JP7300231B1 - Construction method of precast floor slab, waterproof layer and floor slab - Google Patents

Abstract

[PROBLEMS] To propose a precast floor slab and a waterproof layer capable of forming a waterproof layer having a certain quality without forming weak portions, and to propose a floor slab using the precast floor slab or the waterproof layer. We propose a construction method for A precast floor slab 2 constituting a bridge floor slab 1 is connected to another adjacent precast floor slab 2 via a joint part 3, and the main body part 4 is mainly made of hardened concrete. and a waterproof layer 5 laminated on the upper surface of the main body 4 and made of a hardened fiber-reinforced cement-based material impermeable to water. The planar shape of the tip of the waterproof layer 5 on the side of the joint portion 3 presents a corrugated shape in which curved peak portions and curved valley portions are combined. [Selection drawing] Fig. 2

Description

TECHNICAL FIELD The present invention relates to a precast floor slab and a waterproof layer having a waterproof function, and a construction method for the precast floor slab or the floor slab provided with the waterproof layer.

In the construction of bridges, factory-produced precast floor slabs may be used to save labor and reduce costs. In particular, in road bridge repair work (floor slab replacement work), there is a demand for shortening the construction period and early opening of roads by using precast floor slabs.

In general, a waterproof layer is formed on the upper surface of the floor slab of a bridge in order to prevent deterioration due to permeation of rainwater and the like. For example, Patent Literature 1 discloses a precast floor slab on which a waterproof layer made of hardened compact ultra-high-strength fiber-reinforced concrete is formed on the upper surface.

The waterproof layer of the precast floor slab of Patent Document 1 has a wedge-shaped protruding portion at the end facing the joint between the precast floor slabs. Adhesion is improved and shear resistance can be obtained.

Japanese Patent Application Laid-Open No. 2021-143486

The end of the waterproof layer of the precast floor slab of Patent Document 1 has a wedge shape that tapers toward the tip (joint part side), so fibers are less likely to wrap around the tip, and the properties of the waterproof layer change. There is a risk. That is, at the tip portion of the protruding portion, the cross-linking effect of the fiber cannot be expected, and there is a possibility that the yield strength is reduced.

From this point of view, the present invention proposes a precast floor slab and a waterproof layer capable of forming a waterproof layer having a certain quality without forming weak points, and the precast floor slab or waterproof layer. The object is to propose a construction method for floor slabs using a waterproof layer.

The present invention for solving the above-mentioned problems is a precast floor slab that constitutes a floor slab of a bridge by being connected in the direction of the bridge axis or in the direction transverse to the bridge axis and connected to each other via joints. It consists of a main body mainly composed of a hardened body, and a waterproof layer made of a hardened body of water-impermeable fiber-reinforced cement-based material laminated on the upper surface of the main body. An end portion of the waterproof layer on the side of the joint portion has a plurality of steps that are lower than the upper step and protrude toward the joint portion, and a flat surface of a tip of the waterproof layer on the side of the joint portion. The shape presents a wavy shape combining curved peaks and curved valleys.

In such precast floor slabs, the ends of the waterproof layer exhibit a curved wave shape, so the fibers are spread over the ends on the joint side as well. Therefore, it is possible to expect a cross-linking effect by the fibers, and it is possible to ensure the same performance in the end portion as in the other portions. That is, since the waterproof layer has the same quality as a whole, it is possible to suppress the deterioration of the waterproof property caused by the damage due to the concentration of stress.

In addition, since the end portion of the waterproof layer on the side of the joint portion has a plurality of steps that are lower than the upper step and protrude toward the joint portion, water such as rainwater is prevented from entering the boundary portion of the joint portion. Even if water permeates, the permeated water stays in the horizontal portion of the stepped portion, so that the permeation of water to the main body portion can be prevented.

The tips of the stepped portions are preferably parallel. By doing so, the area of the joint portion of the waterproof layer can be minimized. Therefore, by reducing the amount of cement-based material to be placed in the joint portion, labor for construction can be reduced. In addition, it is possible to prevent the shape of the formwork for forming the waterproof layer from becoming complicated, and to reduce the time and effort of producing the formwork.

Further, the interval between the bottoms of the adjacent trough portions forming the wave pattern is larger than the interval between the tips of each step, and is larger than the height from the bottom of the trough portion to the top of the crest portion. is desirable. By doing so, the fibers can more reliably wrap around to the tip portion, and deterioration of the quality at the end portion of the waterproof layer can be suppressed.

Construction of floor slabs using such precast floor slabs includes the steps of laying the precast floor slabs and placing filling concrete in the gaps between the precast floor slabs and other adjacent precast floor slabs. and placing a fiber-reinforced cementitious material having the same material as that of the waterproof layer in the space surrounded by the upper surface of the interfill concrete and the edge of the waterproof layer.

