Lightweight aggregate, method for producing same, and mortar and concrete using same

Abstract

The lightweight aggregate according to one embodiment of the present disclosure is a granular body in which protrusions having an average diameter of less than 3.0 mm are dispersed on the surface, the arithmetic average roughness Ra of the surface excluding the protrusions is in the range of 10-100 [mu] m, and the density is in the range of 0.9-1.3 g / cm3.

Description

Technical Field

[0001] This disclosure relates to lightweight aggregates and methods for manufacturing them, as well as mortars and concretes using the lightweight aggregates. Background Technology

[0002] Lightweight aggregates containing plastic waste are being researched as aggregates for mortar and concrete. For example, the use of composites containing plastic waste and waste other than plastic waste as lightweight aggregates is being investigated (see, for example, Patent Document 1 and Patent Document 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 11-147739

[0006] Patent Document 2: Japanese Patent Application Publication No. 2006-169066 Summary of the Invention

[0007] From the perspective of efficient resource utilization, lightweight aggregates made from plastic waste are preferred. However, generally speaking, the resins contained in plastic waste have low affinity for cement and water. Therefore, lightweight aggregates containing resin are difficult to disperse evenly in mortar and concrete, and mortar and concrete containing such lightweight aggregates tend to have reduced mechanical strength and durability. In addition, plastic waste sometimes contains aluminum vapor-deposited coatings. If plastic waste containing aluminum vapor-deposited coatings is used as lightweight aggregates in mortar and concrete, the aluminum in the aluminum vapor-deposited coating sometimes reacts with the alkali from cement to produce hydrogen, causing the mortar and concrete to expand due to this hydrogen.

[0008] The purpose of this disclosure is to provide a lightweight aggregate that, although containing resin, particularly plastic waste, has high affinity for cement and water and is easily and uniformly dispersed in mortar and concrete, as well as a method for manufacturing the same, and mortar and concrete using the lightweight aggregate.

[0009] This disclosure relates to a lightweight bone material, which is a granular body with protrusions having an average diameter of less than 3.0 mm dispersed on its surface, and an arithmetic mean roughness Ra of the surface excluding the protrusions in the range of 10 μm to 100 μm, and a density of 0.9 g / cm³. 3 ~1.3g / cm 3 Within the range. Attached Figure Description

[0010] Figure 1 This is a cross-sectional view showing a lightweight bone material according to one embodiment of the present disclosure.

[0011] Figure 2 This is a surface image of the lightweight fine aggregate obtained in this embodiment.

[0012] Figure 3 This is a surface image of the lightweight coarse aggregate obtained in this embodiment. Detailed Implementation

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0014] [Lightweight bone material]

[0015] Figure 1 This is a cross-sectional view showing a lightweight bone material according to one embodiment of the present disclosure.

[0016] like Figure 1 As shown, the lightweight bone material 1 is a granular body having granular portions 10 and protrusions 20 dispersed on the surface of the granular portions 10. The protrusions 20, for example, have a diameter (…). Figure 1 The value of D in the figure is 0.05 mm or more and the height is ( Figure 1 The height H of the protrusion 20 is 0.2 mm or more. The height H of the protrusion 20 is the length relative to the surface 10a of the granular portion 10. The shape of the granular portion 10 is not particularly limited, and can be, for example, spherical, elliptical, cylindrical, prismatic, conical, pyramidal, or irregular.

[0017] In the lightweight bone material 1, the arithmetic mean roughness Ra of the surface 10a of the granular portion 10 (excluding the protrusions 20) is in the range of 10 μm to 100 μm. The maximum height roughness Rz of the surface 10a of the granular portion 10 (excluding the protrusions 20) can, for example, be in the range of 3 to 6 times the arithmetic mean roughness Ra. The arithmetic mean roughness Ra can, for example, be in the range of 20 μm to 70 μm. The maximum height roughness Rz can, for example, be in the range of 60 μm to 400 μm, or in the range of 60 μm to 180 μm. The arithmetic mean roughness Ra and the maximum height roughness Rz are, for example, the average of the arithmetic mean roughness Ra and the maximum height roughness Rz measured at three locations on the surface 10a of the granular portion 10 of 10 lightweight bone materials 1 as test samples. The arithmetic mean roughness Ra and the maximum height roughness Rz can be measured, for example, using a shape-measuring laser microscope.

[0018] The average diameter D of the protrusions 20 of the lightweight bone material 1 is less than 3.0 mm. The average diameter of the protrusions 20 can, for example, be in the range of 0.1 mm or more and less than 2.0 mm. The average height H of the protrusions 20 of the lightweight bone material 1 can, for example, be in the range of 0.4 mm to 2.0 mm. The average diameter and average height of the protrusions 20 are, for example, the average of the diameter and height of the protrusions 20 measured on 10 lightweight bone materials 1 as test specimens. The diameter and height of the protrusions 20 can be measured, for example, using a shape-measuring laser microscope.

