Wooden fire-resistant member

Abstract

To reduce the risk of a gap between ALC members caused by thermal shrinkage and thermal deformation occurring in a fireproof covering part in a membrane type woody fireproof member using lightweight foamed concrete (ALC) as a main material of the fire-resistant covering part.SOLUTION: A wooden fire-resistant member 10 has a fire-resistant coating part 2 having a multilayer structure in which an outer layer 23 formed of fire-resistant lightweight cellular concrete having a xonotlite generation rate of 35% or more and inner layers 21 and 22 formed of calcium silicate or gypsum are laminated, wherein the thickness of the outer layer 23 is 35 mm or more and 150 mm or less, the thickness of the inner layers 21 and 22 is 1 / 10 or more and 3 / 10 or less of the thickness of the outer layer 23, and the fire-resistant coating part 2 has an air layer 5 which is a belt-like through-hole narrower than the width of each side face of the load support part 1 and penetrates the inside of the fire-resistant coating part 2 in parallel with each side face and along the longitudinal direction of the load support part 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fire-resistant wood component. More specifically, the present invention relates to a membrane-type fire-resistant wood component in which a load-bearing wood component is covered with a fire-resistant covering, and the fire-resistant covering is mainly made of lightweight aerated concrete (ALC). [Background technology]

[0002] The "Act on Promotion of the Use of Wood in Public Buildings, etc." came into effect in 2010. The purpose of this law is to "promote the use of wood in public buildings, etc., in light of the fact that promoting the use of wood contributes to the prevention of global warming, the creation of a recycling-oriented society, the conservation of national land where forests exist, the realization of multiple functions such as water resource conservation, and the revitalization of the economies of mountain villages and other regions," and as a result, momentum is building to promote the use of wood in buildings.

[0003] On the other hand, when wood, which is combustible, is used as a structural member of a building, it is required to have a certain level of fire resistance, specifically, to prevent the collapse of the building due to carbonization or combustion of the structural frame for a certain period of time after the start of a fire. Therefore, various types of fire-resistant wooden members have been developed as building materials to provide such fire resistance to wooden buildings.

[0004] There are three types of fire-resistant wooden members: a "fire-stop type" in which a fire-stop layer and a substitute fire layer are laminated around the load-bearing part, a "hybrid type" in which a reinforcing steel frame is placed inside the wooden member, and a "membrane type" in which the load-bearing wooden member is covered with a fire-resistant covering made of a heat insulating material or the like (see Non-Patent Document 1).Of these, membrane-type fire-resistant wooden members have a fire-resistant covering made of gypsum board or calcium silicate board (see Patent Documents 1 and 2).

[0005] In recent years, it has also been proposed to use lightweight aerated concrete (ALC) as the main material for the fire-resistant covering of the membrane-type wood fire-resistant component described above, with a portion of the outer layer being made of the same (see Patent Document 3). ALC contains air bubbles and pores internally, and has the properties of being extremely lightweight with a bone-dry bulk density of approximately 0.5, while also having relatively high strength per weight. Furthermore, compared to other cement-based components, ALC has relatively low thermal conductivity and excellent fire resistance. Therefore, in the field of wood fire-resistant components, it is expected that demand for membrane-type wood fire-resistant components using lightweight aerated concrete as the main material for the fire-resistant covering will increase in the future.

[0006] However, while ALC, a widely available building material, is a cement-based component with relatively excellent heat resistance, there is a risk of gaps forming between ALC components at joints (where ALC components meet) and corners due to thermal shrinkage or deformation under the heating conditions expected during a fire. If such gaps were to form in the fire-resistant coating covering the load-bearing parts, heat could penetrate through the gaps and cause the load-bearing parts to burn or char in a shorter time than expected. Therefore, there was a need for a membrane-type wood fire-resistant component that uses lightweight aerated concrete as the main material for the fire-resistant coating, to reduce the risk of gaps forming between components due to ALC thermal shrinkage, thereby further improving the reliability of wood fire-resistant components. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-46286 [Patent Document 2] Japanese Patent Application Publication No. 2018-21407 [Patent Document 3] Japanese Patent Publication No. 2022-114965 [Non-patent literature]

