JP5800552B2 - Precast staircase - Google Patents

Description

  The present invention relates to a precast staircase member for forming one step of a staircase.

Conventionally, various techniques for constructing stairs with a precast member made of a cementitious hardened body have been proposed.
For example, a precast staircase member made of a cemented hardened body for forming a new stepped part in a form to be added forward from the stepped part of an existing staircase, wherein the cemented hardened body includes cement, pozzolanic material Proposed precast staircase member characterized by containing fine powder, inorganic powder (except for cement) having a particle size larger than that of pozzolanic fine powder, fine aggregate, water reducing agent, and water (Patent Document 1).
Since this precast step member is a molded article of a cement-based cured body containing a specific material, it can exhibit excellent appearance, strength, and durability.

Various stair blocks made of natural stone (main stone) and concrete have been proposed.
For example, a main stone integrated L-shaped staircase block has been proposed in which a tread back main stone and a kick main stone are vertically assembled and the back surface is fixed with concrete (Patent Document 2).
In the manufacturing process, this stair block was made by strengthening the bond between the stone and the concrete by applying an adhesive on the back of the tread and the kicked surface and then sprinkling the stone powder. It is.

In addition, a technique is known in which reinforcing bars are embedded in the concrete constituting the stair block to increase the strength of the entire stair block.
For example, a concrete product such as a staircase block in which a specific sheet heating element and reinforcing bars arranged on the upper surface side or the lower surface side of the sheet heating element are embedded in a flat plate portion made of concrete is proposed. (Patent Document 3).

JP 2006-183272 A JP-A-5-10010 JP-A-9-298085

Patent Document 1 described above describes that an excellent appearance, strength, and durability can be obtained by using a specific material. However, Patent Document 1 does not describe that a precast step member is produced by combining a surface forming portion made of natural stone or the like and the specific material.
Patent Document 2 described above describes a stair block formed by adhering concrete to the back of a main stone that forms a tread surface or the like. However, there is a problem that an adhesive and stone powder are required for bonding the main stone and the concrete, and it takes time and labor for the bonding work. Moreover, when the adhesive strength of the adhesive is weak, there is a possibility that the main stone and the concrete are separated after the stairs block is laid.
In the above-mentioned patent document 3, it is described that the strength of the stair block is increased by using reinforcing bars. However, the use of reinforcing bars has problems such as complicating the manufacturing process of the stair block and making it difficult to reduce the weight.

  The present invention can provide an excellent appearance by using natural stone or the like as a surface forming member, and can be easily manufactured by a simple process, and includes a surface forming member and other portions (basic portions) It is an object of the present invention to provide a lightweight precast step member without separation.

  As a result of intensive studies to solve the above problems, the present inventor has found that a surface forming portion for forming a front side portion including a tread surface and the like and a specific layer formed on the back side of the surface forming portion are laminated. It has been found that the above object can be achieved by a precast stepped member made of a cementitious hardened body portion made of a material, and the present invention has been completed.

That is, the present invention provides the following [1] to [ 6 ].
[1] A precast staircase member for forming one step of a staircase, wherein a surface forming portion for forming a front side portion including a tread surface, a step nose and a raised surface is laminated on the back side of the surface forming portion. The cementitious hardened body part is formed, and the cementitious hardened body part is cement, pozzolanic fine powder, and inorganic powder having a particle size larger than the pozzolanic fine powder (excluding cement). ), One or more fibers selected from metal fibers, organic fibers, and carbon fibers, a fine aggregate, a water reducing agent, and a cured product of water , and does not include reinforcing bars. A precast staircase member characterized by that.
[2] The precast step member according to [1], wherein the cementitious hardened body portion includes fibrous particles or flaky particles having an average particle size of 1 mm or less.
[ 3 ] The surface forming portion forms each surface in the order of a kick-up surface, a nose and a tread surface from the front side toward the rear side, and the cementitious hardened body portion on the back side of the surface forming portion is It is formed with a uniform thickness of 15 to 40 mm from the vicinity of the front nose, which is the front side, to a thickness of 15 to 40 mm, and the thickness is increased by 5 to 15 mm in the vicinity of the end on the rear side, and is fixed to the external base The precast staircase member according to the above [1] or [2] , which has a hollow portion for inserting a fixing means for carrying out.
[ 4 ] The surface forming portion forms these surfaces in the order of a nose, a tread surface and a kick-up surface from the front side toward the rear side, and the cementitious hardened body portion on the back side of the surface forming portion is A horizontal portion formed with a uniform thickness of 15 to 40 mm rearward from the rear side surface of the nose and a vertical portion formed with a uniform thickness of 15 to 40 mm downward from the upper end on the back side of the kicking surface And is fixed to an external base disposed on the outer surface of the portion where the horizontal portion and the vertical portion intersect with each other so as to form a surface continuous with each surface of the horizontal portion and the vertical portion. The precast staircase member according to [1] or [2] , including a fixing member.
[ 5 ] The precast step member according to any one of [1] to [ 4 ], wherein the surface forming portion has irregularities or grooves on the back surface thereof.
[ 6 ] The precast step member according to any one of [1] to [ 5 ], wherein the surface forming portion is made of natural stone, artificial stone, ceramics, concrete, synthetic resin, or wood.

