1 mm) manufactured by Yamaguchi Mica.
The maximum size of mica is measured by the mesh size of the sieve (number of meshes per inch) or the volume average diameter by a laser diffraction / scattering particle size distribution meter. In this specification, the value measured by the former method is used. Yes.

The hydraulic material of the present invention may contain only one type of wollastonite and mica as a micro reinforcing material, or two or more types may be used in combination. Wollastonite and mica may be used in combination.
The content of the micro reinforcing material in the hydraulic material is preferably 1% by mass to 20% by mass, and more preferably 5% by mass to 20% by mass with respect to the total content of the binder.
When the content ratio is in the above range, it is more preferable because the effect of reinforcing at the cement hydrate level can be obtained while suppressing a decrease in fluidity caused by mixing the micro reinforcing material. Further, it is preferable to reduce the mass of the aggregate in accordance with the amount of the micro reinforcing material mixed from the viewpoint of making the hydraulic material have a better level of mobility.

[Hydraulic material]
The hydraulic material of the present invention is not particularly limited as long as it has hydraulic properties, and includes cement, mortar, concrete, etc. It is done. Among them, when applied to a concrete composition that requires high strength and toughness, the effect of adding double-end hook-type macro-reinforced steel fibers, meso-reinforced fibers and micro-reinforcing materials is high. This is because, when the strength of the cured body is a certain level or more, the anti-pulling effect of the hook-type steel fibers at both ends, the effect of preventing the occurrence of fine cracks of the meso-reinforcing fiber, and the micro-reinforcing material are more favorably exhibited. it is conceivable that.
The hydraulic material of the present invention includes cement, aggregate, water, and three kinds of reinforcing materials (C) according to the present invention, and the content thereof is preferably a hook at both ends as described above. 0.5% to 3.0% by volume of steel mold fiber, 0.5% to 3.0% by volume of the meso reinforcing fiber, and 1% by mass to 20% of the micro reinforcing material with respect to the total content of the binder. It is the range of mass%.

Among the hydraulic materials, a hydraulic material capable of forming a high-strength cured body having a water / binder ratio of 0.1 to 0.3 in terms of mass ratio is preferable. Hereinafter, unless otherwise specified, the water / binder ratio is expressed on a mass basis.
An example of the hydraulic material includes cement, aggregate, silica fume, water, and the three reinforcing agents (C) according to the present invention in a predetermined content, and the water / binder ratio is 0 by mass. Preferably, the cement composition is 1 or more and 0.3 or less.

(Each component of hydraulic material)
Hereinafter, materials used for the cured hydraulic material of the present invention will be described.
(Water / Binder ratio)
The cement composition (which may be a concrete composition further including coarse aggregate as an aggregate) used in the production of the hardened cement of the present invention has a water / binder ratio of about 0.5 on a mass basis. However, from the viewpoint that a high-strength cured body can be formed, the water / binder ratio is preferably 0.1 or more and 0.3 or less.
In addition, it contains at least other binders such as silica fume, including water and cement. Depending on the purpose, aggregates such as fine aggregates and coarse aggregates, water reducing agents, etc. Containing.
In the present invention, the binder is a hydration reaction in cement, which is a main component of a hardened cement body, and a concrete composition such as silica fume, slag, fly ash or the like generally used with cement, and is involved in the hardening of the hardened cement body. It is used in the meaning including solid content materials such as fine powder. Note that aggregates and surfactants added to improve fluidization are not included in the binder in the present invention.

(cement)
There is no restriction | limiting in particular in the cement used for manufacture of the cement hardening body of this invention, According to the objective, it can select suitably from various cements. As the cement, known cements such as ordinary Portland cement, moderately hot Portland cement, low heat Portland cement, and early-strength Portland cement can be suitably used, but low heat Portland cement is preferable.
Portland cement containing silica fume in advance may be used. Portland cement containing silica fume is also available as a commercial product, for example, trade name: silica fume cement super, silica fume cement, manufactured by Taiheiyo Cement Co., Ltd .: silica fume premix cement, and the like.