[0008] [Non-Patent Document 1] Ministry of Land, Infrastructure, Transport and Tourism website: "Document 3: Compilation and comparison of technical methods for fire-resistant structures using wood" [Retrieved August 4, 2023]<URL:https: / / www.mlit.go.jp / common / 000184155.pdf> Summary of the Invention [Problem to be solved by the invention]

[0009] The purpose of the present invention is to reduce the risk of gaps occurring in the fire-resistant coating between membrane-type wood fire-resistant components that use lightweight aerated concrete (ALC) as the main material for the fire-resistant coating due to thermal shrinkage and thermal deformation. [Means for solving the problem]

[0010] The inventors of the present invention have come up with the idea that the above-mentioned problems can be solved by limiting the ALC forming the fire-resistant covering to "fire-resistant lightweight cellular concrete (fire-resistant ALC)," which has excellent fire resistance, and by forming an air layer that penetrates the fire-resistant covering inside the fire-resistant covering made of "fire-resistant ALC." Specifically, the present invention provides the following.

[0011] (1) A membrane-type wood fire-resistant component having a load-bearing portion that is a rectangular wooden component, a fire-resistant coating portion that covers all sides of the load-bearing portion, and an exterior coating layer that is a wooden or resin component that covers the outer surface of the fire-resistant coating portion, wherein the fire-resistant coating portion has a multi-layer structure consisting of an outer layer formed of fire-resistant lightweight aerated concrete with a zonolite production rate of 35% or more and an inner layer formed of calcium silicate or gypsum, the thickness of the outer layer being 35 mm or more and 150 mm or less, and the thickness of the inner layer being 1 / 10 or more and 3 / 10 or less of the thickness of the outer layer, and the fire-resistant coating portion has band-shaped through-holes that are narrower than the width of each side of the load-bearing portion and have air spaces that penetrate the interior of the fire-resistant coating portion parallel to each side and along the longitudinal direction of the load-bearing portion.

[0012] According to the wood fireproof member (1), the ALC used in the fireproof member, which is placed between a load-bearing wooden member and a wood or resin exterior coating, is expected to heat up quickly during a fire. The ALC is limited to "fire-resistant lightweight cellular concrete (fire-resistant ALC)," which has excellent fire resistance. Furthermore, an air gap is formed inside the fireproof member, which is made of "fire-resistant ALC." This ensures a heat dissipation path during heating, slowing the temperature rise of the ALC and allowing it to cool quickly after heating has ended. This reduces the risk of gaps between the ALC members due to thermal shrinkage and thermal deformation in membrane-type wood fireproof members that use lightweight cellular concrete (ALC) as the main material for the fireproof member.

[0013] (2) A wood fire-resistant member as described in (1), wherein the width of the air layer is between 1 / 4 and 1 / 2 of the width of each side surface, and the thickness of the air layer is between 1 / 15 and 1 / 2 of the thickness of the fire-resistant coating portion.

[0014] The fire-resistant wood component (2) can achieve high levels of both strength and fire resistance of the fire-resistant covering by optimizing the width and thickness of the air gap, allowing the above-mentioned effects of the fire-resistant wood component (1) to be enjoyed more stably and in a more preferable manner. [Effects of the Invention]

[0015] According to the present invention, in a membrane-type wood fire-resistant component that uses lightweight aerated concrete (ALC) as the main material of the fire-resistant coating, the risk of gaps between the ALC components occurring in the fire-resistant coating due to thermal shrinkage or thermal deformation can be reduced. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of a fire-resistant wood member of the present invention (a cross-sectional view of a section perpendicular to the longitudinal direction of the member). DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

[0018] <Wood fire-resistant materials> A fireproof wood member 10, which is one preferred embodiment of the fireproof wood member of the present invention, is a building material that can be used as structural members such as columns and beams in fire-resistant wooden buildings. The fireproof wood member 10 is a so-called membrane-type fireproof wood member. Specifically, as shown in Fig. 1, the fireproof wood member 10 has a load-bearing portion 1 that is a rectangular columnar wooden member, a fire-resistant coating portion 2 that covers all sides of the load-bearing portion 1 and is made of a fire-resistant material, and an exterior coating layer 3 that covers the outer peripheral surface of the fire-resistant coating portion.

