Binder for rock wool composition, rock wool composition, and method for recycling construction waste

Abstract

To provide a technology for reusing construction waste, more specifically, construction waste mainly composed of CaO and SiO2. More specifically, to provide a technology for cyclically reusing construction waste, which is construction waste mainly composed of CaO and SiO2, and a recycling technology that enables continuous cyclical reuse. To provide a binder for rock wool compositions, a rock wool composition, and a method for recycling construction waste that enables continuous cyclical reuse of construction waste. [Means] As a result of diligent research to solve the above problem, the present inventors have found that construction waste, which is construction material waste mainly composed of CaO and SiO2, is made into a powder, and this powder, cement, and water are used as a binder for a rock wool composition.

Description

Technical Field

[0001] The present invention relates to a binder for rock wool compositions. Specifically, the present invention relates to a binder for rock wool compositions using construction waste materials. The present invention also relates to a rock wool composition. Specifically, the present invention relates to a rock wool composition using construction waste materials. The present invention further relates to a method for recycling construction waste materials. Specifically, the present invention relates to a method for recycling construction waste materials that enables the construction waste materials to be recycled into resources, and further allows repeated recycling of the resources.

Background Art

[0002] Rock wool compositions such as spray-applied rock wool fireproof coating materials, ALC (autoclaved lightweight aerated concrete), general concrete, and inorganic materials mainly composed of CaO and SiO2 represented by calcium silicate such as calcium silicate boards are widely used in buildings such as office buildings and multi-family residences, as well as civil engineering structures such as viaducts and retaining walls. Buildings and civil engineering structures may become partially or entirely waste due to reconstruction, renewal, demolition, and the like. Recycled aggregates for concrete are manufactured from a part of concrete lumps that are concrete waste. To manufacture recycled aggregates for concrete from concrete lumps, the concrete lumps are primarily crushed by a crusher such as a jaw crusher or an impact crusher, and the primary crushed material is used as it is or heated to weaken cement hydrates, then the coarse aggregate inside the primary crushed material is separated from the mortar component (cement hydrates (including unhydrated cement, the same applies hereinafter) and fine aggregate portion) and / or the aggregate (coarse aggregate, fine aggregate) is separated from the cement hydrates using a crusher such as a ball mill or a rod mill, followed by classification with a sieve or the like. In this process, fine powder mainly composed of cement hydrates and crushed aggregate, which is called filler, is generated in an amount of about 30 to 75 mass% relative to the input amount of concrete lumps into the crusher. The more high-quality recycled aggregate for concrete is intended to be produced, the higher the generation ratio of the filler. Most of the filler is disposed of as industrial waste, and as methods for effectively utilizing this filler, methods of using it as a raw material during cement clinker production, methods of using it as a cement admixture (cement blending material), and the like have been proposed (see, for example, Patent Document 1 and Non-Patent Document 1).

[0003] When using fillers generated during the production of recycled aggregate for concrete as raw materials in the production of cement clinker, the amount is limited to about 1% by mass of the raw materials. Even when used as a cement admixture, it reduces the strength and fluidity (or consistency) of the concrete to which it is mixed, thus degrading the performance of the concrete, making it a technology that is difficult to widely use in practice. Furthermore, much of the filler is disposed of as industrial waste, incurring disposal costs, which hinders the widespread adoption of the production of recycled aggregate from concrete blocks.

[0004] Furthermore, it is common practice to provide a fibrous layer made of rock wool composition, consisting of rock wool and a binder such as cement, on the surface of structures for the purpose of imparting fire resistance, fire prevention, sound absorption, and / or heat insulation. Rock wool is a material (mineral fiber) that is rapidly cooled and fibroused from materials mainly consisting of molten rock or blast furnace slag in a melting furnace. During the fibrousization process, some of the material becomes insufficiently fibrous (including material that is partially or entirely granular, powdery, or broken into short fibers; the same applies hereinafter) and cannot be used as a product. Also, when the raw materials are melted, some of the raw materials are discharged as dust along with the exhaust gas and collected by dust collectors. Some of the waste materials generated during rock wool production are used as raw materials in cement production, but the rest are disposed of as industrial waste. In addition, when forming the fibrous layer made of rock wool composition, it is often formed by spraying, and during this process, the material does not adhere to the surface of the structure but falls to the surrounding area and is disposed of as industrial waste. Furthermore, when dismantling structures that have a fibrous layer made of rock wool composition on their surface, the rock wool composition is peeled off the surface of the structure and disposed of as industrial waste.

