Methods for collecting concrete waste

Abstract

This document provides a method for collecting concrete waste. [Solution] A method for recovering concrete residue, in which a water-absorbing resin and concrete residue are first mixed to form a preliminary mixture, the water content of the concrete residue being 8.33% to 25%, and the weight ratio of water in the water-absorbing resin to the concrete residue being 1:1 to 1:20, and then a stirring operation is performed on the preliminary mixture to obtain concrete recovery material. This improves the fluidity of the concrete recovery material, making recovery easier.

Description

Technical Field

[0001] The present invention relates to a method for recovering concrete residues, and more particularly to a method for recovering concrete residues using a water-absorbing resin.

Background Art

[0002] In recent years, due to the rapid development of social and economic activities, major public works such as general construction work and transportation construction have increased, and the amount of earth and stone left by their construction has become extremely large. The amount of earth and stone left includes calculation errors of concrete, the influence of the weather, or concrete residues generated during the construction process.

[0003] Conventionally, it has been generally known that concrete residues remaining in ready-mix concrete trucks or on-site concrete mixing plants are washed with a large amount of water to generate concrete recovery materials. Concrete recovery materials are classified as general business waste by the Environmental Protection Agency, and their treatment requires extra costs. In addition, the concrete recovery materials generated thereby contain hydrated calcium salts, gravel and grit, and a large amount of water, so they are difficult to aggregate and harden, their appearance is like sludge, and subsequent treatment and application are also quite difficult.

[0004] Conventional concrete waste treatment systems, for example, place concrete wastewater into a sedimentation tank to allow it to settle, then use a pump to extract wastewater with a low sludge content from the upper layer of the sedimentation tank for filtration (e.g., the waste sludge treatment and reuse equipment for ready-mix concrete plants, published in Taiwan's New Patent Publication No. TW M636970). However, this type of wastewater treatment has drawbacks: long settling times, the need for multiple sedimentation tanks, low treatment efficiency, and the tendency for mud and sand to solidify at the bottom of the sedimentation tank after prolonged use, making it impossible to recover and reuse the sand, stones, and mud, leading to waste of construction resources. There are also other concrete wastewater purification systems that use a filter core attached to a centrifugal barrel to filter the wastewater (e.g., Chinese Patent Publication No. CN117504407A). Alternatively, Chinese Patent Publication No. CN116328895A provides a concrete recovery treatment system equipped with different sorting equipment. However, all of the above methods require the purchase of additional equipment, increasing operating costs, and using conventional sedimentation tanks has the disadvantage of consuming water resources. [Overview of the project] [Problems that the invention aims to solve]

[0005] In light of this, there is a need to provide a method for recovering concrete waste that reduces the wasteful use of water resources and is relatively simple. [Means for solving the problem]

[0006] One aspect of the present invention provides a method for recovering concrete residue by mixing a water-absorbent resin with concrete residue, thereby facilitating the recovery of concrete residue.

[0007] According to one aspect of the present invention, a method for recovering concrete residue is provided. In this method, first, a water-absorbing resin and concrete residue are mixed to form a preliminary mixture, the water content of the concrete residue being 8.33% to 25%, and the weight ratio of water in the water-absorbing resin to the concrete residue being 1:1 to 1:20. Then, the preliminary mixture is stirred to obtain the recovered concrete material.

[0008] According to one embodiment of the present invention, the concrete residue comprises cement containing tricalcium silicate (3CaO·SiO2), dicalcium silicate (β-2CaO·SiO2), tricalcium aluminate (3CaO·Al2O3), tetracalcium iron aluminate (4CaO·Al2O3·Fe2O3), or any combination thereof.

[0009] According to one embodiment of the present invention, the water-absorbing resin comprises a polyacrylate salt.

[0010] According to one embodiment of the present invention, the superabsorbent resin has a free absorption capacity greater than 10 g / g in a 3.5 wt% salt solution.

[0011] According to one embodiment of the present invention, the water-absorbing resin has an average particle size of 0.05 mm to 3.00 mm.

[0012] According to one embodiment of the present invention, the water-absorbing resin is contained in an amount of 3.5 wt% to 8.5 wt% of 100 wt% of the weight of the concrete residue.

[0013] According to one embodiment of the present invention, the mixing time between the mixed water-absorbent resin and the concrete residue is 1 to 5 minutes.

