Steel floor slab upper surface thickening reinforcement structure and steel floor slab upper surface thickening reinforcement method by uhpfrc

Abstract

To provide a steel floor slab upper surface thickening reinforcement structure and a steel floor slab upper surface thickening reinforcement construction method by UHPFRC capable of stably fixing an adhesive on an interface between the UHPFRC and a steel floor slab.SOLUTION: A steel floor slab upper surface thickening reinforcement construction method comprises an adhesive application step of applying an adhesive to the upper surface of a steel plate deck 11, a granular fluidization prevention material charging step of charging a granular fluidization prevention material 121 capable of suppressing fluidization of the adhesive to the adhesive applied to the steel plate deck 11, and a UHPFRC placing step of placing a UHPFRC13 on the upper part of the adhesive after the particulate fluidization prevention material charging step.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a steel deck top surface thickening reinforcement structure and steel deck top surface thickening reinforcement method using UHPFRC, in which UHPFRC is cast onto the top surface of a steel deck to thicken the cross section of the component. [Background technology]

[0002] Conventionally, steel fiber reinforced concrete (hereinafter, SFRC) has been widely used in the steel deck top surface thickening method. Patent Document 1 discloses that an adhesive layer 15 is interposed between the SFRC layer 16 and the deck plate 10, and an epoxy adhesive is used as the adhesive. This configuration can prevent the SFRC from peeling off. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6499802 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, there have been reports of fatigue cracks that progress to the deck plate at the welds between the U-ribs of steel decks and the deck plate. Therefore, as a countermeasure, the inventors of this application considered that the local deformation of the deck plate could be effectively suppressed by using ultra-high performance fiber reinforced cementitious composite material (hereinafter referred to as UHPFRC), which has a higher elastic modulus than SFRC.

[0005] However, when reinforcing a steel deck with UHPFRC, an adhesive is essential for integrating the steel deck with cementitious materials. However, laboratory tests revealed a problem: as shown in the photograph in Figure 1, the high fluidity and viscosity of UHPFRC causes the adhesive to be pushed out, leaving no adhesive at the interface between the UHPFRC and the steel plate, and the required adhesive effect cannot be obtained.

[0006] In view of the above-mentioned problems, the present invention aims to provide a steel deck top surface thickening reinforcement structure and a steel deck top surface thickening reinforcement construction method using UHPFRC, which enable stable adhesion of adhesive to the interface between the UHPFRC and the steel deck. [Means for solving the problem]

[0007] The invention related to (1) is a method for reinforcing the upper surface of a steel deck using UHPFRC, characterized by having at least an adhesive application step of applying adhesive to the upper surface of a steel deck, a granular fluidization prevention material injection step of injecting a granular fluidization prevention material capable of suppressing the flow of the adhesive into the adhesive applied to the steel deck, and a UHPFRC pouring step of pouring UHPFRC on top of the adhesive after the granular fluidization prevention material injection step.

[0008] The invention related to (2) is a method for reinforcing the upper surface of a steel deck using UHPFRC, characterized by having at least a granular fluidization prevention material premixing step of premixing a granular fluidization prevention material capable of suppressing the flow of the adhesive into the adhesive, a premixed adhesive application step of applying the fluidization prevention adhesive premixed with the granular fluidization prevention material to the upper surface of a steel deck, and a UHPFRC pouring step of pouring UHPFRC on top of the fluidization prevention adhesive premixed with the granular fluidization prevention material after the premixed adhesive application step.

[0009] The invention related to (3) is a method for reinforcing the upper surface of a steel deck using UHPFRC as described in (1) or (2) above, in which the granular fluidization prevention material is made of a plurality of granules that have a higher specific gravity and are harder than the adhesive.

[0010] The invention related to (4) is a steel deck upper surface thickening reinforcement structure using UHPFRC, which has at least a fluidization prevention adhesive layer formed on the upper surface of the steel deck and a UHPFRC layer formed on top of the fluidization prevention adhesive layer, characterized in that the fluidization prevention adhesive layer contains a granular fluidization prevention material that can suppress the flow of the adhesive.

[0011] The invention related to (5) is a steel deck upper surface thickening reinforcement structure using UHPFRC as described in (4) above, in which the granular fluidization prevention material is made of a plurality of granular materials that have a higher specific gravity and are harder than the adhesive. Effect of the Invention

[0012] According to the inventions relating to (1) and (4) above, by suppressing extrusion using the granular fluidization prevention material, it is possible to effectively prevent the adhesive from being extruded by pouring the UHPFRC.

[0013] According to the invention related to (2) above, by suppressing extrusion using the granular fluidization prevention material, it is possible to effectively prevent the adhesive from being extruded by the pouring of UHPFRC. In addition, since the premixed fluidization prevention adhesive can be applied to the top surface of the steel deck at the construction site, it is possible to reduce the effort required to add granular fluidization prevention material at the construction site.

