JP4323390B2 - Asphalt composition - Google Patents

Description

  The present invention relates to asphalt compositions. More particularly, the present invention relates to an asphalt composition for road paving.

Conventional asphalt pavement composites are manufactured by mixing heated aggregate and heat-melted asphalt, and the mixing temperature is 150 to 165 ° C in the case of straight asphalt 60-80. The manufactured asphalt pavement mixture is roller-rolled at 140 to 150 ° C. and used for asphalt pavement construction. If this temperature is too low, the aggregate and asphalt are poorly mixed, and the workability of the manufactured asphalt pavement composite material is deteriorated, and asphalt pavement having a predetermined performance cannot be obtained. In other words, it was impossible to construct asphalt pavement during mixing and lowering the temperature during construction. Therefore, as an attempt to lower the temperature and to mix and construct, (1) a method of foaming asphalt by blowing water or steam into asphalt in a heated and melted state (for example, see Non-Patent Document 1), (2) A method of forming bubbles in the melted asphalt by adding a foaming agent (see, for example, Non-Patent Document 2), (3) A method of adding diluent and cutting back and softening the asphalt (for example, non-patent) Reference 3) has been proposed.

In addition, asphalt conventionally used for asphalt pavement is obtained as a vacuum residue obtained in the crude oil refining process. In order to obtain asphalt with properties suitable for asphalt pavement, it is manufactured by selecting the type of crude oil used as a raw material. It is common. Examples of crude oils that can produce high-quality asphalt include naphthenic crude oils produced in South America, etc., and mixed crude oils produced in the Middle East, etc. Among these crude oils, crude oils that are relatively rich in heavy components are selected. Asphalt is manufactured. Specifically, Middle Eastern crude oil, which accounts for most of Japan's imported crude oil, is produced by processing specific heavy crude oil such as Kuwait crude oil, Iranian heavy crude oil, Kafuji crude oil, and Arabian heavy crude oil. In other words, asphalt for pavement is currently manufactured under conditions subject to the great restriction of selection of crude oil (see, for example, Non-Patent Document 4). On the other hand, when a relatively light crude oil is processed, only a vacuum residue that is not suitable for pavement can be obtained, and such a vacuum residue is finally used only as a fuel for combustion. .
Mima, Tokuman, Okamoto, “Example of construction of intermediate temperature mixture using foam door bitumen”, 23rd Japan Road Conference General Proceedings, 1999, p.156 Ebisawa, Sakamoto, Sasaki, Gotogi, “Medium warming technology using chemical foam asphalt”, pavement, vol. 10, 2000, p. 19 Suzuki, Nomura, Yamamoto, “Examination of viscosity reduction of asphalt”, 20th Annual Meeting of Japan Road Conference, 1993, p.448. Hasegawa, “Lecture on how to make paving materials asphalt”, 1999, Paving, vol. 6, 1999, p. 31

  The method of (1) described above for lowering the temperature at the time of mixing and construction has a problem that the influence of residual moisture, for example, the decrease in the adhesiveness between aggregate and asphalt is concerned. The method (2) has a problem that the effect is lost when bubbles formed by foaming disappear with time. In the method (3) described above, since the asphalt is cut back with a diluent, the physical properties of the asphalt are changed, and there is a problem that the performance of the asphalt pavement after construction, in particular, the rutting resistance is lowered.

  On the other hand, the reduced-pressure residual oil obtained when processing light crude oil may not be able to reduce the penetration to a level suitable for paving asphalt at refineries, even if it can be reduced to the desired penetration. However, there was a problem that the softening point of the vacuum residue and the viscosity at 60 ° C. were too low to ensure the performance of the asphalt pavement after construction, in particular, the resistance to rutting.

  Therefore, the present inventor obtained the same or better performance than the conventional one even when the mixing temperature and construction temperature of the asphalt pavement mixture are lowered, and obtained by processing crude oil rich in heavy components that has been used conventionally. The purpose of this study is to provide an asphalt composition that can perform as much as or better than conventional asphalt obtained by processing light crude oil that has not been used in the past. It was.

  As a result of intensive research on the above problems, the present inventor has the ability to improve the mixing property with aggregates in asphalt containing a polyolefin wax having specific physicochemical properties, and as a conventional paving asphalt Has found that it can be used as a paving material even when unsuitable vacuum residue is used, and has completed the present invention.

