Paving mixture and method for producing the same

Abstract

This invention provides a paving mixture and a method for producing the same, which improves storability and workability by preventing unintentional adhesion between paving mixtures during storage. [Solution] The paving mixture 10 comprises aggregate 11 and a covering layer 12 that covers the aggregate 11. The covering layer 12 has asphalt covering the aggregate 11 and porous minerals 16. Therefore, by including porous minerals 16 in the covering layer 12, the adhesive force on the outer surface of the covering layer 12 is suppressed during storage, and the paving mixture 10 can be prevented from sticking together.

Description

Technical Field

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[0001] The present invention relates to a paving mixture and a method for producing the same.

Background Art

[0002] Paving mixtures can be broadly classified into hot asphalt mixtures and cold asphalt mixtures.

[0003] Hot asphalt mixtures are composed of aggregates coated with asphalt heated to a high temperature. In the manufacturing process, some hot asphalt mixtures are cooled and cured in an individual, separate state for storage, and then reheated at the construction site for construction. To manufacture this, at the end of the manufacturing process, the hot asphalt mixture is rapidly cooled with water or the like, and then the hot asphalt mixture is dried. At this time, the hot asphalt mixture is dropped onto a cooling layer through a net or the like so that the aggregates coated with asphalt do not stick to each other during cooling. Alternatively, the hot asphalt mixture is separated and stirred in the cooling layer.

[0004] Cold asphalt mixtures are materials manufactured at a lower temperature than hot asphalt mixtures and stored and constructed at room temperature, and are composed of aggregates coated with cutback asphalt. Cutback asphalt is composed of asphalt to which volatile petroleum has been added and has the property of softening to a viscosity that can be constructed at room temperature. Cold asphalt mixtures are used for road repair, maintenance, and temporary restoration.

[0005] Inventions related to the above matters are described in the following patent documents.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

[0007] The aforementioned invention relating to the background technology had room for improvement in terms of maintaining the properties of the paving mixture well during storage.

[0008] Specifically, a problem with paving mixtures was that they would stick together during storage, hindering construction work using the mixtures. Therefore, measures are being taken to suppress the sticking of paving mixtures during the manufacturing process.

[0009] For example, in the case of existing manufacturing plants, as mentioned above, a water tank may be installed to cool the paving mixture. Furthermore, there is also the measure of installing new equipment with a mesh to sieve the asphalt-coated aggregate individually. In this way, the high-temperature asphalt-coated paving mixture can be hardened in a separated state. However, these measures require expensive equipment, which leads to increased costs.

[0010] The objective of the present invention, based on the above-mentioned problems, is to provide a paving mixture and a method for producing the same that improves storability and workability by suppressing the inadvertent adhesion of paving mixtures to each other during storage. [Means for solving the problem]

[0011] The paving mixture of the present invention comprises aggregate and a covering layer that covers the aggregate, wherein the covering layer comprises asphalt that covers the aggregate and porous minerals. [Effects of the Invention]

[0012] The paving mixture of the present invention comprises aggregate and a covering layer that covers the aggregate, wherein the covering layer comprises asphalt covering the aggregate and porous minerals. According to the present invention, the inclusion of porous minerals in the covering layer suppresses the adhesive force on the outer surface of the covering layer during storage, thereby preventing the paving mixtures from sticking together. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view showing a paving mixture according to an embodiment of the present invention. [Figure 2] This is a flowchart illustrating a method for manufacturing and constructing a paving mixture according to an embodiment of the present invention, and a cross-sectional view showing the state of the paving mixture at each step. [Figure 3] This is a cross-sectional view showing a paving mixture according to another embodiment of the present invention. [Figure 4] This is a flowchart illustrating a method for manufacturing and constructing a paving mixture according to another embodiment of the present invention, and a cross-sectional view showing the state of the paving mixture at each step. [Figure 5A] This table compares the formulation of a comparative example with the paving mixture according to this embodiment of the present invention. [Figure 5B] This table shows the workability of the paving mixture and its manufacturing method according to an embodiment of the present invention. [Modes for carrying out the invention]

[0014] The paving mixture 10 and its manufacturing method according to one embodiment of the present invention will be described in detail below with reference to the drawings. In the following description, the same reference number will be used for identical components as a general rule, and repeated explanations will be omitted.

