Refractory coating material and method for forming refractory coating

Abstract

To provide a fire-resistant coating material and a method for forming a fire-resistant coating on structural materials that offers good sprayability and also takes life cycle assessment measures into consideration. [Solution] A fire-resistant coating material for spraying onto structural materials, comprising (A) rock wool, (B) blast furnace slag, and (C) a slurry containing ordinary cement, wherein the ordinary cement content in the slurry is 1% by mass or more and less than 30% by mass in terms of solid content.

Description

Technical Field

[0001] The present invention relates to a fireproof coating material and a method for forming a fireproof coating on a structural material.

Background Art

[0002] As a fireproof coating means for structural materials such as columns and beams of buildings, a rock wool spraying method in which rock wool and ordinary cement slurry are mixed and sprayed is widely used. And as the spraying means, there are a dry method, a wet method, and a semi-dry method. In these spraying methods, from the viewpoints such as dust generation during the spraying operation, large work load during the spraying operation, and safety, studies have been conducted to set the usage ratio of rock wool to a specific amount (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional spraying method, in addition to reducing the work load during the spraying operation, life cycle assessment measures such as reducing the CO2 emission amount per unit are insufficient. Therefore, an object of the present invention is to provide a fireproof coating material and a method for forming a fireproof coating on a structural material, which have good spraying workability and also take into account life cycle assessment measures.

Means for Solving the Problems

[0005] Therefore, the inventors of the present invention investigated how to solve the aforementioned problems and found that by reducing the amount of ordinary cement, which is a hydraulic material, and replacing it with a large amount of blast furnace slag, they were able to obtain a refractory coating material with sufficient strength that did not cause blockage or pumping problems in the hose due to sedimentation during spraying work, thus completing the present invention.

[0006] In other words, the present invention provides the following [1] to [6]. [1] A fire-resistant coating material for spraying onto structural materials, comprising (A) rock wool, (B) blast furnace slag, and (C) a slurry containing ordinary cement, wherein the ordinary cement content in the slurry is 1% by mass or more and less than 30% by mass on a solid content basis. [2] The refractory coating material according to [1], wherein the blast furnace slag content in the slurry is more than 70% by mass and 99% by mass or less in terms of solid content, and the ordinary cement content is 1% by mass or more and less than 30% by mass. [3] The refractory coating material according to [1] or [2], wherein the blast furnace slag content in the slurry is 75% to 99% by mass in terms of solid content, and the ordinary cement content is 1% to 25% by mass. [4] The fire-resistant coating material according to any one of [1] to [3], wherein the slurry further contains gypsum. [5] The refractory coating material according to [4], wherein the amount of gypsum in the slurry, on an anhydrous gypsum basis, is 1% to 20% by mass relative to the blast furnace slag. [6] A method for forming a fire-resistant coating on a structural material, characterized by spraying the structural material with any of the fire-resistant coating materials described in [1] to [5]. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce the amount of ordinary cement used, which has a high CO2 emission intensity, and to obtain a fire-resistant coating material that does not cause blockage or poor pumping in the hose due to sedimentation during spraying work, while also having sufficient strength. [Brief explanation of the drawing]

[0008] [Figure 1] The slurry sedimentation rate measurement results are shown. [Figure 2] The results of slurry sedimentation rate measurements using different types of gypsum are shown. [Figure 3] The results of the compressive strength test are shown. [Modes for carrying out the invention]

[0009] Terms used herein shall be used in the sense commonly used in the art unless otherwise specified.

[0010] One aspect of the present invention is a fire-resistant coating material for spraying onto structural materials, comprising (A) rock wool, (B) blast furnace slag, and (C) a slurry containing ordinary cement, wherein the ordinary cement content in the slurry is 1% by mass or more and less than 30% by mass on a solid content basis.

[0011] In the present invention, rock wool (A) used is preferably rock wool (also called rock wool, slag wool, or mineral wool) which is produced by melting natural stones such as blast furnace slag, basalt, andesite, and diabase, which are by-products of blast furnaces in steel mills, in a cupola, electric furnace, etc., and then blowing them into fibers using fluid pressure such as centrifugal force, air, or steam. The fiber diameter, shape, and particle size in the case of granular form are not particularly limited and can be used.

