WO2005030670A1

WO2005030670A1 - Incombustible composition for access floor board, method of producing access floor board using incombustible composition, and incombustible access floor board using incombustible composition

Info

Publication number: WO2005030670A1
Application number: PCT/KR2004/002448
Authority: WO
Inventors: Jun-Han Choi; Sang-Hoon Lee; Byung-Ick Yoon
Original assignee: Jun-Han Choi; Sang-Hoon Lee; Byung-Ick Yoon
Priority date: 2003-09-29
Filing date: 2004-09-23
Publication date: 2005-04-07
Also published as: KR100535719B1; KR20050031198A

Abstract

Disclosed is an incombustible composition for an access floor board, a method of producing the access floor board using the incombustible composition, and the incombustible access floor board using the incombustible composition. The incombustible composition includes 1 to 90 wt% of stone powder, 1 to 30 wt% of curing fire-retardant resin, 1 to 80 wt% of organic or inorganic fiber, and 1 to 80 wt% of fly ash or bottom ash. Therefore, the incombustible composition is advantageous in that it is environmentally-friendly because it contains waste materials, and that it has excellent hardness, strength, and water resistance. Other advantages are that its production costs are relatively low, and that it has excellent incombustibility, depending on contents of the components constituting the incombustible composition.

Description

Description INCOMBUSTIBLE COMPOSITION FOR ACCESS FLOOR BOARD, METHOD OF PRODUCING ACCESS FLOOR BOARD USING INCOMBUSTIBLE COMPOSITION, AND INCOMBUSTIBLE ACCESS FLOOR BOARD USING INCOMBUSTIBLE COMPOSITION Technical Field [1] The present invention pertains to an incombustible composition for an access floor board, a method of producing the access floor board using the incombustible composition, and the incombustible access floor board using the incombustible composition. More particularly, the present invention relates to an incombustible composition for an access floor board, which is used as a floor finishing system, used to cover wires in office buildings, computer rooms, clean rooms, and the like, being safe from fire, to prevent fire from spreading and to prevent toxic gases from being generated from the floor finishing system when the floor finishing system is on fire, a method of producing the access floor board using the incombustible composition, and the incombustible access floor board using the incombustible composition. Background Art [2] A so-called access floor is a floor finishing system used to cover wires in office buildings, computer rooms, clean rooms, and the like. The access floor, widely used in domestic and overseas construction fields, is mostly consists of a particle board or a steel plate. [3] Even though the particle board, mostly consisting of wood chips, is relatively inexpensive, it has disadvantages in that strength is poor, the generation of fire and toxic gases from the particle board is serious when the particle board is on fire, and durability is reduced when it is exposed to moisture. [4] Meanwhile, the use of the steel plate in producing the access floor prevents the fire from spreading and prevents toxic gases from being generated from the access floor when the access floor is on fire. However, the access floor made of the steel plate has poor heat-intercepting property and processability. Additionally, noises occur when persons walk on the access floor made of the steel plate. Further, it is impossible to enable the access floor to be subjected to various finishing processes, and thus, the access floor made of the steel plate has a limited appearance. As well known to those skilled in the art, desired physical properties required for construction finishing and interior materials may be obtained by changing contents of components constituting the construction finishing and interior materials. However, the access floor made of the steel plate insufficiently has the desired physical properties, and thus, the use of the steel door is applied to limited fields.

[5] A wood-wool cement board may be used as an access floor board. In this regard, the wood-wool cement board is produced by mixing various substances with cement. Examples of the above substances may include relatively light paper particles, perlites, Styrofoam particles, vermiculites, bottom ash, and a mixture thereof, and various additives may be added into the wool-wood cement board in accordance with the use of the wood-wool cement board.

[6] However, the cement constituting the wood-wool cement board may be deformed with time, and an appearance of the wood-wool cement board is relatively rough, preventing the wood-wool cement board from being applied to the access floor. Accordingly, the wood-wool cement board is used as construction exterior or ceiling materials rather than the construction finishing and interior materials.

