JP2021062996A - Cement paste, method for producing cement paste, and fire-resistant wooden structural member - Google Patents

Abstract

To provide a cement paste capable of being applied to a structure part such as beams and pillars of a wooden building in a thickness making for fire resistance efficiency, without separately providing a framework.SOLUTION: A cement paste is used for a coating execution to a wooden structural member. The cement paste contains cement, water, and a fiber material, whereby the added fiber material enables viscosity and cohesiveness of the cement paste to be enhanced, or gelation can prevent the cement paste from dripping when the cement paste is applied to a vertical side surface of pillars and a beam material. Accordingly, the cement paste can be applied to a structure part such as beams and pillars of a wooden building in a thickness making for fire resistance efficiency.SELECTED DRAWING: None

Description

The present invention relates to a cement paste, a method for producing a cement paste, and a fire-resistant wooden structural member, and more particularly to a method for producing a cement paste for coating a wooden structural member, a method for producing a cement paste, and a fire-resistant wooden structural member.

Conventionally, steel frames and reinforced concrete are generally used for structural parts such as beams and columns that support the load of buildings other than wood, but from the viewpoint of enhancing forest metabolism and preserving forests, Proposals have been made to increase the proportion of wood as a structural material.

However, when wood is used as the structural material, there is a problem that the fire resistance performance is inferior to that of steel frames and the like. Patent Document 1 discloses a wooden building member having improved fire resistance. Specifically, the wooden building member of Patent Document 1 includes a long and short rectangular structural portion that receives a load, a covering portion that covers all four sides of the cross section of the structural portion over its entire length, and a structural portion and a covering portion. It has a gypsum board that intervenes between the two.

According to this, when a fire breaks out in a wooden building, the structural part is covered with gypsum board, so that it is not exposed to flames, carbonization progresses very slowly, and it does not burn out in a short time.

Japanese Patent No. 4359275

According to the wooden building material of Patent Document 1, the fire resistance performance is improved and the time from the occurrence of the fire to the collapse of the wooden building can be increased, but since it is necessary to use gypsum board, it will be commercialized. Storage equipment for gypsum board (and manufacturing equipment if necessary) is required, and since wooden building members are assembled at the site, it takes time and effort to transport the gypsum board to the site.

Therefore, in order to eliminate the trouble of storing and transporting gypsum board, the inventors considered applying cement paste on-site instead of gypsum board for the structural part that imparts fire resistance. When is added or when only fine aggregate such as sand and water are added to cement, the cement paste becomes sol-like, and when applied to the vertical side of the pillar material, a large amount of liquid drips occurs, and the required fire resistance is achieved. It was found that the coating thickness to be satisfied could not be secured.

Here, although it is possible to improve the coating thickness by providing a skeleton such as Takekomai, it will take additional time and effort to create the skeleton.

An object of the present invention made in view of the above problems is to provide a cement paste that can be applied to structural parts such as beams and columns of a wooden building with a thickness that contributes to fire resistance without separately providing a framework. is there.

The invention according to claim 1 for achieving the above object is a cement paste for coating construction on a wooden structural member, and is characterized by containing cement, water, and a fiber material.

According to the present invention, the added fiber material improves the viscosity and cohesiveness of the cement paste, or gels, thereby suppressing the liquid dripping that occurs when the cement paste is applied to the vertical side surface of the column / beam material. it can. Therefore, it is possible to apply the cement paste to the structural parts such as beams and columns of a wooden building with a thickness that contributes to fire resistance.

The invention according to claim 2 is characterized in that the cement paste according to claim 1 further contains silica sand.

According to the present invention, since the main component of the silica sand is silicon dioxide, the nonflammability of the obtained cured product is improved, oxygen permeation is suppressed by the silicon dioxide, and the internal structure covered with the cured product is suppressed. The burning of the body can also be delayed.

The invention according to claim 3 is characterized in that, in the cement paste according to claim 1 or 2, the cement is a non-shrink cement that forms crystals having hydrate when cured.