[0015] <First Embodiment> In the first embodiment, the configuration and manufacturing method of the paving mixture 10 using high-temperature asphalt as the coating layer 12 will be described. The asphalt in this embodiment is ordinary asphalt to which the cutback oil described later is not added.

[0016] Referring to FIG. 1, the configuration of the paving mixture 10 will be described. FIG. 1 is a cross-sectional view showing the paving mixture 10. In FIG. 1, from above, a cross-sectional view showing the entire paving mixture 10, a magnified cross-sectional view of the surface portion of the paving mixture 10, and a further magnified cross-sectional view of the surface portion of the paving mixture 10 are shown.

[0017] Referring to FIG. 1, the paving mixture 10 includes an aggregate 11 and a coating layer 12 that coats the periphery of the aggregate 11.

[0018] As will be described later, the paving mixture 10 has a structure in which it is difficult for the paving mixtures 10 to stick to each other. Therefore, for example, it can be stored at room temperature for a long period of time in a bagged state every several tens of kg. <0OO0099>

[0019] The aggregate 11 is made of stones or the like adjusted to have a predetermined particle size. The particle size of the aggregate 11 shall conform to, for example, the Paving Construction Manual established by the Japan Road Association. The aggregate 11 is made of crushed stones, sand, etc.

[0020] The coating layer 12 is a layer that coats the periphery of the aggregate 11. The coating layer 12 serves as a binder that adheres the aggregates to each other during construction and contains a filler. [[ID=2H]]

[0021] The filler is mainly stone powder obtained by pulverizing limestone. It integrates with the binder to fill the gaps between the aggregates and has the role of improving the stability and durability of the mixture. Fillers are also mixed in general asphalt mixtures.

[0022] In this invention, all or part of the filler is replaced with porous minerals. Specifically, the coating layer 12 mainly consists of asphalt that directly covers the aggregate 11 and porous minerals 16. As a result, the porous minerals 16 are exposed to the outside from the surface of the coating layer 12, and the inadvertent adhesion of the paving mixture 10 to each other is suppressed.

[0023] As shown in the enlarged view of Figure 1, the coating layer 12 has a first coating layer 13 and a second coating layer 14 from the inside.

[0024] The first coating layer 13 is a layer that basically does not contain porous minerals 16 and is mainly composed of asphalt. Furthermore, even if the first coating layer 13 contains porous minerals 16, the content of porous minerals 16 in the first coating layer 13 is less than the content of porous minerals 16 in the second coating layer 14.

[0025] The second coating layer 14 is a layer containing porous minerals 16, and is mainly composed of asphalt and porous minerals 16. The content of porous minerals 16 in the second coating layer 14 is greater than the content of porous minerals 16 in the first coating layer 13.

[0026] As the porous mineral 16, a porous structure mineral that has been expanded through foaming is used. Specifically, as the porous mineral 16, vermiculite made from magnesium vermiculite, or perlite made from obsidian, perlite, or pitchstone can be used. The porous mineral 16 has a larger volume than ordinary filler (stone powder) for the same weight. Therefore, the amount of filler used in the coating layer 12 can be reduced, and even with the reduction, the apparent viscosity of the asphalt binder can be maintained. Furthermore, considering the manufacturing process of the paving mixture 10, only the amount of filler needs to be adjusted, so for example, when using the present invention to improve an existing product, the paving mixture 10 can be manufactured without significantly changing the aggregate composition.

[0027] The average particle size of the porous mineral 16 is, for example, 15 μm to 300 μm, and the cake bulk density is 0.3 g / ml or less. By setting the average particle size of the porous mineral 16 to 15 μm or more, the specific surface area of ​​the porous mineral 16 can be kept below a certain level, the amount of asphalt adsorbed on the porous mineral 16 can be kept below a certain level, and the tackiness on the surface of the coating layer 12 can be maintained above a certain level. By setting the average particle size of the porous mineral 16 to 300 μm or less, the specific surface area of ​​the porous mineral 16 can be kept above a certain level, and a sufficient amount of asphalt can be retained on the surface of the porous mineral 16.

