JP2022112906A - Fire resistant structure material and red-heat suppression method - Google Patents

Abstract

To provide a fire resistant structure material and a red-heat suppression method that can prevent the fire resistant structure material from being red-heat.SOLUTION: A fire resistant structure material 1A comprises a wooden or steel load support part 11a, a fire resistant coating layer 12a that coats the load support part 11a and is made of pure wood, and a burnable coating layer 13a that coats the fire resistant coating layer 12a, is made of pure wood and has a thickness less than 25 mm, and when being exposed to flame, it is burned and destroyed by fire. When conducting a burning test for 60 minutes by using standard heating according to ISO834-1 on the fire resistant structure material 1A and a comparison structure material in which the burnable coating layer 13a of the fire resistant structure material 1A is replaced with the fire resistant coating layer 12a, it is preferable that a mass decreasing rate of the fire resistant structure material 1A is larger than that of the comparison structure material just after the end of heating, and a mass decreasing rate of the fire resistant structure material is smaller than that of the comparison structure material within 180 minutes after the end of heating.SELECTED DRAWING: Figure 1

Description

The present invention relates to a refractory structural material and a red heat suppression method.

As a fire-resistant structural material, there is known a hybrid laminated lumber that has been certified by the Minister of Land, Infrastructure, Transport and Tourism as a one-hour fire-resistant structural column by the Japan Laminated Timber Industry Cooperative Association. The hybrid laminated timber has a structure in which a steel frame is covered with a solid wood laminated timber that does not use inorganic material or chemical impregnation. H-shaped steel is used as the steel frame. The tree species of the wood constituting the laminated lumber is Japanese larch or Douglas fir. In hybrid laminated lumber, one-hour fire resistance performance is realized by improving the fire-stopping effect of wood by taking advantage of the thermal conductivity of H-shaped steel and the heat absorption due to the influence of heat capacity.

In addition, various techniques have been proposed to obtain fire-resistant members by providing a burning margin on the surface of wood or a composite material of wood and other materials. A structural member has been proposed that includes a flammable layer of wood having a lower thermal inertia than the load-bearing layer and positioned outside the load-bearing layer. Further, in Patent Document 2, a load-bearing layer, a flame-stopping layer having a heat insulating material arranged outside the load-bearing layer, and a fire-stopping layer arranged outside the flame-stopping layer and made of wood having a predetermined thickness are disclosed. Structural materials have been proposed that include a flammable layer.

JP-A-2005-36457 JP 2005-48585 A

In general, it is difficult to stably achieve one-hour fire resistance performance with laminated solid wood. Specifically, when the solid wood laminated lumber is left to cool after heating, red heat may remain on the surface layer of the laminated solid wood, and combustion may continue. In the hybrid laminated lumber, the larch or Douglas fir that constitutes the laminated lumber is a tree species that is easy to stop burning, and the H-shaped steel suppresses the temperature rise of the wood covering the H-shaped steel. , 1 hour fire resistance is considered to be achieved. The shape of the H-shaped steel is also considered to contribute to the one-hour fire resistance performance. Specifically, in the above-mentioned hybrid laminated lumber, the web portion of the H-section steel is positioned at the central portion of the cross section of the laminated lumber, and the flange portion of the H-section steel is positioned at the outer peripheral portion of the cross section. As heat flows from the flange portion to the web portion, the heat flows from the outer peripheral portion to the inner portion where the temperature rises slowly.

On the other hand, when a square steel pipe is used as the steel frame of the hybrid laminated lumber, the square steel pipe has a shape that tends to increase in temperature over the entire surface. not done.
In Patent Literatures 1 and 2, no consideration is given to achieving one-hour fire resistance performance when square steel pipes are used, and there is room for improvement in fire resistance performance.

The inventors of the present invention conducted extensive research on the reason why red heat remains in the above-mentioned laminated solid wood timber. Cracks may occur in the carbonized layer, or a part of the carbonized layer may be missing, forming unevenness on the surface of the carbonized layer. , it was found that red heat remains inside the carbonized layer and combustion continues.

An object of the present invention is to provide a refractory structural material and a method for suppressing red heat, which can suppress red heat of the refractory structural material.

