JP2007062155A - Precast concrete plate with cotter and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a precast concrete plate with a cotter which is improved in the joining force and peeling resistance of the concrete placing surface and in the shear resistance force to shear force generated in a concrete placing surface in the longitudinal direction (support span direction), and also to provide a method for producing the concrete plate. <P>SOLUTION: On the upper surface of the precast concrete plate 1 formed in a prescribed width and a prescribed length, i.e. on the placing surface 3 of post-placed concrete 2, a plurality of the cotters 4 of an ant mold are formed continuously in the longitudinal direction of the precast concrete plate 1. A plurality of holes 5 are formed continuously in the longitudinal direction of the precast concrete plate 1 in the cross section of the precast concrete plate 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a precast concrete plate with a cotter and a manufacturing method thereof, and is used for a floor slab of a building such as a condominium, a warehouse, an office, etc. by forming a composite body integrated with concrete or mortar to be placed later. This improves the bonding strength and peeling resistance with concrete or mortar placed from the outside.

  As a floor slab of a building, a plurality of precast concrete slabs are laid out, floor reinforcement bars are placed on the precast concrete slabs, and then concrete is placed, thereby precast concrete slabs and concrete placed later Synthetic floor slabs that resist external forces are known as composites that form a single body.

  The surface of the precast concrete slab used for this kind of synthetic floor slab has various uneven cotters to improve the adhesion strength including the adhesion and shear resistance to concrete or mortar to be placed later. Is often formed.

  Conventionally, as a method of forming a concavo-convex cotter on the surface of a precast concrete plate, when manufacturing a brecast concrete plate, before the concrete hardens, a brush or needle-shaped (bar-shaped) jig is pressed against the concrete surface and dragged. There are known a method of pressing an uneven pressing die on the concrete surface, or a method of forming unevenness on the inner surface of a brecast concrete plate making form.

By the way, as a method for producing a precast concrete plate, there is known a method in which a precast concrete plate is continuously formed while moving on a long-line pallet bed while an immediate demolding continuous molding machine is moving. In the method, when forming a concavo-convex cotter on the surface of the precast concrete plate, forming a concavo-convex cotter (groove in the plate length direction) parallel to the machine traveling direction from the manufacturing method is the molding of the precast concrete plate It is considered reasonable because the concavo-convex cotter can be formed in parallel.
International Publication No. 01/14114 Pamphlet JP 09-004121 A Japanese Patent Publication No. 06-017008 Japanese Patent No. 2620145

  However, the concavo-convex cotter parallel to the longitudinal direction of the precast concrete slab has a small bonding force between the precast concrete slab and the concrete to be placed later, so that the precast concrete slab is particularly long (supporting span direction). It was thought that a sufficient shear resistance could not be expected against the shear force generated on the concrete joint surface.

  Therefore, conventionally, a concavo-convex cotter perpendicular to the longitudinal direction of the precast concrete plate or individual concavo-convex cotters is formed, and for that purpose, mortar is further placed on the concrete that has been kneaded. The concave cotter is formed by a method that is against productivity, including pressing a convex pressing die or forming a groove with a concrete cutter before or after the concrete is cured.

  The present invention was made in order to solve the above-mentioned problems, and enhances the joining force and the peeling resistance force of the concrete joint surface, and in particular, the shear force generated on the concrete joint surface in the longitudinal direction (support span direction). An object of the present invention is to provide a precast concrete plate with a cotter having a high shear resistance against the above and a method for producing the same.

  The precast concrete plate with a cotter according to claim 1, wherein the precast concrete plate with a cotter is continuously formed in a longitudinal direction by a movable placement machine, cut into a predetermined length in the longitudinal direction, and a composite body integrated with concrete to be post-cast. The ant-shaped cotter is continuously formed in the longitudinal direction on the joint surface of the concrete to be post-cast.

  In particular, the present invention has a bonding effect and peeling with concrete or mortar to be placed later, due to the restraining effect of the ant-shaped cotter formed continuously in the longitudinal direction on the joint surface of the concrete to be placed later. It was found that the resistance force is large, and this can sufficiently increase the shear resistance of the concrete joint surface in the longitudinal direction (support span direction) of the precast concrete plate.

  Until now, concavo-convex cotters parallel to the longitudinal direction formed on the concrete joint surface of precast concrete slabs have a trapezoidal shape with a narrow bottom compared to the width of the surface of the concavo-convex part due to the need for mold removal. Or it was necessary to form in circular arc shape.

  For this reason, the conventional rugged cotters have a low bonding force between the precast concrete plate and the concrete to be placed later, because the force to constrain the concrete that has been post-molded is weak, especially in the longitudinal direction ( It was thought that the shear resistance against the shear force generated on the concrete joint surface in the support span direction could not be expected.