[7] According to the existing Building Standards Act and Rre Services Act in Korea, a finishing and interior material, used in buildings, must be incombustible, quasi- incombustible, or fire-retardant, and the buildings, larger than a predetermined scale, must include fire-proofing sections to prevent the fire from spreading and to shield persons from fire. As well a fire door, made of a material capable of enduring against fire for 30 minutes or one hour, must be installed at the fire-proofing sections.

[8] Furthermore, the legally regulated finishing and interior material is evaluated as three categories according to a KS (Korean Standards) F2271 method (a fire-retardant performance test method for construction materials): first-grade fire-retardancy (incombustible materials), second-grade fire-retardnacy (quasi-incombustible materials), and third-grade fire-retardancy (fire-retardant materials).

[9] The Building Standards Acts of different countries may be slightly different from each other. However, all countries regulate the standards regarding the performances of the construction finishing and interior material, and the Building Standards Act of each country provides that only the materials, having the performances satisfying the above standards, may be applied to the buildings. The reason for this is that the use of the desirable construction finishing and interior material contributes to preventing the fire from spreading and to shielding persons in the buildings from toxic gases occurring due to fire. Disclosure of Invention Technical Problem

[10] However, most of the commercial construction finishing and interior materials insufficiently satisfy the above standards, and does not sufficiently have other physical properties required to be used as the construction finishing and interior material even though they have incombustibility, quasi-incombustibility, or fire-retardancy.

[11] Heretofore, the construction finishing and interior materials with excellent performances are not yet developed even though many studies have been conducted to develop the construction finishing and interior materials, having incombustibility, quasi-incombustibility, or fire-retardancy. In detail the particle board as described above has poor water-resistance, and no incombustibility, quasi-incombustibility, or fire-retardancy, thereby catching fire easily and accelerating the spread of the fire. Accordingly, the use of the particle board is limited by the existing Building Standards Act in Korea. However, the particle board is the most widely used as the construction interior material because it is relatively inexpensive and lightweight, has excellent pro- cessability, and ease of its use in building constructing is ensured.

[12] As for the wood-wool cement board, it has excellent strength, water-resistance, and incombustibility, quasi-incombustibility, or fire-retardancy. However, the wood-wool cement board has poor processability, and is relatively heavy and easily damaged. As well ease of its use in building constructing is not ensured. Therefore, the wood-wool cement board is used as exterior wall materials or surface materials of the buildings, but scarcely used as the construction finishing and interior materials.

[13] Therefore, the present invention has been made keeping in mind the above problems, such as poor heat- intercepting property of a conventional construction floor material and a difficulty in applying various finishing materials to the conventional construction floor material, occurring in the prior art. Technical Solution

[14] Accordingly, an object of the present invention is to provide an incombustible composition for an access floor board, which mostly consists of waste materials, and which is environmentally-friendly and inexpensive. In this regard, the incombustible composition has excellent hardness, strength, water-resistance, and incombustibility, and also has various appearances.

[15] Another object of the present invention is to provide a method of producing an access floor board using an incombustible composition, having all desirable physical properties, required for construction material, as well as incombustibility. [16] A further object of the present invention is to overcome disadvantages of a conventional steel access floor board, such as poor heat-intercepting property and pro- cessability, the occurrence of noises when persons walk on the conventional steel access floor, and a limited appearance. Furthermore, the present invention provides an incombustible access floor board made of an incombustible composition, which is safe from fire, and which prevents fire from spreading and prevents toxic gases from being generated from the access floor board when the access floor board is on fire. In this respect, the access floor board has various appearances.

[17] In order to accomplish the above object, the present invention provides an incombustible composition for an access floor board, which includes 1 to 90 wt% of stone powder, 1 to 30 wt% of curing fire-retardant resin, 1 to 80 wt% of organic or inorganic fiber, and 1 to 80 wt% of fly ash or bottom ash.