[0028] Furthermore, when manufacturing the paving mixture 10, additives may be mixed into the coating layer 12 to impart functionality to the paving mixture 10 (for example, water resistance, resistance to deformation and scattering, drainage, water permeability, etc.). In this embodiment, the porous mineral 16 adsorbs the additives. Therefore, the additives penetrate into the second coating layer 14, which is the surface layer of the coating layer 12, but the penetration of the additives into the first coating layer 13, which is the inner part, is suppressed. As a result, the first coating layer 13, which is a binder layer with less influence from the additives, remains in close proximity to the aggregate 11. Since the additives remain mostly in the second coating layer 14, which is the surface layer (the surface where the particles of the mixture adhere to each other), and exert their function there, the total amount of additives used in the paving mixture 10 can be reduced.

[0029] Furthermore, the coating layer 12 contains porous minerals 16 in an amount of 25% to 75% by weight relative to the weight of the binder, asphalt. A weight ratio of 25% or more of porous minerals 16 to asphalt allows the porous minerals 16 to sufficiently appear on the surface of the coating layer 12, thereby suppressing the adhesive force on the outer surface of the coating layer 12. Additionally, a weight ratio of 75% or less of porous minerals 16 to asphalt ensures that the basic properties of the asphalt in the coating layer 12 are sufficiently maintained.

[0030] Referring to the enlarged view at the bottom of Figure 1, a portion of the porous minerals 16 protrudes outward from the outer surface of the coating layer 12. In this way, the protruding portions of the porous minerals 16 suppress the adhesion between the coating layers 12 of the paving mixture 10, thereby suppressing the inadvertent adhesion of the paving mixture 10 to each other. Furthermore, since the second coating layer 14 formed on the outside mainly contains porous minerals 16, the porous minerals 16 can be gathered at the outer edge of the coating layer 12, significantly enhancing the effect of suppressing the adhesion of the paving mixture 10 to each other.

[0031] Referring to Figure 2, the method for producing the paving mixture 10 described above will be explained. Figure 2 is a flowchart showing the method for producing the paving mixture 10, and the right side of each step schematically shows the cross-section of the aggregate 11, etc.

[0032] The method for producing the paving mixture 10 comprises a first step of mixing aggregate 11 with asphalt to cover the surface of the aggregate 11 with a coating layer 12 made of asphalt, and a second step of mixing porous minerals 16 into the coating layer 12. Specifically, the method for producing the paving mixture 10 has steps S10 to S15 as shown in Figure 2. Here, step S10 is the first step and step S11 is the second step.

[0033] In step S10, aggregate 11 and asphalt are mixed using factory equipment for manufacturing the paving mixture 10. As described above, a mixture of crushed stone, sand, and filler can be used as the aggregate 11. In practice, aggregate 11 of an appropriate particle size is dried and heated to a suitable temperature, then aggregate 11 within the desired particle size range is put into a mixer, and filler and heated paving petroleum asphalt are added and mixed. In this step, aggregate 11 that is as dry as possible is used, the drying and heating temperature is adjusted, and filler that is in the room temperature range is added and mixed after the asphalt heated to a suitable temperature is added and mixed. Through this step, aggregate 11 with a surface covered with a coating layer 12 is obtained.

[0034] In step S11, porous minerals 16 are mixed with the aggregate 11 and coating layer 12 produced in step S10. Specifically, the porous minerals 16 are added to the mixer while the aggregate 11 and coating layer 12 produced in step S10 are stirred inside the mixer. As a result, the aggregate 11 covered by the coating layer 12 and the porous minerals 16 are mixed inside the mixer. Consequently, the porous minerals 16 adhere to the surface portion of the coating layer 12. In other words, the coating layer 12 is formed from an inner first coating layer 13 and an outer second coating layer 14. The first coating layer 13 is a layer that does not basically contain porous minerals 16. The second coating layer 14 is a layer that contains porous minerals 16. Details of the paving mixture 10 are as described with reference to Figure 1.

