JP6747883B2 - Road or railroad protection member and its manufacturing method - Google Patents

Description

The present invention relates to a road or railroad protection member (in particular, a rock shed or a snow shed) and a method for manufacturing the same.

Protective materials such as rock sheds and snow sheds face mountainous areas and steep cliffs in snowy areas to protect road vehicles, occupants, and pedestrians from falling rocks and avalanches, and to preserve road functions. Installed on roads and railroads. Therefore, the member for protective work is required to have impact resistance due to rock fall and avalanche, and there are mainly two types, that is, steel and concrete. Here, the steel protective member has excellent workability at the time of construction, and brittle damage is unlikely to occur, but it is necessary to periodically perform coating for corrosion prevention, which requires maintenance costs. On the other hand, concrete protection members have high impact resistance, and since maintenance costs are low because painting is not required, the burden of basic work (work such as bringing the members to the construction site and assembly and installation) is large, and However, there are cases where concrete protective members cannot be used due to restrictions on the installation location. Therefore, if the strength and toughness of the concrete can be further increased, the thickness of the member can be reduced, and the load on the foundation work is reduced accordingly.
Therefore, the applicant of the present application previously proposed a rock shed and a snow shed made of a mixture containing cement, pozzolanic fine powder, aggregate having a particle size of 2 mm or less, water, and a water reducing agent (Patent Document 1). Since these rock sheds and the like have significantly higher strength and toughness than conventional concrete, the thickness of the members can be significantly reduced and the weight can be reduced, and the labor of the basic work is reduced.

JP, 2001-226916, A

Further, the present invention has the advantages of the lock shed, etc., and can further construct a protective worker (rock shed or no shed) with improved strength and toughness to improve durability and impact resistance. An object is to provide a work member.

The present inventor, as a result of diligent studies for solving the above problems, has identified cement, silica fume having a specific BET specific surface area, inorganic powder having a specific particle size distribution, and specific aggregates having a specific size. It has been found that a road or railroad protection member included in a proportion can achieve the above-mentioned object, and thus completed the present invention. That is, the present invention is a road or railroad protection member having the following configuration.

[1] Cement, silica fume, inorganic powder, aggregate A , and aggregate B having the following characteristics (a) to (d) and at least a high-performance water reducing agent, a defoaming agent, and water are included. A member for road or railroad protection, which is composed of a hardened body of a cement composition.
(A) Cement: 55-65% by volume
(B) Silica fume having a BET specific surface area of 15 to 25 m ² /g: 5 to 25% by volume
(C) 50% Inorganic powder having a cumulative particle diameter of 0.8 to 5 μm: 15 to 35% by volume
(D) Aggregate A having a maximum particle size of 1.2 mm or less, and aggregate B having a maximum particle size of 1.2 mm or more and 13 mm or less has a total content of 25 to 40% by volume.
(However, the total content of cement, silica fume, and inorganic powder is 100% by volume.)
[2] The cement in the cement composition is formed by polishing medium-heat Portland cement particles or low-heat Portland cement particles by polishing, and shaping the angular surface portion of the cement particles into a rounded shape. Coarse particles having a diameter of 20 μm or more,
Including fine particles having a particle size of less than 20 μm generated by the polishing treatment, and
The 50% volume cumulative particle size of the cement is 10 to 18 μm, and the Blaine specific surface area is 2100 to 2900 cm ² /g.
The member for road or railroad protection according to [1] above.
[3] The road or railroad protector according to [1] or [2], wherein the cement composition further contains 3% by volume or less of one or more kinds selected from metal fibers, organic fibers, and carbon fibers. Parts.
[4] The road or railroad protection member according to any one of [1] to [3], wherein the hardened body of the cement composition has a compressive strength of 330 N/mm ² or more.
[5] The road or railroad protective work according to any one of [1] to [4], wherein the cement composition further includes aggregate B having a maximum particle size of more than 1.2 mm and 13 mm or less. Parts.
[6] The road or railroad protection member according to [5], wherein the hardened body of the cement composition has a compressive strength of 300 N/mm ² or more.

[7] A method for manufacturing a member for road or rail protection work, which includes at least the following (A) molding step, (B) room temperature curing step, (C) heat curing step, and (D) high temperature heating step.
(A) Cement, silica fume, inorganic powder, and aggregate A and aggregate B having the following characteristics (a) to (d) and a high-performance water reducing agent, an antifoaming agent, and water, at least: After kneading the cement composition containing it, it is placed in a mold to obtain an uncured molded body (B) The uncured molded body is sealed at 10 to 40° C. for 24 hours or more, and cured or cured. Normal curing, followed by demolding from the mold to obtain a cured molded body, a normal temperature curing step (C), wherein the cured molded body is steam-cured or hot-water cured at 70° C. or higher and lower than 100° C. for 6 hours or longer, A heating curing step (D) of performing one or both of autoclave curing for 1 hour or longer at 100 to 200° C. to obtain a molded body subjected to heating curing, the molded body after heating curing at 150 to 200° C. for 24 hours or more. , High temperature heating step of heating (however, heating by autoclave curing is excluded) to obtain a hardened body (a) Cement: 55 to 65% by volume
(B) Silica fume having a BET specific surface area of 15 to 25 m ² /g: 5 to 25% by volume
(C) 50% Inorganic powder having a cumulative particle diameter of 0.8 to 5 μm: 15 to 35% by volume
(D) Aggregate A having a maximum particle size of 1.2 mm or less, and aggregate B having a maximum particle size of 1.2 mm or more and 13 mm or less has a total content of 25 to 40% by volume.
(However, the total content of cement, silica fume, and inorganic powder is 100% by volume.)
[8] Manufacture of a member for road or railway protective works according to [7], wherein the cement composition further contains 3% by volume or less of one or more kinds selected from metal fiber, organic fiber, and carbon fiber. Method.
[9] The member for road or railway protective works according to [7] or [8], wherein the cement composition further contains an aggregate B having a maximum particle size of more than 1.2 mm and 13 mm or less. Production method.
[10] The road according to any one of [7] to [9], which includes a water absorption step of allowing the cured molded body to absorb water between the (B) normal temperature curing step and the (C) heat curing step. Alternatively, a method for manufacturing a railroad protection member.

Since the road or railroad protection member of the present invention has high compressive strength (for example, 300 N/mm ² or more), the member can be reduced in size and weight, so that the member can be carried into a construction site. It is possible to significantly reduce the work load of the basic work such as installation work and assembly installation.

It is a front view (one example) of a high-speed airflow stirring device, which partially includes a cross section cut in a direction perpendicular to the rotation axis of the rotor. It is a schematic diagram of the flat plate test body used for the impact resistance test.

The road or railroad protective member of the present invention has cement, silica fume, and inorganic powder having the above-mentioned characteristics and contents (hereinafter, the whole of the cement, silica fume, and inorganic powder is referred to as "powder raw material"). , And aggregate A, a high-performance water reducing agent, a defoaming agent, and water, and the like, which are members made of a hardened body of a cement composition.
The method for manufacturing a road or railroad protective member of the present invention is a manufacturing method including at least the molding step, the room temperature curing step, the heating curing step, and the high temperature heating step.
Hereinafter, the present invention will be described in detail in the order of the constituent materials of the member for road or railroad protection and the steps included in the method for manufacturing the member.

