JP2014025259A - Asphalt mixture with high flexibility and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an asphalt mixture that has high flexibility, vibration damping properties and crack resistance, and simultaneously has plastic deformation resistance that is an opposite property of these properties, can be produced in a usual asphalt mixture factory, and also can show excellent workability when being constructed by using a usual construction machine.SOLUTION: The asphalt mixture contains: an aggregate; polymer-modified asphalt in which asphalt is dispersed in a polymer to form a polymer continuous phase; and a mineral oil having a fluid point of -10°C or lower. The mineral oil in an amount of 10 wt.% to 30 wt.% is contained with respect to the polymer-modified asphalt.

Description

  The present invention relates to an asphalt mixture and a method for producing the same, and more particularly to an asphalt mixture having high flexibility, vibration damping, crack resistance, and plastic deformation resistance, and a method for producing the same.

  The following materials have been proposed as materials with high flexibility used for asphalt pavement.

  Patent Document 1 discloses a pavement in which rubber chips and asphalt mortar are mixed.

  Patent Document 2 discloses an elastic pavement mixture in which asphalt, thermoplastic elastomer, stone powder, and aggregate are mixed.

  Patent Document 3 discloses an asphalt mixed object obtained by mixing an asphalt composition containing asphalt, a thermoplastic elastomer, process oil, and a ductile material, and an aggregate.

  Patent Documents 4 and 5 show asphalt compositions comprising asphalt, rubber and / or thermoplastic elastomer, mineral oil, and low molecular weight polyethylene or a phenyl ether compound having a specific substituent.

JP 2006-183271 A JP 2000-204262 A JP-A-2005-200355 JP 2003-3070 A JP 2003-192901 A

  Patent Document 1 has a problem that it is inferior in durability, such as scattering of rubber chips, because it is a pavement with many voids in which a single particle size rubber chip is bonded with asphalt mortar.

  Patent Document 2 has a problem that the viscosity of the asphalt mixture becomes high and the workability is poor because a large amount of a styrene thermoplastic elastomer that melts at 80 to 120 ° C. is blended.

  With respect to Patent Document 3, a special asphalt composition obtained by mixing asphalt, a thermoplastic elastomer, process oil, and a ductile material is used. Therefore, when producing an asphalt mixture, a dedicated asphalt composition for heating and storing is used. There has been a problem in that an asphalt tank or a special asphalt lorry vehicle for heating the asphalt composition and transferring it to the asphalt pipe of the asphalt mixture factory is required.

  Patent Documents 4 and 5 are both intended to improve mixing properties and storage stability, and require low-molecular-weight polyethylene or phenyl ether compounds having specific substituents, and have a low mineral oil content. Therefore, even if an asphalt mixture is produced using this as a binder, high flexibility, vibration damping, crack resistance, and plastic deformation resistance cannot be exhibited in a balanced manner.

  In other words, even a highly flexible asphalt mixture can be easily manufactured at a normal asphalt mixture factory, good workability can be obtained with normal construction machines, and it can withstand long-term use after construction. It is desirable that

  Furthermore, as a basic property of the highly flexible asphalt mixture, it is desirable that the high flexibility, vibration damping property, crack resistance, and plastic deformation resistance can be exhibited in a balanced manner.

  The present invention has been made in view of such problems, and its object is to have high flexibility, vibration damping, and crack resistance, as well as plastic deformation resistance, which is a contradictory property to these. And providing an asphalt mixture that can be produced in an ordinary asphalt compound factory and that can be obtained with a normal construction machine.

  In order to achieve the above object, a highly flexible asphalt mixture according to the present invention includes an aggregate, a polymer-modified asphalt in which asphalt is dispersed in a polymer to form a polymer continuous phase, and a pour point is − It contains a mineral oil of 10 ° C. or less, and the mineral oil is contained in an amount of 10 wt% to 30 wt% with respect to the polymer-modified asphalt.

  Further, in the method for producing a highly flexible asphalt mixture of the present invention, when producing the above highly flexible asphalt mixture, the asphalt is contained in an aggregate heated to 150 to 220 ° C and a polymer heated to 150 to 200 ° C. It is characterized in that it is mixed with polymer-modified asphalt in which a dispersed polymer continuous phase is formed, and mineral oil having a pour point of −10 ° C. or less is added and mixed therewith.