[0019] There is no particular limitation on the number of protrusions 20 of the lightweight bone material 1, but the average number of protrusions 20 of each lightweight bone material 1 can be in the range of 5 to 100, or in the range of 10 to 50.

[0020] The density of lightweight bone material 1 is 0.9 g / cm³. 3 ~1.3g / cm 3 The water absorption rate of lightweight aggregate 1 can be, for example, in the range of 5% by mass to 20% by mass. The density and water absorption rate of lightweight aggregate 1 are, for example, values ​​determined according to JIS A 1109:2020 (Test Method for Density and Water Absorption of Fine Aggregates) or JIS A 1110:2020 (Test Method for Density and Water Absorption of Coarse Aggregates). The volumetric mass per unit area (ocean-dry state) of lightweight aggregate 1 can be in the range of 0.2 kg / L to 0.8 kg / L. The volumetric mass per unit area is, for example, a value determined according to JIS A 1104:2019 (Test Method for Volumetric Mass and Volumetric Ratio of Aggregates).

[0021] The particle size of lightweight aggregate 1 is not particularly limited and can be adjusted according to the application. For example, when used as fine aggregate, the residue on a 2.5mm sieve (measuring using a 2.5mm mesh) can be 95% by mass or more, and the residue on a 5.0mm sieve (measuring using a 5.0mm mesh) can be less than 15% by mass. When used as coarse aggregate, the residue on a 5.0mm sieve (measuring using a 5.0mm mesh) can be 85% by mass or more. When used as [specific application], the residue on a 25mm sieve (measuring using a 25mm mesh) can be less than 5% by mass.

[0022] The lightweight aggregate 1 comprises a low-melting-point resin 11, non-low-melting-point resin particles 12 dispersed in the low-melting-point resin, and wood particles 13. The low-melting-point resin 11 is bonded to the non-low-melting-point resin particles 12 and wood particles 13 to form a granular portion 10. A portion of the non-low-melting-point resin particles 12 and wood particles 13 protrudes from the surface 10a of the granular portion 10, forming protrusions 20. The low-melting-point resin 11 forms the unevenness of the surface 10a of the granular portion 10.

[0023] Low-melting-point resin 11 is, for example, a thermoplastic resin with a melting point in the range of 80°C or higher and less than 190°C. Examples of low-melting-point resin 11 include polystyrene (PS), acrylonitrile-butadiene-styrene resin (ABS), polyethylene (PE), polymethyl methacrylate (PMMA), polycarbonate (PC), polypropylene (PP), polyamide 12 (PA12), and polyacetal (POM). Non-low-melting-point resin particles 12 include, for example, at least one of high-melting-point resins with a melting point of 190°C or higher and thermosetting resins. The melting point of high-melting-point resins can be 340°C or lower. Examples of high-melting-point resins include polyethylene terephthalate (PET), polyamide 6 (PA6), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyetheretherketone (PEEK). Thermosetting resin is a cured resin. Examples of thermosetting resins include polyimide (PI), polyurethane (PU), and phenolic resin (PF). The average major diameter of the non-low melting point resin particles 12 can be, for example, less than 3.0 mm, or in the range of more than 0.5 mm and less than 2.0 mm.

[0024] The low-melting-point resin 11 and the non-low-melting-point resin particles 12 can be derived from plastic waste.

[0025] The average major diameter of the wood particles 13 can be less than 3.0 mm, or it can be in the range of 0.5 mm or more but less than 2.0 mm. The wood particles 13 can be, for example, shredded waste wood. As waste wood, for example, construction waste, thinnings, and sawdust can be used.

[0026] The content of low-melting-point resin 11 in lightweight aggregate 1 can, for example, range from 10% to 80% by mass, or from 10% to 50% by mass. The content of non-low-melting-point resin particles 12 in lightweight aggregate 1 can, for example, range from 10% to 80% by mass, or from 15% to 75% by mass. The content of wood particles 13 in lightweight aggregate 1 can, for example, range from 10% to 50% by mass, or from 20% to 40% by mass. The ratio of the total content of low-melting-point resin 11 and non-low-melting-point resin particles 12 to the content of wood particles 13 (total content of low-melting-point resin 11 and non-low-melting-point resin particles 12 / content of wood particles 13), by mass, can, for example, be 3.0 or less, or 2.5 or less.

