Block and method for manufacturing the same

Abstract

To provide: a block of novel composition, which comprises waste materials such as a gypsum board waste material and a sieve residue; and a method for producing the same.SOLUTION: The present invention is a method for producing a block including the following steps: (a) mixing a raw material including either or both of a sieve residue and waste gypsum and recycled concrete with a solidifier, an insolubilizer, an admixture, and water to produce a mixture; (b) filling the mixture into a prescribed formwork; (c) curing the mixture filled into the formwork for a prescribed period; and (d) removing the formwork after the curing to obtain a block containing the raw material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a block and a method for manufacturing the same, and particularly to a block containing waste such as waste gypsum board and a method for manufacturing the same.

Background Art

[0002] Conventionally, new construction waste gypsum board generated when constructing a new house is separated into gypsum and paper, and then, for example, as a raw material for gypsum board, gypsum for cement addition, or as a soil (ground) improvement material or solidifying material, a part of it is recycled. However, the recycling rate of demolition waste gypsum board generated from the demolition of houses and the like is extremely low. One of the reasons is problems such as the elution of harmful heavy metals (arsenic, cadmium, fluorine) and the generation of hydrogen sulfide.

[0003] In order to prevent the elution of this harmful heavy metal, there is a method of solidifying and confining the gypsum recovered from the waste gypsum board after demolition with a cement material. However, there is another problem such as the elution of hexavalent chromium derived from the cement material. As a countermeasure for suppressing the elution of hexavalent chromium, the addition of a reducing agent such as ferrous sulfate has been conventionally known.

[0004] In addition, the applicant has proposed and implemented a method for manufacturing reusable granulated products from waste gypsum board as a method for reusing waste gypsum board that can suppress the elution of harmful heavy metals and the generation of hydrogen sulfide (Patent Document 1), and further proposed and implemented the use of the granulated products as recycled roadbed materials for asphalt pavement (Patent Document 2).

[0005] Furthermore, the residue generated when stable industrial waste is separated from construction mixed waste (so-called "sieve residue") cannot be treated as stable industrial waste. Therefore, it cannot be disposed of in stable waste disposal sites and must be properly treated in controlled waste disposal sites. However, controlled waste disposal sites are also facing a shortage of remaining landfill capacity, and the limited number of receiving sites is a problem. In addition, because the sieve residue has fine particles and looks like sand from a distance, illegal dumping and improper disposal are problematic.

[0006] Regarding prior art related to cement solidification (blocking) that includes waste as a raw material, Patent Document 3 discloses concrete blocks containing building material waste and a method for manufacturing the same. Furthermore, regarding prior art related to the solidification of granules, Patent Document 4 discloses a method for manufacturing concrete products that utilize granules.

[0007] However, Patent Document 3 does not describe the use of sieve residue as a raw material or the suppression of the elution of harmful heavy metals. Patent Document 4 uses granulated coal ash as a raw material and does not use gypsum board waste or sieve residue. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 6053004 [Patent Document 2] Japanese Patent Publication No. 2014-177795 [Patent Document 3] Japanese Patent Publication No. 2002-201060 [Patent Document 4] Patent No. 5474036 [Overview of the project] [Problems that the invention aims to solve]

[0009] The present invention aims to provide a block and a method for manufacturing the same that can be used to recycle waste materials such as gypsum board waste and sieving residue. [Means for solving the problem]

[0010] In one aspect of the present invention, a block is provided obtained by mixing a raw material containing either or both of sieve residue and waste gypsum, recycled concrete, a solidifying agent, an immobilizing agent, an admixture, and water, placing the mixture in a mold, solidifying it, and curing it.

[0011] In another aspect of the present invention, a method for producing a block is provided, comprising the steps of: (a) mixing raw materials, which include either or both of sieve residue and waste gypsum, with recycled concrete, with a solidifying agent, an immobilizing agent, an admixture, and water to produce a mixed product; (b) filling the mixed product into a predetermined mold; (c) curing the mixed product after filling the mold for a predetermined period of time; and (d) removing the mold after curing to obtain a block containing the raw materials. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows the steps for manufacturing a block according to one embodiment of the present invention. [Figure 2] This is a schematic diagram showing the composition of roadbed material including crushed blocks according to one embodiment of the present invention. [Figure 3] This is a diagram showing a compound according to one embodiment of the present invention. [Figure 4] This figure shows a compound filled into a cylindrical mold according to one embodiment of the present invention. [Figure 5] This is a diagram showing a cylindrical block according to one embodiment of the present invention. [Figure 6] This figure shows a compound filled into a rectangular mold according to one embodiment of the present invention. [Figure 7] This is a diagram showing a rectangular block of one embodiment of the present invention. [Figure 8] This figure shows the state (crushed material) of a block after crushing according to one embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] Embodiments of the present invention will be described while referring to the drawings. FIG. 1 is a diagram showing the steps of a method for manufacturing blocks according to an embodiment of the present invention. The manufacturing process of FIG. 1 can be carried out, for example, using the facilities of an intermediate treatment facility (for example, the "zero-emission plant" owned by the applicant, etc.) for recycling construction waste.