(A) Cement The type of the cement is not particularly limited and is selected from, for example, ordinary Portland cement, early strength Portland cement, super early strength Portland cement, moderate heat Portland cement, sulfate resistant Portland cement, low heat Portland cement 1 More than one species can be used.
Among these, at least one selected from moderate heat Portland cement and low heat Portland cement is preferable because the fluidity of the cement composition is improved.

Further, in order to improve the fluidity of the cement composition and the compressive strength of the cementitious hardened body obtained by hardening the composition, the cement is preferably a medium heat Portland cement or a low heat Portland cement by polishing treatment. A cement formed by shaping the angular surface portion of the cement particles into a rounded shape. The cement is a cement-polishing product containing coarse particles having a particle size of 20 μm or more and fine particles having a particle size of less than 20 μm generated by the polishing process, and a 50% volume accumulation of the cement-polishing product. It is a cement polishing-treated product having a particle size of 10 to 18 μm and a Blaine specific surface area of 2100 to 2900 cm ² /g.

The upper limit of the particle size of the coarse particles is not particularly limited and is usually 200 μm or less in consideration of the general particle size of the cement to be polished, and preferably 100 μm from the viewpoint of increasing the compressive strength of the hardened cementitious material. It is the following.
The lower limit of the particle size of the fine particles is not particularly limited, and is preferably 0.1 μm or more from the viewpoint of improving the fluidity of the cement composition and workability when manufacturing a road or railroad protective member. , And more preferably 0.5 μm or more.

50% volume cumulative particle size of the cement grinding process was preferably 10～18Myuemu, more preferably 12～16Myuemu, Blaine specific surface area is preferably 2100~2900cm ² / g, more preferably 2200~2700cm ² / It is g.
When the 50% volume cumulative particle size is 10 μm or more, the fluidity of the cement composition is improved, and when it is 18 μm or less, the compressive strength of the cementitious hardened product is higher.
Further, when the Blaine specific surface area is 2100 cm ² /g or more, the compressive strength of the cementitious hardened product is higher, and when it is 2900 cm ² /g or less, the fluidity of the cement composition is improved.

For the polishing treatment, a known polishing treatment device capable of polishing the cement particles is used. Examples of the polishing treatment device include a commercially available high-speed airflow stirring device (for example, manufactured by Nara Machinery Co., Ltd., trade name "Hybridizer NHS-3 type").
Hereinafter, the high-speed airflow stirring device will be described in detail with reference to FIG.
Cement, which is a raw material, is charged from the charging port 14 at the upper part of the high-speed airflow stirring device 10 with the opening/closing valve 18 opened, and after the charging, the opening/closing valve 18 is closed.
The injected cement enters the circulation circuit 13 through an inlet 13a of the circulation circuit provided in the middle of the circulation circuit 13, and thereafter, through an outlet 13b of the circulation circuit, inside a collision chamber 17 which is a space for accommodating an object to be treated. to go into.
After the cement is added, the rotor (rotating body) 11 arranged inside the stator 16 that is a fixed body is rotated at high speed, and a high-speed airflow is generated by the rotor 11 and the blade 12 fixed to the rotor 11, The cement in the collision chamber 17 is agitated. During agitation, the cement particles enter the circulation circuit 13 from the inlet 13a of the circulation circuit provided in the collision chamber 17, and again from the outlet 13b of the circulation circuit provided in the central portion of the collision chamber 17 to the collision chamber again. It is thrown into 17 and circulates.
In addition, in FIG. 1, an arrow indicated by a dotted line indicates a flow of particles (including cement particles, and coarse particles and fine particles generated by the polishing treatment).

By stirring, the cement particles collide with the inner wall surface of the collision chamber 17, the rotor 11 and the blade 12, and the cement particles collide with each other, whereby the cement particles are abraded, and the angular portion of the particle surface is Coarse particles having a rounded shape (particles having a particle size of 20 μm or more) and fine particles (particles having a particle size of less than 20 μm) are generated.

The rotation speed of the rotor 11 is preferably 3000 to 4200 rpm, more preferably 3500 to 4000 rpm. When the rotation speed is 3000 rpm or more, the fluidity of the cement composition is improved, and when it exceeds 4200 rpm, the effect of improving the fluidity of the cement composition is saturated. In addition, it is difficult for the rotation speed to exceed 4200 rpm in view of the performance of the high-speed airflow stirring device.
The polishing treatment time is preferably 10 to 60 minutes, more preferably 20 to 50 minutes, further preferably 20 to 40 minutes, and particularly preferably 20 to 30 minutes. When the time is 10 minutes or more, the fluidity of the cement composition is improved, and when it is more than 60 minutes, the effect of improving the fluidity of the cement composition is saturated.
The obtained cement polishing treatment product (mixture of coarse particles and fine particles) is discharged from the discharge port 15 by opening the discharge valve 19.

(B) Silica fume The BET specific surface area of the silica fume is 15 to 25 m ² /g, preferably 17 to 23 m ² /g, and more preferably 18 to 22 m ² /g. If the specific surface area is less than 15 m ² /g, the compressive strength of the cementitious hardened product will decrease, and if it exceeds 25 m ² /g, the fluidity of the cement composition will decrease.

(C) Inorganic powder The inorganic powder having a 50% volume cumulative particle diameter of 0.8 to 5 μm is, for example, quartz powder (silica powder), volcanic ash, fly ash (classified or crushed), slag powder, limestone powder, feldspar. Powders, mullite powders, alumina powders, silica sols, carbide powders, and nitride powders.
Of these, quartz powder or fly ash is preferable because it improves the fluidity of the cement composition and increases the compressive strength of the cementitious hardened product.
In the present specification, the inorganic powder having a 50% volume cumulative particle diameter of 0.8 to 5 μm does not contain cement.

The 50% volume cumulative particle diameter of the inorganic powder is 0.8 to 5 μm, preferably 1 to 4 μm, more preferably 1.1 to 3.5 μm, still more preferably 1.2 μm or more and less than 3 μm. If the particle size is less than 0.8 μm, the fluidity of the cement composition will decrease, and if it exceeds 5 μm, the compressive strength of the cementitious hardened product will decrease.
The 50% volume cumulative particle size of the inorganic powder can be determined by using a commercially available particle size distribution measuring device (for example, product name "Microtrac HRA model 9320-X100" manufactured by Nikkiso Co., Ltd.).
Specifically, a cumulative particle size curve can be created using a particle size distribution measuring device, and the 50% volume cumulative particle size can be determined from the cumulative particle size curve. At this time, 0.06 g of the sample was added to 20 cm ^{3 of} ethanol which is a solvent for dispersing the sample, and the ultrasonic dispersion device (for example, product name “US300” manufactured by Nippon Seiki Seisakusho Co., Ltd.) was used for 90 seconds. The ultrasonically dispersed sample is measured.

The maximum particle size of the inorganic powder is preferably 15 μm or less, more preferably 14 μm or less, and further preferably 13 μm or less, from the viewpoint of further increasing the compressive strength of the cementitious hardened product. The 95% volume cumulative particle diameter of the inorganic powder is preferably 8 μm or less, more preferably 7 μm or less, and further preferably 6 μm or less, from the viewpoint of further increasing the compressive strength of the hardened cementitious material.

