JP7724355B1 - Wooden fireproof structure - Google Patents

Abstract

[Problem] To provide a fire-resistant wooden structure that can ensure fire resistance and has excellent workability.
[Solution] A fire-resistant wooden structure 1 used for building columns or beams comprises a wooden structural core material 10 that supports a load, a first covering material 11 that covers the outer surface of the wooden structural core material 10, and a second covering material 12 that covers the outer surface of the first covering material 11. The first covering material 11 contains organic fibers and has a moisture content of 6.0% or more derived from free water or crystal water, while the second covering material 12 has a moisture content of 3.0% or less derived from free water or crystal water. The first covering material 11 is made of either a slag gypsum board or a wood wool cement board, and the second covering material 12 is made of a calcium silicate board.
[Selected Figure] Figure 1

Description

The present invention relates to a wood fire-resistant structure.

Conventionally, fire-resistant structures have been known that can maintain load capacity for long periods of time, even if the surface is carbonized by exposure to flames during a fire, by preventing the core material from carbonizing. One example of a fire-resistant structure is a wooden fire-resistant structure in which a non-combustible material is attached to the outer surface of a wooden structural core material.

For example, Patent Document 1 discloses a wooden building component having a long, rectangular structural section that receives loads, a covering section that covers all four sides of the structural section's cross section along its entire length, and gypsum board that is layered between the structural section and the covering section and prevents the load acting on the structural section from being transmitted to the covering section. Because the structural section is covered with gypsum board, it is not directly exposed to flames and carbonization proceeds very slowly, thereby improving fire resistance. Furthermore, because the surface of the wooden building component is covered with the covering section, the gypsum board is not exposed to the outside, ensuring its appearance.

Patent No. 4359275

Incidentally, the wooden building components described in Patent Document 1 use gypsum board as a non-combustible material. However, gypsum board has the disadvantage of being heavy and difficult to install as a covering material. Therefore, it is not desirable to use gypsum board alone, at least as a covering material to ensure fire resistance.

The present invention therefore aims to provide a fire-resistant wooden structure that not only ensures fire resistance but also offers excellent construction properties.

In response to the above-mentioned issues, the fire-resistant wooden structure of the present invention is a fire-resistant wooden structure used for the columns, beams, or walls of a building, and comprises a wooden structural core material that supports a load, a first covering material that covers the outer surface of the wooden structural core material, and a second covering material that covers the outer surface of the first covering material, characterized in that the first covering material contains organic fibers, free water, or crystallization water, and has a moisture content of 6.0% or more derived from free water or crystallization water, and the second covering material has a moisture content of 3.0% or less derived from free water or crystallization water.

Here, the bulk density of the second coating material is preferably 0.15 g/cm ³ or more and less than 0.70 g/cm ³ .

The fire-resistant wooden structure of the present invention is a fire-resistant wooden structure used for the columns, beams, or walls of a building, and comprises a wooden structural core material that supports a load, a first covering material that covers the outer surface of the wooden structural core material, and a second covering material that covers the outer surface of the first covering material, wherein the first covering material is made of slag gypsum board, and the second covering material is made of calcium silicate board.

It is desirable that the thickness of the first coating material be 10 mm or more and 30 mm or less, and that the thickness of the second coating material be 10 mm or more and 30 mm or less.

The fire-resistant wooden structure of the present invention is a fire-resistant wooden structure used for the columns, beams, or walls of a building, and comprises a wooden structural core material that supports a load, a first covering material that covers the outer surface of the wooden structural core material, and a second covering material that covers the outer surface of the first covering material, wherein the first covering material is made of a cemented wood wool board, and the second covering material is made of a calcium silicate board.

It is desirable that the thickness of the first coating material be 10 mm or more and 20 mm or less, and the thickness of the second coating material be 20 mm or more and 30 mm or less.

Here, it is desirable that the device further includes a surface material that covers the outer peripheral surface of the second covering material, the surface material being fixed to the first covering material and the second covering material by a fixing member, and the tip of the fixing member being positioned inside the first covering material so as not to penetrate the first covering material.

It is also desirable that the structure further includes a surface material that covers the outer surface of the second covering material, and that the surface material is fixed to the wooden structural core material by fixing members that penetrate the first covering material and the second covering material.

Furthermore, it is desirable that the thickness of the first coating material be three times or less the thickness of the second coating material. Alternatively, it is desirable that the thickness of the second coating material be three times or less the thickness of the first coating material. Alternatively, it is desirable that the first coating material have the same thickness as the second coating material.