[18] Additionally, the present invention provides a method of producing an access floor board, including providing the incombustible composition; mixing a curing fire- retardant resin and a fly ash or bottom ash with each other; adding an organic or inorganic fiber into a mixture, shattering the mixture containing the organic or inorganic fiber, and mixing stone powder with the shattered mixture by use of a mixer using air; pressing the resulting mixture using a high pressure hot press to form a board; and finishing sides of the board.

[19] Furthermore, the present invention provides an incombustible access floor board produced according to the above method. Advantageous Effects

[20] According to the present invention, there is provided an inorganic access floor board made of an incombustible composition, which is safe from fire, and which prevents fire from spreading and prevents toxic gases from being generated from the access floor board when the access floor board is on fire. In this regard, the access floor board has excellent strength and various appearances (particularly, an imitation- stone appearance), and is competitive in terms of economic efficiency. Additionally, the access floor board prevents noises from occurring when persons walk thereon. Description of Drawings

[21] Best Mode

[22] An incombustible composition for an access floor board according to the present invention includes 1 to 90 wt% of stone powder (a), 1 to 30 wt% of curing fire- retardant resin (b), 1 to 80 wt% of organic or inorganic fiber (c), and 1 to 80 wt% of fly ash or bottom ash (d). In addition, the incombustible composition of the present invention may further include a fire-proofing agent (e).

[23] In the present invention, the stone powder (a) of the incombustible composition for the access floor board has excellent strength, and serves to properly control an amount of the curing fire-retardant resin (b) because the stone powder (a) does not absorb water. Further, it is relatively inexpensive, and thus, it ensures economic efficiency. However, the stone powder (a) has disadvantages of a relatively high weight and poor tensile strength. Accordingly, the stone powder (a) may further contain a fibrous material and a light filler to avoid the disadvantages.

[24] With respect to this, it is preferable that a content of the stone powder (a) in the incombustible composition is 1 to 90 wt% When the content of the stone powder (a) is less than 1 wt%, the stone powder (a) does not act as aggregates affecting combination strength of the incombustible composition. On the other hand, when the content of the stone powder (a) is more than 90 wt%, the stone powder (a) has a rough surface, and reduced tensile strength and elasticity.

[25] The curing fire-retardant resin (b) is added into the incombustible composition such that the incombustible composition has desirable compression and tensile strengths required for construction material as well as incombustibility, is not readily deformed when the incombustible composition is cured, and various finishing materials can be easily attached to the incombustible composition. Examples of the curing fire-retardant resin (b) include a phenol resin, a fire-retardant unsaturated polyester resin, or a melamine resin.

[26] In this respect, it is preferable that the content of the curing fire-retardant resin (b) in the incombustible composition is 1 to 30 wt% When the content of the curing fire- retardant resin (b) is less than 1 wt%, the curing fire-retardant resin (b) insufficiently affects the incombustible composition. On the other hand, when the content of the curing fire-retardant resin (b) is more than 30 wt%, the production costs of the incombustible composition are undesirably increased while an effect of the curing fire- retardant resin (b) to the incombustible composition is no longer increased.

[27] The organic or inorganic fiber (c) is added into the incombustible composition to enable an incombustible construction product, produced using the incombustible composition, to have similar physical properties to MDF or plywood. Accordingly, the organic or inorganic fiber (c) improves compression or tensile strength of the incombustible construction product, so that the incombustible construction product is not easily damaged by relatively high pressure (500kg/20cnf ) and an impact, and has constant elasticity. Further, the organic or inorganic fiber (c) contributes to producing the incombustible construction product in various sizes.

[28] At this time, it is preferable that the incombustible composition contains 1 to 80 wt% of organic or inorganic fiber (c). Examples of the organic fiber include paper fragments shattered into fibroid materials, shattered wood fragments, waste fibers, rice bran, vegetable fibers, and a mixture thereof, and the inorganic fiber is exemplified by rock wool glass wool, basaltic wool, ceramic wool, and a mixture thereof. In this regard, the above exemplified organic or inorganic fibers contain some waste materials.