Since the precast staircase member of the present invention can use natural stone, artificial stone (pseudostone), or the like as the surface forming member that forms the appearance when the staircase is completed, it is superior to the case of being composed only of a cementitious hardened body. Appearance can be given.
Moreover, since the precast staircase member of the present invention has a cementitious hardened body portion made of a specific material on the back surface side of the surface forming member, by forming irregularities or the like on the back surface of the surface forming member, Adhesive force with the cementitious hardened body portion can be easily and sufficiently increased, and separation between the surface forming member and the cementitious hardened body portion can be prevented. That is, the cementitious hardened body portion used in the present invention includes a pozzolanic fine powder, an inorganic powder having a larger particle size than the pozzolanic fine powder (excluding cement), etc., and is large before hardening. Since it has fluidity and exhibits a high strength after curing, it can provide a large adhesion force by entering into the irregularities formed on the back surface of the surface forming member.

In addition, the precast staircase member of the present invention can eliminate the use of adhesive means such as an adhesive by forming irregularities on the back surface of the surface forming member as described above, and can omit reinforcing bars. In some cases, it can be easily manufactured by a simple process.
Furthermore, since the precast staircase member of the present invention has a cementitious hardened body portion made of a specific material on the back surface side of the surface forming member, the thickness can be reduced and the weight can be reduced.

It is a side view which shows an example of the precast staircase member of this invention. It is a top view of the precast staircase member shown in FIG. It is a side view which shows the other example of the precast staircase member of this invention. It is a top view of the precast staircase member shown in FIG. It is sectional drawing which shows the staircase constructed | assembled using the precast staircase member shown in FIG.1 and FIG.3. It is a side view which shows the other example of the precast staircase member of this invention. It is a side view which shows the other example of the precast staircase member of this invention. It is sectional drawing which shows the staircase constructed | assembled using the precast staircase member shown in FIG.

Hereinafter, the precast staircase member of the present invention will be described with reference to the drawings.
In FIG. 1, the precast staircase member 1 is for constituting the intermediate part of the staircase except the uppermost step, as shown in FIG.
The precast staircase member 1 includes a surface forming portion (a tread surface forming member 2, a step nose forming member 3, a kick surface forming member 4) for forming a front side portion including a tread surface, a step nose and a raised surface, and the surface formed portion. And a cementitious hardened body portion 5 formed by being laminated on the back side of the material.
Examples of the material of the surface forming member made of the tread surface forming member 2 and the like include natural stone, artificial stone (pseudo stone), ceramics, concrete, synthetic resin, and wood.
Among these, tiles etc. are mentioned as a form of ceramics.
As shown in FIGS. 1 and 2, the tread surface forming member 2 is formed in a rectangular plate shape.
The upper surface of the tread surface forming member 2 forms a tread surface of a staircase and is usually formed as a flat surface.

A plurality of grooves 6 extending in the longitudinal direction of the tread surface forming member 2 (step width direction) are formed on the back surface (lower surface) of the tread surface forming member 2. The groove 6 is for increasing the adhesion between the tread surface forming member 2 and the cementitious hardened body portion 5. The size of the groove 6 is preferably 1 to 3 mm in depth and 3 to 5 mm in width from the viewpoint of adhesive force. The number of grooves 6 formed in the tread surface forming member 2 is preferably 2 to 8, more preferably 3 to 6, from the viewpoint of adhesion and manufacturing efficiency.
In the present invention, irregularities may be formed instead of the grooves 6. As the unevenness, for example, a large number of cubic concave portions are formed on the flat surface on the back surface of the tread surface forming member 2 or a large number on the flat surface on the back surface of the tread surface forming member 2. And those having a cubic convex portion formed thereon.

As shown in FIGS. 1 and 2, the nose forming member 3 is formed in a long rod shape having a substantially rectangular cross section.
Although not shown, one or more grooves extending in the longitudinal direction (the width direction of the stairs) of the nose forming member 3 may be formed on the upper surface of the nose forming member 3 to prevent a pedestrian from slipping.
A groove 7 extending in the longitudinal direction of the nose forming member 3 (the width direction of the stairs) is formed on the back surface (lower surface) of the nose forming member 3 for the same purpose as the groove 6 described above. The preferred size of the groove 7 is the same as that of the groove 6 described above. The number of grooves 7 is preferably 1-2.
In place of the grooves 7, irregularities may be formed. The example of the unevenness is the same as the above-described example of the unevenness in place of the groove 6.
Although not shown, an uneven structure can be provided on the contact surface between the nose forming member 3 and the tread surface forming member 2. For example, a plurality of concave portions can be formed on the tread surface forming member 2 and a convex portion that can be fitted into the concave portions can be formed on the nose forming member 3. By providing such a concavo-convex structure, the strength of the entire precast step member 1 can be increased.

