Ceramic-based building material, and method of producing ceramic-based building material

Abstract

To provide a ceramic-based building material that can be produced under curing conditions at ordinary temperature and ordinary pressure and has desirable quality.SOLUTION: A ceramic-based building material includes magnesium oxide, magnesium hydroxide, aggregate, and pulp and does not substantially include a component derived from cement, with the content (mass%) of magnesium hydroxide being at least 24.8% relative to the content (mass%) of magnesium oxide.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a ceramic building material and a method for manufacturing a ceramic building material. [Background technology]

[0002] 2. Description of the Related Art Conventionally, as raw materials for ceramic building materials used for the exterior and interior walls and roofs of buildings, materials containing a cement component as a hardening agent have been known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-126294 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, efforts to realize a low-carbon society have become more active, and there is a demand for reducing CO2 emissions and improving energy efficiency in the manufacture of ceramic building materials. However, when cement components are used as hardeners for ceramic building materials, high-temperature steam curing or high-temperature, high-pressure steam curing is used as the curing condition, aiming to shorten the curing time and improve the quality. Therefore, there is a demand for technology that contributes to reducing CO2 emissions and improving energy efficiency.

[0005] The present invention has been made in view of the above, and an object of the present invention is to provide a ceramic building material that can be produced under curing conditions at room temperature and normal pressure and has preferable quality. [Means for solving the problem]

[0006] The present disclosure relates to a ceramic building material that includes magnesium oxide, magnesium hydroxide, aggregate, and pulp, is substantially free of cement-derived components, and has a magnesium hydroxide content (mass%) of 24.8% or more relative to the magnesium oxide content (mass%). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] <Ceramic building materials> The ceramic building material according to this embodiment can be cured at room temperature and pressure, and absorbs CO2 during curing, which contributes to improving energy efficiency and reducing CO2 emissions. In addition, it has physical strength equal to or greater than that of conventional ceramic building materials made from cement, and has excellent fire resistance.

[0008] The uses of the ceramic building materials are not particularly limited, but they can be used, for example, as decorative panels for the exterior or interior walls of buildings, roofing materials, and the like.

[0009] The ceramic building material according to the present embodiment contains magnesium oxide, magnesium hydroxide, aggregate, and pulp. In addition, it is preferable that the ceramic building material contains magnesium carbonate.

[0010] (Magnesium oxide) Magnesium oxide (MgO) is a component contained in ceramic building materials, as well as in compositions that are raw materials for ceramic building materials before hardening, and in raw material slurries. The content of magnesium oxide in ceramic building materials is 20 to 60 mass%. Magnesium oxide includes light-burned magnesium oxide and heavy-burned magnesium oxide, and is not particularly limited, but it is preferable to use light-burned magnesium oxide. Light-burned magnesium oxide has superior reactivity compared to heavy-burned magnesium oxide.

[0011] (Magnesium hydroxide) Magnesium hydroxide (Mg(OH)2) is produced by a hydration reaction of magnesium oxide contained in the composition and the raw material slurry, and is contained in the ceramic building material. It is believed that the strength of the ceramic building material is expressed by the production of magnesium hydroxide. The content (mass%) of magnesium hydroxide in the ceramic building material is 24.8% or more relative to the content (mass%) of magnesium oxide. The content of magnesium hydroxide in the ceramic building material is preferably 8% or more by mass.

[0012] Since magnesium hydroxide is a compound having flame retardancy, by including a certain amount or more in a ceramic building material, the fire resistance of the ceramic building material can be improved. In the case of a ceramic building material using conventional cement, a flame retardant needs to be mixed in order to improve the fire resistance, which may result in a decrease in quality and an increase in cost. In the ceramic building material according to the present embodiment, it is not necessary to mix a flame retardant in order to improve the fire resistance. Therefore, the decrease in quality and the increase in cost can be suppressed.

[0013] (Magnesium Carbonate) Magnesium carbonate (MgCO3) is produced by the carbonation of magnesium hydroxide and is contained in ceramic building materials. In the process of producing magnesium carbonate, CO2 is absorbed into the ceramic building material. Furthermore, the production of magnesium carbonate improves the strength of the ceramic building material. Magnesium carbonate can be produced during the normal curing of the raw material slurry under normal temperature and pressure, or after hardening, but curing the raw material slurry in a CO2 atmosphere promotes carbonation and allows more magnesium carbonate to be produced.

[0014] The content (mass%) of magnesium carbonate in the ceramic building material is preferably 15% or more relative to the content (mass%) of magnesium hydroxide. This provides a favorable CO2 absorption effect and favorable strength of the ceramic building material. From the above viewpoint, the content (mass%) of magnesium carbonate is more preferably 67.1% or more relative to the content (mass%) of magnesium hydroxide. The content of magnesium carbonate in the ceramic building material is preferably 10.0% or more by mass.