  Therefore, the present applicant has compared the performance of the shear strength between the concavo-convex cotter perpendicular to the longitudinal direction, which is a standard cotter, and the ant cotter of the present invention.

  As a result, the mean shear stress ratio at break of the ant cotter of the present invention to the concavo-convex cotter is 0.88 times, which is about 10% smaller than that of the concavo-convex cotter. It was.

It was also found that the long-term shear allowable stress level of the concrete joint surface in this type of shear test of the Architectural Institute of Japan was sufficiently cleared (0.3 N / mm ² (3 Kg / cm ² )).

  From the above, it has been proved that the precast concrete plate with a cotter of the present invention is sufficiently practical as a floor material constituting a composite body integrated with concrete to be cast later.

  In addition, if the ant cotter is formed not only on the upper joint surface of the precast concrete plate but also on the joint surface on the side surface that becomes the joint between the normal plates, the joint should be filled with concrete or mortar. Therefore, not only the out-of-plane direction of the plates but also the effect of transmitting the shearing force in the in-plane direction can be expected.

  The precast concrete plate with a cotter according to claim 2 is characterized in that, in the precast concrete plate with a cotter according to claim 1, a plurality of horizontal stripes intersecting with the ant-shaped cotter are formed on the joint surface of the concrete. To do.

  The present invention increases the shear resistance against the shear force generated on the concrete joining surface in both the long direction (support span direction) and the short direction perpendicular to the long direction. In this case, the horizontal stripes need only be formed to a depth of about 1 to 2 mm on the top or bottom surface of the ant-shaped cotter or both the top and bottom surfaces.

  Also, this horizontal streak can be easily formed by pressing and rolling a roller having a plurality of tooth molds on the surface of the concrete immediately after the ant cotter is formed before the concrete is compacted. it can.

  The precast concrete plate with a cotter according to claim 3 is the precast concrete plate with a cotter according to claim 1 or 2, wherein a plurality of hollow holes are formed in the longitudinal direction.

  The precast concrete plate with a cotter according to claim 4 is characterized in that in the precast concrete plate with a cotter according to any one of claims 1 to 3, prestress is introduced in the longitudinal direction.

  The method for producing precast concrete with a cotter according to claim 5 is a method for producing a precast concrete plate in which a concrete plate with a cotter having an ant-shaped cotter is continuously formed in the longitudinal direction on the joint surface of concrete to be post-cast. Then, before the concrete that is continuously placed by the movable placement machine is compacted, a convex pressing die is pressed against the upper surface of the concrete to form a concave groove, and further, an ant-like shape is formed in the concave groove. The dovetail is formed by pressing a pressing die.

  In addition, by giving vibration in the longitudinal direction of the Breccast concrete plate to the convex mold, and forming the concave groove while compacting the concrete of the surface layer part, even after pressing the dovetail mold The shape of the dovetail does not change.

  In addition, this convex mold and ant-shaped mold are incorporated into the quick-release continuous molding machine (movable placement machine) described above, and on the long line pallet bed together with the quick-release continuous molding machine. By moving in the production direction of the precast concrete plate, the precast concrete plate with ant-shaped cotters can be continuously formed in the long direction, and by cutting at a predetermined position as desired, Precast concrete plates with cotters of the required length can be provided.

  The present invention provides a bonding force and peeling resistance with concrete or mortar placed later by the restraining effect of an ant-shaped cotter continuously formed in the longitudinal direction on the joint surface of concrete to be placed later. The force is large, and in particular, the shear resistance and peeling resistance of the concrete joint surface in the longitudinal direction (support span direction) of the precast concrete plate can be increased.

  Also, since the ant cotter is formed continuously in the longitudinal direction of the brecast concrete plate, it can be formed in parallel with the production of the brecast concrete plate in the production direction of the brecast concrete plate, Productivity is also very good.

  1 to 3 show an example of a precast concrete plate with a cotter according to the present invention. In the drawing, the upper surface of the precast concrete plate 1 formed into a rectangular plate shape having a predetermined width and length, that is, concrete to be post-cast. A plurality of ant-shaped cotters 4 are continuously formed in the longitudinal direction of the precast concrete plate 1 on the two joining surfaces 3.

  Further, a plurality of hollow holes 5 are continuously formed in the longitudinal direction in the cross section of the precast concrete plate 1 in order to reduce weight and save materials. In order to increase the bending resistance in the long direction (support span direction), prestress is introduced by inserting a plurality of tendons 6 in the long direction. Furthermore, a plurality of horizontal stripes 4a perpendicular to the longitudinal direction are formed on the top and bottom surfaces of the ant cotter 4 at predetermined intervals in the longitudinal direction.