The present invention comprises a load-bearing part made of wood or steel, a refractory coating layer made of solid wood covering said load-bearing part, and a refractory coating layer covering said refractory coating layer, which burns and burns when exposed to fire. and a burnt-resistant coating layer made of solid wood and having a thickness of less than 25 mm.

The present invention also provides a structural material having a wooden or steel load-bearing part and a refractory coating layer covering the load-bearing part and made of solid wood, which burns and burns down when exposed to fire. A method for suppressing red heat by coating with a burnable coating layer made of wood to prevent cracks from occurring on the surface of the fireproof coating layer and suppress red heat of the fireproof coating layer, wherein the burnable coating layer is To provide a method for suppressing red heat, wherein the thickness is less than 25 mm.

ADVANTAGE OF THE INVENTION According to this invention, the fire-resistant structural material and red-heat suppression method which can suppress that a fire-resistant structural material red-heats can be provided.

FIG. 1 is a cross-sectional view schematically showing a fireproof structural material of a preferred embodiment of the present invention. FIG. 2 is a diagram showing measurement positions of temperature change when a combustion test is performed on the fireproof structural material of Example 1. FIG. FIG. 3 is a diagram showing measurement positions of temperature change when a combustion test is performed on the fireproof structural material of Example 2. FIG. FIG. 4 is a diagram showing measurement positions of temperature change when a combustion test is performed on the refractory structural material of Comparative Example 1. FIG. 5(a) to 5(c) are graphs showing the results of a combustion test of the refractory structural material of Example 1 and measurement of the temperature of the refractory structural material. FIGS. 6(a) to 6(d) are graphs showing the results of the temperature measurement of the refractory structural material of Example 2, which was subjected to a combustion test. 7(a) to (c) are graphs showing the results of the temperature measurement of the refractory structural material of Comparative Example 1, which was subjected to a combustion test. FIG. 8 is a photograph showing the state of the refractory structural material of Example 1 after the combustion test. FIG. 9 is a photograph showing the state of the refractory structural material of Example 2 after the combustion test. 10 is a photograph showing the state of the refractory structural material of Comparative Example 1 after the combustion test. FIG. 11 is a graph showing the results of a combustion test performed on Example 3 and Comparative Example 2, and the mass of the refractory structural materials measured.

Hereinafter, the present invention will be described in detail based on its preferred embodiments.
A fire-resistant structural material 1A, which is a preferred embodiment of the fire-resistant structural material of the present invention, is shown in FIG. FIG. 1 schematically shows a cross section perpendicular to the axial direction of the fireproof structural material 1A. The fireproof structural material 1A of this embodiment is a structural rectangular material used as a building beam or a pillar. As shown in FIG. 1, the refractory structural material 1A includes a wooden or steel load bearing portion 11a, a refractory coating layer 12a, and a burnt-out coating layer 13a.

The load-bearing portion 11a is designed in cross-section so that the load-bearing portion 11a alone is safe in terms of structural strength against long-term loads (long-term loads) such as fixed loads, load loads, and snow loads. Such cross-sectional designs are known. The cross-sectional shape of the load-bearing portion 11a is rectangular, and the longitudinal length and the lateral length of the load-bearing portion 11a in the cross-section of the refractory structural material 1A correspond to the shape or size of the beam or column. etc. can be changed as appropriate.

The refractory coating layer 12a covers the load bearing portion 11a. In this embodiment, the refractory coating layer 12a covers four axial sides of the load bearing portion 11a. When the refractory structural material 1A is a beam, the refractory coating layer 12a may cover three axial side surfaces of the load supporting portion 11a. The side surface of the refractory structural material 1A on which the refractory coating layer 12a is not formed may be covered with a floor or the like to cover the upper side of the load supporting portion 11a.

The burnable coating layer 13a covers the fireproof coating layer 12a. The burnable coating layer 13a is designed to burn and burn off when exposed to flame. Also, the burn-out coating layer 13a has a thickness of less than 25 mm. Since the thickness of the burnable coating layer 13a is less than 25 mm, the burnable coating layer 13a is reliably burnt off. With such a configuration of the burnable coating layer 13a, the fireproof structural material 1A of the present embodiment can prevent the fireproof coating layer 12a from becoming red hot. Although the reason why the fireproof coating layer 12a can be prevented from becoming red hot in the fireproof structural material 1A of the present embodiment is not completely clear, the present inventors presume as follows.