[0012] The slurry used in the present invention contains (B) blast furnace slag and (C) ordinary cement, wherein the ordinary cement content in the slurry is 1% by mass or more and less than 30% by mass in terms of solid content. Here, (B) blast furnace slag is slag produced as a by-product when iron ore is melted and reduced in a blast furnace. It is a mixture of non-iron components such as silica contained in the iron ore and the ash content of coke used as a reducing agent, combined with limestone, which is a secondary raw material. Among blast furnace slags, water-granulated slag, which is blast furnace slag fine powder, is preferred. As such, blast furnace slag is a by-product of the blast furnace and has a significantly lower CO2 emission intensity compared to ordinary cement. From the viewpoint of life cycle assessment, slurry settling rate and slurry settling rate, and good hardening rate, the blast furnace slag content in the slurry is preferably more than 70% by mass and 99% by mass or less in terms of solids, more preferably 71% to 99% by mass, even more preferably 74% to 99% by mass, even more preferably 78% to 96% by mass, and even more preferably 80% to 93% by mass.

[0013] (C) As for ordinary cement, Portland cements such as ordinary Portland cement, high-early-strength Portland cement, and white cement are used, as well as eco-cement manufactured using municipal solid waste incineration ash and sewage sludge incineration ash as the main raw materials. From the viewpoint of life cycle assessment, slurry settling rate and slurry settling rate, and good hardening rate, the content of ordinary cement in the slurry is 1% by mass or more and less than 30% by mass in terms of solid matter, preferably 1% to 25% by mass, more preferably 1% to 20% by mass, even more preferably 1% to 10% by mass, and even more preferably 1% to 5% by mass.

[0014] In the present invention, it is preferable to include (D) gypsum in the slurry from the viewpoint of life cycle assessment, slurry settling rate and slurry settling speed, good curing speed, and especially good curing speed. Examples of gypsum include dihydrate gypsum, waste gypsum, and anhydrous gypsum, but it is preferable to use dihydrate gypsum or waste gypsum. Furthermore, excavated dihydrate gypsum can also be used as dihydrate gypsum, and waste gypsum is generally made from dry-ground gypsum board waste with the reinforcing paper removed. The amount of gypsum in the slurry, in terms of anhydrous gypsum equivalent, is preferably 1% to 20% by mass relative to the blast furnace slag, more preferably 1% to 15% by mass, even more preferably 4% to 15% by mass, and even more preferably 6% to 15% by mass, from the viewpoint of slurry settling rate and slurry settling velocity, and good hardening rate, and especially good hardening rate.

[0015] In addition to the above components, the slurry can contain a fluidizing agent and a surfactant. Examples of the fluidizing agent include naphthalene-based fluidizing agents, polycarboxylic acid-based fluidizing agents, and melamine-based fluidizing agents. The content of the fluidizing agent, surfactant, etc. is preferably 0.1% to 2% by mass on an external basis with respect to the solid content conversion amount.

[0016] The slurry concentration (total concentration of solid components such as the components (B), (C), (D), etc. in the slurry) is preferably 30 to 60% by mass, more preferably 40 to 60% by mass, and even more preferably 40 to 50% by mass from the viewpoint of pumping property.

[0017] The refractory coating material of the present invention is formed by spraying a mixture of the slurry and rock wool onto a structural material. Therefore, another aspect of the present invention is a method for forming a refractory coating on a structural material, characterized by spraying a refractory coating material containing the (A) rock wool, (B) blast furnace slag, and (C) ordinary cement-containing slurry onto the structural material. Here, examples of the structural material include building structures, particularly beams, columns, walls, etc. of steel frame buildings.

[0018] As the spraying method of the refractory coating material of the present invention, any of a dry method, a wet method, and a semi-dry method may be used, and the semi-dry method is particularly preferred. The dry method is a method in which a powder containing (A) rock wool, (B) blast furnace slag, and (C) ordinary cement is discharged from a spraying nozzle in advance, and at the same time, water is separately fed and discharged from an injection port arranged at the spraying nozzle, and the two are mixed and sprayed. The wet method is a method in which water is added to a powder containing the above (A) rock wool, (B) blast furnace slag, (C) ordinary cement, etc., kneaded with a mixer to form a slurry, and this is pumped by a pump and sprayed from a spraying nozzle by compressed air. The semi-dry method is a method in which water is added to a powder containing (A) rock wool, (B) blast furnace slag, (C) ordinary cement, etc., kneaded with a mixer to form a slurry, and the slurry is separately fed and mixed and sprayed at the spraying nozzle portion.