In this way, in the fire-resistant wooden structure of the present invention, the first coating material covering the outer surface of the wooden structural core material contains organic fibers and has a moisture content of 6.0% or more derived from free water or crystallization water, and the second coating material covering the outer surface of the first coating material has a moisture content of 3.0% or less derived from free water or crystallization water. Furthermore, in the fire-resistant wooden structure of the present invention, the first coating material covering the outer surface of the wooden structural core material is made of slag gypsum board or wood wool cement board, and the second coating material is made of calcium silicate board.

As a result, the core material for a wooden structure is covered with the highly fire-resistant first and second covering materials in a layered structure. This improves the fire resistance of the fire-resistant wooden structure while ensuring excellent workability.

Here, the bulk density of the second covering material is 0.15 g/cm or ^more and ^less than 0.70 g/cm. This allows for further improvement in workability by using a second covering material that has a lower bulk density and is lighter than reinforced gypsum board.

The fire-resistant wooden structure also includes a surface material that covers the outer surface of the second covering material. The surface material is fixed to the first and second covering materials by fixing members, and the tips of the fixing members are positioned inside the first covering material so as not to penetrate the first covering material. This prevents the fixing members from becoming thermal bridges that carbonize the wooden structural core material in the event of a fire. This further improves the fire resistance of the fire-resistant wooden structure.

The surface material is fixed to the core material for wooden structures by fixing members that penetrate the first and second covering materials. This allows the fixing members to more firmly integrate the surface material, first and second covering materials, and core material for wooden structures.

Furthermore, the thickness of the first covering material is no more than three times the thickness of the second covering material, or the thickness of the second covering material is no more than three times the thickness of the first covering material, or the first covering material has the same thickness as the second covering material. In either case, this allows the core material for a wooden structure to be covered with highly fire-resistant materials to form a layered structure. Therefore, in either case, the fire resistance of the fire-resistant wooden structure can be further improved.

Furthermore, when the first covering material is a slag gypsum board and the second covering material is a calcium silicate board, the thickness of the first covering material is 10 mm to 30 mm, and the thickness of the second covering material is 10 mm to 30 mm. Also, when the first covering material is a wood wool cement board and the second covering material is a calcium silicate board, the thickness of the first covering material is 10 mm to 20 mm, and the thickness of the second covering material is 20 mm to 30 mm. In other words, by combining a non-flammable first covering material with a lightweight calcium silicate board within the above thickness ranges, both fire resistance and excellent workability can be ensured.

1 is a perspective view partially showing the inside of a fire-resistant wood structure according to an embodiment of the present invention. 1 is a cross-sectional view of a fire-resistant wood structure according to an embodiment of the present invention. 1A is a schematic enlarged cross-sectional view of a wood fireproof structure before heating, and FIG. 1B is a schematic enlarged cross-sectional view of the wood fireproof structure in the first stage during heating. 1A is a schematic enlarged cross-sectional view of a wood fireproof structure in a second stage during heating, and FIG. 1B is a schematic enlarged cross-sectional view of a wood fireproof structure in a third stage during heating. 10 is a graph showing the relationship between temperature change and thermal conductivity of each material. 1 is a graph showing the relationship between temperature change and linear shrinkage rate of each material. 1 is a graph showing the relationship between temperature change and apparent volumetric specific heat of each material. FIG. 1 is a diagram showing the relationship between the temperature rise of each material and the amount of heat required to raise the temperature. FIG. 1 is a diagram for explaining an outline of a test specimen used in a fire resistance experiment. 1 is a graph showing temperature changes in a heating furnace in a fire resistance experiment. 1 is a graph showing temperature changes at each measurement point of a test specimen in a fire resistance experiment.

Embodiments of the present invention will now be described with reference to the drawings. Figure 1 is a perspective view of a fire-resistant wooden structure according to an embodiment of the present invention, and Figure 2 is a cross-sectional view thereof.

As shown in Figure 1, the fire-resistant wooden structure 1 is a structure used for the columns, beams, or walls of a building, and comprises a wooden structural core material 10 that supports a load, a first covering material 11 that covers the outer surface of the wooden structural core material 10, a second covering material 12 that covers the outer surface of the first covering material 11, and a surface material 13 that covers the outer surface of the second covering material 12.