Combustion of the refractory structural material 1A is considered to proceed in the following order.
When the refractory structural material 1A is exposed to flame, first, a thermal decomposition reaction mainly occurs in the burnable coating layer 13a, and carbonization of the burnable coating layer 13a occurs (first stage). In the first stage, the temperature of the refractory coating layer 12a rises. Then, the thermal decomposition reaction of the burnable coating layer 13a is completed, the oxidation reaction of the burnable coating layer 13a mainly occurs, and the burnable coating layer 13a turns to ash and begins to burn off (second stage). In the second stage, a thermal decomposition reaction mainly occurs in the refractory coating layer 12a, and carbonization of the refractory coating layer 12a occurs. Then, the burnable coating layer 13a is completely burnt out (third stage). In the fourth stage, the refractory coating layer 12a undergoes an oxidation reaction together with a thermal decomposition reaction. Then, the thermal decomposition reaction of the refractory coating layer 12a is completed, and the oxidation reaction of the refractory coating layer 12a mainly occurs (fourth stage). After that, the oxidation reaction of the refractory coating layer 12a is completed, and the refractory structural material 1A stops burning (fifth stage).
As described above, in the refractory structural material 1A of the present embodiment, the thermal decomposition reaction of the refractory coating layer 12a occurs after a while from the start of combustion. Therefore, the surface of the refractory coating layer 12a can be kept smooth for a while after combustion starts. In addition, it is possible to shorten the time during which the thermal decomposition reaction and the oxidation reaction of the fireproof coating layer 12a are taking place, out of the time during which the fireproof structural material 1A is burning. Due to these factors, the fireproof structural material 1A of the present embodiment is less prone to cracks or the like in the fireproof coating layer 12a, and can be prevented from being continuously red-heated.

In addition, even if cracks or the like are generated in the burnable coating layer 13a due to thermal decomposition reaction or oxidation reaction, and red heat is generated in the cracks, the burnable coating layer 13a is burned out. Layer 13a does not remain red hot. Therefore, it is possible to prevent red heat from the burn-out coating layer 13a from being transmitted to the fire-resistant coating layer 12a. This also contributes to suppressing red heat of the fireproof coating layer 12a.

The thickness of the burnable coating layer 13a is preferably less than 25 mm, more preferably less than 20 mm, from the viewpoint of making the burnable coating layer 13a more easily burnt off when the refractory structural material 1A is burned. Here, when the thickness is 25 mm or more, the combustion time until the member burns out becomes long, and the combustion of the member itself continues for a long time, which is not preferable. The thickness of the burn-off coating layer 13a is preferably 10 mm or more, more preferably 15 mm or more, from the viewpoint of delaying the start time of thermal decomposition reaction or oxidation reaction of the fire-resistant coating layer 12a.

The refractory structural material 1A of the present embodiment is the refractory structural material 1A and the comparative structural material in which the burnable coating layer 13a of the refractory structural material 1A is replaced with the refractory coating layer 12a. It is preferable to satisfy the following criteria (1) and (2) when performing a 60-minute combustion test with standard heating.
Criterion (1): The refractory structural material 1A has a higher mass reduction rate than the comparative structural material immediately after the heating is completed.
Criterion (2): Within 180 minutes after the end of heating, the refractory structural material 1A has a lower mass reduction rate than the comparative structural material.
It is considered that the fact that the refractory structural material 1A satisfies the criterion (1) means that the burnable coating layer 13a is more likely to burn off when exposed to flame. Further, the fact that the fire-resistant structural material 1A satisfies the criterion (2) is considered to mean that the thermal decomposition reaction and oxidation reaction of the fire-resistant coating layer 12a settle down at an earlier stage after the burn-out coating layer 13a is destroyed by fire. Therefore, the refractory structural material 1A that satisfies the criteria (1) and (2) can further suppress red heat of the refractory coating layer 12a.

