JP2012132191A - Covering method and covering structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exfoliation preventing covering technique capable of easily checking whether or not high exfoliation prevention is secured, thereby surely preventing exfoliation of a covering material further, at the low execution cost.SOLUTION: A covering method of a structure surface for putting a covering material 4 on so as to cover at least a part of a covering material exfoliation prevention member 2 hooked to a tapping screw 5 provided on a structure 1 includes: a step (a) of providing the tapping screw 5 on the structure 1; a step b of hooking and fixing the covering material exfoliation prevention member 2 to the tapping screw 5; a step c of providing the covering material 4 so as to cover at least a part of the covering material exfoliation prevention member 2; and a measuring step of measuring whether or not the tapping screw 5 provided on the structure 1 satisfies a condition of a penetration index threshold of the tapping screw 5 demanded beforehand and holds prescribed drawing strength before the covering material 4 is provided and after the tapping screw 5 is provided.

Description

  The present invention relates to a covering structure.

  Iron (for example, steel, cast iron) is used for structures such as tunnels and viaducts. And the surface of the said structure often exposed the iron material which is a structural material (component material). By the way, in the event of a fire, the iron strength is severely reduced. Iron is easy to transmit heat. In view of the above, the cementitious lightweight coating material is often coated on the surface of an iron structure (a structure including iron as a constituent material).

  By the way, there is a possibility that the cementitious lightweight coating material covering the surface may peel off. Therefore, a technique has been proposed for preventing the cemented lightweight coating material from peeling off even when the coated cementitious lightweight coating material is peeled off from the surface of the iron structure. That is, it has been proposed that a net-like, rod-like or mesh-like peeling prevention material is attached to the surface of an iron structure, and the cement-type lightweight coating material is coated so that the peeling prevention material is embedded.

  Japanese Unexamined Patent Application Publication No. 2009-235890 proposes a method of attaching a peeling prevention material to the surface of an iron structure. For example, a method has been proposed in which a hole is formed in an iron structure, a post-fixed anchor (bolt) is fixed to the hole, and a peeling prevention material is fastened to the surface of the iron structure with a nut passed through the bolt. Alternatively, a method has been proposed in which a hole provided with a thread is provided in an iron structure, a bolt is screwed into the hole, and a peeling prevention material is fastened to the surface of the iron structure with a nut passed through the bolt. . Alternatively, a bolt-fastening insert or nut is fixed to the back side of the hole provided in the steel structure, and a bolt is screwed into the bolt-fastening insert or the like. A method of fastening by fastening to the surface has been proposed.

JP 2009-235890 A

  However, the method of attaching the anti-peeling material of Patent Document 1 to the surface of an iron structure takes time. Therefore, a technique that is easy to construct is required.

  By the way, when the peeling prevention material is provided, it has been found that a corrosion phenomenon occurs near the contact portion between the peeling prevention material and the iron structure. As a result of consideration of this corrosion phenomenon, it has been found that this may be based on the following. That is, in most cases, the iron structure and the peeling prevention material or the peeling prevention material fixing metal fitting are dissimilar metals. It is no exaggeration to say that there is no case where the constituent material of the iron structure is the same material as the constituent material of the peeling prevention material or the peeling prevention material fixing bracket. Incidentally, the material of the iron structure is carbon steel (ordinary steel) or cast iron, and the material of the peeling prevention material or the peeling prevention material fixing bracket is stainless steel. However, the corrosion phenomenon does not occur simply by saying that it is a dissimilar metal. That is, when the constituent material is a dissimilar metal and water intervenes, a local battery is formed between the two and a corrosion phenomenon occurs. As a result, the iron structure is easily corroded. The surface of the iron structure is generally subjected to anticorrosion coating. However, the anticorrosion coating is only performed from the viewpoint of general anticorrosion. In other words, it was not an anti-corrosion coating from the viewpoint of preventing corrosion at the joint between the steel structure and the anti-separation material or anti-separation material fixing bracket. No anticorrosive coating was performed up to the inside of the (through hole). Moreover, complete anticorrosion coating up to the inside of the hole is very time-consuming and requires attention. Therefore, such processing is costly and difficult to perform in reality.

