JP2022089421A - Preparation method of gypsum composition for woody fire resistive covering - Google Patents

Abstract

To provide a gypsum composition with excellent workability for forming a gypsum layer in several centimeters at an outer periphery of a woody column or beam, and a fire resistive structural material using the gypsum.SOLUTION: A preparation method of a gypsum composition for a woody fire resistive covering, includes making an adjustment so that a hardening start time is equal to or greater than 30 minutes and a density of a gypsum hardening body is equal to or greater than 1.2 g/cm3, where the gypsum composition comprises gypsum, water and a delaying agent and/or a water reducing agent.SELECTED DRAWING: Figure 12

Description

The present invention relates to a fireproof technique for wood-based structural materials.

Wood is a familiar material and has been used for construction of houses and the like since ancient times, and the forest resources that have been planted after the war have been enriched. On the other hand, wood is a flammable material, and it is difficult to use it as a building material because the quality of single wood varies.
Highly uniform wood-based materials have also been developed, such as laminated lumber, and can be used for large-scale buildings. Various measures against flammability are also being considered. For example, there are a method of impregnating with a flame retardant and a method of covering with a flame retardant material or a refractory material.
On the other hand, with the enforcement of the "Act on Promotion of Wood Use in Public Buildings" in 2010, the momentum for wood use in buildings is increasing.

Here are some conventional suggestions for flammability measures.
Patent Document 1 (Japanese Unexamined Patent Publication No. 2012-136939) proposes to improve fire resistance by arranging a flame-retardant-treated material in the outer corner of a load-bearing portion and providing an outer peripheral material such as Douglas-fir. There is.
In Patent Document 2 (Japanese Unexamined Patent Publication No. 2006-218707), the inner layer laminated wood and the outer layer laminated wood are bonded with an epoxy resin, isocyanate resin, or urethane resin adhesive, and a resorcinol resin adhesive is used for the inner layer laminated wood. Wood-based structural materials that have been used have been proposed.
Patent Document 3 (Japanese Unexamined Patent Publication No. 2005-53195) proposes a composite wood structural material in which a noncombustible material such as mortar or metal is arranged on the outside of a load bearing layer.
Patent Document 4 (Japanese Unexamined Patent Publication No. 2012-180700) discloses a technique for providing a plurality of foam layers and a metal film on the outside of a xylem.
In Patent Document 5 (Japanese Unexamined Patent Publication No. 2017-2614), a fluid gypsum is poured from above into the gap between the load support portion and the combustion allowance layer to fill the gap, and the gypsum hardens after filling to form a combustion stop layer. A fire-resistant wood column is disclosed that is formed so that the combustion heat of the fuel allowance layer is effectively absorbed by the combustion stop layer.
According to Patent Document 6 (Japanese Unexamined Patent Publication No. 2018-135643), the applicant has provided a load support portion, a wet refractory coating layer coated around the load support portion, and the outer periphery of the fire resistance coating layer. A wood refractory member with a finished wood layer, rock wool and cement, sprayed rock wool mainly composed of water, or a sprayed ceramic refractory coating mainly composed of white cement, aluminum hydroxide, and calcium carbonate. We propose a wood fireproof member in which a wet fireproof coating material is used and a moisture blocking layer is formed between the load support portion and the fireproof coating layer and between the fireproof coating layer and the finished wood layer.
The applicant also referred to Patent Document 7 (Japanese Unexamined Patent Publication No. 2019-78044) as a wood-based load support portion, a moisture-blocking layer provided on the outer surface of the wood-based load support portion, and an effervescent layer that covers the moisture-blocking layer. We propose a wood fireproof member that includes a fireproof coating layer and a finished wood layer provided outside the foamable fireproof coating layer, and the finished wood layer is fixed to a connecting member arranged in the fireproof coating layer.