(Silica fume)
The cement composition used for producing the hardened cement body of the present invention may contain silica fume.
The silica fume used preferably can be used in either powder or granular form. As the silica fume, silica fume (average particle size: 0.1 μm to 0.2 μm) by-produced during the production of ferrosilicon, electrofused zirconia, and metal silicon is preferable.
In addition, the particle diameter of the silica fume in this specification uses the value calculated by calculating the specific surface area by the BET method and assuming that the particle density and the particles are spherical from the specific surface area.

  As content of a silica fume, it is preferable that it is 5 mass%-35 mass% in all the binders in a cement composition, and it is more preferable that it is 10 mass%-30 mass%. In order to contain 5% by mass to 35% by mass of silica fume in the total binder, 5% by mass to 35% by mass of cement as the binder may be replaced with silica fume. When the content of silica fume is within the above range, the fluidity improving effect and the strength improving effect are sufficiently exhibited.

(Other binders)
When producing the hardened cement body of the present invention, as long as the effects of the present invention are not impaired, other binders are appropriately selected according to the intended use of the cement composition to be prepared and used in an appropriate amount. May be.
Examples of other binders include silica fine powder obtained by finely pulverizing crystalline silica, slag such as blast furnace slag fine powder, limestone fine powder, fly ash and the like.

(aggregate)
The cement composition for producing the hardened cement body of the present invention contains an aggregate. The aggregate is preferably a fine aggregate, and may be a concrete composition containing a fine aggregate and a coarse aggregate.
(Fine aggregate)
For fine aggregates, high-quality and solid natural sand, crushed sand and processed sand are used. The type and content of fine aggregates can be selected as appropriate according to the strength of the target cement hardened body, but when crushed sand or processed sand is used, the one with treated corners or one with adjusted particle size Etc. are effective.
(Coarse aggregate)
In the case of using a coarse aggregate in addition to the fine aggregate as the aggregate, a good quality and solid coarse aggregate may be used. The maximum size of the coarse aggregate requires a particle size (maximum particle size) of 20 mm or less, and preferably the maximum size is 15 mm or less. About a rock kind, what is necessary is just to select suitably according to the target intensity | strength from general things, such as a hard sandstone, andesite, and rhyolite. By using a coarse aggregate for the cement composition forming the cement hardened body, a concrete composition is obtained, and the strength of the obtained hardened body is further improved. In addition, the term “cement composition” in the present specification is used to include a “concrete composition” further including a coarse aggregate as an aggregate.

(Other ingredients)
Depending on the purpose, the cement composition used for the cured hydraulic material of the present invention may further contain other components usually used in concrete compositions such as a water reducing agent and a retarder.
The hardened cement body of the present invention can be obtained by curing a cement composition appropriately containing each component as described above and performing the following specific curing.

[Hardened hydraulic material]
The hydraulic material cured body of the present invention is a hydraulic material containing (C-1) double-end hook-type steel fiber, (C-2) meso reinforcing fiber, and (C-3) micro reinforcing material according to the present invention. Obtained by curing.
Since the hydraulic material cured body of the present invention contains the three kinds of reinforcing materials (C), the obtained cured body has a compressive strength of 60 N / mm ² or more and a maximum tensile strength, That is, it becomes a hydraulic material cured body having excellent strength and toughness that the maximum value of tensile stress in terms of stress-strain is 10 N / mm ² or more. The compressive strength of the cured body is more preferably 120 N / mm ² or more, and the tensile strength is 12 N / mm ² or more.
Further, the tensile strength at 1% deformation at the time of tensile strength measurement is 2/3 or more of the maximum value of the tensile strength, and the tensile strength at 2% deformation of the tensile strength is 3 minutes of the maximum value of tensile strength. It is preferable that it is 1 or more.
The compressive strength is adjusted by a method of adjusting the composition of the hydraulic material, for example, adjusting the water / binder ratio, or using an appropriate curing accelerator or water reducing agent. The tensile strength and the tensile strength at the time of 1% deformation and 2% deformation are adjusted by adjusting the respective contents of the three types of reinforcing materials (C) according to the present invention.
Specifically, for example, in the cement composition in which the water / binder ratio is in the range of 0.1 to 0.3 by mass, It is preferable to contain 1% by mass to 20% by mass of meso reinforcing fibers and 0.5% to 3.0% by mass of microfiber reinforcing material selected from wollastonite and mica. .

