JP2890187B2 - Manufacturing method of super high quality recycled aggregate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing recycled aggregate for recovering aggregate from waste concrete generated when a concrete structure is dismantled.

[0002]

2. Description of the Related Art Conventionally, as a method for producing recycled aggregates for recovering aggregate particles from concrete waste generated due to demolition of concrete structures, etc., a method for producing recycled aggregates is to simply crush concrete waste with a crusher or the like and screen it with a screen. Thus, coarse and fine aggregate particles are taken out from the waste concrete, and the extracted coarse and fine aggregate particles are used as recycled aggregate.

[0003]

However, in the recycled aggregate obtained by simply crushing and sieving the waste concrete, the mortar component adheres to the surface of the aggregate particles, and this is not sufficiently removed. Therefore, the water absorption rate is higher than the original aggregate, and when it is used as it is as concrete, the unit water volume increases and the hardened concrete has low strength and a large drying shrinkage. is there. Therefore, even if such recycled aggregate is used as concrete, it is used only for discarded concrete at best.

In view of the above points, the present inventors have conducted intensive studies and as a result, have found that a recycled aggregate having a low water absorption and comparable to ordinary aggregate can be obtained, and completed the present invention.

[0005]

Means for Solving the Problems The recycled aggregate according to the present invention is obtained by crushing waste concrete, extracting coarse and fine aggregate particles from the waste by sieving, and then adding ultra-high pressure jet water to the aggregate. Is sprayed to remove mortar or cement paste from the surface of coarse and fine aggregate particles to obtain a recycled aggregate.

Hereinafter, the present invention will be described in detail. Concrete waste refers to concrete waste generated by demolition of concrete structures. In order to obtain the recycled aggregate according to the present invention from the concrete waste material, it is first roughly ground to about 500 mm square by a hydraulic breaker or the like, and grinds are used to remove soil and other impurities attached to the concrete block. Thereafter, the concrete mass is divided into small pieces using a jaw crusher or the like, and the reinforcing bar and the concrete are separated, and the separated reinforcing bar is removed by a magnetic separator. After removal, crush it with an impact crusher.
The grains are separated into grains of about 0 mm, grains of about 40 to 5 mm and grains of 40 mm or more. The grains of 40 mm or more are returned again to the impact crusher to obtain grains of 5 to 0 mm and grains of 40 to 5 mm. The grains of 40 to 5 mm correspond to recycled coarse aggregates, and the grains of 5 to 0 mm correspond to recycled fine aggregates. By the way, the mortar adhesion rate of the recycled coarse aggregate at this stage can be considered to be about 40% or more. The cement paste adhesion rate of the recycled fine aggregate is approximately 20%.
% Can be seen. The recycled aggregate thus obtained is applied to an aggregate rubbing machine typified by a cone crusher to make grains of 30 to 25 mm or less. The mortar adhesion rate of the recycled coarse aggregate at this stage is about 30%. The cement paste adhesion rate of the recycled fine aggregate thus obtained is about 20%. And
In the final stage of the regenerated coarse / fine aggregate in these steps, ultra-high pressure jet water is injected. The mortar adhesion rate of the recycled coarse aggregate in this final stage is 5% or less. The cement paste adhesion rate of the recycled fine aggregate at this stage is 10% or less. By the way, the conditions of the ultra-high pressure jet water injection are as follows, but the injection pressure at which the mortar or cement paste is sufficiently peeled off from the aggregate surface without crushing the aggregate is 1,000 to 2,800K.
It is preferable to determine the value based on gf / cm ² . In addition, since such ultra-high pressure jet water is required to sufficiently exhibit its jetting ability, when crushing concrete waste material, in addition to primary crushing by jaw crusher etc. in coarse crushing, then secondary crushing by impact crusher etc., and If necessary, it is preferable to set the mortar or cement paste adhesion rate to 35% or less by applying an aggregate rubbing machine using a cone crusher or the like. Here, it is preferable that the recycled aggregate be rotated and moved using a trommel or the like in order to improve the injection efficiency when the ultra-high pressure jet water is injected.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples,
Various modifications are possible.

