Method and apparatus for manufacturing recycled aggregate

Abstract

To provide a method and an apparatus for manufacturing a recycled aggregate, capable of manufacturing a high-quality recycled aggregate.SOLUTION: A method for manufacturing a recycled aggregate 3 includes a crushing step of crushing original concrete 2, a classifying step of classifying an intermediate product 7, which is a component crushed in the crushing step, while washing with water, and an adding step of adding a surfactant S while stirring the intermediate product 7 classified by the classifying step, wherein the intermediate product 7 whose surface is coated with the surfactant S is recovered as the recycled aggregate 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for producing recycled aggregate from raw concrete. [Background technology]

[0002] Conventionally, recycled aggregates used in concrete mix design, mixing, and pouring are classified into grades H, M, and L, with the scope of application determined by JIS standards and regulations regarding water absorption. High-quality, stable strength, and durability require recycled aggregates with low water absorption, such as grade M or even grade H. To obtain such recycled aggregates with low water absorption, it is necessary to further grind the concrete debris that constitutes the raw concrete, classify the components, and then remove cement and other components adhering to the periphery of the aggregate (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 114526 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since there is no reliable technology for grinding, especially for fine aggregate with a particle size of 5 mm or less, most of this fine aggregate is treated as L-class and is not highly rated as a mixing material, so it is sometimes not used and is disposed of as industrial waste as fine sand.

[0005] The present invention has been made in consideration of the above points, and an object of the present invention is to provide a method and an apparatus for producing recycled aggregate that are capable of producing high-quality recycled aggregate. [Means for solving the problem]

[0006] The method for producing recycled aggregate of the present invention comprises a crushing step of crushing raw concrete, a classification step of classifying the intermediates that are the components crushed in the crushing step while washing them with water, and an addition step of adding a surfactant to the intermediates classified in the classification step while stirring them, and recovering the intermediates whose surfaces are coated with the surfactant as recycled aggregate. [Effects of the Invention]

[0007] According to the present invention, it is possible to produce high-quality recycled aggregate. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an explanatory diagram showing a recycled aggregate manufacturing apparatus used in a recycled aggregate manufacturing method according to one embodiment of the present invention; [Figure 2] FIG. 2 is an explanatory diagram schematically showing an example of a classification means of the recycled aggregate manufacturing apparatus. [Figure 3] FIG. 2 is an explanatory diagram schematically showing a part of the recycled aggregate manufacturing apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] In Fig. 1, reference numeral 1 denotes a recycled aggregate manufacturing apparatus. Hereinafter, the recycled aggregate manufacturing apparatus 1 will be simply referred to as the manufacturing apparatus 1. The manufacturing apparatus 1 uses raw concrete 2 to manufacture recycled aggregate 3 for concrete.

[0011] Raw concrete 2 is also called concrete waste, concrete rubble, etc. Raw concrete 2 is concrete mass generated by the demolition of a structure, or hardened concrete products or returned concrete (return concrete) from ready-mixed concrete, and has traditionally been discarded.

[0012] The JIS standard defines the grades H, M, and L for recycled aggregate 3. For example, H-grade recycled aggregate is specified in JIS A 5021, M-grade recycled aggregate in JIS A 5022, and L-grade recycled aggregate in JIS A 5023. In particular, the water absorption rate is specified for H-grade recycled aggregate 3. Recycled aggregate containing residual cement (cement paste) from the original concrete 2 has a higher water absorption rate than ordinary aggregate, and is therefore often classified as L-grade. Recycled aggregate with a high water absorption rate can adversely affect the properties of ready-mixed concrete when used in the concrete, and can easily caking occur during storage. The manufacturing apparatus 1 of this embodiment produces recycled aggregate 3 with a low water absorption rate, which corresponds to H-grade (recycled aggregate for concrete H).

[0013] The manufacturing apparatus 1 includes crushing means 5 for crushing raw concrete 2 into particles of a predetermined particle size or smaller. As the crushing means 5, a general concrete crusher such as a jaw crusher or impact crusher is preferably used.