[0005] A technique has been disclosed for reusing briquettes, which are formed by adding clay minerals and hydraulic inorganic binders to rock wool waste, as part of the raw materials for rock wool (see, for example, Patent Document 2). Furthermore, a technique has been disclosed for recovering material (waste cotton) that does not adhere to the surface of a structure and falls to the surrounding area when forming a fibrous layer made of rock wool composition, and using it again to form a fibrous layer made of rock wool composition (see, for example, Patent Document 3). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-017227 [Patent Document 2] Japanese Patent Application Publication No. 01-192743 [Patent Document 3] Japanese Patent Publication No. 2005-139798 [Non-patent literature]

[0007] [Non-Patent Document 1] "Report on the Survey and Study of Recycling of Construction Waste in Fiscal Year 2022" [online], Ministry of the Environment, [Accessed March 29, 2025], Internet <URL: https: / / www.env.go.jp / content / 000143784.pdf> [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention aims to provide a technology for reusing construction waste, more specifically, construction waste mainly composed of CaO and SiO2. More specifically, the invention aims to provide a technology for cyclically reusing construction waste, which is construction waste mainly composed of CaO and SiO2, and a recycling technology that can continue to be cyclically reused. The invention also aims to provide a binder for rock wool compositions, a rock wool composition, and a method for recycling construction waste that can continue to cyclically reuse the aforementioned construction waste. [Means for solving the problem]

[0009] The inventors of the present invention, after diligently studying to solve the above problems, discovered that the above problems can be solved by powdering construction waste, which is construction waste mainly composed of CaO and SiO2, and by making a binder slurry mainly composed of this powder, cement, and water, and thus completed the present invention. That is, the present invention is a binder for rock wool composition represented by (1), a rock wool composition represented by (2), and a method for recycling construction waste represented by (3). (1) A binder for rock wool compositions comprising a powder of construction waste mainly composed of CaO and SiO2, cement, and water. (2) A rock wool composition comprising the binder for the rock wool composition described in (1) above and rock wool as the main components. (3) A method for recycling construction waste, characterized by combining a binder for rock wool compositions, which is a mixture of construction waste powder mainly composed of CaO and SiO2 and water, with rock wool to form a rock wool composition. [Effects of the Invention]

[0010] According to the present invention, a technology for reusing construction waste mainly composed of CaO and SiO2 is available, and construction waste mainly composed of CaO and SiO2 can be reused as a binder for rock wool compositions. According to the present invention, construction waste mainly composed of CaO and SiO2 can be reused as a rock wool composition. Furthermore, according to the present invention, a method for recycling construction waste mainly composed of CaO and SiO2 is available. According to the present invention, construction waste mainly composed of CaO and SiO2 can be reused as a binder for rock wool compositions, and further combined with rock wool to form a rock wool composition. This rock wool composition contains 50% by mass or more of CaO and SiO2 and is a construction material mainly composed of CaO and SiO2. When it is disposed of, it can similarly be reused as a binder for rock wool compositions and as a rock wool composition, thus enabling a technology for cyclically reusing construction waste, which is construction waste mainly composed of CaO and SiO2, and allowing for continuous cyclical reuse. [Modes for carrying out the invention]

[0011] The binder for rock wool compositions of the present invention is characterized by comprising a powder of construction waste mainly composed of CaO and SiO2, cement, and water as its main components.