The inorganic powder preferably contains SiO ₂ as a main component (eg, quartz powder). The content of SiO ₂ in the inorganic powder is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more in order to further increase the compressive strength of the hardened cementitious material. ..

In the cement composition, the content of cement in 100% by volume of the powder raw material is 55 to 65% by volume, preferably 57 to 63% by volume. If the content is less than 55% by volume, the compressive strength of the cementitious hardened product will decrease, and if it exceeds 65% by volume, the fluidity of the cement composition will decrease.
Further, the content of silica fume is 5 to 25% by volume, preferably 7 to 23% by volume in 100% by volume of the powder raw material. If the content is less than 5% by volume, the compressive strength of the hardened cement material will be reduced, and if it exceeds 25% by volume, the fluidity of the cement composition will be reduced.
The content of the inorganic powder in 100% by volume of the powder raw material is 15 to 35% by volume, preferably 17 to 33% by volume. If the content is less than 15% by volume, the compressive strength of the cementitious hardened product will decrease, and if it exceeds 35% by volume, the fluidity of the cement composition will decrease.

(D) Aggregate A
The aggregate A is river sand, land sand, sea sand, crushed sand, silica sand, natural emery sand, artificial fine aggregate (for example, fired fine aggregate obtained by firing slag fine aggregate, fly ash, etc., artificial emery sand. , Alumina, or a carbide (for example, a coarsely crushed product of silicon carbide, boron carbide, etc.), regenerated fine aggregate, or a mixture thereof.
The maximum particle size of the aggregate A is 1.2 mm or less, preferably 1.1 mm or less, more preferably 1.0 mm or less. If the maximum particle size is 1.2 mm or less, the compressive strength of the hardened cementitious material is high.
The particle size distribution of the aggregate A is such that the content of the aggregate having a particle size of 0.6 mm or less is 95% by mass or more and 0.3 mm or less because the fluidity of the cement composition and the compressive strength of the hardened cement material are improved. It is preferable that the content of the aggregate having the particle size of 40 to 50% by mass and the content of the aggregate having the particle size of 0.15 mm or less be 6% by mass or less.
The content of the aggregate A in the cement composition is preferably 20 to 40% by volume, more preferably 22 to 38% by volume, further preferably 30 to 37% by volume, and particularly preferably 32 to 36% by volume. When the content is 20% by volume or more, the calorific value of the cement composition and the shrinkage of the hardened cementitious material are small, and when it is 40% by volume or less, the compressive strength of the hardened cementitious material is higher.

(E) High-performance water reducing agent As the high-performance water reducing agent, a high-performance water reducing agent such as naphthalenesulfonic acid-based, melamine-based, or polycarboxylic acid-based can be used. Among these, a polycarboxylic acid-based high-performance water reducing agent is preferable because it improves the fluidity of the cement composition and the compressive strength of the hardened cementitious material.
The blending amount of the high-performance water reducing agent is preferably 0.2 to 1.5 parts by mass, and more preferably 0.4 to 1.2 parts by mass in terms of solid content with respect to 100 parts by mass of the powder raw material. .. When the amount is 0.2 parts by mass or more, the water reducing performance is improved and the fluidity of the cement composition is increased, and when the amount is 1.5 parts by mass or less, the compressive strength of the hardened cementitious material is further increased.

(F) Defoaming agent The defoaming agent may be a commercially available product. The content of the defoaming agent is preferably 0.001 to 0.1 parts by mass, more preferably 0.01 to 0.07 parts by mass, and further preferably 0.01 to 100 parts by mass of the powder raw material. It is 0.05 part by mass. When the amount is 0.001 part by mass or more, the strength developing property of the cement composition is improved, and when it exceeds 0.1 part by mass, the effect of improving the strength developing property reaches a ceiling.

(G) Water Tap water or the like can be used as the water. The amount of water blended is preferably 10 to 20 parts by mass, more preferably 11 to 18 parts by mass, and still more preferably 14 to 16 parts by mass with respect to 100 parts by mass of the powder raw material. When the amount is 10 parts by mass or more, the fluidity of the cement composition is improved, and when the amount is 20 parts by mass or less, the compressive strength of the hardened cementitious material becomes higher.

(H) Fiber The cement composition may include one or more selected from metal fibers, organic fibers, and carbon fibers from the viewpoint of improving the bending strength and breaking energy of the cemented hardened product. The content of fibers in the cement composition is preferably 3% by volume or less, more preferably 0.3 to 2.5% by volume, still more preferably 0.5 to 2.3% by volume. When the content is 3% by volume or less, the fluidity and workability of the cement composition are not deteriorated, and the bending strength and fracture energy of the hardened cementitious material are improved.

(H-1) Metal Fiber The metal fiber may be at least one selected from steel fiber, stainless fiber, and amorphous fiber. Among these, steel fiber is preferable because of its excellent strength and cost and availability.
The size of the metal fibers is preferably 0.01 to 1.0 mm in diameter and 2 to 2 in length from the viewpoint of preventing the material separation of the metal fibers in the cement composition and improving the bending strength of the cementitious hardened body. 30 mm, more preferably 0.05 to 0.5 mm in diameter and 5 to 25 mm in length. The aspect ratio (fiber length/fiber diameter) of the metal fiber is preferably 20 to 200, more preferably 40 to 150.
Furthermore, the shape of the metal fiber is preferably a shape that imparts some physical adhesive force (for example, a spiral shape or a corrugated shape) rather than a linear shape. If the shape is spiral or the like, the metal fibers and the matrix secure the stress while pulling out, so that the bending strength of the hardened cementitious material is improved.

(H-2) Organic fiber and carbon fiber The organic fiber may be one that can withstand heating in the method for producing a road or railroad protective member of the present invention described later, and examples thereof include aramid fiber and polyparaphenylene. Examples thereof include benzobisoxazole fiber, polyethylene fiber, polyaryto fiber, polypropylene fiber and the like.
Further, examples of the carbon fiber include PAN-based carbon fiber and pitch-based carbon fiber.
The dimensions of the organic fiber and the carbon fiber are preferably 0.005 to 1.0 mm in diameter and have a length of 0.005 to 1.0 mm from the viewpoint of preventing the material separation of the fibers in the cement composition and improving the fracture energy of the hardened cementitious material. 2 to 30 mm, more preferably 0.01 to 0.5 mm in diameter and 5 to 25 mm in length. The aspect ratio (fiber length/fiber diameter) of the organic fibers and the carbon fibers is preferably 20 to 200, more preferably 30 to 150.

(I) Cement composition The flow value before hardening of the mortar (which does not include aggregate B described later) composed of the cement composition is described in “JIS R 5201 (Physical test method for cement) 11. Flow test”. In the method described above, the value (hereinafter, also referred to as “0 hitting flow value”) measured without performing 15 times of drop motions is preferably 200 mm or more, more preferably 220 mm or more. When the flow value is 200 mm or more, workability at the time of manufacturing a road or railroad protection member is improved.
The compressive strength of the mortar comprising the cement composition (containing no aggregate B to be described later) is preferably 330N / mm ² or more, more preferably 350 N / mm ² or more, more preferably 370N / mm ² or more And particularly preferably 400 N/mm ² or more.
A mortar composed of a cement composition using an aggregate having a modified Mohs hardness of 9 or more (for example, natural or artificial (artificial) emery sand, coarsely crushed alumina or carbide) as the aggregate A (described later). compressive strength of not including aggregate B.) is, 450 N / mm ² or more (in particular, becomes the use of emery sand 500 N / mm ² or higher). The modified Mohs hardness is preferably 9 to 14, more preferably 9 to 13, still more preferably 10 to 13, and particularly preferably 11 to 13.

