JPH0790208B2 - Asphalt sand preparation method and asphalt sand - 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 preparing sand for asphalt and sand for asphalt, the purpose of which is to debris of concrete produced when a building is demolished and other concrete solidified products to be discarded (hereinafter referred to as concrete). It is called as waste), and asphalt sand generated when roads are rehabilitated can be used to obtain high-quality asphalt sand easily and with good yield. An object of the present invention is to provide a high-quality asphalt sand that does not require a preparation method and a neutralizing agent and can be used for asphalt that is unlikely to deteriorate over time.

[0002]

BACKGROUND OF THE INVENTION Conventionally, concrete and asphalt waste are often landfilled as they are. However, industrial waste such as concrete waste and asphalt waste has become a problem because there is no place to dispose of them in recent years.
Particularly in large cities such as Tokyo and Osaka, landfilling of concrete and asphalt waste and securing land for disposal are becoming increasingly difficult. On the other hand, from the viewpoint of nature conservation and environmental protection, collection of river sand and mountain sand (crushed rocks) is limited, and sand as high-quality fine aggregate is exhausted. The use of sea sand is restricted because the salt content causes concrete deterioration. Therefore, in recent years, it has been attempted to remove foreign matter such as rebar from concrete waste, crush it to 40 mm or less, and use it as crushed stone to be laid on the foundation of a road or the like.

[0003]

2. Description of the Related Art In general, waste concrete materials contain metal such as rebar and gravel, sand and cement are mixed as concrete mixing materials. Among them, the cement content is originally strongly alkaline and reacts with rainwater during grinding to form calcium carbonate, and the alkalinity may be strong, so when normally crushed and used as fine aggregate. It is prepared by washing away the alkali and dust by washing with water. As described above, the wet process of the crushing process has another purpose of preventing dust pollution during the work. However, the fine aggregate prepared by the wet method has a water content of 20% or more, and it is dried in the open-air for 14 to 15 minutes.
However, there is a problem of secondary pollution treatment such as sludge treatment.

On the other hand, in Japanese Unexamined Patent Publication No. Sho 61-61878, a large block concrete block containing reinforcing bars and steel frames generated when a concrete structure is dismantled is crushed by a crushing machine of a crushing method such as a jaw crusher and the reinforcing bars and steel frames are Waste concrete which is separated and removed to form medium-sized concrete, then the medium-sized concrete is impact-crushed by an impact-type crusher such as an inverter breaker, and then the destroyed concrete components are sorted according to the required grain size and reused. Is disclosed.

[0005]

The above disclosed technique is an excellent technique for recovering high quality aggregates mixed with concrete from waste concrete for resource saving. There is a problem that the fine aggregate obtained by the above is not sufficient to be used as a fine aggregate for asphalt. That is, since concrete showing a strong alkalinity is contained in the waste concrete, when such fine aggregate is used as the asphalt aggregate, the asphalt pitch and the fine aggregate are There has been a problem that a chemical reaction occurs with the aggregate and the strength of the asphalt becomes weaker over time. In addition, in concrete waste materials, calcium carbonate may have been formed by the reaction with rainwater, and even fine aggregate collected by crushing such waste materials may cause cracks in the asphalt after construction. However, there was a problem that asphalt with excellent strength could not be constructed.

On the other hand, in view of the above-mentioned circumstances, there has been a trial example in which fine aggregate collected by using waste asphalt as a raw material is not used as fine aggregate for asphalt. However, there is a problem in that even aggregates obtained by crushing and destroying asphalt waste materials and sorting them according to the required particle size do not result in high-quality fine aggregate for asphalt. That is, asphalt is usually composed of about 60% crushed stone, 30% sand, and 6% pitch, and the asphalt waste material has substantially the same composition. When an asphalt waste material having such a composition is pulverized and classified, a pitch thin film is always coated on the surface of the obtained fine aggregate. However, when such fine aggregate is used as an asphalt aggregate, the acidity becomes too strong due to the pitch thin film contained in the waste material,
There was a problem that the constructed asphalt was prone to deterioration over time. Furthermore, it is necessary to perform peeling polishing to remove the pitch coating from the surface of the pulverized material of the asphalt waste material, and there is a problem that it cannot be used in general because of the increased number of steps,
There was a problem of wastewater treatment during peeling and polishing.