[0014] According to one embodiment of the present invention, the concrete recovery material has a moisture content less than 5%.

[0015] According to one embodiment of the present invention, the method further comprises selecting the concrete recovery material and calculating the coarseness ratio which is 2.3 to 3.1.

[0016] According to one embodiment of the present invention, the concrete residue includes gravel and grit, and the method further comprises sieving the concrete recovery material to separate the gravel and grit. [Effects of the Invention]

[0017] By applying the water-absorbing resin and its manufacturing method of the present invention, a specific proportion of the water-absorbing resin can be mixed with concrete residue having a specific water content to improve the fluidity of the recovered concrete material and facilitate the separation of coarse and fine particles within it. [Modes for carrying out the invention]

[0018] As used in this text, "around," "about," "approximately," or "substantially" generally indicate that a value or range falls within 20%, 10%, or 5% of the given number or range.

[0019] The manufacturing and use of embodiments of the present invention will be examined in detail below. However, it should be understood that the embodiments provide numerous applicable inventive concepts that can be implemented in various specific ways. The specific embodiments examined are for illustrative purposes only and do not limit the scope of the present invention.

[0020] As described above, the present invention provides a method for recovering concrete residues that improves the fluidity of the recovered concrete material and facilitates the separation of coarse and fine particles within it, by mixing a specific amount of water-absorbing resin with the concrete residues based on the moisture content of the concrete residues.

[0021] The method for recovering concrete residue provided in the present invention includes first mixing concrete residue with a water-absorbent resin to obtain a preliminary mixture. In some embodiments, the concrete residue is unhardened concrete residue left in a concrete mixing device (e.g., a ready-mix concrete truck or a concrete preliminary mixing plant installed at a construction site), but the present invention is not limited thereto, and the concrete residue may be unhardened concrete residue left over from any construction work.

[0022] In some embodiments, the uncured concrete residue contains cement, pellets, and mixing water. The cement may be Portland cement, blast furnace slag powder (fine powder obtained by pulverizing blast furnace slag from the water quenching of steel mills), or fly ash (coal ash from coal-fired power plants). The pellets contain coarse aggregate (gravel or crushed stone) and fine aggregate (grit). In some embodiments, the concrete residue contains composite materials such as cement, gravel, and grit. In the above embodiments, the cement contains tricalcium silicate (3CaO·SiO2), dicalcium silicate (β-2CaO·SiO2), tricalcium aluminate (3CaO·Al2O3), tetracalcium aluminoferrite (4CaO·Al2O3·Fe2O3), or any combination thereof.

[0023] In some embodiments, the water-absorbing resin has a free absorption amount of more than about 10 g / g, preferably more than 20 g / g, with respect to 3.5 wt% of brine. The water-absorbing resin having the above free absorption amount has an excellent water absorption effect in the concrete residue.

[0024] In some embodiments, the water-absorbing resin contains polyacrylate. As an example, the preparation method of polyacrylate includes first performing a radical polymerization reaction on an unsaturated monomer aqueous solution. In some embodiments, the neutralization rate of the unsaturated monomer aqueous solution is about 55 mol% to about 80 mol%. The unsaturated monomer aqueous solution contains acid group monomers having unsaturated double bonds such as acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropane sulfonic acid, maleic acid (cis-butenyl acid), cis-butenyl anhydride, fumaric acid (trans-butenyl acid), and trans-butenyl anhydride. The unsaturated monomer aqueous solution contains one type of monomer, but is not limited thereto, and two or more types of monomer aqueous solutions may be selected.

[0025] In other embodiments, other hydrophilic monomers having unsaturated double bonds, such as acrylamide, methacrylamide, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, methyl acrylate, ethyl acrylate, dimethylamine acrylamide, and trimethylamine chloride acrylamide group, may be selectively added. The amount of hydrophilic monomer added should, in principle, not impair the physical properties of the water-absorbing resin (e.g., retention capacity and absorption rate).