(K) Aggregate B
The cement composition used in the present invention can include an aggregate B having a maximum particle size of more than 1.2 mm and 13 mm or less.
The aggregate B is river sand, mountain sand, land sand, sea sand, crushed sand, silica sand, natural emery sand, artificial fine aggregate (for example, slag fine aggregate, fired fine aggregate obtained by firing fly ash, and the like, and Artificial Emery Sand), Recycled Fine Aggregate, River Gravel, Mountain Gravel, Land Gravel, Crushed Stone, Artificial Coarse Aggregate (for example, Slag Coarse Aggregate, Calcined Coarse Aggregate Made by Fly Ash, etc.), Recycled Coarse Bone Examples of the material include a material and a mixture thereof.
The maximum particle size of the aggregate B is preferably 13 mm or less, more preferably 12 mm or less, further preferably 11 mm or less, particularly preferably 10 mm or less. When the maximum particle diameter is 13 mm or less, the strength development of the cement composition is improved and, for example, a compression strength of 300 N/mm ² or more can be expressed.
Further, the maximum particle size of the aggregate B is a value exceeding 1.2 mm, preferably 3 mm or more, more preferably 5 mm or more, further preferably 7 mm or more, from the viewpoint of cost reduction and the like.
In the present specification, the "maximum particle size" in the case where the maximum particle size of the aggregate B is 5 mm or more means the nominal size of the smallest size sieve among the sieves through which 90% by mass or more of the entire aggregate B passes. The particle size of the aggregate B shown by (is generally known as the definition of the maximum particle size of coarse aggregate).

The minimum particle size of the aggregate B is preferably a value larger than the maximum particle size of the aggregate A, more preferably 2 mm or more, further preferably 3 mm or more, further preferably 4 mm or more, and particularly preferably 5 mm or more (in this case, , Which corresponds to coarse aggregate).
In the present specification, the minimum particle size of the aggregate B is 15 mass of the entire aggregate B in the case of accumulating from the smallest particle size to the largest particle size of the aggregate B. The particle size of the aggregate B when reaching 100%.

In the present invention, the content of the aggregate A and the aggregate B in the cement composition is preferably 25 to 40% by volume, more preferably 28 to 38% by volume, and further preferably 30 to 36% by volume. is there. When the content is 25% by volume or more, the calorific value of the cement composition and the shrinkage amount of the hardened cementitious material become small. Further, when the content is 40 vol% or less, the strength development of the cement composition is improved.
The content rate of the aggregate B with respect to the total 100% by volume of the aggregate A and the aggregate B is preferably 40% by volume or less, more preferably 30% by volume or less, and further preferably 25% by volume or less. When the content is 40% by volume or less, the strength developing property (for example, compressive strength) of the cement composition is improved.
The compressive strength of the hardened body (for example, concrete) of the cement composition containing the aggregate B is preferably 300 N/mm ² or more, more preferably 320 N/mm ² or more, further preferably 340 N/mm ² or more, particularly preferably It is 360 N/mm ² or more.

Hereinafter, a method for manufacturing a road or railroad protective member made of the cured body of the cement composition will be described in detail.
The method for producing a member for road or railroad protection of the present invention comprises a kneading process of the cement composition, and a casting step in which it is cast in a mold to obtain an uncured molded product, and an uncured molded product. After curing at 10 to 40° C. for 24 hours or more, or curing in air, the mold is removed from the mold to obtain a cured molded body at room temperature, and the cured molded body is heated to 70° C. or more and less than 100° C. In either or both of steam curing or warm water curing for 6 hours or more and autoclave curing for 1 hour or more at 100 to 200° C., a heat curing step for obtaining a heat cured molded body, and a molded body after heat curing At a temperature of 150 to 200° C. for at least 24 hours (excluding heating by autoclave curing) to obtain a road or railroad protective member (hardened body of the cement composition). ..

(A) Molding step This step is a step of kneading the cement composition and then placing it in a mold to obtain an uncured molded body.
The method of kneading the cement composition before performing the casting is not particularly limited. The device used for kneading is also not particularly limited, and a conventional mixer such as an omni mixer, a pan mixer, a biaxial kneading mixer, or a tilting cylinder mixer can be used. Furthermore, the driving (molding) method is not particularly limited.
Further, the uncured molded body in this step may be made of a cement composition in which air bubbles in the cement composition are reduced or removed. By reducing or removing air bubbles in the cement composition, the strength development of the cement composition is further improved.
The method for reducing or removing air bubbles in the cement composition includes (1) a method of kneading the cement composition under reduced pressure, and (2) a method of depressurizing the cement composition after kneading before placing it in a mold. And (3) the cement composition is placed in a mold and then depressurized to remove bubbles.

(B) Room Temperature Curing Step In this step, the uncured molded body is treated at 10 to 40° C. (preferably 15 to 30° C.) for 24 hours or longer (preferably 24-96 hours, more preferably 24-72 hours). It is a step of obtaining a cured molded body by demolding from the mold after sealing and curing in air for 24 to 48 hours).
When the curing temperature is 10°C or higher, the curing time can be shortened, and when the curing temperature is 40°C or lower, the compressive strength of the cementitious hardened body (member for road or railroad protection) can be further increased.
When the curing time is 24 hours or more, defects such as cracks and cracks are less likely to occur in the cured body during demolding.
Further, in this step, curing the shaped body is preferably 20~100N / mm ^2, more preferably when expressed compressive strength of 30~80N / mm ^2, is to demolding the cured product from the mold preferable. When the compressive strength is 20 N/mm ² or more, defects such as chips and cracks are less likely to occur in the cured body when demolding, and 100 N/mm ² or less, the cured body absorbs water with less labor in a water absorption step described later. Can be made.

(C) Heat curing step In this step, the cured body obtained in the previous step is steamed at 70°C or higher and lower than 100°C (preferably 75 to 95°C, more preferably 80 to 92°C) for 6 hours or longer. In this step, one or both of curing or warm water curing and autoclave curing at 100 to 200° C. (preferably 160 to 190° C.) for 1 hour or more is performed to obtain a heat cured molded body.
In this step, when only steam curing or warm water curing is performed, the curing time is preferably 24 hours or more, more preferably 24 to 96 hours, particularly preferably 36 to 72 hours. When only autoclave curing is performed, the curing time is preferably 8 to 60 hours, more preferably 12 to 48 hours. When performing both steam curing or warm water curing and autoclave curing (for example, when performing autoclave curing after performing steam curing or warm water curing), curing time in steam curing or warm water curing is preferably 6 to 72 hours. , More preferably 12 to 48 hours, and the curing time in autoclave curing is preferably 1 to 24 hours, more preferably 4 to 18 hours.
In this step, if the curing temperature is within the above range, the curing time can be shortened, and the compressive strength of the hardened cement material is improved. Strength is improved.

