JP2011012437A - Cement stairs - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide cement stairs having a simple configuration and capable of achieving high efficiency of production and simplifying classification when disposing them.SOLUTION: The cement stairs are constituted by fixing both ends of a step board (20) to open strings (10) by connecting male members with female members by screws. The step board (20) is formed of a cement extrusion molded body having the property causing multiple crack and destruction when applying bending load on the step board (20) and has at least two through holes (25) in the direction of extrusion. An insert bar (30) is inserted and fixed in the through hole (25) after extrusion molding, and is provided with connection parts (32a, 32b) having either of the male members or the female members, at both ends of a bar member (31). By engaging the male members or the female members in the connection parts (32a, 32b) with the other female members or the male members (50), the step board (20) and the open strings (10) are mutually connected and fixed.

Description

  The present invention relates to a cement-based staircase.

For example, the structure shown in the exploded view of FIG. 6 is conventionally known as a staircase structure installed in an outdoor part of an apartment house.
In this staircase structure, elongated plate-like support materials 10 called sasara girders (or side girders) are arranged on both sides, and a plurality of step plates 20 'are sandwiched therebetween to constitute a staircase.

  Each step plate 20 'is provided with a bolt 30' protruding from its end face. On the other hand, a bolt hole 11 through which the bolt 30 'is passed is formed in the sasara girder 10, and the bolt 30' is passed through the bolt hole 11, and both are fixed using a nut (not shown). Alternatively, a nut may be embedded in the step plate 20 ′, and both may be connected to the bolt hole 11 from the outside of the sasara beam 10 through a bolt.

  In the case where such a corrugated plate 20 ′ is manufactured using a cement-based material, “extrusion molding” has been widely used. This is because “molding” has lower production efficiency than “extrusion molding” and is not suitable for mass production.

For example, in Patent Document 1, a tread board is formed by extrusion molding from a mortar material, and an elongated rod-shaped reinforcing rod is embedded in the tread board at the time of extrusion molding. Screws that function as nuts are fixed to both ends of the reinforcing rod, and a tread plate is connected to the Sasara beam by connecting bolts passed through the bolt holes of the Sasara beam to these screws.
However, when extruding the tread, it is necessary to align the end surface of the tread plate with the end surface of the screw tube, but it is difficult to accurately perform this.
Thus, although extrusion molding has high production efficiency and is suitable for mass production, there is a problem that it is difficult to align the nut (or bolt) embedded in the extrusion molding.

Further, for example, in Patent Document 2, a nut is not embedded in the tread board during extrusion molding, but is inserted from the outside after extrusion molding. That is, after a tread having a through hole extending in the longitudinal direction is extruded, a cylindrical nut is fitted into the through hole from the outside, and is fixed using an adhesive.
However, the work of separating the concrete material and the metal nut at the time of disposal becomes troublesome.

  Therefore, it is also conceivable to construct the tread using “molding” instead of “extrusion molding”, and in that case, positioning of the embedded nuts and bolts can be easily performed by precast, “Molding” has poor production efficiency, and the task of separating the concrete material from the metal nuts or bolts at the time of disposal is also troublesome.

JP-A-7-119269 JP-A-4-166546

  An object of the present invention is to provide a cement-based staircase having a simple structure, high production efficiency, and easy separation at the time of disposal.

The present invention is a cement-based staircase in which a step plate (20) is fixed to a sasara girder (10) at both ends thereof using a screw connection by a male member and a female member,
The corrugated plate (20) is made of a cement-based extruded product exhibiting the property of causing multiple cracks when bent and loaded, and has at least two or more through holes (25) along the extrusion direction. The insert muscle (30) is inserted and fixed in the hole (25),
Insert bars (30) are provided with connecting portions (32a, 32b) having either the male member or the female member at both ends of the bar (31),
The step plate (20) and the sasara girder (10) are connected and fixed by engaging the other female member or male member with the male member or female member of the connecting portion (32a, 32b). It relates to a cement-based staircase.