(Method for producing a cured hydraulic material)
In order to produce the cured hydraulic material of the present invention, cement, aggregate, water, (C-3) micro-reinforcing material, and various additives used in combination as desired are mixed and made uniform (C -1) Adding a double-end hook-type macro-reinforced steel fiber and (C-2) meso-reinforced fiber, mixing them further, then putting them into a mold and curing them to form a cement molded body Good. The formed cement molded body is cured as necessary to obtain a cured hydraulic material having sufficient strength.
Mixing can be performed by a conventional method. First, a slurry of a hydraulic material is prepared. That is, cement, aggregate, water, (C-3) micro-reinforcing material is added to 1% to 20% by mass of the total content of the binder, and silica fume and other additives added as desired are added to the mixer. Then, a slurry is prepared by mixing. In addition, first, aggregates may be mixed, then cement and additives may be added and mixed, and then water may be added and mixed to prepare a slurry. A slurry may be prepared by kneading mass% and water to prepare a slurry, and then adding and mixing the remaining binder.
After preparation of the slurry, (C-1) 0.5% by volume to 3.0% by volume of the double-end hook-type macro-reinforced steel fiber, and (C-2) 0.5% by volume to 3.0% of the meso-reinforced fiber. In the range of%, an amount corresponding to the purpose of each hydraulic material is added and mixed to obtain a cement composition.
The prepared slurry is put into a mold and cured to form a cement molded body. Since the hydraulic material according to the present invention has the above configuration, the water / binder ratio is useful for forming a high-strength cured body having a mass ratio of 0.1 to 0.3. After the slurry-like cement composition is put into the mold, a process such as defoaming may be further performed according to a conventional method.
The cement composition thrown into the mold is cured with self-heating to form a cement molded body. The cured cement molded body thus obtained is cured to improve the strength.

The applicable curing method is not particularly limited, and a general curing process applied when forming a cement or concrete hardened body may be performed.
There is no particular limitation on the curing process, and any curing may be performed, for example, standard curing performed in water, wet sand, or saturated steam maintained at a temperature of 20 ± 3 ° C., or water performed in water. Curing, high temperature, for example, a method in which a cement molded body is steam-cured in a temperature range of 70 ° C. to 100 ° C. for 2 hours to 72 hours, and is heated at a heating temperature of 100 ° C. to 400 ° C. for 2 hours to 72 hours. And autoclave curing under high temperature and high pressure in a sealed container.
The curing process may be performed at any timing as long as the cement molded body is cured. For example, it may be performed immediately after the cement molded body is cured, or may be performed after the cement molded body is cured to some extent. When the curing process is performed after a lapse of time, the curing process may be performed after the self-heated molded body has cooled to room temperature, or a plurality of molded bodies may be prepared and then the curing process may be performed collectively. .

Steam curing is performed by a conventional method. For example, steam produced by a boiler can be introduced into a curing tank through an introduction pipe, a temperature sensor is installed in the tank, and the temperature in the tank is set. Steam curing performed by opening and closing the steam supply valve so as to become a temperature history is the most common, but as another steam curing method, after taking measures that the molded body does not dry extremely, for example, Examples of the method include heating by attaching a sheet heating element or the like that generates heat by energization to the surface of the molded body, and steam curing may be performed by such a method.
The cured hydraulic material containing the three types of reinforcing materials (C) of the present invention exhibits a more stable and practically sufficient strength and toughness through the curing process performed as desired, and is suitable for various structural materials. Used for.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not restrict | limited to these description.
In the following examples, examples in which a cement composition is used as a hydraulic material will be given.
(Examples 1-7, Comparative Examples 1-6)
[Cement composition]
(Materials used)
Cement: Silica fume premix cement (trade name: manufactured by Mitsubishi Ube, density 3.01 g / cm ³ , abbreviation: SFCS)
Water: Tap water Fine aggregate: Mikawa quartz sand R6 (grain size D50 212 μm, density 2.6 g / cm ³ )
Coarse aggregate: Otsuki No. 6 crushed stone (maximum particle size 13 mm, surface dry density 2.58 g / cm ³ )
Admixture: SSP-104: (Brand name: Takemoto Yushi Co., Ltd., solid content 30%)
Antifoaming agent: AFK-2 (trade name: Takemoto Yushi Co., Ltd. Density: 1 g / cm ³ )

Reinforcing material (C):
(C-1) Both End Hook Type Macro Reinforced Steel Fiber The both end hook type macro reinforced steel fiber will be described later.