(D) High-temperature heating step In this step, the heat-cured molded body is heated at 150 to 200°C (preferably 170 to 190°C) for 24 hours or longer (preferably 24 to 72 hours, more preferably 36 to 48 hours), In this step, heating (however, heating by autoclave curing is excluded) is performed to obtain a member for road or railroad protective work (cured product of the cement composition).
The heating in this step is usually performed in a dry atmosphere (in other words, a state in which water or steam is not artificially supplied).
When the heating temperature is 150° C. or higher, the heating time can be shortened, and when the heating temperature is 200° C. or lower, the compressive strength of the cementitious hardened product is further improved. Further, when the heating time is 24 hours or more, the compressive strength of the hardened cementitious material is further improved.

(E) Water Absorption Process A water absorption process may be included between the room temperature curing process and the heat curing process so that the molded body cured in the room temperature curing process absorbs water.
Examples of the method of absorbing water in the molded body that has been aged at room temperature include a method of immersing the molded body in water. Further, in the method of immersing the molded body in water, in order to increase the water absorption amount and increase the compressive strength of the cementitious hardened body in a short time, (1) the molded body is immersed in water under reduced pressure. Method, (2) a method in which the molded body is immersed in boiling water, and then the water temperature is lowered to 40° C. or lower while the molded body is immersed, (3) the molded body is boiled After immersing in water, the molded body is taken out of boiling water and then immersed in water at 40° C. or lower, (4) the molded body is immersed in water under pressure, Alternatively, (5) a method of immersing the molded body in an aqueous solution in which a drug capable of improving water permeability into the molded body is dissolved is preferable.

Examples of the method of immersing the molded body in water under reduced pressure include a method of using equipment such as a vacuum pump and a large-sized reduced pressure container.
Examples of the method of immersing the molded body in boiling water include a method of using equipment such as a high-temperature high-pressure container and a hot-water water tank.
The time to immerse the cured molded article in water under reduced pressure or boiling water is preferably 3 minutes or more, more preferably 8 minutes or more, further preferably 20 minutes or more in order to increase the water absorption rate. is there. The upper limit of the time is preferably 60 minutes, more preferably 45 minutes in order to further increase the compressive strength of the cementitious hardened product.

When the cement composition does not contain coarse aggregate (the cement composition does not contain aggregate B, or the aggregate B in the cement composition is coarse aggregate (the minimum particle size is 5 mm The above does not apply)), the water content with respect to 100% by volume of the cured product of φ50×100 mm is preferably 0.2% by volume or more, more preferably 0.3 to 2.0% by volume, and further preferably 0. .35 to 1.7% by volume.
Further, when the cement composition contains coarse aggregate (when the aggregate B in the cement composition corresponds to the coarse aggregate), the content ratio of water to 100% by volume of the cured product of φ100×200 mm is preferably 0. 0.2% by volume or more, more preferably 0.3 to 2.0% by volume, still more preferably 0.35 to 1.7% by volume. When the water absorption of these is 0.2 vol% or more, the compressive strength of the hardened cementitious material can be further increased.

Since the road or railroad protective member of the present invention is made of a cementitious hardened material having high compressive strength, cracks and the like are less likely to occur, and the thickness of the road or railway protective member can be reduced, resulting , It is possible to reduce the labor cost by reducing the weight of road or railroad protection materials.
Further, the road or railroad protective member of the present invention has excellent wear resistance. For example, the frayed depth of the cementitious hardened body after 60 minutes measured according to "ASTM C779" is preferably 0.5 mm or less, more preferably 0.4 mm or less, and further preferably 0.3 mm or less. Is.

Further, the road or railroad protective member of the present invention is water-blocking, freeze-thaw resistant, and smoke-proof (for example, chloride ions or sulfate ions are unlikely to penetrate into the road or railway protective member). Is excellent.
The road or railroad protection member of the present invention has excellent dimensional stability. For example, a 40×40×160 mm specimen, which is measured according to “JIS A 1129-2:2010 (Mortar and Concrete Length Change Measuring Method—Part 2: Contact Gauge Method)”, is stored for 6 months. The shrinkage strain of the cementitious hardened product after the treatment is preferably 10×10 ⁻⁶ or less, more preferably 8×10 ⁻⁶ or less, and further preferably 6×10 ⁻⁶ or less.
Further, the road or railroad protection member of the present invention has high bending strength. For example, when the hardened cementitious material contains fibers, the hardened cementitious material is measured according to "JSCE Standard JSCE-G 552-2010 (bending strength and bending toughness test method of steel fiber reinforced concrete)". the flexural strength is preferably 20 N / mm ² or more, more preferably 30 N / mm ² or more, more preferably 35N / mm ² or more.

In the present invention, examples of protective workers include rock sheds and snow sheds. The protector may have a conventionally used shape, and examples thereof include (1) a rock shed or a snow shed made of a slab member (roof portion) and a pillar member, and (2) a snow shed made of an arch member.
When the above-mentioned (1) rock shed or snow shed is constructed by using the member for protective work of the present invention, the use locations of the member include a slab member (roof portion) and a pillar member, and the member is used. Only the slab member or the slab member and the pillar member may be manufactured. Further, in the case of (2) constructing a snow shed, an arch member can be cited as a use place of the member.

When the member for protective work of the present invention is a slab member for rockshed construction, the thickness thereof is preferably 6 cm or more, more preferably 8 cm or more, further preferably 10 cm or more from the viewpoint of strength and impact resistance. From the standpoint of improving workability due to ease of production and weight reduction, it is preferably 30 cm or less, more preferably 25 cm or less, and further preferably 20 cm or less. The length and width are preferably 3 m or less, more preferably 2.5 m or less, further preferably 2 m or less from the viewpoint of ease of handling, and preferably 1 m or more from the viewpoint of work efficiency. , More preferably 1.5 m or more, further preferably 2 m or more.
If the slab (roof) of the lock shed has a thickness of 30 cm or more, it is advisable to stack the slab members to construct the slab (roof).

When the member for protective work of the present invention is a column member for building a rock shed or a snow shed, it may be a prism having a side of 10 to 50 cm or a column having a diameter of 10 to 50 cm from the viewpoint of strength and impact resistance. preferable. The height of the pillar member can be determined according to the height of the rock shed or snow shed to be built, but is preferably about 4 to 7 m.

When the member for protective work of the present invention is a slab member or an arch member for building a snowshed, the thickness thereof is preferably 4 cm or more, more preferably 6 cm or more, and further preferably 8 cm from the viewpoint of strength and impact resistance. From the viewpoints of ease of production and improvement in workability due to weight reduction, it is preferably 25 cm or less, more preferably 20 cm or less, and further preferably 15 cm or less. The length and width are preferably 3 m or less, more preferably 2.5 m or less, still more preferably 2 m or less from the viewpoint of easy handling, and preferably 1 m or more from the viewpoint of work efficiency. It is more preferably 1.5 m or more, still more preferably 2 m or more.