[29] When the content of the organic or inorganic fiber (c) in the incombustible composition is less than 1 wt%, the incombustible construction product has improved fire-retardancy, but reduced processability or compression/tensile strength due to the relatively high hardness thereof. On the other hand, when the content of the organic or inorganic fiber (c) is more than 80 wt%, the strength of the incombustible construction product is reduced, and thus, the incombustible composition cannot be applied to the access floor board.

[30] Additionally, the fly ash or bottom ash (d) is used to secure sufficient surface strength and a smooth surface of the incombustible construction product. At this time, the density, and surface and compression strengths of the incombustible construction product may be controlled in accordance with the content of fly ash or bottom ash (d) in the incombustible composition. In the present specification, the term "fly ash" means a relatively lightweight ash portion of remaining ash after the burning of coals used as a fuel in a steam power plant, the term "bottom ash" meaning ash portion heavier than fly ash.

[31] Even though the fly ash or bottom ash (d) has lighter specific gravity than the cement, the fly ash or bottom ash (d) has relatively high specific gravity in comparison with other components constituting of the incombustible construction product. Hence, when a fly ash or bottom ash (d) content of the incombustible construction product is relatively high, it is difficult to accomplish the lightening of the incombustible construction product, but it is possible to obtain the strong incombustible construction product having the improved strength.

[32] Therefore, it is preferable that the content of the fly ash or bottom ash (d) in the incombustible composition is 1 to 80 wt% When the content of the fly ash or bottom ash (d) is less than 1 wt%, it is difficult to produce the smooth incombustible construction product having desired surface effect. On the other hand, when the content of the fly ash or bottom ash (d) is more than 80 wt%, the incombustible construction product is relatively high in terms of specific gravity and easily damaged by a relatively weak impact.

[33] Furthermore, even though the curing fire-retardant resin (b) has fire-retardancy, the fire-proofing agent (e) may be added into the incombustible composition so as to minimize the combustion of the incombustible construction product and the occurrence of toxic gases when the incombustible construction product are on fire, thereby the incombustible construction product ensures the better incombustibility or quasi- incombustibility. In this respect, examples of the fire-proofing agent (e) include calci n carbonate, sodi n bicarbonate, sodium carbonate, other carbonates, or a mixture thereof. Further, when the incombustible construction product, containing the fire-proofing agent (e), are on fire at a temperature of 500°C or higher, the fire- proofing agent (e) is decomposed to allow carbon dioxide (CO2) to flow out of the incombustible construction product, thereby extinguishing the fire. Accordingly, the incombustible construction product, containing the four components is improved in terms of the fire-retardancy because of the fire-proofing agent (e). In other words, the quasi-incombustible construction product is improved to the incombustible construction product, and the fire-retardant construction product is improved to the quasi- incombustible or incombustible construction product.

[34] At this time, it is preferable that a content of the fire-proofing agent (e) in the incombustible composition is 1 to 80 wt% When the content of the fire-proofing agent (e) in the incombustible composition is less than 1 wt%, the fire-proofing agent (e) insufficiently affect the incombustible composition. On the other hand, when the content of the fire -proofing agent (e) is more than 80 wt%, the strength of the incombustible construction product is reduced.

[35] Meanwhile, a method of producing the access floor board using the incombustible composition, includes providing the incombustible composition; mixing the curing fire-retardant resin and fly ash or bottom ash with each other; adding the organic or inorganic fiber into a mixture, and mixing the stone powder with the mixture, containing the organic or inorganic fiber, by use of a mixer using air; pressing the resulting mixture using a high pressure hot press to form the board; and finishing the board.

[36] The method may be divided into a mixing process and a pressing process. There will be concretely described the production of the access floor board, below.