That is, the present invention has a molecular weight of 800 to 6500 with respect to a vacuum residual oil having a penetration at 25 ° C. of 60 to 160 (1/10 mm), a softening point of 38 ° C. or higher, and a 60 ° C. viscosity of 50 Pa · s or higher. Obtained by blending a polyolefin wax having a branching degree of 0.5 mol% or less, a crystallinity of 80 to 95, and a softening point of 110 to 140 ° C., and a penetration at 25 ° C. of 35 to 90 (1/10 mm), The present invention relates to an asphalt composition having a softening point of 90 to 130 ° C and an elongation at 15 ° C of 70 cm or more.
The present invention also relates to the asphalt composition as described above, wherein 2 to 8 parts by weight of the polyolefin wax is blended with 100 parts by weight of the vacuum residue.

  With the asphalt composition of the present invention, the mixing temperature during the production of the asphalt mixture can be kept low. As a result, it is possible to reduce the energy consumption and carbon dioxide emission required when producing the asphalt mixture, and reduce the smoke and odor generated during the production of the asphalt mixture. Furthermore, it is possible to use a reduced pressure residual oil which is not suitable as a conventional asphalt for pavement, that is, has a high penetration and a low viscosity at 60 ° C. as a pavement material.

  Hereinafter, the present invention will be described in detail.

(Penetration of vacuum residual oil)
The penetration at 25 ° C. of the vacuum residue used in the asphalt composition of the present invention needs to be 60 to 160 (1/10 mm). The lower limit of the penetration at 25 ° C. needs to be 60 (1/10 mm) or more from the viewpoint of improving the crack resistance of the asphalt pavement after construction because the asphalt composition after blending the polyolefin wax becomes too hard. 80 (1/10 mm) or more is preferable. On the other hand, the upper limit is 160 (1/10 mm) or less from the viewpoint of improving the resistance to rutting of the asphalt pavement after construction, which makes it difficult to maintain the hardness of the asphalt composition after blending the polyolefin wax. And 120 (1/10 mm) or less is preferable.
Here, the penetration at 25 ° C. is a value measured by JIS K2207 “Petroleum Asphalt—Penetration Test Method”.

(Softening point of vacuum residual oil)
The softening point of the vacuum residue used in the asphalt composition of the present invention needs to be 38 ° C. or higher. When the temperature is lower than 38 ° C., it is difficult to sufficiently increase the softening point of the asphalt composition even if a polyolefin wax is blended. Moreover, in order to improve the rutting resistance of the asphalt pavement after construction, 40 ° C. or higher is preferable. If the softening point exceeds 60 ° C., it becomes too viscous, and it becomes difficult to keep the mixing temperature and construction temperature low when manufacturing the asphalt pavement composite. Therefore, the upper limit of the softening point is preferably 60 ° C. or less.
The softening point as used herein is a value measured by JIS K2207 “Petroleum Asphalt—Softening Point Test Method”.

(60 ° C viscosity of vacuum residue)
The 60 ° C. viscosity of the vacuum residue used in the asphalt composition of the present invention needs to be 50 Pa · s or more, and further improves the resistance to rutting of asphalt pavement after construction by blending polyolefin wax. Therefore, 60 Pa · s or more is preferable. Further, the upper limit of the viscosity at 60 ° C. is preferably 450 Pa · s or less. If the upper limit exceeds 450 Pa · s, it becomes too viscous, and it becomes difficult to keep the mixing temperature and construction temperature low during the production of the asphalt pavement composite.
The 60 ° C. viscosity here is a value measured by “3-5-11 60 ° C. Viscosity Test Method” described in the Japan Road Association “Pavement Test Method Handbook”.

(Other properties of vacuum residue)
The elongation at 15 ° C. of the vacuum residue used in the asphalt composition of the present invention is not particularly limited, but is preferably 100 cm or more from the viewpoint of improving the crack resistance of the asphalt pavement after construction. Similarly, the flash point is preferably 260 ° C. or higher from the viewpoint of safety when used in an asphalt mixture plant.
Here, the elongation and flash point at 15 ° C. are as defined in JIS K2207 “Petroleum Asphalt—Elongation Test Method” and JIS K2265 “Crude Oil and Petroleum Products—Flash Point Test Method—Cleveland Open Type Flash Point Test Method”. The value to be measured.