  Therefore, even in the event of a fire by the present inventors, the fire does not directly hit the iron material of the iron structure, and in order to prevent a significant decrease in the mechanical strength of the iron material, When coated with a lightweight cementitious coating material, and when the anti-separation material or anti-separation material fixing bracket is used to prevent the cementitious lightweight coating material from peeling off, the corrosion phenomenon is unlikely to occur. A technique has been provided in which the work for preventing the corrosion phenomenon is simple.

  That is, a method for coating a surface of an iron structure in which a cementitious lightweight coating material is coated on the surface of the iron structure so that a peeling prevention material provided on the surface of the iron structure is embedded, and the iron structure is not yet covered. The anti-slipping material is sandwiched between the step A in which a through hole is provided, the step B in which a tapping screw is screwed into the non-through hole, and the screwed tapping screw and the surface of the iron structure. A steel structure surface comprising: a step C in which a material is fixed on the surface of the iron structure; and a step D in which a cementitious lightweight coating material is coated on the surface of the iron structure so that the anti-slipping material is embedded. A coating method was proposed.

  Now, improvement of the proposed technique has been required. That is, it is difficult to determine whether or not the screwed tapping screw is firmly screwed. When the screwed tapping screw is easily pulled out, it is considered that the prevention of peeling of the cementitious lightweight coating material coated on the surface of the iron structure is insufficient. However, in order to confirm whether or not the screwed tapping screw can prevent peeling from the surface of the structure due to the weight of the cementitious lightweight coating material in which the peeling prevention material is present, It was necessary to check whether or not the tapping screw could not be removed by applying a load of. Here, the predetermined load is a force obtained by multiplying the total weight of the covering material and the flaking prevention material received by one tapping screw by a safety factor when the cement-based lightweight coating material peels from the surface of the iron structure. is there.

  However, it is very difficult to confirm that a predetermined load is applied to all the tapping screws that have been screwed in and that they cannot be removed. It takes too much time and effort. Furthermore, even if all the tapping screws are not removed, there remains a concern that the tapping screws may be slightly removed easily due to the pulling force applied to check the safety. Since it is difficult to investigate all the tapping screws that have been screwed in, if a sampling inspection is performed, there remains a concern about a problem with the tapping screws that have not been inspected.

  Therefore, the problem to be solved by the present invention is to solve the above problems. That is, it is possible to easily check whether or not high peeling prevention can be ensured, and therefore, to provide a peeling prevention coating technique that can more reliably prevent the coating material from peeling off and that can be implemented at low cost.

The above issues are
A coating method for the surface of a structure in which a coating material is coated so that at least a part of the coating material peeling prevention material hooked on a tapping screw provided in the structure is covered,
A step a in which a tapping screw is provided on the structure;
A step b in which the covering material peeling prevention material is fixed to the tapping screw;
Step c in which a covering material is provided so that at least a part of the covering material peeling prevention material is covered.
And comprising
Before the covering material is provided and after the tapping screw is provided,
A measuring step of measuring whether or not the tapping screw provided in the structure satisfies a predetermined tapping screw penetration index threshold condition and maintains a predetermined pulling strength. It is solved by the coating method on the surface of the structure.

  Preferably, in the covering method for the surface of the structure, and when the tapping screw provided in the structure does not satisfy the condition of the penetration index threshold value of the tapping screw determined in advance, the step c is preceded. The tapping screw is further screwed in until the condition of the penetration index threshold value is satisfied, and this is solved by the covering method for the surface of the structure.

