JP4176583B2 - Precast staircase - Google Patents

Description

  The present invention relates to a precast staircase member that can be used as a structural member such as an external staircase or an internal staircase of a building.

Conventionally, steel stairs have been used as external stairs for buildings. However, the steel staircase has the advantage that it can be constructed at a low cost and in a short construction period, but in addition to the fact that the paint for rust prevention peels off, rusting may occur or the appearance may be damaged, There is a problem that the generated metal sound resonates as noise around.
On the other hand, it is known that precast reinforced concrete members produced in advance in a factory are carried into a construction site to construct an external staircase or the like of a building.

For example, it is a staircase formed in a cantilever form on both sides of a load bearing wall that extends vertically, the load bearing wall comprising a PC load bearing wall portion that constitutes a load bearing wall body and is made of a precast reinforced concrete member, and the PC It consists of a cast-in-place concrete wall part that is integrally and continuously provided at both left and right ends of the load-bearing wall, and the staircase part is composed of PC staircase parts that are precast reinforced concrete members. However, there has been proposed a precast concrete staircase characterized in that it is joined to the above-mentioned cast-in-place concrete wall (see Patent Document 1).
This precast concrete staircase is pre-formed with precast reinforced concrete members, so there is no need for complex lightning bar processing and assembly on site, formwork, etc. It can be constructed in a short time.

Further, a staircase made of steel fiber concrete (SFRC) is also known (see Non-Patent Document 1).
Stairs made of steel fiber concrete can be improved by increasing mechanical strength such as tensile strength and bending strength compared to normal concrete by mixing steel fibers such as epoxy resin coated galvanized fiber into the concrete. It is possible to reduce the weight by making it possible to form a portion or the like as thin as about 40 mm.
JP-A-8-27983 "Concrete Product Handbook" Cement Association 1981

As described above, the precast concrete staircase described in Patent Document 1 has an advantage that it can be constructed in a short time without requiring a skilled worker because the staircase portion is previously formed of precast reinforced concrete.
However, unlike the case of constructing a multi-step staircase by combining a large number of members having a step plate portion for one step at the site, the staircase portion constituting the precast concrete staircase of Patent Document 1 is between the cast-in-place concrete wall portions. A plurality of steps having a large length dimension are integrally formed and have a large mass. Therefore, the staircase described in Patent Document 1 is not always easy to handle during transportation to the site or construction.

On the other hand, the staircase made of steel fiber concrete described in Non-Patent Document 1 includes reinforcing fiber (steel fiber) in the concrete and has high mechanical strength. There is an advantage that the weight can be reduced.
Here, the reinforcing fiber (steel fiber) has a coating layer made of a material such as an epoxy resin in order to prevent the occurrence of rust. As a result, even in the use of external staircases in buildings that often come into contact with water such as rainwater, the strength of the staircase is prevented by preventing rusting in the reinforcing fibers in the vicinity of the concrete surface where water can enter. Etc. can be maintained without lowering.

However, the coating layer for rust prevention increases the manufacturing cost of the reinforcing fiber, which in turn increases the price of the steel fiber concrete stairs.
Further, if a cementitious hardened body having a higher strength than that of steel fiber concrete can be obtained, the thickness of the step portion or the like can be further reduced to further reduce the weight.
Therefore, the present invention is a precast staircase member made of a cement-based material that does not cause noise during walking, such as a steel staircase, and is lightweight and excellent in workability and transportability to the site, and the staircase The number of components is small, and the stairs can be completed easily and quickly on site. Furthermore, the strength is reduced due to the occurrence of rust without providing a rust-preventing coating layer for the reinforcing fibers. It aims at providing the precast staircase member which does not invite.

  As a result of intensive studies to solve the above-mentioned problems, the inventor has formed a plurality of stepped portions integrally using a cement-based material having a specific composition, thereby generating noise when walking on stairs. While retaining the advantages of cement-based materials, it is lightweight and excellent in workability and transportability to the site. Also, since multiple steps are integrally formed, it is easy and quick. In addition, the present inventors have found that a staircase can be constructed on site, and that the strength is not reduced due to the occurrence of rust even if the reinforcing fiber is not provided with a coating layer for rust prevention, and the present invention has been completed.