[0026] In some embodiments, the method for preparing the polyacrylate salt includes adding a radical polymerization crosslinking agent to endow the water-absorbing resin composition with an appropriate degree of crosslinking and improve the processability of the water-absorbing resin composition after the polymerization reaction. In some embodiments, the radical polymerization crosslinking agent may be selected from compounds containing two or more unsaturated double bonds such as, for example, N,N-bis(2-propenyl)amine, N,N-methylenebisacrylamide, N,N-methylenebismethacrylamide, propyl acrylate, ethylene glycol diacrylate, polyethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, glycerin trimethacrylate, triacrylate or trimethacrylate of glycerin-added ethylene oxide, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, N,N,N-tris(2-propenyl)amine, ethylene glycol diacrylate, polyoxyethylene glycerin triacrylate, diethyl polyoxyethylene glycerin triacrylate, dipropylene triglycol ester, etc. Alternatively, compounds containing two or more epoxy groups such as, for example, sorbitol polyglycidyl ether, polypropylene triol polyglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, dipropylene triol polyglycidyl ether may be selected. One kind of the radical polymerization crosslinking agent may be used alone or two or more kinds may be used. In some embodiments, the solid content of the unsaturated monomer aqueous solution is 100 wt%, and the radical polymerization crosslinking agent is 0.001 wt% to 5 wt%, preferably 0.01 wt% to 3 wt%. When the addition amount of the radical polymerization crosslinking agent is within the above range, the crosslinked core structure formed after the reaction has excellent mechanical properties, is advantageous for machining, and the water-absorbing resin produced thereafter has excellent water absorption.

[0027] [[ID=,4]]In some embodiments, the above radical polymerization reaction may be carried out in a batch-type reaction vessel or a conveyor-type reactor.

[0028] In some examples, the gel obtained after the radical polymerization reaction is first cut into small gels with a diameter of 2.0 mm or less, preferably 1.0 mm or less, using a shredder. Then, the small gels are dried and further sorted. In some examples, the drying temperature may be 100°C to 180°C. By performing the drying process within this temperature range, the drying time can be effectively controlled and the degree of crosslinking can be effectively controlled, thereby preventing a large amount of unreacted monomer from remaining.

[0029] In some embodiments, the particle size of the water-absorbent resin is approximately 0.05 mm to approximately 3.00 mm, preferably approximately 0.10 mm to approximately 2.00 mm. By controlling the particle size within this range, the amount of fine powder in the product can be reduced, the absorption performance of the water-absorbent resin can be improved, and deterioration of the separation efficiency between coarse and fine particles due to particle expansion after mixing with concrete residue can be avoided.

[0030] In some examples, the amount of water-absorbing resin used is approximately 3.5 wt% to 8.5 wt%, preferably approximately 4.0 wt% to 6.0 wt%, per 100 wt% of the weight of the concrete residue. By using a water-absorbing resin within this range, the water-absorbing resin and the concrete residue can be effectively mixed to absorb moisture in the concrete residue.

[0031] Concrete residue contains water, and in some examples, the water content of the concrete residue is approximately 8.33% to 25%. The main purpose of adding water-absorbing resin is to absorb water in the concrete residue. Therefore, in some examples, the weight ratio of the amount of water-absorbing resin added to the water in the concrete residue is approximately 1:1 to 1:20, preferably approximately 1:1 to 1:10. If the amount of water in the concrete residue is 20 times greater than the amount of water-absorbing resin, the absorption will be insufficient, resulting in poor dispersibility of the slurry in the concrete recovery material obtained later. If the amount of water in the concrete residue is less than the amount of water-absorbing resin used, the water-absorbing resin will not absorb enough moisture, resulting in wasted resources.

[0032] The method for recovering concrete residue includes performing a stirring operation on the premixture to obtain concrete recovery material. In some embodiments, the stirring operation is performed for about 1 minute to about 5 minutes, preferably about 1 minute to about 3 minutes. Since the aforementioned mixing time is sufficient for the water absorption of the water-absorbing resin to become saturated, effectively controlling the mixing time increases process efficiency and avoids energy waste.

[0033] In some embodiments, the recovered concrete material has a moisture content of less than 5%. Because the recovered concrete material has the aforementioned moisture content, it can be easily removed from the concrete mixing device and has excellent fluidity. In some embodiments, the method for recovering concrete residue further includes sieving the recovered concrete material to separate coarse-grained material (gravel or crushed stone) from fine-grained material (grit).