When the member for protective work of the present invention is a slab member for building a lockshed, it is preferable to introduce prestress to the member from the viewpoint of improving the tensile strength and shear strength of the member. The prestressing method may be either a pretensioning method or a posttensioning method that has been conventionally performed, but from the viewpoint of ease of manufacturing, etc., prestressing is introduced into the slab member after high temperature heating. The post tension method is preferred.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.
[Materials used]
The materials used in Examples 1 to 17 and Comparative Example 1 are shown below.
(1) Cement: Low heat Portland cement (manufactured by Taiheiyo Cement)
(2) Silica fume A: BET specific surface area 20 m ² /g
(3) Silica fume B: BET specific surface area 17 m ² /g
(4) Inorganic powder A: silica powder, 50% volume cumulative particle diameter 2 μm, maximum particle diameter 12 μm, 95% volume cumulative particle diameter 5.8 μm
(5) Inorganic powder B: silica powder, 50% volume cumulative particle size 7 μm, maximum particle size 67 μm, 95% volume cumulative particle size 27 μm
(6) Aggregate A1 (fine aggregate): Quartz sand With a maximum particle size of 1.0 mm, a particle size distribution of 98% by mass for 0.6 mm or less, 45% by mass for 0.3 mm or less, and 3% by mass for 0.15 mm or less Was adjusted.
(7) Aggregate A2 (fine aggregate): artificial emery sand (manufactured by Uji Denki Kagaku Co., modified Mohs hardness: 12)
The particle size distribution was adjusted such that the maximum particle size was 1.0 mm, the particle size of 0.6 mm or less was 96% by mass, the particle size of 0.3 mm or less was 46% by mass, and the particle size of 0.15 mm or less was 1% by mass.
(8) Polycarboxylic acid-based high-performance water reducing agent: solid content 27.4% by mass, manufactured by Floric, trade name "Floric SF500U" [registered trademark]
(9) Defoaming agent: BASF Japan Ltd., trade name "Master Air 404" [registered trademark]
(10) Water: Tap water (11) Metal fiber: Steel fiber (diameter: 0.2 mm, length: 15 mm)
(12) Aggregate B (coarse aggregate): crushed hard sandstone 1005 (particle size: 5 to 10 mm)

[Example 1]
Table 2 shows the content of the aggregate A1 in the cement composition and the mixture prepared by mixing the content of cement and the like in 100% by volume of the powder raw material so as to be the amount shown in Example 1 of Table 2. The amount of aggregate A1 was put into an omni mixer and kneaded for 15 seconds.
Next, the amounts of water, polycarboxylic acid-based high-performance water reducing agent, and defoaming agent shown in Table 2 were put into an omni mixer and kneaded for 2 minutes.
After the kneading, the kneaded material adhering to the side wall in the omni mixer was scraped off, and the kneading was performed for 4 minutes. Then, the zero impact flow value of the cement composition after kneading was measured by the method described in "JIS R 5201 (Physical test method for cement) 11. Flow test" without performing 15 drop motions.

The obtained kneaded product was cast in a cylindrical mold frame of φ50×100 mm, then sealed and cured at 20° C. for 48 hours, and then demolded to obtain a molded product. The compressive strength during demolding was 50 N/mm ² .
This molded body was immersed in water in a desiccator under reduced pressure for the time shown in Table 3 (in Table 3, indicated as "under reduced pressure"). In addition, for the depressurization, "Aspirator (AS-01)" manufactured by AS ONE was used. The mass of the molded body before and after the immersion was measured, and the water absorption rate was calculated from the obtained measured value.
After the immersion, the molded body was steam-cured at 90° C. for 48 hours, then cooled to 20° C., and then heated at 180° C. for 48 hours.
The compressive strength of the cementitious hardened body () was measured according to "JIS A 1108 (concrete compressive strength test method)".
Further, a test piece of 30×30×6 cm was manufactured in the same manner as the cementitious hardened material, and the chamfer depth after 60 minutes was measured according to “ASTM C779”.
Table 3 shows the values of the zero impact flow value, the water absorption rate, the compressive strength, and the fray depth. It should be noted that Table 3 also shows the respective values such as zero impact flow value, water absorption rate, compressive strength, and fray depth in Examples and Comparative Examples described later.

[Example 2]
A cement composition and a cementitious hardened body were obtained in the same manner as in Example 1 except that the amount of water mixed per 100 parts by mass of the powder raw material was changed from 13 parts by mass to 15 parts by mass.
In the same manner as in Example 1, the zero flow value of the cement composition was measured. The compressive strength at the time of demolding was 45 N/mm ² .

[Example 3]
Instead of immersing the molded body after demolding in water in a desiccator under reduced pressure, after immersing it in boiling water for the time shown in Table 3, the water temperature becomes 25° C. while the molded body is immersed in water. A cement composition and a cementitious hardened body were obtained in the same manner as in Example 1 except that the cooling was performed.
In the same manner as in Example 1, the water absorption rate was calculated, and the compressive strength of the hardened cementitious material was measured.

[Example 4]
The cement composition and the cement composition were prepared in the same manner as in Example 2 except that the molded product after demolding was immersed in boiling water in the same manner as in Example 3 instead of being immersed in water in a desiccator under reduced pressure. A cementitious hardened body was obtained.
In the same manner as in Example 1, the water absorption rate was calculated, and the compressive strength of the hardened cementitious material was measured.

[Example 5]
Cement composition in the same manner as in Example 1 except that the content of silica fume A was changed from 10% by volume to 20% by volume, and the content of inorganic powder A was changed from 30% by volume to 20% by volume. And a cementitious hardened body was obtained.
In the same manner as in Example 1, measurement of the zero shot flow value and the like were performed. The compressive strength during demolding was 50 N/mm ² .

In addition, a 40×40×160 mm specimen is manufactured in the same manner as the cement hardened product, and “JIS A 1129-2:2010 Mortar and Concrete Length Change Measuring Method-Part 2: Contact Gauge Method”. The shrinkage strain when stored for 6 months was measured in accordance with the above.
Further, the water permeability of the obtained cementitious hardened body was measured according to the water level permeability test method of "Geotechnical Society Standard JGS 0311-2009 (Soil permeability test method)". As a result, no water permeation was observed, and the water permeability coefficient was "0".
Moreover, the obtained cementitious hardened body was immersed in artificial seawater for 6 months. The artificial seawater was prepared by dissolving the reagents shown in Table 1 in distilled water in the amounts shown in Table 1.
After the immersion, the concentration of chloride ions in the hardened cementitious material was measured using EPMA (manufactured by JEOL Ltd.), and the diffusion coefficient of chloride ions (indicated by "diffusion coefficient" in Table 3) was calculated. did.
Further, the obtained cementitious hardened material was used with the value measured according to "JIS A 1148 (freezing and thawing test method for concrete)", and the durability index (300 cycles) of "ASTM C666 75" was used. Was calculated. The maximum value of the durability index is 100, and the closer to the maximum value, the better the freeze-thaw resistance.

[Example 6]
The cement composition and the cement composition were prepared in the same manner as in Example 5 except that the molded product after the mold release was immersed in boiling water in the same manner as in Example 3 instead of being immersed in water in a desiccator under reduced pressure. A cementitious hardened body was obtained.
In the same manner as in Example 1, the water absorption rate was calculated, and the compressive strength of the hardened cementitious material was measured.