In the cementitious staircase of the present invention, an insert bar is inserted and fixed to a through hole of the step plate with respect to the step plate extruded with a through hole. Therefore, it is easy to align the step plate and the insert bar.
In addition, since the alignment of the insert bars is easy without using precast (molding), the extruded molded body is used as a step plate, so that the production efficiency is higher than when using molding.
Further, since the step plate and the sasara girder are connected and fixed by the connecting portions of the insert bars at both ends, the separation at the time of disposal is easy.
In addition, since the insert bar is inserted and fixed in the through hole of the step plate, and the step plate is made of a cement-based extruded body that exhibits the property of causing multiple cracks upon bending loading, the step plate has sufficient strength. .

  By rotating the cross section of the through hole into a non-circular shape and making the cross section of the connecting portion of the insert bar fit into the through hole, the insert bar rotates in the through hole (idle during screwing). Can be prevented. In that case, it is not necessary to fix the insert muscle in the through hole by using an adhesive or the like. Furthermore, by injecting an adhesive into the gap between the through hole and the insert bar, it is possible to prevent the insert bar from rattling in the through hole, and to achieve a stronger fixation between the through hole and the insert bar. .

The exploded view for demonstrating the structure of the cement-type staircase which concerns on this invention. The perspective view for demonstrating the step board which concerns on one Embodiment of this invention. The figure for demonstrating the insert reinforcement inserted and fixed to a corrugated board. The figure for demonstrating an example of the rotation prevention means of an insert muscle in this invention. The principal part perspective view for demonstrating the aspect which fixes the step board of FIG. 2 to a sasara girder. The exploded view for demonstrating the structure of the conventional staircase. The figure for demonstrating the cross-sectional shape and size of the corrugated board manufactured by the reference example 1. FIG. The graph which shows the measurement result of the bending strength performed in the reference example 1, Example 1, and Comparative Examples 1-2. The schematic diagram for demonstrating the measuring method of bending strength.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
The cementitious staircase according to the present invention is formed by connecting and fixing one or more step plates 20 to the Sasara girder 10 at both ends thereof as shown in FIG. The connection / fixation of the step plate 20 and the sasara girder 10 is performed by connecting the engaging member 50 through the bolt hole 11 of the sasara beam 10 and the connecting portion (the insert bars 30 in the through hole of the step plate 20 are provided at both ends). 32a, 32b).

(Corrugated board)
FIG. 2 is a perspective view showing an example of the corrugated board 20. The step board 20 has a through-hole 25 extending along its entire length along the extrusion direction, and the insert bar 30 is inserted and fixed therein. The insert bar 30 is inserted and fixed in the through hole 25 after the step plate 20 is extruded. Thus, in the present invention, after the step plate 20 having the through-holes 25 is first extruded, the insert bar 30 is inserted and fixed from the outside, and therefore, the positioning of the insert bar 30 with respect to the step plate 20 is simple. Therefore, it is possible to easily position the insert bars 30 while ensuring high production efficiency by extrusion.

  The step plate 20 may be an extruded body integrally including a tread plate 21 and a kick plate 22 as shown in FIG. 2, or may be an extrudate formed only of the tread plate 21. As a material to be used, a hydraulic cement composition described later in detail is used.

  The through hole 25 is for inserting the insert muscle 30. The number of through holes 25 is at least 2 per step plate. The number of through-holes 25 may be set as appropriate according to the depth of the step board 20, particularly the tread board 21. In particular, 2-3 is preferable.

  The through hole 25 may be formed by one or more in each of the tread plate 21 and the kick plate 22, but the through hole must not be formed in the kick plate 22. Usually, it is preferable that two or more through holes are formed in the tread plate 21.

  The size of the through hole 25 is not particularly limited as long as the insertion of the insert bar 30 is achieved. For example, from the viewpoint of the strength of the step board, when the thickness of the tread is t, the length of the through hole 25 in the tread thickness direction The thickness is preferably 0.2 to 0.7 t.