[0014] In step S1 of FIG. 1, raw materials including either or both of screenings residue and waste gypsum and recycled concrete are kneaded with a solidifying agent, an insolubilizing agent, an admixture, and water to produce a kneaded product. Screenings residue means the residue in the sorting process such as manual sorting, air sorting, and vibrating screens of so-called construction mixed waste. Examples of the breakdown of screenings residue include tiles, bricks, glass, pottery, porcelain, concrete pieces, mortar, stone, gypsum powder, ALC, etc. Waste gypsum means pulverized gypsum board waste material (hereinafter also referred to as waste gypsum board). Recycled concrete means crushed concrete waste material as crushed stone, which can be used as so-called recycled crushed stone or recycled aggregate, and for example, 40mm under (RC-40) or 20mm under (RC-20) with a small size can be used.

[0015] As the solidifying agent, cement can be used, but it is desirable to use blast furnace cement type B in which 10 to 60% of blast furnace slag is mixed in blast furnace cement. The insolubilizing agent is used to suppress the elution of heavy metals such as lead and harmful substances such as hexavalent chromium. As the insolubilizing agent A, an iron (I) sulfide-based insolubilizing agent (for example, ferrous sulfate) and as the insolubilizing agent B, a magnesium-based insolubilizing agent (for example, magnesium oxide) can be used simultaneously or at least either one of them. As the admixture, a high-performance water reducing agent can be used. Tap water can be used as the water. Kneading can be carried out using a commercially available kneading machine (mixer).

[0016] In the kneading of Process S1, while there is a requirement to reuse as much of the raw materials (especially the sieve residue and waste gypsum) as possible, it is necessary to maintain a high strength of the manufactured blocks. Also, it is necessary to efficiently and appropriately perform the kneading and mold filling processes. Furthermore, it is necessary to suppress the elution of harmful substances in the crushed material after the block is crushed. Therefore, it is necessary to optimize the blending (mixing) conditions of each material through experiments. Specific blending conditions of the materials will be described later.

[0017] In Process S2, the kneaded material produced in Process S1 is filled into a mold. At that time, for example, it is desirable to apply vibration to the mold by a vibrator to make the kneaded material in the mold uniform. Although a mold of a normal square shape (the shape of a rectangular parallelepiped) is usually used, depending on the use (usage conditions) of the block, other shapes such as a cube, a cylindrical shape (the shape of a cylinder), etc. may be used. The fresh properties of the kneaded material affect the filling into the mold. That is, until the filling operation of the mold is completed, the kneaded material should maintain the required softness, and then it is desired to reach condensation and hardening at a normal speed. This fresh property varies greatly depending on the blending conditions of the materials during kneading, particularly the amount of water added and the timing of adding water, etc.

[0018] In Process S3, the kneaded material filled in the mold is cured for a predetermined period. For curing, steam curing (for example, a maximum temperature of 65°C) can be used instead of or in addition to normal curing (left at room temperature). The curing period can be, for example, between 2 weeks (14 days) and 4 weeks (28 days) considering the strength of the block after solidification, etc.

[0019] In Process S4, the mold is removed to obtain a solidified and cured block containing the raw materials. Then, the compressive strength (N / mm 2 ) of the block is measured. The standard (criterion for judging whether it is effective) of the compressive strength (N / mm2) is, for example, 20 N / mm 2 . Note that this criterion can be considered effective even with a value less than 20 N / mm 2 depending on the usage conditions of the block.

[0020] Steps S5 and S6 are performed after block manufacturing. In step S5, the block is crushed in a crusher to obtain crushed material. For example, a bucket crusher (crushing bucket) attached to a backhoe (crushing heavy machine) can be used for crushing. Subsequently, a heavy metal leaching test is performed on the crushed material to confirm that the leaching of harmful metals such as arsenic, fluorine, cadmium, and hexavalent chromium is below the standard value.