(Type of vacuum residue)
The vacuum residue used in the asphalt composition of the present invention is preferably obtained by further vacuum distillation of the atmospheric distillation residue obtained after atmospheric distillation of the crude oil. Crude oil types include paraffinic crude oils such as Minas crude oil and Daqing crude oil, naphthenic crude oils such as Venezuela crude oil, intermediate base crude oils such as Arabian heavy crude oil, Kafuji crude oil, Kuwait crude oil, and so on. Preferred examples include crude oils such as Iranian light crude oil and Arabian extralite crude oil which are not suitable.

(Molecular weight of polyolefin wax)
The molecular weight of the polyolefin wax used in the asphalt composition of the present invention needs to be 800-6500. When the molecular weight is less than 800, the softening point of the asphalt composition does not sufficiently increase even when a polyolefin wax is blended, and there is a concern about the rutting resistance of the asphalt pavement composite. For this reason, the lower limit of the molecular weight of the polyolefin wax is preferably 1000 or more, and more preferably 2000 or more. On the other hand, if the molecular weight exceeds 6500, melt dispersibility in asphalt is lowered, and it is difficult to produce the asphalt composition of the present invention. For this reason, the upper limit of the molecular weight of the polyolefin wax is preferably 5000 or less, and more preferably 4500 or less.
The molecular weight of the polyolefin wax here refers to a weight average molecular weight (Mw) measured by GPC analysis (gel permeation chromatography analysis). For GPC analysis, Wander 150C-1 is used as an analyzer, PLgel MIXED-B is used as a separation column, o-dichlorobenzene is used as a solvent, a flow rate is 0.5 ml / min, and a differential refractometer ( RI) is used to measure the molecular weight by preparing a calibration curve with a polyolefin wax sample concentration: 1% by mass, implantation amount: 50 μl, and linear polyethylene.

(Branching degree of polyolefin wax)
The degree of branching of the polyolefin wax used in the asphalt composition of the present invention needs to be 0.5 mol% or less. When it exceeds 0.5 mol%, the softening point of the asphalt composition after blending the polyolefin wax cannot be increased, and there is a concern about the rutting resistance of the asphalt pavement composite material, which is not preferable. For this reason, the degree of branching is preferably 0.1 mol% or less.
In addition, the branching degree of polyolefin wax here is computed from the spectrum intensity ratio measured by < ¹³ > C-NMR analysis. The measurement conditions were Inova 400 as the measurement device, ¹³ C as the measurement nuclide (resonance frequency 100 MHz), complete decoupling method as the measurement method, 120 ° C. as the measurement temperature, and o-dichlorobenzene / heavy benzene = 3/1 as the solvent. The time is 10 seconds, the number of integration is 5000, and the degree of branching is determined by converting the amount of methyl branching calculated from the peak intensity ratio of the spectrum into mol% of propylene contained in the polyolefin wax molecule.

(Crystallinity of polyolefin wax)
The crystallinity of the polyolefin wax used in the asphalt composition of the present invention needs to be 80 to 95%. When the crystallinity is less than 80%, the softening point of the asphalt composition cannot be sufficiently increased even when the polyolefin wax is blended, and there is a concern about the resistance to rutting of the asphalt pavement mixture. For this reason, the lower limit of the crystallinity of the polyolefin wax is preferably 85% or more. On the other hand, if the crystallinity exceeds 95%, the elongation of the asphalt composition after blending the polyolefin wax is lowered, and there is a concern about the crack resistance of the asphalt pavement composite. For this reason, the upper limit of the crystallinity of the polyolefin wax is more preferably 90% or less.
In addition, the crystallinity degree of polyolefin wax here is measured by XRD analysis (X-ray diffraction analysis). As measurement conditions, X-ray source: CuKα, X-ray output: 30 kV-100 mA, 2θ = 5 to 145 deg, scanning speed: 1.2 deg / min, slit: variable mode, analysis is performed using a monochromator.