[0027] The lightweight aggregate 1 may further include pigments, compatibilizers for improving the affinity between low-melting-point resin 11 and non-low-melting-point resin particles 12 and wood particles 13, fillers, lubricants, weathering agents, heat stabilizers, foaming agents, antistatic agents and other additives.

[0028] The lightweight aggregate 1 of this embodiment, as described above, is distributed with protrusions 20 of average diameter within the aforementioned range. The arithmetic mean roughness Ra and density of the surface 10a of the granular portions 10 (excluding the protrusions 20) are within the aforementioned range. Therefore, the lightweight aggregate 1 is less prone to agglomeration and has a larger contact area with cement and water. Thus, even if the lightweight aggregate 1 of this embodiment contains resin, it can be uniformly dispersed in mortar and concrete, and the increased contact area between the lightweight aggregate 1 and cement improves the mechanical strength of the mortar and concrete using this lightweight aggregate. Furthermore, its density is within the aforementioned range, making it lower than that of sand and gravel used as aggregates in mortar and concrete. Therefore, the lightweight aggregate 1 of this embodiment can be advantageously used as aggregate in mortar and concrete.

[0029] In this embodiment, the lightweight aggregate 1 comprises non-low-melting-point resin particles 12 and wood particles 13 dispersed in a low-melting-point resin 11. The melting point of the low-melting-point resin 11 is within the aforementioned range, and the non-low-melting-point resin particles 12 comprise at least one of the aforementioned high-melting-point resin and thermosetting resin. The granular portion 10 is formed from the low-melting-point resin 11, and the protrusions 20 are formed from at least one of the non-low-melting-point resin particles 12 and wood particles 13. In this case, the density is low, allowing for more reliable and uniform dispersion in mortar and concrete. In particular, the wood particles 13 have a high affinity for water, thus the lightweight aggregate 1 containing wood particles 13 is more easily and uniformly dispersed in mortar and concrete. Furthermore, the wood particles 13 have a high affinity for cement, so even if the mortar or concrete using the lightweight aggregate 1 containing wood particles 13 is damaged, cracks and fissures are less likely to propagate. Moreover, when the low-melting-point resin 11 and the non-low-melting-point resin particles 12 are derived from plastic waste, resources can be effectively utilized. Plastic waste sometimes contains aluminum vapor-deposited films. Aluminum vapor-deposited films are generally formed by depositing aluminum onto a low-melting-point resin film. Therefore, in the lightweight aggregate 1 of this embodiment, the aluminum in the aluminum vapor-deposited film is dispersed in the granular portion 10 in an oxidized state along with the low-melting-point resin 11. Therefore, the lightweight aggregate 1 of this embodiment is less likely to generate hydrogen even when used as a lightweight aggregate in mortar or concrete.

[0030] In the lightweight aggregate 1 of this embodiment, when the average number of protrusions 20 in each lightweight aggregate 1 is within the above-mentioned range, the lightweight aggregate 1 is less likely to agglomerate and is more likely to be evenly dispersed in mortar and concrete. In addition, when the height of the protrusions 20 is within the above-mentioned range, the lightweight aggregate 1 is even less likely to agglomerate and is even more likely to be evenly dispersed in mortar and concrete.

[0031] In this embodiment, lightweight aggregate 1, which has a sieve residue of 95% or more when measured using a sieve with a mesh size of 2.5 mm and a sieve residue of less than 15% by mass when measured using a sieve with a mesh size of 5.0 mm, can be used as fine aggregate in mortar and concrete. Furthermore, lightweight aggregate 1, which has a sieve residue of 85% or more when measured using a sieve with a mesh size of 5.0 mm, can be used as coarse aggregate in concrete.

[0032] [Method for manufacturing lightweight aggregates]

[0033] The lightweight aggregate 1 of this embodiment can be manufactured, for example, by a method including a molding process, a crushing process, and a grading process. The molding process involves extruding a mixture comprising low-melting-point resin 11, non-low-melting-point resin particles 12, and wood particles 13 to form a molded body. The crushing process crushes the obtained molded body to obtain pulverized material. The grading process grades the obtained pulverized material. Hereinafter, the manufacturing method of the lightweight aggregate will be described using examples of using plastic waste as the material for both low-melting-point and non-low-melting-point resin particles and waste wood as the material for wood particles.

[0034] Plastic waste can be derived from general waste, industrial waste, and marine plastic waste. General waste includes all waste other than industrial waste and marine plastic waste, including household waste. Plastic waste can contain substances other than synthetic resins. Substances other than synthetic resins can be inorganic or organic. Inorganic substances include, for example, magnetic materials, non-magnetic metals, glass, pebbles, metals, shells, sand, silica gel and other drying materials, and iron-based deoxidizers. Examples of magnetic materials include iron, stainless steel, ferrites, cobalt, and nickel. Examples of non-magnetic metals include aluminum, copper, zinc, and brass. Organic substances include, for example, grease, food scraps, and surfactants.

