JP2006143954A - Modified asphalt, manufacturing method of modified asphalt and asphalt mixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a modified asphalt having excellent quality which is cheep and manufacturable at a temperature near the conventional asphalt manufacturing temperature, its manufacturing method and a uniform asphalt mixture. <P>SOLUTION: The modified asphalt comprises a waste plastic containing as the major component at least one of a waste polystyrene, a waste polypropylene and a waste polyethylene; asphalt; and an additive compatible with the asphalt and exhibiting high affinity to the waste plastic. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a modified asphalt used for road pavement, a method for producing the modified asphalt, and an asphalt mixture.

  Conventional asphalt pavement material uses asphalt obtained from residues obtained by collecting light fractions such as naphtha and gasoline from crude oil, and asphalt has an action of caking aggregates such as sand and crushed stone. In this way, asphalt road pavement is constructed by adding asphalt as a binder to crushed stone and sand. As a result, there are problems such as cracking, low wear resistance and short service life. For this reason, modified asphalt mixed with a modifying material has been developed and used a lot. As this modifier, for example, a styrene / butadiene copolymer or a thermoplastic elastomer is used in order to improve wear resistance and fluid resistance.

  On the other hand, modified asphalt has also been developed in which waste plastic is also used effectively and waste plastic is added to asphalt (see, for example, Patent Document 1). In this technology, polyethylene terephthalate (PET) resin is used as waste plastic, and PET resin, waste oil, and asphalt are heated and mixed at a predetermined ratio, so that the PET resin does not precipitate even in asphalt and has a Marshall stability of 500 kgf (approximately A modified asphalt having a quality of 5 kN) or higher is obtained.

In order to effectively use waste plastics, research is also under way to obtain a quality equivalent to or better than that of conventional wastewater asphalt mixtures by replacing part of high-viscosity asphalt in wastewater asphalt mixtures with waste plastics. . Drainable high-viscosity asphalt mixture has a porosity of about 20%, so rainwater can be drained rapidly from the road surface, which has the advantage of improving the driving safety of the car, but is expensive and improved in durability. There is room. Therefore, if a high-quality paving material can be obtained by mixing waste plastic, it is useful from the viewpoint of resource and energy saving.
JP 2003-12932 A

  The technology described in Patent Document 1 discloses a method of obtaining a modified asphalt by mixing PET, edible oil, and asphalt in a heated ratio at a predetermined ratio, and in this modified asphalt, PET is It is not dissolved in asphalt and the PET melt does not precipitate in the asphalt. However, considering the storage and use of the modified asphalt, it is desirable that the modified asphalt has a modifying material such as PET dissolved in the asphalt. In addition, since the technology described in Patent Document 1 uses PET as a modifying material, the temperature during the production of modified asphalt is increased, but the modified asphalt is produced at a temperature close to the existing asphalt production temperature. It is desirable to be able to do it.

  In addition, in the technology of replacing a part of the high viscosity asphalt of the drainage asphalt mixture with waste plastic, the melting temperature of the waste plastic does not decrease sufficiently by simply mixing and melting the waste plastic and asphalt, Moreover, it is difficult to obtain a uniform mixture of the pavement mixture containing the aggregate.

  An object of the present invention is to provide a modified asphalt that is inexpensive and excellent in quality that can be produced at a temperature close to the existing asphalt production temperature, a production method thereof, and a uniform asphalt mixture.

The present invention is a waste plastic mainly composed of at least one of waste polystyrene, waste polypropylene, waste polyethylene,
With asphalt,
An additive having compatibility with the asphalt and exhibiting high affinity for the waste plastic;
It is a modified asphalt characterized by including.

  In the present invention, the additive is a modified asphalt according to claim 1, wherein the additive is a waste oil mainly composed of a waste engine oil.

  In the present invention, the additive is contained in the modified asphalt in an amount of 3 to 9% by weight.

  In the present invention, the waste plastic is the modified asphalt according to any one of claims 1 to 3, wherein the modified asphalt is contained in an amount of 10 to 40% by weight.

The present invention also provides the modified asphalt according to any one of claims 1 to 4,
Aggregate, and
The additive is an asphalt mixture characterized by exhibiting high affinity with the aggregate.