[0019] In the present invention, when spraying, the mixing ratio of (A) rock wool and the solid components in the slurry, including (B) blast furnace slag and (C) ordinary cement, is preferably such that the mass ratio of rock wool to solid components in the slurry is 1.5:1 to 1:1.5, more preferably 1.35:1 to 1:1.35, and even more preferably 1.2:1 to 1:1.2. [Examples]

[0020] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0021] Test Example 1 (Slurry Settlement Rate) A rapid slurry settling rate could lead to blockages or poor pumping in the hose during spraying, potentially negatively impacting spraying performance. Therefore, we conducted a check to confirm this. (1) Test level Table 1 shows the test specimen levels. The slurry settling rate was confirmed using the blast furnace slag (BFS) replacement rate, the presence or absence of SO3 added to the gypsum in relation to the blast furnace slag, and the type of gypsum as factors. Regarding the type of gypsum, dihydrate gypsum was used as the basis, but waste gypsum was also examined to confirm differences in gypsum types.

[0022] [Table 1]

[0023] (2) Test method 200 mL of the slurry immediately after preparation was poured into a graduated cylinder, and the time when the pouring was completed was defined as the start time of the test. The amount of slurry settling over time was then observed. The slurry sedimentation rate was determined by checking the volume that settled from the initial slurry volume (200 mL) and dividing the settled volume by the initial slurry volume. (3) Measurement results of slurry settling rate The slurry settling rate measurement results are shown in Figures 1-3. Here, regarding the relationship between the BFS replacement rate and the amount of SO3, based on the reference (Kobayashi, Uomoto, "Method of Utilization of Slag Gypsum Cement", Production Research 1981, Vol. 33, No. 6, pp. 228-231), the optimal BFS replacement rate was set to 8% in terms of SO3 amount, and added to the BFS in a proportional ratio. Figures 1-3 show that a lower blast furnace slag replacement rate tended to result in a higher initial settling rate. A higher blast furnace slag replacement rate resulted in a lower initial settling rate, but a higher final settling rate. Furthermore, there was no significant difference in settling rate with SO3 addition in dihydrate gypsum. The settling rate varied significantly depending on the type of gypsum (dihydrate gypsum and waste gypsum). Compared to waste gypsum, it settled more slowly and tended to have a lower final settling rate.

[0024] Test Example 2 (Compression Strength Test) If the hardened material does not develop strength after spraying, there is a risk of damage or detachment of the fire-resistant coating material. Therefore, a compressive strength test was conducted to confirm the development of strength. (1) Test specimen Table 2 shows the compressive strength test specimen levels. The test specimens consist of rock wool (RW) and slurry solids in a 1:1 ratio with a bulk density of 0.40 g / cm³. 3 The material was measured and filled into a mold to produce the product.

[0025] [Table 2]

[0026] (2) Test method The prepared test specimens were cured indoors for 1, 7, 14, and 28 days. After curing, they were dried at 40°C until a constant weight was reached, and then cut into 50 × 50 × 50 mm pieces. Compressive strength was defined as the compressive stress at which the compressive deformation rate reached 10% or at which compressive failure occurred at a loading rate of 5 mm / min.

[0027] (3) Results The results of the compressive strength test are shown in Figure 4. After a 28-day curing period, the compressive strength was highest with 100% ordinary cement (OPC), followed by a mixture of 1% OPC, 82% BFS, and 17.0% waste gypsum, which achieved approximately 80% compressive strength. Furthermore, a mixture of 1% OPC and 99% BFS achieved approximately 45% compressive strength.

Claims

1. A fire-resistant coating material for spraying onto structural materials, comprising (A) rock wool, (B) blast furnace slag, and (C) a slurry containing ordinary cement, wherein the ordinary cement content in the slurry is 1% by mass or more and less than 30% by mass on a solid content basis.

2. The refractory coating material according to claim 1, wherein the blast furnace slag content in the slurry is more than 70% by mass and 99% by mass or less in terms of solid content, and the ordinary cement content is 1% by mass or more and less than 30% by mass.

3. The refractory coating material according to claim 1, wherein the blast furnace slag content in the slurry is 75% to 99% by mass in terms of solid content, and the ordinary cement content is 1% to 25% by mass.

4. The fire-resistant coating material according to claim 1, wherein the slurry further contains gypsum.

5. The refractory coating material according to claim 4, wherein the amount of gypsum in the slurry, on an anhydrous gypsum basis, is 1% to 20% by mass relative to the blast furnace slag.

6. A method for forming a fire-resistant coating on a structural material, characterized by spraying the structural material with a fire-resistant coating material described in any one of claims 1 to 5.

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