[Example 7]
Cement composition in the same manner as in Example 2 except that the content of silica fume A was changed from 10% by volume to 20% by volume, and the content of inorganic powder A was changed from 30% by volume to 20% by volume. And a cementitious hardened body was obtained.
In the same manner as in Example 1, measurement of the zero shot flow value and the like were performed. The compressive strength at the time of demolding was 45 N/mm ² .

[Example 8]
The cement composition was prepared in the same manner as in Example 7, except that the molded product after the mold release was immersed in boiling water in the same manner as in Example 3 instead of being immersed in water in a desiccator under reduced pressure. And a cementitious hardened body was obtained.
In the same manner as in Example 1, the water absorption was calculated, and the compressive strength and the ground depth of the hardened cementitious material were measured.
Further, in the same manner as in Example 5, the shrinkage strain and the water permeability were measured, and the chloride ion diffusion coefficient and the durability index were calculated.

[Example 9]
In the total 100% by volume of the powder raw materials, the respective contents such as cement were mixed so as to be the amounts shown in Table 2. The obtained mixture and the aggregate A1 having the content of the aggregate A1 in the cement composition shown in Table 2 were put into an omni mixer and kneaded for 15 seconds.
Next, water, a polycarboxylic acid-based high-performance water reducing agent, and an antifoaming agent were added to the omni mixer in the amounts shown in Table 2 and kneaded for 2 minutes, and then the kneaded material adhering to the side wall inside the omni mixer was scratched. It was dropped and kneading was continued for 4 minutes. Then, the amount of the metal fibers in the cement composition shown in Table 2 was added to the omni mixer, and the mixture was further kneaded for 2 minutes.
With respect to the obtained cement composition, the zero-setting flow value was measured in the same manner as in Example 1.
Further, using the obtained cement composition, a hardened cementitious material was obtained in the same manner as in Example 1.
The water absorption and the compressive strength of the obtained cementitious hardened body were measured in the same manner as in Example 1.
Furthermore, the bending strength of the obtained cementitious hardened body was measured according to "JSCE Standard JSCE-G 552-2010 (bending strength and bending toughness test method of steel fiber reinforced concrete)".

[Example 10]
The content of the metal fibers was changed from 2.2% by volume to 2.0% by volume, and the molded body after demolding was boiled in the same manner as in Example 3 instead of being immersed in water in a desiccator under reduced pressure. A cement composition and a cementitious hardened body were obtained in the same manner as in Example 9 except that immersion in water was performed.
Various physical properties of the cement composition and the cementitious hardened product were measured in the same manner as in Example 9.
Also, in the same manner as in Example 5, the permeability coefficient, chloride ion diffusion coefficient, and durability index were calculated.
Further, in the same manner as the hardened cement material, a flat plate specimen having a length of 550 mm, a width of 100 mm and a thickness of 25 mm was manufactured, and a steel weight (mass) (mass) as shown in FIG. 20 kg, tip diameter 200 mm) was changed to 10 cm for the first time, 20 cm for the second time, and 30 cm for the third time. The height of the plate was changed (increased) to allow free fall, and repeated loading was applied. The impact resistance was evaluated by the fracture. As a result, the flat plate specimen broke at the fifth drop (falling height was 50 cm).

[Example 11]
A cement composition was produced with the same composition as the cement composition of Example 10 except that the content of the metal fibers was changed from 2.0% by volume to 1.0% by volume.
Various physical properties of the cement composition and the cementitious hardened product were measured in the same manner as in Example 9.
Further, using the cement composition of Example 11, a flat plate test piece was manufactured in the same manner as in Example 10, and the impact resistance was evaluated. As a result, the flat plate specimen broke at the third drop (falling height was 30 cm).

[Example 12]
The amount of water mixed per 100 parts by mass of the powder raw material was changed from 13 parts by mass to 11 parts by mass, and the amount of the aggregate A1 was changed from 35.5% by volume to 30.0% by volume to achieve high-performance water reduction. A cement composition and a cementitious hardened product were obtained in the same manner as in Example 1 except that the compounding amount of the agent was changed from 0.69 parts by mass to 0.76 parts by mass, and the molded body was not immersed in water. Got
In the same manner as in Example 1, the zero flow value of the cement composition was measured. The compressive strength at the time of demolding was 54 N/mm ² .

[Example 13]
After demolding the molded body in boiling water for the time period shown in Table 3, the same procedure as in Example 12 was carried out except that the molded body was cooled in the water until the water temperature reached 25°C. A cement composition and a cementitious hardened body were obtained.
In the same manner as in Example 1, the water absorption was calculated, and the compressive strength of the hardened cementitious material was measured.
Further, in the same manner as in Example 5, the permeability coefficient, chloride ion diffusion coefficient, and durability index were calculated.

[Example 14]
The content of the aggregate A1 was changed from 30.0% by volume to 24.0% by volume, and the amount of the aggregate B was such that the content of the aggregate B in the cement composition was 6.0% by volume. A cement composition was produced with the same composition as the cement composition of Example 12 except for the above.
The production of the cement composition was carried out in the same manner as in Example 1, after kneading the respective materials (powder raw material, aggregate A1, water, polycarboxylic acid type high-performance water reducing agent, and defoaming agent), and further aggregate It was carried out by charging B into an omni mixer and kneading for 1 minute.
Cementitious hardening was performed in the same manner as in Example 1 except that the obtained cement composition (kneaded product) was cast in a cylindrical mold of φ100×200 mm and the molded body was not immersed in water. Got the body
In the same manner as in Example 1, the compressive strength and the like of the hardened cementitious material were measured. The compressive strength at the time of demolding was 43 N/mm ² .

[Example 15]
The content of the aggregate A1 was changed from 35.5% by volume to 28.5% by volume, and the aggregate B was used in an amount such that the content of the aggregate B in the cement composition was 7.0% by volume. A cement composition was produced with the same composition as the cement composition of Example 8 except for the above.
The cement composition was produced in the same manner as in Example 1, after kneading the respective materials (powder raw material, aggregate A1, water, polycarboxylic acid type high-performance water reducing agent, and defoaming agent), and further adding bone. Material B was put into an omni mixer and kneaded for 1 minute.
A hardened cementitious body was obtained in the same manner as in Example 8 except that the obtained cement composition (kneaded product) was cast in a cylindrical mold having a diameter of 100×200 mm.
In the same manner as in Example 1, the water absorption rate was calculated, and the compressive strength of the hardened cementitious material was measured. The compressive strength during demolding was 37 N/mm ² .
Further, in the same manner as in Example 5, the water permeability was measured, the chloride ion diffusion coefficient, and the durability index were calculated.

[Example 16]
A cement composition and a cementitious hardened body were obtained in the same manner as in Example 4 except that the aggregate A2 was used instead of the aggregate A1.
In the same manner as in Example 1, the zero-setting flow value and compressive strength of the cement composition were measured. The compressive strength during demolding was 47 N/mm ² .

[Example 17]
A cement composition and a cementitious hardened body were obtained in the same manner as in Example 12 except that the aggregate A2 was used instead of the aggregate A1.
In the same manner as in Example 1, the zero-setting flow value and compressive strength of the cement composition were measured. The compressive strength at the time of demolding was 55 N/mm ² .