<Wooden structural core material>
The wooden structural core 10 is formed in the shape of a rectangular prism with four sides. The wooden structural core 10 is not limited to any particular tree species, and can be made of wood such as cedar, cypress, red pine, black pine, cypress, larch, Japanese cedar, Japanese cedar, Douglas fir, western hemlock, zelkova, chestnut, oak, Japanese oak, or beech. The wooden structural core 10 can be solid wood, laminated lumber, laminated veneer lumber, cross-laminated lumber, or ungraded lumber. The wooden structural core 10 can be made of commercially available or custom-made lumber.

The wooden structural core material 10 is not limited in density, but may have a density of 0.38±0.08 g/ ^cm3 or more. The wooden structural core material 10 contains moisture, and although there is no limit to the moisture content, the moisture content may be 15% or less. As shown in Figures 1 and 2, the wooden structural core material 10 may be a square timber with a rectangular cross section (e.g., 600 mm x 600 mm).

<First coating material>
The first covering material 11 is formed to have a cylindrical cross section so as to surround the four side surfaces of the wooden structural core material 10. As shown in Fig. 2, the first covering material 11 is composed of a plurality of plate-like members, each of which is fixed to each side surface of the wooden structural core material 10 by a first fastener 21 such as a screw. The first fastener 21 penetrates the first covering material 11 in the thickness direction, and its tip is inserted into the wooden structural core material 10. The first covering material 11 is formed, for example, from a slag gypsum board or a wood wool cement board.

<Slag gypsum board>
Slag gypsum board is a material classified as a fiber-reinforced cement board under JIS A5430. It contains slag, gypsum, and organic fibers, primarily waste paper. Specifically, slag gypsum board is a non-combustible material containing 1-5 wt% or less of organic fiber (waste paper), including 30-50 wt% granulated blast furnace slag, 30-50 wt% gypsum dihydrate, and 5 wt% or less of waste paper. Slag gypsum board is a material with high hardness even before heating and maintains the same hardness during heating. Because slag gypsum board contains highly tenacious organic fibers, cracking due to heating is extremely small, preventing damage. Furthermore, heat infiltration through cracks to the backside can be reduced.

The slag gypsum board contains free water and crystalline water, and has a bulk density of 0.90 g/cm ^{or more} and less than 1.20 g/cm. For example, a slag gypsum board stored in an environment of ²³ °C and 50% RH had ^{a bulk} density of 1.17 g/cm. The slag gypsum board has a moisture content derived from free water and crystalline water of about 13.2%, and the amount of free water and crystalline water is about 0.16 g/cm ( ^an example of a slag gypsum board stored in an environment of 23°C and 50% RH). The amount of free water and crystalline water contained in the slag gypsum board per volume is equal to or greater than that of reinforced gypsum board. In addition, in an example where the slag gypsum board was used as the first coating material, the maximum temperature reached by the slag gypsum board was about 300°C.

Here, crystallization water refers to water that is chemically bound to the material components in the slag gypsum board, and is different from water that is not chemically bound (free water). The gypsum in the slag gypsum board is gypsum dihydrate (CaSO ₄ ·2H ₂ O), just like the gypsum in reinforced gypsum board, and when heated, it releases moisture and becomes gypsum hemihydrate (CaSO ₄ ·½H ₂ O). When hemihydrate is heated, it releases moisture and becomes gypsum anhydrate (CaSO ₄ ). The crystallization water contained in the gypsum exhibits fire resistance, allowing it to be used as a fireproof material. The amount of moisture in the slag gypsum board was determined by the mass loss from room temperature to 200°C.

The gypsum and blast furnace slag contained in slag gypsum boards are by-products, and disposing of them as is would be an environmental burden, but using them in slag gypsum boards reduces that burden. Furthermore, the waste paper used in slag gypsum boards is also a recycled material. Because 87% of the material in slag gypsum boards is made from recycled materials, _CO2 emissions can be reduced.

<Wood cement board>
Wood wool cement board is a material classified as a wood-based cement board as defined in JIS A5404, and is a semi-non-combustible material that uses, for example, 100% domestically produced thinned cypress as the organic fiber. Specifically, wood wool cement board is a semi-non-combustible material that contains 1 to 30 wt% or less of organic fiber (wood wool), and contains 70 wt% or more of cement and 30 wt% or less of wood wool. Wood wool cement board is a material that has hardness even before heating, and maintains the same hardness during heating.