Japanese Unexamined Patent Publication No. 2012-136939 Japanese Unexamined Patent Publication No. 2006-218707 Japanese Unexamined Patent Publication No. 2005-053195 Japanese Unexamined Patent Publication No. 2012-180700 Japanese Unexamined Patent Publication No. 2017-2614 Japanese Unexamined Patent Publication No. 2018-135643 Japanese Unexamined Patent Publication No. 2019-78044

The present inventors have researched and developed a wood-based fire-resistant structural material in which a gypsum layer is provided on the outer peripheral surface of a wood-based load-bearing portion as a wood-based fire-resistant structural material. The present invention clarifies a gypsum composition exhibiting fire resistance and a gypsum composition excellent in workability that forms a gypsum layer of several centimeters on the outer circumference of a long column or beam, and a fire resistant structural material using the gypsum. The purpose is to develop.

The main solutions of the present invention are as follows.
1. 1. A gypsum composition containing gypsum, water, a retarder and / or a water reducing material, adjusted so that the curing start time is 30 minutes or more and the density of the cured gypsum is 1.2 g / cm ³ or more. A method for formulating a gypsum composition for a wood-based fireproof coating.
2. 2. Further, the water reducing material is characterized by containing a weight ratio of 3 to 10. The method for formulating a gypsum composition for a wood-based refractory coating as described.
3. 3. It is a fireproof structural member (column, beam) of a building with a fireproof coating layer provided on the outer circumference of the load support part.
A wooden load support that bears the load,
Moisture blocking layer provided on the surface of the load support part,
A lath wire mesh layer provided on the outside of the moisture blocking layer,
A fireproof coating layer provided on the outside of the lath wire mesh layer,
Equipped with
The fireproof coating layer is a gypsum composition containing gypsum, water, a retarding material and / or a water reducing material, and the curing start time is 30 minutes or more, and the density of the cured gypsum body is adjusted to 1.2 g / cm ³ or more. Being formed of a gypsum-based hardened body containing the gypsum composition,
A fireproof structural material characterized by.
4. 3. The fireproof coating layer is 60 mm or more, and the fireproof time is 2 hours or more. The fireproof structural material described.
5.3. Or 4. In the above-mentioned fireproof structural material, a moisture blocking layer and a lath wire mesh layer are formed on the surface of a wooden load support portion, a formwork is provided with a gap of 60 mm or more on the outer periphery thereof, and gypsum, water and a retarding material are provided in the gap. And / or a gypsum composition containing a water reducing material, wherein the gypsum composition having a curing start time of 30 minutes or more and the density of the gypsum cured product adjusted to 1.2 g / cm ³ or more is filled and cured. A method of manufacturing fireproof structural materials for buildings.

1. 1. The present invention adjusts the composition of gypsum containing gypsum, water, and retarder to a hardening start time of 30 minutes or more and the density of the hardened gypsum to 1.2 g / cm ³ or more to achieve fire resistance and good workability. Can be realized.
2. 2. Gypsum composition with a curing start time of 30 minutes or more and a cured body density of 1.2 g / cm ³ or more is based on a weight ratio of gypsum: water: retarding material (: water reducing material) = 100: 30 to 50: 0.01 to 1. 0 (: 3 to 10) is appropriate. The delay material is preferably 0.03 to 0.3% by weight. In particular, the amount of the retarder added is 0.3% by weight, which is sufficient for securing the pot life, and the need for further addition is small.
According to the present invention, the hardened gypsum forming the fire-resistant coating layer is added with a water-reducing material as needed to gypsum, water, and a retarding material, and stirred after preparation to affect the curing start time. Can be adjusted to a predetermined amount in the stirring process. According to the present invention, the target density and the curing start time can be appropriately set.
Structural materials such as columns and beams have a length of 3 m or more, and a thin gypsum layer will be provided, so if preparation time is included, 30 minutes or more will be secured as a handling time before the start of hardening. Is required.
3. 3. It is possible to manufacture a fire-resistant structural material in which a gypsum composition is filled in a formwork having a gap for filling of several centimeters on the outer periphery of the load-bearing portion to form a gypsum layer having a density of 1.2 g / cm ³ or more. .. By constructing pillars and beams as wood-based fireproof structural members, wood can be used as the main load-bearing material. By providing the water blocking layer, the water from the filled gypsum composition containing 30 to 50% of water does not transfer to the wood layer, so that the swelling of the wood layer is prevented and the amount of water that the gypsum is hydrated and hardened. Can be prevented from locally changing to cause hardening of gypsum and variation in material.
4. According to the present invention, gypsum, water, and a retarding material are mixed in a predetermined weight ratio, and after stirring, they are filled and hardened to form a hardened gypsum body to form a fireproof coating layer, thereby forming a required fireproof performance. It is possible to secure a density that satisfies the above, and a threshold of 30 minutes or more for the time when the liquid gypsum starts to harden. Therefore, since the fire-resistant coating layer can be formed of a hardened gypsum, even if the cross section of the wood-based load-bearing portion is rectangular or circular, the wood-based load-bearing portion and the fire-resistant coating layer are in close contact with each other. Fireproof structural members are feasible. The fire-resistant structural material of the present invention can exhibit a fire-resistant performance of 2 hours or more.
5. In the wood-based fireproof structural member of the present invention, a moisture blocking layer and a lath wire mesh layer are provided on the surface of a load-bearing portion, and a gypsum composition is filled on the outside thereof to form a gypsum layer. The moisture blocking layer prevents moisture from migrating to the wood material which is the load supporting portion, and the moisture concentration in the gypsum composition is maintained to form a hardened gypsum layer uniformly. Furthermore, the adhesion of gypsum is secured by the lath wire mesh. This lath wire mesh can also be provided on the surface of the gypsum layer, and the lath wire mesh layer on the surface side can prevent the gypsum layer from drying up and falling off due to heat exposure. Since the present invention is a fire-resistant structural member that does not require a wood layer as a fuel allowance layer as the outermost layer, it is useful to use a lath wire mesh as a measure against radiation exposure that comes into direct contact with adhesion or fire.