[0034] The application of the present invention will be explained below by several embodiments, but this is not intended to limit the invention, and anyone skilled in the art can make various changes and modifications as long as they do not deviate from the spirit and scope of the invention. Preparation of water-absorbent resins Preparation Example 1

[0035] Step 1-1: 437.5 g of 48 wt% sodium hydroxide aqueous solution and 583.2 g of water were taken and placed in a 2000 c.c. cone bottle, and 540 g of acrylic acid was gradually added. The sodium hydroxide / acrylic acid dropwise addition ratio was within the range of 0.85 to 0.95, and the temperature of the neutralization reaction system in the bottle was maintained at 15°C to 40°C. After completion, the temperature of the system was further controlled to 4°C to 10°C to obtain an aqueous solution of 42 parts by weight of unsaturated monomer, however, 70 mol% of the acrylic acid portion was neutralized by sodium acrylate.

[0036] Step 1-2: 1.1 g of N,N'-methylenebisacrylamide (a radical polymerization crosslinking agent) was added to the above unsaturated monomer aqueous solution, and the temperature was maintained at approximately 20°C. Then, 0.3 g of hydrogen peroxide solution, 3.6 g of sodium bisulfite, and 3.6 g of ammonium persulfate were added as polymerization initiators, and the radical polymerization reaction was carried out. The gel obtained by the reaction was then pulverized with a cutter mill, and gel particles with a diameter of 2 mm or less were selected.

[0037] Steps 1-3: After drying the gel particles at a temperature of 130°C for 2 hours, they were sorted using a screen with a fixed particle size of 0.1 mm to 0.85 mm to obtain superabsorbent resin particles with an average particle size of 425 μm.

[0038] Steps 1-4: A mixed solution of ethylene glycol, 1,4-butanediol (manufactured by Formosa Plastic Group), and methanol was placed as a surface crosslinking agent, with a volume ratio of ethylene glycol, 1,4-butanediol, and methanol of 1:1:0.5. 200 g of the above superabsorbent resin particles were mixed with the surface crosslinking agent and heat-treated at 150°C for 1 hour. After cooling, a superabsorbent resin with the number RC100 was obtained. The free absorption capacity of superabsorbent resin RC100 in a 3.5 wt% brine solution was 20 g / g. Preparation Example 2

[0039] Step 2-1: 437.5 g of 48 wt% sodium hydroxide aqueous solution and 583.2 g of water were taken and placed in a 2000 c.c. cone bottle, and 180 g of acrylic acid was gradually added. The sodium hydroxide / acrylic acid dropping ratio was within the range of 0.85 to 0.95, and the temperature of the neutralization reaction system in the bottle was maintained at 15°C to 40°C. Then, 360 g of acrylic acid (with a sodium hydroxide / acrylic acid dropping ratio within the range of 0.85 to 0.95) was gradually added, and after the dropping was completed, the temperature of the system was further controlled to 4°C to 10°C to obtain an unsaturated monomer aqueous solution of 42 parts by weight of monomer, however, 70 mol% of the acrylic acid portion was neutralized by sodium acrylate.

[0040] Step 2-2: 1.5 g of N,N'-methylenebisacrylamide (a radical polymerization crosslinking agent) was added to the above unsaturated monomer aqueous solution, and the temperature was maintained at approximately 20°C. Then, 0.3 g of hydrogen peroxide solution, 3.6 g of sodium bisulfite, and 3.6 g of ammonium persulfate were added as polymerization initiators, and the radical polymerization reaction was carried out. The gel obtained by the reaction was then pulverized with a cutter mill, and gel particles with a diameter of 2 mm or less were selected.

[0041] Step 2-3: After drying the gel particles at a temperature of 130°C for 2 hours, they were sorted using a screen with a fixed particle size of 0.1 mm to 0.85 mm to obtain superabsorbent resin particles with an average particle size of 230 μm.

[0042] Step 2-4: A mixed solution of ethylene glycol, 1,4-butanediol (manufactured by Taiwan Plastics Co., Ltd.), and methanol was placed as a surface crosslinking agent, with a volume ratio of ethylene glycol, 1,4-butanediol, and methanol of 1:1:0.5. 200 g of the above water-absorbing resin particles were mixed with the surface crosslinking agent and heat-treated at 150°C for 1 hour. After cooling, a water-absorbing resin with the number RC200 was obtained. The water-absorbing resin RC200 had a free absorption capacity of 15 g / g in a 3.5 wt% brine solution. Evaluation format Concrete recovery materials

[0043] According to the CNS1240 concrete pellet standards, and as stated by the Geological Survey and Mining Management Center of the Ministry of Economic Affairs, the regulations for sieve analysis of fine-grained concrete require that the particle size ratio (FM) be between 2.3 and 3.1, and that the FM must not exceed 0.2 from the standard FM. The FM can be calculated using the following formula (1). Coarseness ratio (FM) = Σ (cumulative retention percentage for each sieve number) / 100 (1)

[0044] The sieve numbers, corresponding standard sieve mesh widths, and sieve passage percentages for each sieve size (FM) are shown in Table 1 below.