More specifically, the comparative structural material has the same configuration as the refractory structural material 1A except that the fire-resistant coating layer 13a in the refractory structural material 1A is replaced with the refractory coating layer 12a. there is The dimensions of the cross section of the comparative structural material and the dimensions of the cross section of the fireproof structural material 1A are the same. As a structural material for comparison, in place of the burnable coating layer 13a and the fireproof coating layer 12a in the fireproof structural material 1A, the fireproof coating layer 12a having the same thickness as the total thickness of the burnable coating layer 13a and the fireproof coating layer 12a is used. It can also be manufactured by

The mass reduction rate can be measured, for example, as follows.
<Method for measuring mass reduction rate>
First, the refractory structural material 1A and the comparative structural material are subjected to a combustion test for 60 minutes by standard heating in accordance with ISO834-1. At that time, the mass change of the refractory structural material is measured.
Let W be the mass of the structural material at time T minutes after the start of heating, and W _Δ be the mass of the structural material at time T _Δ one minute after time T. Then, the mass reduction rate is calculated by the following formula.
Mass reduction rate (kg/min) = (WW _Δ )/(T _Δ -T)
When calculating the mass reduction rate immediately after the end of heating, T may be set to 60 (minutes).

The thickness of the refractory coating layer 12a is preferably 60 mm or more, more preferably 60 mm or more, from the viewpoint of making it easier for the refractory coating layer 12a to remain when the refractory structural material 1A is burned and improving the fire resistance performance of the refractory structural material 1A. is 75 mm or more. Further, when the load supporting portion 11a is made of steel, the thickness of the fireproof coating layer 12a is preferably 90 mm or less from the viewpoint of improving the effect of stopping the burning of wood by taking advantage of heat absorption due to the influence of heat conductivity and heat capacity. , more preferably 75 mm or less.

Next, constituent materials of the refractory structural material 1A will be described.
The load bearing portion 11a is made of wood or steel, as described above. When the load-bearing portion 11a is made of wood, laminated lumber, sawn lumber, cross-laminated timber (CLT), laminated veneer lumber (LVL), parallel strand lumber (PSL), and the like can be used as the load-bearing portion 11a. When the load-bearing part 11a is made of wood, the load-bearing part 11a is formed by arranging a laminate in which a plurality of laminas are laminated and bonded in a direction perpendicular to the one direction, arranged side by side in the one direction, and having a rectangular cross-sectional shape. It may be
When the load supporting portion 11a is made of steel, square steel pipe, H-shaped steel, square steel, flat steel, channel steel, etc. can be used as the load supporting portion 11a. Moreover, even if it is a shape other than these, the thing which can comprise the fireproof coating layer 12a on the circumference|surroundings can be used as the load support part 11a.

The fire-resistant coating layer 12a and the burn-resistant coating layer 13a are made of a simple wooden material. As used herein, pure wood means wood that does not contain flame retardants, incombustible materials, inorganic materials, or the like.

Solid wood for forming the fireproof coating layer 12a includes laminated lumber, sawn lumber, cross laminated lumber (CLT), laminated veneer lumber (LVL), parallel strand lumber (PSL), plywood, and the like. The CLT or laminated wood may be formed by laminating a plurality of laminae each having a rectangular cross section in the transverse direction such that the vertexes of the rectangles overlap each other. Solid wood species constituting the fire-resistant coating layer 12a include larch, Douglas fir, red pine, spruce, white birch, cypress, hiba, zelkova, red pine, radiata pine, etc. Among these, larch is preferred.

Examples of the solid wood constituting the burnable coating layer 13a include laminated lumber, sawn lumber, cross laminated timber (CLT), laminated veneer lumber (LVL), parallel strand lumber (PSL), plywood, and the like. The CLT or laminated wood may be formed by laminating a plurality of laminae each having a rectangular cross section in the transverse direction such that the vertexes of the rectangles overlap each other. Species of solid wood that constitutes the burnable coating layer 13a include cedar, fir, SPF, balsa, and the like, and among these, cedar is preferred.

Bonding of the load-bearing portion 11a and the refractory coating layer 12a, bonding of the refractory coating layer 12a and the burn-out coating layer 13a, and bonding of the lamina constituting each of the load-bearing portion 11a, the fire-resistant coating layer 12a, and the burn-out coating layer 13a. For bonding, various known adhesives conventionally used in the production of fireproof structural materials can be used. Polyurethane-based adhesives, vinyl acetate-based adhesives, and the like can be mentioned, and among these, resorcinol-phenol-based resin adhesives are preferable from the viewpoint of further suppressing red heat.