[0012] In the present invention, the construction waste materials mainly composed of CaO and SiO2 may be any construction waste materials mainly composed of CaO and SiO2. For example, preferred examples include rock wool compositions such as sprayed rock wool fireproofing materials, ALC (autoclaved lightweight concrete), general concrete, cement mortar, and calcium silicate waste materials represented by calcium silicate boards. Here, the waste materials include waste materials generated during and after construction using the materials, as well as waste materials generated during the manufacture of the materials. Concrete waste materials preferably include fillers generated in the manufacture of recycled aggregates for concrete. In the present invention, the construction waste materials mainly composed of CaO and SiO2 preferably have a total CaO content and SiO2 content (CaO + SiO2) of 50% by mass or more. The cement clinker pulverized material, which is the main component of cement such as Portland cement and blended cement that are used as binders in ALC, general concrete, and cement mortar, mainly contains calcium silicate, specifically alite (3CaO·SiO2) and belite (2CaO·SiO2), and therefore CaO and SiO2 are the main components.

[0013] In this invention, rock wool refers to a material (mineral fiber) that is rapidly cooled and fibroused from materials mainly consisting of rocks or blast furnace slag melted in a melting furnace. For example, slag wool manufactured from materials mainly consisting of blast furnace slag is also included. In addition, suitable examples of rock wool waste materials in this invention include dust that includes some of the raw materials discharged from the melting furnace during rock wool production and collected by a dust collector, material that is partially fibroused during the fibrousing process, material that falls to the surroundings without adhering to the surface of a structure when forming a fibrous layer made of rock wool composition (fallen cotton), and rock wool composition that is separated from the surface of a structure when a structure equipped with a fibrous layer made of rock wool composition is dismantled.

[0014] In this invention, a powder of "construction waste mainly composed of CaO and SiO2" (hereinafter sometimes referred to as "CaO·SiO2 construction waste") is used. If the CaO·SiO2 construction waste is in powder form, it can be used as is. If the CaO·SiO2 construction waste is not in powder form, or if the degree of fineness (particle size) needs to be changed, the degree of fineness (particle size) can be adjusted by crushing it using a crushing device, classifying it using a classifying device, and / or mixing CaO·SiO2 construction waste of different degrees of fineness (particle size) that have been adjusted by crushing or classifying using a mixing device. Suitable crushing devices used here include, for example, jaw crushers, ball mills, rod mills, roller mills, cutter mills, jet mills, pot mills, pin mills, and hammer mills. Suitable classification devices include sieves such as vibrating screens and rotary screens, and airflow classifiers such as cyclones and stationary band separators. Suitable mixing devices include jet mixers, Henschel mixers, ribbon mixers, and V-type mixers. Furthermore, regarding the particle size of the CaO·SiO2 construction waste powder, it is preferable that the mass ratio of the sieve residue (cumulative sieve residue mass ratio, residue rate) with a sieve nominal size of 1.2 mm (nominal mesh opening of 1.18 mm) is 8% or less, as this indicates high strength in the rock wool composition, and more preferably 1% or less.

[0015] The cement used in this invention may be any hydraulic cement, such as ordinary, rapid-hardening, ultra-rapid-hardening, low-heat, and moderate-heat Portland cements, white cement, eco-cement, and various mixed cements obtained by mixing these Portland cements, white cements, or eco-cement with fly ash, blast furnace slag, silica fume, or limestone powder, and two or more of these may be used in combination.

[0016] In the binder for rock wool composition of the present invention, one or more admixtures for cement can be used within a range that does not substantially impair the effects of the present invention. Examples of such admixtures include cement dispersants, expansive materials, waterproof materials, polymers for cement, rust inhibitors, shrinkage reducing agents, pigments, fibers, water repellents, efflorescence preventing agents, quick-setting agents (materials), quick-hardening agents (materials), setting retarders, thickeners, foaming agents, defoamers, gypsum, fine blast furnace slag powder, pozzolanic substances, surface hardening agents, and the like.