[0045] [Table 1] water absorbent resin

[0046] To evaluate the properties of the water-absorbing resin of the present invention, its physical properties were analyzed using the following test methods. Unless otherwise specified, all measurements below were performed under room temperature of 23±2°C and relative air humidity of 45±10%. The water-absorbing resin should be thoroughly mixed before analysis. Absorption ratio

[0047] 1g of superabsorbent resin (S1) in a nonwoven fabric tea bag (size 160 x 120mm) 2 The tea bags were placed in (blank weight W1), compressed with a hot air fan, immersed in 1L of 3.5wt% salt water for 30 minutes, removed, hung for 5 minutes, and then weighed (W2). The absorption ratio of the superabsorbent polymer was calculated using the following formula (2). Absorption ratio = (W2 - W1 - S1) / S1 (2) Particle size analysis

[0048] The particle size analysis test of the superabsorbent polymer was performed according to the measurement method specified in ERT 220.2(12) by the European Disposables and Nonwovens Association (EDANA). Example 1

[0049] The concrete residue recipe for Example 1 consisted of 3.5 kilograms of Portland cement, 8.5 kilograms of gravel, 10 kilograms of grit, and 2 kilograms of water. The concrete residue amounted to approximately 0.1 cubic meters (m³). 3The concrete residue had a moisture content of 8.33%. First, the concrete residue was placed in a horizontal twin-shaft mixer (model number: Jinlei Machinery KNER2012) and stirred at a rotation speed of 50 rpm for 1 minute to make the concrete residue into a slurry. Then, 1.5 kilograms of superabsorbent resin RC-100 was placed in the twin-shaft mixer, and the amount of superabsorbent resin RC-100 was 6.25 wt% of the concrete residue. After stirring at a rotation speed of 50 rpm for 1.5 minutes, concrete recovery material was obtained. The concrete recovery material was heat-treated in an oven at 110°C for 30 minutes, then sorted and the coarseness ratio was calculated, and the results are shown in Table 2. Examples 2-7

[0050] Examples 2 to 7 used a recovery process similar to that of Example 1, but the difference was that in Example 2, 1 kilogram of superabsorbent resin RC-200 was used at a rate of 4.17 wt% of the concrete residue; in Example 3, 1 kilogram of superabsorbent resin RC-100 was used at a rate of 4.17 wt% of the concrete residue, and the rotation speed for mixing the concrete residue and superabsorbent resin was 100 rpm; in Example 4, 1 kilogram of superabsorbent resin RC-200 was used at a rate of 4.17 wt% of the concrete residue, and the rotation speed for mixing the concrete residue and superabsorbent resin was 100 rpm; and in Example 5, 1 kilogram of superabsorbent resin RC-100 was used at a rate of 4.17 wt% of the concrete residue, and the rotation speed for mixing the concrete residue and superabsorbent resin was 100 rpm.

[0051] The concrete residue in Example 6 is the recycled cement recipe from Taiwan Patent Publication No. TW I692461, namely, 1 kilogram of Portland cement, 1 kilogram of furnace stone powder, 0.7 kilograms of fly ash, 3 kilograms of glass sand, and 1.9 kilograms of water, with a moisture content of 25% and a volume of approximately 0.03 m³. 3In Example 6, 0.3 kilograms of RC-100 superabsorbent resin, weighing 3.95 wt% of the concrete residue, was used, and the mixing speed of the concrete residue and superabsorbent resin was 100 rpm. In Example 7, the same concrete residue as in Example 6 was used, but 0.3 kilograms of RC-200 superabsorbent resin, weighing 3.95 wt% of the concrete residue, was used, and the mixing speed of the concrete residue and superabsorbent resin was 100 rpm. The process conditions and particle size ratios for each of Examples 2 to 7 are shown in Table 2. Comparative Examples 1-4