According to the present invention, since the cured product is strongly bonded to water in the form of hydrate, when a fire breaks out, the endothermic reaction during evaporation of the water lowers the ambient temperature, causing the cured product to be around the cured product. The combustion of the located structure can be delayed.

The invention according to claim 4 is the cement paste according to any one of claims 1 to 3, wherein the fiber material is 3600 in a 1.0% by mass aqueous NaOH solution having a liquid temperature of 50 ° C. ± 1 ° C. It is characterized in that a polymer material having a tensile strength after time immersion of 70% or more as compared with the tensile strength before immersion is used.

According to the present invention, where the inside of the cement paste is under strong alkaline conditions, the fiber material can maintain its strength even under strong alkaline conditions, so that the viscosity of the cement paste required for thick coating is maintained before curing. It is possible to maintain the strength of the obtained cured product after curing.

The invention according to claim 5 contains the water of 10 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the cement in the cement paste according to claim 1, and the fiber material is used as the total mass of the cement paste. It is characterized in that it is contained in a proportion of 0.2% by mass or more and 1.0% by mass or less with respect to the amount.

The present invention illustrates a suitable formulation of cement paste that does not contain silica sand, and according to this configuration, the viscosity of cement is improved or gelled by the fiber material, and the structure of beams, columns, etc. of wooden buildings It is possible to apply cement paste to the part with a thickness that contributes to fire resistance.

The invention according to claim 6 is the cement paste according to claim 2, which is 5 parts by mass or more and 20 parts by mass or less of water and 55 parts by mass or more and 70 parts by mass or less, respectively, with respect to 100 parts by mass of the cement. It is characterized by containing silica sand and containing the fiber material in a proportion of 0.05% by mass or more and 1.8% by mass or less with respect to the total mass of the cement paste.

The present invention exemplifies a suitable blending of cement paste containing silicon, and according to this configuration, the viscosity of cement is improved or gelled by the fibrous material, and structural parts such as beams and columns of wooden buildings are formed. It is possible to apply cement paste to a thickness that contributes to fire resistance.

The fire-resistant wooden structural member of the invention according to claim 7 is the cement paste according to any one of claims 1 to 6, which covers a columnar wooden structural member and a side peripheral surface of the wooden structural member. It is characterized by having a coated portion made of a cured product.

According to the present invention, since the side peripheral surface of the wooden building is covered with a covering material made of a cured product of a thickly coated cement paste, it is possible to provide a wooden structural member having improved fire resistance. In addition, since this covering material can be provided by applying the material constructed at the factory to the side peripheral surface of the wooden structural member at the cement paste site instead of transporting it to the site, conventional gypsum board or the like can be used. No storage space for large materials is required, and no manufacturing equipment for the large materials is required.

The method for producing a cement paste according to claim 8 is a method for producing a cement paste for coating on a wooden structural member, which comprises cement, water, a fiber material and silica sand, and is a powder containing cement and silica sand. A powder mixing step of mixing bodies (excluding fiber materials) to obtain a powder mixture, a first kneading step of adding the water to the powder mixture and kneading to obtain a kneaded product, and the kneading. It is characterized by including a second kneading step of adding the fiber material to a product and further kneading it to obtain a cement paste.

According to the present invention, the added fiber material improves the viscosity and cohesiveness of the cement paste, or gels, thereby suppressing the liquid dripping that occurs when the cement paste is applied to the vertical side surface of the column / beam material. it can. Therefore, it is possible to apply the cement paste to the structural parts such as beams and columns of a wooden building with a thickness that contributes to fire resistance.

Further, by passing through the powder mixing step, the first kneading step and the second kneading step by the method for producing a cement paste of the present invention, the dispersibility of each material is improved and the cement paste enables even thick coating. Can be provided.