[0035] Examples of plastic waste from general waste include plastics used as containers and packaging materials for goods. Plastic waste from industrial waste is plastic waste generated alongside commercial activities. Examples of industrial plastic waste include off-the-shelf products and surplus manufactured goods. Plastic waste from the ocean is plastic waste accumulated in the ocean through direct dumping of plastic into the sea or through rivers and lakes from land-based waste. Examples of marine plastic waste include plastics discarded in the ocean (plastic sheets, plastic bottles, fishing gear) and plastic products that have deteriorated into microplastics smaller than 5 mm due to the effects of waves and ultraviolet radiation.

[0036] The content of low-melting-point resin in the synthetic resin contained in plastic waste can, for example, range from 25% to 95% by mass, or from 35% to 90% by mass. The combined content of PP and PE in the low-melting-point resin of the plastic waste can be less than 90% by mass, or from 20% to 80% by mass. The content of non-low-melting-point resin in the synthetic resin contained in plastic waste can, for example, range from 5% to 75% by mass, or from 10% to 65% by mass. Furthermore, the ratio of low-melting-point resin to the content of non-low-melting-point resin contained in the low-melting-point resin (low-melting-point resin / non-low-melting-point resin), for example, by mass ratio, can range from 1 / 3 to 5.00, or from 0.71 to 3.00. In addition, the ratio of thermosetting resin to high-melting-point resin in non-low-melting-point resins of plastic waste (thermosetting resin / high-melting-point resin) can be in the range of 0.01 to 100 or 0.05 to 50 by mass, for example.

[0037] Methods for recovering low-melting-point and non-low-melting-point resin particles from plastic waste may include, for example, a crushing process, a magnetic material removal process, a non-magnetic metal removal process, a washing process, a volume reduction process, and a pulverizing process. The crushing process involves using a crusher to break down plastic waste into plastic flakes. For example, a single-shaft crusher can be used as the crusher. The magnetic material removal process involves using a magnetic separator to remove magnetic materials contained in the recycled plastic flakes. For example, a suspended magnetic separator, a wheeled magnetic separator, a drum magnetic separator, or a roller magnetic separator can be used. The non-magnetic metal removal process involves using a non-magnetic metal separator to remove non-magnetic metals contained in the recycled plastic flakes. For non-magnetic metal separators, an eddy current separator can be used. The washing process involves using a wet pulverizing and washing machine with a pulverizing function to pulverize the plastic flakes into coarse plastic particles, while simultaneously washing away any adhering substances attached to the coarse plastic particles. The adhering substances include organic matter such as grease, food residue, and surfactants, as well as inorganic matter such as glass, small stones, metal, shells, sand, drying materials, and deoxidizers. The volume reduction process involves removing moisture adhering to the coarse plastic particles using a pressing volume reduction machine, thereby reducing the volume of the coarse plastic particles. A screw-type pressing volume reduction machine with a screw inside a barrel having drainage holes can be used. The pulverizing process involves pulverizing the coarse plastic particles using a pulverizer to obtain resin composition particles. A micro-pulverizer (shredder) with fixed blades and rotating blades, where plastic sheets are clamped between the fixed and rotating blades for pulverization, can be used. The coarse plastic particles are pulverized until they pass through a sieve with a specified mesh size. For example, the mesh size of the sieve can be 3.0 mm. In this way, resin composition particles containing low-melting-point resin particles and non-low-melting-point resin particles with a specified average major diameter can be obtained.

[0038] As a method for recovering wood particles from waste wood, a process including a crushing step, a magnetic material removal process, and a pulverizing step can be used. The crushing step involves using a crusher to break down waste wood into wood chips. For example, a single-shaft crusher can be used as the crusher. The magnetic material removal process involves using a magnetic separator to remove magnetic materials contained in the recovered wood chips. The aforementioned magnetic separator can be used as the magnetic separator. The pulverizing step involves using a pulverizer to pulverize the wood chips into wood particles. A shredder can be used as the pulverizer. Pulverizing can be performed simultaneously with the pulverizing of coarse plastic particles, using the same apparatus as described above.

[0039] In the molding process, the resin composition particles obtained as described above and wood particles are mixed in the above proportions to obtain a mixture. Next, the resulting mixture is extruded to form a molded body. Through extrusion molding, the low-melting-point resin particles melt, resulting in a molded body in which non-low-melting-point resin particles and wood particles are dispersed within the low-melting-point resin. The shape of the molded body is not particularly limited; for example, it can be plate-shaped. The molding temperature of the molded body is, for example, a temperature above the melting point of the low-melting-point resin particles and below the melting point of the non-low-melting-point resin particles. The molding temperature of the molded body varies depending on factors such as the type and content of the low-melting-point resin contained in the raw material mixture; for example, it is 150°C or higher when PE is included. On the other hand, wood particles decompose and vaporize at temperatures above 190°C, sometimes generating bubbles in the resin composition molded body; therefore, the molding temperature is preferably less than 190°C.