  In the covering method for the structure surface, the measuring step is, for example, a step in which a protruding height of the tapping screw provided in the structure from the surface of the structure to a predetermined portion of the tapping screw is measured. For example, the projecting height of the tapping screw is measured from the surface of the tapping screw provided in the structure. Or it is the process by which the distance between the head of the tapping screw provided in the structure and the surface of the structure is measured.

The above issues are
The structure surface covering method is implemented, and is solved by a structure in which a covering material is coated so that at least a part of the covering material peeling prevention material hooked on a tapping screw provided in the structure is covered. The

  A structure formed by coating with a coating material with high reliability for preventing peeling can be obtained at low cost.

Schematic when measuring the pull-out load of a tapping screw Graph showing the relationship between the pull-out load of the tapping screw and the protruding height of the tapping screw Graph showing the relationship between the pull-out load of the tapping screw and the hole diameter (drill diameter) into which the tapping screw is screwed Schematic when measuring the protruding height of the tapping screw Schematic of tapping screw Schematic process diagram of the method of the present invention Schematic diagram of covering material peeling prevention material Schematic diagram of covering material peeling prevention material

  The first aspect of the present invention is a coating method. In particular, it is a coating method for the surface of a structure in which the coating material is coated so that at least a part of the coating material peeling prevention material hooked on a tapping screw provided in the structure is covered. The structure is, for example, an iron structure. The coating material is, for example, a cement-based lightweight coating material. Therefore, for example, a coating method in which the surface of an iron structure is coated with a cement-based lightweight coating material. A coating material peeling prevention material is provided on the surface of the structure, and the coating material peeling prevention material is embedded by the coated cementitious lightweight coating material. In addition, although this embedment is preferably a complete embedment, a case of partial exposure and partial embedment can be considered. Of course, the entire embedment is preferable. This construction method includes step a. In this step a, a tapping screw is provided on the structure. For example, a tapping screw is screwed into a prepared hole (through hole or non-through hole) drilled in the structure. Therefore, this step includes a step of providing a pilot hole in the structure and a step of screwing a tapping screw into the pilot hole depending on circumstances. This construction method includes step b. In this step b, the covering material peeling prevention material is hooked and fixed to the tapping screw. The covering material peeling prevention material is, for example, a net-like, rod-like, linear, mesh-like or sheet-like one. This covering material peeling prevention material (also referred to as a fixing material in some cases) is attached (fixed: hooked) with a tapping screw with a gap (gap: gap) between the structure and the structure. ) In particular, the covering material peeling prevention material is sandwiched between the screwed tapping screw and the structure surface, and the peeling prevention material is fixed to the structure surface. The attachment portion of the peeling prevention material may be a part of the peeling prevention material. At the time of attachment, a fitting or a resin or ceramic attachment member may be used. This construction method includes step c. In this step c, the covering material is provided so that at least a part of the covering material peeling prevention material is covered. The coating material is, for example, a cement-based lightweight coating material. This construction method preferably includes a step of waterproofing a screwed portion between the pilot hole and the tapping screw. For example, the waterproof elastic packing preferably includes a step of being sandwiched between the surface of the structure and the attachment portion and / or between the attachment portion and the head of the tapping screw.

  This construction method comprises the following measurement steps. This measurement process is performed before the covering material is provided and after the tapping screw is provided. This measurement step is a step performed to determine whether or not the tapping screw provided in the structure satisfies a predetermined tapping screw penetration index threshold value and maintains a predetermined pulling strength. It is. For example, in the measurement process, the tapping screw provided in the structure protrudes from the surface of the structure to a predetermined location of the tapping screw (a position (location) serving as a mark, which may be determined as a position xmm from the top of the head). This is a process in which the height is measured. For example, the projecting height of the tapping screw is measured from the surface of the tapping screw provided in the structure. Or it is the process by which the distance between the head of the tapping screw provided in the structure and the surface of the structure is measured. Preferably, when the tapping screw provided in the structure does not satisfy the predetermined condition of the penetration index threshold value of the tapping screw (when the predetermined pulling strength is not maintained), the step c is performed. In advance, the method further includes a step of further screwing the tapping screw until the penetration index threshold value (predetermined pulling strength) is satisfied.

