Alternate aggregate for asphalt mixture, and asphalt mixture

Abstract

To provide an alternative aggregate which is a recycled product of an aggregate contained in an asphalt mixture or a concrete composition and can be used as a substitute for virgin aggregate in the asphalt mixture, and to provide an asphalt mixture containing the alternative aggregate.SOLUTION: The present invention provides an alternative aggregate for asphalt mixture having an asphalt adhesion amount of more than 0 mass% and 1.5 mass% or less, and an asphalt mixture comprising the alternative aggregate for asphalt mixture, an aggregate for asphalt mixture (excluding the alternative aggregate for asphalt mixture), asphalt, and a filler.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an alternative aggregate for asphalt mixtures, and an asphalt mixture. [Background technology]

[0002] Asphalt pavement using asphalt mixture is generally used for paving roads, sidewalks, etc. Asphalt pavement is a base layer and a surface layer formed of asphalt mixture on a roadbed material. The asphalt mixture contains asphalt, granular aggregate, filler, etc. Asphalt pavement has a road surface formed of asphalt mixture in which aggregate is bound with asphalt, so that the paved road has sufficient hardness and durability.

[0003] Conventionally, recycled aggregate obtained by crushing waste asphalt mixtures used in asphalt pavement has been used. The recycled aggregate has deteriorated and hardened asphalt attached to it, and the asphalt may have adverse effects, so it is not suitable to use the recycled aggregate alone. Therefore, it is common to mix the recycled aggregate with virgin aggregate for use (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-35740 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, recycled aggregate cannot be used in high proportions due to the standards for asphalt mixtures. Specifically, the mixing ratio of recycled aggregate is limited to about 50 mass%, and the recycling efficiency cannot be said to be high.

[0006] On the other hand, aggregates are also used in concrete used for buildings and road paving. Mortar is attached to the aggregates in such concrete compositions, but it would be useful if the mortar could be removed and used as an alternative aggregate for asphalt mixtures.

[0007] The present invention has been made in consideration of the above-mentioned problems in the conventional art, and an object of the present invention is to provide an alternative aggregate which is a recycled product of aggregate contained in an asphalt mixture or a concrete composition and can also be used as a virgin aggregate in an asphalt mixture, and an asphalt mixture containing the alternative aggregate. [Means for solving the problem]

[0008] One aspect of the present invention that solves the above problems is as follows. (1) An alternative aggregate for asphalt mixtures having an asphalt adhesion amount exceeding 0% by mass and not exceeding 1.5% by mass.

[0009] (2) An alternative aggregate for asphalt mixtures having a wear loss of 30% by mass or less.

[0010] (3) An asphalt mixture comprising at least one of the alternative aggregate for asphalt mixtures described in (1) above and the alternative aggregate for asphalt mixtures described in (2) above, at least one of aggregate for asphalt mixtures (excluding the alternative aggregate for asphalt mixtures) and recycled aggregate for asphalt, asphalt, and a filler. Effect of the Invention

[0011] According to the present invention, it is possible to provide an alternative aggregate that is a recycled product of aggregate contained in an asphalt mixture or concrete composition and can also be used as a virgin aggregate in an asphalt mixture, and an asphalt mixture containing the alternative aggregate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <Alternative aggregate for asphalt mixture> The alternative aggregate for asphalt mixture of this embodiment has two forms, a first form and a second form, and the first form is characterized in that the amount of asphalt adhesion is more than 0 mass% and 1.5 mass% or less. The second form is characterized in that the mortar is removed and the amount of wear loss is 30 mass% or less. The first form of the alternative aggregate for asphalt mixture is derived from aggregate in the asphalt mixture, and the second form of the alternative aggregate for asphalt mixture is derived from aggregate in the concrete composition. In the first embodiment, the amount of asphalt attached is very small compared to the recycled aggregate. In the second embodiment, the amount of wear loss is 30% by mass or less, which indicates that a certain amount of mortar has been removed, that is, the amount of mortar attached is very small compared to the recycled aggregate. Therefore, in either embodiment, even if the alternative aggregate for asphalt mixture of this embodiment is used in an asphalt mixture at a higher ratio than before, problems caused by asphalt or mortar attached to the aggregate are unlikely to occur. Therefore, the alternative aggregate for asphalt mixture of this embodiment can be substituted for virgin aggregate in asphalt mixtures, and recycling efficiency can be improved. In addition, in the case of recycled aggregate, the amount of use is limited due to the specifications of the recycled aggregate or the influence of the properties of deteriorated old asphalt, but the alternative aggregate for asphalt mixture of this embodiment, which can be substituted for virgin aggregate, can increase the amount of recycled aggregate used by replacing the alternative aggregate for asphalt mixture, whose raw material is recycled aggregate, with virgin aggregate in addition to the amount of conventional recycled aggregate used. The alternative aggregate for asphalt mixtures of the present embodiment is neither a virgin aggregate nor a recycled aggregate, but a new category of aggregate. The first and second types of substitute aggregate for asphalt mixture will be described below.