[0019] The main features of this wood fire-resistant member 10 are that the main part of the fire-resistant coating portion 2 is formed from an improved ALC (referred to in this specification as "fire-resistant lightweight aerated concrete (ALC)") which has excellent fire resistance and a zonolite production rate of 35% or more, and that an air layer 5, which is a band-shaped hollow portion, is formed through the interior of the fire-resistant coating portion 2.

[0020] [Load support part] The load-bearing portion 1 is the core material of the membrane-type wood fire-resistant member 10, and is a wooden member in the shape of a rectangular pillar, preferably a square pillar. The load-bearing portion 1 receives and supports the load of the roof and floor. Materials that can be used for the load-bearing portion 1 include, without particular limitation, glued laminated lumber, laminated veneer lumber, sawn lumber, and solid wood. However, using glued laminated lumber, laminated veneer lumber, and sawn lumber, whose structural grades are specified by JAS, as building structural members makes structural calculations easier, so it is preferable to use any of the above wood materials: glued laminated lumber, laminated veneer lumber, and sawn lumber.

[0021] (corner protection) As shown in Figure 1, corner protection 6 is preferably provided at each corner of the load-bearing part 1. When the load-bearing part 1 is heated, the corners of the cross section of the component tend to heat up more easily than other parts because they are heated from two sides. Therefore, if exposed to high temperatures due to a fire or other event, carbonization often occurs in these areas, making it difficult to maintain bearing capacity for a long period of time. Chamfering the corners of the load-bearing part 1 to provide corner protection 6 can prevent premature carbonization of the corners of the load-bearing part 1. While the corner protection 6 may be a hollow air space, it is more preferable to use a structure filled with a filler containing a large amount of water of crystallization, such as gypsum. This structure effectively prevents premature carbonization of the corners of the load-bearing part 1 by absorbing heat caused by the evaporation of water of crystallization during heating. Specific examples of fillers containing a large amount of water of crystallization include calcium sulfate, aluminum hydroxide, and kaolinite.

[0022] [Fireproof coating] The fire-resistant coating 2 is laminated in a manner that covers all side surfaces of the load-bearing portion 1. As shown in Fig. 1, the fire-resistant coating 2 has a configuration in which some layers (inner layers 21, 22 of the fire-resistant coating) on ​​the inner layer side (a part near the surface that contacts the side surface of the load-bearing portion 1) are formed from calcium silicate or gypsum, and an outer layer side (another part near the surface of the load-bearing portion 1) layer (outer layer 23 of the fire-resistant coating) that accounts for 7 / 10 or more of the total thickness of the fire-resistant coating 2 is formed from "fire-resistant ALC".

[0023] In the wood fire-resistant component 10, ALC with a zonolite production rate of 35% or more ("fire-resistant lightweight aerated concrete (ALC)") is used as the ALC that accounts for at least 7 / 10 of the total thickness of the fire-resistant coating portion 2 in terms of thickness ratio. Here, in this specification, the "zonolite production rate (%)" of ALC refers to a value that can be calculated using the following formula (see Patent Publication No. 275547): Xonotlite formation rate (%) = {B / (MA)} / {18 / (714-18)} x 100 where M (mg) is the initial mass, A (mg) is the thermal mass measured at a heating rate of 20°C / min up to 1000°C using a differential thermal gravimetric analyzer (TG-DTA), and B (mg) is the thermal mass loss measured at a heating rate of 20°C / min from 750°C to 850°C using a differential thermal gravimetric analyzer (TG-DTA).

[0024] ALC with a zonolite production rate of 35% or more can be obtained, for example, by the manufacturing method disclosed in Japanese Patent No. 275547, specifically, by a manufacturing method in which the CaO / SiO2 molar ratio in the raw material mixture of ALC is set to a range of 1.1 to 0.7, and the Al / Si+Al atomic ratio in the raw materials is set to 7% or less, and then a prehydration treatment is performed on the siliceous raw materials and Portland cement prior to steam curing of the slurry.