[0015] (aggregate) The aggregate is preferably at least one of lightweight aggregate and silica stone. Examples of lightweight aggregate include perlite, pumice, and shirasu balloons. The content of aggregate in the ceramic building material is preferably 5 to 20 mass %.

[0016] (pulp) Pulp is used to improve the strength of the ceramic building material according to this embodiment. The pulp is not particularly limited, but may be various pulp materials such as wood pulp such as N-wood pulp and L-wood pulp, waste paper pulp, mechanical pulp, chemical pulp, etc. The content of pulp in the ceramic building material is preferably 3 to 15 mass%.

[0017] The ceramic building material according to the present embodiment may contain other components in addition to those described above. Examples of the other components include silica sand and waste materials.

[0018] (silica sand) Silica sand is a sandy material whose main component is silicon dioxide (SiO2). Silica sand is preferably used because it has low water absorption, high strength and durability, and high chemical stability. There are no particular limitations on the type of silica sand, but examples include artificial silica sand produced by crushing and classifying quartz, and natural silica sand collected and classified in the form of quartz sand from land, river mouths, coasts, etc.

[0019] (scrap material) The waste material is at least one selected from the group consisting of fly ash, blast furnace slag, silica fume, and recycled material (crushed waste material generated in the manufacturing process of the hardened body).

[0020] The ceramic building material according to the present embodiment may contain, in addition to the above components, known components that may be contained in ceramic building materials, within the scope of the present disclosure. For example, aggregates such as fine aggregates and coarse aggregates other than those described above, mica, reinforcing fibers (polypropylene, etc.), wood fibers, water repellents, water reducing agents, retarders, foaming agents, defoamers, etc. may be contained.

[0021] The ceramic building material according to the present embodiment is cured and hardened under normal temperature and pressure, and therefore does not substantially contain any cement-derived components. In this specification and claims, the term "cement-derived components" refers to unhardened or hardened cement, and does not include recycled materials. In this specification and claims, "substantially does not contain any cement-derived components" means that the content of cement-derived components in the ceramic building material is 1 mass% or less. The ceramic building material according to the present embodiment may not contain any cement-derived components at all.

[0022] <Method of manufacturing ceramic building materials> The method for producing a ceramic building material according to this embodiment includes a preparation step, a slurry production step, a molding step, and a curing step for curing the molded raw material slurry.

[0023] (Preparation process) The preparation step is a step of preparing a composition containing magnesium oxide, aggregate, and pulp. The components contained in the composition are the same as those exemplified in the description of the ceramic building material, and may contain components other than those mentioned above.

[0024] (Slurry manufacturing process) The slurry production step is a step of adding water to the composition prepared in the preparation step and kneading to produce a raw material slurry. The slurry production step is not particularly limited, and a known method using a mixer or the like can be applied.

[0025] (molding process) The molding step is a step of molding the raw material slurry obtained in the slurry production step. The molding step is not particularly limited, and known methods such as extrusion molding, cast molding, paper molding, and press molding can be applied.

[0026] (Curing process) The curing step is a step of curing and curing the raw material slurry formed in the molding step to obtain a hardened body (ceramic building material). The curing step according to this embodiment can be performed under normal temperature and pressure. Furthermore, the curing step can be performed under normal humidity. This can reduce the energy required for manufacturing the ceramic building material. In this embodiment, normal temperature means 5 to 35°C, normal pressure means atmospheric pressure, and normal humidity means 45 to 85% RH. On the other hand, the curing step can also be performed under high temperature and normal pressure (for example, 50 to 90°C, humidity of 90% RH or more), but from the viewpoint of energy efficiency, it is preferable to perform the curing step under normal temperature and pressure.

[0027] In addition to the above, the curing step is preferably carried out in the presence of a predetermined concentration of CO2. It is more preferable to carry out the curing in an atmosphere with a CO2 concentration of 5% by volume or more. This can promote the carbonation of magnesium hydroxide contained in the hardened body, improving the strength of the hardened body and allowing more CO2 to be absorbed by the hardened body. As a method for curing the raw material slurry in the presence of a predetermined concentration of CO2, for example, a method of covering the raw material slurry with a cover or sheet and supplying CO2 into the inside can be mentioned.

[0028] The above is one example of a method for producing a ceramic building material according to this embodiment, and other steps known as methods for producing a ceramic building material may be included as long as they do not impair the effects of the present disclosure.

[0029] The ceramic building material and the manufacturing method thereof according to the embodiment of the present disclosure have been described above. However, the present disclosure is not limited to the above embodiment and can be appropriately modified. EXAMPLES

[0030] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0031] [Preparation of composition and raw material slurry] The compositions according to the Examples, Experimental Examples, and Comparative Examples were mixed and prepared in the ratios shown in Table 1. Then, 350 parts by mass of water was added and kneaded to obtain raw material slurries according to the Examples and Comparative Examples. The values ​​indicating the content of each component in Table 1 refer to parts by mass. The following materials were used as shown in Table 1. Cement: ordinary Portland cement, aggregate: perlite, pulp: virgin pulp, waste paper, waste material: a mixture of fly ash and crushed waste material (recycled material) generated during the manufacturing process of the hardened body.