As shown in FIGS. 1 and 2, the kick-up surface forming member 4 is formed in a rectangular plate shape.
The surface on the outer side (front side) of the kick-up surface forming member 4 forms a step-up kick surface and is usually formed as a flat surface.
On the back surface (inner surface) of the kick-up surface forming member 4, a groove 8 extending in the longitudinal direction (step width direction) of the kick-up surface forming member is formed for the same purpose as the above-described groove 6. A preferable size of the groove 8 is the same as that of the groove 6 described above. The number of the grooves 8 is preferably 2 to 8, more preferably 3 to 6, from the viewpoints of adhesion and production efficiency.
Instead of the groove 8, unevenness may be formed. The example of the unevenness is the same as the above-described example of the unevenness in place of the groove 6.
Although not shown, an uneven structure can be provided on the contact surface between the kick-up surface forming member 4 and the nose forming member 3. The example of the concavo-convex structure is the same as the above-described concavo-convex structure example on the contact surface between the nose forming member 3 and the tread surface forming member 2.

The cementitious hardened body portion 5 has a uniform thickness of preferably 15 to 40 mm, more preferably 15 to 35 mm, still more preferably 15 to 30 mm, and particularly preferably 15 to 25 mm from the vicinity of the nose forming member 3 toward the rear. In the vicinity of the rear end, the thickness is preferably 5 to 15 mm, more preferably 10 to 15 mm larger, and a fixing means (for example, a bolt) for fixing to an external base is provided. It has a cavity 9 for insertion from the side.
The “thickness in the vicinity of the end on the rear side” here refers to a thickness based on the back surface (lower surface) of the tread surface forming member 2.
A portion of the cementitious hardened body portion 5 in the vicinity of the hollow portion 9 is formed so as to include an extended portion on the rear side of the tread surface forming member 2, and as shown in FIG. The lower end of the raised surface forming member of the staircase member and the cementitious hardened body portion on the back surface thereof can be placed. Therefore, the cementitious hardened body portion 5 does not constitute the appearance of the staircase.

The shape of the cementitious cured body portion 5 in the vicinity of the nose forming member 3 is preferably formed so that the inner surface is curved as shown in FIG.
The thickness of the cementitious hardened body portion 5 directed downward from the vicinity of the nose forming member 3 is preferably 15 to 40 mm, more preferably 15 to 35 mm, still more preferably 15 to 30 mm, and particularly preferably 15 as the dimension at the lowermost end. ~ 25 mm.
In the present invention, the cementitious cured body portion 5 is formed using a specific material. Therefore, even if the thickness of the cementitious cured body portion 5 is set to be small as in the above-described preferable numerical range, the precast step member For 1, a large strength can be secured.

Next, the precast staircase member 11 for constituting the uppermost stage of the staircase will be described.
In FIG. 3, the precast staircase member 11 includes a surface forming portion (a tread surface forming member 12, a step nose forming member 13, a kick surface forming member 14) for forming a front side portion including a tread surface, a nose and a kick surface. It consists of a cementitious hardened body portion 15 formed by being laminated on the back side of the surface forming portion. In addition, the surface formation part forms each of these surfaces in the order of the kick-up surface, the nose and the tread surface from the front side to the rear side.
The details of the nose forming member 13 and the kick-up surface forming member 14 are the same as those of the nose forming member 3 and the kick-up surface forming member 4 shown in FIG.
The tread surface forming member 12 is the same as the tread surface forming member 2 except that the tread surface forming member 12 is formed up to the rear end of the precast staircase member 11. As shown in FIG. 3, the tread surface forming member 12 is formed so that only the region near the rear end portion of the precast staircase member 11 is 5 to 15 mm thinner than the other portions. Yes.

  The hardened cementitious material portion 15 is the same as the hardened cementitious material portion 5 of FIG. 1 except for the vicinity of the rear end portion of the precast step member 11. That is, the cementitious hardened body portion 15 is formed in a uniform thickness from the vicinity of the nose forming member 13 to the rear, and the thickness is preferably 5 to 15 mm near the rear end. Preferably, it has a cavity portion 19 which is 10 to 15 mm larger and for inserting a fixing means (for example, a bolt) for fixing to an external base from below. Here, the “thickness in the vicinity of the end on the rear side” refers to a thickness based on the back surface (lower surface) of the tread surface forming member 12.