The cross-sectional shape of the through hole 25 is not particularly limited, and may be, for example, a circular shape or a non-circular shape such as an elliptical shape, a polygonal shape, or a star shape. The step plate 20 is extruded, and the through hole 25 is formed at the same time. Therefore, the through hole 25 has a constant cross-sectional shape over the entire length.
In the present specification, the cross-sectional shape is a shape in a cross section perpendicular to the extrusion direction.

  The step plate 20 may have a through hole 26 for weight reduction along the extrusion direction. The cross-sectional shape of the weight reduction through hole 26 is not particularly limited, and may be, for example, an ellipse as shown in FIG. 2 or a circle. In FIG. 2, all the through holes having an elliptical cross-sectional shape are through holes 26 for weight reduction.

  The size of the step board 20 is not particularly limited. For example, from the viewpoint of easy climbing, balance between weight reduction and strength, the tread board 21 has a depth of 150 to 500 mm, the tread board 21 has a thickness of 40 to 80 mm, and the tread board. The total width of 21 is preferably 600 to 1500 mm, the height of the kick plate 22 is 100 to 300 mm, and the thickness of the kick plate 22 is preferably 20 to 80 mm. Of course, it is not limited to these.

(Insert muscle)
The insert bar 30 includes connecting portions 32 a and 32 b at both ends of the bar 31. Thus, since the connection parts 32a and 32b are integrated via the bar 31, separation at the time of disposal is easy.

  FIG. 3 shows an example of the insert muscle. The illustrated insert bar 30 is configured by welding and fixing hexagonal nuts 32a and 32b as connecting portions to both ends of a bar 31 made of a deformed steel bar. In the example of FIGS. 1 to 3, a configuration is adopted in which the connecting portions 32 a and 32 b are formed as female members (nuts), and bolts (male members) as the engaging members 50 are screw-engaged thereto. However, the reverse configuration can also be adopted. That is, it is possible to employ a configuration in which the connecting portions 32a and 32b are provided with a bolt portion protruding from the end face, and a nut as the engaging member 50 is engaged with the bolt portion. Further, it is possible to provide a female member at the connecting portion 32a and a male member at the connecting portion 32b (or vice versa).

  It is preferable to set the full length of the insert bar 30 equal to the total length of the step plate 20. Thereby, when the insert bars 30 are arranged in the step plate 20, the end surfaces of both the connecting portions 32 a and 32 b are flush with the end surface 20 a of the step plate 20.

  The bar 31 only needs to have a smaller diameter than at least the connecting portions 32a and 32b at both ends, and need not be a deformed bar. Moreover, the insert bar | burr 30 may have a fixed cross-sectional shape over the full length including the connection parts 32a and 32b.

  The material constituting the bar 31 and the connecting portions 32a and 32b of the insert bar 30 is not particularly limited as long as the connection / fixation between the step plate 20 and the sasara girder 10 is achieved. For example, steel, iron, mild steel wire, Examples include metals such as steel bars for reinforced concrete and rolled steel for structures.

  In order to prevent rotation (idling) of the insert bar 30 in the through hole 25 during construction, the insert bar 30 is fixed in the through hole 25. The fixing of the insert bar 30 may be achieved by injecting an adhesive into the gap between the through hole 25 and the insert bar 30 and curing it, or, as will be described in detail later, the connecting part of the through hole and the insert bar. It may be achieved by making the cross-sectional shape of this into a predetermined shape. From the viewpoint of more reliably achieving the fixation, it is preferable to achieve the fixation of the insert muscle 30 by setting the cross-sectional shape of the connecting portion of the insert muscle to a predetermined shape. In order to prevent rattling of the insert muscles 30 in the through-holes 25 that are inserted and fixed even when the insert muscles 30 are fixed by setting the cross-sectional shape of the connecting portion of the insert muscles to a predetermined shape. In addition, it is preferable to inject an adhesive into the gap between the through hole 25 and the insert bar 30 and harden it. The adhesive is not particularly limited as long as the fixation within the through hole of the insert muscle can be achieved, and rattling may be prevented by using a so-called sealing agent or caulking agent.