The waterproof layer of the present invention consists of a hardened body of a fiber-reinforced cement-based material impermeable to water placed on the upper surface of the floor slab, and is provided at the end of the floor slab facing the joint section below the upper step. The step has a plurality of steps protruding toward the joint portion, and the plane shape of the tip of the floor slab on the joint portion side is a corrugated shape combining curved peaks and curved valleys. presenting.

Since the end of the waterproof layer exhibits a curved wavy shape, the fiber is formed in a state where the fiber is spread over the end on the joint side. Therefore, it is possible to expect a cross-linking effect by the fibers, and it is possible to ensure the same performance in the end portion as in the other portions. That is, since the waterproof layer has the same quality as a whole, it is possible to suppress the deterioration of the waterproof property caused by the damage due to the concentration of stress.

Construction of a floor slab having such a waterproof layer includes a step of laying a precast floor slab, a step of forming the waterproof layer, and filling a gap between the precast floor slab and another adjacent precast floor slab. A step of placing concrete, and a fiber having the same composition as the fiber-reinforced cementitious material constituting the waterproof layer in the space surrounded by the upper surface of the interstitial concrete and the edge of the waterproof layer of the adjacent precast floor slab. and a step of placing a reinforcing cementitious material.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to form a waterproof layer with a certain quality on the upper surface of a floor slab without forming a weak part.

It is a cross-sectional view showing a floor slab according to the first embodiment. It is a perspective view showing the precast floor slab of the first embodiment. FIG. 4 is a plan view showing an example of a tip portion of a waterproof layer; FIG. 2 is a cross-sectional view showing the procedure of the floor slab construction method of the first embodiment, in which (a) is a precast floor slab laying state, (b) a filling concrete placement state, and (c) a fiber reinforced cement-based material placement state. It is the setting situation. (a) is a photograph of the end portion of the waterproof layer of this embodiment, and (b) is a photograph of the end portion of the waterproof layer of the comparative example. It is a cross-sectional view showing a floor slab according to a second embodiment. FIG. 4 is a perspective view showing the procedure of the floor slab construction method of the second embodiment, in which (a) is a precast floor slab laying state, and (b) is a form assembly state. FIG. 8 is a cross-sectional view showing the procedure of the floor slab construction method following FIG. 7, in which (a) is the construction status of the waterproof layer, (b) is the construction status after the formwork is removed, and (c) is the construction status of the joint.

<First embodiment>
In the first embodiment, a case of constructing a bridge using precast floor slabs will be described. The floor slab constitutes a part of the upper structure, and is laid across the abutments and piers that are the lower structure. In this embodiment, as shown in FIG. 1, a floor slab 1 is formed by connecting a plurality of precast floor slabs 2, 2, . . . Adjacent precast floor slabs 2 are connected to each other via joint portions 3 .

The precast floor slab 2 is composed of a main body 4 and a waterproof layer 5 laminated on the upper surface of the main body 4, as shown in FIG. The main body 4 is a concrete hardened body having a rectangular shape in plan view. The main body part 4 is formed by placing the necessary reinforcing bars inside and placing concrete in a formwork in which tendons are arranged, and introducing prestress through the tendons after the concrete hardens. A so-called PCa precast floor slab was formed.

The waterproof layer 5 is made of a hardened fiber-reinforced cement-based material impermeable to water. The fiber-reinforced cement-based material that constitutes the waterproof layer 5 is placed over the upper surface of the concrete that was placed when forming the main body 4 before the concrete hardened. Therefore, the main body part 4 and the waterproof layer 5 are integrally joined together, and when prestress is applied to the main body part 4 , the prestress is also applied to the waterproof layer 5 .

At the tip of the waterproof layer 5 on the side of the joint portion 3 , a stepped portion of two steps, the lower step of which protrudes toward the joint portion 3 side, is formed. Although the height of each step is not limited, it is set to 10 mm as an example in this embodiment. That is, the waterproof layer 5 of this embodiment has a thickness of 20 mm.

The tip edges of the upper and lower steps of the stepped portion formed at the tip of the waterproof layer 5 are parallel, and the planar shape thereof exhibits a wavy shape combining curved peaks and curved valleys. The interval D2 (for example, 30 cm) between the bottoms of the adjacent valleys forming the corrugation is larger than the interval D3 (for example, 3 cm) between the tops of the steps. Also, the distance D2 between the bottoms of the adjacent valleys forming the corrugation is greater than the height D1 (for example, 3 cm) from the bottom of the valleys to the top of the peaks (see FIG. 3).

