JP5032757B2 - Manufacturing method of recycled aggregate - Google Patents

Description

  The present invention relates to a method for remanufacturing and manufacturing aggregate from concrete waste.

  Of the architectural waste generated in large quantities due to the dismantling, improvement and reconstruction of buildings, concrete waste accounts for about 40%. About 50% of this concrete waste is reused as roadbed material for road paving and backfilling, but the remaining 50% is actually discarded.

  On the other hand, a large amount of aggregate is used for concrete, but it is becoming difficult to collect high-quality natural aggregates such as gravel and river sand, which eliminates the problem of depletion of aggregate resources and makes effective use of concrete waste. From both sides, it has been studied to recycle and collect aggregates from waste concrete and reuse them as coarse aggregates and fine aggregates.

  In order to regenerate and collect aggregate from waste concrete, a method of crushing waste concrete with a crusher such as a cone crusher, a jaw crusher, or a ball mill has been attempted. However, in this method, if the material is retained in the crusher for 30 minutes or more and is not subjected to friction crushing, the most important absolute dry density and water absorption standards (absolute absorption) among the quality regulations established for JIS A5021 recycled aggregate H for concrete. It was difficult to satisfy a dry density of 2.5 kg / L or more and a coarse aggregate water absorption of 3.0% or less.

  Also, for the regeneration and collection of fine aggregates, in Patent Document 1, a centrifugal air classifier is used, and the cement paste is peeled off by colliding with a collision plate or a dispersion plate in the classifier by centrifugal force. Has been proposed. However, this method complicates the equipment, the hardness of the aggregate is high, and centrifugal force is applied at high speed rotation, so the wear of the classifier is severe and frequent repair and maintenance are required, resulting in high regeneration costs. There is a drawback of becoming.

Recently, heating and grinding methods (see Patent Documents 2 and 3) and regeneration methods using water jets have been proposed and implemented, but these methods consume a lot of energy for the regeneration of aggregates. (For example, in the case of a water jet, a power of 90 kW / h is required to obtain a processing capacity of 500 kg / h), and the cost of recycling is high in order to adopt these methods in the treatment of small-scale concrete waste materials. There's a problem. In addition, in the recycling method using a water jet, a problem of water treatment also occurs.
Japanese Patent Laid-Open No. 11-12003 Japanese Patent Laid-Open No. 8-91893 JP-A-8-109052

  The problem to be solved by the present invention is that, among the quality regulations established for JIS A5021 recycled aggregate H for concrete, recycled aggregate that satisfies the most important absolute dry density and absorptivity standards with less power and reliably. It is to provide a method that can be manufactured.

The present invention, concrete waste pre crushed to a particle size 40mm or less, in the manufacturing method of the recycled aggregate for manufacturing recycled aggregate from concrete waste material by crushing the pre-crushed concrete waste by vibrating crusher, The crushing medium to be filled in the crushing chamber of the vibratory crusher is at least two types of rod-shaped crushing medium having a rod diameter of 50 to 30 mm and rod-shaped crushing medium having a rod diameter of less than 30 to 19 mm. The medium and the small-diameter crushing medium are filled at a volume ratio of 6: 4 to 4: 6, and the crushing medium is filled at a filling rate of 50 to 20% by volume with respect to the crushing chamber volume. using machine, the pre-crushed concrete waste, particle fraction having a particle size of less than 5mm is (coarse aggregate content in the 100-concrete waste) by mass% ~ {(100- concrete waste Crushed until a selected set value within a range of coarse aggregate content) +10} of the crushing due to the vibration type crusher, a particle size 0.15mm following crushed material was removed by air classification The coarse particles having a particle diameter of 25 mm or more discharged from the vibration crusher are crushed again by the vibration crusher .

  According to the present invention, the aggregate and the combination of the crushing medium of the vibration type crusher used for the production of the regenerated aggregate are made appropriate, so that the regenerated aggregate satisfying the standard of the absolute dry density and the absorption rate can be obtained with less power. And it can be manufactured reliably and the effective use of concrete waste can be promoted.

  Further, since the crushing process by the vibration crusher is a dry process, troublesome problems such as water treatment do not occur.

  In the present invention, first, concrete waste is preliminarily crushed to a particle size of 40 mm or less. The type of the crushing apparatus used for the preliminary crushing is not limited, but it is preferable to use a dry crusher that does not use water in order to prevent the problem of water treatment later.

  The size of concrete waste varies. Therefore, it is important to set the particle size within a predetermined range by preliminary crushing so that crushing and grinding can be appropriately performed in the vibration crusher in the subsequent process. That is, if there is too much crushing and grinding action in the vibration crusher, the generation of fine powder increases, which not only lowers the product recovery rate but also increases the energy cost. Conversely, if the action of crushing and grinding is too small, the quality standard cannot be satisfied. Therefore, in order to minimize the energy cost by the optimum crushing and grinding action, the concrete waste material preliminarily crushed to 40 mm or less, preferably 25 mm or less by a crusher of any kind is used as a starting material. In this preliminary crushing stage, the proportion of particles having a particle size of 5 mm or less is about 3.5% by mass.