The staircase shown in FIG. 5 is an example of the staircase constructed using the precast staircase members 1 and 11.
In FIG. 5, the staircase includes a staircase foundation structure 20, a support member 21 fixed to the staircase foundation structure 20, and a fixing member (a member having an L-shaped cross section; , L-shaped member) 22, a fixture (bolt, nut) 23, a precast staircase member 1 placed on the support member 21 and fixed to the L-shaped member 22, and a fixture (bolt , Nut) 24, support member 25, support member 26 fixed to support member 25, fixture (bolt, nut) 27, precast step member 11 fixed to support member 26, fixture (bolt) , Nut) 28.

The precast staircase member of the present invention can also have the form shown in FIG. 6 or FIG.
In FIG. 6, the precast staircase member 31 includes a surface forming portion (a tread surface forming member 32, a step nose forming member 33, a kick surface forming member 34) for forming a front side portion including a tread surface, a step nose and a kick surface. It consists of a cementitious hardened body portion 35 formed by being laminated on the back side of the surface forming portion, and a fixing member (a member having a L-shaped cross section; hereinafter referred to as an L-shaped member) 36.
In addition, the surface formation part forms these each surface in order of a nose, a tread surface, and a kick-up surface from the front side toward the back side. Although not shown in the drawings, the tread surface forming member 32, the nose forming member 33, and the raised surface forming member 34 are each provided with grooves 6 and 7 shown in FIG. , 8 are formed.
The cementitious hardened body part on the back side of the surface forming part has a horizontal part formed to have a uniform thickness from the rear side surface of the nose forming member 33 to the rear side, and is uniform downward from the upper end on the back side of the kicking surface. And a vertical portion formed to have a proper thickness. The thickness of the horizontal portion and the vertical portion is preferably 15 to 40 mm, more preferably 15 to 35 mm, still more preferably 15 to 30 mm, and particularly preferably 15 to 25 mm.
Further, a fixing member for fixing to an external base (a cross section is L) so that a surface continuous with each surface of the horizontal portion and the vertical portion is formed on the outer surface of the portion where the horizontal portion and the vertical portion intersect. A letter-shaped plate-like member; hereinafter referred to as an L-shaped member) 36 is disposed.

Instead of the one shown in FIG. 6, the one shown in FIG. 7 can be used. In FIG. 7, the precast staircase member 41 includes a surface forming portion (a tread surface forming member 42, a step nose forming member 43, a kick surface forming member 44) for forming a front side portion including a tread surface, a nose and a kick surface. It consists of a cementitious hardened body portion 45 formed by being laminated on the back side of the surface forming portion, and a fixing member (L-shaped member) 46. The precast staircase member 41 has the same structure as the precast staircase member 31 except for the tread surface forming member 42 and the raised surface forming member 44.
The staircase shown in FIG. 8 is an example of a staircase constructed using the precast staircase member 31.
In FIG. 8, the stairs are supported by fixing the stairs foundation structure 37, the support member 38 fixed to the stairs foundation structure 37 by welding or the like, and fixing the support member 38 and the L-shaped member 36 by welding or the like. A precast staircase member 31 fixed onto the member 38 and a flat plate member (for example, natural stone processed into a plate shape) 39 constituting the uppermost stage are included.

Next, the material for forming the cementitious hardened body portion of the precast step member of the present invention will be described.
The cementitious hardened body part is selected from cement, pozzolanic fine powder, inorganic powder having a particle size larger than the pozzolanic fine powder (excluding cement), metal fiber, organic fiber, and carbon fiber. A cured product of a composition comprising one or more fibers, a fine aggregate, a water reducing agent, and water. As a material for the composition, in addition to the above materials, fibrous particles or flaky particles having an average particle size of 1 mm or less may be further blended.
Examples of the cement used in the present invention include various Portland cements such as ordinary Portland cement, early-strength Portland cement, moderately hot Portland cement, and low heat Portland cement.
In the present invention, when trying to improve the early strength of the cured body, it is preferable to use early-strength Portland cement, and when improving the workability of the kneaded product, It is preferred to use low heat Portland cement.
The brane specific surface area of the cement is preferably 2,500 to 5,000 cm ² / g, more preferably 3,000 to 4,500 cm ² / g. When the value is less than 2,500 cm ² / g, the hydration reaction becomes inactive, and a decrease in strength development after curing may occur. If this value exceeds 5,000 cm ² / g, not only will it take time to grind the cement, but the amount of water for obtaining a predetermined fluidity will increase, resulting in a decrease in strength development after curing.

Examples of the pozzolanic fine powder used in the present invention include silica fume, silica dust, fly ash, slag, volcanic ash, silica sol, and precipitated silica.
In general, silica fume and silica dust have a BET specific surface area of 5 to 25 m ² / g and do not need to be pulverized, and thus are preferably used in the present invention.
The BET specific surface area of the pozzolanic fine powder is preferably 5 to 25 m ² / g, more preferably 5 to 15 m ² / g. When the value is less than 5 m ² / g, the strength development after curing may decrease. When the value exceeds 25 m ² / g, the amount of water for obtaining a predetermined fluidity increases, and thus strength development after curing may be reduced.
The compounding amount of the pozzolanic fine powder is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass with respect to 100 parts by mass of cement. If the amount is outside the range of 5 to 50 parts by mass, the workability of the kneaded product may be decreased, the self-shrinkage may be increased, or the strength development after curing may be decreased.

