JPS63293277A - Inverted lining concrete construction method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a reverse-wound concrete method in which concrete is sequentially poured from the top to the bottom along the earth retaining wall surface.

(Prior art) In the reverse-rolling concrete method, it is difficult to bring the lower post-cast concrete into close contact with the upper pre-cast concrete because of the subsidence. Therefore, in most of the reverse winding construction methods to date, the method is to inject grout] after concrete hardens into the gap created at the joint (injection method), or to fill the gap with non-shrinkage mortar (filling method). ).

Both the injection method and the filling method for filling gaps in concrete joints are post-treatments that are carried out after concrete is poured.
This is a negative factor in terms of construction period, safety, and economy.

Furthermore, Japanese Patent Application Laid-Open No. 60-230434 discloses the following reverse-wound concrete construction method.

In the construction method of the same issue, as shown in Figure 3, a side formwork 22 is used to form a lower structure made of post-cast concrete below an upper structure 21 made of pre-cast concrete.
erected. An appropriate space is left between the upper edge of the side formwork 22 and the upper structure 21, and this space is used as a pouring opening 23 for post-cast concrete. A formwork 24 for pouring post-cast concrete is connected to this pouring opening 23 from the upper edge of the side formwork 22 diagonally upward. Then, the post-casting concrete is poured into the upper structure 21 through the pouring opening 23. At the same time, before the post-cast concrete 25 hardens, the post-cast concrete casting form 24 installed diagonally is erected almost vertically to close the casting opening 23.

According to this construction method, the post-cast concrete 25 is cured while the formwork 24 installed diagonally is left as is, and the jaws protruding from the formwork 240 are removed in the post-process after the formwork is removed. Compared to traditional construction methods, this method has the advantage of eliminating the need for the step of removing the jaw portion.

(Problems to be Solved by the Invention) In the conventional construction method shown in FIG. J: This has the effect of slightly compressing the concrete 25, and has the effect of improving the filling properties of the post-cast concrete 25. However, since the pouring opening 23 is very small compared to the size of the side formwork 22, the above-mentioned compression effect when it is closed with the formwork 24 is only slight.

Therefore, it was not effective enough to prevent the generation of gaps at the joints due to the sinking of the post-cast concrete 25.

Although not shown in FIG. 3, there is also a structure in which the bottom formwork defining the bottom of the post-cast concrete 25 and the side formwork 22 are connected, and the diagonal formwork 24 is connected to the top of the side formwork 22. Therefore, the number of connected parts of the formwork increases, which causes a decrease in work efficiency.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to provide a reverse-rolling concrete method that has good workability and allows post-cast concrete to adhere well to the underside of pre-cast concrete. It is on offer.

(Means for Solving the Problems) Therefore, in this invention, in the reverse roll concrete method in which concrete is poured sequentially from the top to the bottom along the earth retaining wall surface, the surface of the side formwork that is in contact with the poured concrete is A super-absorbent resin layer is attached, and first, a bottom formwork is fixed below the pre-cast concrete by protruding from the earth retaining wall like a shelf, and the side formwork is approximately attached to the front end of this bottom formwork. It is connected vertically, and in this state, the bottom formwork, earth retaining wall surface, side formwork,
Post-cast concrete was placed in the space surrounded by the underside of the pre-cast concrete.

(Function) According to the reverse-wound concrete construction method having the above configuration, moisture in the poured concrete is quickly absorbed by the superabsorbent resin layer of the side formwork. This resin layer absorbs a large amount of water and becomes gel-like, increasing its volume to hundreds of times its original volume. In other words, the thickness of the resin layer increases as water is absorbed, compensates for the volume reduction of the concrete on the side that loses water, and continues to press the concrete until it hardens. As a result, the post-cast concrete 1~ adheres well to the lower surface of the pre-cast concrete without any gaps.

(Example) FIGS. 1(A), (B), and (C) show each step of a reverse-wound concrete method according to an example of the present invention.

In the figure, 1 is an earth retaining wall installed in the vertical direction, and 2 is pre-cast concrete formed along the earth retaining wall 1 by this construction method. Below, the procedure for pouring post-cast concrete below this pre-cast concrete 2 will be explained.

A plurality of hanging reinforcing bars 3 are buried almost vertically in the concrete to be placed. Hanging reinforcing bars 3 in pre-cast concrete 2
Protrude downward as appropriate, and before placing the next stage of post-cast concrete, attach the suspension reinforcement bars 3 of the next stage to the suspension reinforcement bars 3 of the previous stage.
are sequentially connected using joints (not shown).

Also, I hit anchor bolt 4 on Sat rtBui! Embed them in advance according to the spacing. This anchor bolt 4 projects horizontally from the retaining wall 1, and its length is longer than the thickness of the concrete to be cast. anchor bolt 4
A thread is formed at the tip.