  The second present invention is a structure. This structure is obtained by performing a coating method on the surface of the structure. That is, it is a structure in which the covering method is applied and the covering material is covered so that at least a part of the covering material peeling prevention material hooked on the tapping screw provided in the structure is covered.

  This will be described in more detail below.

  The structure in the present invention is an iron structure, for example. It is a steel (especially ordinary steel) structure. Alternatively, it is a cast iron structure. Or it is a concrete structure. Other examples include wooden structures, stone structures, and resin structures. Or the structure made from the composite material with which the said raw material was combined suitably is mentioned. Specific examples include ordinary steel segments, cast iron segments, synthetic segments made of steel and concrete, and synthetic segments made of cast iron and concrete. A tunnel using metal as a structural member, such as a shield tunnel composed of one or two or more segments as described above, or a steel shell concrete submerged tunnel, a mountain tunnel composed of concrete and steel, a steel tank, a reinforced concrete tank, Steel bridge piers, steel viaducts, reinforced concrete viaducts, steel pipes, steel frames, steel plates or steel pipe filled concrete, buildings with roofs, columns, beams or floors, submerged tunnels filled with concrete inside steel shells Wooden houses, steel-frame houses, concrete houses, etc.

  The pilot hole previously drilled in the structure has a smaller inner diameter than the diameter of the tapping screw used. When the structure is an iron structure, the prepared hole is preferably a non-through hole. If it is allowed to penetrate, water may permeate from there when there is groundwater on the back surface of the structure where the pilot hole (through hole) is drilled, which may cause corrosion of the metal.

  The shape and size of the tapping screw are determined by the inner diameter and depth of the pilot hole formed in the structure. Preferably, any material that can withstand the total weight of the coated cementitious lightweight coating material and the flaking prevention material by the tapping screw screwed into the pilot hole may be used.

  From the viewpoint of preventing corrosion, it is preferable that the material of the anti-slipping material and the material of the tapping screw are the same (same or equivalent). If they are of the same system, the potential difference is small, and corrosion is unlikely to occur even if they are in contact. Incidentally, the anti-peeling material is often made of stainless steel. Accordingly, the material of the tapping screw is also preferably stainless steel.

  The anti-peeling material is often composed of one or more selected from metal, ceramic, resin, glass, and carbon as the main material. Specifically, it is a material that hardly corrodes or rusts such as stainless steel, rust-prevented metal, resin, alkali-resistant glass, and carbon. From the viewpoint of fire resistance, nonflammable (flame retardant) materials are preferred. For these reasons, stainless steel, rust-proof metal, ceramic, alkali-resistant glass, and the like are particularly preferable. Of these, stainless steel is preferable.

  The shape of the exfoliation preventing material may be any selected from a net shape, a rod shape, a line shape, a mesh shape, or a perforated sheet shape. In addition, when arrange | positioning a cement-type coating | covering material on the structure surface by a spraying construction method, the shape of a peeling prevention material has a net | network shape, rod shape, or a linear form from the sprayability of a cement-type coating | covering material.

  As a covering material (for example, cement-based lightweight coating material), a fireproof coating mortar made of cement, water, an admixture, a lightweight aggregate, and the like can be cited as a preferable example. A heat-insulating mortar having a similar composition may also be mentioned. Fireproof coating materials, heat insulating materials, heat insulating materials, sound absorbing materials, etc., consisting of a mixture of mineral fibers such as rock wool, mineral fibers such as rock wool, cement, water, and admixtures mixed as necessary Also mentioned. A bubble mortar having bubbles bubbled by a foaming agent in a cement mortar in which cement, water, fine aggregate, and an admixture are mixed is also included. Examples include lightweight mortar in which cement, water, a foaming agent, and other admixtures are mixed. Of course, it is not limited to these