Next, the red heat suppression method of the present invention will be described. A preferred embodiment of the red heat suppression method of the present invention is a method of covering a structural member having a load bearing portion 11a and a fireproof coating layer 12a covering the load bearing portion 11a with a burnable coating layer 13a. According to the method for suppressing red heat of the present embodiment, the refractory structural material 1A described above is preferably obtained. According to the method for suppressing red heat of the present embodiment, it is possible to prevent the surface of the fire-resistant coating layer 12a from cracking, and to suppress red-heating of the fire-resistant coating layer 12a.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to such Examples.

(Example 1)
A refractory structural material having the same configuration as the refractory structural material 1A shown in FIG. 1 was manufactured. Specifically, a refractory structural member with a wooden load-bearing portion was manufactured. The refractory structure has cross-sectional dimensions of 360 mm x 360 mm and an axial length of 3500 mm. The cross-sectional dimensions of the load-bearing part are 180 mm x 180 mm, the thickness of the refractory coating is 75 mm and the thickness of the combustible coating is 15 mm.
Laminated wood of Japanese larch (density: 0.50 g/cm ³ , moisture content: 12.3%) was used as the load bearing portion and the fireproof coating layer. Laminated lumber of Japanese cedar (density: 0.40 g/cm ³ , water content: 11.22%) was used as the combustible coating layer. A resorcinol-phenolic resin adhesive was used as the adhesive for manufacturing the refractory structural material.

(Example 2)
A refractory structural material having the same configuration as the refractory structural material 1A shown in FIG. 1 was manufactured. Specifically, a refractory structural member having a square steel pipe as a load bearing portion was manufactured. The refractory structure has cross-sectional dimensions of 385 mm x 385 mm and an axial length of 3300 mm. The square steel pipe, which is the load bearing portion, has a cross-sectional dimension of 200 mm×200 mm and a thickness of 9 mm. The thickness of the refractory coating layer is 75 mm and the thickness of the combustible coating layer is 15 mm. In Example 2, a 2.5 mm thick spacer was placed between the load bearing portion and the refractory coating. Spacers were arranged on each of the four side surfaces along the axial direction of the load supporting portion.
As the square steel pipe, STKR400 specified in JIS G 3466 was used. A plywood made of Japanese cedar was used as the spacer. Laminated wood of Japanese larch (density: 0.49 g/cm ³ , water content: 12.2%) was used as the fireproof coating layer. Laminated lumber of Japanese cedar (density: 0.36 g/cm ³ , moisture content: 10.0%) was used as the combustible coating layer.

(Comparative example 1)
A refractory structural material was manufactured in the same manner as in Example 1, except for the following points. The thickness of the refractory coating layer was 90 mm, and no burn-out coating layer was provided. Larch had a density of 0.53 g/cm ³ ±10% and a moisture content of 8-10%. As the adhesive, a Fehr-resorcinol cocondensation resin (PRF) resin adhesive was used.

(evaluation)
(Combustion test)
The refractory structural materials of Examples 1 and 2 and Comparative Example 1 are placed in a test furnace in an upright state, and each of the four sides is heated for 1 hour by ISO834-1 standard heating assuming a normal fire. After completion of heating, the samples of Example 1 and Comparative Example 1 were left to cool in the furnace for 8 hours, and the samples of Example 2 were left to cool in the furnace for 11 hours. At that time, the temperature change at each position indicated by the black dots in FIGS. 2 to 4 was measured, and the temperature change over time at each position was recorded. 2 to 4 are described as position 1 and position 2 using the numbers shown in FIGS. 2 to 4, respectively. The results of measuring the temperature change at each position are shown in FIGS. 5 to 7, respectively. In addition, the states of the heating surfaces of Examples 1 and 2 and Comparative Example 1 were visually confirmed. The states of the refractory structural materials of Examples 1 and 2 and Comparative Example 1 after the combustion test are shown in FIGS. 8 to 10, respectively.