[0017] If cement is not contained in the present invention, the strength will be too low to maintain the shape when combined with rock wool to form a rock wool composition. The mass ratio (P / (C+P)) of the "powder of construction waste material mainly composed of CaO and SiO₂" to the total (C+P) of the mass of cement (C) and the mass of the "powder of construction waste material mainly composed of CaO and SiO₂" (P) is preferably 95 mass% or less, more preferably 90 mass% or less, and most preferably 85 mass% or less. In addition, since the reusable amount of construction waste material can be increased, P / (C+P) is preferably 5 mass% or more, more preferably 10 mass% or more, and most preferably 25 mass% or more.

[0018] The rock wool composition of the present invention mainly comprises the aforementioned binder for rock wool composition and rock wool. Here, the rock wool refers to the rock wool described above. The ratio of the mass of rock wool (RW) to the total (RW+C+P) of the mass of rock wool (RW), the mass of cement (C), and the mass of the "powder of construction waste material mainly composed of CaO and SiO₂" (P) contained in the rock wool composition of the present invention (RW / (RW+C+P)) is preferably 5 to 97 mass%, more preferably 10 to 95 mass%, and most preferably 25 to 95 mass%, in view of high strength and excellent thermal performances such as heat insulation performance and fire resistance performance.

[0019] In the rock wool composition of the present invention, one or more admixtures for cement can be used within a range that does not substantially impair the effects of the present invention. Examples of such admixtures include cement dispersants, expansive materials, waterproof materials, polymers for cement, rust preventives, shrinkage-reducing agents, pigments, fibers, water repellents, efflorescence preventives, quick-setting agents (materials), quick-hardening agents (materials), setting retarders, thickeners, foaming agents, defoamers, gypsum, fine blast furnace slag powder, pozzolanic substances, surface hardening agents, and the like.

[0020] The method for recycling construction waste materials according to the present invention is characterized in that a binder for rock wool composition obtained by mixing powder of construction waste materials mainly composed of CaO and SiO₂ with water is combined with rock wool to form a rock wool composition. The binder for rock wool composition is the aforementioned binder for rock wool composition, and the rock wool is also the aforementioned rock wool. [Examples]

[0021] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples at all.

[0022] [Example 1] Powder of CaO·SiO₂ construction waste material shown below was produced. ·Construction waste material powder 1: Fibrous waste material generated during rock wool production was pulverized by a ball mill, and the mass ratio of the residue on a sieve with a nominal sieve size of 1.2 mm is 1% or less. ·Construction waste material powder 2: A fire-resistant coating layer made of a rock wool composition was pulverized by a ball mill, and the mass ratio of the residue on a sieve with a nominal sieve size of 1.2 mm is 1% or less.

[0023] A binder for rock wool compositions was prepared by mixing the prepared CaO·SiO2 construction waste powder, cement, and water in the proportions shown in Table 1. A rock wool composition was then prepared by mixing these materials with rock wool in the same proportions as shown in Table 1. The prepared rock wool compositions were then filled into molds to create 30 mm cube specimens. The preparation of the binder and rock wool compositions was carried out in a constant temperature room at 20°C. The specimens, cured in the constant temperature room at 20°C, were demolded after 1 day, and their oven-dry bulk density was measured and evaluated. Strength and circulation efficiency were also evaluated. The results of each evaluation are shown in Table 1. The cement used was ordinary Portland cement manufactured by Taiheiyo Cement Corporation, the rock wool was granular rock wool cotton manufactured by Taiheiyo Material Co., Ltd., and the water used was tap water from Sakura City. The "total CaO content and SiO2 content (CaO+SiO2)" of the CaO·SiO2 construction waste powder is also shown in accordance with Table 1. • Dry bulk density The specimens were dried in a drying oven at 105°C until a constant weight was reached. The volume (V) of the specimens was determined from the external dimensions after drying, and the oven-dry bulk density (ρ) was calculated from this value and the mass (M) of the specimens at that time using the following equation (1). The oven-dry bulk density (ρ) was 1.0 g / cm³. 3 The following conditions are considered "Good" (indicated as ○): 1.0 g / cm³ 3 If the value exceeded this, it was evaluated as "poor" (indicated as ×). Absolute dry bulk density (ρ) of 1.0 g / cm³ 3 The following conditions are preferable because they impart properties such as fire resistance, heat insulation, and sound absorption to the rock wool composition. ρ = M / V ····· (1) ·Strength During demolding, the specimen was evaluated as "good" (indicated as ○) if it could be picked up with fingers without collapsing and its shape was maintained, and as "poor" (indicated as ×) if it collapsed. • Circulation efficiency The proportion of CaO·SiO2 construction waste powder used was evaluated as "good" (indicated as ○) if it was 1% by mass or more of the rock wool composition, and as "poor" (indicated as ×) if it was less than 1% by mass.