The inorganic powder used in the present invention is an inorganic powder (except for cement) having a particle size larger than that of the pozzolanic fine powder.
By mix | blending inorganic powder, the fluidity | liquidity of a kneaded material, the intensity | strength after hardening, and durability can be improved.
Examples of the inorganic powder include slag, limestone powder, feldspar, mullite, alumina powder, quartz powder, fly ash, volcanic ash, silica sol, carbide powder, and nitride powder. Among these, slag, limestone powder and quartz powder are preferably used from the viewpoints of cost and quality stability after curing.

The inorganic powder has a brane specific surface area of (a) 3,000 to 30,000 cm ² / g, preferably 4,500 to 20,000 cm ² / g, and (b) more than the brane specific surface area of cement. It is preferable to have two conditions of being a large value (when two or more kinds of inorganic powders are included, at least one of them should have a larger Blaine specific surface area than cement).
When the Blaine specific surface area of the inorganic powder is less than 3,000 cm ² / g, the workability of the kneaded product may be decreased, or the strength development property after curing may be decreased. When the Blaine specific surface area of the inorganic powder exceeds 30,000 cm ² / g, it takes time and effort to grind, making it difficult to obtain the material and reducing the workability of the kneaded product.
Since the inorganic powder has a larger Blaine specific surface area than the cement, the inorganic powder has a particle size that fills the gap between the cement and the pozzolanic fine powder. Strength development and durability can be improved.
Difference Blaine specific surface area of the inorganic powder and cement, workability and the kneaded product, from the viewpoint of strength development and durability after curing, preferably 1,000 cm ² / g or more, more preferably 2,000 cm ² / G or more.
The blending amount of the inorganic powder is preferably 5 to 55 parts by mass with respect to 100 parts by mass of cement, from the viewpoints of workability of the kneaded product, self-shrinkage, strength development after curing, durability, and the like. Preferably it is 10-55 mass parts.

In the present invention, two types of inorganic powders (inorganic powder A having a small particle size and inorganic powder B having a large particle size) having different particle sizes can be used in combination as the inorganic powder.
In this case, as the inorganic powder A and the inorganic powder B, the same type of powder (for example, limestone powder) may be used, or different types of powder (for example, limestone powder and quartz powder) may be used.
The Blaine specific surface area of the inorganic powder A is preferably 5,000 to 30,000 cm ² / g, more preferably 6,000 to 20,000 cm ² / g. The inorganic powder A preferably has a larger Blaine specific surface area than cement.
When the Blaine specific surface area of the inorganic powder A is less than 5,000 cm ² / g, the difference in Blaine specific surface area with respect to the cement and the inorganic powder B is small, and the effect of using two kinds of inorganic powders in combination is reduced. Since seed inorganic powder is used, it takes time to prepare the material, which is not preferable. When the Blaine specific surface area of the inorganic powder A exceeds 30,000 cm ² / g, it takes time to grind, making it difficult to obtain the materials and reducing the workability of the kneaded product.

Since the inorganic powder A has a Blaine specific surface area larger than that of the cement and the inorganic powder B, the inorganic powder A has a particle size that fills the gap between the cement and the inorganic powder B and the pozzolanic fine powder. That is, the workability of the kneaded product, the strength development after curing, and the durability can be further improved.
Difference of Blaine specific surface area between inorganic powder A and cement and inorganic powder B (in other words, difference of Blaine specific surface area between inorganic powder A and cement and inorganic powder B having a larger Blaine specific surface area) Is preferably 1,000 cm ² / g or more, more preferably 2,000 cm ² / g or more, from the viewpoint of improving the workability of the kneaded material, the strength development after curing, and the durability.

The Blaine specific surface area of the inorganic powder B is preferably 2,500 to 5,000 cm ² / g. When the value is less than 2,500 cm ² / g, the workability of the kneaded product may decrease, or the strength development after curing may decrease. When the value exceeds 5,000 cm ² / g, the value of the Blaine specific surface area approaches that of the inorganic powder A, so that not only the effect of using two kinds of inorganic powders is reduced, but also two kinds of inorganic powders are used. Therefore, it takes time to prepare the material, which is not preferable.
The difference in Blaine specific surface area between the cement and the inorganic powder B is preferably 100 cm ² / g or more, more preferably 200 cm ² / g or more. When the difference is 100 cm ² / g or more, the filling property of the particles constituting the kneaded product can be improved, and the workability of the kneaded product, the strength development after curing, and the durability can be improved.