That is, the precast step member of the present invention (Claim 1) has a tread surface portion having a thickness of 8 to 30 mm and a kick surface portion having a thickness of 8 to 30 mm, and the number of the kick surface portions is 2 to 20. and there the step portion, and sasara order portion, a precast stair member including a landing portion, the rung portion, sasara order portion and landing portions, cement, an average particle diameter of 1.0μm or less of pozzolanic quality fine powder, the maximum particle diameter 2mm or less fine aggregate, metal fibers or organic fibers, quartz powder having an average particle diameter of 3 to 20 [mu] m, an average particle size of 1mm or less fibrous particles or flaky particles, the formulation comprising a water reducing agent and water It is characterized by being a cementitious hardened body formed integrally by using .
The precast staircase member configured in this way has a step part , a sasara girder part, and a landing part formed from a specific hardened cementitious material , and thus, it is possible to reduce the weight while ensuring a practically practical strength. be able to. Further, the step portion of the plurality of stages, since the integrally formed sasara-order portion and landing portions can be site easily and quickly construction. Further, since the cementitious hardened body is very dense, water such as rain water does not penetrate into the cementitious hardened body, and therefore, the metal fiber does not have a coating layer for rust prevention. Can also be used as a reinforcing material.

Precast stair member of the present invention, the step portion, since the integrally formed sasara-order portion and landing portions, it is possible to perform the construction work of the staircase easily and quickly.
The precast staircase member of the present invention can include a handrail made of a hardened cementitious material formed by a compound similar to the compound that forms the step part , the sasara girder part, and the landing part (Claim 2 ).

Precast stair member of the present invention, the step portion, sasara order portion and a landing portion, which is formed as a cementitious cured body made from a particular formulation while ensuring practical predetermined strength, lightweight Can be achieved.
In addition, since the precast staircase member of the present invention has a plurality of step portions formed integrally, it is greatly labor-saving and efficient compared to the case where a large number of members manufactured for each tread surface are used. And it can be installed quickly.
Furthermore, since the cementitious hardened body constituting the precast staircase member of the present invention is very dense, water such as rainwater does not penetrate into the inside of the hardened cementitious body. Also in applications, metal fibers that do not have a rust-preventing coating layer can be suitably used as the material for the cementitious cured body (precast staircase member) of the present invention.

Hereinafter, the precast step member of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing an example of a stair including a precast stair member of the present invention, and FIG. 2 is an exploded perspective view showing each part of the stair shown in FIG.
In FIG. 1, a staircase 1 includes a step part 2 which is a main part of the staircase, sasara girder parts 3 and 4 provided on the left and right sides of the step part 2, an upper landing part 5, and a lower part. It consists of a landing part 6.

In the present invention, the step part 2 , the sasara girder part 3, 4, the landing parts 5, 6, and other constituent parts (for example, handrails) that are selected as necessary are specified compounds (described later ) Specifically, it is produced using cement and other materials.
In the present specification, a molded body (that is, composed of the step part 2 , the sasara girder parts 3 and 4, the landing parts 5 and 6, and other desired constituent parts) is referred to as “precast”. It is called “staircase member”. However, the precast step member may include a material (for example, a metal plate or the like) other than the above composition as long as it is integrally formed and can be conveyed as a single member.

Stile portion 2, since sasara order portion 3, 4 and landing portions 5 and 6 are formed integrally, it can be only used one mold in the factory making precast stair member, manufacturing efficiency In addition, the work when constructing stairs on the site can be saved.

  In the present specification, the “step portion” means a portion having a tread surface portion and a kick surface portion. Here, each of the tread surface portion and the kick surface portion may be formed in a flat plate shape, or may be formed in a shape in which reinforcing ribs are provided on the flat plate. Furthermore, each of the tread surface portion and the kick surface portion may be one in which a large number of mesh holes are formed (that is, an expanded metal shape).

In FIG. 2, the step portion 2 is formed by alternately and continuously forming a tread surface portion 2 a having an upper surface extending substantially horizontally and a kick surface portion 2 b having a surface extending between the tread surfaces 2 a and extending substantially vertically. The cross section cut in the vertical direction is formed as a plate-like body having a sawtooth shape.
The thickness of the tread portion 2a is 8 to 30 mm. In the present invention, since the tread portion 2a is made of a specific composition, the thickness of the tread portion 2a is made smaller than that of a conventional product (for example, made of steel fiber concrete and having a thickness of about 40 mm). Can do.
The thickness of the kick-in surface portion 2b is usually set to the same level as the tread surface portion 2a and is 8 to 30 mm.