  As described above, the essential essential process in this construction method, that is, the measurement process, the tapping screw provided in the structure satisfies the predetermined condition of the penetration index threshold value of the tapping screw and maintains a predetermined pulling strength. This is a step of measuring whether or not the For example, the relationship between the index representing the penetration depth of the tapping screw and the pulling load (strength) is required in advance. For example, a tapping screw is screwed into a structure (simulated structure) at a place where construction is performed, and a pulling load is obtained in the form as shown in FIG. 1, and data as shown in FIGS. ing. According to this, when a tapping screw having a diameter of the pilot hole (drill diameter) of XX mm, a shaft diameter of YY mm, and a length of ZZ mm is screwed into the prepared hole of the structure, the screwed tapping screw The relationship between the protrusion height from the structure surface and the pull-out load is known. Therefore, if the protruding height of the tapping screw is measured, it can be understood that a WW load is required to pull out the tapping screw. In other words, how much pull-out load of the tapping screw should be secured can be calculated from the total weight of the covering material and anti-separation material. The thickness is measured, and if it is smaller than the reference value (threshold value), it can be determined that it is acceptable. Since it can be determined only by measuring the protruding height of the tapping screw, it can be carried out very smoothly and easily. If the protruding height of the tapping screw exceeds a reference value (threshold value), the tapping screw is screwed in until it reaches a predetermined value. The strength (torque) for screwing the tapping screw is determined by the inner diameter (drilling diameter) of the pilot hole formed in the structure and the shape and size of the tapping screw. Therefore, the strength for screwing the tapping screw is a strength that satisfies the conditions of the penetration index threshold value of the tapping screw, and the strength that does not cause the breakage of the pilot hole formed in the structure when the tapping screw is screwed. It is preferable that

The measurement process of the present invention is performed as follows. The index representing the penetration depth of the tapping screw is the penetration depth of the screwed tapping screw. Any index that can be converted into the penetration depth of the tapping screw may be used. As an index representing the penetration depth (D ₁ ) of the tapping screw, for example, the protruding height (H) of the tapping screw from the surface of the structure or the distance (D ₂ ) between the structure surface and the head of the tapping screw, etc. Can be mentioned. That is, I determined the length of the tapping screw, wherein D ₁ can be substituted I than in the H and D _2. The relationship between these indices and the length (full length) (L ₁ ) of the tapping screw is expressed by the following equations (1) to (3). The height of the head of the tapping screw is (H _H ), and the length under the neck (axial length) is (L ₂ ).
Equation _{(1) D 1 = L 1} -H
Equation _{(2) D 1 = L 1} - (D 2 + H H)
Equation _{(3) D 1 = L 2} -D 2

In this case, when such duty coating on the structure surface is applied, it is preferable to substitute the D ₁ in the H or D ₂ thereof paint thickness (T) is also taken into account. When considering T, the equations (1) to (3) are respectively expressed by the following equations (4) to (6). If it can be determined that the thickness of the coating (T) applied to the surface of the structure is thin and the effect of substituting the penetration depth (D ₁ ) of the tapping screw with H or D ₂ is slight, The correction may be omitted.
Equation _{(4) D 1 = L 1} -H-T
Equation _{(5) D 1 = L 1} - (D 2 + H H + T)
Equation _{(6) D 1 = L 2} -D 2 -T

A method of measuring an index representing the penetration depth of the tapping screw such as H, D ₂ is not particularly limited. For example, a caliper, a micrometer, a ruler, a gap gauge or the like is used as appropriate. FIG. 4 shows a schematic diagram in which when a tapping screw is screwed into a steel plate provided with a pilot hole, the projecting height (H) of the structure surface and the tapping screw is measured with a micrometer.