According to the present invention, the added fiber material improves the viscosity and cohesiveness of cement, or gels, so that the liquid dripping that occurs when the cement paste is applied to the vertical side surface of the column / beam material can be suppressed. .. Therefore, it is possible to apply cement paste to structural parts such as beams and columns of wooden buildings with a thickness that contributes to fire resistance. As a result, it is possible to easily impart fire resistance to the structural part of a wooden building at the site as compared with the case of using a conventional gypsum board, and with the spread of the cement paste of the present invention, the structural part material The use of wood as a gypsum can be promoted.

<Cement paste>
The cement paste of the present invention is a cement paste for coating on a wooden structural member, and includes cement, water, and a fiber material.

The wooden structural member will be described later in the item of fire-resistant wooden structural member.

Cement is an inorganic bonding material that exhibits curability when kneaded with water, and in the present invention, hydraulic cement is used. As the hydraulic cement, simple cement such as Portland cement, hydraulic lime, Roman cement, or natural cement may be used, or mixed cement such as lime mixed cement or mixed Portland cement may be used.

Of these, the cement is preferably a non-shrinkable cement that forms crystals of cement hydrate upon hardening. In the present invention, the non-shrink cement refers to an expandable cement that expands to such an extent that the shrinkage of slightly shrinkable cement such as Portland cement can be offset.

Examples of the cement hydrate crystals include calcium aluminates hydrate, calcium silicate hydrate, and cement bacillus type, but cement bacillus type having a large amount of water of crystallization is particularly preferable. This is because the cured product of the cement paste contains a large amount of hydrate, so that the endothermic effect of the evaporation of water in the event of a fire can be further enhanced. The cement Bacillus system, for _{example, 3CaO · Al 2 O 3 ·} 3CaSO 4 · (30~32) H 2 O ( _{ettringite), 3CaO · Al 2 O 3} · CaSO 4 · 12H 2 O, 3CaO · Fe 2 O 3・ 3CaSO ₄・ 32H ₂ O, _{3CaO ・ Al 2} O ₃・ 3CaSiO ₃・ 12H ₂ O, _{3CaO ・ Al 2} O ₃・ 3CaSiO ₃・ 32H ₂ O, _{3CaO ・ Al 2} O ₃・ CaCl ₂・ 10H ₂ O, _{3CaO · Al 2 O 3 · CaCO} 3 · nH 2 O and the like.

In order to form crystals of cement hydrate during curing, it is possible to add a leavening agent to the cement, and examples of the leavening agent include a calcium salphoaluminate-based leavening agent that produces ettringite. Examples of the calcium sulfate-based leavening agent include a combination of tricalcium aluminate (C3A) and gypsum, a combination of free lime, hauyne, and anhydrous gypsum. Commercially available swelling agents include the lime-based swelling agent Pacific HyperExpan (manufactured by Pacific Materials), the ettringite-lime complex Super Sax (manufactured by Sumitomo Osaka Cement), and the ettringite-lime complex Denka Power CSA. (Made by Denka).

Commercially available non-shrink cements that form cement hydrate crystals when cured include Ssaber (manufactured by Nippon Steel & Sumitomo Metal Cement), MG-15M Super (manufactured by Mitsubishi Materials), and Groutmix F (manufactured by Tokuyama). , Non-shrink grout (manufactured by Shinko Co., Ltd.), etc.

The fiber material is added mainly for the purpose of imparting viscosity and cohesiveness to the cement paste. The fiber material may be any fiber material as long as it can impart viscosity and cohesiveness to the cement paste, and various fibers such as plant fiber, glass fiber, metal fiber, carbon fiber and polymer material fiber can be used. You can choose from. The fiber material also contributes to improving the strength of the cured product of the cement paste.

The fiber material preferably has a specific gravity close to that of cement paste from the viewpoint of dispersibility in the paste, and specifically, glass fiber, carbon fiber, or polymer material fiber, and further cost and strength. It is most preferable to use a polymer material fiber from the viewpoint of the above.

Further, since the fiber material is added to the highly alkaline cement paste and continues to exist even after curing, an alkali-resistant material is preferable from the viewpoint of maintaining strength after curing.