In the example shown in FIG. 2, the step part 2 is integrally formed between the upper landing part 5 and the lower landing part 6, but when the number of steps is large, You may divide and form in a part.
The number of steps 2 (ie, the number of kick-in surface portions 2b) is 2 to 20 from the viewpoint of ease of molding, workability during conveyance and construction , and the like.
In the example shown in FIG. 2, the step portion 2 is formed with the upper end as the kick surface portion 2 b and the lower end as the step surface portion 2 a, but other forms, for example, the upper end is the step surface portion 2 a and the lower end is the kick surface portion. It may be formed as 2b. In addition, when forming the upper end or lower end of the step part 2 as the tread surface part 2a, the tread surface part 2a normally forms a continuous plane with the landing part 5 (or 6).

The sasara girder part 3 includes an upper end 3a for supporting the edge of the landing part 5, an intermediate part 3b for supporting the step part 2 in a form of coming into contact with the step part 2 from the side, and an edge of the landing part 6 And a lower end portion 3c for supporting. The sasara beam portion 4 is formed symmetrically with the sasara beam portion 3 and includes an upper end portion 4a, an intermediate portion 4b, and a lower end portion 4c.
The landing part 5 is provided between the upper surface of the upper end part 3 a of the sasara girder part 3 and the upper surface of the upper end part 4 a of the sasara girder part 4. The landing part 6 is provided between the upper surface of the lower end part 3 c of the sasara girder part 3 and the upper surface of the lower end part 4 c of the sasara girder part 4.
The thicknesses of the landing parts 5 and 6 are not particularly limited, but are usually set to the same level as the tread part 2a and are, for example, 8 to 30 mm.
Although not shown, the staircase shown in FIG. 1 can include a handrail. The handrail can be made of the same composition as the step portion 2.
The shape of the handrail is not particularly limited, and can be a conventionally used shape. The handrail may be joined to the step portion 2, the landing portion 5 and the sasara girder portion 4 with bolts or the like, or may be formed integrally with the step portion 2 or the like.

Next, a constituent material of a specific blend for forming the step portion 2 and the like and a blending ratio thereof will be described.
The compound used in the present invention is cement, pozzolanic fine powder having an average particle size of 1.0 μm or less, fine aggregate having a maximum particle size of 2 mm or less, metal fiber or organic fiber, quartz powder having an average particle size of 3 to 20 μm, It contains fibrous particles or flaky particles having an average particle size of 1 mm or less, a water reducing agent and water. In the present invention, a blend containing these materials is molded and cured to obtain a cementitious cured body having a predetermined shape, which is used for the step portion 2 and other desired components.

The type of cement used in the present invention is not particularly limited. For example, various Portland cements such as ordinary Portland cement, early-strength Portland cement, moderately hot Portland cement, low heat Portland cement, blast furnace cement, fly ash, etc. A mixed cement such as cement can be used.
In the present invention, when improving early strength development, it is preferable to use early-strength Portland cement. When improving the fluidity of the blend, moderately hot Portland cement or low heat Portland cement is used. Is preferably used.

In the present invention, a pozzolanic fine powder having an average particle size of 1.0 μm or less is used. If the average particle size exceeds 1.0 μm, the strength development of the cured body (precast step member) is lowered, which is not preferable.
Examples of the pozzolanic fine powder include silica fume, silica dust, fly ash, slag, volcanic ash, silica sol, and precipitated silica. Among these, silica fume and silica dust have an average particle size of 1.0 μm or less and are not costly because they do not need to be crushed.

The blending amount of the pozzolanic fine powder is preferably 5 to 50 parts by mass with respect to 100 parts by mass of cement from the viewpoint of fluidity of the blend and strength development of the cured body.
When the blending amount is less than 5 parts by mass or exceeds 50 parts by mass, the fluidity of the blend is lowered, and operations such as molding become difficult. In addition, the strength development and durability of the cured body (precast staircase member) are reduced, and after using the cured body, there is a possibility that a part of the cured body may be chipped or peeled off. Since deterioration may occur, it is not preferable.

In the present invention, a fine aggregate having a maximum particle size of 2 mm or less is used. If the maximum particle size of the fine aggregate exceeds 2 mm, the strength expression of the cured body is lowered, which is not preferable.
In the present invention, it is preferable to use a fine aggregate having a maximum particle size of 1.5 mm or less from the viewpoint of the strength development of the cured product.
As the fine aggregate, for example, river sand, land sand, sea sand, crushed sand, silica sand, or a mixture thereof can be used.
The amount of fine aggregate blended is 100 parts by mass of cement from the viewpoint of fluidity of the blend, strength development of the cured body, and further reduction of self-shrinkage and drying shrinkage, reduction of hydration heat generation, etc. The amount is preferably 50 to 250 parts by mass, more preferably 80 to 180 parts by mass.