  Further, in the method for producing a highly flexible asphalt mixture of the present invention, when producing the above highly flexible asphalt mixture, the asphalt is dispersed in a polymer heated in advance at 150 to 200 ° C. to form a polymer continuous phase. The polymer-modified asphalt is mixed with mineral oil having a pour point of −10 ° C. or less, and then mixed with the aggregate heated to 150 to 220 ° C.

  Since the highly flexible asphalt mixture of the present invention uses polymer-modified asphalt as a raw material, it can be easily manufactured in a normal asphalt mixture factory, and good workability can be obtained with a normal construction machine. .

  And, when the highly flexible asphalt mixture of the present invention is used for the surface layer, the highly flexible asphalt mixture of the present invention has high flexibility at low temperature, so that snow and rain etc. are frozen and an ice plate is formed on the surface layer. Even if formed, the surface layer partially bends due to the load of the passing vehicle, so that the ice plate is broken and broken, so that an ice burn is not formed on the surface layer. In addition, since the highly flexible asphalt mixture of the present invention has vibration damping properties, it has the effect of dampening vibrations generated by a passing vehicle and reducing vibrations propagating along the road.

  On the other hand, when the highly flexible asphalt mixture of the present invention is used for the base layer, since the highly flexible asphalt mixture of the present invention has a vibration damping property, the base layer attenuates the vibration generated on the surface layer by a passing vehicle, It has the effect of reducing vibrations propagating along the road. Moreover, since the highly flexible asphalt mixture of this invention has high crack resistance, even if the crack has generate | occur | produced in the layer of the lower surface of a base layer, there exists an effect which can suppress generating a crack in a base layer and a surface layer.

It is a graph which shows the measurement result of a loss factor. It is a graph which shows the addition amount of mineral oil, and the relationship of HIC. It is a graph which shows the relationship between the addition amount of mineral oil, and dynamic stability. It is a graph which shows the relationship between the pour point of mineral oil, and HIC. It is a graph which shows the relationship between the pour point of mineral oil, and a fracture | rupture strain.

  Hereinafter, the polymer-modified asphalt, mineral oil and aggregate used in the present invention will be described, and then the production method will be described.

[Polymer modified asphalt]
The polymer-modified asphalt used in the present invention is obtained by adding a polymer such as a thermoplastic elastomer as a modifier to straight asphalt. In the present invention, a polymer in which asphalt is dispersed and a polymer continuous phase is formed is used. A polymer continuous phase is formed when there is a large amount of polymer added and there is an asphaltene rich phase (asphalt is the main component) in the polymer rich phase (polymer is the main component), and the polymer is in the form of a continuous phase. It is what.

Examples of polymer-modified asphalt in which a polymer continuous phase is formed are described in the pavement design and construction guideline (2008 edition) published by the Japan Road Association, where there is generally a large amount of heavy vehicle traffic. The polymer modified asphalt type III used for the asphalt mixture applied to the above, and the polymer modified asphalt type H generally used for the porous asphalt mixture can be suitably used. More specifically, H type, H type-F, III type, III type-W
, Type III-WF can be used.

[mineral oil]
The mineral oil used in the present invention improves the softness of the polymer-modified asphalt at normal and low temperatures without destroying the polymer continuous phase of the polymer-modified asphalt, and improves the workability of the highly flexible asphalt mixture. It is added to make it better. As an example of the mineral oil, an industrial lubricating oil mainly composed of petroleum hydrocarbons having a pour point of −10 ° C. or lower can be suitably used. If the pour point of the mineral oil is higher than −10 ° C., the impact absorbability and the flexibility are lowered as described later.

  In addition, the mineral oil used in the present invention may be either a single petroleum hydrocarbon or an additive added. The mineral oil is not limited to industrial lubricating oil as long as it satisfies the pour point.