Because the wood wool cement board contains highly tough organic fibers, cracking due to heating is extremely small, enabling increased impact resistance. The wood wool cement board contains free water and crystalline water, and has a bulk density of 1.0 g/ ^cm3 or more; for example, a board stored in an environment of 23°C and 50% RH had a bulk density of 1.13 g/ ^cm3 . The wood wool cement board has a moisture content derived from free water and crystalline water of approximately 7.0%, and the amount of free water and crystalline water is approximately 0.08 g/ ^cm3 (an example of a board stored in an environment of 23°C and 50% RH). The moisture content of the wood wool cement board was determined by the mass loss from room temperature to 200°C. In one example, the maximum temperature reached by the wood wool cement board was approximately 300°C.

When using wood wool cement boards, the decomposition of crystalline water in the hardened cement paste occurs at around 450°C. However, when wood wool cement boards are used to cover the inside of calcium silicate boards, depending on the heating conditions, the wood wool cement board may not reach 450°C, and the decomposition of crystalline water may not occur.

The bulk density of reinforced gypsum board is about 0.75 to 0.95 g/cm ³ . For example, the bulk density of board stored in an environment of 23°C and 50% RH was 0.79 g/cm ³ .

<Second covering material>
The second covering material 12 is formed to have a cylindrical cross section so as to cover the outer peripheral surface of the first covering material 11. The second covering material 12 is formed of, for example, a calcium silicate plate.

As shown in FIG. 2, the second covering material 12 is composed of multiple plate-shaped members, each of which is fixed to the first covering material 11 by a second fastener 22 such as a screw. To firmly fasten the first covering material 11 and the second covering material 12 to the wooden structural core material 10, the second fastener 22 penetrates the second covering material 12 in the thickness direction and has its tip inserted into the first covering material 11. It is desirable that the second fastener 22 penetrates the first covering material 11 and the second covering material 12 in the thickness direction and is inserted into the wooden structural core material 10. It is desirable that the second fastener 22 be positioned at a distance of 30 mm or more from the corners of the wooden structural core material 10. It is preferable that the second fastener 22 be made of stainless steel, which has a lower thermal conductivity than iron.

<Calcium silicate board>
The calcium silicate board according to an embodiment of the present invention is a non-combustible material belonging to the xonotlite group, which exhibits minimal structural change due to heat shrinkage and high fire resistance and thermal insulation. It contains 65-80 wt% calcium silicate, less than 10 wt% calcium hydroxide, and less than 3 wt% crystalline silica (quartz). The calcium silicate board maintains low thermal conductivity over a wide temperature range, i.e., it is a highly insulating material, with a fire resistance temperature of approximately 1000°C. The calcium silicate board contains moisture and has a bulk density of 0.15 g/ ^cm3 or more but less than 0.70 g/ ^cm3 . For example, a board stored at 23°C and 50% RH had a bulk density of 0.30 g/ ^cm3 . Furthermore, the calcium silicate board has a moisture content of approximately 2.2% (less than 3.0%) derived from free water and crystalline water, and a moisture content of approximately 0.007 g/ ^cm3 (for an example of a board stored at 23°C and 50% RH). Since calcium silicate boards contain almost no water of crystallization, the weight loss due to drying at 105°C was taken as the amount of water.

<Surface material>
The surface material 13 is formed to have a cylindrical cross section so as to surround the second covering material 12. The surface material 13 may be formed, for example, from wood formed into a general board shape, and the material is not particularly limited. The surface of the surface material 13 may be coated with a paint that enhances weather resistance, durability, and aesthetics, as well as a boric acid or phosphoric acid agent. The boric acid or phosphoric acid agent releases moisture when heated, slowing the temperature rise of the present invention in the event of a fire and improving fire resistance.

The surface material 13 is fixed to the first covering material 11 and the second covering material 12 by third fasteners (fixing members) 23 such as screws. The tips of the third fasteners 23 are positioned inside the first covering material 11 so as not to penetrate the first covering material 11. In other words, the third fasteners 23 penetrate the surface material 13, the second covering material 12, and the first covering material 11 in that order in the thickness direction, and the tips do not reach the wooden structural core material 10.

Furthermore, when firmly fixing the first covering material 11 and the second covering material 12 to the wooden structural core material 10, it is desirable that the third fixing device 23 penetrate the first covering material 11 and the second covering material 12 and be inserted into the wooden structural core material 10. It is desirable that the third fixing device 23 be located, for example, at least 30 mm away from the corners of the wooden structural core material 10. It is desirable to use stainless steel as the material for the third fixing device 23, as it has a lower thermal conductivity than iron.