  Hereinafter, specific examples will be given and described. Of course, the present invention is not limited to this.

  FIG. 5 is a schematic view of the tapping screw used. 6A, 6B, 6C, and 6D are process diagrams of the coating method according to the present invention. FIG. 7 is a schematic plan view of a peeling prevention material made of a stainless steel wire mesh. FIG. 8 is a schematic plan view showing a state in which a peeling prevention material made of a stainless steel wire mesh is attached to the surface of the steel structure.

  In each figure, 1 is an iron structure in various structures such as buildings and tunnels. Reference numeral 2 denotes a wire mesh (a peeling prevention material). Reference numeral 3 denotes a non-through hole (a pilot hole) formed at a desired location of the iron structure 1. 4 is a cement-type lightweight coating | covering material. Reference numeral 5 denotes a tapping screw. 6 is a flat washer. 7 is a waterproof / insulating elastic packing. Reference numeral 8 denotes an attachment portion of the wire mesh 2. As can be seen from FIG. 8, the attachment portion 8 is configured by bending and projecting a part of the wire and shortening the width between the wire and the wire. That is, the wire mesh 2 can be attached with the tapping screw 5 by configuring the width of the wire to be shorter than the diameter of the flat washer 6 or the width of the head of the tapping screw 5. Reference numeral 9 denotes the surface of the iron structure 1. Reference numeral 10 denotes a screwed portion between the non-through hole (prepared hole) 3 and the tapping screw 5. Reference numeral 11 denotes a head of the tapping screw 5. Reference numeral 12 denotes a screw hole (cross hole). Reference numeral 22 denotes a groove provided for tapping.

First, as shown in FIG. 6A, a pilot hole (non-through hole) 3 that does not pass through an iron material such as a steel plate constituting the iron structure is formed at a desired location of the iron structure 1. This step is a step in which a non-through hole is provided in the iron structure. The depth of the pilot hole 3 depends on the axial length (L ₂ ) of the tapping screw 5, but may be slightly longer or shorter than the axial length. However, when the tapping screw 5 is screwed and the pilot hole 3 is a non-through hole, it is preferable that the tip of the tapping screw does not contact the bottom of the pilot hole. In this sense, the axial length (L ₂ ) of the tapping screw 5 includes the thickness of the iron material of the iron structure 1, the thickness of the attachment portion of the peeling prevention material (the thickness of the wire material of the wire mesh attachment portion), and the flat washer 6. It is preferably shorter than the total value of the thickness. Since the pilot hole 3 is a non-through hole, moisture from the back side of the iron structure 1 (the left side of the iron structure 1 in FIG. 6) is removed from the front side of the iron structure 1 (the iron structure in FIG. 6). No entry to the right of 1). Incidentally, if the pilot hole 3 is not a non-through hole but a through hole, moisture from the back side of the iron structure 1 (the left side of the iron structure 1 in FIG. 6) is transferred to the front side of the iron structure 1. There is a high possibility of entering (in FIG. 6, the right side of the iron structure 1).

  Next, as shown in FIG. 6B, the elastic packing 7, the wire mesh 2, and the flat washer 6 are arranged on the iron structure 1. This step is a preliminary (front) step in which the screwed portion between the non-through hole and the tapping screw is waterproofed. The elastic packing 7 used here has a thickness greater than the thickness of the wire mesh 2.