[0040] In the crushing process, the obtained molded body is crushed using a crushing device to obtain crushed material. A single-shaft crusher can be used as the crushing device for the molded body. Crushing is performed until it passes through a sieve with a specified mesh size. The mesh size of the sieve can be, for example, 15.0 mm. The molded body is crushed starting with the wood particles and non-low-melting-point resin particles within it. Therefore, protrusions with wood particles and non-low-melting-point resin particles protruding from the surface are formed. Additionally, unevenness is formed on the surface of the low-melting-point resin between the wood particles and non-low-melting-point resin particles, with an arithmetic mean roughness Ra ranging from 10 μm to 100 μm.

[0041] In the grading process, the resulting pulverized material is graded using a grading device. For example, a vibrating screen can be used as a grading device.

[0042] According to the manufacturing method of the lightweight aggregate 1 of this embodiment with the configuration described above, it is industrially advantageous to manufacture a surface 10a with protrusions 20 of average diameter less than 3.0 mm dispersed on the surface, an arithmetic mean roughness Ra of the granular portion 10 excluding the protrusions 20 being in the range of 10 μm to 100 μm, and a density of 0.9 g / cm³. 3 ~1.3g / cm 3 The lightweight aggregate 1 is within the range of [specific parameters]. Furthermore, in cases where the plastic waste contains an aluminum vapor-deposited film, the aluminum in the aluminum vapor-deposited film is oxidized by heating during the molding process and dispersed in molten low-melting-point resin. Therefore, the lightweight aggregate 1 obtained by the manufacturing method of this embodiment is less prone to hydrogen generation even when used as a lightweight aggregate in mortar or concrete.

[0043] [mortar]

[0044] The mortar of this embodiment comprises cement and the aforementioned lightweight aggregate 1. The content of lightweight aggregate 1 in the mortar is, for example, in the range of 10% to 30% by mass. The mortar of this embodiment can be used, for example, as an exterior wall material, an interior wall material, a base for ceramic tiles, and a jointing material for bricks and blocks.

[0045] The mortar of this embodiment can be manufactured, for example, by mixing cement, lightweight aggregate 1 and water to prepare fresh mortar, applying the obtained fresh mortar and drying it.

[0046] According to the mortar of this embodiment with the configuration described above, since it contains the aforementioned lightweight aggregate 1, the lightweight aggregate 1 is easily and evenly dispersed and easily exhibits strength.

[0047] [Concrete]

[0048] The concrete of this embodiment comprises cement, fine aggregate, and coarse aggregate. At least one of the fine aggregate and coarse aggregate is the aforementioned lightweight aggregate 1. The content of the lightweight aggregate in the concrete is, for example, in the range of 10% to 30% by mass. The concrete of this embodiment can be used, for example, as a material for various civil engineering projects such as foundation engineering, external structure engineering, and paving materials.

[0049] The concrete of this embodiment can be manufactured, for example, by a method including a fresh concrete preparation step, a pouring step, and a demolding step. The fresh concrete preparation step is a step of preparing fresh concrete by mixing cement, fine aggregate, coarse aggregate, and water. The pouring step is a step of pouring the obtained fresh concrete into a concrete molding mold. The demolding step is a step of removing the concrete that has cured from the mold.

[0050] The concrete of this embodiment, constructed as described above, contains the aforementioned lightweight aggregate 1, which is easily and evenly dispersed and readily exhibits strength.

[0051] The embodiments of this disclosure have been described above, but this disclosure is not limited thereto and can be appropriately modified. In the lightweight aggregate 1 of this embodiment, the structure comprises a low-melting-point resin 11 and non-low-melting-point resin particles 12 and wood particles 13 dispersed in the low-melting-point resin 11, but this disclosure is not limited thereto. For example, ceramic particles can be used instead of wood particles 13 or used in conjunction with wood particles 13. Furthermore, in the lightweight aggregate 1 of this embodiment, the low-melting-point resin 11 and non-low-melting-point resin particles 12 are plastic waste, but this disclosure is not limited thereto. For example, resin products can be used as the low-melting-point resin 11 and non-low-melting-point resin particles 12. Additionally, in the manufacturing method of the lightweight aggregate 1 of this embodiment, the low-melting-point resin is pulverized to form particles, but as long as the low-melting-point resin melts during extrusion molding, it does not have to be particles.