The third fixing device 23 may be fitted with a wooden plug 23a to hide the screw head, or non-combustible wood or a non-combustible material may be used instead of the wooden plug 23a. The wooden plug 23a, non-combustible wood, or non-combustible material fitted to the screw head in this way can reduce thermal bridges in the screws.

Here, the changes that occur as the wood fire-resistant structure 1 undergoes general heating during a fire or other event will be explained with reference to Figures 3 and 4. Figure 3(a) is a schematic enlarged cross-sectional view of the wood fire-resistant structure 1 before heating, Figure 3(b) is a schematic enlarged cross-sectional view of the wood fire-resistant structure in the first stage of heating, Figure 4(a) is a schematic enlarged cross-sectional view of the wood fire-resistant structure in the second stage of heating, and Figure 4(b) is a schematic enlarged cross-sectional view of the wood fire-resistant structure in the third stage of heating.

As shown in Figure 3(a), before heating, the first coating material 11 and surface material 13 contain a large amount of moisture W (see the circles in the figure). The second coating material 12, which is placed there for the purpose of heat insulation, contains almost no moisture. In the first stage of heating shown in Figure 3(b), the surface material 13, which is heated from the outside by a flame or the like, is carbonized, and the moisture in the heated first coating material 11 decreases.

In the second stage of heating shown in Figure 4(a), the carbonized surface material 13 is burned away, and the moisture content of the first coating material 11 heated through the second coating material 12 is further reduced. In the third stage of heating shown in Figure 4(b), the moisture content of the first coating material 11 heated through the second coating material 12 is further reduced. As long as the first coating material 11 retains free water and crystallized water, the first coating material 11 is believed to suppress the temperature rise of the wooden structural core material 10 and maintain the temperature below the carbonization temperature of the wood in the wooden structural core material 10 (approximately 260°C). Therefore, a high moisture content in the first coating material 11 is desirable. Even if the moisture content of the first coating material 11 and the second coating material 12 decreases as shown in Figure 4(b), they can still maintain their fire-resistant coating performance as insulating materials.

To improve the fire resistance of the wood fire-resistant structure 1, it is important that at least one of the first covering material 11 and the second covering material 12 has a high moisture content, in other words, that it is difficult for the temperature to rise. Below, we will compare and explain the materials that make up the first covering material 11 and the second covering material 12.

This section explains the thermal conductivity, linear shrinkage rate, apparent volumetric specific heat, and amount of heat required to raise the temperature of the slag gypsum board used in the first covering material 11 and the calcium silicate board used in the second covering material 12. Conventionally used reinforced gypsum board will also be explained for comparison.

Figure 5 is a graph showing the relationship between temperature and thermal conductivity for slag gypsum board, calcium silicate board, and reinforced gypsum board. The lower the thermal conductivity, the less heat is transferred, with calcium silicate board having the lowest thermal conductivity. For example, using calcium silicate board for the second coating material 12 is thought to have the effect of suppressing the inflow of heat into the interior.

Figure 6 is a graph showing the relationship between the temperature of slag gypsum board, calcium silicate board, and reinforced gypsum board and the linear shrinkage rate of the coating material due to heating. For each material, the linear shrinkage rate gradually increased with increasing temperature within the range from room temperature to approximately 600°C, and once the temperature exceeded 600°C, the linear shrinkage rate of reinforced gypsum board and slag gypsum board increased sharply.

The linear shrinkage rate is thought to affect the ease with which joints open and cracks occur, with calcium silicate board having the smallest linear shrinkage rate. Using calcium silicate board for the outer fire-resistant coating layer (second coating material 12), which is prone to high temperatures, is thought to have the effect of preventing heat from entering the interior due to joints opening and cracks.

Figure 7 is a graph showing the relationship between the temperature of slag gypsum board, calcium silicate board, and reinforced gypsum board and the apparent volumetric specific heat, which indicates how difficult it is to heat up. The apparent volumetric specific heat of reinforced gypsum board and slag gypsum board increased at approximately 100 to 200°C. This is thought to be due to the latent heat of vaporization of the crystalline water contained in the reinforced gypsum board and slag gypsum board.