  In the present invention, the additive is an asphalt mixture according to claim 5, which is a surface modifier that changes the surface of the aggregate from hydrophilic to oleophilic.

  Moreover, this invention is an asphalt mixture of Claim 5 or 6 whose ratio of this waste plastic in the said asphalt mixture is 4-18 weight%.

Further, the present invention is a method for producing a modified asphalt containing a waste plastic mainly composed of at least one of waste polystyrene, waste polypropylene, and waste polyethylene,
A predetermined amount of waste plastic and an additive that is compatible with asphalt and has high affinity for the waste plastic are stirred and mixed under heating.
A method for producing modified asphalt, which comprises stirring and mixing a mixture of waste plastic and additive melted by stirring and mixing under heating, and asphalt heated to substantially the same temperature as the mixture.

  Since the modified asphalt of the present invention is a waste plastic mainly composed of at least one of waste polystyrene, waste polypropylene, and waste polyethylene, the modified asphalt can be produced at low cost. Moreover, waste plastic can be used effectively. In addition, because it contains additives that are compatible with asphalt and have high affinity for waste plastics, it is possible to produce modified asphalt that has high affinity for asphalt and waste plastics and that is uniform and excellent in quality. . In addition, the modified asphalt uses waste plastics mainly composed of at least one of waste polystyrene, waste polypropylene, and waste polyethylene, so the melting temperature of the waste plastics is relatively low, and the conventional asphalt production equipment is used as it is. Can be manufactured at low cost.

  Further, according to the present invention, since the additive is waste oil mainly composed of waste engine oil, it has compatibility with asphalt and exhibits high affinity for waste plastic. Since it is waste engine oil, modified asphalt can be produced at low cost. Furthermore, the disposal cost of the waste engine oil becomes unnecessary, and the waste engine oil can be used effectively.

  Moreover, according to this invention, the mixing ratio of an additive is 3 to 9 weight% with respect to a modified asphalt, and it exhibits an effect in a small quantity. Moreover, the range of the mixing ratio of the additive to the modified asphalt is as wide as 3 to 9% by weight, so that the modified asphalt can be easily prepared and manufactured.

  Further, according to the present invention, since the waste plastic is contained in the modified asphalt in an amount of 10 to 40% by weight, the range of the ratio of the waste plastic that can be mixed with the modified asphalt is wide, and the production becomes easy. Further, since a relatively large amount of waste plastic can be mixed into the asphalt, the modified asphalt can be manufactured at a low cost. In addition, waste plastic can be used effectively.

  Further, the present asphalt mixture includes a modified asphalt containing waste plastic, asphalt, and an additive having compatibility with the asphalt and showing high affinity for the waste plastic, and an aggregate, and is added. Since the agent shows high affinity with the aggregate, it is possible to produce a uniform and excellent asphalt mixture.

  According to the present invention, since the additive is a surface modifier that changes the surface of the aggregate from hydrophilic to lipophilic, the affinity between the aggregate and the modified asphalt is increased, and the quality is uniform. An excellent asphalt mixture can be produced.

  Moreover, according to this invention, since the ratio of the waste plastic in an asphalt mixture is 4-18 weight%, many waste plastics can be mixed. An asphalt mixture with a large amount of waste plastic and excellent quality can be produced.

  According to the present invention, the waste plastic is a waste plastic mainly composed of at least one of waste polystyrene, waste polypropylene, and waste polyethylene, and is compatible with a predetermined amount of waste plastic and asphalt. And an additive exhibiting high affinity for waste plastic, and a mixture of the waste plastic and additive melted by stirring and mixing under heating, and asphalt heated to substantially the same temperature as the mixture; Thus, uniform modified asphalt can be easily produced.

  An example of the manufacturing procedure of the modified asphalt and asphalt mixture of this invention is shown. The manufacturing procedure is not limited to this. First, a plastic that has been heated and melted and an additive that has a high affinity with the plastic that has been heated to substantially the same temperature as the plastic are mixed and stirred at a predetermined ratio to be uniform. Plastics and additives have high affinity, so they can be easily homogenized. As the plastic, a thermoplastic resin mainly composed of polyethylene, polypropylene, polystyrene, or the like can be used. These can be used alone or in combination. In view of the quality of the modified asphalt, polystyrene is particularly suitable.