[0021] In process S6, the crushed blocks are used as subbase material. When used as subbase material, a subbase material test is performed beforehand to confirm that the particle size distribution, abrasion loss, plasticity index, and modified CBR are within the standard limits. Figure 2 is a schematic diagram showing the configuration of subbase material for asphalt pavement according to one embodiment of the present invention. In this invention, subbase material for asphalt pavement refers to subbase material 20 placed beneath the surface / base layer 10 containing asphalt in an asphalt pavement, and more specifically, the material of the subbase layer below the subbase material. As shown in Figure 2, the subbase material 20 includes crushed blocks 24 to fill the gaps between recycled concrete 22. [Examples]

[0022] Blocks were fabricated using waste gypsum board and sieve residue, which are raw materials for granulated stone manufactured by the applicant, Keiwa Kogyo Co., Ltd. After curing under specified conditions, the strength of the blocks was measured. The approximate target strength was 20 N / mm². 2 Experiments were conducted to find the optimal mix conditions and manufacturing methods. In the mix tests, both strength and fresh properties were verified. Fresh properties have a significant impact on handling when filling the formwork with concrete. Increasing the amount of water makes the concrete softer but reduces its strength. Therefore, 19 different test specimens (cylindrical blocks) were prepared by changing the method of adding water, such as double mixing (additional water addition). The test materials and test methods are shown below.

[0023] <Test materials> 1. Waste gypsum board: Waste gypsum board that was brought to Keiwa Zero Emission Plant Sendai was crushed into a powder and used. 2. Recycled concrete: RC-40 manufactured at Keiwa Recycling Center Sendai was used. However, the 40mm under-20mm was too large for the test specimens, so it was reduced to 20mm under-20mm (RC-20). 3. Water: Tap water was used. 4. Cement: Blast furnace type B was used. 5. Immobilizing agent A: A ferric sulfide-based immobilizing agent was used. 6. Immobilizing agent B: A magnesium-based immobilizing agent was used. 7. Admixture: The high-performance water-reducing agent "Nl4000" was used.

[0024] <Testing Method> The materials were mixed in a mixing (kneading) machine according to the specified formulation conditions, water was added, and the mixture was kneaded. The mixed material was placed into a mold and filled uniformly while being vibrated with a vibrator. Subsequently, curing was carried out using two methods: normal curing (protection at room temperature) and steam curing (maximum temperature of 65°C). <Conditions for steam curing> 2 hours: Maintain a temperature of 20°C 3 hours: Temperature rises from 20°C to 65°C 5 hours: Maintain at 65℃ Strength measurements were taken after 1 day and 14 days of steam curing. Standard curing was performed, and strength measurements were taken after 28 days. The strength of the test specimen (cylindrical block) was measured after it was removed from the formwork following curing.

[0025] As an example from the 19 tests, Figure 3 shows the appearance of the mixed material 30 after mixing. Figure 4 shows the appearance of the mixed material 34 filled into a cylindrical mold 32. Furthermore, Figure 5 shows the appearance of the test specimen (cylindrical block) 40 after it has been removed from the mold 32 after curing.

[0026] <Formulation conditions and test results> Of the 19 tests, the target strength was 20 N / mm². 2 The formulation conditions and strength measurement results for the tests that yielded the desired results are shown in Tables 1-4 below. [Table 1]

Table 2

[0027]

Table 3

Table 4

Examples

[0028] After manufacturing blocks by the above series of steps using a square mold, a test was conducted to crush the blocks into crushed materials. The blending conditions during block manufacturing are as shown in Table 5 below. Based on the results obtained from the blending tests in Example 1, three batches (A to C) were manufactured under the determined blending conditions respectively.

Table 5

[0029] Table 5A-C differ in the order in which the materials are mixed. The order in which the materials are mixed is shown below. <No.A> Mix the raw materials (sieve residue) and cement for 30 seconds. Add water (9.5L) and mix for 30 seconds. Mix waste gypsum board, RC40, and immobilizer for 30 seconds. Add water (8L) and mix for 90 seconds. <No.B> Mix the raw materials (sieve residue) and waste gypsum board for 30 seconds. Add water (9.8L) and mix for 30 seconds. Add cement, RC40, and immobilizer and mix for 30 seconds. Add water (8.4L) and mix for 90 seconds. <No.C> • Materials (sieve residue, waste gypsum board, RC40, Mix cement and immobilizer for 30 seconds. Add water (9.5L) and mix for 90 seconds.

[0030] After mixing, the mixture was packed into molds while being vibrated with a vibrator, and then steam-cured in a steam curing chamber. The next day, it was removed from the steam curing chamber, demolded, and the block was obtained. After that, it was covered with a blue tarp and cured as usual. Fourteen days later, the block was crushed using a crusher to obtain the crushed material. The crushing was done using a bucket crusher attached to a backhoe.

[0031] Figure 6 shows the mixture 38 filled into a rectangular mold 36. Figure 7 shows the removal of the rectangular mold 36 to obtain a rectangular block 42. Figure 8 shows the crushed material 44 obtained by crushing the block 42. Evaluation tests and heavy metal leaching tests were conducted on the crushed material after crushing. The test results are as follows.