[0014] According to the inventions related to (3) and (5) above, a granular material that has a higher specific gravity and is harder than the adhesive can be suitably used as the granular fluidization prevention material. For example, silica sand, crushed sand, or iron balls such as those used in shot blasting can be added to the adhesive in multiple amounts or premixed with the adhesive. [Brief description of the drawings]

[0015] [Figure 1] This is a photographic image showing the adhesive on a steel plate being pushed out by UHPFRC. [Diagram 2] 1 is a part of a construction flow for a steel deck top surface thickening reinforcement method in one embodiment of the present invention. [Diagram 3] 11 is a part of a construction flow of a steel deck upper surface thickening reinforcement method in another embodiment of the present invention. [Figure 4] 1A and 1B are cross-sectional views of a steel deck upper surface thickening reinforcement structure of the present invention, in which (a) is a cross-sectional view of one embodiment of the present invention, and (b) is a cross-sectional view of another embodiment of the present invention. [Diagram 5]1 is a table showing laboratory test results for one embodiment of the present invention. [Figure 6] 1A and 1B are diagrams showing an example of a UHPFRC formulation in one embodiment of the present invention, where FIG. 1A is a formulation table and FIG. 1B is a table explaining the symbols in the formulation table. [Figure 7] 1 is a photographic image showing how the present invention prevents adhesive on a steel plate from being pushed out by UHPFRC. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, with reference to the drawings, embodiments of the steel deck upper surface thickening reinforcement structure and steel deck upper surface thickening reinforcement construction method using UHPFRC of the present invention will be described.

[0017] A part of the construction flow of a method for reinforcing the upper surface of a steel deck according to one embodiment of the present invention is shown in Fig. 2. That is, after a steel deck cleaning step (S100) in which the surface of the steel deck is cleaned by sandblasting or the like, a primer application step (S110) is carried out in which a primer is applied to the steel deck after cleaning to protect it from rust.

[0018] Further, an adhesive application step (S120) is carried out in which adhesive is applied to the upper surface of the steel deck, and a granular fluidization prevention material injection step (S130) is carried out in which a granular fluidization prevention material capable of suppressing the flow of the adhesive is injected into the adhesive applied to the steel deck.

[0019] After the granular fluidization prevention material injection step (S130), a UHPFRC pouring step (S140) is carried out to pour UHPFRC on top of the adhesive. This forms a steel deck top surface thickening reinforcement structure as shown in Figure 4(a).

[0020] The construction flow described above makes it possible to effectively prevent the adhesive from being pushed out by the pouring of UHPFRC by suppressing extrusion using granular fluidization prevention material.

[0021] 3 shows a part of the construction flow of a steel deck top surface thickening reinforcement method in another embodiment of the present invention. That is, what differs from the above-mentioned embodiment is that it includes a granular fluidization prevention material premixing step (S121) in which a granular fluidization prevention material is premixed with the adhesive, and a premixed adhesive application step (S131) ​​in which the fluidization prevention adhesive with the granular fluidization prevention material premixed therein is applied to the top surface of the steel deck.

[0022] According to the construction flow of this alternative embodiment, there are disadvantages in that it is time-consuming to premix the granular fluidization prevention material into the adhesive in advance and that premixed adhesive is more difficult to apply than a non-premixed adhesive. However, by applying premixed anti-fluidization adhesive to the top surface of the steel deck at the construction site, it is possible to reduce the time-consuming task of adding granular fluidization prevention material at the construction site and further, it is possible to apply the granular fluidization prevention material more evenly than if it were spread by hand on site.

[0023] Next, Figure 4 shows the cross-sectional configuration of the steel deck upper surface thickening reinforcement structure, where (a) shows a cross-sectional view of the embodiment described above, and (b) shows a cross-sectional view of the other embodiment described above.

[0024] In other words, regardless of the construction flow, the steel deck upper surface thickening reinforcement structure is composed of at least a fluidization prevention adhesive layer 12 formed on the upper surface of the steel deck 11, and a UHPFRC layer 13 formed on top of the fluidization prevention adhesive layer 12, and the fluidization prevention adhesive layer 12 contains a granular fluidization prevention material 121 that is capable of suppressing the flow of the adhesive.

[0025] As can be seen from the cross-sectional view of Figure 4(a), when the granular fluidization prevention material 121 is poured in after adhesive has been applied to the top surface of the steel deck 11, the surface of the granular fluidization prevention material 121 will be exposed. On the other hand, when the granular fluidization prevention material 121 is premixed with the adhesive, the surface of the granular fluidization prevention material 121 will be covered with the adhesive.

[0026] As the granular fluidization prevention material 121, a granular material that has a higher specific gravity and is harder than the adhesive can be suitably used. For example, silica sand, crushed sand, or iron balls such as those used in shot blasting can be added to the adhesive in multiple amounts or premixed with the adhesive.

[0027] According to the steel deck top surface thickening reinforcement method and steel deck top surface thickening reinforcement structure described above, when UHPFRC is poured, it is possible to effectively prevent the adhesive from being pushed out into the UHPFRC.

[0028] (Laboratory test results) Next, an embodiment of a laboratory test for suppressing extrusion of adhesive by using a granular fluidization inhibitor will be described.