[0052] Example

[0053] The present disclosure will now be described in more detail with reference to embodiments. The present disclosure is not limited to these embodiments.

[0054] [Example 1: Production and evaluation of lightweight fine aggregate and lightweight coarse aggregate]

[0055] Plastic waste from general waste, containing both low-melting-point resins (PE, PP, PS) and non-low-melting-point resins (PA6, PET), is fed into a crusher for crushing. The crushed material is then sent to a high-magnetic-force belt-driven magnetic separator with a surface magnetic force of 20,000 Gauss to remove magnetic materials. Next, the crushed material, after removing magnetic materials, is crushed in a single-shaft coarse crusher until it passes through a 50mm mesh sieve to obtain plastic waste flakes. A suspended magnetic separator and a belt-driven magnetic separator are used to remove any magnetic materials from the recycled plastic waste flakes. Next, a non-magnetic metal separator is used to remove non-magnetic metals from the recycled plastic waste flakes. The plastic waste flakes are then simultaneously crushed and washed in a wet crushing and washing machine until they pass through a 12mm mesh sieve to obtain coarse plastic waste particles. Finally, the coarse plastic waste particles washed in the wet crushing and washing machine are pressed and dehydrated using a volume-reducing press to reduce their volume. Then, the reduced-volume coarse plastic waste particles are shredded using a shredder-type crusher until they pass through a 1mm mesh sieve. This yields plastic waste particles. The obtained plastic waste particles contain 49% by mass of low-melting-point resin and 50% by mass of non-low-melting-point resin.

[0056] Waste wood is crushed using a shredder until it passes through a 50mm mesh sieve to obtain waste wood chips. A suspended magnetic separator and a wheeled magnetic separator are then used to remove magnetic materials from the recycled waste wood chips. Next, the waste wood chips are shredded using a shredder-type crusher until they pass through a 1mm mesh sieve. This yields waste wood particles.

[0057] Plastic waste particles, waste wood particles, and additives (including a mixture of pigments, compatibilizers, inorganic fillers, lubricants, and weather-resistant materials) are mixed in a mass ratio of 62:35:3 to obtain a mixture. The resulting mixture is then extruded to obtain a sheet-like molded body. The molded body is then pulverized using a single-shaft crusher until it passes through a 15mm mesh sieve to obtain pulverized material.

[0058] The resulting pulverized material was graded using sieves with mesh sizes of 2.5 mm and 5.0 mm. The pulverized material remaining on the 2.5 mm sieve was used as lightweight fine aggregate, and the pulverized material remaining on the 5.0 mm sieve was used as lightweight coarse aggregate.

[0059] For the obtained lightweight coarse aggregate, sieves with mesh sizes of 2.5 mm, 5.0 mm, 10 mm, 15 mm, 20 mm, and 25 mm were used, and the mass fraction (pass rate) of the pulverized material passing through each sieve was determined according to JIS A 1102:2014 (test method for sieving of aggregates). The results are shown in Table 1 below.

[0060]

[0061] For the obtained lightweight fine aggregate and lightweight coarse aggregate, the surface appearance, surface roughness, density, water absorption rate, and oven-dry volumetric mass were determined by the following methods. The results of the surface roughness, density, water absorption rate, and volumetric mass (oven-dry state) are shown in Table 2 below.

[0062] (Surface observation)

[0063] Surface observation was performed using a digital microscope (Manufactured by Keyence Corporation, VHX-900F). Figure 2 A surface image representing a lightweight, fine aggregate. Figure 3 A surface image representing a lightweight coarse aggregate. (From...) Figure 2 and Figure 3 The observed images confirmed that the lightweight fine aggregate and the lightweight coarse aggregate had non-low melting point resin particles and wood particles exposed on their surfaces, respectively, with some of the wood particles scattered in the form of protrusions.

[0064] (Surface roughness)

[0065] For 10 lightweight fine and lightweight coarse aggregates, three regions without protrusions (size: 500 × 725 μm) were selected. Using a shape measurement laser microscope (Keyence Corporation, VK-X100), the arithmetic mean roughness Ra and the maximum height roughness Rz along a straight line set in each region were measured. The average value of the obtained arithmetic mean roughness Ra and the average value of the maximum height roughness Rz were calculated.

[0066] (Density, water absorption rate)

[0067] The density and water absorption rate of lightweight fine aggregates are determined according to JIS A 1109:2020 (Test method for density and water absorption rate of fine aggregates). The density and water absorption rate of lightweight fine aggregates are determined according to JIS A 1110:2020 (Test method for density and water absorption rate of coarse aggregates).