[0032] <Evaluation test results> • Subgrade material testing All of the crushed material after the block crushing test met the quality standards for recycled roadbed material. • The particle size distribution obtained from sieving tests was also within the specified limits. • Weight loss due to abrasion was within the standard of 50% or less. • The plasticity index (PI) was NP (Non-Plastic), meeting the standard value of 6 or less. • The corrected CBR also showed over 80%, significantly exceeding the standard value of over 20%.

[0033] <Heavy Metal Leaching Test> The raw materials used contained levels of arsenic, fluorine, and cadmium exceeding the standard limits. However, no levels of these heavy metals exceeding the standard limits were found in the crushed material obtained by crushing the blocks produced by the method of the present invention. Therefore, it can be concluded that they were insolubilized. Regarding fluorine, ettringite, one of the hydrates of cement, also contributes to this. On the other hand, hexavalent chromium was analyzed because it is contained in cement, but no leaching was observed.

[0034] Embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to these embodiments. The present invention can be implemented in various improved, modified, and transformed forms based on the knowledge of those skilled in the art, without departing from its spirit. [Explanation of Symbols]

[0035] 10. Surface / base layer containing asphalt 20 Roadbed material (lower roadbed material) 22 RC40 24. Crushed material 30, 34, 38 Compound 32 Cylindrical formwork 36 square formwork 40 Test specimens (cylindrical blocks) 42 square blocks 44 blocks of crushed material

Claims

1. A block obtained by mixing a raw material containing sieve residue and recycled concrete, a solidifying agent, an immobilizing agent, an admixture, and water, and then solidifying and curing it in a mold, A block containing the sieved residue of the raw materials, recycled concrete, a solidifying agent, and water in a weight ratio of 4:2:1 during the mixing process.

2. A block obtained by mixing raw materials including sieve residue, waste gypsum, and recycled concrete with a solidifying agent, an immobilizing agent, an admixture, and water, and then solidifying and curing the mixture in a mold, A block containing the sieved residue of the raw materials, waste gypsum, and recycled concrete in a weight ratio of 3:1:4 during the mixing process.

3. The block according to claim 1 or 2, wherein the solidifying agent comprises blast furnace cement type B.

4. The block according to claim 2, wherein the waste gypsum includes powdered waste gypsum obtained by crushing waste gypsum board.

5. The block according to any one of claims 1 to 4, wherein the immobilizing agent comprises either or both of a ferrous sulfide-based immobilizing agent and a magnesium-based immobilizing agent.

6. The block according to any one of claims 1 to 5, wherein the admixture includes a high-performance water-reducing agent.

7. The block according to any one of claims 1 to 6, wherein the curing includes curing under steam for a predetermined period of time (steam curing).

8. Crushed material obtained by crushing a block according to any one of claims 1 to 7.

9. Roadbed material containing the crushed material according to claim 8.

10. (a) A process of mixing raw materials including sieve residue, waste gypsum, and recycled concrete with a solidifying agent, an immobilizing agent, an admixture, and water to produce a mixed product, (b) A step of filling the kneaded material into a predetermined mold, (c) A step of curing the mixture after filling the mold for a predetermined period of time, (d) A step of removing the formwork after curing to obtain a block containing the raw material, Includes, The step (a) for producing the mixed material is a method for producing a block, comprising the sieve residue, the waste gypsum, and the recycled concrete in a weight ratio of 3:1:

4.

11. (a) A process of mixing raw materials including sieve residue and recycled concrete with a solidifying agent, an immobilizing agent, an admixture, and water to produce a mixed product, (b) A step of filling the kneaded material into a predetermined mold, (c) A step of curing the mixture after filling the mold for a predetermined period of time, (d) A step of removing the formwork after curing to obtain a block containing the raw material, Includes, A method for manufacturing a block, comprising mixing the sieved residue of the raw materials, recycled concrete, a solidifying agent, and water in a weight ratio of 4:2:1 during the mixing process.

12. The manufacturing method of claim 10, wherein step (a) for producing the compound comprises, in order, mixing the sieved residue and the solidifying agent, adding the water, and mixing the waste gypsum and the recycled concrete.

13. The manufacturing method of claim 10 or 12, wherein the waste gypsum includes powdered waste gypsum obtained by crushing waste gypsum board.

14. The method for manufacturing according to any one of claims 10 to 13, wherein the immobilizing agent comprises either one or both of a ferrous sulfide-based immobilizing agent and a magnesium-based immobilizing agent.

15. The method for producing the product according to any one of claims 10 to 14, wherein the admixture includes a high-performance water-reducing agent.

16. The manufacturing method according to any one of claims 10 to 15, wherein the curing step (c) includes curing under steam for a predetermined period of time (steam curing).

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