Diagram showing an example of fireproof structural material The figure which shows the surface maximum temperature about the diagonal position of the wooden pillar surface The figure which shows the surface maximum temperature about the opposite side position of the wooden pillar surface Diagram showing the thermal conductivity of gypsum Figure showing the specific heat of gypsum The figure which shows the comparison between the result of Experiment 1 and the analysis result with the tuned thermal constant. Figure showing the temperature of the surface of the wooden pillar Figure showing the cross-sectional temperature distribution of wooden pillars at gypsum density (1.4 g / cm ³ ) The figure which shows the example of the fire-resistant structural material The figure which shows the construction example of the fireproof structural material of an Example Fire resistance test Figure showing changes in heating temperature Fire resistance test The figure showing the surface temperature change of the load support part

<Outline of the invention>
The present invention relates to a gypsum-based composition used for producing a wood-based fire-resistant structural material.
In the field of construction, gypsum plate is generally used as a refractory material. Although it was difficult to use wood as a structural material for large buildings from the viewpoint of fire resistance, a method of covering the wood with a non-combustible material such as gypsum or mortar to improve fire resistance has also been proposed.
In order to prevent the structural material from collapsing due to a fire, there is an allowable temperature of the material according to the load. For wooden materials, the temperature is about 260 ° C. The present inventors have proposed a fireproof structural material (see FIG. 1) capable of suppressing the temperature of wood to 260 ° C. or lower by providing a gypsum layer around a wood-based load support portion. Since gypsum begins to thermally decompose at 100 ° C. and releases water of crystallization, this phenomenon is used to suppress the temperature rise of wood.
For wooden columns and beams used in large buildings, square timbers and columns with a thickness of 50 cm or more and a length of about 3 to 10 m are required to satisfy the strength such as load capacity, and a gypsum covering layer is required around them. It is necessary to form 60 mm or more.

Fluid gypsum mixed with water and agitated will harden in a short time and is not suitable for building structural materials that fill narrow and long gaps. It is known that the curing start time becomes longer when a large amount of water is added, but the effect on fire resistance is unknown.
The present invention clarified the density of gypsum that affects fire resistance, and investigated gypsum that can satisfy the workability (usable time required for filling work, etc.) of the gypsum layer formed on the outer periphery of the wood-based load bearing portion. ..
As a result of the examination, it was found that the gypsum density should be 1.2 g / cm ³ or more, and the gypsum hardening start time should be 30 minutes or more.
The present invention proposes a gypsum composition that satisfies this density and curing start time.
The composition of the gypsum is 100: 30 to 50,: 0.01 to 1.0 in terms of weight ratio of gypsum: water: retarder. The delay material is preferably 0.03 to 0.3% by weight. Further, it is desirable to include the water reducing material in the range of the weight ratio of 3 to 10.
This gypsum composition is mixed and stirred, filled in the gaps of the wood-based load-bearing portion covered with a formwork, and cured to produce a fireproof structural material. In order to evenly cover the surface of columns and beams having a length of 3 m or more with a thickness of 60 to 90 mm, it is necessary to ensure long-term fluidity.