[37] <Production of the access floor board according to a compression shaping process> [38] In the method of producing the access floor board according to the present invention, the compression shaping process includes a first mixing process and a second pressing process. In the first mixing process, the curing fire-retardant resin (b), the fly ash or bottom ash (d), and the like are mixed with each other in a form of powder using a mixer after they are weighed with the use of a measuring system. At this time, the fire-proofing agent (e) may be selectively added into a mixture.

[39] Subsequently, the organic or inorganic fiber (c) is added into the mixture. The above components are mixed with each other using the mixer, for instance, a super mixer (Hensel) in which sharp blades revolves in a relatively high speed to uniformly shatter and mix the components, and the stone powder (a) is then added into the mixture. At this time, it is preferable that the mixing is conducted using air for a relatively short time to prevent the properly shattered organic or inorganic fiber (c) from being agglomerated. The resulting mixture is stored in a storage tank until the second pressing process starts.

[40] Meanwhile, it is necessary to properly control contents of the components of the resulting mixture so as to enable the construction product to have a desired specific gravity because the specific gravity of the incombustible construction product is changed according to the use of the incombustible construction product.

[41] For example, when the construction product, such as the access floor board, has the density of 1.0 to 1.3 g/cn , it is needed to increase the content of the component (a) in the incombustible composition so as to improve the specific gravity and strength of the access floor board. However, because it is most preferable that a typical construction interior board has the density of 0.7 to 0.9 g/cn , the contents of the components constituting the incombustible composition may be properly controlled in such a way that the content of the component (c) is increased and the content of the component (a) is reduced.

[42] Subsequently, the components, mixed so as to enable the construction product to have the desired specific gravity, are pressed using a high pressure hot press (500 to 3,000 tons) at 60 to 200°C for 1 to 60 min to accomplish the incombustible access floor board.

[43] If a high pressure hot press with a high frequency heating function is used to press the incombustible composition, the component (b) is quickly cured to significantly reduce a pressing time of the incombustible composition.

[44] Incidentally, the components, fed into the press, may be pressed while reinforcement meshes, made of a glass fiber, are spread on upper and lower sides of the press, or a stainless steel, steel, or aliminim plate may be attached to a backside of the access floor board after the access floor board is accomplished so as to increase compression and tensile strengths of the access floor board.

[45] The construction product according to the present invention, having excellent incombustibility or fire-retardancy, and excellent physical properties, may be usefully applied to the following various fields.

[46] ® Access floor

[47] The access floor, produced using an incombustible board according to the present invention, has excellent fire-resisting and fire-proofing abilities, water resistance, durability, and processability. Additionally, the access floor may have various appearances. The above advantages of the access floor cannot be accomplished by a conventional particle board or a steel plate. Particularly, the access floor may be subjected to a finishing process using an imitation stone or a native stone unlike conventional access floors.

[48] Further, a far-infrared function may be provided to the access floor by adding proper inorganics into the incombustible composition, thereby preventing a fire from spreading, shielding persons from toxic gases generated by fire when the access floor is on fire, and providing helpful functions to residential environment.

[49] © Reinforcing material of an imitation stone or native stone

[50] The relatively thinly processed imitation or native stone may be attached to the incombustible board, produced using the incombustible composition according to the present invention, to reduce the production costs and a weight of the access floor board without changing a surface finishing effect of the access floor board.

[51] Having generally described this invention, a further understanding can be obtained by reference to examples and comparative examples which are provided herein for the purposes of illustration only and are not intended to be limiting unless otherwise specified.

[52] Physical properties of samples according to the examples and comparative examples are evaluated as follows.