[0014] The manufacturing apparatus 1 also includes a classification unit 6. The classification unit 6 classifies intermediate bodies 7, which are components of the raw concrete 2 pulverized by the pulverization unit 5. The classification unit 6 classifies the intermediate bodies 7 according to their particle size while washing them with water. As shown in FIG. 2, the classification unit 6 includes a classification main unit 10 and a water washing unit 11. In this embodiment, the classification main unit 10 classifies the intermediate bodies 7 into a plurality of particle sizes. In the illustrated example, the classification main unit 10 classifies the intermediate bodies 7 into a first intermediate body 7a, which corresponds to the largest particle size, e.g., coarse aggregate having a particle size of approximately 5 to 20 mm; a second intermediate body 7b, which corresponds to the second largest particle size, e.g., fine aggregate having a particle size of 5 mm or less; and an unnecessary portion 7c, which corresponds to the smallest particle size, i.e., fine sand. Any classifier may be used as the classification main unit 10, but a vibrating sieve is preferably used. In this embodiment, the classification main body 10 has a first classification means 10a and a second classification means 10b arranged in two stages, one above the other. A first receiving section 12a for receiving the first intermediates 7a is arranged at the discharge section of the first classification means 10a, a second receiving section 12b for receiving the second intermediates 7b is arranged at the discharge section of the second classification means 10b, and a third receiving section 12c for receiving the unwanted parts 7c is arranged below the second classification means 10b in the lower stage.

[0015] The water washing unit 11 is a means for washing the intermediate bodies 7 to be classified by supplying water W to the intermediate bodies 7 passing through the classification main body 10. The water washing unit 11 has a water supply pipe connected to a water supply source, a valve for adjusting the amount of water supplied, a nozzle, etc., and is arranged so that water W is injected under pressure like a shower from above the first classification means 10a, thereby removing unnecessary components 7c and washing the intermediate bodies 7a and 7b.

[0016] 1, the manufacturing apparatus 1 is also provided with a stirring means 15. The first intermediate 7a and the second intermediate 7b classified by the classification means 6 are sent to the stirring means 15 together with the moisture W via a conveying means such as a belt conveyor.

[0017] The stirring means 15 accommodates and stirs the intermediate 7 classified by the classification means 6 together with the water content W. As shown in FIG. 3, the stirring means 15 has a storage section 16 such as a pit, and an agitating blade 17 arranged in the storage section 16. In this embodiment, the stirring means 15 includes a first stirring means 15a that accommodates and stirs the first intermediate 7a together with the water content W, and a second stirring means 15b that accommodates and stirs the second intermediate 7b together with the water content W. The first stirring means 15a has a first storage section 16a and a first agitating blade 17a, and the second stirring means 15b has a second storage section 16b and a second agitating blade 17b.

[0018] As shown in FIG. 1, the production apparatus 1 also includes an adding means 20 that adds a surfactant S to the intermediate 7 in the stirring means 15.

[0019] Here, the surfactant S is a coating agent for forming a coating portion that coats the minute irregularities and pores on the surface of the intermediate 7, thereby reducing the specific surface area (BET specific surface area). Any surfactant may be used as the surfactant S, but fatty acid surfactants, for example, are preferably used. The surfactant S is supplied in liquid form, which makes it possible to form a uniform coating portion. In this embodiment, the surfactant S is used in the form of a solution that is 100 times the original solution, i.e., a 1% solution.

[0020] 3, the adding means 20 includes a first adding means 20a that adds a surfactant S to the first intermediate 7a accommodated in the first accommodation section 16a of the first stirring means 15a, and a second adding means 20b that adds a surfactant S to the second intermediate 7b accommodated in the second accommodation section 16b of the second stirring means 15b. The surfactant S added by the first adding means 20a and the surfactant S added by the second adding means 20b may be the same or different.

[0021] 1, the manufacturing apparatus 1 further includes a recovery means 22. The recovery means 22 recovers the intermediate 7, which has been agitated by the agitation means 15 and whose surface is coated with the surfactant S, as recycled aggregate 3. The recovery means 22 is a dehydration means that dehydrates and dries the intermediate 7 discharged from the agitation means 15 to produce recycled aggregate 3. In this embodiment, the recovery means 22 includes a first recovery means 22a that recovers the first intermediate 7a as recycled aggregate 3, which is coarse aggregate, and a second recovery means 22b that recovers the second intermediate 7b as recycled aggregate 3, which is fine aggregate, as shown in FIG.

[0022] Next, a method for producing the recycled aggregate 3 using the production apparatus 1 of this embodiment will be described.

[0023] As shown in FIGS. 1 to 3, first, raw concrete 2 supplied to crushing means 5 is crushed by the crushing means 5 to particles of a predetermined particle size or less (crushing step).

[0024] Next, intermediate bodies 7, which are components of the pulverized raw concrete 2, are classified while being washed with water in classification means 6 (classification step). In this embodiment, the intermediate bodies 7 are supplied onto first classification means 10a, and water W is supplied under pressure by water washing section 11. As a result, a portion of the intermediate bodies 7 remains on first classification means 10a and is transported together with water W to first receiving section 12a, and the intermediate bodies 7 sifted out by first classification means 10a are supplied onto second classification means 10b below together with water W. Furthermore, a portion of the intermediate bodies 7 remaining on second classification means 10b is transported together with water W by second classification means 10b to second receiving section 12b, and the unnecessary parts 7c sifted out by second classification means 10b are received together with water W in third receiving section 12c, becoming muddy water mixed with fine sand.