  Although it is possible to use unused plastics, it is preferable to use waste plastic because it leads to effective use of the waste plastic and can produce modified asphalt at low cost. Waste plastic may be industrial waste discharged from factories, etc., or general waste discharged from households. A small amount of foreign matter such as glass, earth, paper, etc. is mixed in the target waste plastic. Also good. Specifically, waste foamed polystyrene such as ground plane wood, toro boxes, and trays can be used.

  Engine oil and lubricating oil can be used as the additive. These can be used alone or in combination. Furthermore, these do not need to be unused, and may be used waste oil. Considering waste oil treatment and cost, waste engine oil is preferable. In addition, when plant oils such as orienic acid ester, maleic acid, and ester acid are used instead of engine oil and lubricating oil, desired modified asphalt cannot be obtained.

  Next, asphalt heated to substantially the same temperature as the mixture is put into a mixture of the plastic and additive in a molten state under heating, and these are stirred and mixed under heating to make uniform. Engine oil or lubricating oil or a mixture thereof used as an additive is compatible with asphalt, so that the mixture and asphalt are easily homogenized. As the asphalt, straight asphalt, blown asphalt, modified asphalt to which a thermoplastic elastomer or the like is added, and mixed asphalt can be used, but it is preferable to use straight asphalt from the viewpoint of price. The modified asphalt can be obtained by the above operation.

  The mixing ratio of the additive to the modified asphalt (additive, plastic mixed asphalt) is preferably 3 to 9% by weight. The mixing ratio of the more preferable additive to the modified asphalt is 3 to 5% by weight. As shown in the examples described later, when the mixing ratio of the additive is 3% by weight or less, the surface hardening rate of the modified asphalt becomes too fast. On the other hand, even if the mixing ratio of the additive to the modified asphalt is 9% by weight, the desired modified asphalt can be obtained. Thus, in the present invention, a desired effect can be obtained by mixing a small amount of additives. Moreover, since the mixing ratio of the additive to the modified asphalt has a certain width, the production of the modified asphalt is facilitated.

  The mixing ratio of plastic to modified asphalt (additive, plastic mixed asphalt) is preferably 10 to 40% by weight. More preferably, it is 20 to 30% by weight. When the mixing ratio of the plastic to the modified asphalt is less than 10% by weight, the desired strength may not be obtained when an aggregate is added to form an asphalt mixture. In addition, plastic consumption is low, and waste plastic cannot be used effectively. On the other hand, when the mixing ratio of the plastic to the modified asphalt is 40% by weight or more, the surface hardening rate of the modified asphalt becomes too fast. Since many plastics can be mixed as described above, it greatly contributes to the effective use of waste plastics. Moreover, since the range of the mixing ratio of plastic to the modified asphalt is as wide as 10 to 40% by weight, the production of the modified asphalt becomes easy.

  As a technique similar to the present invention, a technique is disclosed in which petroleum resin containing styrene or the like is mixed into modified asphalt (aromatic mineral oil + thermoplastic elastomer + asphalt) (Japanese Patent Laid-Open No. 6-107953). In this technique, the maximum amount of petroleum resin mixed is 20% by weight. The reason why the maximum amount of the petroleum resin mixed is 20% by weight is that even if the amount exceeds 20% by weight, the effect of suppressing the separation of the thermoplastic elastomer does not increase with respect to the increase, and the cost increases. Compared to this, the present invention is characterized in that the mixing ratio of plastic in the modified asphalt is as large as 40% by weight at maximum. By increasing the amount of plastic mixed in, high quality modified asphalt can be obtained. In the present invention, waste plastic can be used, which is advantageous in terms of cost.