  Then, as shown in FIGS. 6B and 6C, the tapping screw 5 is arranged, and the tapping screw 5 is screwed into the prepared hole 3. As a result, the wire mesh 2 is fixed. In this process, the anti-separation material (metal mesh 2) is sandwiched between the process of screwing the tapping screw into the prepared hole and the surface of the tapping screw screwed in and the iron structure surface, and the anti-separation material 2 is the surface of the iron structure 1 It is a process fixed to. Furthermore, this process completes the process of waterproofing the threaded portion between the pilot hole and the tapping screw. That is, the wire mesh 2 is sandwiched between the elastic packing 7 pressed against the surface 9 of the iron structure 1 and the flat washer 6, and the flat washer 6 has a tapping screw 5 screwed into the non-through hole 3. Power is acting. Accordingly, the wire mesh 2 is firmly fixed to the iron structure 1. In addition, as a result, waterproofing is performed. Therefore, even if the iron structure 1 and the wire mesh 2 are dissimilar metals, there is an insulating (non-metallic) elastic packing 7 between them, so that moisture exists temporarily. However, it is difficult to form a local battery. That is, corrosion hardly occurs. The opening of the pilot hole 3 is sealed by the elastic packing 7, the flat washer 6, and the head 11 of the tapping screw 5, and there is no possibility of moisture entering the pilot hole 3. This means that even if the tapping screw 5 and the iron structure 1 are made of different metals and the tapping screw 5 and the iron structure 1 are coupled (joined) in the pilot hole 3, they are locally It is difficult to form a battery. That is, corrosion hardly occurs. If the wire mesh 2, the tapping screw 5, and the flat washer 6 are made of the same material, even if moisture is present here, it is difficult to form a local battery. That is, corrosion hardly occurs.

Now, as shown in FIGS. 6C and 4, the protruding height H of the tapping screw 5 from the surface of the structure 1 is measured with a micrometer. First, the relationship between the tapping screw protrusion height H and the tapping screw pull-out load is obtained in advance (see FIG. 2). Thus, from this relationship, the tapping screw protruding height H ₁ when a predetermined pulling load is obtained, in advance, is sought. Therefore, the tapping screw protrusion height H from the surface of the structure 1 is measured in the step of FIG. Then, it is determined whether or not the measured value H is larger than a reference value H ₁ (tapping screw protrusion height H ₁ that secures a predetermined pulling load obtained in advance). This step is a step of confirming whether or not the index representing the penetration depth of the tapping screw of the tapping screw screwed into the pilot hole is the index representing the penetration depth of the tapping screw that provides a predetermined pulling load. is there. If, structure 1 if the projection height H of the self-tapping screws 5 from the surface exceeds the H _1, the projection height H of the self-tapping screws 5 from the structure 1 surface reaches H ₁ (H is H ₁ The tapping screw 5 is further screwed until it becomes the following. This step is performed when the index representing the tapping screw penetration depth of the tapping screw 5 screwed into the pilot hole 3 does not reach the index representing the tapping screw penetration depth at which a predetermined pulling load is obtained. This is a step of further screwing the tapping screw until reaching an index representing the penetration depth of the tapping screw at which a pull-out load is obtained.

After the step (c), i.e., if it protruding height H of the all-tapping screw is less than the reference value H ₁ has been exceeded is confirmed (reference value H _1, the protruding of the tapping screw after the height has been incorporated further twisted so that the reference value H ₁ below), as shown in FIG. 6 (d), cementitious lightweight dressing fireproofing mortar or the like metal mesh 2 is buried coating The surface 9 of the iron structure 1 is covered with the cementitious lightweight coating material 4. This step is a step in which the cementitious lightweight coating material is coated on the surface of the iron structure so that the peeling prevention material is embedded.

Specific examples will be given below.
A pilot hole 3 was provided in each of 20 locations so that the depth was about 8 mm using a drilling hole having a diameter of 4.5 mm, 4.6 mm, and 4.7 mm on a steel plate having a thickness of 9 mm. A tapping screw having a diameter of 5 mm, a neck length (L ₂ ) of 9.7 mm, and a head height (H _H ) of 3.1 mm was prepared. The tapping screw was screwed into each pilot hole while sandwiching a stainless steel washer having a thickness of 1 mm and a jig for pulling test. At this time, the penetration depth of the tapping screw (D ₁ ), the protruding height of the tapping screw from the steel plate surface (H), and the distance between the steel plate surface and the head of the tapping screw are adjusted by adjusting the number of washers to be sandwiched. was adjusted _{(D 2).}

At this time, the protruding height (H) of the tapping screw from the steel plate surface is 5.7 mm when the number of washers is 0 (when the washers are not sandwiched), 6.7 mm when the number is 1, and 2 When it is 7.7 mm, it is 8.7 mm when it is three. The penetration depths (D ₁ ) are as shown in Table 1, respectively.