Specifically, a fiber material having a tensile strength of 70% or more after being immersed in a 1.0% by mass aqueous NaOH solution having a liquid temperature of 50 ° C. ± 1 ° C. for 3600 hours as compared with the tensile strength before the immersion is used. Is preferable.

The above-mentioned measurement of tensile strength and immersion test in a highly alkaline aqueous solution are carried out in Joint Research Report No. 168, pp. 10-13 (published by PWRI, Public Works, Ministry of Construction, March 1997) on technological development of mixed reinforced soil. It can be carried out with reference to the description.

Further, the tensile strength shall be measured by, for example, a method according to JIS L1013: 2010.

As a fiber material of a polymer material in which the tensile strength after being immersed in a 1.0% by mass concentration NaOH aqueous solution at a liquid temperature of 50 ° C. ± 1 ° C. for 3600 hours is 70% or more as compared with the tensile strength before the immersion. Examples include, but are not limited to, vinylon fibers, polypropylene fibers, and polyethylene fibers.

The length of the fiber material may be any length as long as it is not more than the coating thickness of the cement paste, but is preferably 1 μm or more and 3 mm or less, and more preferably 10 μm or more and 1 mm or less. ..

Further, the cement paste of the present invention preferably contains silica sand. Since the main component of silica sand is silicon dioxide, the nonflammability of the obtained cured product is improved, and the permeation of oxygen is suppressed by silicon dioxide, so that when the wooden structural member is covered with the cured product. Can delay the burning of wooden structural members.

As the silica sand, commercially available ones can be used, and those having a size of No. 2 to No. 8 can be used, and those of No. 4 to No. 6 are preferably used.

When the cement paste does not contain silica sand, it preferably contains 10 parts by mass or more and 20 parts by mass or less, particularly 13 parts by mass or more and 18 parts by mass or less of water with respect to 100 parts by mass of cement, and the fiber material is the whole cement paste. It is contained in a proportion of 0.2% by mass or more and 1.0% by mass or less, particularly 0.2% by mass or more and 0.6% by mass or less with respect to the mass.

On the other hand, when silica sand is contained, the cement paste is preferably 5 parts by mass or more and 20 parts by mass or less, particularly 10 parts by mass or more and 20 parts by mass or less of water with respect to 100 parts by mass of cement, and 100 parts by mass of cement. 55 parts by mass or more and 70 parts by mass or less, particularly 57 parts by mass or more and 65 parts by mass or less of silica sand, and the fiber material is 0.05% by mass or more and 1.8% by mass or less based on the total mass of the cement paste. In particular, it is contained in a ratio of 0.1 part by mass or more and 1.0 part by mass or less.

The cement paste of the present invention may contain other components in addition to the cement, water, fiber material, silica sand, and leavening agent. Other components that can be contained in the cement paste of the present invention include thickeners (cellulosic thickeners, protein thickeners, etc.) and defoamers (silicone defoamers, mineral oil defoamers, etc.). Agents, etc.), known and commonly used additives such as setting retarders.

<Manufacturing method of cement-based grout material>
The present invention also provides a method for producing a cement-based grout material for coating on a wooden structural member, which contains cement, water, a fiber material and silica sand.

The method for producing a cement-based grout material of the present invention includes a powder mixing step, a first kneading step, and a second kneading step.

[Powder mixing process]
The powder mixing step is a step of mixing a powder containing cement and silica sand (however, excluding a fibrous material) to obtain a powder mixture. In this step, a hand mixer, a pan-type mixer, etc., which are well-known in the present technical field, can be used, and as a condition, the dry kneading is performed for about 30 seconds to 2 minutes under the dry kneading condition in which water is not added to the material. It is carried out by.