(Sasara digit)
The two sasara girders 10 are used to sandwich one or more step plates 20.
The material which comprises the sasara girder 10 is not restrict | limited especially as long as a corrugated board can be supported, For example, steel, iron, rolled steel for structure, a cement-type material, etc. are mentioned.

(Prevents rotation of the insert muscle using the cross-sectional shape)
Examples of the rotation preventing means for the insert muscle 30 include the following means. That is, the cross-sectional shape of the through hole 25 and the connecting portions 32a and 32b is defined as “the connecting portions 32a and 32b are accommodated in the through hole 25, and the shapes of the two cooperate to prevent rotation of the insert muscle 30”. Shape. For this purpose, it is sufficient that the through-hole 25 has a non-circular cross-sectional shape and the connecting portions 32a and 32b of the insert bar 30 have a cross-sectional shape that does not idle in the non-circular through-hole 25. Specifically, the connecting portions 32a and 32b have a cross-sectional shape that fits in the non-circular through hole 25 and cooperates with the non-circular cross-section to prevent rotation of the insert bar 30 in the through hole. It is.

  In the example of FIGS. 1 to 3, there is provided a means for preventing rotation (idling) of the insert bar utilizing such a cross-sectional shape. Specifically, the connecting portions 32a and 32b provided at both ends of the insert bar 30 are nuts having a regular hexagonal cross section. And the through-hole 25 of the step board 20 is made into the shape which accommodates the said regular hexagon and can prevent rotation of the insert reinforcement 30. FIG. This will be described with reference to FIG.

As shown partially enlarged in FIG. 4, the cross-sectional shape of the through hole 25 is “star shape having 12 vertices”. If it is the said shape, even if it is the attitude | position shown by (a) and the attitude | position shown by (b), the insert muscle 30 can be hold | maintained non-rotatably by the nut (connection part 32a) of a regular hexagon cross section. it can.
That is, the “star shape having twelve vertices” herein is a shape constituted by two regular hexagonal outer contours that are arranged so that the centers coincide with each other and are shifted by approximately 30 °.

  In FIG. 4, for easy understanding, the connecting portion 32 a having a regular hexagonal cross section is indicated by a broken line, and the gap is exaggerated more than actual.

  From the viewpoint of holding the insert bar 30 non-rotatably (that is, preventing idling during screwing work), the cross-sectional shape of the through hole 25 does not have to be a “star shape having 12 vertices”. It may be a regular hexagon. However, by adopting the “star shape having 12 vertices”, the connecting portion 32a can be held in both the postures (a) and (b) in FIG. That is, there is a merit that the degree of freedom of work when inserting and fixing the insert bar 30 into the through hole 25 is increased, and the work efficiency is increased. In particular, the connecting portions 32a and 32b provided at both ends of the insert bar 30 are usually fixed by welding, and it is very difficult to accurately match the hexagonal apexes of the connecting portions 32a and 32b. By making the cross-sectional shape of the through hole 25 a dodecagon, it is possible to absorb the positional deviation between the two connecting portions. In addition, it cannot be overemphasized that the vertex part in the step board 25 as a cement-type extrusion molding body, ie, the dodecagon corner | angular part, has a little roundness on the characteristic of a material.

  In the illustrated example, only the connecting portions 32a and 32b at both ends have the cross-sectional shape described above, and the insert bar 30 has a relatively small-diameter bar (atypical steel bar) 31 and the connecting portions 32a and 32b at both ends. Are connected and fixed. Since the bar 31 has a small diameter, the entire insert bar 30 can be easily passed through the through hole 25.

(Consolidation and fixing of corrugated board and sasara girder)
After inserting and fixing the insert bar 30 into the through hole 25 of the step plate 20, as shown in FIG. 5, the bolt member as the engaging member 50 is passed through the bolt hole 11 of the sasara girder 10 and the connecting portion 32a. Engage with screws. Thereby, the corrugated board 20 and the sasara girder 10 are connected and fixed.
In FIG. 5, for convenience of explanation, the sasara girder 10 is partially illustrated by being drawn like a transparent rectangular plate, but actually, as shown in FIG. A plurality of step plates 20 are connected and fixed to form a staircase.