In the present invention, metal fibers or organic fibers are used.
Examples of metal fibers include steel fibers and amorphous fibers. Among these, steel fibers are preferably used because they have high strength and are excellent in terms of cost and availability.
The shape and dimensions of the metal fibers are preferably a length of 2 mm or more and a length / diameter ratio of 20 or more, more preferably a length of 2 to 30 mm and a length / diameter ratio of 20 ~ 200.

If the length of the metal fiber is less than 2 mm, the effect of improving the bending strength is lowered, which is not preferable. If the length exceeds 30 mm, fiber balls are likely to be produced during kneading, which is not preferable.
If the length / diameter ratio of the metal fibers is less than 20, the number of fibers with the same blending amount (same volume) decreases, and the effect of improving the bending strength is reduced, which is not preferable. If the ratio exceeds 200, the strength of the metal fiber itself is insufficient, and it is easy to break when subjected to tension, which is not preferable.
The compounding quantity of a metal fiber is a volume ratio in a compound, Preferably it is 0.1 to 6%, More preferably, it is 0.5 to 5.5%. When the blending amount is less than 0.1%, the bending strength of the cured body may be lowered. If the blending amount exceeds 6%, the unit water amount must be increased in order to ensure workability during kneading, and the strength of the cured product may be reduced.

Examples of organic fibers include vinylon fibers, polypropylene fibers, polyethylene fibers, aramid fibers, and carbon fibers. Among these, vinylon fibers and polypropylene fibers are preferably used because they have high strength and are excellent in terms of cost and availability.
The shape and dimensions of the organic fibers are preferably 2 mm or more in length and a length / diameter ratio of 20 or more, more preferably 2 to 30 mm in length and 20 in length / diameter. ~ 500.
If the length of the organic fiber is less than 2 mm, the effect of improving the breaking strength is lowered, which is not preferable. If the length exceeds 30 mm, fiber balls are likely to be produced during kneading, which is not preferable.
If the ratio of the length / diameter of the organic fiber is less than 20, the number of organic fibers in the same blending amount (same volume) decreases, and the effect of improving the breaking strength is lowered, which is not preferable. If the ratio exceeds 500, the strength of the organic fiber itself is insufficient, and it is easy to break when subjected to tension, which is not preferable.

The compounding amount of the organic fiber is preferably 0.1 to 10%, more preferably 0.5 to 8.0%, by volume ratio in the composition. If the blending amount is less than 0.1%, the fracture energy may decrease. If the blending amount exceeds 10%, the unit water amount must be increased in order to ensure workability during kneading, and the strength of the cured product may be reduced.
In the present invention, metal fibers and organic fibers may be used in combination. In this case, the blending amount (total amount) of the metal fiber and the organic fiber is a volume ratio in the blend, and is preferably 0.1 to 10%, more preferably 0.5 to 8.0%.

In the present invention, quartz powder having an average particle diameter of 3 to 20 μm (preferably 4 to 10 μm) is used. If the average particle diameter is outside the above range, the fluidity of the blend and the strength development of the cured product are lowered, which is not preferable.
Examples of the quartz powder include quartz, amorphous quartz, opal and cristobalite silica-containing powders, and the like.
The blending amount of the quartz powder is preferably 5 to 50 parts by mass with respect to 100 parts by mass of cement from the viewpoint of fluidity of the compound and strength development of the cured body.

In the present invention, fibrous particles or flaky particles having an average particle size of 1 mm or less are used. If the average particle size exceeds 1 mm, the strength development of the cured product is lowered, which is not preferable.
In the present specification, the “particle size” of fibrous particles or flaky particles means the size of the maximum dimension (particularly, the length of fibrous particles).
Examples of the fibrous particles include wollastonite, bauxite, mullite, and the like.
Examples of the flaky particles include mica flakes, talc flakes, vermiculite flakes, and alumina flakes.

The blending amount of the fibrous particles or the flaky particles (however, when these two types of particles are used in combination) is preferably from the viewpoint of the fluidity of the blend and the strength development and toughness of the cured body. It is 3-35 mass parts with respect to 100 mass parts of cement.
In addition, as a fibrous particle, it is preferable to use a thing with a needle-like degree represented by ratio of length / diameter 3 or more from a viewpoint of improving the toughness of a hardening body.