[First kneading process]
The first kneading step is a step of adding water to the powder mixture obtained in the powder mixing step and kneading the mixture to obtain a kneaded product. The above-mentioned hand mixer, bread type mixer and the like can be used as they are for kneading, and conditions suitable for each mixer can be appropriately selected for the kneading speed and kneading time. As an example, water can be added and kneading can be further carried out for about 30 seconds to 2 minutes.

[Second kneading process]
The second kneading step is a step of adding a fiber material to the kneaded product obtained in the first kneading step and further kneading the kneaded product to obtain a cement paste. The second kneading step can be carried out as it is using the mixer used in the first kneading step.

A suitable amount of the fiber material may be determined in advance, and the amount may be added and kneaded. However, the fiber material is added little by little and kneaded for a certain period of time, and when the desired viscosity is obtained, the fiber material is kneaded. It may be added, kneaded and stopped. As an example, after adding the fiber material, kneading can be performed for about 1 to 3 minutes.

According to the method for producing a cement paste of the present invention, it is possible to obtain a cement paste having excellent dispersibility of compounding components and having cohesiveness and adhesiveness suitable for coating.

<Fireproof wooden structural member>
The fire-resistant wooden structural member of the present invention has a columnar wooden structural member and a coated portion of a cured product of the cement paste of the present invention that covers the side peripheral surface of the wooden structural member.

The wooden structural member is a columnar wooden member used for the frame of a building, and when it is provided in the vertical direction in the building, it becomes a pillar, and when it is provided in the horizontal direction, it becomes a beam. The shape may be a cylinder, and various shapes such as a cylinder, a quadrangular prism, a truncated cone, and an inverted truncated cone can be mentioned.

Further, the wooden structural member may be formed in any way as long as it has a necessary strength in consideration of various loads such as the weight of the building and external forces such as snow cover, wind, and earthquake. For example, it may be formed from a single log or may be compression molded. Further, it may be a laminated wood formed by adhesively laminating a wood board cut to a predetermined size or a compressed material thereof.

Cement paste is applied to the side peripheral surface of this wooden structural member, and a covering portion is formed by the cured product.

From the viewpoint of improving the fire resistance of the wooden structural member, the covering portion is preferably provided over the entire circumference of the side peripheral surface of the wooden structural member, but from an economical point of view, it is easily affected by fire. The covering portion may be provided only on the surface (for example, the side peripheral surface on the indoor side of the building or the side peripheral surface on the outdoor side of the building).

The thickness of the covering portion may be 1 cm or more, preferably 2 cm or more, and particularly preferably 3 cm or more, from the viewpoint of improving fire resistance. Here, as the thickness of the covering portion, the shrinkage of the cement paste is not taken into consideration in the present specification, and the coating thickness immediately after the application of the cement paste is expressed as the thickness of the covering portion as it is.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

For example, in the fire-resistant wooden structural member of the present invention, the columnar wooden structural member is covered with a covering portion, but the covering portion itself may be further covered with a decorative board material or the like. According to this, not only the design of the fire-resistant wooden structural member is improved, but also the decorative plate material is the flammable part in the event of a fire, and the covering part is the burn-out part that secures the fire resistance of the structural member, and the inside. The wooden structural member can play each role of a load support portion that guarantees the strength as a structural material.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

<1. Preparation of cement paste of Examples 1 to 3 and Comparative Example 1>
1-1. Example 1
1.5 parts by mass of water was added to 10 parts by mass of cement (Ssaber, manufactured by Nippon Steel & Sumikin Cement Co., Ltd.), and kneaded for 1 minute using a hand mixer (UT1305, manufactured by Makita Co., Ltd.). 0.03 parts by mass of a fiber material (Powerlon RM182 × 6D) was added to the obtained kneaded product and further kneaded with the above hand mixer for 2 minutes to obtain the cement paste of Example 1.