For example, assuming a pillar with a length of 500 cm, a square of 60 cm, and a gypsum layer of 65 mm, the filled gypsum fluid is about 900 liters, the gypsum fluid to be prepared is about 1 m ³ , and the filling speed is 30 to fill within 30 minutes. Requires liters / minute. Since it is necessary to evenly cover the entire surface of the pillar with gypsum, preparation time and sufficient working time are required. Further, considering that the gypsum composition adhering to or remaining on the mixing device needs to be cleaned before it hardens and prepared for the next time, the hardening start time after the preparation needs to be longer.

The terms are used as follows.
"Gypsum" is a compound name, and "gypsum" is a cured product. The "gypsum composition" indicates the composition of a hardened gypsum such as "gypsum, water, retarder, and water reducing material". The fluid obtained by stirring the "gypsum composition" is called "gypsum fluid".

<About fireproof structural materials>
The fire-resistant structural material of the present invention is a structural material such as a column or a beam having fire resistance by forming a gypsum layer around a load-bearing portion of a wooden system.
The load-bearing part may be a single tree, but laminated lumber that can have properties such as strength and can be freely designed in size is suitable. As the tree species constituting the laminated lumber, commonly used tree species such as cedar, cypress, pine, rice cypress, and rice pine can be used.
The gypsum layer shall have a layer thickness that clears the building fire resistance standards. At present, as a result of examination, it has been found that in the present invention, it is necessary to provide about 60 to 80 mm in order to clear the fire resistance for 2 hours.
In the present invention, as a fireproof structure, it is not necessary to provide a fuel allowance layer on the outside of the gypsum layer. However, it is the same as general building materials that exterior materials can be provided like reinforced concrete columns.
Further, in the fireproof structural material of the present invention, a water-impervious material, an adhesive material, or the like is provided around the load-bearing portion, and a gypsum layer is formed on the outer periphery thereof to prevent moisture from migrating to the load-bearing portion. , It is possible to improve the adhesion of gypsum to the load support part.

<Composition elements>
1. 1. Gypsum Gypsum is a material widely used in the fields of medicine, construction, civil engineering, etc., and types of gypsum such as semi-hydrated gypsum can be used.
When gypsum is heated, it has an endothermic effect due to the latent heat generated by the decomposition of water of crystallization and the evaporation of water, and the temperature rise is suppressed in the range of about 100 ° C to 120 ° C.

2. 2. As the water, ordinary water such as tap water and industrial water can be used.

3. 3. Delay material Delay material is used to delay the curing of gypsum. Amino acids, citric acid, borax and the like can be used.

4. Water-reducing material Water-reducing material is used to improve the fluidity during gypsum placement. Naphthalene, sulfonic acid and the like can be used.

<Test example>
The curing start time and density were evaluated for gypsum in which gypsum, water, retarding material, water reducing material, and retarding material were blended into the composition shown in Table 1.
The materials used are as follows.
Gypsum: Semi-water gypsum β-type water; Tap water Water reduction material: Naphthalene-based water reduction material Delay material: Amino acid-based delay material

(1) Formulation Examples 1 and 2 are unsuitable for filling work because the curing start time is within 20 minutes even if the water reducing material is added when the ratio of water is 50% by weight.
(2) Even if 0.1% by weight or more of this tested retarder is added, it does not affect the extension of the curing start time.

<About analysis confirmation>
Based on the test results, further analysis was performed on density and curing performance.
Figures 2 and 3 show the maximum temperature at the opposite side of the wooden pillar end and the diagonal position of the wooden pillar end.
From FIG. 2, the density of gypsum having a diagonal temperature of 260 ° C. or less is 1.2 g / cm ³ or more, and from FIG. 3, the density of gypsum having a diagonal temperature of 260 ° C. or less is about 0.9 or more. This analysis also revealed that the gypsum density should be 1.2 g / cm ³ or more.