As the water reducing agent, for example, water reducing agents such as lignin, naphthalene sulfonic acid, melamine, and polycarboxylic acid, AE water reducing agent, high performance water reducing agent, or high performance AE water reducing agent can be used. Among these, polycarboxylic acid-based high-performance water reducing agents and high-performance AE water reducing agents are preferably used because they have a large water-reducing effect.
The blending amount of the water reducing agent is preferably 0.1 to 4.0 parts by mass, more preferably 0.3 to 1.5 parts by mass in terms of solid content with respect to 100 parts by mass of cement. If the blending amount is less than 0.1 parts by mass, kneading becomes difficult and the fluidity of the blend decreases, which is not preferable. When the blending amount exceeds 4.0 parts by mass, the strength development of the cured body is lowered, which is not preferable.
The water reducing agent can be used in either liquid or powder form.

  The amount of water is preferably 10 to 30 parts by mass, more preferably 15 to 25 parts by mass with respect to 100 parts by mass of cement. If the amount is less than 10 parts by mass, kneading becomes difficult and the fluidity of the blend becomes low. When the amount exceeds 30 parts by mass, the strength development of the cured body is lowered, which is not preferable.

The kneading method of the blend is not particularly limited, for example,
(1) A method in which materials other than water and a water reducing agent are mixed in advance to prepare a premix material, and the premix material, water and water reducing agent are charged into a mixer and kneaded;
(2) A method of preparing a premix material by mixing materials other than water (however, a powdered material is used as a water reducing agent) in advance, and adding the premix and water to a mixer and kneading. ;
(3) A method in which each material is individually fed into a mixer and kneaded;
Etc.

As the mixer used for kneading, any type of mixer used for ordinary concrete kneading can be used, and examples thereof include an oscillating mixer, a pan-type mixer, and a biaxial kneading mixer.
After kneading, if the composition is put into a predetermined mold and molded, and then cured, the precast step member of the present invention consisting of a hardened cementitious body having a predetermined shape is completed. The curing method includes air curing, underwater curing, steam curing and the like.

The physical properties of the compound used in the present invention are as follows.
The composition used in the present invention has a flow value of 230 mm or more measured without performing 15 drop motions in the method described in “JIS R 5201 (Cement physical test method) 11. Flow test”. Yes, it has excellent fluidity. Therefore, it is possible to easily perform the kneading operation of the blend, the operation of putting it in the mold and molding it. In particular, even if the shape of the precast staircase member is complicated, since the compound is distributed to every corner in the mold, a molded body (precast staircase member) having a desired shape can be manufactured with high accuracy.

The cured product obtained by curing this compound expresses a compressive strength of 130 MPa or more and a bending strength of 20 MPa or more, and is structurally very dense, so that mechanical strength and durability are reduced. It is hard to occur.
In addition, even if it comes into contact with water such as rain water, water does not enter the inside of the cured body (precast staircase member), and even if the cured body contains metal fibers, the metal fibers are rusted. Does not occur, and the reinforcing effect of the metal fiber can be maintained for many years.
Furthermore, since the hardened body (precast staircase member) is not easily chipped or peeled off, pedestrians who go up and down the stairs do not get tripped up by missing parts (such as uneven parts) on the stairs, Appearance is maintained in a good state.

Hereinafter, preparation examples of the blends used in the present invention and measured values of the physical properties will be described.
[Materials used]
The following materials were used.
1) Cement; Low heat Portland cement (manufactured by Taiheiyo Cement Co., Ltd.)
2) Pozzolanic fine powder; silica fume (average particle size: 0.25 μm)
3) Fine aggregate; silica sand No. 5 4) Metal fiber; Steel fiber (diameter: 0.2 mm, length: 15 mm)
5) Organic fiber: Vinylon fiber (diameter: 0.3 mm, length: 15 mm)
6) Water reducing agent; polycarboxylic acid-based high-performance AE water reducing agent 7) Water; tap water 8) Quartz powder (average particle size: 7 μm)
9) Fibrous particles; wollastonite (average length: 0.3 mm, length / diameter ratio: 4)

[Formulation Example 1]
(1) Material and blending ratio 100 parts by mass of low heat Portland cement, 30 parts by mass of silica fume, 120 parts by mass of fine aggregate, 1.0 part by mass of high-performance AE water reducing agent (solid content conversion value), 22 parts by mass of water, quartz powder 32 parts by mass, 24 parts by mass of wollastonite, and steel fibers (volume ratio in the composition: 2%) were put into a biaxial kneader and kneaded to obtain a composition.
(2) Flow value of the blend The flow value of the blend was measured without performing 15 drop motions in the method described in “JIS R 5201 (Cement physical test method) 11. Flow test”. . As a result, the flow value was 250 mm.