[0068] (Unit volume mass)

[0069] The determination was made in accordance with JIS A 1104:2019 (Test method for volumetric mass and volume fraction of aggregate).

[0070]

[0071] [Example 2, Comparative Example 1, Reference Example 1: Preparation and Evaluation of Fresh Mortar]

[0072] Prepare the materials shown in Table 3 below. For plastic waste particles, crush the reduced-volume coarse plastic waste particles using a shredder-type shredder until they pass through a 5mm mesh sieve. Otherwise, prepare the materials in the same manner as in Example 1.

[0073]

[0074] Mix the above materials in the proportions shown in Table 4 below using a mortar mixer to prepare fresh mortar.

[0075] Using the obtained fresh mortar, test specimens were prepared according to JIS R 5201:2015 (Physical Test Methods for Cement), and the volumetric mass and flexural strength of the obtained specimens were determined. The volumetric mass of the specimen was calculated by dividing the weight of the specimen by its volume. The volume of the specimen was calculated from the measured dimensions. In addition, the ratio of flexural strength to volumetric mass (flexural strength / volumetric mass) was calculated as the specific strength. The results are shown in Table 4 below.

[0076]

[0077] The specific strength of the test specimen obtained from the fresh mortar of Example 2, which used the lightweight fine aggregate obtained in Example 1, was 1.55, the same as the specific strength of the test specimen obtained from the fresh mortar of Reference Example 1 using conventional sand. This result confirms that the mortar exhibits strength when using the lightweight fine aggregate obtained in Example 1. Furthermore, the test specimen obtained from the fresh mortar of Comparative Example 1, which used plastic waste particles, expanded during curing. This is because the aluminum in the aluminum vapor-deposited film contained in the plastic waste particles reacts with the alkali from the cement to produce hydrogen gas.

[0078] [Examples 3-5, Reference Example 2: Preparation and Evaluation of Fresh Concrete]

[0079] Prepare the materials shown in Table 5 below.

[0080]

[0081] The above materials were mixed using a mortar mixer at the proportions shown in Table 6 below to prepare fresh concrete. It should be noted that in Examples 3-5, the water / cement ratio (W / C ratio) was adjusted so that the slump of the fresh concrete was in the range of 5-15 cm.

[0082] Using the obtained fresh concrete, test specimens were prepared according to JIS A 1106:2018 (test method for flexural strength of concrete), and the volumetric mass and flexural strength of the obtained test specimens were determined. The results are shown in Table 6 below.

[0083]

[0084] It is evident that by using the lightweight coarse aggregate obtained in this embodiment, the volumetric mass of concrete can be significantly reduced. Furthermore, it is evident that by adjusting the proportion of the lightweight coarse aggregate, concrete with the same volumetric mass and flexural strength as the fresh concrete obtained in Reference Example 2 using conventional lightweight fine aggregate and lightweight coarse aggregate can be obtained.

[0085] The following notes are published in the following manner.

[0086] (Note 1)

[0087] A lightweight bone material is a granular body with protrusions of an average diameter of less than 3.0 mm scattered on its surface. The arithmetic mean roughness Ra of the surface, excluding the protrusions, is in the range of 10 μm to 100 μm, and the density is 0.9 g / cm³. 3 ~1.3g / cm 3 Within the range.

[0088] (Note 2)

[0089] According to Appendix 1, the lightweight aggregate comprises a low-melting-point resin and non-low-melting-point resin particles and wood particles dispersed in the low-melting-point resin. The low-melting-point resin has a melting point in the range of 80°C or higher and less than 190°C. The non-low-melting-point resin particles comprise at least one of a high-melting-point resin with a melting point of 190°C or higher and a thermosetting resin. The protrusions are formed by at least one of the non-low-melting-point resin particles and the wood particles.

[0090] (Note 3)

[0091] According to the lightweight bone material described in Appendix 1 or 2, the average number of the aforementioned protrusions in each of the aforementioned lightweight bone materials is in the range of 5 to 100.

[0092] (Note 4)

[0093] The lightweight bone material according to any one of Appendices 1 to 3, wherein the average height of the aforementioned protrusions is in the range of 0.4 mm to 2.0 mm.

[0094] (Note 5)

[0095] According to any one of Appendices 1 to 4, the lightweight bone material has a sieve residue of 95% by mass or more when measured using a sieve with a mesh size of 2.5 mm, and a sieve residue of less than 15% by mass when measured using a sieve with a mesh size of 5.0 mm.

[0096] (Note 6)

[0097] The lightweight bone material according to any one of Appendices 1 to 5, wherein the residue on a sieve measured using a sieve with a mesh size of 5.0 mm is 85% by mass or more.