<About analysis>
1. 1. About the analysis The temperature of the wooden pillar covered with gypsum is predicted by heat conduction analysis, and the effect of the difference in gypsum density on the surface temperature of the wooden pillar is examined. The examination policy is as follows.
(1) The thermal constant of gypsum is measured from a test piece having a gypsum coating of 60 mm in which a heating experiment was carried out. Based on the thermal constant of the experimental test piece having a gypsum coating of 60 mm, the thermal constant of the gypsum thickness of the wooden pillar to be analyzed is estimated at 65 mm.
(2) For the wooden pillar to be analyzed, the gypsum coating thickness is 65 mm, and the relationship between the gypsum density and the wood surface temperature is examined using the gypsum specific gravity (density 1.2 g / cm ³ ) as a calculation variable.
(3) The validity of the analysis was examined by comparing the experimental results (experiment 2) with a stone thickness of 65 mm (density 1.33 g / cm ³ ) and the calculation results (density 1.2 g / cm ³ ) with a stone thickness of 65 mm. do.

2. 2. Thermal conduction analysis method 2.1 Thermal constant used for thermal conduction analysis The thermal constant of gypsum is tuned for a test piece with a wooden pillar size of □ 120 mm and a gypsum thickness of 60 mm.
The thermal constants of the wooden columns used in the calculation were constant, with the thermal conductivity set to 0.107 W / mK, the specific heat set to 1.356 kJ / kgK, and the density set to 0.37 g / cm ³ . The moisture content of wood was set to 10%.
The thermal conductivity of gypsum used in the calculation is shown in FIG. 4, and the specific heat is shown in FIG. The density was 1.22 g / cm ³ measured from the test piece.

2.2 Tuning of latent heat of vaporization for test results When gypsum is heated, the endothermic effect is exerted by the latent heat of decomposition of water of crystallization and evaporation of water, and the temperature rise is suppressed in the range of about 100 ° C to 120 ° C.
Therefore, the latent heat of vaporization was expressed by the latent heat of vaporization of water, and a parametric study was conducted with the latent heat of vaporization as a variable, and it was examined so that the surface temperature of the wooden pillar in Experiment 1 would be almost the same.
FIG. 6 shows the results when the assumed latent heat of vaporization of gypsum is 20% by mass ratio. Subsequent analyzes will be carried out using these thermal constants tuned from the experimental results.

3. 3. Effect of gypsum density on gypsum temperature The heat conduction analysis is performed using the gypsum density as a calculation variable, using the above thermal constants (other than gypsum density) with the gypsum thickness (□ 120 mm) and gypsum thickness set to 65 mm. implement. Since the analysis of the heat history is based on the thickness of the stone, it is not related to the size of the wooden pillar, so a 120 mm square pillar material was used as the test piece.
The time history of the wooden pillar surface temperature is shown in FIG. 7, and the relationship between the gypsum density and the maximum temperature of the wooden pillar surface is shown in FIGS. 2 and 3. As an example of the heat conduction analysis result, FIG. 8 shows a cross-sectional temperature distribution in which the density of gypsum is 1.4 g / cm ³ .
As shown in FIG. 7, it can be seen that the maximum temperature of the surface of the wooden pillar decreases as the density of gypsum increases. This is mainly due to the following reasons.
-In the heat conduction of an individual, the smaller the thermal diffusivity (= λ / (ρc)) obtained by dividing the thermal conductivity λ by the specific heat c and the density ρ, the more difficult it is to transfer heat. Therefore, the higher the density of gypsum, the lower the wood surface temperature.
・ Gypsum requires a large amount of heat to decompose water of crystallization. The higher the density of gypsum, the larger the amount of heat required for this latent heat. Therefore, the higher the density of gypsum, the lower the wood surface temperature.