[0035] In step S12, the paving mixture 10 generated in step S11 is discharged from the mixer. In this embodiment, steps S10 to S12 are performed in a plant.

[0036] In step S13, the paving mixture 10 manufactured by the plant is stored. For example, the paving mixture 10 is stored in a stockyard or the like, which is located within the factory along with the plant. In this embodiment, since the paving mixture 10 has porous minerals 16 near the surface of the coating layer 12, even if the paving mixture 10 is stored in a stockyard or the like for a long period of time, blocking, where the paving mixtures 10 stick together, is suppressed. In addition, the paving mixtures 10 harden individually and do not stick together due to temperature drops.

[0037] In step S14, the paving mixture 10 stored in a stockyard or the like is transported to the construction site. For example, it is transported in bags of several tens of kilograms each. In this embodiment, however, the paving mixture 10 discharged in step S12 may be transported without the storage in step S13. As will be described later, since the paving mixture 10 has porous minerals 16, the paving mixture 10 is prevented from sticking together during transport.

[0038] In step S15, the paving mixture 10 is used for construction. The paving mixture 10 is used, for example, for laying or repairing roads. For example, a worker spreads the paving mixture 10 on a road, heats it, and then compacts it. In this way, the covering layers 12 of adjacent paving mixtures 10 become integrated, and the paving mixture 10 as a whole develops strength. As mentioned above, since the paving mixture 10 has porous minerals 16 around it, the paving mixture 10 is in a state where the individual particles are separated until it is heated and compacted. Therefore, a worker can place the paving mixture 10 in a separated state in any location, so the workability of the paving mixture 10 is ensured at a high level.

[0039] The above is a description of the manufacturing of the paving mixture 10 and the construction using it in the first embodiment.

[0040] <Second Embodiment> In the second embodiment, the composition and manufacturing method of a paving mixture 10 using cold asphalt as the covering layer 12 will be described. The asphalt in this embodiment is cutback asphalt, which will be described in the next section.

[0041] Room-temperature asphalt mixtures are manufactured at lower temperatures than heated asphalt mixtures and are stored and applied at room temperature. The softening point of asphalt is approximately 40°C to 55°C, and if the binder consists only of asphalt, the entire mixture will solidify at room temperature, making storage and application difficult. To soften the asphalt at room temperature, volatile petroleum (such as kerosene or heavy oil) is sometimes added during manufacturing. This volatile petroleum is called cutback oil, and asphalt containing volatile petroleum is called cutback asphalt.

[0042] When manufacturing the paving mixture 10, additives 15 may be mixed in to impart functionality (for example, water resistance, resistance to deformation and scattering, drainage, water permeability, etc.) to the paving mixture 10. Specifically, the additives 15 can be volatile solutions, primer-like solutions with added resins or rubbers, or solutions produced by crosslinking reactions, saponification reactions, agglomeration reactions, etc.

[0043] The composition and manufacturing method of the paving mixture 10 according to the second embodiment are basically the same as those of the paving mixture 10 according to the first embodiment. Therefore, in the following description, the second embodiment will focus on the parts that differ from the first embodiment, and the descriptions of similar parts will be omitted and referenced. In the second embodiment, elements that are the same or similar as in the first embodiment will be assigned the same or similar reference numbers.

[0044] Figure 3 is a cross-sectional view showing the structure of the paving mixture 10 according to the second embodiment. Here, from top to bottom, we see an overall view of the paving mixture 10, an enlarged cross-sectional view of the vicinity of the surface of the paving mixture 10, and a further enlarged cross-sectional view of the vicinity of the surface of the paving mixture 10.

[0045] The paving mixture 10 includes aggregate 11 and a coating layer 12 that covers the surface of the aggregate 11. Here, the coating layer 12 includes a first coating layer 13 and a second coating layer 14 from the inside.

[0046] The first coating layer 13 is a layer that covers the surface of the aggregate 11 from the outside, and is a layer that does not contain porous minerals 16, and is mainly composed of cutback asphalt. Furthermore, even if the first coating layer 13 contains porous minerals 16, the content of porous minerals 16 in the first coating layer 13 is less than the content of porous minerals 16 in the second coating layer 14.