[53] 1) Incombustibility, quasi-incombustibility, and fire-retardancy: the samples are evaluated as three categories according to a KS F2271 method (a fire-retardant performance test method for construction materials): first-grade fire-retardancy (incombustible materials), second-grade fire-retardnacy (quasi-incombustible materials), and third-grade fire-retardancy (fire-retardant materials)

[54] 2) Specific gravity and density: The specific gravities and densities of the samples are measured according to a KS L5316 method (test method of physical properties of plaster boards)

[55] 3) Fire resistance: The fire resistances of the samples are evaluated according to a KS F3507 method (plaster boards)

[56] 4) Submergence stability: The submergence stabilities of the samples are evaluated according to the KS F3507 method (plaster boards)

[57] The construction products according to the compression shaping process, as described in the examples, were compared with commercial construction products as described in the comparative examples for the incombustibility, quasi-incombustibility, or fire-retardancy. In this respect, the incombustibility, quasi- incombustibility, or fire-retardancy is considered as the most important factor, to be accomplished in the present invention. In detail, the construction products were evaluated in three categories according to the KS F2271 method: first-grade fire- retardancy (incombustible materials), second-grade fire-retardnacy (quasi-incombustible materials), or third-grade fire-retardancy (fire-retardant materials). In this regards, these evaluations were conducted according to contents of components constituting the construction products and a kind of the construction products, and compared with each other.

[58] Furthermore, a weight per unit area of each construction product was measured, and a weight change of the construction product according to a mixing ratio of the components was measured. Additionally, the stability of each construction product against fire was evaluated by use of fire resistance of the construction product.

[59] Particularly, the submergence stabilities of the construction products were evaluated because it is required that most of the construction finishing and interior materials have the submergence stabilities.

[60] EXAMPLES 1 TO 4

[61] A curing fire-retardant resin (b), a fly ash or bottom ash (d), and a fire-proofing agent (e) were mixed with each other in a mixing ratio as described in the following Table 1 using a mixer after they were weighed with the use of a measuring system. Subsequently, an organic or inorganic fiber (c) was added into a mixture, and uniformly mixed with the mixture while the resulting mixture was shattered using a super mixer (Hensel). Stone powder (a) was then added into the resulting mixture. At this time, the mixing was conducted using air for ten minutes to prevent the properly shattered component (c) from being agglomerated. The resulting composition was stor ed in a storage tank before a second pressing process was conducted. [62] The resulting composition was then pressed using a high pressure hot press (about 1,000 tons) at about 150°C for about 30 min to produce incombustible boards. Physical properties of the incombustible boards were evaluated according to the above evaluation methods, and the results are described in the following Table 1.

[63] TABLE 1 Physical properties of incombustible construction products produced according to a compression shaping process

(a) component (a), stone powder, y^b) component (b), phenol resm, ³(c) component (c), rock wool, (d) component (d), fly ash, ⁵(e) component (e), calcium carbonate, ^hap shape of Ihe construction product, Fire fire-retardancy, ⁸Sp density/specific gravity ⁹Subm. submergence stability

[64] Meanwhile, physical properties of a cαnnercial particle board and wood-wool cement board, widely used as a flooring material, were evaluated according to the above evaluation methods, and the results are described in the following Table 2.

[65] TABLE 2 Physical properties of commercial construction finishing and interior products

(a) component (a), ²(b) component (b), ³(c) component (c), ''Fire fire-retardancy, Sp density/specific gravity ύubm. submergence stability ⁷Fιreres fire resistance

[66] As described in the Table 1, in the example 1, the fire-retardancy and a weight per unit area of the incombustible board, produced according to a dry compression shaping process, are respectively first-grade fire-retardancy and 1.3. In this regard, the weight per unit area of the incombustible board of the example 1 is heavier than that of the combustible particle board, having no fire-retardancy, according to the comparative example 1 as described in the Table 2. Additionally, a combination force between components constituting the incombustible board of the example 1 and elasticity of the incombustible board of the example 1 are poor, and thus, compression strength of the board of the example 1 does not reach 500 kg/20cnf . However, the submergence stability of the incombustible board of the example 1 is excellent, thereby a shape of the board is stably maintained in water without being deformed.