In Example 1, as shown in FIGS. 5(a) to 5(c), at all positions where temperature changes were measured, after the temperature dropped, the temperature did not rise again until the end of the test.
In addition, in the refractory structural material of Example 1, the burning of the cedar board on the surface continued for a while immediately after the end of heating, but the flaming combustion did not greatly affect the temperature inside the furnace. In addition, it was observed that the temperature inside the furnace decreased as the flame subsided. In addition, the cedar board that did not burn out during heating continued to burn red hot while sticking to the larch surface layer, but as the volume decreased and carbonized, it burned off and turned into ash. It was confirmed that it was falling down. In addition, since the cedar and Japanese larch were secondarily adhered with a resorcinol-based resin adhesive, the cedar did not easily fall off. Red-hot cedar sometimes fell into the hearth, but the fallen cedar did not burn for a long time. After the cedar burned out, the larch charred layer was gradually exposed. In Example 1, the surface layer of the larch carbonized layer is not in a state of deeply carbonized hard charcoal compared to Comparative Example 1, but in a state of relatively shallow carbonization, and the red-hot portion of the surface layer is fine and flaky. It was observed to fall.

In Example 2, as shown in FIGS. 6(a) to 6(d), at all positions where temperature changes were measured, after the temperature dropped, the temperature did not rise again until the end of the test.
Further, in the refractory structural material of Example 2, both the temperature inside the furnace and the internal temperature of the structural material turned to a sufficiently downward trend when 12 hours had passed since the start of the combustion test. In addition, no large cracks or the like occurred in the surface layer of the fireproof structural material of Example 2. In addition, the red heat remained slightly on the surface layer when the structural material was removed from the furnace, but it was not so strong as to reignite, but to the extent that it would burn off after several hours.

In Comparative Example 1, as shown in FIG. 7A, at position 5, the temperature did not decrease from the end of heating to the end of the test, and combustion continued. Also, at positions 3 and 7, the temperature reaches a peak, then drops, and then rises again. From this, at positions 3 and 7, after the fire was once extinguished, red heat remaining in another part was transmitted to positions 3 and 7, and combustion started again. Also, as shown in FIG. 7(b), at positions 12, 13, and 14, the temperature rises after it drops, so the red heat remaining in another part is transmitted, and combustion starts again. It is thought that

In addition, the refractory structural material of Comparative Example 1 had large cracks on the surface after the start of heating. In addition, many of the carbonized layers fell off during heating to the initial stage of cooling. In addition, even after the heating was completed, red-hot combustion continued strongly inside the cracks (unevenness) that had occurred throughout the entire member, and large damage to the refractory coating layer was observed. In Comparative Example 1, the charred layer of Japanese larch remained relatively firm and had deep cracks.
From the results of Examples 1 and 2 and Comparative Example 1, it can be seen that red heat of the refractory structural material can be suppressed according to the present invention.

Further, in Example 2, as shown in FIG. The temperature at position 6, which is located between the corners of (hereinafter referred to as "central part"), also reaches a peak and then begins to fall. On the other hand, in Example 1, as shown in FIG. not following. It is believed that this difference is due to the difference in the load-bearing portions of Examples 1 and 2. FIG. Specifically, in Example 2, since the refractory structural material has a square steel pipe as a load bearing part, the fireproof coating near the corners of the structural material, more specifically, the corners of the square steel pipe. The surface facing the layer (hereinafter referred to as the outer surface of the corner of the square steel pipe) and the surface of the fire-resistant coating layer facing the square steel pipe (hereinafter referred to as the inner surface of the fire-resistant coating layer) are approximately parallel. It is considered that the heat is transmitted to the central portion of the structural member through the square steel pipe, which has high thermal conductivity. The expression that the outer surface of the corner of the square steel pipe and the inner surface of the refractory coating layer are substantially parallel means that the curvature of the outer surface of the corner of the square steel pipe in the direction parallel to the inner surface of the refractory coating layer is approximately 0. . According to Example 2, it is possible to suppress the concentration of heat in the vicinity of the corners of the refractory structural material, and it is thought that red heat can be further suppressed.