It should be noted that in the distance D1 from the top of a peak portion to the bottom of a valley portion and the distance D2 from the bottom of a valley portion to the bottom of the next valley portion, the corrugation is such that D1≦D2. preferable. That is, it is preferable that the aspect ratio of the distance D1 and the distance D2 is such that the distance D2 is larger than the aspect ratio of 1:1. By setting the relationship between the distance D1 and the distance D2 in this manner, the fibers to be mixed as a material easily wrap around the tip of the waterproof layer 5 and are easily dispersed evenly. The aspect ratio is 1:1.1 or more, 1:1.2 or more, 1:1.3 or more, 1:1.4 or more, 1:1.5 or more, 1:1.6 or more, 1:1. It is preferable that the ratio is 7 or more, 1:1.8 or more, or 1:1.9 or more. Furthermore, it is more preferable when it is 1:2 or more.

To construct the floor slab 1 using the precast floor slab 2, first, as shown in FIG. 4(a), the precast floor slab 2 is laid next to the previously laid precast floor slab 2 (laying step). . At this time, reinforcing bars are arranged at joint portions 3 of adjacent precast floor slabs 2 as necessary.

Next, as shown in FIG. 4(b), filling concrete 6 is placed in the gap between the adjacent precast floor slabs 2 (filling concrete placing step).
After placing the interfilling concrete 6, as shown in FIG. A fiber reinforced cementitious material 7 having the same material as is placed.

According to the precast floor slab 2, since the end portion of the waterproof layer 5 exhibits a curvilinear wave shape, the fibers also spread over the end portion on the joint portion 3 side. Therefore, it is possible to expect a cross-linking effect by the fibers, and it is possible to ensure the same performance in the end portion as in the other portions. Therefore, since the waterproof layer 5 has the same quality as a whole, it is possible to suppress the deterioration of the waterproofness of the floor slab 1 due to the damage caused by the concentration of stress. In addition, the interval between the bottoms of adjacent troughs constituting the corrugation is larger than the interval between the tops of each step and is larger than the height from the bottom of the troughs to the top of the crests. , the fibers can more reliably wrap around to the tip portion, and deterioration of the quality at the end portion of the waterproof layer 5 can be suppressed.

Here, FIG. 5(a) is a photograph of the cross section of the tip portion of the waterproof layer 5 of the present embodiment. Moreover, FIG.5(b) is the photograph which image|photographed the cross section when the front-end|tip part of the waterproof layer 5 was made into a triangular corrugated shape as a comparative example. As shown in FIG. 5( a ), it was confirmed that the fibers were spread over the edges of the waterproof layer 5 by making the tip of the waterproof layer 5 curved and wavy. On the other hand, in the case of a triangular corrugated shape (a shape that tapers toward the tip), as shown in FIG. 5(b), it was confirmed that the fibers did not reach the tip. Here, the fibers appear as white lines in FIGS.

Moreover, since the end portion of the waterproof layer 5 exhibits a curved corrugated shape, stress is prevented from concentrating on one point. That is, when the planar shape of the end of the waterproof layer 5 is a corrugated shape with corners (for example, a shape in which triangles are continuous), stress is concentrated at the tip of the corner, which may cause breakage. Curvilinear corrugations distribute stress and do not create weak points.

By making the end portion of the waterproof layer 5 corrugated, the bondability between the waterproof layer 5 and the fiber-reinforced cement-based material placed in the joint portion 3 is high. That is, by engaging the end of the waterproof layer 5 and the joint portion 3, it is possible to resist displacement in the lateral direction and maintain the waterproof property.

In addition, since the end of the waterproof layer 5 on the side of the joint part 3 has a step, even if water such as rainwater penetrates from the boundary part (joint) of the joint part 3, the horizontal part of the step part Since the water permeated into the body part 4 is retained, water can be prevented from permeating to the main body part 4. - 特許庁

In addition, by making the tip of the step portion parallel, the area of the splicing portion of the waterproof layer 5 can be minimized. Therefore, by reducing the amount of the cement-based material to be placed in the joint portion 3, labor for construction can be reduced. In addition, it is possible to prevent the shape of the formwork from becoming complicated when forming the waterproof layer 5, and to reduce the time and effort of producing the formwork.

<Second embodiment>
In the second embodiment, a case will be described in which the waterproof layer 5 is formed on the upper surface of the existing precast floor slab 8 (see FIG. 6). The waterproof layer 5 is formed by placing a water-impermeable fiber-reinforced cementitious material 7 on the upper surface of a precast floor slab 8 laid in advance. The waterproof layer 5 presents a corrugated shape in which curved peaks and curved valleys are combined at the ends facing the joints 3 of the precast floor slabs 8 .