  Further, as a technique similar to the present invention, a technique using PET resin as a modified asphalt modifier is disclosed (Japanese Patent Laid-Open No. 2003-12932), but the melting point of PET is as high as about 280 ° C. . For this reason, the PET mixed modified asphalt needs to be produced at a high temperature. On the other hand, the polystyrene foam that can be used in the present invention is made of polystyrene. The polystyrene has a glass transition point of about 100 ° C., the melting point of polyethylene is 146 ° C., and the melting point of polypropylene is 148 to 185 ° C. Modified aphalt can be produced at a temperature of about 0C. Thus, since the modified asphalt can be produced at a temperature in the vicinity of the existing asphalt production temperature, the existing asphalt production equipment can be used as it is, and the modified asphalt can be produced at a low cost.

  Furthermore, the present invention is also characterized in that even when the mixing ratio of the plastic in the modified asphalt is large, the required additive amount (mixing ratio) of the additive is small. As shown in the examples described later, when the mixing ratio of the waste plastic in the modified asphalt is 38.5% by weight, the required mixing ratio of the additive is 3.8% by weight. On the other hand, for example, according to the data disclosed in Japanese Patent Application Laid-Open No. 2003-12932, when the mixing ratio of PET in the modified asphalt is 37.5% by weight, the mixing ratio of the additive required is 12. 5% by weight. From this result, it can be seen that the present invention has a smaller proportion of the addition amount required to produce the modified asphalt than the known invention.

  In order to obtain an asphalt mixture, aggregates used in ordinary asphalt mixtures such as sand and crushed stone may be mixed into the modified asphalt and stirred. By stirring and mixing them, a uniform asphalt mixture can be obtained. The additive contained in this modified asphalt has an affinity with aggregates, and functions as a surface modifier for aggregates, and the affinity between modified asphalt (waste plastic mixed asphalt) and aggregates. Since it functions to improve the properties, a uniform asphalt mixture can be easily produced.

  On the other hand, conventional modified asphalt is lipophilic, and aggregates such as sand exhibit properties that are contrary to hydrophilicity. Therefore, simply mix and mix aggregates such as sand and crushed stone into modified asphalt. However, the aggregate is not uniformly mixed and dispersed. To solve this, the surface of the aggregate may be modified to make it oleophilic, and there is a method using a surface modifier such as a silane coupling agent. The quality agent is expensive, and the modified asphalt cannot be produced at a low cost.

  Engine oil has an affinity for the cylinder, and has a seal between the piston ring and the cylinder, and acts to prevent wear and seizure. The cylinder is metal and the surface is hydrophilic. For that purpose, engine oil completely wets its metal surface during operation and retains its affinity with hydrophilic metal surfaces even at the temperature at which the engine is operating, i.e. at high temperatures. This indicates that engine oil has a high affinity with hydrophilic substances. This is the basis for selecting engine oil as an aggregate modifier of the present invention.

  As described above, engine oil is compatible with asphalt, has high affinity with plastics and aggregates such as polystyrene, and the surface of the aggregate is modified from hydrophilic to oleophilic. It can be used in asphalt mixtures. The same applies to a lubricating oil and a mixture of engine oil and lubricating oil.

  The mixing ratio of the plastic to the asphalt mixture is preferably 4 to 18% by weight, more preferably 4 to 13% by weight. When the ratio of the plastic to the asphalt mixture is 4% by weight or less, there are cases where the desired strength cannot be obtained depending on the intended use. In addition, when waste plastic is used as plastic, the amount of plastic consumed is small and the waste plastic cannot be effectively used. Further, when the mixing ratio of the plastic with respect to the asphalt mixture is 18% by weight or more, a uniform quality asphalt mixture cannot be obtained.

  If the mixing ratio of the plastic to the asphalt mixture is replaced with the plastic asphalt replacement ratio, the replacement ratio is a maximum of 40% (the mixing ratio of the plastic to the asphalt mixture is 18% by weight). The optimum flow value of the asphalt mixture is generally said to be 20 to 40. When this point is taken into consideration, the maximum value of the substitution ratio is about 25%.

  In addition to the procedure shown above, the modified asphalt can be produced in a uniform asphalt mixture by simultaneously putting the plastic, additive and asphalt heated to a predetermined temperature into the stirring and mixing device and stirring and mixing them. It can also be obtained. However, it is easier to obtain uniform modified asphalt in the procedure in which the plastic and the additive are stirred and mixed in a heated state in advance and then mixed with asphalt after forming the mixture.