1-2. Example 2
Mix 11.1 parts by mass of cement (Ssaber, manufactured by Nippon Steel & Sumikin Cement) and 6.67 parts by mass of silica sand (Sisago No. 5, manufactured by JFE Minerals), and use a hand mixer (UT1305, manufactured by Makita). Dry kneading (mixing) was performed for 30 seconds. 2.08 parts by mass of water was added to the obtained powder mixture, and kneading was carried out for another 1 minute with the above hand mixer. To the obtained kneaded product, 0.083 parts by mass of a fiber material (Cratec RF 4000 × 30 mm, manufactured by Kuraray Co., Ltd.) was added and kneaded with the above hand mixer for another 2 minutes to obtain the cement paste of Example 2.

1-3. Example 3
11.05 parts by mass of cement (Ssaber, manufactured by Nippon Steel & Sumikin Cement Co., Ltd.) and 6.96 parts by mass of silica sand (Silica Sand No. 5, manufactured by JFE Mineral Co., Ltd.) were mixed. 1.98 parts by mass of water was added to the obtained powder mixture and kneaded. 0.03 parts by mass of a fiber material (ZL 59dtex × 6 mm, manufactured by Daiwabo Co., Ltd.) was added to the obtained kneaded product and further kneaded to obtain the cement paste of Example 3. The apparatus used and the stirring conditions are the same as in Example 2.

1-4. Comparative Example 1
1.86 parts by mass of water was added to 8.75 parts by mass of cement (Ssaber, manufactured by Nippon Steel & Sumikin Cement Co., Ltd.) and kneaded to obtain the cement paste of Comparative Example 1. The apparatus used and the kneading conditions are the same as in Example 1.

<Thick coating test>
<1. Adjusting the cement pastes of Examples 1 to 3 and Comparative Example 1>, the cement pastes prepared are troweled on the side surfaces of a plate having a width of about 30 cm and a height of about 60 cm, which are provided vertically. The thickness that could be applied was evaluated according to the following criteria.

◎ 3 cm or more ○ 2 cm or more and less than 3 cm △ 1 cm or more and less than 2 cm × less than 1 cm

The results of the thick coating test are shown in Table 1.

From the results shown in Table 1, it can be seen that the cement paste containing the fiber material of the example can have a coating thickness of at least 1 cm or more on the plate material.

Claims (8)

A cement paste for application to wooden structural members.
A cement paste characterized by containing cement, water, and a fibrous material. The cement paste according to claim 1, further comprising silica sand. The cement paste according to claim 1 or 2, wherein the cement is a non-shrinkable cement that forms crystals having hydrates when cured. As the fiber material, a polymer material having a tensile strength of 70% or more after being immersed in a 1.0% by mass aqueous NaOH solution having a liquid temperature of 50 ° C. ± 1 ° C. for 3600 hours as compared with the tensile strength before the immersion is used. The cement paste according to any one of claims 1 to 3, wherein the cement paste is used. Contains 10 parts by mass or more and 20 parts by mass or less of the water with respect to 100 parts by mass of the cement.
The cement paste according to claim 1, wherein the fiber material is contained in a proportion of 0.2% by mass or more and 1.0% by mass or less with respect to the total mass of the cement paste. Each 100 parts by mass of the cement contains water of 5 parts by mass or more and 20 parts by mass or less and silica sand of 55 parts by mass or more and 70 parts by mass or less.
The cement paste according to claim 2, wherein the fiber material is contained in a proportion of 0.05% by mass or more and 1.8% by mass or less with respect to the total mass of the cement paste. Columnar wooden structural members and
A covering portion made of a cured product of the cement paste according to any one of claims 1 to 6, which covers the side peripheral surface of the wooden structural member.
A refractory wooden structural member characterized by having. A method for producing a cement paste for coating on wooden structural members, which contains cement, water, fiber material and silica sand.
A powder mixing step of mixing powders containing cement and silica sand (excluding fiber materials) to obtain a powder mixture, and
The first kneading step of adding the water to the powder mixture and kneading to obtain the kneaded product, and
The second kneading step of adding the fiber material to the kneaded product and further kneading to obtain a cement paste, and
A method for producing a cement paste, which comprises.