Therefore, the present invention effectively reuses a large amount of asphalt waste generated by road rehabilitation and the like together with concrete waste materials, prepares high-quality asphalt sand from these wastes easily and with good yield, and effectively uses resources. The purpose of the present invention is to provide a preparation method capable of achieving the protection of nature and a high quality asphalt sand recovered from existing concrete waste or asphalt waste.

[0008]

The present invention has been made to solve the above problems. In the method for preparing asphalt sand according to claim 1, foreign matter such as rebar is removed.
Mixture of concrete waste with water content of 20% or less crushed to mm or less and asphalt waste is used as a raw material, and this raw material is sequentially supplied to a crushing step and a classification step, and 0 to 4 mm
The sand content is collected as fine aggregate, and the object to be crushed exceeding 4 mm is supplied again to the crushing step, while the dust such as cement and fine powder generated during the crushing step and the classifying step is collected. Then, the dust and the fine aggregate were mixed to obtain sand for asphalt, and all of these operations were performed dry. The asphalt sand according to claim 2, which is the asphalt sand recovered from a mixture of concrete waste and asphalt waste crushed to 20 mm or less by removing foreign substances such as reinforcing bars, and the asphalt sand is the mixture. 85 obtained by crushing
% Or more of 0.074 to 4 mm of fine aggregate, and 15% or less of 0.074 mm generated at the time of pulverizing and classifying the mixture.
It is assumed that the mixture is made of the following fine powder and dust such as cement, and the water content is 9% or less.

[0009]

The method for preparing sand for asphalt and the structure of the sand for asphalt according to the present invention will be specifically described below with reference to the drawings. 1 and 2 show one embodiment of a method for preparing asphalt sand according to the present invention. In the present invention, as the raw material 10, a mixture of concrete waste and asphalt waste from which foreign substances such as reinforcing bars have been removed by an existing processing apparatus and which has been ground to 20 mm or less is used. In the present invention, the mixture of concrete waste and asphalt waste is used as the raw material 10 because the acidic state exhibited by the pitch component present in the asphalt waste is contained in the concrete waste as described later. This is because it is possible to obtain a high-quality asphalt sand that is neutralized by the cement content and calcium carbonate, etc., and does not easily deteriorate over time. The raw material 10 is stored in the hopper 1. A cutting facility 2 is provided at the lower end discharge port of the hopper 1. As the cutting equipment 2, for example, a vibrating feeder is used, and the raw material 10 is continuously cut out by a predetermined amount and supplied to the crushing device 4 via the conveying device 3. As the transport device 3, any device such as a belt conveyor is used.

The crushing device 4 is for further crushing the raw material 10 into fine particles of 0 to 4 mm, and various crushing, grinding or crushing devices can be used. In this embodiment, a super sander (trade name) is used. There is. The material to be crushed generated by crushing the raw material 10 is sand having a cement content or a fine powder content attached thereto, and further, a sand content having a pitch attached thereto. Crusher 4
The material to be crushed from the crusher is then sieved by a classifying device 5, and if it exceeds 4 mm, it is returned to the crushing device 4 via the conveying device 3. As the classifying device 5, an ordinary dry type device is preferable. On the other hand, 0 to the ones screened by the classifier 5
4 mm of sand is collected as fine aggregate 11.

Further, the dust such as cement and fine powder generated during the crushing process and the classification process is sent to the dust collector 6 and collected. As the dust collector 6, for example, a dry type device such as an electric dust collector or a bag filter can be arbitrarily used. The dust 13 collected by the dust collector 6 and the fine aggregate 11 that has been sieved and collected by the classifier 5 are mixed to form a product (sand for asphalt) 12. This product 12 is 0-4m /
m sand, mud 11 and a mixture of dust 13 such as cement of 0.07 mm or less, which is alkaline and has a water content of 9%.
It is the following.

In the present invention, it is not necessary to completely and concretely collect concrete waste and asphalt waste at the collection site. The reason is that the fine aggregate prepared from asphalt waste has a coating of pitch adhered thereto, but since it is used again as fine aggregate for asphalt, it is not necessary to remove the pitch. In addition, concrete waste and asphalt waste are heavy in the waste collection site, and separation of them is difficult and impractical even if they are completely stored.