[0047] The second coating layer 14 is a layer that covers the first coating layer 13 from the outside and is a layer that contains many porous minerals 16 in order to reduce the adhesive force on the surface of the coating layer 12. Specifically, the content of porous minerals 16 in the second coating layer 14 is greater than the content of porous minerals 16 in the first coating layer 13.

[0048] In the second embodiment, the porous minerals 16 contained in the coating layer 12 have a large surface area and adsorption properties, and adsorb excess cutback oil contained in the cutback asphalt. As a result, the asphalt does not soften excessively compared to ordinary room-temperature asphalt mixtures, the frictional resistance between aggregates 11 after construction is not impaired, and the adhesive strength is maintained, resulting in higher stability from the initial stages of construction. Furthermore, by adsorbing excess cutback oil, it is possible to suppress the outflow of cutback oil during rainfall, which was a problem in conventional construction.

[0049] Furthermore, when manufacturing the paving mixture 10, additives 15 may be mixed into the coating layer 12 to impart functionality to the paving mixture 10 (for example, water resistance, resistance to deformation and scattering, drainage, water permeability, etc.). In this embodiment, the porous mineral 16 adsorbs the additive 15. Therefore, the additive 15 penetrates into the second coating layer 14, which is the surface layer of the coating layer 12, but the penetration of the additive 15 into the first coating layer 13, which is the inner part, is suppressed. As a result, the first coating layer 13, which is a binder layer less affected by the additive 15, remains in close proximity to the aggregate 11. Since the additive 15 remains largely in the second coating layer 14, which is the surface layer (the surface where the particles of the mixture adhere to each other), and exerts its function there, the total amount of additive 15 used in the paving mixture 10 can be reduced.

[0050] Here, the weight of the cutback oil or additive added to the coating layer 12 is 5% by weight or more and 25% by weight or less relative to the weight of the asphalt. In this way, even if the coating layer 12 is a layer containing cutback asphalt, the adhesive force on the outer surface of the coating layer 12 is suppressed during storage, and the inadvertent adhesion of the paving mixture 10 to each other can be suppressed.

[0051] Referring to Figure 4, a method for producing the paving mixture 10 having the configuration shown in Figure 3 will be described. The method for producing the paving mixture 10 here includes steps S10 to S16. Here, the paving mixture 10 produced in step S11 can be considered an intermediate before the additives are added in step S14. Step S10 or step S11 may also be referred to as primary mixing, and step S14 as secondary mixing.

[0052] Steps S10 to S13 shown in Figure 4 are the same as steps S10 to S13 shown in Figure 2. Here, the third step of adding additives to the coating layer 12 corresponds to step S14. Also, in step S10 shown in Figure 4, the aggregate 11 and cutback asphalt are mixed.

[0053] In step S14, the additive 15 is added to the aggregate 11 covered with the coating layer 12. Specifically, the additive 15 is added while the aggregate 11 covered with the coating layer 12 is mixed inside the mixer. Details of the additive 15 are as described above.

[0054] As a result, the additive 15 is added to the second coating layer 14 of the coating layer 12. A small amount of the additive 15 is also added to the first coating layer 13. Here, since the additive 15 is mainly added to the second coating layer 14, which is the surface layer of the coating layer 12, the amount of additive 15 used can be reduced to less than half compared to when it is added to the entire coating layer 12.

[0055] Here, step S14 can be performed at different times. For example, step S14 can be performed simultaneously with step S10, which is a primary mixing step.

[0056] Step S15 is the process of transporting the paving mixture 10, and is the same as step S14 shown in Figure 2.

[0057] In step S16, the paving mixture 10 is used for construction. The paving mixture 10 is used, for example, for road repair. For example, a worker spreads and compacts the paving mixture 10 over the area of ​​a road or other surface that needs repair. In this way, the covering layers 12 of adjacent paving mixtures 10 become integrated, and the paving mixture 10 as a whole develops strength. As mentioned above, since the paving mixture 10 has porous minerals 16 around it, the individual particles of the paving mixture 10 are in a separate state until compaction is performed. Therefore, since a worker can place the paving mixture 10 in a separate state at the place that needs repair, the workability of the paving mixture 10 is ensured at a high level.