  The content of mineral oil is preferably 10 wt% to 30 wt% with respect to the polymer-modified asphalt. As will be described later, if it is less than 10 wt%, the softness of the polymer-modified asphalt cannot be improved, and the flexibility, vibration damping, crack resistance, and workability of the highly flexible asphalt mixture are lowered. On the other hand, if it exceeds 30 wt%, the polymer continuous phase of the polymer-modified asphalt is destroyed and the softening point is lowered, and the plastic deformation resistance of the highly flexible asphalt mixture is lowered, so that the flow resistance cannot be ensured.

[aggregate]
Aggregates used in the present invention are aggregates conventionally used in asphalt mixtures, such as crushed stone, sand, and stone powder, and are not limited to specific ones.

[Manufacture of highly flexible asphalt mixture]
When producing the highly flexible asphalt mixture of the present invention, polymer modification in which asphalt is dispersed in aggregate heated to 150 to 220 ° C. and polymer heated to 150 to 200 ° C. to form a polymer continuous phase Asphalt is mixed in a predetermined ratio, and a predetermined amount of mineral oil having a pour point of −10 ° C. or lower is added and mixed. Alternatively, a polymer modified asphalt in which asphalt is dispersed in a polymer heated to 150 to 200 ° C. in advance to form a polymer continuous phase and a mineral oil having a pour point of −10 ° C. or less are mixed in a predetermined ratio, and You may mix with the aggregate heated to 150-220 degreeC by the predetermined | prescribed ratio. These mixing procedures can be arbitrarily selected depending on the working environment, and may be performed in either order as long as the temperature during mixing is within the above range.

The polymer-modified asphalt is roughly classified into two types: a polymer continuous phase formed and an asphalt continuous phase formed. Among them, the present invention is characterized in that a polymer continuous phase is used.
Therefore, as an example of the polymer modified asphalt in which the polymer continuous phase of the present invention is formed, a polymer modified asphalt H type is used as Example 1, and the polymer continuous phase is not formed but the asphalt continuous phase is formed. As an example of the polymer modified asphalt, the one using the polymer modified asphalt II type is referred to as Comparative Example 1, and the one using the straight asphalt 60 to 80 used for ordinary asphalt pavement is used as Comparative Example 2 for the physics of the binder The test and various test results on the asphalt mixture using these binders will be described below.

[Example 1]
[Physical properties of the binder]
A binder physical test was conducted using Example 1 as a polymer-modified asphalt H type and a binder obtained by mixing 15 wt% of a mineral oil having a pour point of −30 ° C. with respect to the polymer-modified asphalt H type. Moreover, the physical test of the binder was done also about the comparative example 1 and the comparative example 2 which are shown below. The test results are shown in Table 1.

  In Comparative Example 1, the polymer modified asphalt H type is replaced with a binder obtained by mixing 15 wt% of a mineral oil having a pour point of −30 ° C. with respect to the polymer modified asphalt H type. This uses polymer-modified asphalt type II, which is used for anti-flow resistance measures. Since the polymer-modified asphalt type II has a small amount of polymer added to the asphalt, the polymer-rich phase exists in the asphaltene-rich phase, and the asphalt is in the form of a continuous phase.

  In Comparative Example 2, straight asphalt 60 used for ordinary asphalt pavement is used in place of a polymer-modified asphalt H type and a binder obtained by mixing 15 wt% of mineral oil having a pour point of −30 ° C. with respect to the polymer-modified asphalt H type. ~ 80 is used.

  From Table 1, it can be seen that Example 1 has an extremely high penetration compared to Comparative Example 1 and Comparative Example 2, and has a higher softening point than Comparative Example 1 and Comparative Example 2. Therefore, it is considered that the asphalt mixture using Example 1 in which the polymer continuous phase is formed as a binder has excellent flexibility and crack resistance compared to Comparative Example 1 and Comparative Example 2, and has flow resistance. It is done.

[Example 2]
[Properties of highly flexible asphalt mixture]
After the binders of Example 1, Comparative Example 1 and Comparative Example 2 shown in Table 1 were mixed with the aggregate, a dense asphalt mixture having a maximum particle size of 13 mm generally used for the surface layer of asphalt pavement was manufactured. This was compacted, a specimen was prepared, and various tests were performed. The bending test was conducted in accordance with “Pavement Survey / Test Method Handbook B005”.