[0013] 《First form》 As described above, the first type of substitute aggregate for asphalt mixtures has an amount of adhered asphalt that is more than 0 mass % and 1.5 mass % or less. The first type of substitute aggregate for asphalt mixture is obtained by grinding the asphalt mixture obtained by recovering asphalt pavement, and was originally used as an aggregate in asphalt mixture. The aggregate in question includes coarse aggregate with a particle size of 2.36 mm or more and fine aggregate with a particle size of less than 2.36 mm. Coarse aggregate is aggregate that is retained on a 2.36 mm sieve. Fine aggregate is aggregate that passes through a 2.36 mm sieve and is retained on a 0.075 mm sieve. Examples of coarse aggregate include No. 7 crushed stone with a particle size of 2.36 mm or more and less than 4.75 mm, No. 6 crushed stone with a particle size of 4.75 mm or more and less than 13.2 mm, No. 5 crushed stone with a particle size of 13.2 mm or more and less than 19 mm, and No. 4 crushed stone with a particle size range of 19 mm or more and less than 31.5 mm. The fine aggregate has a particle size of 0.075 mm or more and less than 2.36 mm. Examples of the fine aggregate include river sand, dune sand, mountain sand, sea sand, coarse sand, crushed sand, fine sand, screenings, crushed stone dust, silica sand, artificial sand, glass cullet, foundry sand, and recycled crushed aggregate sand.

[0014] 《Second form》 On the other hand, the second type of substitute aggregate for asphalt mixture has the mortar removed and the abrasion loss is 30 mass% or less as described above. The abrasion loss can be obtained by measuring according to the JIS A 1121 standard. The second type of substitute aggregate for asphalt mixture is obtained by grinding a concrete composition obtained by recovering used concrete, and is originally used as an aggregate in a concrete composition. The aggregate in question can be a coarse aggregate. Examples of the coarse aggregate include river gravel, sea gravel, mountain gravel, crushed stone, slag crushed stone, etc. These can be used alone or in combination. Coarse aggregates specified in JIS A 5005 can also be used.

[0015] The asphalt mixture substitute aggregate of this embodiment can be manufactured, for example, as follows, in both the first and second forms. That is, a dust collector is attached to a dry rotor mill, and fine powder generated by grinding the used asphalt mixture or concrete composition is collected by the dust collector while grinding the aggregate to be recycled. According to this manufacturing method, by grinding the aggregate with the rotor mill, the asphalt or mortar attached to the aggregate is peeled off and turned into fine powder, and the fine powder is collected by the dust collector. Therefore, in the first form, asphalt does not adhere to the aggregate again, so that the amount of asphalt attached within the above numerical range can be realized. In addition, in the second form, mortar does not adhere to the aggregate again, so that the wear loss of 30 mass% or less can be realized by removing the weak mortar.

[0016] The alternative aggregate for asphalt mixture of the present embodiment is used as an aggregate for asphalt mixture as its name suggests. Such an asphalt mixture will be described below.

[0017] <Asphalt mixture> The asphalt mixture of this embodiment is characterized by containing at least one of the first type alternative aggregate for asphalt mixtures and the second type alternative aggregate for asphalt mixtures described above, at least one of aggregate for asphalt mixtures (excluding alternative aggregate for asphalt mixtures) and recycled aggregate for asphalt, asphalt, and a filler.

[0018] [Alternative aggregate for asphalt mixtures] The alternative aggregate for asphalt mixture is at least one of the above-mentioned first type alternative aggregate for asphalt mixture and the second type alternative aggregate for asphalt mixture. That is, the first type and the second type alternative aggregate for asphalt mixture may be used alone or in combination. The above explanations are applicable to the first type and the second type alternative aggregate for asphalt mixture.