(Softening point of polyolefin wax)
The softening point of the polyolefin wax used in the asphalt composition of the present invention needs to be 110 to 140 ° C. If the softening point is less than 110 ° C., even if polyolefin wax is added, the softening point of the asphalt composition does not sufficiently increase, and there is a concern about the resistance to rutting of the asphalt pavement mixture, which is not preferable. On the other hand, if the softening point exceeds 140 ° C., it takes time to melt into asphalt, which is not preferable in terms of production efficiency.
The softening point as used herein is a value measured by JIS K2207 “Petroleum Asphalt—Softening Point Test Method”.

(Types of polyolefin wax)
The polyolefin wax used in the asphalt composition of the present invention is not particularly limited except that it has the predetermined properties described above, but is a high-density type polyethylene obtained by directly polymerizing ethylene by catalytic polymerization technology. Wax is particularly preferably used.

(Penetration of asphalt composition)
The penetration at 25 ° C. of the asphalt composition of the present invention needs to be 35 to 90 (1/10 mm). The lower limit of the penetration at 25 ° C is 35 (1 / 10mm) or more from the point of being able to improve the cracking resistance of asphalt pavement after construction, which can keep the mixing temperature and construction temperature during asphalt pavement compound production low. Is required, and 45 (1/10 mm) or more is preferable. On the other hand, the upper limit is 90 (1/10 mm) or less in order to prevent deterioration of the rutting resistance of the asphalt pavement after construction due to excessive penetration of the asphalt composition. / 10 mm) or less.
Here, the penetration at 25 ° C. is a value measured by JIS K2207 “Petroleum Asphalt—Penetration Test Method”.

(Softening point of asphalt composition)
The lower limit of the softening point of the asphalt composition of the present invention is required to be 90 ° C. or higher, and preferably 100 ° C. or higher from the viewpoint of preventing deterioration of the rutting resistance of the asphalt pavement after construction. On the other hand, the upper limit of the softening point is 140 ° C. or less, preferably 130 ° C. or less, from the viewpoint that the mixing temperature of the asphalt composition and aggregate and the compaction temperature during asphalt pavement construction can be lowered.
The softening point as used herein is a value measured by JIS K2207 “Petroleum Asphalt—Softening Point Test Method”.

(Elongation of asphalt composition)
The elongation at 15 ° C. of the asphalt composition of the present invention is required to be 70 cm or more, and preferably 100 cm or more from the viewpoint of improving the crack resistance of the asphalt pavement after construction.
Here, the elongation at 15 ° C. is a value measured by JIS K2207 “Petroleum Asphalt—Elongation Test Method”.

(Flash point of asphalt composition)
The flash point of the asphalt composition of the present invention is not particularly limited, but is preferably 260 ° C. or higher from the viewpoint of the safety of the workplace in the asphalt mixture plant.
Here, the flash point is a value measured according to JIS K2265 “Crude oil and petroleum products—flash point test method—Cleveland open flash point test method”.

(Combination ratio of vacuum residue and polyolefin wax)
The asphalt composition of the present invention preferably contains 2 to 8 parts by weight, more preferably 3 to 6 parts by weight, of the polyolefin wax with respect to 100 parts by weight of the vacuum residue.
When the blending ratio of the polyolefin wax with respect to 100 parts by weight of the vacuum residue is less than 2 parts by weight, the mixing property of the asphalt composition and the aggregate cannot be improved, and the mixing temperature and the construction temperature cannot be lowered. On the other hand, if the amount exceeds 8 parts by weight, the penetration of the asphalt composition is too small and too hard, which is not preferable because the crack resistance of the asphalt pavement composite material is concerned.

(Polyolefin wax blending method)
It is sufficient that the production temperature required for producing the asphalt composition of the present invention is equal to or higher than the melting point of the polyolefin wax, and preferably 140 to 200 ° C. The asphalt composition of the present invention can be produced simply by adding a polyolefin wax to a vacuum residue that has been heated to 140 to 200 ° C. using a heat melting tank and stirring and mixing. It is sufficient to stir with a general propeller shaft at about 10 to 600 rpm, and the stirring time is about 10 to 120 minutes. Further, although it can be produced using a high shear mixer or the like, stirring in a heating and melting tank is sufficient. Moreover, it is also possible to manufacture continuously by adding polyolefin wax with respect to the vacuum residue which heated at 140-200 degreeC using the line mixer.

