JPH0696865B2 - Reverse winding concrete construction method - Google Patents

Description

[Detailed Description of the Invention] <Industrial application field> The present invention relates to a reverse-winding concrete construction method in which concrete is successively spliced from top to bottom along a retaining wall surface.

<< Conventional Technology >> In the reverse-rolling concrete method, it is difficult to bring the post-cast concrete below into close contact with the pre-cast concrete above. Therefore, in most reverse winding methods to date, either the method of injecting grout after concrete hardening into the gap formed in the joint (injection method) or the method of filling non-shrink mortar into the above gap (filling method) I was dealing with either.

Both the injection method and the filling method for filling the gaps in the splice part are post-treatments performed after concrete is poured,
It is a negative factor in terms of construction period, safety, and economic efficiency.

Further, JP-A-60-230434 discloses the following reverse winding concrete construction method.

In the construction method of the same report, as shown in FIG. 3, a side formwork 22 for forming a lower structure made of post-cast concrete is formed below the upper structure 21 made of precast concrete. An appropriate gap is left between the upper edge of the side formwork 22 and the upper structure 21, and the post-casting concrete pouring opening is placed there.
23. A post-casting concrete pouring formwork 24 is connected to the pouring port 23 from the upper edge of the side formwork 22 obliquely upward.

Then, the post-casting concrete is cast through the casting port 23 below the upper structure 21, and the post-casting concrete casting formwork 24 that is diagonally installed before the post-casting concrete 25 hardens is almost vertical. It stands upright and closes the pouring port 23.

According to this construction method, the diagonally installed formwork 24 is left as it is, the post-cast concrete 25 is hardened, and the jaw portion protruding to the part of the formwork 24 is removed in a post process after the formwork is removed. As compared with the conventional construction method, there is an advantage that the step of deleting the jaw portion becomes unnecessary.

<< Problems to be Solved by the Invention >> In the conventional construction method shown in FIG. 3, the upper construction is carried out in a process in which it is installed diagonally and the mold 24 is raised almost vertically.
There is an effect that the post-cast concrete 25 below 21 is slightly pressed, and this has the effect of improving the filling property of the post-cast concrete 25. However, since the pouring port 23 is very small compared to the size of the side form 22, the above-mentioned compression effect when closing it with the form 24 is only slight. Therefore, it was not effective enough to prevent the generation of gaps in the joints due to the subsidence of the post-cast concrete 25.

Although not shown in FIG. 3, the post-cast concrete 25
The side form 22 and the side form 22 that define the bottom of the
Since the oblique formwork 24 is connected to the upper part of the mold, the connection part of the formwork is increased, which is a cause of lowering workability.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to have good workability, and to make the post-cast concrete adhere well to the lower surface of the pre-cast concrete to facilitate their integration. It is to provide a reverse winding concrete construction method that is made possible.

<< Means for Solving Problems >> Therefore, in the present invention, in the reverse-winding concrete construction method in which the concrete is successively spliced from the upper side to the lower side along the soil retaining wall surface, in the case of the post-cast concrete to be mounted below the precast concrete. The formwork is provided with a highly water-absorbent resin layer on the surface in contact with the concrete that is placed in the formwork, and the concrete is placed in the formwork and swells the superabsorbent resin layer by the water in the concrete, As a result, the post-cast concrete is placed while pressing the concrete in the formwork.

<< Operation >> According to the reverse-winding concrete construction method having the above configuration, the water in the placed concrete is promptly absorbed by the superabsorbent resin layer of the side mold. This resin layer absorbs a large amount of water and becomes a gel, and its volume is hundreds of times that before water absorption. That is, the thickness of the resin layer increases with water absorption,
Make up for the volume loss of concrete on the side that loses water, and continue to apply pressure until the post-cast concrete hardens. As a result, the post-cast concrete adheres well to the lower surface of the above-mentioned pre-cast concrete without any gaps.

<< Example >> FIGS. 1 (A), (B) and (C) show respective steps of a reverse winding concrete construction method according to an example of the present invention.

In the figure, 1 is an earth retaining wall provided in a vertical direction, and 2 is a precast concrete formed along the earth retaining wall 1 by this method. In the following, a procedure for splicing the post-cast concrete below the pre-cast concrete 2 will be described.

Plural suspension reinforcing bars 3 are embedded almost vertically in the concrete to be poured. Suspended rebar 3 in precast concrete 2
Are appropriately projected downward, and before the post-casting concrete of the next stage is placed, the suspension bar 3 of the next stage is attached to the suspension bar 3 of the next stage.
Are sequentially connected by joints (not shown).