Table 1

  A pull-out test of the tapping screw screwed in using a universal testing machine was performed. That is, the pulling load (tensile stress when the tapping screw was pulled out) was measured. An outline of the pull-out test is shown in FIG. In FIG. 1, the thread of the tapping screw is omitted. The results are shown in FIGS. FIG. 2 is a graph showing the relationship between the drawing load for each drill diameter and the protruding height (H) of the tapping screw from the steel plate surface. FIG. 3 is a graph showing the relationship between the drawing load and the drill diameter for each protruding height (H) of the tapping screw from the steel plate surface.

  The characteristic required for the tapping screw, that is, the value (pull-out load) obtained by multiplying the force by which the tapping screw supports the load exceeding the total weight of the peeling prevention material (metal mesh 2) and the cementitious lightweight coating material 4 by the safety factor (pull-out load). Assuming 3000 N, the projection height (H) of the tapping screw from the steel sheet surface is within 7.9 mm when the drill diameter is φ4.5 mm, and within 7.7 mm when the drill diameter is 4.6. It can be seen that if the drill diameter is φ4.7, it should be within 6.7 mm. Therefore, it is determined whether the length measured in the step of FIG. 6C is the above value, and if the protruding height (H) of the tapping screw from the steel plate surface is larger than the above value, Further tapping of the tapping screw is performed.

1 Structure 2 Wire mesh (coating material peeling prevention material)
3 Pilot hole (non-through hole)
4 Cement-based lightweight coating material 5 Tapping screw 6 Flat washer 7 Waterproof / insulating elastic packing 8 Wire mesh mounting part 9 Steel structure surface 10 Threaded portion of pilot hole (unthrough hole) and tapping screw 11 Tapping screw Head 12 Screw hole (cross hole)
19 micrometers

Claims (6)

A coating method for the surface of a structure in which a coating material is coated so that at least a part of the coating material peeling prevention material hooked on a tapping screw provided in the structure is covered,
A step a in which a tapping screw is provided on the structure;
A step b in which the covering material peeling prevention material is fixed to the tapping screw;
Step c in which a covering material is provided so that at least a part of the covering material peeling prevention material is covered.
And comprising
Before the covering material is provided and after the tapping screw is provided,
A measuring step of measuring whether or not the tapping screw provided in the structure satisfies a predetermined tapping screw penetration index threshold condition and maintains a predetermined pulling strength. Covering method for the surface of the structure. When the tapping screw provided in the structure does not satisfy the condition of the penetration index threshold value of the tapping screw that is obtained in advance, prior to step c, the tapping screw is further increased until the tapping screw satisfies the condition of the penetration index threshold value. The method for coating a structure surface according to claim 1, further comprising a step of being screwed. 2. The covering of the structure surface according to claim 1, wherein the measuring step is a step of measuring a protruding height of the tapping screw provided on the structure from the surface of the structure to a predetermined position of the tapping screw. Construction method. 4. The covering method for a structure surface according to claim 3, wherein the measuring step is a step in which a protruding height of the tapping screw is measured from the surface of the tapping screw provided on the structure. 4. The method of covering a structure surface according to claim 3, wherein the measuring step is a step of measuring a distance between a head of a tapping screw provided in the structure and the surface of the structure. The covering method is applied to the surface of the structure according to any one of claims 1 to 5, and the covering material is covered so that at least a part of the covering material peeling prevention material hooked on the tapping screw provided in the structure is covered. Covered structure.

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