The greater the amount of free water and crystalline water contained in slag gypsum board, reinforced gypsum board, and calcium silicate board, the greater the apparent volumetric specific heat, and the greater the apparent volumetric specific heat, the less likely it is that the temperature will rise. The target carbonization temperature for wood used as the wooden structural core material 10 is said to be approximately 260°C, but using slag gypsum board, which is less likely to rise in temperature in the range of approximately 100 to 200°C, as the inner first coating material 11 is thought to have the effect of lengthening the time it takes for the surface of the wooden structural core material 10 to reach the carbonization temperature.

Figure 8 shows the relationship between the temperature rise of slag gypsum board, calcium silicate board, and reinforced gypsum board and the amount of heat required to achieve that temperature rise. The temperature rise was calculated from the apparent volumetric specific heat for four ranges: 20°C to 260°C, 20°C to 300°C, 20°C to 400°C, and 20°C to 500°C.

As shown in Figure 8, it was confirmed that in all ranges, the amount of heat required to raise the temperature was greatest for slag gypsum board, followed by reinforced gypsum board and calcium silicate board. The greater the amount of heat required to raise the temperature, the more difficult it is to raise the temperature. In all temperature ranges shown in the graph, the amount of heat required to raise the temperature was greatest for slag gypsum board. This confirms that slag gypsum board is less likely to raise its temperature than reinforced gypsum board.

As such, in the fire-resistant wooden structure 1 according to this embodiment, the first coating material 11 covering the outer surface of the wooden structural core material 10 contains organic fibers, free water, or crystal water, and has a moisture content of 6.0% or more derived from free water or crystal water, while the second coating material 12 covering the outer surface of the first coating material 11 has a moisture content of 3.0% or less derived from free water or crystal water. Furthermore, the first coating material 11 is composed of either a slag gypsum board or a wood wool cement board, and the second coating material 12 is composed of a calcium silicate board.

As a result, the highly fire-resistant first covering material 11 and second covering material 12 surround the wooden structural core material 10 in a layered structure. This allows for the production of a fire-resistant wooden structure 1 that ensures excellent fire resistance and ease of construction.

Here, the bulk density of the second covering material 12 is 0.15 g/cm or ^more and less than 0.70 g/ ^cm . This allows for the use of a second covering material 12 that has a smaller bulk density and is lighter than reinforced gypsum board, thereby improving workability.

The fire-resistant wooden structure 1 also includes a surface material 13 that covers the outer surface of the second covering material 12. The surface material 13 is fixed to the first covering material 11 and the second covering material 12 by a third fixing device (fixing member) 23, and the tip of the third fixing device 23 is positioned inside the first covering material 11 so as not to penetrate the first covering material 11. This prevents the fixing member from becoming a thermal bridge that carbonizes the wooden structural core material in the event of a fire. This further improves the fire resistance of the fire-resistant wooden structure 1.

Furthermore, the surface material 13 is fixed to the wooden structural core material by a third fastener 23 that penetrates the first covering material 11 and the second covering material 12. As a result, the third fastener 23 integrates the surface material 13, the first covering material 11, the second covering material 12, and the wooden structural core material 10. This ensures the strength of the entire fire-resistant wooden structure.

Furthermore, the thickness of the first covering material 11 is no more than three times the thickness of the second covering material 12, or the thickness of the second covering material 12 is no more than three times the thickness of the first covering material 11, or the first covering material 11 has the same thickness as the second covering material 12. As a result, in either case, the wooden structural core material 10 can be covered with highly fire-resistant materials to form a layered structure. Therefore, in either case, the fire resistance of the wooden fire-resistant structure 1 can be further improved.

Furthermore, when the first coating material 11 is a slag gypsum board and the second coating material 12 is a calcium silicate board, the thickness of the first coating material 11 is 10 mm to 30 mm, and the thickness of the second coating material 12 is 10 mm to 30 mm. Also, when the first coating material 11 is a wood wool cement board and the second coating material 12 is a calcium silicate board, the thickness of the first coating material 11 is 10 mm to 20 mm, and the thickness of the second coating material 12 is 20 mm to 30 mm. In other words, by using the non-flammable first coating material 11 and the lightweight calcium silicate board together within the above thickness ranges, fire resistance and excellent workability can be ensured.

Next, a fire resistance experiment to confirm the fire resistance performance of the fire-resistant wooden structure 1 according to the embodiment will be described. The test specimen, a fire-resistant wooden structure 1, was placed in a heating furnace and heated for one hour according to the standard heating temperature curve. After that, the heating was stopped and the structure was allowed to cool for approximately 180 minutes (see Figure 10).