(Composition of other base materials)
The asphalt composition of the present invention can also be used as a base asphalt of a modified asphalt that is generally produced conventionally. That is, for example, styrene-butadiene-styrene ternary block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene, which are thermoplastic elastomers, for the asphalt composition of the present invention. -Butylene-styrene block copolymer (SEBS) etc. can be added and used together. In addition, rubbers such as chloroprene rubber and natural rubber, and olefin copolymers such as ethylene / ethyl acrylate copolymer (EEA) and ethylene / vinyl acetate copolymer (EVA) can be mixed and used. Furthermore, aliphatic petroleum resins such as C5 petroleum resins, aromatic petroleum resins such as C9 petroleum resins, alicyclic petroleum resins such as dicyclopentadiene petroleum resins, C5 / C9 copolymer petroleum resins, etc. These petroleum resins and hydrogenated petroleum resins obtained by hydrogenating these petroleum resins may be blended. A synthetic wax such as Fischer-Tropsch wax may be added. In addition, lubricating oil fractions obtained from paraffinic, naphthenic and mixed base crude oils, and refinements obtained by subjecting these lubricating oil fractions to various refining processes such as solvent extraction, hydrorefining and dewaxing. Oil or the like may be added. In addition, you may mix | blend various peeling inhibitors which improve the adhesiveness of an aggregate and asphalt, various antioxidants etc. which improve the stability with respect to deterioration of an asphalt composition.
Production of a composite material for asphalt pavement by the composition of the present invention, and thereby road pavement can be performed by a conventional method.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[Examples and Comparative Examples]
Table 1 shows the properties of the vacuum residues A to D used in Examples 1 to 3 and Comparative Examples 1 to 6, and Table 2 shows the properties of the polyolefin waxes A to D. Table 3 shows the blending ratio of the vacuum residue and the polyolefin wax and the properties of the obtained asphalt composition.
The vacuum residue shown in Table 1 and the polyolefin wax shown in Table 2 were produced or obtained as follows.

(Reduced pressure residue A)
Iranian light crude oil, which is a typical light crude oil, was subjected to vacuum distillation under a temperature of 540 ° C. and a pressure of 45 mmHg to obtain a vacuum residue A having a penetration of 90. Table 1 shows the properties of the vacuum residue A.
(Reduced pressure residue B)
Straight asphalt 60-80 manufactured by NIPPON NIPPON OIL CO., LTD. And straight asphalt 150-200 were mixed together to obtain a vacuum residue B having a penetration of 140. Table 1 shows the properties of the vacuum residue B.
(Reduced pressure residue C)
Straight asphalt 40-60 manufactured by Nippon Oil Corporation Negishi Refinery was used as the vacuum residue C. Table 1 shows the properties of the vacuum residue C.
(Vacuum residue D)
Straight asphalt 150-200 manufactured by Shin Nippon Oil Co., Ltd. Negishi Refinery was used as the vacuum residue D. Table 1 shows the properties of the vacuum residue D.

The physical property value measuring method of the vacuum residue in Table 1 is as follows.
Density (@ 15 ° C): JIS K2207 "Petroleum Asphalt-Density Test Method"
Penetration (@ 25 ° C): JIS K2207 "Petroleum Asphalt-Penetration Test Method"
Softening point: JIS K2207 "Petroleum asphalt-Softening point test method"
Viscosity at 60 ° C .: “3-5-11.
60 ° C Viscosity Test Method "
Elongation (@ 15 ° C): JIS K2207 "Petroleum Asphalt-Elongation Test Method"
Flash point: JIS K2265 "Crude oil and petroleum products-Flash point test method-Cleveland open-type flash point test method"

(Polyolefin wax A)
High wax 100P manufactured by Mitsui Chemicals, Inc.
(Polyolefin wax B)
High wax 400P manufactured by Mitsui Chemicals, Inc.
(Polyolefin wax C)
High wax 420P manufactured by Mitsui Chemicals, Inc.
(Polyolefin wax D)
High wax 800P manufactured by Mitsui Chemicals, Inc.