(Example of providing a waterproof cushioning seal material)
It is preferable to arrange a sealing material 40 (waterproof cushioning sealing material) for the purpose of waterproofing and cushioning between the step plate 20 and the sasara girder 10 (see FIG. 5).
“Waterproofing” is performed in order to prevent the insert bars 30 from corroding when they are made of metal. The “buffering” is performed to prevent the step board 20 from rattling between the sasara girders 10 and the joint end face from being damaged.
The waterproof cushioning sealing material 40 preferably has a shape (L-shaped in the example of FIG. 5) that fits the end surface 20a of the corrugated board, and an opening 41 for exposing the through hole 25 into which the insert muscle 30 is inserted and fixed. Have

  As a material of the waterproof cushioning sealing material 40, foamed plastic such as urethane, EPDM (ethylene-propylene-diene rubber), or the like is used.

(Hydraulic cement composition)
The corrugated board 20 is made of a cement-based extruded body that exhibits the property of causing multiple cracks upon fracture loading and, more specifically, an inorganic-based cured body manufactured from a hydraulic cement composition that will be described in detail below.

  In the present invention, “multiple crack” means the following. When bending stress is applied and the initial crack is formed in the hardened cement body, the stress concentrates on the cracked portion, and the normal hardened cement body breaks as it is. That is, fracture occurs at the stage of elastic deformation where the stress-strain curve becomes a straight line. Therefore, energy absorption ability is low and exhibits brittle fracture. On the other hand, even after the first crack is entered, there is a phenomenon in which the entire material does not immediately break, and a plurality of cracks are generated following the first crack. This is called multiple cracks. When multiple cracks are generated, the stress is dispersed, so even after the first cracks are generated, they can withstand increasing loads and do not break up to large strains, exhibiting high energy absorption and high toughness.

  The hydraulic cement composition constituting the step board of the present invention in which such multiple cracks occur is a fiber-reinforced hydraulic composition obtained by blending and reinforcing fibers in a matrix containing at least hydraulic cement. The matrix preferably further comprises a siliceous raw material, pulp and water-soluble cellulose, and may be admixed with an admixture such as a water reducing agent, mineral fibers and lightweight aggregate.

  The fiber blended in the present invention is not particularly limited as long as it is a reinforcing fiber that can cause multiple cracks at the time of bending loading on a cured body obtained by curing the hydraulic composition. For example, a polyvinyl alcohol fiber ( PVA fiber), polypropylene fiber (PP fiber), polyethylene fiber (PE fiber), aramid fiber, acrylic fiber, carbon fiber, polyamide fiber, polyester fiber, polybenzoxazole fiber, rayon fiber, glass fiber, Steel fiber etc. are mentioned. PVA fibers, PE fibers, PP fibers, and aramid fibers are preferable from the viewpoint of reducing production cost and causing multiple cracks more effectively, and particularly PVA fibers.

These fibers have a fiber length of 3 to 100 mm, a fiber diameter of 5 to 200 μm, and an aspect ratio of 100 to 1000. When the fiber length is shorter, the fiber diameter is larger, or the aspect ratio is smaller, the stress will be borne even if the fiber crosslinks when the crack is first caused in a state where bending stress is applied. Cannot be pulled out, and quickly pulled out and destroyed before multiple cracks occur.
On the other hand, if the fiber length is longer, the fiber diameter is smaller, or the aspect ratio is larger, the fiber itself breaks before the fiber is pulled out in a state where bending stress is applied. Multiple cracks do not occur.

  In the present invention, the “aspect ratio” of the fiber is a value obtained by dividing the fiber length by the diameter of an equivalent circle having the same area as the area of the fiber cross section.

  The PVA fiber is commonly called a vinylon fiber. When the PVA fiber is used, the fiber length is 3 to 50 mm, preferably 3 to 15 mm, particularly 6 to 12 mm, and the fiber diameter is 10 to 100 μm, preferably 20 It is desirable that it is ˜50 μm and the aspect ratio is 100 to 400, preferably 150 to 300.