(3) Strength of blend The blend was poured into a 50 mm x 100 mm mold, pre-positioned at 20 ° C for 48 hours, and then steam-cured at 90 ° C for 48 hours to obtain cured bodies (three). The compression strength (average value of the three pieces) of the cured body was 230 MPa.
The blend was poured into a 4 × 4 × 16 cm mold, pre-positioned at 20 ° C. for 48 hours, and then steam-cured at 90 ° C. for 48 hours to obtain cured bodies (3 pieces). The bending strength (average value of the three pieces) of the cured body was 45 MPa.
(4) Water permeability coefficient of blend The blend was poured into a φ50 × 100 mm mold, pre-positioned at 20 ° C. for 48 hours, and then subjected to steam curing at 90 ° C. for 48 hours to obtain cured bodies (three). The water permeability coefficient of the cured body was measured by the water level permeability test method of “Geotechnical Society Standard JGS 0231 (Soil permeability test method)”. As a result, water penetration was not observed, and the water permeability coefficient was 0.

[Formulation Example 2]
(1) Material and blending ratio 100 parts by mass of low heat Portland cement, 30 parts by mass of silica fume, 120 parts by mass of fine aggregate, 1.0 part by mass of high-performance AE water reducing agent (solid content conversion value), 22 parts by mass of water, quartz powder 32 parts by mass, 24 parts by mass of wollastonite, and vinylon fibers (volume ratio in the formulation: 3%) were charged into a biaxial kneader and kneaded to obtain a formulation.
(2) Flow value of the blend The flow value of the blend was measured without performing 15 drop motions in the method described in “JIS R 5201 (Cement physical test method) 11. Flow test”. . As a result, the flow value was 240 mm.

(3) Strength of blend The blend was poured into a 50 mm x 100 mm mold, pre-positioned at 20 ° C for 48 hours, and then steam-cured at 90 ° C for 48 hours to obtain cured bodies (three). The compression strength (average value of the three pieces) of the cured body was 150 MPa.
The blend was poured into a 4 × 4 × 16 cm mold, pre-positioned at 20 ° C. for 48 hours, and then steam-cured at 90 ° C. for 48 hours to obtain cured bodies (3 pieces). The bending strength (average value of the three pieces) of the cured body was 22 MPa.
(4) Water Permeability Coefficient of Formulation The formulation was poured into a φ50 × 100 mm mold, pre-positioned at 20 ° C. for 48 hours, and then subjected to steam curing at 90 ° C. for 48 hours to obtain a cured product. The water permeability coefficient of the cured body was measured by the water level permeability test method of “Geotechnical Society Standard JGS 0231 (Soil permeability test method)”. As a result, water penetration was not observed, and the water permeability coefficient was 0.

It is a perspective view which shows an example of the staircase containing the precast staircase member of this invention. It is a perspective view which decomposes | disassembles and shows each part of the staircase shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stairs 2 Step part 3, 4 Sasara girder part 5, 6 Landing part 2a Tread surface part 2b Kick surface part 3a, 4a Upper end part 3b, 4b Middle part 3c, 4c Lower end part

Claims (2)

A step portion having a tread surface portion having a thickness of 8 to 30 mm and a kick surface portion having a thickness of 8 to 30 mm and the number of the kick surface portions being 2 to 20, a sasara girder portion, and a landing portion A precast staircase member, wherein the step part, the sasara girder part, and the landing part are cement, fine pozzolanic powder having an average particle size of 1.0 μm or less, fine aggregate having a maximum particle size of 2 mm or less, metal fiber or It is a cementitious hardened body integrally formed using a blend containing organic fibers, quartz powder having an average particle size of 3 to 20 μm, fibrous particles or flaky particles having an average particle size of 1 mm or less, a water reducing agent and water. Precast staircase member characterized by The precast stair member, precast stair member as claimed in claim 1 comprising a handrail made of cementitious cured body formed by the formulation as described above formulation.

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