[0025] Furthermore, of the classified intermediates 7, the first intermediate 7a and the second intermediate 7b are transported and stored in the storage section 16 of the stirring means 15 by a transport means, and while being stirred by the stirring blades 17, surfactant S is added by the addition means 20, and the surface of the intermediates 7 is coated with surfactant S (addition process).

[0026] In this embodiment, the first intermediate 7a is placed in the first storage section 16a of the first stirring means 15a together with the water W, and then the surfactant S is added by the first adding means 20a while stirring with the first stirring blade 17a. Similarly, the second intermediate 7b is placed in the second storage section 16b of the second stirring means 15b together with the water W, and then the surfactant S is added by the second adding means 20b while stirring with the second stirring blade 17b.

[0027] Therefore, the surface of the intermediate 7 is coated with the added surfactant S, reducing the specific surface area (BET specific surface area), and the amount of water adsorbed to the unevenness and pores on the surface of the intermediate 7 decreases, resulting in a decrease in the water absorption rate.

[0028] Then, when the agitation by the agitation means 15 is completed, the intermediate body 7 is transported from the storage section 16 to the recovery means 22, where it is dehydrated and dried, and the recycled aggregate 3 is recovered (recovery step).

[0029] That is, in this embodiment, the first intermediate 7a is dehydrated and dried by the first recovery means 22a to recover the recycled aggregate 3, which is a coarse aggregate, and the second intermediate 7b is dehydrated and dried by the second recovery means 22b to recover the recycled aggregate 3, which is a fine aggregate.

[0030] In this way, intermediate 7, which is a component obtained by crushing raw concrete 2, is washed with water and classified, and surfactant S is added to the classified intermediate 7 while stirring it, and the intermediate 7 whose surface is coated with surfactant S is recovered as recycled aggregate 3.This reduces the specific surface area (BET specific surface area) of the recycled aggregate 3, and makes it possible to produce high-quality recycled aggregate 3 equivalent to H class, with a water absorption rate that is reduced to, for example, 1 / 5 to 1 / 20 of that of intermediate 7.

[0031] The powder 2 produced in this way can be used safely and securely as a mix material for fresh concrete, for example. Furthermore, the grinding process that was previously required to improve the quality of recycled aggregate has been eliminated, and the quality has been improved by coating with surfactant S, so that the grade of water absorption can be effectively improved, especially for fine aggregate recycled aggregate 3.

[0032] Furthermore, since high-quality recycled aggregate 3 can be efficiently produced from raw concrete 2, raw concrete 2 can be effectively reused, which contributes to saving resources and reducing industrial waste. [Explanation of symbols]

[0033] 1. Recycled aggregate manufacturing equipment 2 Raw concrete 3. Recycled aggregate 5. Crushing Method 6 Classification means 7 Intermediates 7a First intermediate 7b Second intermediate 15 Stirring means 15a First stirring means 15b Second stirring means 20 Means of addition 20a First addition means 20b Second addition means 22 Recovery Methods S surfactant W Moisture

Claims

1. a crushing step of crushing raw concrete; a classification step in which the intermediate, which is the component pulverized in this pulverization step, is classified while being washed with water; an addition step of adding a surfactant while stirring the intermediate product classified by the classification step, The intermediate body whose surface is coated with the surfactant is collected as recycled aggregate. A method for producing recycled aggregate, characterized by:

2. In the adding step, a surfactant is added to the first intermediate, which is the largest, and the second intermediate, which is the second largest, of the intermediates classified in the classification step, while stirring them separately.

2. The method for producing recycled aggregate according to claim 1.

3. a crushing means for crushing raw concrete; a classification means for washing with water and classifying the intermediate product, which is the component pulverized by the pulverization means; a stirring means for containing and stirring the intermediate product classified by the classification means together with water; adding means for adding a surfactant to the intermediate contained in the stirring means; a recovery means for recovering the intermediate product, the surface of which has been agitated by the agitation means and coated with the surfactant, as recycled aggregate; A recycled aggregate manufacturing apparatus comprising:

4. The stirring means is a first stirring means for accommodating a first intermediate, which is the largest among the intermediates classified by the classification means, together with water; a second stirring means for accommodating a second intermediate, which is the second largest among the intermediates classified by the classifying means, together with water; The means of addition is a first adding means for adding a surfactant to the first intermediate contained in the first stirring means; and a second adding means for adding a surfactant to the second intermediate contained in the second stirring means.

4. The recycled aggregate manufacturing apparatus according to claim 3.

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