The most preferred PVA fibers have in particular a fineness of 2 to 150 dtex, in particular 4 to 25 dtex, a tensile strength of 4 cN / dtex or more, in particular 6 to 20 cN / dtex.
As the fineness, an average value obtained by measuring the weight of a fixed yarn length of the fibrous material and measuring the apparent fineness at n = 5 or more is used. In addition, the thing (fine denier fiber) whose fineness cannot be measured by the weight measurement of a fixed yarn length is measured with a vibroscope.
The strength is set in advance in an atmosphere of 20 ° C. and 65% relative humidity for 24 hours, and the humidity is adjusted for 24 hours. The single fiber is 20 cm in length and the tensile speed is 10 cm / min. ”Is used. When the fiber length is shorter than 20 cm, the maximum length in the possible range of the sample is measured as the grip length.

  As such a preferred PVA fiber, commercially available Claron K-II “Powerlon” (manufactured by Kuraray Co., Ltd.) is available.

  When PP fibers are used, the fiber length is 3 to 15 mm, preferably 6 to 12 mm, the fiber diameter is 5 to 40 μm, preferably 10 to 30 μm, and the aspect ratio is 150 to 1000, preferably 200 to 700. Is desirable.

  When PE fibers are used, the fiber length is 3 to 15 mm, preferably 6 to 12 mm, the fiber diameter is 5 to 40 μm, preferably 10 to 30 μm, and the aspect ratio is 150 to 1000, preferably 200 to 700. Is desirable.

  The said fiber is mix | blended so that the volume mixing rate in the hardened | cured body after hardening may be 0.1 to 10%, Preferably it is 2 to 7%. If the fiber volume mixing ratio is smaller, the stress concentrated on the crack can not be supported and the crosslinking action cannot be exhibited. On the other hand, if the volume mixing ratio is larger, the contact portion between the fibers increases and hinders the integration with the cement, so that a sufficient reinforcing effect cannot be obtained.

A value measured by the following method is used as the “volume mixing ratio” of the fiber. The hardened cement body was cut in a direction perpendicular to the extrusion direction, and a reflected electron image of the cut surface was observed at an acceleration voltage of 25 kV using a scanning electron microscope. The fiber mixing ratio _Vf in the hardened cement body was determined as a value obtained by dividing the total cross-sectional area of the fibers on the observation surface in the field of view of the microscope by the area of the field of view of the electron microscope. As the fiber mixing rate _Vf , an average value of values measured for three different visual fields in the cut surface of the test piece was adopted.

  The hydraulic cement used in the present invention is not particularly limited as long as a hardened body can be formed by reaction with water. For example, various portland cements, blast furnace cements, fly ash cements, alumina cements, silica cements, magnesia cements, Includes all sulfate cement.

As the siliceous raw material, silica powder, blast furnace slag, silica sand, fly ash, diatomaceous earth, silica fume, amorphous silica and the like can be used. Silica stone powder and silica sand are preferred from the viewpoint of contributing to improvement in strength and dimensional stability of the corrugated board. As these siliceous raw materials, those having a specific surface area (according to the method described in JIS R 5201) of 3000 to 15000 cm ² / g are preferably used. The siliceous raw material is blended in an amount of 40 to 100 parts by weight, preferably 50 to 80 parts by weight, based on 100 parts by weight of the hydraulic cement. If the siliceous raw material is less than 40 parts by weight, the strength of the corrugated plate is lowered, and further, efflorescence is likely to occur.

  The pulp is preferably natural pulp such as cotton pulp or wood pulp. If it is a natural pulp, it will not specifically limit, The recycled pulp from not only a virgin pulp but used paper can also be used. In the case of wood pulp, either chemical pulp obtained by chemically removing lignin from the wood structure or mechanical pulp obtained by mechanically treating wood can be used. The pulp preferably has a fiber length of 0.05 to 10 mm. The pulp is blended in an amount of 0.1 to 50 parts by weight, preferably 0.5 to 15 parts by weight, based on 100 parts by weight of the hydraulic cement. If the amount is less than 0.1 parts by weight, the reinforcing effect cannot be exhibited. If the amount is more than 50 parts by weight, the dispersion becomes poor and the surface smoothness of the corrugated plate is deteriorated.