[Comparative Example 1]
Table 2 shows the content of the aggregate A1 in the cement composition and the mixture obtained by mixing the content of cement and the like in 100% by volume of the powder raw material so as to be the amount shown in Comparative Example 1 of Table 2. The amount of aggregate A1 was put into an omni mixer and kneaded for 15 seconds.
Next, water, a polycarboxylic acid-based high-performance water reducing agent, and an antifoaming agent were added to the omni mixer in the amounts shown in Table 2 and kneaded for 2 minutes. After the kneading, the kneaded material adhering to the side wall inside the omni mixer was scraped off, and the kneading was further performed for 4 minutes. Using the obtained kneaded product, a hardened cementitious body was obtained in the same manner as in Example 1.
Then, with respect to the cement composition and the cementitious hardened product, each physical property was measured or calculated in the same manner as in Example 1.
Furthermore, using the cement composition of Comparative Example 1, a flat plate test piece was manufactured in the same manner as in Example 10, and the impact resistance was evaluated. As a result, the flat plate specimen broke at the first drop (falling height was 10 cm).

[Evaluation of test results]
(1) Strength From Table 3, the compressive strength of the cementitious hardened bodies of Examples 1 to 13, 16 and 17 including the aggregates A1 and A2 but not including the aggregate B (coarse aggregate) is 350 N/mm ^2. More expensive than above. In particular, in Examples 9 and 10 (the cement composition contains metal fibers), the obtained cementitious cured product had a compressive strength of 445 N/mm ² or more, which was remarkably high and a bending strength of 41 N/mm ^2. That is all.
Further, even when the aggregate B is included (Examples 14 and 15), the compressive strength of the cementitious hardened body is as high as 333 N/mm ² or more.
(2) Abrasion resistance, shrinkage strain, water permeability, etc. The hardened cementitious bodies of Examples 1, 2, 5, 8, 10, 13, and 15 have a small fray depth of 0.37 mm or less. Further, the shrinkage strains of the hardened cementitious bodies of Examples 5 and 8 are as small as 5×10 ⁻⁶ or less. Further, from the water permeability, the chloride ion diffusion coefficient, and the durability index of the cementitious hardened bodies of Examples 5, 8, 10, 13, and 15, the obtained cementitious hardened bodies were water-impervious, salt-impervious, and It can be seen that it has excellent freeze-thaw resistance.
(3) Impact resistance The cementitious hardened bodies of Examples 10 and 11 containing metal fibers were broken at the fifth and third drops, respectively, and have higher impact resistance than Comparative Example 1 below.
On the other hand, the compressive strength of the hardened cementitious body of Comparative Example 1 is 290 N/mm ^2, which is lower than that of Examples 1 to 17. Further, the ground depth of the hardened cementitious body of Comparative Example 1 is 0.57 mm, which is larger than that of the Examples. Further, the impact resistance of the cementitious hardened body of Comparative Example 1 was broken by the first drop, so the impact resistance was low.
From these results, the road or railroad protection member of the present invention has high strength and impact resistance, and has wear resistance, dimensional stability, water impermeability, freeze-thaw resistance, salt impermeability and the like. It can be seen that it has excellent durability.

10 High Speed Air Flow Stirrer 11 Rotor 12 Blade 13 Circulation Circuit 13a Circulation Circuit Inlet 13b Circulation Circuit Outlet 14 Input Port 15 Discharge Port 16 Stator 17 Collision Chamber 18 Opening Valve 19 Discharge Valve

Claims (10)

A cement composition containing at least a cement, silica fume, an inorganic powder, an aggregate A , and an aggregate B having the following characteristics (a) to (d) and a high-performance water reducing agent, an antifoaming agent, and water. A member for road or railroad protection work, which consists of a cured body of.
(A) Cement: 55-65% by volume
(B) Silica fume having a BET specific surface area of 15 to 25 m ² /g: 5 to 25% by volume
(C) 50% Inorganic powder having a cumulative particle diameter of 0.8 to 5 μm: 15 to 35% by volume
(D) Aggregate A having a maximum particle size of 1.2 mm or less, and aggregate B having a maximum particle size of 1.2 mm or more and 13 mm or less has a total content of 25 to 40% by volume.
(However, the total content of cement, silica fume, and inorganic powder is 100% by volume.)
The cement in the cement composition is obtained by polishing medium-heat Portland cement particles or low-heat Portland cement particles by polishing, and shaping the angular surface portion of the cement particles into a rounded shape, having a particle size of 20 μm. With the above coarse particles,
Including fine particles having a particle size of less than 20 μm generated by the polishing treatment, and
The 50% volume cumulative particle size of the cement is 10 to 18 μm, and the Blaine specific surface area is 2100 to 2900 cm ² /g.
The road or railroad protection member according to claim 1. The road or railroad protective member according to claim 1 or 2, wherein the cement composition further contains 3% by volume or less of one or more kinds selected from metal fibers, organic fibers, and carbon fibers. The road or railroad protection member according to any one of claims 1 to 3, wherein the hardened body in the cement composition has a compressive strength of 330 N/mm ² or more. The road or railroad protection member according to any one of claims 1 to 4, wherein the cement composition further includes an aggregate B having a maximum particle size of more than 1.2 mm and 13 mm or less. The road or railroad protection member according to claim 5, wherein the cured product of the cement composition has a compressive strength of 300 N/mm ² or more. A method for producing a member for road or railroad protection, which includes at least the following (A) molding step, (B) room temperature curing step, (C) heat curing step, and (D) high temperature heating step.
(A) At least contains cement, silica fume, inorganic powder, aggregate A , and aggregate B having the following characteristics and contents (a) to (d), a superplasticizer, a defoaming agent, and water. After the cement composition is kneaded, it is cast in a mold to obtain an uncured molded body (B) The uncured molded body is sealed at 10 to 40° C. for 24 hours or more, and cured in the air or in air. After curing, the mold is removed from the mold to obtain a cured molded body, which is a room temperature curing step (C), wherein the cured molded body is steam-cured or hot-water cured at 70°C or higher and lower than 100°C for 6 hours or longer, and Heating-curing step (D) to obtain a molded body that has been heat-cured by performing one or both of autoclave curing for 1 hour or more at ˜200° C., the molded body after heat-curing for 24 hours or more at 150-200° C., High temperature heating step of heating (however, excluding heating by autoclave curing) to obtain a hardened body (a) Cement: 55 to 65% by volume
(B) Silica fume having a BET specific surface area of 15 to 25 m ² /g: 5 to 25% by volume
(C) 50% Inorganic powder having a cumulative particle diameter of 0.8 to 5 μm: 15 to 35% by volume
(D) Aggregate A having a maximum particle size of 1.2 mm or less, and aggregate B having a maximum particle size of 1.2 mm or more and 13 mm or less has a total content of 25 to 40% by volume.
(However, the total content of cement, silica fume, and inorganic powder is 100% by volume.)
The method for producing a member for road or rail protective works according to claim 7, wherein the cement composition further contains 3% by volume or less of one or more kinds selected from metal fibers, organic fibers, and carbon fibers. The method for producing a member for road or railway protective work according to claim 7 or 8, wherein the cement composition further contains an aggregate B having a maximum particle size of more than 1.2 mm and 13 mm or less. The road or railway protection according to any one of claims 7 to 9, including a water absorption step of allowing the cured molded body to absorb water between the (B) normal temperature curing step and the (C) heat curing step. Method for manufacturing engineering member.