  After preliminary crushing, it is further crushed by a dry vibratory crusher, and aggregate is recycled from waste concrete. In concrete, strength is expressed by combining aggregates with cement paste, and in order to recycle aggregates from this concrete, the concrete is crushed in order not to destroy the contained aggregate itself, and its surface It is necessary to remove the cement paste adhering to the surface. For this reason, it is necessary to crush the concrete and peel the cement paste adhering to the surface by self-pulverization or the like, and a reprocessing machine having a crushing and grinding action is required.

  In the present invention, a vibration type crusher that has been conventionally used as a crusher (a vibration type crusher using a rod as a grinding medium) is used. The vibration type crusher expresses crushing ability by a crushing action by an impact force, a stirring and dispersing action in which the crushing medium revolves in the crusher, and a friction crushing action of the crushing medium and the crushing material, and the crushing material and the crushing material. However, if the conventional vibration type crusher is used as it is, the impact force is excessively pulverized and not only fine powder is generated and the aggregate yield is reduced, but also particles of 25 to 5 mm are collected by sieving as coarse aggregate. Even so, the water absorption rate is greatly increased due to the microcracks generated in the aggregate during pulverization.

  Therefore, in the present invention, the following measures are taken in order to reduce only the impact action while maintaining the revolution action of the vibratory crusher (specifically, maintaining the vibration amplitude and frequency).

  a) The filling amount (rate) of the crushing medium is reduced to about 80 to 30% in the case of a general vibration crusher. That is, the crushing medium is filled at a filling rate of 50 to 20% by volume with respect to the volume of the crushing chamber.

  b) In a general vibration type crusher, the rod diameters of the rods that are crushing media are all the same diameter, but in order to reduce the impact action, 40-60% of the crushing media to be filled is generally used. Change to a small crushing medium of about 85 to 60% of the rod diameter of the crushing medium used in the vibration crusher. That is, a large-diameter crushing medium (rod diameter: 50 to 30 mm) and a small-diameter crushing medium (rod diameter less than 30 to 19 mm) are filled at a volume ratio of 6: 4 to 4: 6.

The extent to which crushing and grinding are performed with a vibratory crusher is an important point for recovering aggregates that satisfy quality regulations and have a good yield. The content ratio of coarse aggregate (particle size of 5 mm or more) in concrete: X (mass%) varies depending on the concrete, but generally, as shown in Table 1, X = about 50 mass%.

  Accordingly, if the cement paste is ideally peeled from the coarse aggregate, the particle content D (% by mass) of less than 5 mm is D = 100−X = about 50, and the water absorption rate of the raw aggregate and the absolute dryness. Return to density. However, it is difficult to peel the ideal cement paste, and it is difficult to measure the cement paste in a short time.

  Therefore, in the present invention, the degree of crushing of the concrete waste material by the vibration crusher is evaluated by the content rate of the crushed material having a particle size of less than 5 mm. Specifically, crushing was performed until the ratio of particles having a particle diameter of less than 5 mm reached a set value selected within a range of D to (D + 10) mass%.

  After pulverization by the vibration crusher, the material on the screen is recovered as recycled coarse aggregate and can be reused by sieving with a 5 mm vibrating screen (sieving).

  Fine aggregate can be recovered from the screen underneath of a 5 mm vibrating screen, but if this is the case, the quality requirements for fine aggregate (absolute dry density 2.5 kg / L or more, water absorption 3.0% or less) Have difficulty. That is, as shown in Table 1, about 13 to 22% by mass of cement paste is contained in the under-screen material obtained by sieving the crushed material subjected to crushing and grinding with a vibration crusher with a 5 mm vibration screen. So it is necessary to separate this cement paste.

  In order to separate the cement paste, an air classifying mechanism is provided in the above-described vibratory crusher, and a crushed material (containing a large amount of cement paste) having a particle size of 0.15 mm or less, preferably 0.6 mm or less. Crush while removing by air classification. By doing so, since the cement paste is classified in a stirred and dispersed state, the cement paste can be classified efficiently.

  According to the method for producing a regenerated aggregate of the present invention described above, a processing capacity of 10 ton / h (reproduced coarse aggregate production amount: 4 ton / h) can be obtained with a power of about 90 kW / h, and low energy. Recycled aggregate can be produced at a low cost. Further, the aggregate recovery rate can be secured about 80% or more.

  FIG. 1 is a block diagram showing an embodiment of an aggregate regeneration apparatus for carrying out a method for producing a recycled aggregate according to the present invention.

  The aggregate recycling apparatus shown in FIG. 1 includes a vibratory crusher 1, and a drum-shaped crushing chamber 1a is filled with a rod-shaped crushing medium 2. Although this crushing medium 2 is not clearly shown in the drawing, the crushing medium 2 is composed of two types: a large crushing medium having a rod diameter of 32 mm and a small crushing medium having a rod diameter of 25 mm. : Filled at a ratio of 5 and filled so that the total volume is about 40% of the volume of the crushing chamber 1a.