The test results are shown in Table 2. In general, a dense asphalt mixture having a maximum particle size of 13 mm is excellent in water resistance and resistance to cracking.
Here, in the preparation of the specimen according to Example 2, the binder amount is 5.5%, the blending ratio of the aggregate is as shown in Table 3, and the aggregate particle size is as shown in Table 4. .

  From the bending test results in Table 2, the dense asphalt mixture using the binder of Example 1 has a bending strain that is about 4 times larger than that when the binder of Comparative Example 1 or Comparative Example 2 is used. It turns out that it is excellent in the property and crack resistance.

  Further, from the results of the Marshall test shown in Table 2, the dense-graded asphalt mixture using the binder of Example 1 has almost the same stability and flow value as those of Comparative Example 2 used for ordinary asphalt pavement. From the results of the tracking test, the dense asphalt mixture using the binder of Example 1 has a dynamic stability that is an index of plastic deformation resistance, which is used as a measure against flow resistance in asphalt pavement where there is a large amount of heavy vehicle traffic. Although it is lower than that in the case of using Example 1, it is higher than in the case of using Comparative Example 2, so that it can be seen that it has sufficient plastic deformation resistance.

[Example 3]
[Shock absorbency of highly flexible asphalt mixture]
The binder of Example 1, Comparative Example 1, and Comparative Example 2 shown in Table 1 and the aggregate were mixed to produce a coarse asphalt mixture having a maximum particle size of 20 mm, which is generally used for a base layer of asphalt pavement. Later, this is compacted, a specimen is prepared, and a pavement road surface elasticity test (pavement survey and test method manual S026-1) and a HIC test (ASTM F-1292-99) are performed, and shock absorption is achieved. evaluated. The coarse particle size asphalt mixture having a maximum particle size of 20 mm is generally excellent in properties such as flow resistance.

The test results are shown in Table 5. The GB coefficient represents impact absorbability. The smaller the value, the higher the impact absorbency. The SB coefficient represents the resilience, and the smaller the value, the lower the resilience. Gmax represents the maximum deceleration of impact, and HIC is a measure of impact strength. The smaller the value, the higher the impact absorption.
Here, in the preparation of the specimen according to Example 3, the binder amount is 4.9%, the blending ratio of the aggregate is as shown in Table 6, and the aggregate particle size is as shown in Table 7. .

From Table 5, the coarse-grained asphalt mixture using the binder of Example 1 has a GB coefficient of 8 to 11% smaller than that of the binder of Comparative Example 1 or Comparative Example 2, and the SB coefficient is also 6 to 8 % Small, it can be seen that the impact absorption is high and the impact resilience is also low.
In addition, the coarse-grained asphalt mixture using the binder of Example 1 has a lower Gmax and HIC than the case of using the binder of Comparative Example 1 or Comparative Example 2, and thus it is understood that the impact absorption is high. .

[Example 4]
[Vibration damping of highly flexible asphalt mixture]
After producing the asphalt mixture by mixing the binder and aggregate of Example 1, Comparative Example 1 and Comparative Example 2 shown in Table 1, this was compacted to produce a specimen having a two-layer structure, Based on “JIS G 0602 Vibration Damping Characteristics Test Method for Damping Steel Sheet”, a loss factor, which is an index of vibration damping, was measured at 20 ° C. to evaluate the vibration damping. The loss factor measurement results are shown in FIG. Note that the greater the value of the loss coefficient, the higher the vibration damping property.

  Here, in the preparation of the specimen according to Example 4, the surface layer is a dense particle size asphalt mixture using the binder of Comparative Example 1 shown in Example 2, and the base layer is the binder of Example 1 shown in Example 3, A coarse particle size asphalt mixture was obtained using the binder of Comparative Example 1 and the binder of Comparative Example 2, respectively. The types of specimens are as shown in Table 8.

  From FIG. 1, in the case of A in which the coarse particle size asphalt mixture using the binder of Example 1 was applied to the base layer, the coarse particle size using the binder of Comparative Example 1 of B or Comparative Example 2 of C as the base layer Compared to the case where the asphalt mixture is applied, the vibration damping property is high since it is about 4 times larger.