  Examples of the water-soluble cellulose include alkyl celluloses such as methyl cellulose and ethyl cellulose, hydroxyalkyl celluloses such as hydroxyethyl cellulose, hydroxy esyl methyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl cellulose, hydroxyalkyl alkyl celluloses, and carboxymethyl cellulose. Water-soluble cellulose imparts viscosity to the kneaded product and improves moldability when the components of the hydraulic composition are mixed and kneaded and extruded. The water-soluble cellulose is blended at a ratio of 0.1 to 10 parts by weight, preferably 1 to 6 parts by weight with respect to 100 parts by weight of the hydraulic cement. If it is less than 0.1 part by weight, it is not plastic and cannot be molded. On the other hand, when the amount is more than 10 parts by weight, only the cost is increased, and no further improvement in the effect can be expected.

  Examples of the mineral fiber include sepiolite, wollastonite, talc, attapulgite, rock wool and the like. Mineral fiber is blended in an amount of 0 to 40 parts by weight, preferably 3 to 25 parts by weight, per 100 parts by weight of hydraulic cement. When there are more mineral fibers than 40 weight part, the intensity | strength of a corrugated board will fall.

  Lightweight aggregates include natural lightweight aggregates such as volcanic rubble, artificial lightweight aggregates such as calcined fly ash balloons, ultralight aggregates such as pearlite perlite, obsidian perlite, vermiculite, and by-product lightweight aggregates such as expanded slag. Can be used. Pearlite perlite, obsidian perlite, and vermiculite are preferred.

  In addition to the above additives, the hydraulic composition may contain inorganic materials other than silica such as mica, alumina, calcium carbonate, water reducing agents, surfactants, thickeners, curing accelerators, etc. You can also

  The corrugated board of the present invention can be obtained by adding water to the mixture of the above components constituting the hydraulic cement composition, followed by extrusion molding and curing. By extrusion molding, the reinforcing fibers are predominantly oriented in the extrusion direction, so the reinforcement effect by the fiber cross-linking action is more effective against bending stress from the direction perpendicular to the extrusion direction or tensile stress in the extrusion direction. Can be demonstrated. Further, by extrusion molding, a denser molded body is generally obtained, and as a result, the corrugated board of the present invention having a relatively complicated shape as described above can be easily formed. In general, the amount of water is preferably 40 to 90 parts by weight per 100 parts by weight of hydraulic cement. A corrugated board can be produced by passing a mold having a predetermined cross-sectional shape through the extrudate during extrusion molding.

  In the present invention, the corrugated plate usually has a specific gravity of 1.5 to 2.5, preferably 1.8 to 2.2, and exhibits high toughness despite being relatively light. is there.

<Reference Example 1>
100 parts by weight of ordinary Portland cement, 5.1 parts by weight of PVA short fiber (Kuraray Co., Ltd., trade name “Kuraron K-II“ Powerlon ”) with a length of 6 mm and a fiber diameter of 40 μm (aspect ratio of 150) 60 parts by weight of a surface area of 4000 cm ² / g), 3 parts by weight of pulp (hardwood pulp) and 6 parts by weight of methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed with powder using a mixer. After mixing 70.0 parts by weight of water, the mixture was transferred to a kneader and kneaded to knead the cement paste, and the resulting cement paste was extruded from a cylinder type vacuum extrusion machine through a mold and extruded from the mold. The product was received on a tray, steam-cured and cured to obtain a corrugated plate having a cross-sectional shape shown in FIG.

  The bending strength of the obtained corrugated board was evaluated by the following method, and the result is shown as a solid line A in FIG. The corrugated board (hardened cement) caused multiple crack fractures in the bending test and showed high physical property values. Moreover, the volume mixing rate of the PVA fiber in the cured body was 4.0%.