(C-2) Meso reinforcing fiber (a) Steel fiber (diameter 0.16 length 6 mm) (abbreviation: OL6)
(B) Steel fiber (diameter 0.16 length 13 mm) (abbreviation: OL13)
(C) Polypropylene fiber (manufactured by Daiwabo, 2.2 dex, length 4 mm: used after correcting moisture content) (abbreviation: PP)

(C-3) Micro-reinforcing material (d) Mica CS-060DC (average particle size 200 μm, bulk specific gravity 0.29)
(E) Mica C-93 (maximum particle size: 100 μm, bulk specific gravity 0.22)
(F) Wollastonite KSP01 (average particle diameter: 19.8 μm, aspect ratio 3 to 15, bulk specific gravity 0.45)
Table 1 below shows the composition of the cement composition applied to the production of the cured hydraulic material of the present invention.
* In Table 1 below, the moisture contained in the admixture was a part of water, and the solid content was divided by the unit volume.
* The addition ratio (volume%) of the meso reinforcing fiber and the double-end hook-type macro reinforcing steel fiber was set to be an external division of the capacity of the matrix portion of the hydraulic material. The addition amounts of the macro reinforced steel fibers and meso reinforcing fibers described in Table 3 and below are also the same.

[(C-1) Production of hook-type macro-reinforced steel fibers at both ends]
Steel fibers having the shapes shown in Table 2 below were molded by adjusting a coiling machine for precision spring machining.
[Measurement of macro-reinforced steel fiber shape]
The fiber diameter (φ) of the steel fiber is a value obtained by measuring the shape of a total of 20 positions at both ends of the steel fiber arbitrarily extracted with a microscope (manufactured by Keyence Corporation: Digital HF microscope VH-8000). In addition, the shape of the steel fiber such as the total length, the length of the first hook part, the radius of curvature, the bending angle, and the bending height is drawn using the microscope shape measurement function and the center line of the fiber is drawn on the obtained image. The original measured value is used. Specifically, for the straight portion of the steel fiber, the center point in the diametric direction of the fiber is obtained in the vicinity of the start point and end point of the straight portion, and the center line is drawn by connecting the two points, and the bent portion has three points in the diametric direction. The center point described above was obtained, a circle passing through this was obtained, and the radius of the circle was defined as the radius of curvature. Here, l ₁ is the distance from the tip to the center of the first bend. l ₂ is the distance from the center of the second bent portion from the tip to the symmetrical point of the opposite end. Table 2 shows average values of 10 measurement results.

[Measurement of tensile strength of wire forming macro-reinforced steel fiber]
Moreover, the tensile strength of the strand which forms a both ends hook type | mold steel fiber was measured with the following method.
Displacement using the universal testing machine model 55R1125 manufactured by Instron Co., Ltd. The speed was tested by pulling at a crosshead speed of 0.2 mm / min. Fibers with flat chuck for fixing, of the total length 30mm fibers, gripping the both ends 12.5mm chuck was measured intensity at the points corresponding to the central portion 5mm straight portion l ₂ of the steel fibers. Data that caused slipping at the gripping part or early breakage at the gripping part was excluded, and one new test was added, and the average value of the five test results was taken as the strength. The average values were 2911 MPa for A and 3110 MPa for B.