A construction method of the floor slab of the second embodiment will be described. First, as shown in FIG. 7(a), a precast floor slab 8 is laid (laying step). Next, as shown in FIG. 7(b), on the precast floor slab 8, the formwork 9 for the waterproof layer 5 is installed (assembled). The mold 9 facing the joint part 3 is formed with a step corresponding to the step of the waterproof layer 5 so that the upper side protrudes more than the lower side.

After the formwork 9 is installed, a fiber-reinforced cementitious material 7 is cast into the formwork 9 to form a waterproof layer 5, as shown in FIG. 8(a). When the fiber-reinforced cementitious material 7 develops a predetermined strength, the mold 9 is removed as shown in FIG. 8(b). Then, as shown in FIG. 8(c), the fiber-reinforced cementitious material 7 is placed in the joint portion 3 (the gap between the adjacent precast floor slabs 8 and the gap between the adjacent waterproof layers 5) to form a floor slab. 1 is formed.

According to the floor slab construction method of the second embodiment, even if the precast floor slab 8 without the waterproof layer 5 is used, the floor slab 1 with excellent waterproofness can be formed. Further, according to the floor slab construction method of the second embodiment, it is possible to form the waterproof layer 5 (floor slab 1) having the same performance as the floor slab construction method of the first embodiment.

The embodiments according to the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and each of the above-described constituent elements can be modified as appropriate without departing from the gist of the present invention.

For example, in the above-described embodiment, the waterproof layer 5 has two steps at the end, but the number of steps formed at the end of the waterproof layer 5 is not limited, and may be three or more. may Moreover, it is not always necessary to form a step at the end of the waterproof layer 5 .

Moreover, in the above-described embodiment, the case where the tip of each step formed at the end of the waterproof layer 5 is parallel has been described, but the shape of the tip edge of each step may be different. That is, the edge portion of the lower stage may be corrugated and the edge portion of the upper stage may be linear. In addition, although the tops of the upper and lower peaks are illustrated as aligned on the same straight line, the tops may not be aligned on the same straight line and may be displaced from each other.

The thickness of the waterproof layer 5 is not limited to 20 mm, and may be determined as appropriate. Further, the shape of the corrugated portion at the tip of the waterproof layer 5 (the radius of the curved portion forming the corrugated shape, the width and height of the peaks and valleys) is not limited and may be determined as appropriate.

In the above embodiment, the precast floor slab 2 is used, but the waterproof layer 5 may be formed by placing a fiber-reinforced cementitious material 7 on the upper surface of an existing floor slab. At this time, the end facing the joint (joint portion 3) of the waterproof layer 5 is corrugated.

REFERENCE SIGNS LIST 1 floor slab 2 precast floor slab 3 joint portion 4 body portion 5 waterproof layer 6 filling concrete 7 fiber reinforced cement-based material 8 precast floor slab

Claims (6)

Precast floor slabs that are connected in a bridge axial direction or a bridge transverse direction and constitute a bridge floor slab by connecting to each other via joints,
a main body mainly composed of hardened concrete;
a waterproof layer made of a hardened water-impermeable fiber-reinforced cementitious material laminated on the upper surface of the main body,
An end portion of the waterproof layer on the side of the joint portion has a plurality of steps that are lower than the upper step and protrude toward the joint portion,
A precast floor slab, wherein the planar shape of the tip of the waterproof layer on the side of the joint portion presents a corrugated shape combining curved peaks and curved valleys. A precast floor slab according to claim 1 , characterized in that the top edges of each step are parallel. The distance between the bottoms of the adjacent troughs forming the corrugation is greater than the distance between the tips of each step, and is greater than the height from the bottom of the troughs to the top of the peaks. A precast floor slab according to claim 2 . Consists of hardened water-impermeable fiber-reinforced cement-based material cast on the upper surface of the floor slab,
The end of the floor slab facing the joint portion has a plurality of steps that are lower than the upper step and protrude toward the joint portion, and the planar shape of the tip of the floor slab on the joint portion side. A waterproof layer characterized by exhibiting a wavy shape in which curved peaks and curved valleys are combined. A step of laying the precast floor slab according to any one of claims 1 to 3 ;
placing filling concrete in the gap between the precast floor slab and another adjacent precast floor slab;
and a step of placing a fiber-reinforced cementitious material having a material equivalent to that of the waterproof layer in a space surrounded by the upper surface of the interstitial concrete and the end of the waterproof layer. and the construction method of the floor slab. A step of forming the waterproof layer according to claim 4 on the upper surface of the existing precast floor slab;
placing filling concrete in the gap between the precast floor slab and another adjacent precast floor slab;
A fiber-reinforced cement-based material having the same composition as the fiber-reinforced cement-based material constituting the waterproof layer is poured into the space surrounded by the upper surface of the interstitial concrete and the edge of the waterproof layer of the adjacent precast floor slab. A method of constructing a floor slab, comprising:

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