JPS62253821A - Construction of concrete floor slab - Google Patents

Abstract

PURPOSE:To simplify operations by a method in which the ground where floor slab is to be constructed is excavated, leveling concrete is placed, reinforcing bars are set through a separation layer and concrete is plated on the leveling concrete and hardened, and the ground below the concrete is excavated. CONSTITUTION:In constructing a concrete floor slab 3 for building the underground first floor of a structure under the ground 1, the ground 1 is excavated down to about 50mm from the bottom 3a of the floor slab 3. Leveling concrete 4 is then placed in a thickness of about 50mm on the surface of the excavated ground 1a and hardened, and a synthetic resin sheet 5 is laid on it. Reinforcing bars are set at an adequate interval on the sheet 5 and concrete 7 for floor slab is placed on the sheet 5 and hardened. While removing the concrete 4 and the sheet 5, the ground 1 below the concrete 7 is excavated.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for constructing a concrete floor slab constituting a basement floor of a concrete structure such as a reinforced concrete structure or a steel-frame reinforced concrete structure.

``Prior Art'' Conventionally, as a method for constructing concrete slabs that constitute the basement floors of reinforced concrete structures and steel-framed reinforced concrete structures, the ground on which the structure will be built is covered with the foundation of the structure in advance. After cutting the roots to the lowest part of the construction and building the foundation there, the reinforcing bars for the columns and beams are framed on this foundation, and the reinforcement for the floor slab (floor slab) that extends between the beams is arranged. A commonly used method is to construct a concrete formwork, pour concrete, remove the formwork after the concrete has hardened, and construct a floor slab.

"Problems to be Solved by the Invention" By the way, in the above method, the ground is first cut down to the foundation of the structure, and then the structure is constructed sequentially upward from the foundation, so to speak. , it is no different from building a structure on the ground. Therefore,
For example, in order to arrange reinforcing bars, it was necessary to separately set up a temporary work floor using means such as suspended scaffolding.

Therefore, in order to reduce the incidental work that requires a large amount of man-hours, it is ideal from the viewpoint of ensuring safety and work efficiency that the work floor, that is, the ground, is always located at the feet of the workers. One of the methods implemented from the viewpoint of form, etc. is called the reverse concrete method. This method is the opposite of the above method, in that concrete is poured from the upper floor of the basement to the lower floor.

However, even with this method, in order to pour concrete, the formwork must be suspended from steel beams on the upper floor, or shoring to support the formwork must be installed on the root cutting surface. However, it still required laborious work.

Therefore, the present invention aims to simplify reinforcement and form work as much as possible when constructing concrete slabs that constitute the basement floors of concrete structures such as reinforced concrete structures and steel-framed reinforced concrete structures, thereby achieving safe construction. The purpose is to provide a method.

"Means for Solving the Problems" Therefore, in the present invention, in order to achieve the above object, the concrete slab constituting the basement floor of a concrete structure is constructed by the reverse concrete construction method, and Cut the surface to a depth that is further down by a dimension L from the bottom of the concrete slab to be constructed,
After pouring sacrificial concrete to a thickness L on the cut surface, a separation layer from the concrete is placed on the sacrificial concrete, and reinforcement for the floor slab and concrete pouring are placed on the separation layer. After the concrete had hardened, the lower part of the concrete was root-cut while removing the sacrificial concrete.

Note that the separation layer can be easily and effectively applied by using a synthetic resin sheet or the like.

``Operation'' By cutting the ground slightly deeper than the bottom of the target concrete slab and pouring concrete on the surface of the cut, this concrete can be used as the formwork for the concrete slab to be constructed. It can be used as

Furthermore, reinforcement work can be carried out extremely easily by using this waste concrete.

In general, a synthetic resin sheet interposed between the waste concrete and the concrete for the floor slab cast on the waste concrete has a predetermined hardness to the poured concrete. When removing the concrete,
It acts as a so-called mold release agent.

``Example'' An example of the present invention will be described below with reference to FIGS. 1 and 2. These figures show the present invention applied to a reinforced concrete structure.

In the figure, what is indicated by the symbol l is the ground that forms the so-called ground surface. In the ground l, a side wall 2 constituting the basement of the structure is formed as an underground wall.

The following procedure may be used to construct the concrete slab 3 forming the floor constituting the first basement floor of this structure.

First, the ground l is excavated (root cut) to a position 5°mff1 lower than the depth at which the bottom surface 3a of the concrete slab 3 to be constructed is located.

Next, after leveling the root cutting surface 1a to some extent,
Directly pour the sacrificial concrete 4 onto the root cutting surface la.
The concrete is poured to a thickness of 0 mm, and the surface is evenly leveled with a wooden trowel. The upper surface of this sacrificial concrete 4 will be the position where the bottom surface 3a of the concrete floor slab 3 to be constructed later will be formed.