The compounding amount of the inorganic powder A is preferably 1 to 50 parts by mass, more preferably 5 to 45 parts by mass with respect to 100 parts by mass of cement. The compounding amount of the inorganic powder B is preferably 1 to 40 parts by mass, more preferably 5 to 35 parts by mass with respect to 100 parts by mass of cement. When the blending amount of the inorganic powder A and the inorganic powder B is outside the above numerical range, not only the effect of using these two kinds of inorganic powders is reduced, but also the use of the two kinds of inorganic powders, Since preparation takes time, it is not preferable.
The total amount of inorganic powder A and inorganic powder B is preferably 5 to 55 parts by mass, more preferably 10 to 50 parts by mass with respect to 100 parts by mass of cement.

In the present invention, from the viewpoint of enhancing toughness after curing, it is preferable to blend fibrous particles or flaky particles having an average particle size of 1 mm or less into the kneaded product. Here, the particle size of the particle is the size of the maximum dimension (particularly, the length of the fibrous particle).
Examples of the fibrous particles include wollastonite, bauxite, mullite, and the like. As the fibrous particles, those having an acicular degree of 3 or more expressed by a ratio of length / diameter are preferably used from the viewpoint of enhancing toughness after curing.
Examples of the flaky particles include mica flakes, talc flakes, vermiculite flakes, and alumina flakes.
The blending amount of the fibrous particles and the flaky particles (the total amount when these particles are used in combination) is determined from the viewpoint of workability of the kneaded product, strength development after curing, durability, toughness and the like. Preferably it is 35 mass parts or less with respect to a mass part, More preferably, it is 5-25 mass parts.

In the present invention, from the viewpoint of greatly increasing the bending strength and fracture strength after curing, in addition to the above materials, at least one selected from metal fibers, organic fibers and carbon fibers is blended.
A metal fiber is mix | blended from a viewpoint which raises the bending strength etc. after hardening significantly.
Examples of metal fibers include steel fibers, stainless fibers, and amorphous fibers. Among these, steel fibers are preferably used because they have high strength, are easily available, and are low in cost.
The dimensions of the metal fibers are such that the diameter is 0.01 to 1 mm and the length is 2 to 30 mm from the viewpoints of preventing material separation of the metal fibers in the kneaded product and improving the bending strength after curing. Preferably, the diameter is 0.05 to 0.5 mm and the length is 5 to 25 mm. Further, the aspect ratio (fiber length / fiber diameter) of the metal fiber is preferably 20 to 200, more preferably 40 to 150.

The shape of the metal fiber is preferably a shape that imparts some physical adhesion (for example, a spiral shape or a waveform) rather than a straight shape. If it is in a spiral shape or the like, the stress is secured while the metal fibers and the matrix are pulled out, so that the bending strength is improved.
As a suitable example of a metal fiber, what consists of a steel fiber whose diameter is 0.5 mm or less and whose tensile strength is 1-3.5 GPa is mentioned, for example. The steel fibers preferably have an interfacial adhesion strength (maximum tensile force per unit area of the adhesion surface) to the matrix of the cementitious cured body having a compressive strength of 120 MPa of 3 MPa or more. The steel fiber can be processed into a corrugated or helical shape. Further, grooves or protrusions for resisting movement (slip in the longitudinal direction) with respect to the matrix can be provided on the peripheral surface of the steel fiber. Further, a metal layer having a Young's modulus smaller than that of the steel fiber (for example, one or more selected from zinc, tin, copper, aluminum, etc.) is provided on the surface of the steel fiber. Also good.
The blending amount of the metal fiber is preferably 4% or less, more preferably 0.5 to 3%, and particularly preferably 1 to 3% in terms of volume percentage in the kneaded product. If the blending amount exceeds 4%, the unit water amount increases in order to ensure fluidity and the like, and even if the blending amount is further increased, the reinforcing effect due to the metal fibers reaches a peak, and it is not economical. Since it sometimes becomes easy to produce so-called fiber balls, it is not preferable.

The organic fiber and the carbon fiber are blended from the viewpoint of increasing the breaking strength after curing.
Examples of organic fibers include vinylon fibers, polypropylene fibers, polyethylene fibers, and aramid fibers. Among these, vinylon fibers and polypropylene fibers are preferably used from the viewpoints of cost and availability.
Examples of the carbon fiber include PAN-based carbon fiber and pitch-based carbon fiber.
The dimensions of the organic fibers and carbon fibers are 0.005 to 1 mm in diameter and 2 to 30 mm in length from the viewpoint of preventing material separation of these fibers in the kneaded product and improving the breaking strength after curing. It is preferable that the diameter is 0.01 to 0.5 mm and the length is 5 to 25 mm. The aspect ratio (fiber length / fiber diameter) of the organic fiber and the carbon fiber is preferably 20 to 200, more preferably 30 to 150.
The blending amount of the organic fiber and the carbon fiber is preferably 10% or less, more preferably 1 to 9%, and particularly preferably 2 to 8% in terms of volume percentage in the kneaded product. If the amount exceeds 10%, the amount of unit water increases to ensure fluidity, and even if the blending amount is further increased, the effect of improving the strength by these fibers reaches its peak, and it is not economical. Since kneading tends to generate so-called fiber balls, it is not preferable.