[0032] [Regulation] The raw material slurry prepared above was molded by pouring it into a mold, and cured by the curing method shown in Table 1 to obtain a hardened body. Specifically, in Examples 1, 3, and 4, curing was performed for 12 hours under conditions of 25°C, relative humidity 50%, and atmospheric pressure. In Example 2, curing was performed for 12 hours under conditions of 25°C, relative humidity 50%, atmospheric pressure, and a CO2 concentration of 5 volume %. In Experimental Example 1, curing was performed for 6 hours under conditions of 60°C, relative humidity 90%, and atmospheric pressure. In Comparative Example 1, curing was performed for 8 hours in an autoclave set at 170°C (pressure about 0.8 MPa).

[0033] [Table 1]

[0034] [Measurement of each component in the hardened body] (Magnesium hydroxide (Mg(OH)2)) For samples in which the presence of magnesium hydroxide (Mg(OH)2) was confirmed by X-ray diffraction, thermogravimetric analysis was performed at a heating rate of 20°C / min, in a temperature range of 25 to 1000°C, in a N2 gas atmosphere. The weight loss in the range of 200°C to 400°C in the thermogravimetric analysis was regarded as a dehydration reaction of the Mg(OH)2 contained in each hardened body, and the mole number of Mg(OH)2 was calculated from the weight loss rate to determine the content (mass%).

[0035] (Magnesium carbonate (MgCO3)) The amount of carbon contained in each hardened body was determined using an elemental analyzer (CHN coder), and the CO2 content of the CO2 cured sample (Example 2) was calculated from the difference between the carbon amount of the CO2 cured sample (Example 2) and the carbon content of the non-CO2 cured sample. This was converted into magnesium carbonate (MgCO3) content and the content (mass%) was calculated.

[0036] <Evaluation Results> [Bending strength] The bending strength of the cured bodies according to the above-mentioned Examples and Comparative Examples was measured according to the methods in accordance with JIS A 5422 and JIS A 1408. The results are shown in Table 1.

[0037] [Fire resistance shrinkage rate] The fire shrinkage was measured using the hardened bodies according to the above examples and comparative examples. The measurement was performed by heating each hardened body for 1 hour under the condition of 1000°C using an electric furnace, and measuring the vertical and horizontal dimensions of each hardened body after cooling to room temperature. The fire shrinkage was calculated as the rate of change of the dimensions of each hardened body after heating to the dimensions before heating. The lower the fire shrinkage, the better the fire resistance. The results are shown in Table 1.

[0038] From the results shown in Table 1, it is clear that the hardened bodies of each Example have bending strength equal to or greater than that of the hardened bodies using conventional cements of the Comparative Examples, and a lower fire shrinkage rate.

Claims

1. The present invention relates to a cement-derived composite material that includes magnesium oxide, magnesium hydroxide, aggregate, and pulp, and is substantially free of any cement-derived components. A ceramic building material, in which the magnesium hydroxide content (mass %) relative to the magnesium oxide content (mass %) is 24.8% or more.

2. Further comprising magnesium carbonate, 2. The ceramic building material according to claim 1, wherein the content (mass%) of magnesium carbonate relative to the content (mass%) of magnesium hydroxide is 15% or more.

3. 3. The ceramic building material according to claim 1, wherein the content of magnesium hydroxide in the ceramic building material is 8% by mass or more.

4. Further comprising magnesium carbonate, 3. The ceramic building material according to claim 1, wherein the content of magnesium carbonate in the ceramic building material is 10 mass% or more.

5. 3. The ceramic building material according to claim 1 or 2, further comprising at least one waste material selected from the group consisting of fly ash, blast furnace slag, silica fume, and recycled materials.

6. The ceramic building material according to claim 1 or 2, further comprising silica sand.

7. The ceramic building material according to claim 1 or 2, wherein the aggregate is at least one of a lightweight aggregate and silica stone.

8. A method for producing the ceramic building material according to claim 1 or 2, A preparation step of preparing a composition comprising magnesium oxide, aggregate, and pulp; a slurry production step of adding water to the composition and kneading the composition to produce a raw material slurry; a forming step of forming the raw material slurry; and a curing step of curing the shaped raw material slurry.

9. The method for producing a ceramic building material according to claim 8 , wherein the curing step cures the raw material slurry at room temperature and normal pressure.

10. The curing step is a step of curing the raw material slurry by CO ２ The method for producing a ceramic building material according to claim 8, wherein the curing is carried out in an atmosphere having a concentration of 5 volume % or more.

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