Once the sacrificial concrete 4 has hardened, a synthetic resin sheet such as a polyethylene sheet 5 is uniformly laid on the sacrificial concrete 4.

At this time, the polyethylene sheet 5 is stretched as much as possible and fixed with tape or the like.

Once the polyethylene sheet 5 has been applied to the sacrificial concrete 4 as described above, the final reinforcing bars 6 constituting the concrete slab 3 are then placed on the polyethylene sheet 5. At this time, instead of placing the reinforcing bars 6 flat on the polyethylene sheet 1-5, the reinforcing bars 6 are placed entirely on the polyethylene sheet by, for example, providing downwardly protruding legs on the reinforcing bars 6 at intervals. An appropriate interval is provided between the sheet 5 and the sheet 5.

Once the predetermined reinforcing bars 6 have been arranged, concrete 7 for the floor slab is poured directly onto the polyethylene sheet 5 on which the reinforcing bars 6 have been arranged.

Here, the sacrificial concrete 4 cast on the ground 1 is uniformly formed in the lower part of the concrete 7 through the polyethylene sheet 5, so that the sacrificial concrete 4 is , which acts as a formwork for the concrete 7 for the floor slab. Once concrete 7 has been poured, its surface is leveled. The upper surface of this concrete 7 forms the upper surface of the intended concrete floor slab 3.

Then, when the poured concrete 7 hardens to a predetermined concrete strength, the ground l below the concrete 7 for the floor plate is excavated.

As a result, the desired concrete floor slab 3 is formed. At this time, the surface concrete 4 and polyethylene sheet 5 located directly below the concrete 7 are also removed at the same time. Here, since the polyethylene sheet 5 is interposed between the sacrificial concrete 4 and the concrete 7 for the floor slab, it acts as a so-called mold release agent, and removes the sacrificial concrete 4 from the concrete 7. The work is extremely easy to do. The root cutting at the bottom of the concrete slab 3 is the concrete slab (
(not shown), the height should be 50 mm lower than the position where the bottom of the intended concrete slab will be formed, so that the same method as above for constructing the concrete slab 3 for the first basement floor can be used. This is done to the greatest depth.

Thereafter, in the same manner as above, concrete was poured uniformly to a thickness of 50 mm on the surface of the root cut, a polyethylene sheet was placed on top of it, and reinforcement for the deck slab and concrete were placed on this polyethylene sheet. After the concrete for the floor slab has hardened, the lower part of the concrete for the floor slab is cut while removing the waste concrete and the polyethylene sheet.
All you have to do is construct the concrete floor slab for the floor...

In addition, in this example, the depth of root cutting beyond the position where the bottom surface of the deck slab to be constructed is formed is 5.
0 mm, and 50 mm thick sacrificial concrete is placed there. This is because when pouring the concrete 7 that forms the floor slab, the sacrificial concrete 4 acts as a formwork for the concrete 7. This was done from the standpoint that these dimensions are both necessary and sufficient. However, this dimension
The dimension is not limited to m, but may be set to the most efficient dimension depending on, for example, the geology of the ground 1 and the thickness of the concrete slab 3 to be constructed.

``Effect of the invention 1 As explained above, according to the present invention, a root cut is made in the ground surface slightly deeper than the bottom position of the concrete slab to be constructed, and dumping concrete is poured on the surface of the root cut. By doing so, this waste concrete can be used as formwork for pouring the concrete that will form the concrete slab to be constructed, so it can be hung from the beams on the upper floor or installed with shoring. There is no need to set up conventional formwork.Furthermore, since reinforcement work can be done using this waste concrete, temporary work floors such as suspended scaffolding can be used for reinforcement work. In this way, when constructing the concrete slab that makes up the basement floor of a concrete structure, the reinforcement and formwork work is simplified as much as possible, and it has excellent effects such as increasing safety. play.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention,
FIG. 1 is a side sectional view, and FIG. 2 is an enlarged view of a portion surrounded by a dashed line in FIG. 1. 1... Ground, 1a... Root cutting surface, 3... Concrete slab, 3a...
...Bottom, 4...Discarded concrete,
5...Polyethylene sheet, 6...
・Reinforced steel, 7... Concrete.

Claims (1)

[Scope of Claims] 1. A method for constructing a concrete floor slab constituting a basement floor of a concrete structure by a reverse concrete construction method, wherein the ground surface is a concrete floor to be constructed. Further dimension L from the bottom of the plate
After cutting the root to a depth that is lower than the root cut, and pouring concrete to a thickness of L on the surface of the cut, a separation layer from the concrete is applied on top of the concrete, and on the separation layer, A concrete floor characterized in that a concrete floor slab is formed by arranging reinforcement for the floor slab and placing concrete, and after the concrete hardens, cutting the lower part of the concrete while removing the waste concrete. How to build an edition. 2. The method for constructing a concrete slab according to claim 1, wherein a synthetic resin sheet is used as the means for applying the separation layer.