The physical property test methods for the polyolefin wax in Table 2 are as follows.
Density (@ 23 ° C.): JIS K7112 “Plastics—Method of measuring density and specific gravity of non-foamable plastics B method (pycnometer method)”
Molecular weight: weight by the GPC average molecular weight _{M W}
Branching degree: Calculated from the spectral intensity ratio by ¹³ C-NMR analysis Crystallinity: Measured by XRD (X-ray diffraction analysis) Softening point: JIS K2207 “Petroleum asphalt-softening point test method”

Table 3 shows the blending ratio of the vacuum residue and the polyolefin wax and the properties of the obtained asphalt composition. The properties of the asphalt composition were measured by the following method.
The density (@ 15 ° C.) refers to a value of density at 15 ° C. measured by JIS K2207 “Petroleum Asphalt—Density Test Method”.
The penetration (@ 25 ° C.) refers to the value of penetration at 25 ° C. measured by JIS K2207 “Petroleum Asphalt—Penetration Test Method”.
The softening point refers to a value measured according to JIS K2207 “Petroleum Asphalt—Softening Point Test Method”.
The elongation (@ 15 ° C.) refers to the elongation at 15 ° C. measured by JIS K2207 “Petroleum Asphalt—Elongation Test Method”.
The flash point is a value measured according to JIS K2265 “Crude oil and petroleum products—flash point test method—Cleveland open type flash point test method”.

Next, the tests shown below were performed on the asphalt compositions of Examples 1 to 3 and Comparative Examples 1 to 6 shown in Table 3. The results are shown in Table 5. As the asphalt mixture used in the test, a dense-graded asphalt mixture (13) obtained by heating and mixing aggregate and asphalt at the blending ratio shown in Table 4 was used.
Wheel Tracking Test: 3-7-3 “Wheel Tracking Test Method” in the Japan Road Association “Pavement Test Method Handbook”
An asphalt mixture obtained by heating and mixing asphalt and aggregate is put in a predetermined mold (300 × 300 × 50 mm), and a test piece is reciprocated in a constant temperature room at 60 ° C. with a small wheel with a specified load (686 ± 10 N). The amount of deformation (rubbing amount) at 60 minutes and 60 minutes is measured, the dynamic stability (times / mm) is determined, and the resistance of the mixture to rutting is evaluated.
The larger the value of the dynamic stability (DS), the better the rutting resistance of the asphalt mixture at high temperature. Generally, in order to prevent rutting, the dynamic stability needs to be 500 times / mm or more. Judgment was carried out with ◯ for 500 times / mm or more and x for less than 500 times / mm. The specimen was prepared under the mixing temperature of 155 ° C. and the compaction temperature of 145 ° C.

Bending test: 3-7-5 “Bending test method” of the Japan Road Association “Pavement Test Method Handbook”
An asphalt mixture obtained by heating and mixing asphalt and aggregate is put into a predetermined formwork (300 x 300 x 50 mm) and shaped, and then a test piece having a shape of 300 x 100 x 50 mm is cut out to prepare a test temperature. After curing, the specimen is set on a loading tester and concentratedly loaded in the center at a loading speed of 50 mm / min. The maximum load is shown until the specimen breaks, and the bending strength at the time of breaking (at the maximum load) is obtained. Perform a bending test at the test temperatures of -5 ° C, 0 ° C, + 5 ° C, + 10 ° C, +15, and + 20 ° C, read the temperature at which the bending strength reaches the maximum value, and use this temperature as the embrittlement point Defined. The lower the embrittlement point of the specimen, the better the asphalt pavement with better crack resistance. When the embrittlement point of the specimen was less than + 15 ° C., it was judged as ○, and when it was + 15 ° C. or more, it was judged as x. The specimen was prepared under the mixing temperature of 155 ° C. and the compaction temperature of 145 ° C.

Mixing and compaction test:
Evaluation of mixability and compaction of the mixture was conducted by the Japan Road Association “Pavement Test Method Handbook” 3-7-1. Judgment was made based on the Marshall stability evaluated according to the Marshall stability test method and the porosity of the specimen. That is, heated aggregate, filler, and asphalt were mixed at 155 ° C., and then compacted at 145 ° C. to prepare a Marshall specimen. After the specimen returned to room temperature, the porosity of the specimen was confirmed. The Marshall stability was then evaluated. This temperature condition is a standard temperature condition.
Next, in order to evaluate the mixing property and compaction property, a specimen was prepared at a temperature condition lower by 30 ° C. than the standard temperature, that is, the mixing temperature with the aggregate was 125 ° C., and the compaction temperature was 115 ° C. Similarly, the porosity and Marshall stability of the specimens were evaluated. This temperature condition is set as a temperature suppression condition.
Even in the temperature suppression condition, when the Marshall stability was 10 kN or more and the porosity was 6% or less, it was judged as “poor” when any one of ○, Marshall stability and porosity was not satisfied.