  For example, as shown in FIG. 3 (b), the horizontal stripe 4a has a roller 7 having a plurality of tooth molds 7a on the surface, and the concrete is immediately applied to the surface of the concrete immediately after the ant cotter 4 is formed. It can be easily formed by pressing and rolling in the short direction before compaction.

  In such a configuration, the joining force and the peeling resistance force between the precast concrete plate 1 with a cotter and the concrete 2 post-cast to the upper surface (joining surface) 3 of the precast concrete plate 1 with the cotter are as follows. Due to the restraining effect, the shear resistance of the joining surface 3 in the longitudinal direction (support span direction) of the precast concrete plate with a cotter is sufficiently large.

  The ant-shaped cotter 4 is formed not only on the joint surface 3 on the upper surface of the precast concrete plate 1 but also on the joint surface 3 on the side surface that serves as a joint between the normal plates, and the joint is filled with concrete or mortar. For example, not only the out-of-plane direction of the plates but also the effect of transmitting the shearing force in the in-plane direction can be expected.

  FIG. 4 shows an example of a manufacturing method for continuously forming a precast concrete plate with an ant-shaped cotter as shown in FIG. 1 by moving a movable driving machine in the direction of an arrow on a long-line pallet bed. It is shown.

  In the figure, a convex pressing die 11 for forming a concave groove on the concrete 10 placed on the long-line pallet bed 9 from the concrete placing port 8 at the rear of the concrete placing port 8. A dovetail-shaped pressing die 12 is attached to form a concave groove formed by the pressing die 11 into an ant-shaped shape.

  The push die 12 is formed in the same rectangular cross section as the push die 11 on the traveling direction side, and gradually formed in a dovetail cross section toward the rear side. Further, the pressing dies 11 and 12 are attached on the same axis, and a plurality of the pressing dies 11 and 12 are attached at predetermined intervals in the width direction of the pallet bed 9.

  In such a configuration, the concrete slab is moved by moving the casting machine on the long line pallet bed 9 in the direction of the arrow while placing the concrete 10 on the pallet bed 9 from the concrete placing port 8. The ant-shaped cotter 4 is formed on the upper surface of the concrete slab by forming the convex dies 11 and the ant-like dies 12 back and forth together with the movable placement machine in the direction of the arrow. Is formed continuously in the longitudinal direction of the concrete plate.

  INDUSTRIAL APPLICABILITY The present invention has a sufficiently large joining force with concrete or mortar to be post-placed, and can be used for floor slabs of buildings such as apartments, warehouses, and offices.

An example of a precast concrete floor slab is shown, FIG. 1A is a partial plan view thereof, and FIG. It is an expanded sectional view which shows the joint surface of the precast concrete floor slab and the concrete cast | placed afterwards. (a) is a partial perspective view which shows an example of the precast concrete plate which has a horizontal stripe on a joining surface, (b) is sectional drawing which shows the jig for forming a horizontal stripe. It is sectional drawing which shows the manufacturing method of the precast concrete plate with a cotter by a mobile placement machine.

Explanation of symbols

1 Precast concrete plate 2 Post-cast concrete 3 Upper surface (post-cast concrete joint surface)
4 Ant-shaped cotter 4a Horizontal stripe 5 Hollow hole
6 Tensile material 7 Roller 7a Tooth mold 8 Concrete placement port 9 Long line pallet bed 10 Concrete 11 Convex mold 12 Ant-shaped mold

Claims (5)

  A precast concrete slab that is continuously formed in a longitudinal direction by a movable placement machine, cut to a predetermined length in the longitudinal direction, and forms a composite body integrated with the concrete to be post-molded. A precast concrete plate with a cotter, characterized in that ant-shaped cotters are continuously formed in the longitudinal direction on the joint surface of the concrete to be struck.   2. A precast concrete plate with a cotter according to claim 1, wherein a plurality of horizontal stripes intersecting with the ant-shaped cotter are formed on the joint surface of the concrete.   The precast concrete plate with a cotter according to claim 1 or 2, wherein a plurality of hollow holes are formed in the longitudinal direction.   The precast concrete plate with a cotter according to any one of claims 1 to 3, wherein prestress is introduced in the longitudinal direction.   A method for producing a precast concrete plate in which a concrete plate with a cotter having an ant-shaped cotter is continuously formed in the longitudinal direction on the joint surface of the concrete to be cast later, which is continuously cast by a mobile caster Before the concrete to be compacted, a convex pressing die is pressed against the upper surface of the concrete to form a concave groove, and further, an ant-shaped pressing die is pressed into the concave groove to form a dovetail groove. A method for producing a precast concrete plate with a cotter.

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