(1. Preparation of hydraulic material)
Regarding the cement composition shown in Table 1, first, cement, (C-3) micro-reinforcement material and fine aggregate, half amounts of each and other additives were put into an omnimixer, kneaded for 30 seconds, and mixed with water. The agent was added and kneaded at a low speed (speed: 150 rpm) for 60 seconds, and the remaining amount of cement, fine aggregate and (C-3) micro-reinforcing material were added, kneaded for 240 seconds, then scraped off and further stirred for 60 The mixture was further stirred and mixed at a medium speed (speed: 300 rpm) for 2 seconds.
Then, (C-1) both ends hook type macro reinforced steel fiber and (C-2) meso reinforcing fiber are added, and the amount of kneading amount is 5L, omnimixer (OM-10E manufactured by Chiyoda Machinery Co., Ltd.) 10 L) and further kneaded for 240 seconds at a speed of 300 rpm.
In this way, the hydraulic material of the example was prepared.
In addition, content (mass%) of the micro reinforcement material described in following Table 3 represents the mass ratio with respect to the total amount of the binder contained in a hydraulic material. When micro-reinforcing material was mixed, aggregates with the same mass were reduced. In addition, the contents of the double-end hook-type macro-reinforced steel fiber and meso-reinforced fiber indicate the volume ratio (volume%) of the cured body to the hydraulic material when the volume of these fibers is negligible. It is a thing.

(2. Molding of hardened hydraulic material)
The hydraulic material of Example 1 (steel fiber mixed cement composition) was put into a dumbbell-shaped test body for tensile testing. For compressive strength, it was put into a steel mold having a diameter of 5 cm and a height of 10 cm.
For the tensile test, a cured body having a fixed holding portion at the top and bottom of the test body and having a tensile test section having a thickness of 3 cm, a width of 3 cm, and a length of 8 cm at the center of the test body was prepared. The fixed holding part is tapered with a gradient of 15/40 from the part of thickness 3cm, width 6cm length 8.5cm and the tensile test part in the center, so that there is no sudden change in cross section It was used.
This is left to stand for 5 to 7 days to be naturally cured, taken out from the mold, heated at a rate of temperature increase of 15 ° C./hour, maintained at a maximum temperature of 90 ° C. for 24 hours, and cooled at 15 ° C./hour to form a molded product. Got. Then, it stored in the room | chamber interior of 20 degreeC60RH% until test material age.

(3. Compressive strength test of hardened hydraulic material)
On the 14th day of age, the compressive strength of the obtained cured hydraulic material (cured cement) was measured according to JIS A 1108 (2006).
(4. Tensile strength test of hardened hydraulic material)
On the 14th day of age, the dumbbell-shaped specimen was fixed with a jig, and the tensile load was measured with a high-precision universal testing device (Autograph AG-250kN: manufactured by Shimadzu Corporation). The tensile load was obtained by dividing the tensile load by the cross-sectional area (30 mm × 30 mm), and the maximum value was taken as the tensile strength. The displacement meter is attached via a jig so that the displacement at the position of the tensile test part 80 mm in the center of the test body can be measured, and the tensile strain is obtained by dividing the displacement during the test by the distance between the gauge points of 80 mm. It was.
Details of the evaluation items in Table 3 are as follows.
“Tensile strength” is the maximum value (Ft) of the measured values of the tensile strength.
“Tensile strain” represents the tensile strain when the maximum value (Ft) in the tensile strength is obtained.
“Yield strength at 1% tensile strain” indicates the ratio of _1% yield strength at 1% tensile strain to the maximum tensile strength (Ft) for both absolute values. A case where this value is 2/3 or more of Ft is ranked as A rank, and a case where it is less than 2/3 is regarded as data having practical problems.

“Yield strength when tensile strain is 2%” indicates the ratio of yield strength Ft _2% when tensile strain is 2% to the maximum tensile strength value (Ft) for both absolute values. The case where this value was 1/3 or more of Ft was ranked as A rank, and the case where it was less than 1/3 was regarded as B rank as practically problematic data.

From the above results, the hydraulic material of the present invention not only has high compressive strength, flexural strength, and tensile strength, but also the decrease in yield strength in the process of tensile strain in the tensile test is extremely small compared to the comparative example, It can be seen that this is a highly tough material with excellent elongation performance.
On the other hand, not only the mechanical performance but also the cured hydraulic material obtained in Example 6 was evaluated by the following test.