  The crushing chamber 1a is vibrated by a vibrator (not shown), and a concrete waste input port 1b is provided at the upper end of one end, and coarse particles of the crushed material are discharged at the lower end of the other end. A coarse grain outlet 1c is provided. Further, classification air is introduced from the coarse particle outlet 1c and discharged from the outlet 1d. Fine particles of the crushed material are discharged from the exhaust port 1d together with the classification air. The fine particles are collected by the back filter 3 and discharged as dust from the fine particle discharge port 3a. In the embodiment, the concrete waste material preliminarily crushed to a particle size of 30 mm or less is charged from the charging port 1b, and the fine particles having a particle size of 0.5 mm or less that occupy most of the cement paste are classified and removed by classification air. I did it.

  The coarse particles that are the residue from which the fine particles have been removed are discharged from the coarse particle discharge port 1c, applied to the 25 mm screen 4, and then applied to the 5 mm screen 5, and the material on the 5 mm screen 5 is used as the recycled coarse aggregate. The material below the 5 mm screen 5 is collected as recycled fine aggregate. The coarse particles on the 25 mm screen 4 are returned to the inlet 1b and crushed again.

  FIG.2 and FIG.3 shows the characteristic evaluation result of the reproduction | regeneration coarse aggregate (particle diameter of 25-5 mm) obtained by the vibration type crusher of FIG.

  FIG. 2 shows the relationship between the proportion (mass%) of particles having a particle size of less than 5 mm in the crushed material and the water absorption rate in the pulverized crusher, and FIG. 3 shows the proportion of particles having a particle size of less than 5 mm (mass%) in the crushed material. ) And the absolute dry density.

  The sample 1 shown in FIGS. 2 and 3 is a general concrete waste material, and the sample 2 is a concrete waste material using high-quality aggregate.

  Regarding the water absorption rate, the ratio (3.0% or less) was satisfied by setting the ratio of particles having a particle diameter of less than 5 mm to 56% by mass or more for Sample 1 and 40% by mass or more for Sample 2.

  Regarding the absolute dry density, the ratio of particles having a particle diameter of less than 5 mm was 56% by mass or more for Sample 1 and 40% by mass or more for Sample 1 to satisfy the standard (2.5 kg / L or more).

  As described above, by controlling the degree of crushing using the ratio (mass%) of particles with a particle diameter of less than 5 mm in the crushed material as an index, high-quality regenerated bone that satisfies both the water absorption rate and the absolute dry density of the aggregate The material can be manufactured. Specifically, the proportion of particles having a particle size of less than 5 mm is in the range of mass% (100—rough aggregate content in concrete waste) to {(100—rough aggregate content in concrete waste) +10}. By crushing until the set value selected in (2) is reached, both the water absorption rate and the absolute dry density of the aggregate can be satisfied.

  As an alternative measure, it is conceivable to manage the degree of crushing by directly using the water absorption rate and absolute dry density of the crushed material. In this case, since there is a proportional relationship as shown in FIG. 4 between the water absorption rate and the absolute dry density, the degree of crushing is managed using the absolute dry density as a relatively short measurement time as an index.

  The present invention can be applied to facilities for regenerating and manufacturing coarse aggregates or fine aggregates from concrete waste.

The Example of the aggregate reproduction | regeneration apparatus which enforces the manufacturing method of the reproduction | regeneration aggregate of this invention is shown. The relationship between the ratio of particles having a particle diameter of less than 5 mm in the crushed material and the water absorption is shown. The relationship between the proportion of particles having a particle size of less than 5 mm in the crushed material and the absolute dry density is shown. The relationship between the water absorption rate of aggregate and the absolute dry density is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vibrating crusher 1a Crushing chamber 1b Input port 1c Coarse grain outlet 1d Exhaust port 2 Crushing medium 3 Back filter 3a Fine grain outlet 4 25mm screen (sieving)
5 5mm screen (sieve)

Claims (1)

Concrete waste pre crushed to a particle size 40mm or less, in the manufacturing method of the recycled aggregate for manufacturing recycled aggregate from concrete waste material by crushing the pre-crushed concrete waste by vibrating crusher,
The crushing medium to be filled in the crushing chamber of the vibratory crusher is at least two types of rod-shaped crushing medium having a rod diameter of 50 to 30 mm and rod-shaped crushing medium having a rod diameter of less than 30 to 19 mm. The medium and the small-diameter crushing medium are filled at a volume ratio of 6: 4 to 4: 6, and the crushing medium is filled at a filling rate of 50 to 20% by volume with respect to the volume of the crushing chamber ,
Using this vibratory crusher, the pre-crushed concrete waste material, the proportion of particles having a particle size of less than 5 mm is mass% (100-coarse aggregate content in the concrete waste material) to {(100-in the concrete waste material). Crush until the set value is selected within the range of (crude aggregate content) +10},
In crushing with this vibration type crusher , crushing material with a particle size of 0.15 mm or less is crushed while removing by air classification, and coarse particles with a particle size of 25 mm or more discharged from the vibration type crusher are used. A method for producing recycled aggregate , characterized by crushing again with the vibration crusher .

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