[0024] [Table 1]

[0025] The rock wool composition using the binder for rock wool compositions at the test level corresponding to the embodiment of the present invention exhibited excellent strength at 1 day of age, maintaining its shape without crumbling when picked up by fingers. Furthermore, it also showed excellent evaluation of circulation efficiency and absolute dry bulk density.

[0026] [Example 2] The rock wool composition prepared at test level 5 was ground using a ball mill to obtain the resulting powder, which was designated as construction waste powder 3. The "mass ratio of sieve residue on a sieve with a nominal sieve size of 1.2 mm" of this construction waste powder 3 was 1% or less. Using this construction waste powder 3, a binder for rock wool compositions and rock wool compositions were prepared in the same manner as at test level 5, and tested and evaluated, as shown in Table 2.

[0027] [Table 2]

[0028] Based on the results of test level 22, a rock wool composition was prepared using a binder for rock wool compositions. The rock wool composition using the binder exhibited excellent strength at 1 day of age, maintaining its shape without crumbling when picked up with fingers. Furthermore, the evaluation of recycling efficiency and absolute dry bulk density was also excellent. This indicates that the binder for rock wool compositions, the rock wool composition, and the recycling method for construction waste can be continuously reused in a cyclical manner.

[0029] [Example 3] To simulate the fillers generated during the production of recycled aggregate for concrete, a mortar was prepared using cement, silica sand, and water in a mass ratio of 20 parts cement, 80 parts silica sand, and 11 parts water per 100 parts total mass of cement and silica sand. The hardened mortar was powdered using a disc mill after 28 days to obtain construction waste powder 4. The "mass ratio of sieve residue with a nominal sieve size of 1.2 mm" of this construction waste powder 4 was 1% or less. Using construction waste powder 4, a binder for rock wool compositions and rock wool compositions were prepared and tested and evaluated in the same manner as in test level 5, and the results are shown in Table 3.

[0030] [Table 3]

[0031] The results from test level 23 showed that the rock wool composition using the prepared binder exhibited excellent strength at 1 day of age, maintaining its shape without crumbling when picked up with fingers. Furthermore, the evaluation of recycling efficiency and oven-dry bulk density was also excellent. This indicates that a binder for rock wool compositions, a rock wool composition, and a recycling method for construction waste can be obtained that allows for continuous cyclical reuse even when using fillers generated in the production of recycled aggregate for concrete, as construction waste powder mainly composed of CaO and SiO2. [Industrial applicability]

[0032] This invention is a technology for the cyclical reuse of construction waste materials mainly composed of CaO and SiO2. According to this invention, since construction waste materials can be reused, it can contribute to extending the lifespan of final disposal sites for industrial waste.

Claims

1. CaO and SiO ２ A binder for rock wool compositions, mainly composed of construction waste powder, cement, and water.

2. A rock wool composition comprising the binder for rock wool composition described in claim 1 and rock wool as its main components.

3. CaO and SiO ２ A method for recycling construction waste, characterized by combining a binder for rock wool compositions, which is a mixture of construction waste powder mainly composed of and water, with rock wool to form a rock wool composition.

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