[0008]

EXAMPLE Concrete waste was first subjected to an impact crusher as a secondary crusher to obtain a regenerated coarse aggregate having a particle size of 40 to 5 mm and a regenerated fine aggregate having a particle size of 5 to 0 mm. Table 1 shows the results. At this stage, the mortar adhesion of the recycled coarse aggregate was 48.2%, and the cement paste adhesion of the recycled fine aggregate was 25.8%. This product is further crushed by a cone crusher, an aggregate rubbing machine, to reduce the particle size to 30.
Regenerated coarse and fine aggregates having a size of 25 mm or less were obtained. Table 1 shows the results. Here, the mortar adhesion of the recycled coarse aggregate was 31.1%, and the cement paste adhesion of the recycled fine aggregate was 21.0%. According to this, it can be seen that the recycled aggregate of the prior art has a very high mortar or cement paste adhesion amount. Based on these facts, in the present invention, an injection test using ultra-high pressure jet water was performed under the experimental conditions shown in Table 2 using recycled coarse and fine aggregates obtained with an impact crusher or a cone crusher. Table 2 shows the results. According to this, although only the impact crusher was used, the mortar adhesion rate of the recycled coarse aggregate was 5.0%, and the cement paste adhesion rate of the recycled fine aggregate was 9.7%. The mortar adhesion rate of the recycled coarse aggregate was 1.8% and the cement paste adhesion rate of the recycled fine aggregate was 4.6% (injection time was 2 minutes). thing). According to this, it can be seen that the product according to the present invention is superior in that the mortar or cement paste adhesion rate is lower than that according to the prior art. Among them, those using the cone crusher in addition to the impact crusher have a particularly low adhesion rate of mortar or cement paste and are excellent. By the way, in the ultrahigh-pressure jet water injection test, an ultrahigh-pressure jet water injection test machine based on mechanical specifications (Table 3) manufactured by FLOW-JAPAN was used. Table 4 shows the quality of the recycled aggregate (draft) in relation to the effect according to the present invention, and Table 5 shows the result of the use of the concrete using the recycled aggregate.

As a result, the recycled aggregate according to the prior art (Table 1)
Quality criteria for recycled aggregate (draft) based on 1) (Table 4)
In the light of the use types of recycled aggregate (Table 5), the quality standards (draft) for recycled coarse aggregates are in relation to the quality standards (draft) for recycled aggregate. Only slightly enters the three loosest types of recycled coarse aggregate. Similarly, the recycled fine aggregate also barely enters the two loosest types of recycled fine aggregate of the recycled aggregate quality standard (draft). Can be said to be something. In addition, it can be understood that the recycled coarse aggregate and the recycled fine aggregate are only used as discarded concrete and the like in relation to the usage of the recycled aggregate concrete. On the other hand, the recycled aggregate (Table 2) according to the present invention corresponds to one of the quality standards (draft) of the recycled aggregate, and is found to be used for reinforced concrete, unreinforced concrete, and the like. .

[0010]

According to the method for manufacturing an ultra-high-quality recycled aggregate according to the present invention described in detail above, the mortar or cement paste is removed from the surface of the recycled aggregate in a short time and almost completely. Therefore, the water absorption of the recycled aggregate caused by the adhesion of the mortar or the cement paste can be greatly reduced, and the stability of the aggregate can be greatly improved. For this reason, when the recycled aggregate according to the present invention is used to make a concrete structure, it has the effect of obtaining a material having the same high strength as that of a normal aggregate.

[Table-1]

[Table-2]

[Table-3]

[Table-4]

[Table-5]

Claims (2)

(57) [Claims] Crushing concrete waste generated during the dismantling of a cement concrete structure, crushing and sieving to remove coarse and fine aggregate particles from the waste material, and then spraying ultra-high pressure jet water onto the coarse and fine A method for producing ultra-high-quality recycled aggregate, characterized by removing mortar or cement paste from the surface of aggregate particles. 2. The method according to claim 1, wherein when the concrete waste is crushed, it is subjected to a secondary crushing by an impact crusher or the like, and then to an aggregate rubbing machine by a cone crusher or the like, if necessary, in addition to the primary crushing by a jaw crusher or the like. 2. The method for producing ultra-high-quality recycled aggregate according to item 1.