As the fine aggregate, for example, river sand, land sand, sea sand, crushed sand, silica sand, or a mixture thereof can be used.
In the present invention, it is preferable to use a fine aggregate having a maximum particle size of 2 mm or less from the viewpoint of fluidity of the kneaded product, strength development after hardening, durability, and the like, and the maximum particle size is 1.5 mm. It is more preferable to use the following fine aggregates.
The blending amount of the fine aggregate is preferably 50 to 250 parts by mass, more preferably 80 to 100 parts by mass with respect to 100 parts by mass of cement from the viewpoints of workability of the kneaded product, strength development after hardening, durability, and the like. 200 parts by mass.

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, it is preferable to use a high-performance water reducing agent or a high-performance AE water reducing agent having a large water-reducing effect, and it is more preferable to use a polycarboxylic acid-based high-performance water reducing agent or a high-performance AE water reducing agent.
The blending amount of the water reducing agent is preferably 0.1 to 4 parts by mass, more preferably 0.1 to 1 part 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 may become difficult, and workability of the kneaded product may be extremely reduced. If the blending amount exceeds 4 parts by mass, material separation or significant setting delay may occur, or strength development after curing may decrease.
The water reducing agent can be used in either liquid or powder form.
The amount of water is preferably 10 to 35 parts by mass, more preferably 12 to 30 parts by mass with respect to 100 parts by mass of cement. When the amount is less than 10 parts by mass, kneading becomes difficult and disadvantages such as extremely reduced workability of the kneaded product may occur. When the amount exceeds 30 parts by mass, strength development after curing tends to be reduced.

The kneading method of each material is not particularly limited. For example, (1) materials other than water and a water reducing agent are mixed in advance to prepare a premix material, and the premix material, water And (2) preparing a powdery water reducing agent, mixing materials other than water in advance to prepare a premix material, and adding the premix material and water to the mixer. In a mixer and kneaded, and (3) a method in which each material is individually fed into a mixer and kneaded.
The mixer used for kneading may be any type used for ordinary concrete kneading, and examples thereof include an oscillating mixer, a pan type mixer, and a biaxial kneading mixer.
The physical properties of the kneaded product and its cured product used in the present invention are as follows.
The kneaded material used in the present invention has a flow value measured in the method described in “JIS R 5201 (Cement physical test method) 11. Flow test” without performing 15 drop motions (hereinafter referred to as “0 strokes”). Is called “flow value”) is 230 mm or more, and is excellent in fluidity. Therefore, the operation | work etc. which throw a kneaded material into a mold and shape | mold can be performed easily.
Cured product said kneaded material formed by curing a 100 N / mm ² or more compression strength, after expressing 20 N / mm ² or more bending strength, since structurally are very densely formed, the mechanical strength In addition, the durability is hardly lowered.

  In the precast staircase member of the present invention, a member constituting a surface forming portion (for example, a tread surface forming member, a nose forming member, and a raised surface forming member) is laid in a mold, and then a kneaded material containing the above-described cement is used. It can be manufactured by charging, molding and curing. The curing method is not particularly limited. For example, a conventional method such as air curing, wet air curing, underwater curing, heating accelerated curing (for example, steam curing, autoclave curing), or a combination thereof may be used. Can be adopted.

Hereinafter, the present invention will be described by way of examples.
[Materials used]
The following materials were used.
(1) Cement; Low heat Portland cement (manufactured by Taiheiyo Cement; Brain specific surface area: 3,200 cm ² / g)
(2) Pozzolanic fine powder; silica fume (BET specific surface area: 10 m ² / g)
(3) Inorganic powder A; quartz powder A (Blaine specific surface area: 7,500 cm ² / g)
(4) Inorganic powder B; quartz powder B (Blaine specific surface area: 4,000 cm ² / g)
(5) Fibrous particles: wollastonite (average length: 0.3 mm, length / diameter ratio: 4)
(6) Metal fiber: Steel fiber (diameter: 0.2 mm, length: 13 mm)
(7) Fine aggregate; quartz sand (maximum particle size: 0.6mm)
(8) Water reducing agent; polycarboxylic acid-based high-performance water reducing agent (9) Water; tap water

[Example 1]
Low heat Portland cement 100 parts by weight, silica fume 31 parts by weight, quartz powder A 39 parts by weight, steel fiber 2% by volume (ratio in kneaded product A), silica sand 120 parts by weight, high performance water reducing agent 1.0 part by weight (in terms of solid content) ), 22 parts by mass of water was put into a biaxial mixer and kneaded to prepare a kneaded product A.
The 0 shot flow value of the kneaded material A was 260 mm.
The kneaded product A was poured into a mold (φ50 × 100 mm), allowed to stand at 20 ° C. for 48 hours, and then subjected to steam curing at 90 ° C. for 48 hours to obtain cured bodies (three). The average value of the compressive strength of these cured bodies (three) was 210 N / mm ² .
The kneaded material A was poured into a mold (4 × 4 × 16 cm), allowed to stand at 20 ° C. for 48 hours, and then subjected to steam curing at 90 ° C. for 48 hours to obtain cured bodies (three). The average value of the bending strength of these cured bodies (3 pieces) was 40 N / mm ² .