(Fire resistance test)
A fire resistance test was conducted on Comparative Example 6 which differs from Example 5 and Example 6 only in that polypropylene fibers which are meso reinforcing fibers were not mixed.
The fire resistance test was carried out by using a cylindrical specimen having a deformed reinforcing bar having a diameter of 13 mm at the center in the direction perpendicular to the diameter as a cylindrical specimen having a diameter of 15 cm and a height of 30 cm as a cured body of the hydraulic material. After placing the test body, it was allowed to stand indoors, and after a predetermined age (26 weeks) had elapsed, a heating test was performed. At the time of the test, the dry mass was measured by a test method according to JASS 5N T-602, and the water content during the test was determined.
In the test, the test body was installed in the center of the heating furnace for the fire resistance test, and the standard heating temperature curve T = 345 log (8t + 1) +20 (t: time (min)) defined in ISO834 (former Ministry of Construction Notification No. 2999) Then, heating was continued for 60 minutes to confirm the state of destruction.
The weight of the specimen before heating and the weight after heating for a predetermined time were measured, and the degree of explosion was evaluated by the weight reduction rate due to heating. That is, concrete that is easy to explode can be said to have a large weight reduction rate before and after heating because the concrete is scattered and lost from the surface of the specimen due to the explosion.

The weight reduction rate is expressed by the following formula.
Specimen weight reduction rate (%) =
[[Weight before heating (g) −Weight after heating (g)] / Weight before heating (g)]
Table 4 below shows the results of the fire resistance test. Two specimens were tested for one type, and the average value of the weight reduction rates of the two specimens was taken as the test result. It should be noted that, since moisture is dissipated during heating, even in a specimen that does not explode at all, the weight reduction rate is about 6% by mass to 8% by mass although the value varies depending on the adjusted composition. At the same time as the weight reduction rate, the explosion depth was measured with a caliper every 45 ° from the center of the specimen, at a position 25 mm from the upper end, and downward 50 mm from there. Since the original specimen surface is not known when it is blasted, place a transparent cylinder with an outer diameter of 200 mm and measure the depth in the direction perpendicular to it to measure the blast depth at each position. Was the average explosion depth. In the case where no explosion occurred from the appearance, the explosion depth was zero.
As a result, the weight loss rate and the average explosion depth are as shown in Table 4, and it was confirmed that the cured product of Example 5 had excellent explosion resistance.

10 Both-end hook type steel fiber 12 Straight line part 14A, 14B First hook part 16A, 16B Second hook part

Claims (8)

  The binding material, the aggregate, the straight portion, and the first hook portion bent at an angle with the straight portion from both ends of the straight portion and the end portion of the first hook portion are bent in a direction away from each other. A macro reinforcing steel fiber having a second hook portion parallel to the straight portion, one or more meso reinforcing fibers selected from organic fibers and inorganic fibers, and a micro reinforcing material selected from wollastonite and mica Hydraulic material.   0.5% to 3.0% by volume of the macro reinforcing steel fiber, 0.5% to 3.0% by volume of the meso reinforcing fiber, and 1% of the micro reinforcing material with respect to the total content of the binder. The hydraulic material according to claim 1, wherein the hydraulic material is contained in an amount of from 20 to 20% by mass.   The hydraulic material according to claim 1 or 2, wherein the meso reinforcing fiber includes an organic fiber that melts or reduces volume by 50% or more at a temperature of 180 ° C or higher.   The hydraulic material according to any one of claims 1 to 3, wherein the meso reinforcing fibers include metal fibers or carbon fibers having a diameter of 5 µm to 300 µm and a length of 1 mm to 20 mm.   The hydraulic material according to any one of claims 1 to 4, wherein the strength of the steel fibers constituting the macro-reinforced steel fibers is in a range of 2000 MPa to 5000 MPa.   The hydraulic material according to any one of claims 1 to 5, wherein a total length of steel fibers constituting the macro-reinforced steel fibers is 5 mm to 50 mm, and an average diameter of the steel fibers is 50 µm to 600 µm.   The hydraulic material according to any one of claims 1 to 6, wherein the water / binder ratio is 10% by mass or more and 30% by mass or less. The maximum tensile strength obtained by curing the hydraulic material according to any one of claims 1 to 7 is 10 N / mm ² or more, and the tensile strength at 1% deformation is tensile. A hydraulic material cured body that is at least two-thirds of the maximum value of strength and has a tensile strength at 2% tensile deformation of at least one-third of the maximum value of tensile strength.