[0052] Comparative Examples 1-4 utilize a recovery process similar to Example 1, but the difference lies in the fact that Comparative Example 1 uses 0.03 kilograms of superabsorbent resin (product name: TAISAP-SK273, average particle size 100 μm, absorption ratio 10 g / g) at a dose of 0.125 wt% of the concrete residue, and the mixing time for mixing the concrete residue and superabsorbent resin is 5 minutes. Comparative Example 2 uses 2.5 kilograms of superabsorbent resin (product name: TAISAP-SK273, average particle size 100 μm, absorption ratio 10 g / g) at a dose of 10.42 wt% of the concrete residue, and the mixing time for mixing the concrete residue and superabsorbent resin is 5 minutes. The mixing time was 5 minutes. In Comparative Example 3, a dose of 3 kilograms of superabsorbent resin (product name: TAISAP-SK273, average particle size 100 μm, absorption ratio 10 g / g) was used at a rate of 12.5 wt% of the concrete residue, and the rotation speed for mixing the concrete residue and superabsorbent resin was 100 rpm. In Comparative Example 4, the same concrete residue as in Example 6 was used, but a weight of 0.03 kilograms of superabsorbent resin (product name: TAISAP-SK273, average particle size 100 μm, absorption ratio 10 g / g) was used at a rate of 3.95 wt% of the concrete residue, and the rotation speed for mixing the concrete residue and superabsorbent resin was 100 rpm. The process conditions and coarseness ratios for Comparative Examples 1 to 4 are shown in Table 3.

[0053] [Table 2]

[0054] [Table 3]

[0055] From the results of the above examples, it is verified that when a specific proportion of water-absorbing resin is mixed with concrete residue having a specific water content, the fluidity of the recovered concrete material can be improved, and the resulting recovered concrete material has a predetermined coarseness ratio.

[0056] Therefore, by applying the concrete residue recovery method of the present invention and mixing a specific amount of water-absorbing resin with the concrete residue based on the moisture content of the concrete residue, the fluidity of the recovered concrete material can be improved, making it easier to separate the coarse and fine particles within it.

[0057] Although the present invention has been disclosed above by several embodiments, these embodiments are not intended to limit the present invention, and any person skilled in the art can make any changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention is as defined by the scope of the patent application appended later.

Claims

1. A method for collecting concrete waste, A premixture is formed by mixing a water-absorbing resin with the concrete residue, wherein the water content of the concrete residue is 8.33% to 25%, and the weight ratio of the water-absorbing resin to the water in the concrete residue is 1:1 to 1:6.

3. The aforementioned premix is ​​stirred to obtain concrete recovery material. A method for recovering concrete residue, comprising the following features.

2. The aforementioned concrete residue is tricalcium silicate (3CaO・SiO ２ ), dicalcium silicate (β-2CaO・SiO ２ ), tricalcium aluminate (3CaO・Al ２ O ３ ), tetracalcium iron aluminate (4CaO・Al ２ O ３ Fe ２ O ３ A method for recovering concrete residue according to claim 1, comprising cement containing ) or any combination thereof.

3. The method for recovering concrete residue according to claim 1, wherein the water-absorbing resin comprises a polyacrylate salt.

4. The method for recovering concrete residue according to claim 1, wherein the superabsorbent resin has a free absorption capacity of more than 10 g / g in a 3.5 wt% salt solution.

5. The method for recovering concrete residue according to claim 1, wherein the water-absorbing resin has an average particle size of 0.05 mm to 3.00 mm.

6. The method for recovering concrete residue according to claim 1, wherein the water-absorbing resin is contained in an amount of 3.5 wt% to 8.5 wt% of 100 wt% of the weight of the concrete residue.

7. The method for recovering concrete residue according to claim 1, wherein the stirring operation is performed for a duration of 1 to 5 minutes.

8. The method for recovering concrete residue according to claim 1, wherein the recovered concrete material has a moisture content less than 5%.

9. The method for recovering concrete residue according to claim 1, further comprising selecting the recovered concrete material and calculating the coarseness ratio which is 2.3 to 3.

1.

10. The concrete residue includes gravel and grit, and the method is The method for recovering concrete residue according to claim 1, further comprising sieving the recovered concrete material to separate the gravel and the grit.

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