After laying each member (a tread surface forming member, a nose forming member, and a kick-up surface forming member) constituting the surface forming portion shown in FIG. 1 in the mold, the kneaded material A is introduced, and then at 20 ° C. After standing for 48 hours, steam curing was performed at 90 ° C. for 48 hours, and the precast staircase member 1 shown in FIG. 1 (width: 385 mm, height: 160 mm, thickness indicated by reference A in the figure: 25 mm, reference B in the figure) 15 mm, the thickness indicated by symbol C in the figure: 50 mm, the thickness of the kick-up surface forming member: 20 mm, and the thickness of the cementitious hardened body portion at the lower end of the kick-up surface forming member: 20 mm) .
Similarly, a precast staircase member 11 (width: 385 mm, height: 160 mm, thickness indicated by symbol C ′ in the drawing: 50 mm) shown in FIG. 3 was produced.
The precast staircase members 1 and 11 were used to construct the staircase shown in FIG. This staircase had sufficient strength for practical use.

[Example 2]
Low heat Portland cement 100 parts by weight, silica fume 31 parts by weight, quartz powder A 26 parts by weight, quartz powder B 13 parts by weight, steel fiber 2% by volume (ratio in kneaded product B), wollastonite 20 parts by weight, silica sand 120 parts by weight, A high-performance water reducing agent 1.0 part by mass (in terms of solid content) and 22 parts by mass of water were put into a biaxial mixer and kneaded to prepare a kneaded product B.
When the physical properties of the kneaded product B were measured in the same manner as in Example 1, the 0-stroke flow value of the kneaded product was 285 mm, the compression strength of the cured product was 215 N / mm ² , and the bending strength of the cured product was 40 N / mm ² . .
Steps were constructed in the same manner as in Example 1 except that the kneaded material B was used instead of the kneaded material A. This staircase had sufficient strength for practical use.

1,11,31,41 Precast staircase member 2,12,32,42 Tread surface forming member 3,13,33,43 Nose forming member 4,14,34,44 Kick-up surface forming member 5,15,35,45 Cement Hardened body portion 6,7,8,16,17,18 Groove 9,19 Hollow portion 20,37 Stair base structure 21,25,26,38 Support member 22,36,46 Fixing member (L-shaped member )
23, 24, 27, 28 Fixing device 39 Flat member

Claims (6)

A precast staircase member for forming one step of a staircase,
A surface-forming portion for forming a front side portion including a tread surface, a nose and a raised surface, and a cementitious hardened body portion formed by being laminated on the back side of the surface-forming portion,
The cementitious hardened body part is composed of cement, pozzolanic fine powder, inorganic powder having a particle size larger than the pozzolanic fine powder (excluding cement), metal fiber, organic fiber and carbon fiber. A precast step member , which is a cured product of a composition containing at least one selected fiber, fine aggregate, water reducing agent, and water , and does not contain a reinforcing bar.   The precast staircase member according to claim 1, wherein the hardened cementitious material portion includes fibrous particles or flaky particles having an average particle size of 1 mm or less. The surface forming portion forms each of these surfaces in the order of a kick-up surface, a nose and a tread surface from the front side to the rear side,
The cementitious hardened body part on the back side of the surface forming part is formed in a uniform thickness of 15 to 40 mm from the vicinity of the nose on the front side to the rear, and in the vicinity of the end on the rear side, The precast staircase member according to claim 1 or 2 , wherein the thickness of the precast step member is increased by 5 to 15 mm and has a hollow portion for inserting a fixing means for fixing to an external base. The surface forming portion forms each surface in the order of a nose, a tread surface and a kick-up surface from the front side to the rear side,
The cementitious hardened body part on the back side of the surface forming part has a horizontal part formed with a uniform thickness of 15 to 40 mm from the rear side surface of the nose to the rear side, and downward from the upper end on the back side of the kicking surface. Are formed on the outer surface of the portion where the horizontal portion and the vertical portion intersect, and a surface continuous with each surface of the horizontal portion and the vertical portion is formed. disposed to have a fixing member for fixing to the outside of the base, precast stair member as claimed in claim 1 or 2. The precast step member according to any one of claims 1 to 4 , wherein the surface forming portion has irregularities or grooves on the back surface thereof. The precast step member according to any one of claims 1 to 5 , wherein the surface forming portion is made of natural stone, artificial stone, ceramics, concrete, synthetic resin, or wood.

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