(Example 3)
A refractory structural material having the same configuration as the refractory structural material 1A shown in FIG. 1 was manufactured. Specifically, a refractory structural member with a wooden load-bearing portion was manufactured. The refractory structure has cross-sectional dimensions of 330 mm x 330 mm and an axial length of 1600 mm. The cross-sectional dimensions of the load-bearing part are 180 mm×180 mm, the thickness of the refractory coating is 60 mm and the thickness of the combustible coating is 15 mm.
Laminated wood of Japanese larch (density: 0.49 g/cm ³ , moisture content: 9.5%) was used as the load bearing portion and the fireproof coating layer. Laminated lumber of Japanese cedar (density: 0.33 g/cm ³ , water content: 10.9%) was used as the combustible coating layer.

(Comparative example 2)
A refractory structural material was manufactured in the same manner as in Example 3, except for the following points. The thickness of the refractory coating layer was 75 mm, and no burn-out coating layer was provided. Larch had a density of 0.50 g/cm ³ and a moisture content of 9.7%.

(Evaluation of mass reduction rate)
The refractory structural materials of Example 3 and Comparative Example 2 were suspended from the ceiling in the test furnace so that the axial direction of the refractory structural materials coincided with the vertical direction, and a normal fire was assumed for each of the four sides. Heating was performed for 1 hour according to ISO834-1 standard heating, and after the heating was completed, cooling was performed in the furnace for 6 hours. At that time, the mass change of each refractory structural material was measured, and the change over time of the mass of each structural material was recorded. The results are shown in FIG. In addition, since the output of the heating burner is increased in order to raise the temperature in the furnace for 30 minutes from the start of heating, the pressure in the furnace tends to fluctuate, making it difficult to accurately measure the mass. Therefore, FIG. 11 shows the measurement results after 30 minutes when the in-furnace pressure is stable.

As shown in FIG. 11, immediately after the end of heating, that is, 60 minutes after the start of heating, Example 3 has a higher mass reduction rate than Comparative Example 2. Moreover, within 180 minutes after the end of heating, specifically at the time point of 30 minutes after the end of heating, Example 3 has a lower mass reduction rate than Comparative Example 2. Immediately after the end of heating, Example 3 has a larger rate of change in mass reduction rate than Comparative Example 2, but after that, Example 3 has a smaller rate of change in mass reduction rate than Comparative Example 2. It's becoming Further, when comparing the refractory structural material of Example 3 and the refractory structural material of Comparative Example 2 after the combustion test, the refractory structural material of Example 3 had no large cracks or cracks, and no red heat remained. On the other hand, the refractory structural material of Comparative Example 3 had large cracks, cracks, etc., and red heat remained. Therefore, it can be seen that the refractory structural material of Example 3 can suppress red heat.

1A refractory structural material 11a load bearing portion 12a refractory coating layer 13a burn-out coating layer

Claims (5)

a wooden or steel load bearing;
a refractory coating layer made of solid wood covering the load-bearing portion;
A refractory structural material comprising a burnt-out coating layer having a thickness of less than 25 mm and made of solid wood, which covers the refractory coating layer and burns and burns down when exposed to a flame. When the fire-resistant structural material and the comparative structural material in which the fire-resistant coating layer of the fire-resistant structural material is replaced with the fire-resistant coating layer are subjected to a 60-minute combustion test by standard heating in accordance with ISO834-1. to the
Immediately after the end of heating, the refractory structural material has a higher mass reduction rate than the comparative structural material, and within 180 minutes after the end of heating, the refractory structural material is faster than the comparative structural material. 2. The refractory structural material of claim 1, wherein the mass loss rate is reduced. The tree species of the wood constituting the fireproof coating layer is larch,
3. The fire-resistant structural material according to claim 1, wherein the species of wood constituting said burn-resistant coating layer is Japanese cedar. Refractory structural material according to any one of claims 1 to 3, wherein the load bearing portion is a square steel pipe. A solid wood burn-out property in which a structural material having a wooden or steel load-bearing part and a fireproof coating layer covering the load-bearing part and made of solid wood burns and burns down when exposed to fire. By coating with a coating layer,
A red heat suppression method that prevents cracks from occurring on the surface of the refractory coating layer and suppresses red heat of the refractory coating layer,
A method for suppressing red heat, wherein the burn-out coating layer has a thickness of less than 25 mm.

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