  In addition, as the asphalt mixture manufacturing procedure, procedures other than those shown above can be used. For example, plastic, additive, and sand each heated to a predetermined temperature are simultaneously put into a stirring and mixing device to obtain a mixture by stirring and mixing, and then the mixture, asphalt and aggregate are stirred and mixed in a heated state. It is also possible to obtain a uniform asphalt mixture.

Furthermore, plastics, additives, and asphalt, each heated to a predetermined temperature, are put into a stirring and mixing device, mixed with stirring to obtain a mixture, and then cooled to obtain a solidified product. Since this premixed solidified product does not have a high melting point, it is also possible to produce an asphalt mixture by heating and melting the solidified product again at the plant or paving site and mixing with the heated aggregate in the same manner.
Example 1 A modified asphalt was prototyped and evaluated in the following manner. The materials used are listed in Table 1.

表１に示す材料を用いて、次の手順で改質アスファルトの製造を行なった。加温して溶融した廃プラスチックに、廃プラスチックとほぼ同一の温度に加熱した表面改質剤を所定量添加した。これを攪拌混合して均一な混合物を得た。この混合物に混合物と略同一に加熱した所定量のアスファルトを投入し、攪拌混合し改質アスファルトを得た。各材料の配合割合（重量割合）を表２に示す。表２において、ＲｕｎＮｏ実―１〜実―１３は、本発明の実施例を、ＲｕｎＮｏ比―１〜比―４は、比較例を示す。表３に実施例及び比較例の目視観察結果を記載した。

Using the materials shown in Table 1, modified asphalt was produced by the following procedure. A predetermined amount of a surface modifier heated to substantially the same temperature as the waste plastic was added to the waste plastic that was heated and melted. This was stirred and mixed to obtain a uniform mixture. A predetermined amount of asphalt heated substantially the same as the mixture was put into this mixture, and stirred and mixed to obtain modified asphalt. Table 2 shows the blending ratio (weight ratio) of each material. In Table 2, RunNo Real-1 to Real-13 indicate examples of the present invention, and RunNo ratio-1 to Ratio-4 indicate comparative examples. Table 3 shows the results of visual observation of the examples and comparative examples.

表３の結果から発泡スチロール（ポリスチレン）を用いて良好な改質アスファルトを得るためには、改質アスファルト中の表面改質剤の混合割合を３．８重量％にすればよいことが分かった。また同時に改質アスファルト中のポリスチレンの割合は、１０〜４０重量％程度が適切であることが分かった。改質アスファルト中の表面改質剤の割合が３．８重量％であっても、改質アスファルト中のポリスチレンの割合が５０重量％程度になると（ＲｕｎＮｏ実―４）、アスファルト中に発泡スチロールを混入することはできるが、表面硬化が早過ぎた。同様に改質アスファルト中の表面添加剤の濃度を約５重量％と高くしても、改質アスファルト中のポリスチレンの割合が５０重量％程度になると（ＲｕｎＮｏ実―５）、アスファルト中に発泡スチロールを混入することは可能であるが、表面硬化が早過ぎた。

From the results of Table 3, it was found that in order to obtain a good modified asphalt using polystyrene foam (polystyrene), the mixing ratio of the surface modifier in the modified asphalt should be 3.8% by weight. At the same time, the ratio of polystyrene in the modified asphalt was found to be about 10 to 40% by weight. Even if the proportion of the surface modifier in the modified asphalt is 3.8% by weight, when the proportion of polystyrene in the modified asphalt is about 50% by weight (Run No. 4), the polystyrene is mixed into the asphalt. Can be done, but surface hardening was too early. Similarly, even if the concentration of the surface additive in the modified asphalt is increased to about 5% by weight, when the proportion of polystyrene in the modified asphalt is about 50% by weight (Run No. Real-5), the polystyrene is added to the asphalt. Although it was possible to mix, surface hardening was too early.