[0019] On the other hand, the asphalt mixture of this embodiment includes at least one of aggregate for asphalt mixture (excluding alternative aggregate for asphalt mixture) and recycled aggregate for asphalt, in addition to the alternative aggregate for asphalt mixture. That is, aggregate for asphalt mixture and recycled aggregate for asphalt may be used alone, or both may be used in combination. However, when recycled aggregate for asphalt is used, the content of recycled aggregate in the standard for asphalt mixture is followed. That is, the standard for asphalt mixture specifies the upper limit of the amount of recycled aggregate to be used, and the recycled aggregate for asphalt can be used in the asphalt mixture of this embodiment within the range below the upper limit. The aggregate for asphalt mixture and recycled aggregate for asphalt are described below.

[0020] [Aggregate for asphalt mixtures] Aggregates for asphalt mixtures are virgin aggregates, not recycled aggregates. In other words, the portion that is insufficient in the alternative aggregates or recycled aggregates mentioned above is supplemented with aggregates for asphalt mixtures of the same classification as the recycled aggregates. For example, when using No. 6 crushed stone as aggregate, alternative aggregates and / or recycled aggregate No. 6 crushed stone is mixed with new No. 6 crushed stone. In addition, the aggregate for asphalt mixture is different from the recycled aggregate for asphalt mixture in whether it is virgin or used, and whether it has asphalt attached or not, but the material itself is equivalent. Therefore, the above-mentioned examples of recycled aggregate for asphalt mixture apply as it is.

[0021] [Recycled aggregate for asphalt mixtures] The recycled aggregate for asphalt mixture, like the alternative aggregate for asphalt mixture of this embodiment, is obtained by crushing the asphalt mixture obtained by recovering asphalt pavement, and was originally used as an aggregate in asphalt mixture. That is, the recycled aggregate for asphalt mixture is different from the alternative aggregate for asphalt mixture of this embodiment in the amount of asphalt attached, but the other forms are the same. The amount of asphalt attached in the alternative aggregate for asphalt mixture of this embodiment is more than 0 mass% and 1.5 mass% or less, while the amount of asphalt attached in the recycled aggregate for asphalt mixture is 3.8 mass% or more.

[0022] As the aggregate in the asphalt mixture of this embodiment, the mixing ratio of the alternative aggregate for asphalt mixtures among the aggregates of the same classification can be increased. Specifically, the mixing ratio of the alternative aggregate for asphalt mixtures can be 1 to 99 mass%.

[0023] [asphalt] Asphalt is a polymeric material produced from petroleum. It is liquid at high temperatures, but its viscosity increases as the temperature drops. Various types of asphalt can be used. For example, in addition to straight asphalt, which is petroleum asphalt for paving, modified asphalt can be used. Modified asphalt can be blown asphalt, which is modified with polymers (polymeric materials) such as thermoplastic elastomers and thermoplastic resins. Straight asphalt is the residual bitumen material obtained by subjecting crude oil to atmospheric distillation equipment, reduced pressure distillation equipment, etc. Blown asphalt refers to asphalt obtained by heating straight asphalt and then blowing air into it to oxidize it.

[0024] [Filler] In this embodiment, the filler may be stone powder, slaked lime, cement, recovered dust, fly ash, or the like.

[0025] The content of aggregate and filler in the asphalt mixture is preferably 90 to 97 mass%, more preferably 93 to 97 mass% in general regions, and even more preferably 90 to 95 mass% in snowy and cold regions.

[0026] The asphalt mixture of this embodiment can be produced in the same manner as the production of a normal asphalt mixture. For example, it can be obtained by mixing heated aggregate (alternative aggregate for asphalt mixture of this embodiment), filler, and asphalt by a standard method. The heated aggregate, filler, and asphalt can be mixed simultaneously or in any order.

Claims

1. An alternative aggregate for asphalt mixtures, having an adhesion amount of asphalt greater than 0% by mass and not more than 1.5% by mass.

2. An alternative aggregate for asphalt mixtures, having an abrasion loss of 30% by mass or less.

3. An asphalt mixture comprising at least one of the alternative aggregate for asphalt mixtures according to claim 1 and the alternative aggregate for asphalt mixtures according to claim 2, at least one of aggregate for asphalt mixtures (excluding the alternative aggregate for asphalt mixtures) and recycled aggregate for asphalt, asphalt, and a filler.