The results are summarized in Table 5, and the results shown in Table 5 indicate the following.
In all of Examples 1 to 3, the dynamic stability evaluated by the wheel tracking test is 500 times / mm or more, and has good rutting resistance.
In all of Examples 1 to 3, in the mixing and compaction test, the Marshall stability was 12 kN or higher and the porosity of the specimen under the temperature suppression condition of 30 ° C. lower than the standard compaction temperature of 145 ° C. Is less than 5%, and it can be seen that it has good mixing properties and compaction properties. That is, it shows that the low mixing temperature and construction temperature in the pavement work by the asphalt pavement compound are possible.
Further, in all of Examples 1 to 3, the embrittlement point of the asphalt mixture evaluated by a bending test is + 15 ° C. or less, and shows good crack resistance.
On the other hand, in Comparative Example 1, since the polyolefin wax used has a high degree of branching and a low crystallinity, the softening point of the asphalt composition obtained after the addition of the polyolefin wax cannot be sufficiently increased. As a result, the dynamic stability evaluated by the wheel tracking test was low, and the rutting resistance was inferior.

Further, in Comparative Example 2, since the penetration of the vacuum residual oil is too large, the penetration is not sufficiently reduced even when a predetermined polyolefin wax is added, and the softening point cannot be sufficiently increased. That is, the asphalt composition after the addition of the polyolefin wax could not secure a sufficient hardness, so that the dynamic stability evaluated by the wheel tracking test was as low as 320 times / mm, resulting in poor rutting resistance.
Comparative Example 3 shows no problem in the dynamic stability evaluated by the wheel tracking test, but because of the excessive amount of polyolefin wax added, the embrittlement point evaluated by the bending test is higher than + 15 ° C. The result was inferior in cracking properties.
Although Comparative Example 4 also shows no problem in the dynamic stability evaluated by the wheel tracking test, the embrittlement point evaluated by the bending test is more than + 15 ° C. because the penetration of the vacuum residue used is too small. The result was high and inferior in crack resistance.

  In Comparative Examples 5 and 6, there is no problem in the dynamic stability evaluated by the wheel tracking test and the embrittlement point evaluated by the bending test. However, in Comparative Example 5, the molecular weight of the polyolefin wax to be added is too large, and the mixing property with the aggregate and the compaction property of the specimen are deteriorated. As a result, the Marshall stability of the specimen obtained under the temperature suppression condition is low. Since the porosity of the specimen increased, it was impossible to reduce the mixing temperature and the compaction temperature of the aggregate and the vacuum residual oil. Moreover, since the polyolefin wax is not added in Comparative Example 6, the mixing property with the aggregate and the compaction property of the specimen are also deteriorated. As a result, the Marshall stability of the specimen obtained under the temperature suppression condition is low. However, it was impossible to lower the mixing temperature and the compaction temperature of the aggregate and the vacuum residual oil as the porosity of the specimen increased.

Claims (2)

  The molecular weight is 800 to 6500 and the degree of branching is 0.5 mol with respect to reduced pressure residual oil having a penetration of 60 to 160 (1/10 mm) at 25 ° C., a softening point of 38 ° C. or more and a viscosity of 60 ° C. of 50 Pa · s or more. %, A crystallinity of 80 to 95%, a penetration degree at 25 ° C. of 35 to 90 (1/10 mm), and a softening point of 90 to 90% obtained by blending a polyolefin wax having a softening point of 110 to 140 ° C. An asphalt composition characterized by having an elongation at 130 ° C and 15 ° C of 70 cm or more.   2. The asphalt composition according to claim 1, wherein 2 to 8 parts by weight of a polyolefin wax is blended with 100 parts by weight of the vacuum residue.