Measurement points for the wooden fire-resistant structure 1 were eight locations A1 to A8 inside the wooden fire-resistant structure 1, as shown in Figure 9. Specifically, corner temperatures were measured at four locations: A1, A3, A5, and A7, and flat surface temperatures were measured at four locations: A2, A4, A6, and A8.

The results of the fire resistance experiment are shown in Figure 11. The results show that the temperature of the fire-resistant wooden structure 1 was higher at the corners (A1, A3, A5, A7) than at the flat surfaces (A2, A4, A6, A8), and that the temperature was below 260°C, the target carbonization temperature of the wooden structural core material 10, at all measurement points. After the experiment, the covering material was removed and the condition of the wooden structural core material 10 was checked. No carbonization of the wooden structural core material 10 was observed, confirming that the present invention has fire resistance.
<Test specimen specifications>
・Wooden structural core material (laminated wood), 600mm x 600mm
- Slag gypsum board, thickness 12 mm
Calcium silicate board, 30 mm thick
- Surface material (laminated wood), thickness 18mm

Example 1
An element test specimen of a fire-resistant wooden structure 1 was fabricated by arranging a wooden structural core material 10, a first covering material 11, and a second covering material 12 in this order from the inside. A slag gypsum board was used for the first covering material 11, and a calcium silicate board was used for the second covering material 12.
<Test specimen specifications>
- Core wood for wooden structures (lumber), thickness 60 mm
- Slag gypsum board, thickness 30 mm
Calcium silicate board, 10 mm thick

(Examples 2 and 3)
Examples 2 and 3 are the same as Example 1 except for the thicknesses of the first covering material 11 and the second covering material 12. Specifically, Example 2 used a 20 mm thick slag gypsum board for the first covering material 11 and a 20 mm thick calcium silicate board for the second covering material 12. Example 3 used a 10 mm thick slag gypsum board for the first covering material 11 and a 30 mm thick calcium silicate board for the second covering material 12.

(Comparative Examples 1 to 4)
In Comparative Example 1, only a 40 mm thick slag gypsum board was used. In Comparative Example 2, only a 40 mm thick calcium silicate board was used. In Comparative Example 3, a 20 mm thick calcium silicate board was used for the first covering material 11, and a 20 mm thick slag gypsum board was used for the second covering material 12. In Comparative Example 4, only a 40 mm thick reinforced gypsum board was used.

(Examples 4 and 5)
Next, examples and comparative examples of a fireproof wooden structure 1 in which the first covering material 11 is made of a cemented wood board and the second covering material 12 is made of a calcium silicate board will be described. In examples 4 and 5, elemental test specimens of the fireproof wooden structure 1 were prepared by arranging the wooden structural core material 10, the first covering material 11, and the second covering material 12 in this order from the inside to outside. A cemented wood board was used for the first covering material 11, and a calcium silicate board was used for the second covering material 12.
<Test specimen specifications>
- Core wood for wooden structures (lumber), thickness 60 mm
・Wood cement board ・Calcium silicate board

In Example 4, a 20 mm thick wood wool cement board was used, and a 20 mm thick calcium silicate board was also used. In Example 5, a 10 mm thick wood wool cement board was used, and a 30 mm thick calcium silicate board was also used.

(Comparative Example 5)
Only a 40 mm thick wood wool cement board was used in Comparative Example 5. The experimental conditions for Examples 1 to 5 and Comparative Examples 1 to 5 are as shown in Table 1.

<Evaluation>
In Examples 1 to 5 and Comparative Examples 1 to 5, the wood was heated in a small electric furnace, and the time elapsed until the surface temperature of the wood reached 260°C was measured. In addition, the workability was evaluated based on the weight of the entire wood fire-resistant structure 1. The evaluation results are shown in Table 1.

The results showed that Examples 1 to 3 took longer for the surface temperature to reach 260°C than Comparative Examples 1 to 5. In particular, Examples 1 and 2 took longer for the surface temperature to reach 260°C than the other Examples and Comparative Examples 1 to 4. Furthermore, by combining calcium silicate boards, weight can be reduced, thereby improving workability.