  From the test results of Examples 2 to 4 above, the asphalt mixture using the binder of Example 1 in which the polymer continuous phase is formed is more than the one using the binder of Comparative Example 1 or Comparative Example 2, It was confirmed that the object of the present invention is to exhibit the high flexibility, vibration damping, crack resistance, and plastic deformation resistance in a well-balanced manner.

  Next, the optimum amount of mineral oil added to the polymer-modified asphalt and the results of tests conducted to confirm the desired pour point of the mineral oil will be described below.

[Example 5]
[Additional amount of mineral oil and properties of the mixture]
A dense asphalt mixture having a maximum particle size of 13 mm, which is generally used for the surface layer of asphalt pavement, is produced by changing the amount of mineral oil added in the same amount of binder and aggregate as in Example 2, and then compacting the mixture. A specimen was prepared, and an HIC test (ASTM F-1292-99) and a wheel tracking test were performed. The test results are shown in FIGS.

  From FIG. 2, it can be seen that HIC tends to decrease as the amount of mineral oil added increases, and tends to decrease particularly when the amount added is 10 wt% or more. The smaller the value of HIC, the higher the impact absorbability. Therefore, high impact absorbability can be obtained by setting the amount of mineral oil added to 10 wt% or more.

FIG. 3 shows that the dynamic stability tends to decrease as the amount of mineral oil added increases. When the addition amount of mineral oil is 30 wt% or less, the dynamic stability is 500 or more, and a dense particle size asphalt mixture using straight asphalt 60 to 80 which is a general asphalt mixture shown in Comparative Example 2 in Table 2 (13 ) And the necessary plastic deformation resistance can be ensured.
Therefore, the amount of mineral oil added is desirably 10 wt% to 30 wt%.

[Example 6]
[Pour point of mineral oil and properties of mixture]
A dense asphalt mixture having a maximum particle size of 13 mm generally used for the surface layer of asphalt pavement is produced by changing the pour point of mineral oil with the same binder amount and aggregate blending ratio as in Example 2, and then compacting this. A specimen was prepared, and an HIC test (ASTM F-1292-99) and a bending test were performed. The test results are shown in FIGS.

  From FIG. 4, it can be seen that HIC tends to increase when the pour point of mineral oil is higher than −10 ° C. The smaller the value of HIC, the higher the impact absorbability. Therefore, when the pour point of mineral oil is higher than −10 ° C., the impact absorbability decreases.

FIG. 5 shows that the breaking strain tends to decrease as the pour point of the mineral oil increases, and in particular, tends to decrease when the pour point becomes higher than −10 ° C. The larger the value of the breaking strain, the better the flexibility. Therefore, when the pour point of the mineral oil is higher than −10 ° C., the flexibility is lowered.
Therefore, it is desirable that the pour point of the mineral oil is −10 ° C. or lower.

  From the results of Examples 5 and 6, the amount of mineral oil added to the polymer-modified asphalt is preferably 10 wt% to 30 wt%, and the pour point of the mineral oil is -10 ° C or lower. It was confirmed that this was desirable.

  The highly flexible asphalt mixture of the present invention can be used for the surface layer and base layer of asphalt pavement.

Claims (3)

  An aggregate, a polymer-modified asphalt in which a polymer continuous phase is formed by dispersing asphalt in a polymer, and a mineral oil having a pour point of −10 ° C. or less, wherein the mineral oil is less than the polymer-modified asphalt. A highly flexible asphalt mixture characterized by containing 10 wt% to 30 wt%.   A polymer in which a polymer continuous phase is formed by dispersing asphalt in an aggregate heated to 150 to 220 ° C and a polymer heated to 150 to 200 ° C in producing the highly flexible asphalt mixture according to claim 1. A method for producing a highly flexible asphalt mixture, comprising mixing with modified asphalt, and adding and mixing with mineral oil having a pour point of -10 ° C or lower.   When producing the highly flexible asphalt mixture according to claim 1, a polymer modified asphalt in which a polymer continuous phase is formed by dispersing asphalt in a polymer heated to 150 to 200 ° C in advance, and a pour point is -10. A method for producing a highly flexible asphalt mixture, comprising mixing a mineral oil having a temperature of not higher than 0C and an aggregate heated to 150 to 220C.

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