[0029] For the indoor tests, a sandblasted steel plate (400mm x 400mm) was prepared to resemble a steel deck, and an epoxy resin-based primer of the same type as the adhesive was applied to the surface of the steel plate.

[0030] After the primer has dried sufficiently, apply the specified amount of 1.4 kg / m2 of two-liquid epoxy resin adhesive for bonding to concrete. 2 To prevent the adhesive from being pushed out, granular fluidization prevention material (No. 3 silica sand) was applied at a rate of 1.0 kg / m 2 The mixture was then hand-sprinkled onto the adhesive surface.

[0031] After adding the granular fluidization prevention material to the adhesive, the UHPFRC is poured and spread evenly using a vibrating trowel to reproduce a concrete finisher. Note that although an ultra-fast hardening type of UHPFRC was used in this test, general UHPFRC can be used for on-site construction, and an example of a UHPFRC mix table is shown in Figure 6.

[0032] After pouring and spreading the UHPFRC as described above, the jig for the adhesion test was fixed within the usable time of the UHPFRC, and an adhesion strength test was conducted after 24 hours (curing indoors at 20°C). The adhesion strength test was conducted using the Construction Research Institute type tensile tester (φ100mm).

[0033] Figure 5 shows the results of the laboratory test mentioned above. When observing the presence or absence of adhesive extrusion during the casting of UHPFRC, among cases where granular fluidization prevention material was added to the adhesive, when UHPFRC was cast 30 and 60 minutes after the addition of the granular fluidization prevention material, no adhesive extrusion occurred. Also, when UHPFRC was cast 0 minutes after the addition of the granular fluidization prevention material, slight wrinkles occurred in the adhesive.

[0034] Figure 7 shows a photograph of the situation in which the adhesive on the steel plate is prevented from being pushed out by the UHPFRC. As is clear from a comparison with the photograph in Figure 1, it can be seen that the inclusion of a granular fluidization prevention material in the adhesive very effectively prevents the adhesive from being pushed out.

[0035] In addition, as shown in Figure 6, in the adhesive tensile test, all cases in which granular fluidization prevention material was added were within the standard value of 1.0 N / mm (Metropolitan Expressway Company Limited: Technical data on fatigue countermeasures for steel structures - Technical data on fatigue countermeasures for existing steel decks). 2 The above adhesive strength was met, and it was confirmed that the adhesive was not extruded and that the adhesive effect was fully exerted between the UHPFRC and the steel plate.

[0036] (Other embodiments) Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-mentioned configurations, and the following modifications are possible.

[0037] For example, in the laboratory tests mentioned above, No. 3 silica sand was used as the granular fluidization prevention material, but the material is not necessarily limited to such granular material or particle size, and any material that can adequately suppress the extrusion of adhesive can be used.

[0038] In addition, the amount of granular fluidization prevention material added was 1.0 kg / m in laboratory tests. 2 The adhesive was applied to the surface by hand at 0.5 kg / m 2By setting the above, it is possible to obtain the effect of suppressing the extrusion of the adhesive.

[0039] The above describes the embodiments of the present invention. The scope of the present invention is indicated by the claims, not by the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims. In addition, the specific materials, dimensions, shapes, etc. described in the above embodiments can be modified within the scope of solving the problems of the present invention. [Explanation of symbols]

[0040] 11 Steel deck slab 12 Anti-fluidization adhesive layer 13 UHPFRC layer 121 Granular fluidization prevention material

Claims

1. An adhesive application step of applying an adhesive to an upper surface of the steel deck; A granular fluidization prevention material injection step of injecting a granular fluidization prevention material capable of suppressing the flow of the adhesive into the adhesive applied to the steel deck; The method includes at least a UHPFRC casting step of casting UHPFRC on top of the adhesive after the granular fluidization prevention material casting step. A method for reinforcing the upper surface of a steel deck using UHPFRC.

2. A granular fluidization inhibitor premixing step of premixing an adhesive with a granular fluidization inhibitor capable of suppressing the flow of the adhesive; A premixed adhesive application step of applying a fluidization prevention adhesive in which the granular fluidization prevention material is premixed onto an upper surface of a steel deck; The method includes at least a UHPFRC casting step of casting UHPFRC on the top of the fluidization prevention adhesive in which the granular fluidization prevention material is premixed after the premix adhesive application step. A method for reinforcing the upper surface of a steel deck using UHPFRC.

3. The granular fluidization prevention material is made of a plurality of granular materials having a higher specific gravity and a harder property than the adhesive. A method for reinforcing the upper surface of a steel deck by increasing its thickness using the UHPFRC according to claim 1 or 2.

4. A fluidization prevention adhesive layer formed on the upper surface of the steel deck; and a UHPFRC layer formed on the top of the fluidization-preventing adhesive layer; The fluidization-preventing adhesive layer contains a granular fluidization-preventing material capable of suppressing the fluidization of the adhesive. A steel deck upper surface thickening reinforcement structure using UHPFRC.

5. The granular fluidization prevention material is made of a plurality of granular materials having a higher specific gravity and a harder property than the adhesive. A steel deck upper surface thickening reinforcement structure using the UHPFRC according to claim 4.

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