As such, Examples 1 to 3, in which the fire-resistant covering material on the inside of the wood fire-resistant structure 1 was a slag gypsum board and the fire-resistant covering material on the outside was a calcium silicate board, received an overall rating of ◯. Compared to Comparative Examples 1 to 5, which received an overall rating of ×, it was confirmed that they met both fire resistance performance and workability requirements.

In Examples 4-5, it took a longer time for the surface temperature to reach 260°C than in Comparative Examples 2-5. Furthermore, by combining calcium silicate boards, weight can be reduced, improving workability. Note that in Comparative Example 1, the time it took for the surface temperature to reach 260°C was longer than in Examples 4-5, but because it was constructed solely from slag gypsum boards, it was difficult to reduce weight, resulting in poor workability.

As such, Examples 4 and 5, in which the fire-resistant covering material on the inside of the wood fire-resistant structure 1 was a cemented wood board and the fire-resistant covering material on the outside was a calcium silicate board, received an overall rating of ◯. Compared to Comparative Examples 1 to 5, which received an overall rating of ×, it was confirmed that they met both fire resistance performance and workability requirements.

Embodiments of the present invention have been described in detail above with reference to the drawings, but the specific configurations are not limited to these embodiments, and design changes that do not deviate from the gist of the present invention are included in the present invention.

For example, in the above embodiment, the fixing of the wooden structural core material 10 to the first covering material 11, the fixing of the first covering material 11 to the second covering material 12, and the fixing of the second covering material 12 to the surface material 13 may all be done using screws only, adhesive only, or a combination of screws and adhesive.

In addition, in the above embodiment, the first covering material 11, the second covering material 12, and the surface material 13 are all configured from a single layer of plate-like material, but each may be configured by stacking multiple plate-like materials in the thickness direction. Furthermore, the first covering material 11 and the second covering material 12 may each be configured as a single layer or multiple layers. Specifically, the second covering material 12, which is arranged to cover the periphery of the first covering material 11, may be further covered with the first covering material 11, or the periphery of the first covering material 11 may be further covered with the second covering material 12. Furthermore, the wooden structural core material 10 may be coated with a paint to increase durability.

1: Wooden fire-resistant structure 10: Wooden structural core material 11: First covering material 12: Second covering material 13: Surface material

Claims (10)

A fire-resistant wooden structure used for the columns, beams or walls of a building,
a wooden structural core material that supports a load;
a first covering material that covers the outer peripheral surface of the core material for wooden structure;
a second coating material that covers an outer peripheral surface of the first coating material,
The first covering material is made of a slag gypsum board,
A fire-resistant wooden structure, wherein the second covering material is made of a calcium silicate board. A fire-resistant wooden structure used for the columns, beams or walls of a building,
a wooden structural core material that supports a load;
a first covering material that covers the outer peripheral surface of the core material for wooden structure;
a second coating material that covers an outer peripheral surface of the first coating material,
the first covering material is made of a wood wool cement board,
A fire-resistant wooden structure, wherein the second covering material is made of a calcium silicate board. Further provided is a surface material that covers an outer peripheral surface of the second coating material,
the surface material is fixed to the first covering material and the second covering material by a fixing member;
3. A wood fire-resistant structure according to claim 1 , wherein the tip of the fixing member is arranged inside the first covering material so as not to penetrate the first covering material. Further provided is a surface material that covers an outer peripheral surface of the second coating material,
3. The fire-resistant wooden structure according to claim 1 , wherein the surface material is fixed to the core material for the wooden structure by a fixing member that penetrates the first covering material and the second covering material. 3. The fire-resistant wood structure according to claim 1 , wherein the thickness of the first covering material is three times or less the thickness of the second covering material. 3. The wood fire-resistant structure according to claim 1 , wherein the thickness of the second covering material is three times or less the thickness of the first covering material. 3. The fire-resistant wood structure according to claim 1, wherein the first covering material has the same thickness as the second covering material. 3. The fire-resistant wooden structure according to claim 1, wherein the bulk density of the second covering material is equal to or greater than 0.15 g/cm ^<3> and less than 0.70 g/cm ^<3> . The thickness of the first coating material is 10 mm or more and 30 mm or less,
2. The fire-resistant wooden structure according to claim 1 , wherein the thickness of the second covering material is 10 mm or more and 30 mm or less. The thickness of the first coating material is 10 mm or more and 20 mm or less,
3. The fire-resistant wooden structure according to claim 2 , wherein the thickness of the second covering material is 20 mm or more and 30 mm or less.