[0098] (Note 7)

[0099] A lightweight aggregate is a granular body with protrusions having an average diameter of less than 3.0 mm dispersed on its surface. It comprises a low-melting-point resin and non-low-melting-point resin particles and wood particles dispersed in the low-melting-point resin. The melting point of the low-melting-point resin is in the range of 80°C or higher and less than 190°C. The non-low-melting-point resin particles comprise at least one of a high-melting-point resin with a melting point of 190°C or higher and a thermosetting resin. The protrusions are formed by at least one of the non-low-melting-point resin particles and the wood particles.

[0100] (Postscript 8)

[0101] According to the lightweight aggregate described in Appendix 7, the aforementioned low-melting-point resin and the aforementioned non-low-melting-point resin particles are derived from plastic waste.

[0102] (Note 9)

[0103] A method for manufacturing lightweight aggregate involves extruding a mixture comprising a low-melting-point resin, non-low-melting-point resin particles, and wood particles to form a molded body. The low-melting-point resin has a melting point in the range of 80°C or higher and less than 190°C. The non-low-melting-point resin particles comprise at least one of a high-melting-point resin with a melting point of 190°C or higher and a thermosetting resin, and the average major diameter of the non-low-melting-point resin particles is less than 3.0 mm. The average major diameter of the wood particles is less than 3.0 mm. The molded body is then pulverized to obtain pulverized material, which is then graded.

[0104] (Postscript 10)

[0105] A mortar comprising cement and any one of the following notes 1 to 8.

[0106] (Postscript 11)

[0107] A type of concrete comprising cement and any one of the following notes 1 to 8: lightweight aggregate.

[0108] Symbol Explanation

[0109] 1… Lightweight aggregate, 10… Granular portion, 10a… Surface, 11… Low-melting-point resin, 12… Non-low-melting-point resin particles, 13… Wood particles, 20… Protrusions

Claims

1. A lightweight bone material, comprising granules having protrusions with an average diameter of less than 3.0 mm dispersed on its surface, wherein the arithmetic mean roughness Ra of the surface excluding the protrusions is in the range of 10 μm to 100 μm, and the density is 0.9 g / cm³. 3 ~1.3g / cm 3 Within the range.

2. The lightweight bone material according to claim 1, wherein, It comprises a low-melting-point resin, as well as non-low-melting-point resin particles and wood particles dispersed in the low-melting-point resin. The melting point of the low-melting-point resin is in the range of above 80°C and below 190°C. The non-low melting point resin particles comprise at least one of high melting point resins with a melting point above 190°C and thermosetting resins. The protrusion is formed by at least one of the non-low melting point resin particles and the wood particles.

3. The lightweight bone material according to claim 1 or 2, wherein, The average number of protrusions in each of the lightweight bone materials is in the range of 5 to 100.

4. The lightweight bone material according to any one of claims 1 to 3, wherein, The average height of the protrusion is in the range of 0.4 mm to 2.0 mm.

5. The lightweight bone material according to any one of claims 1 to 4, wherein, The residue measured using a 2.5mm mesh sieve was over 95% by mass. The residue measured using a 5.0mm mesh sieve is less than 15% by mass.

6. The lightweight bone material according to any one of claims 1 to 5, wherein, The residue measured using a sieve with a mesh size of 5.0 mm was 85% or more by mass.

7. A lightweight aggregate comprising granular materials with protrusions having an average diameter of less than 3.0 mm dispersed on its surface. It comprises a low-melting-point resin, as well as non-low-melting-point resin particles and wood particles dispersed in the low-melting-point resin. The melting point of the low-melting-point resin is in the range of above 80°C and below 190°C. The non-low melting point resin particles comprise at least one of high melting point resins with a melting point above 190°C and thermosetting resins. The protrusion is formed by at least one of the non-low melting point resin particles and the wood particles.

8. The lightweight bone material according to claim 7, wherein, The low-melting-point resin and the non-low-melting-point resin particles are derived from plastic waste.

9. A method for manufacturing lightweight aggregate, comprising extruding a mixture containing a low-melting-point resin, non-low-melting-point resin particles, and wood particles to form a molded body, wherein the low-melting-point resin has a melting point in the range of 80°C or higher and less than 190°C, the non-low-melting-point resin particles comprise at least one of a high-melting-point resin with a melting point of 190°C or higher and a thermosetting resin, and the average major diameter of the non-low-melting-point resin particles is less than 3.0 mm, and the average major diameter of the wood particles is less than 3.0 mm. The molded body is crushed to obtain pulverized material. The pulverized material is then classified.

10. A mortar comprising cement and lightweight aggregate as described in any one of claims 1 to 8.

11. A type of concrete comprising cement and lightweight aggregate as claimed in any one of claims 1 to 8.

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