(Bending strength evaluation method)
A specimen for a simple bending test with a two-point load having a length in the extrusion direction of about 1200 mm was cut out. As shown in FIG. 9, a pressure jig 120 having a diameter of 100 mm and a thickness of 20 mm was used, a load was applied thereto at a crosshead speed of 5.0 mm / min, and a bending load was measured. In addition, the distance between fulcrums was 800 mm. In FIG. 9, arrows indicate concentrated loads, and triangles indicate fulcrums.

<Example 1>
The step board was manufactured and evaluated by the same method as in Reference Example 1 except that the following insert bars were inserted into two through holes of the same step board as in Reference Example 1. The result is shown as a broken line B in FIG.
The insert bars 30 were formed by welding and fixing hexagonal nuts 32a and 32b (outer diameter 20 mm) to both ends of a bar 31 (diameter 11 mm) made of a deformed steel bar.

<Comparative Example 1>
A corrugated board was produced and evaluated in the same manner as in Reference Example 1 except that the addition amount of PVA short fibers was 1 part by weight. In addition, the obtained corrugated board did not show multiple crack fracture in the bending test. The result is shown as a solid line C in FIG. The volume mixing rate of the PVA fiber in the cured product was 0.05%.
Moreover, the bending test result of what inserted the insert bar into the step board obtained by this comparative example similarly to Example 1 was shown as the broken line D in FIG.

<Comparative Example 2>
A commercially available precast molded product corrugated board (cement specific gravity: 2.4, insert muscle diameter 11 mm, no hollow) was subjected to a bending test in the same manner as in Example 1. The result is shown as a broken line E in FIG.

  The cement-based staircase of the present invention is useful as a staircase for an apartment, a condominium, etc., a factory, a warehouse, or the like.

10: Sasara girder 11: Bolt hole 20: Step plate 20a: End surface of step plate 21: Tread plate 22: Kick plate 25: Through hole for insertion of insert bar 26: Through hole for weight reduction 30: Insert bar 31: Bar 32a: 32b: Connection part 40: Waterproof cushioning seal material 41: Opening 50: Engagement member (bolt member)

Claims (6)

A staircase is a cement-type staircase in which a step plate is fixed to a sasara girder (10) using screw connection by a male member and a female member at both ends thereof,
The corrugated plate is made of a cement-based extrusion molded body exhibiting the property of causing multiple cracks upon fracture loading, and has at least two or more through holes (25) along the extrusion direction. ) Insert muscle (30) is inserted and fixed in
Insert bars (30) are provided with connecting portions (32a, 32b) having either the male member or the female member at both ends of the bar (31),
The step plate (20) and the sasara girder (10) are connected and fixed by engaging the other female member or male member with the male member or female member of the connecting portion (32a, 32b). Cement-based staircase. The through hole (25) has a non-circular cross-sectional shape;
The cementitious staircase according to claim 1, wherein the connecting portion (32a, 32b) of the insert bar (30) has a cross-sectional shape so as not to idle in the non-circular through hole (25).   The connecting section (32a, 32b) of the insert bar (30) has a regular hexagonal cross-sectional shape, and the through-hole (25) has a star shape having 12 vertices. Item 3. A cemented staircase according to Item 2.   The cementitious staircase according to claim 2 or 3, wherein an adhesive is injected into a gap between the through hole (25) and the insert bar (30).   The cementitious staircase according to any one of claims 1 to 4, wherein the step plate (20) and the sasara girder (10) are connected and fixed with a waterproof cushioning seal material (40) sandwiched therebetween.   The water which mix | blended the fiber with the matrix in which a corrugated board contains hydraulic cement 100 weight part, siliceous raw material 40-100 weight part, pulp 0.1-50 weight part, and water-soluble cellulose 0.1-10 weight part. The cementitious staircase according to any one of claims 1 to 5, wherein the cemented staircase is manufactured from a hard cement composition, and the volume mixing ratio of the fibers in the cured body after curing is 0.1 to 10%.

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