According to FIG. 8 showing the temperature distribution of the test piece, even if the surface temperature reaches 800 ° C. or 1000 ° C., the wood surface of the load-bearing part is 260 ° C. or less, and the load-bearing part is damaged or deteriorated. It can be seen that it does not occur, maintains sufficient strength, and has fire resistance.

4. Comparison of calculation results and experimental results In Experiment 2, a loading heating experiment with a wooden pillar □ 120 mm and a gypsum thickness of 65 mm was carried out. A comparison of the experimental results and the analysis results is shown in FIGS.
The analysis results are generally in agreement with the experimental results.

FIG. 9 shows an example of a cross section of a fireproof structural material which is a pillar material. (A) is an exploded view, and (b) is a cross section.
A load support portion 2 made of a laminated material of cedar that bears a load, a moisture blocking layer 3 and a lath wire mesh 5 provided on the outer peripheral surface of the load support portion 2, and a gypsum layer 4 provided on the outside of the lath wire mesh 5. , A connecting material that penetrates the gypsum layer 4 and joins the second lath wire mesh 6 provided on the surface side of the gypsum layer 4 to the surface of the load support portion 2 and the other end to the second lath wire mesh 6. It is composed of 7 and surface coating 8.
Since the upper and lower ends of the pillar material, which is a fireproof structural material, are inserted into the slab or the beam, no gypsum layer is provided.
A heating test was conducted using the fire-resistant structural material 1 having a thermocouple attached to the load-bearing portion to confirm the fire-resistant performance.

The connecting material 7 does not need to be directly bonded to the surface of the load supporting portion 2, and may be provided via the moisture blocking layer 3 if the bonding strength capable of supporting the lath wire mesh 6 on the surface side can be obtained. can.
Further, the lath wire mesh 6 corresponds to the adhesive layer, and the second lath wire mesh corresponds to the second adhesive layer. Dried gypsum is used for the connecting material 7, and the moisture blocking layer 3 is formed of xyladecol conzorane.

The specifications of the pillar material of this embodiment are as follows.
Overall length: 3300 mm, length and width: 250 mm square,
Load-bearing part; 120 mm square (In this embodiment, since it is for confirming fire resistance, the size of the load-bearing part is assumed to be 120 mm square).
Fire-resistant coating layer: Gypsum layer thickness 65 mm (100 parts by weight of gypsum, 45 parts by weight of water, 3 parts by weight of water-reducing material, 0.1 parts by weight of delay material), gypsum density 1.33 g / cm ³
Connecting material: 50 mm square, 65 mm long,
Moisture blocking layer: Xyladecol Conzolan (coating amount 250 g / m ² ),
Adhesive layer (second adherent layer): Lath wire mesh,
Surface coating: Xyla decor interior fine top coat (application amount 500g / m ² )

FIG. 10 shows the manufacturing process of this embodiment.
First step: The load support portion 2 is prepared, and 250 g / m ² of xyladecol conzorane is applied to the outer peripheral surface to form the moisture blocking layer 3.
A groove is cut in a part of the load support portion for the test, a thermocouple is installed, and then a moisture blocking layer is formed.
Second step: A lath net is attached to the surface of the load support portion 2 with a stapler to form an adhesive layer.
Third step: The connecting material 7 is attached to the surface of the load supporting portion 2 with an adhesive. In this case, the lath wire mesh is partially cut off and the connecting material is adhered to the load supporting portion.
Fourth step: A second lath wire mesh 6 is installed at the outer end of the connecting member 7, and a formwork 9 is installed on the outer periphery thereof. The second lath wire mesh is temporarily bonded to the inner surface of the mold 9 by cutting off the connecting material portion. The connecting material 7 also functions as a spacer for the formwork.
Fifth step: Gypsum is filled and hardened to form a refractory coating layer 4, and the formwork 9 is demolded.
Sixth step: A coating amount of 500 g / m ² is applied to the surface after demolding to form a surface coating 8 to form a finishing layer.