[67] As well, the boards of the examples 2 to 4 as described in the Table 1 each have the first-grade fire-retardancy, like the wood-wool cement board according to the comparative example 2 as described in the Table 2. In addition, the boards are incombustible in terms of fire resistance. Furthermore, the weights per unit area of the boards according to the examples 2 to 4 are 1.0 to 1.3, which are similar to that (1.0 to 1.2) of the wood-wool cement board according to the comparative example 2.

[68] Moreover, the boards according to the examples 2 to 4 have excellent compression strength (500 kg/20cnf), and the submergence stabilities of the incombustible boards of the examples 2 to 4 are excellent, thereby shapes of the incombustible boards are stably maintained in water without being deformed. Mode for Invention

[69] Industrial Applicability

[70] As described above, the present invention provides an incombustible composition used to produce an access floor board. In this regard, 1 to 70 wt% of the incombustible composition may be made of a waste material. Accordingly, the incombustible composition of the present invention is advantageous in that the production costs are reduced, and that it is useful as a construction finishing and interior material, particularly, the access floor board because no fire and toxic gases occur when the incombustible composition is on fire.

[71] Other advantages are that the incombustible composition has excellent pro- cessability (saw processing, screwing, planing, attachment of floor tile, patterned wood, film, and imitation and native stones, coating, and the like), and that an incombustible construction product, produced using the incombustible composition, has excellent strength and water resistance. In addition, the incombustible construction product is not easily deformed, thereby being applied to construction interior/exterior materials having various functions, such as a far- infrared function. Therefore, the incombustible construction product provides various functions, such as the far-infrared function, to the access floor at normal times, but prevents a fire from spreading and shields persons from toxic gases generated by fire when the incombustible construction product is on fire, thereby providing a safe environment.

[72] The present invention has been described in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. Sequence List Text

[73]

Claims

[1] 1. An incombustible composition for an access floor board, comprising 1 to 90 wt% of stone powder, 1 to 30 wt% of curing fire-retardant resin, 1 to 80 wt% of organic or inorganic fiber, and 1 to 80 wt% of fly ash or bottom ash.

2. The incombustible composition as set forth in claim 1, wherein the curing fire- retardant resin is a phenol resin, a fire-retardant polyester resin, or a melamine resin.

3. The incombustible composition as set forth in claim 1, wherein the organic fiber is paper fragments shattered into fibroid materials, shattered wood fragments, waste fibers, wood powder, rice bran, Styrofoam particles, vegetable fibers, or a mixture thereof, and the inorganic fiber is rock wool, glass wool, basaltic wool, ceramic wool, or a mixture thereof.

4. The incombustible composition as set forth in claim 1, further comprising 1 to 80 wt% of the fire-proofing agent.

5. The incombustible composition as set forth in claim 4, wherein the fire- proofing agent is calcium carbonate, sodi n bicarbonate, sodi n carbonate, other carbonates, or a mixture thereof.

6. A method of producing an access floor board, comprising: providing the incombustible composition according to any one of claims 1 to 5; mixing a curing fire-retardant resin and a fly ash or bottom ash with each other; adding an organic or inorganic fiber into a mixture, shattering the mixture containing the organic or inorganic fiber, and mixing stone powder with the shattered mixture by use of a mixer using air; pressing the resulting mixture using a high pressure hot press to form a board; and finishing sides of the board.

7. The method as set forth in claim 6, further comprising the pressing of the resulting mixture is conducted while reinforcement meshes, made of a glass fiber, are spread in the high pressure hot press, or attaching a stainless steel, steel, or aliminυm plate to a backside of the board after the pressing of the resulting mixture so as to increase compression and tensile strengths of the board to reinforce the board.

8. The method as set forth in claim 6, wherein the finishing of sides of the board comprises attaching a fire-retardant floor material, an imitation stone, or a native stone to the board.

9. An incombustible access floor board produced according to the method of any one of claims 6 to 8. Abstract