Generally, the compounding ingredients that constitute asphalt are strongly acidic (due to the sulfur content in the pitch). However, when cement dust, calcium carbonate or the like (dust 13) is mixed with the pulverized product (fine aggregate 11) obtained from the mixture of asphalt waste and concrete waste as in the present invention, the acidity due to pitch is neutralized. In addition, this neutralization causes the crushed product of asphalt waste and the crushed product of concrete waste to react favorably, is less likely to deteriorate over time, and is desirable because it is possible to construct high-strength asphalt. Since the dust 13 to be discarded can be used, the yield is also desirable.

The sand for asphalt according to the present invention obtained by such a preparation method has a water content of 9% or less and a sand content of 0.074 to 4 mm is 85% or more by dry preparation.
15% or less of dust of 0.074 mm or less is included.
A water content of 9% or less is prepared at least 0-2.
This is because the raw material having a water content of 20% or less of the concrete waste and the asphalt waste prepared in advance to 0 mm is used, and all the steps are performed by a dry method. Since the water content is 9% or less, the heating temperature when asphalt is prepared by mixing and heating pitch, sand, and crushed stone can be kept low. Excellent in terms of workability. Incidentally, the normal fine aggregate is 14 to 2
It is 0%. This normal water content is the limit of the Amano stack drying method.

In the asphalt sand according to the present invention, it is an average experimentally known value of the inventor that the sand content is 85% or more and the mud and cement contents are 15% or less.

[0016]

As described above in detail, according to the present invention, a mixture of concrete waste having a water content of 20% or less and asphalt waste, which is obtained by removing foreign matters such as rebar and crushed to 20 mm or less, is used as a raw material. It is supplied to the crushing step and the classifying step to recover the sand content of 0 to 4 mm as fine aggregate, and the object to be crushed exceeding 4 mm is again supplied to the crushing step, while it is generated during the crushing step and the classifying step. Dust such as cement content or fine powder is collected by a dust collector, and the dust and the fine aggregate are mixed to obtain sand for asphalt, and asphalt sand characterized by performing all of these operations in a dry process. Since it is a method of preparation, the use of concrete waste or asphalt waste, for which it is difficult to secure the disposal site, does not require a neutralizing agent and is applied with high-strength asphalt. It asphalt sand quality can be prepared easily and with good yield which can be, an excellent effect that it is possible to achieve an effective use of resources and conservation. Furthermore, the present invention is an asphalt sand recovered from a mixture of concrete waste and asphalt waste crushed to 20 mm or less by removing foreign matter such as rebar, and the asphalt sand is obtained by crushing the mixture. 85% or more of 0.074 to 4 mm fine aggregate and 15 generated during pulverization and classification of the mixture
% Of 0.074 mm or less of fine powder, a mixture of dust such as cement, and a water content of 9% or less, the sand for asphalt is characterized by the need for a neutralizing agent. It has an excellent effect that it is a high-quality asphalt sand capable of constructing asphalt that does not have to be treated, has high strength, and is resistant to deterioration over time.

[Brief description of drawings]

FIG. 1 is a flow sheet of an example of a method for preparing sand for asphalt from concrete and asphalt waste according to the present invention.

FIG. 2 is a flow sheet similar to FIG.

[Explanation of symbols]

 1 Hopper 2 Cutting Equipment 3 Conveying Device 4 Crushing Device 5 Classifying Device 6 Dust Collection Device 10 Raw Material 11 Sand Content 12 Product 13 Dust

Claims (2)

[Claims] 1. Breaking down to less than 20 mm by removing foreign matter such as rebar
Crushed concrete waste and asphalt with water content below 20%
The raw material is a mixture with quart waste, and this raw material is sequentially powdered.
Supply to the crushing process and classification process to finely sand the 0-4 mm sand
The material to be crushed that exceeds 4 mm
Supply again to the crushing process, while crushing process and classifier
Dust collector for dust such as cement and fine powder generated during the process
And collect the dust by mixing with the fine aggregate.
Get the sand for the asphalt, and do all of this work dry.
A method for preparing sand for asphalt, which comprises performing. 2. Removing foreign matter such as rebar and breaking to less than 20 mm
Crushed concrete waste and asphalt waste
An asphalt sand recovered from the mixture,
This asphalt sand is obtained by crushing the mixture
85% or more of 0.074 to 4 mm fine aggregate and the above mixture
15% or less of 0.074 generated when crushing and classifying objects
From a mixture of fine powder of less than mm and dust such as cement
And its water content is less than 9%.
Sand for asphalt to collect .