<Fire resistance test>
A fire resistance test was conducted using the pillar material prepared in this example as a test body. The fire resistance test was conducted in accordance with the provisions of the fire resistance performance test / evaluation work method manual of the Building Materials Testing Center (General Foundation).
FIG. 11 shows a change in the heating temperature of the heating furnace.
The heating was carried out so as to reach 1000 ° C. or higher within 120 minutes, and then heat was dissipated until 480 minutes. The heating temperature is indicated by a solid line, and the temperature during heat dissipation is indicated by a dotted line.
The temperature of the test piece was measured at the corners and the center of the wood, which is the load bearing. Although the measurements were made at a plurality of locations, the same results were obtained, so the temperature change at each location is shown in FIG.

After 30 minutes, the heating temperature is 800 ° C. or higher, but the temperature of the corners of the test piece is 100 ° C., and the heating temperature reaches 1100 ° C. or higher over 120 minutes, but the temperature of the test piece is 100 ° C. Maintaining. After that, the temperature of the corner of the test piece reached about 200 ° C. in 300 minutes, and then gradually decreased to 150 ° C.
The temperature of the central part of the test piece was maintained at 100 ° C. after 30 minutes and 100 ° C. even at 120 minutes, then increased to about 175 ° C. in 330 minutes, and then gradually decreased to 150 ° C. ..
In particular, when the temperature of the test piece reaches 100 ° C in 30 minutes of heating, the temperature is 100 ° C for a while and the temperature is maintained for 120 minutes or more after heating, which means that the heat insulation of the stone and the water of crystallization contained in the stone evaporate. It was confirmed that the heat of vaporization prevented the surface temperature of the test piece from rising.
Shallow cracks were observed on the surface of the test piece after heating, but gypsum was not peeled off, and no cracks reaching the load bearing part were observed on the cut surface. Even when observing the cut surface, the load bearing part was not carbonized.
As a result, it was confirmed that this test piece sufficiently satisfied the fire resistance for 2 hours.
As a result of conducting the same fire resistance test on the test piece with a gypsum layer of 70 mm, the maintenance time of the test piece at 100 ° C was extended, and the maximum temperature of the test piece was suppressed to 175 ° C or less in both the corners and the central part. It has been confirmed that it will be done.

1 ... Fireproof structural material 2 ... Load support 3 ... Moisture blocking layer 4 ... Gypsum layer 41 ... Wet fireproof coating material

5 ... Adhesive layer 6 ... Second adhesive layer (second wire mesh layer)
7 ... Connecting material (spacer)
71 ・ ・ ・ ・ ・ Dry fireproof coating material 8 ・ ・ ・ ・ ・ ・ Surface coating 9 ・ ・ ・ ・ ・ ・ Formwork

Claims (5)

A gypsum composition containing gypsum, water, a retarder and / or a water reducing material, adjusted so that the curing start time is 30 minutes or more and the density of the cured gypsum is 1.2 g / cm ³ or more. A method for formulating a gypsum composition for a wood-based fireproof coating. The method for formulating a gypsum composition for a wood-based refractory coating according to claim 1, further comprising a water-reducing material having a weight ratio of 3 to 10. It is a fireproof structural member (column, beam) of a building with a fireproof coating layer provided on the outer circumference of the load support part.
A wooden load support that bears the load,
Moisture blocking layer provided on the surface of the load support part,
A lath wire mesh layer provided on the outside of the moisture blocking layer,
A fireproof coating layer provided on the outside of the lath wire mesh layer,
Equipped with
The fireproof coating layer is a gypsum composition containing gypsum, water, a retarding material and / or a water reducing material, and the curing start time is 30 minutes or more, and the density of the cured gypsum body is adjusted to 1.2 g / cm ³ or more. Being formed of a gypsum-based hardened body containing the gypsum composition,
A fireproof structural material characterized by. The fireproof structural material according to claim 3, wherein the fireproof coating layer is 60 mm or more and the fireproof time is 2 hours or more. In the fireproof structural material according to claim 3 or 4, a moisture blocking layer and a gypsum wire mesh layer are formed on the surface of a wooden load support portion 2, and a formwork is provided on the outer periphery thereof with a gap of 60 mm or more. A gypsum composition containing gypsum, water, a retarding material and / or a water reducing material in the gap, and the hardening start time is 30 minutes or more, and the density of the hardened gypsum is adjusted to 1.2 g / cm ³ or more. A method of filling a composition and curing it to produce a fireproof structural material for a building.

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