[0025] Conventional ALC is primarily composed of a calcium silicate mineral called tobermorite (5CaO 6SiO2 5H2O), which contains five molecules of crystal water. This causes ALC to shrink by approximately 2% upon heating up to 700°C. Xonotlite (6CaO 6SiO2 H2O) contains only one molecule of crystal water, less than tobermorite. Therefore, compared to tobermorite, xonotlite experiences less dimensional change due to crystal decomposition caused by thermal dehydration. In other words, the superior heat resistance of "ALC with a zonolite formation rate of 35% or more" is due to the properties of the xonotlite crystal.

[0026] In the fire-resistant wood component 10, by using "fire-resistant ALC" with a zonolite generation rate of 35% or more as the ALC that accounts for 7 / 10 or more of the total thickness of the fire-resistant coating 2 in terms of thickness ratio, it is possible to extremely reduce the thermal shrinkage rate from room temperature to 750°C. This makes it possible to more reliably prevent a decrease in the fire resistance performance of the fire-resistant wood component 10 due to thermal shrinkage of the fire-resistant coating 2 that covers the load-bearing part 1.

[0027] The fire-resistant covering 2 has an outer layer 23 made of "fire-resistant ALC" with a thickness of 35 mm to 150 mm, and the thickness of the inner layers 21, 22 made of calcium silicate or gypsum (total thickness of both layers 21, 22) is between 1 / 10 and 3 / 10 of the thickness of the outer layer 23. By making the main part of the fire-resistant covering 2 (the part with a thickness ratio of 7 / 10 or more) out of "fire-resistant ALC," the water resistance of the fire-resistant covering 2 can be improved and the waterproofing performance that prevents moisture from entering the load-bearing part 1 can be enhanced compared to conventional membrane-type wood fire-resistant coverings made of gypsum board or calcium silicate board (calcium silicate board).

[0028] Furthermore, by optimizing the thickness ratio between the outer layer 23 formed from "fire-resistant ALC" and the inner layers 21, 22 formed from calcium silicate or the like, it is possible to achieve both economy in terms of component production costs and design related to the cross section of the component, so that the effects of the present invention related to fire resistance can be enjoyed more economically while also taking design into consideration.

[0029] Furthermore, the density (bulk density) of the gypsum is 0.75 to 0.95 g / cm 3 and the density of calcium silicate is 0.6 to 0.9 g / cm 3 whereas the density (bulk density) of ALC ("fire-resistant ALC") is 0.45 to 0.55 g / cm 3 Therefore, by making the fire-resistant covering 2 have the above-mentioned multi-layer structure, it is possible to make a member that has fire resistance equal to or greater than that of the conventional membrane-type wood fire-resistant member described above, in which the fire-resistant covering is made of gypsum board or the like, while also being lighter in weight.

[0030] Furthermore, in the wood fire-resistant component 10, the fire-resistant coating 2 has a multi-layer structure consisting of an outer layer 23 made of "fire-resistant ALC" and inner layers 21, 22 made of calcium silicate or gypsum laminated together. Therefore, even if the "fire-resistant ALC" is slightly warped due to heating during a fire or the like, the board material made of calcium silicate or gypsum that forms the inner layers 21, 22 will contribute to maintaining fire resistance, especially at corners, for a longer period of time.

[0031] Furthermore, because the fire-resistant covering 2 has a multi-layer structure, simple processing of some of the layers makes it easy to form the air layer 5, which is a cavity that penetrates the interior of the fire-resistant covering 2. Furthermore, the surface of the fire-resistant wood component 10 can be smoothed using the calcium silicate or gypsum boards that form the inner layers 21 and 22, which also improves the installation accuracy of the ALC panel that forms the outer layer 23.

[0032] The method of fixing each plate material (ALC panel, calcium silicate board, etc.) that makes up the fire-resistant covering 2 (inner layers 21, 22 and outer layer 23) to the load-bearing part 1 is preferably to use fixing screws 4. This makes it easier to replace each plate material individually and check for damage during installation work and maintenance work in the event of damage to the fire-resistant covering 2 due to an earthquake, fire, etc. Furthermore, it is preferable to apply a heat-shielding treatment to the fixing screws 4 to prevent them from becoming thermal bridges that transfer heat to the load-bearing part 1.