First, as shown in Fig. 1 (A), in order to place the second stage of concrete, at a predetermined position below the pre-cast concrete 2, a shelf protrudes diagonally upward from the retaining wall 1. The bottom formwork 5 is fixed to. This bottom formwork 5 is fixed to the suspension reinforcing bars 3 using fasteners 6. Next, pre-cast concrete 2
Reinforcing bars (not shown) are placed in the space between the bottom formwork 5 and the bottom formwork 5.

Next, as shown in FIG. 1(B), the side formwork 7 is joined to the upper surface of the front end of the bottom formwork 5, and the side formwork 7 is fixed using the anchor bolts 4. At a predetermined position of the side formwork 7, there is a hole (a hole slightly elongated in the vertical direction) through which the anchor bolt 4 passes, and the anchor bolt 4 projects to the front side of the side formwork 7 through this hole. Pass the backing plate 9 through the protruding side of the anchor bolt 4 and apply it to the side formwork 7, and then attach the fastener 10 to the threaded portion of the protruding end of the anchor bolt 4, as shown in Figure (B).
The side formwork 7 is fixed so that an appropriate distance is left between the pre-cast concrete 2 and the upper edge part of the side formwork 7.

A super-absorbent resin layer 70 is attached to the inner surface of the side formwork 7 that comes into contact with the poured concrete. An example of the structure of the super absorbent resin layer 70 is shown in detail in FIG.

As shown in FIG. 2, the superabsorbent resin layer 70 consists of a resin holder 71 made by holding superabsorbent resin powder on a low-density sheet-like carrier such as a nonwoven fabric, and a resin holder 71 with this resin holder 71 on the side. It consists of a cover 72 which is temporarily fixed to the surface of the formwork 7 and is placed over the surface of the formwork 7 and whose peripheral edge is fixed to the side formwork 7 so as to wrap it. This cover 72 is made of water-permeable and stretchable thin cloth or the like, allows water absorbed by the resin holder 71 to pass therethrough, and extends together with the resin holder 71 which expands upon absorbing water.

Now, in the state shown in Figure 1 (B), retaining wall 1 and bottom formwork 5
- Pour post-cast concrete in the space surrounded by the side formwork 7 and the lower surface of the pre-cast concrete 2.

In this case, the moisture in the post-cast concrete 12 is removed from the side formwork 7.
It is quickly absorbed into the super absorbent resin layer 70. ^ The water absorbent resin layer 70 absorbs a large amount of water and expands in volume, and the layer 70
increases in thickness. On the other hand, although the volume of the post-cast concrete 12 on the side that loses water decreases, the increase in the thickness of the resin layer 70 compensates for this, and the post-cast concrete 12 continues to be compressed. As a result, the eroded concrete 12 hardens in close contact with the lower surface of the pre-cast concrete 2 without causing any breathing.

(Effects of the Invention) As explained in detail above, in the reverse-wound concrete method according to the present invention, a superabsorbent resin layer is provided on the surface of the side formwork that comes into contact with the poured concrete. In addition to absorbing moisture, the volumetric expansion associated with water absorption continues to compress the concrete, so post-cast concrete adheres well to the underside of pre-cast concrete. Therefore, a high-quality reverse-wound concrete structure with no gaps in the joints can be realized, and troublesome post-processing is unnecessary.

[Brief explanation of drawings]

Figures 1 (A), (B), and (C) are diagrams showing each step of the reverse-wound concrete method according to an embodiment of the present invention, Figure 2 is a partial sectional view showing an example of the structure of a super absorbent resin layer, Figure 3 is a diagram showing the conventional reverse-rolling concrete construction method. 1...Earth retaining wall 2...Pre-cast concrete 3...
... Hanging iron stone 4 ... Anchor bolt 5 ... Bottom formwork 6 ...
...Fastener 7...Side formwork
9... Backing plate 10... Fastener 12... Post-cast concrete 70... Highly absorbent resin layer 71... Resin holding body 72...Cover patent applicant Obayashi Kumiyo Co., Ltd.
Patent Attorney - Kensuke Shiro
Patent Attorney Masatoshi Matsumoto Figure 1 (A) Figure 1 (B) Figure 1 (C) Figure 2 Figure 3

Claims (1)

[Claims] (1) In the reverse roll concrete method, in which concrete is poured sequentially from the top to the bottom along the earth retaining wall surface, a layer of highly water-absorbent resin is attached in advance to the surface of the side formwork that will be in contact with the poured concrete. , Fix the bottom form below the pre-cast concrete by protruding it like a shelf from the retaining wall, and connect the side form to the front end of this bottom form in a nearly vertical state. A reverse-rolling concrete method characterized by pouring post-cast concrete into the space surrounded by the frame, retaining walls, side formwork, and the underside of the pre-cast concrete.