  The thermoplastic resin that can be mixed with the modified asphalt is not limited to polystyrene, and polyethylene terephthalate (PET), high-density polyethylene (HDPE), and polystyrene (PP) can also be used (Run No. Real-10). ~ Real -13). The mixing ratio of the additive to the modified asphalt at this time was 9.0 to 9.1% by weight.

  Example 2 An asphalt mixture was prototyped and evaluated in the following manner. The raw materials shown in Table 1 were used as the raw materials used. A predetermined amount of aggregate was mixed into the modified asphalt that showed good results in Example 1, and then stirred and mixed to make it uniform. The blending ratio (weight ratio) is shown in Table 4. In addition, the waste plastic used here is a polystyrene foam (tray).

ＲｕｎＮｏ実―２１〜実―２４及びＲｕｎＮｏ比―２１（比較例）で試作したアスファルト混合物の品質を測定した。品質測定には、マーシャル試験（５０回締め固め）でマーシャル安定度とフロー値を測定した。マーシャル安定度は、アスファルト混合物の強度を示す物性値の一つで、測定は常法（例えば、社団法人日本道路協会；舗装試験法便覧 別冊，ｐ５０６〜ｐ５１６，１９９６）に従って行なった。フロー値は、アスファルト混合物のマーシャル安定度試験において、最大荷重を示したときの供試体の変形量（１／１００ｃｍ）である。これについてもマーシャル安定度と同様、常法に従って行なった。

The quality of the asphalt mixture prepared with Run No. Real-21 to Real-24 and RunNo ratio-21 (comparative example) was measured. For quality measurement, the Marshall stability and flow value were measured by a Marshall test (50 compaction). Marshall stability is one of the physical property values indicating the strength of the asphalt mixture, and the measurement was performed according to a conventional method (for example, Japan Road Association; pavement test method manual, p506 to p516, 1996). The flow value is a deformation amount (1/100 cm) of the specimen when the maximum load is shown in the marshall stability test of the asphalt mixture. This was performed according to a conventional method as in the Marshall stability.

  The measurement results are shown in FIGS. Marshall stability increased as the plastic mixing ratio increased. The stability of the conventional asphalt mixture without any plastic is about 8.4 kN, whereas the stability of the asphalt mixture of the present invention when the plastic mixing ratio is about 18% by weight is About 30 kN. On the other hand, the flow value decreased with increasing asphalt mixing ratio. From the above results, it was confirmed that mixing the plastic increases the strength of the asphalt mixture and decreases the deformation amount.

It is a figure which shows the relationship between the ratio of the plastic in the asphalt mixture shown in Example 2 of this invention, and Marshall stability. It is a figure which shows the relationship between the ratio of the plastic in the asphalt mixture shown in Example 2 of this invention, and a flow value.

Claims (8)

Waste plastics mainly composed of at least one of waste polystyrene, waste polypropylene and waste polyethylene;
With asphalt,
An additive having compatibility with the asphalt and exhibiting high affinity for the waste plastic;
Modified asphalt characterized by including.   The modified asphalt according to claim 1, wherein the additive is waste oil mainly composed of waste engine oil.   The modified asphalt according to claim 1 or 2, wherein the additive is contained in the modified asphalt in an amount of 3 to 9% by weight.   The modified asphalt according to any one of claims 1 to 3, wherein the waste plastic is contained in the modified asphalt in an amount of 10 to 40% by weight. The modified asphalt according to any one of claims 1 to 4,
Aggregate, and
The asphalt mixture, wherein the additive exhibits high affinity with the aggregate.   The asphalt mixture according to claim 5, wherein the additive is a surface modifier that changes the surface of the aggregate from hydrophilic to oleophilic.   The asphalt mixture according to claim 5 or 6, wherein a ratio of the waste plastic in the asphalt mixture is 4 to 18% by weight. A method for producing a modified asphalt containing waste plastic mainly composed of at least one of waste polystyrene, waste polypropylene, and waste polyethylene,
A predetermined amount of waste plastic and an additive that is compatible with asphalt and has high affinity for the waste plastic are stirred and mixed under heating.
A method for producing modified asphalt, which comprises stirring and mixing a mixture of waste plastic and additive melted by stirring and mixing under heating, and asphalt heated to substantially the same temperature as the mixture.

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