[0033] (air layer) As shown in FIG. 1 , the wood fireproof component 10 has an air layer 5, which is a hollow portion penetrating the interior of the fireproof covering 2 and is a strip-shaped through-hole with a width narrower than the width of each side surface of the load-bearing component 1. The air layer 5 is a hollow space (gap) formed inside the fireproof covering 2. The air layer 5 is formed on all side surfaces 11 of the load-bearing component 1, parallel to each side surface 11 and along the longitudinal direction of the load-bearing component 1. By forming the air layer 5 penetrating the fireproof covering 2 made of fire-resistant ALC, a heat dissipation path is secured during heating, delaying the temperature rise of the ALC and allowing the temperature to drop quickly after heating is completed. This reduces the risk of gaps between ALC components due to thermal shrinkage and thermal deformation in a membrane-type wood fireproof component using lightweight aerated concrete (ALC) as the main material for the fireproof covering.

[0034] In the wood fire-resistant member 10 shown in Figure 1, of the inner layers 21, 22 and outer layer 23 that make up the fire-resistant covering portion 2, an air layer 5 is formed inside the inner layer 22, which is made of calcium silicate board (a board material mainly made of calcium silicate) or the like, but the air layer 5 can also be formed inside the outer layer 23.

[0035] Furthermore, it is preferable that the width of the air layer 5 is between ¼ and ½ of the width of each side surface 11 of the load-bearing portion 1, and that the thickness of the air layer 5 is between ½ and 1 / 15 of the thickness of the fire-resistant covering portion 2. By setting the width and thickness of the air layer 5 to be within the above ranges, in a membrane-type wood fire-resistant component 10 using lightweight aerated concrete (ALC) as the main material of the fire-resistant covering portion 2, the fire-resistant covering portion 2 can stably exhibit the effect of reducing the risk of gaps between the ALC members due to thermal shrinkage and thermal deformation. Furthermore, by keeping the width and thickness of the air layer 5 within the above ranges, the physical strength of the fire-resistant covering portion 2 can be maintained within a preferable strength range. In other words, the above configuration can achieve both high levels of fire resistance and physical durability.

[0036] [Exterior coating layer] The exterior covering layer 3 is disposed on the outer peripheral surface of the fire-resistant covering part 2, and is exposed on the outermost surface of the fire-resistant wood component 10 to impart a design that gives the fire-resistant wood component 10 a wooden appearance. The exterior covering layer 3 can be made of a wooden finishing material such as laminated wood, other wood materials, laminated veneer lumber, lumber, plywood, or solid wood, or a resin sheet material for building components printed with a wood grain pattern. [Explanation of symbols]

[0037] 1 Load support part 11 Side of load bearing part 2 Fireproof coating 21, 22 inner layer 23 Outer layer 3. Exterior coating layer 4 Fixing screws 5 Air layer 6 Corner protection 10. Wood fire-resistant materials

Claims

1. a load-bearing portion that is a rectangular wooden member; a fire-resistant covering portion covering all sides of the load-bearing portion; An exterior coating layer that is a wood or resin member and covers the outer peripheral surface of the fire-resistant coating portion. A membrane-type wood fire-resistant member, The fire-resistant covering portion has a multi-layer structure in which an outer layer formed of fire-resistant lightweight cellular concrete having a zonolite production rate of 35% or more and an inner layer formed of calcium silicate or gypsum are laminated, the thickness of the outer layer being 35 mm or more and 150 mm or less, and the thickness of the inner layer being 1 / 10 or more and 3 / 10 or less of the thickness of the outer layer, The fire-resistant covering portion has a band-shaped through-hole having a width narrower than the width of each side surface of the load-supporting portion, and an air layer penetrating the inside of the fire-resistant covering portion in parallel with each side surface and along the longitudinal direction of the load-supporting portion. Wood fire-resistant components.

2. The width of the air layer is 1 / 4 or more and 1 / 2 or less of the width of each side surface, and the thickness of the air layer is 1 / 15 or more and 1 / 2 or less of the thickness of the fire-resistant covering portion, The fire-resistant wood member according to claim 1.

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