Further, the anchor bolts 4 are embedded in the earth retaining wall 1 in advance so as to correspond to the splicing intervals. The anchor bolt 4 projects horizontally from the earth retaining wall 1 and its length is longer than the thickness of the concrete to be placed. A screw is formed at the tip of the anchor bolt 4.

First, as shown in FIG. 1 (A), in order to drive the second-stage concrete, at a predetermined position below the precast concrete 2, the bottom is protruded diagonally upward from the retaining wall 1 into a shelf plate shape. Fix the formwork 5. The bottom formwork 5 is fixed to the suspension bars 3 by using fasteners 6. Next, precast concrete 2
A reinforcing bar (not shown) is arranged in the space between the bottom mold 5 and the bottom mold 5.

Next, as shown in FIG. 1 (B), a side form 7 is joined to the upper surface of the front end of the bottom form 5, and the side form 7 is fixed using the anchor bolt 4. A hole (a slightly long hole in the vertical direction) through which the anchor bolt 4 is inserted is provided at a predetermined position of the side frame 7, and the anchor bolt 4 projects to the front side of the side frame 7 through this hole. Apply the pad plate 9 to the protruding side of the anchor bolt 4 and apply it to the side frame 7, and further attach the fastener 10 to the threaded portion of the protruding end of the anchor bolt 4, and as shown in FIG. The side mold 7 is fixed so that there is an appropriate space between the mold 7 and the upper edge portion.

A super water-absorbent resin layer 70 is attached to the inner surface of the side mold 7 which contacts the cast concrete. This super absorbent resin layer
An example of the configuration of the portion 70 is shown in detail in FIG.

As shown in FIG. 2, the highly water-absorbent resin layer 70 includes a resin holder 71 made by holding a powder of the highly water-absorbent resin on a sheet carrier having a low density such as a non-woven fabric, and the resin holder 71. Formwork 7
It is composed of a cover 72, which is temporarily fixed to the surface of, and is covered, and the peripheral edge is fixed to the side frame 7 so as to wrap it. This cover 72 is made of water-permeable and elastic thin cloth etc.,
It absorbs water absorbed by the resin holder 71, and extends along with the resin holder 71 that swells by absorbing water.

Now, in the state of FIG. 1 (B), the retaining wall 1 and the bottom mold 5
・ Post-cast concrete is placed in the space surrounded by the side formwork 7 and the lower surface of the precast concrete 2.

In this case, the water in the post-cast concrete 12 is quickly absorbed by the superabsorbent resin layer 70 of the side form 7. The super absorbent resin layer 70 absorbs a large amount of water and expands in volume, and the thickness of the layer 70 increases. On the other hand, the volume of the post-cast concrete 12 on the side that loses water decreases, but the increase in the thickness of the resin layer 70 compensates for this.
The post-cast concrete 12, which is not yet solidified, continues to be pressed. As a result, the post-cast concrete 12 is solidified in a state of being in close contact with the lower surface of the pre-cast concrete 2 and integrated with the pre-cast concrete.

<Effects of the Invention> As described in detail above, according to the present invention, in the reverse winding concrete construction method, by compressing the post-cast concrete in the form by swelling of the superabsorbent resin layer,
The splicing portion between the precast concrete and the postcasting concrete is easily adhered to prevent a gap from being generated between them, whereby the post-treatment of the striking joint portion is unnecessary, High-quality reverse-wound concrete in which precast concrete and postcast concrete are integrated can be easily constructed.

[Brief description of drawings]

1 (A), (B) and (C) are diagrams showing respective steps of a reverse winding concrete construction method according to an embodiment of the present invention, and FIG. 2 is a partial sectional view showing a constitutional example of a super absorbent resin layer, FIG. 3 is a view showing a conventional reverse winding concrete construction method. 1 …… Soil retaining wall 2 …… Precast concrete 3 …… Suspended rebars 4 …… Anchor bolts 5 …… Bottom formwork, 6 …… Fasteners 7 …… Side formwork, 9 …… Attach plate 10 …… Fastening Tool 12 …… Post-cast concrete 70 …… Super absorbent resin layer 71 …… Resin holder, 72 …… Cover

Claims (1)

[Claims] 1. A reverse winding concrete construction method in which concrete is successively spliced from top to bottom along a retaining wall surface,
The form of the post-cast concrete that is installed below the pre-cast concrete is provided with a super absorbent resin layer on the surface in contact with the concrete that is cast in the form, and the concrete is placed in the form and A reverse-winding concrete construction method characterized in that the superabsorbent resin layer is swollen by water, and the post-cast concrete is placed while pressing the concrete in the formwork by this.