[0058] The above is a description of the manufacturing of the paving mixture 10 and the construction using it in the second embodiment.

[0059] <Third Embodiment> In the third embodiment, the composition, construction conditions, and strength of the paving mixture 10 will be described.

[0060] Figure 5A is a table comparing the formulation of a comparative example with the paving mixture 10 according to this embodiment. Here, primary mixing refers to the process up to mixing the aggregate 11 with asphalt. Secondary mixing refers to the process up to mixing in the additives.

[0061] The comparative example of the primary mixture contains 66.0% by weight of No. 7 crushed stone as aggregate, and further contains 22.2% by weight of sand. Furthermore, the comparative example contains 6.8% by weight of stone powder as filler and 5.0% by weight of additive-containing asphalt as binder.

[0062] The paving mixture 10 according to this embodiment of primary mixing contains 56.0% by weight of No. 7 crushed stone and 32.9% by weight of sand as aggregate 11. Furthermore, the paving mixture 10 contains 2.7% by weight of perlite as porous mineral 16 as a filler replacement. Furthermore, the paving mixture 10 contains 5.7% by weight of straight asphalt as a binder.

[0063] In the secondary mixing, the paving mixture 10 according to this embodiment contains 2.7% by weight of additives.

[0064] In both the comparative example and the example, the maximum particle size of the crushed stone is 5 mm (No. 7 crushed stone), and it is an all-weather type mixture that can be used on damp repair surfaces. The comparative example is manufactured by mixing crushed stone, sand, a binder, and stone powder as a filler. On the other hand, the paving mixture 10 of this embodiment is manufactured by replacing the stone powder with a porous mineral 16 (perlite in the example). Although the amount of filler material used in the paving mixture 10 of the example is reduced to less than half, there are no problems in manufacturing or construction, and it can be said that it fulfills the functions required of a mixture.

[0065] Figure 5B is a table comparing the comparative example with the paving mixture 10 according to this embodiment in terms of the construction process and the strength of the laid material.

[0066] First, we will compare the mixtures from the perspective of their workability.

[0067] In its bagged state, the comparative example has a somewhat hard feel from the outside of the bag, and it is necessary to break up the clumps once it is removed from the bag. On the other hand, the paving mixture 10 can be easily moved from the outside of the bag, and can be used for construction as is once it is removed from the bag.

[0068] During the spreading process, the comparative example requires breaking up clumps, resulting in oil adhering to the tools. On the other hand, the paving mixture 10 can be spread smoothly without any adhesion to the tools.

[0069] Furthermore, simulating heavy rainfall, when water was strongly applied with a hose after construction, the comparative example showed some oil leakage, and the particles at the edges also came off. On the other hand, paving mixture 10 showed no oil leakage, and the edges maintained their shape.

[0070] Furthermore, a Marshall stability test was conducted to verify the stability under water immersion. In the comparative example, the specimen did not form a shape and therefore could not be measured. On the other hand, paving mixture 10 showed sufficient stability, with a value of 3.1 kN immediately after immersion and 12.0 kN after 24 hours.

[0071] The paving mixture 10 adsorbs cutback oil due to the properties of its porous mineral structure. Therefore, excessive leaching of cutback oil is suppressed throughout the mixture being applied. As a result, there is almost no oil residue on tools during spreading or oil leakage onto the water surface during watering, and sufficient tackiness is maintained so that the edges do not loosen, which is thought to have a positive effect on workability.

[0072] Although embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be modified without departing from the object and spirit of the present invention.

[0073] The inventions that can be understood from the embodiments described above, along with their effects, are described below.

[0074] The paving mixture of the present invention comprises aggregate and a covering layer that covers the aggregate, wherein the covering layer comprises asphalt covering the aggregate and porous minerals. According to the present invention, the inclusion of porous minerals in the covering layer suppresses the adhesive force on the outer surface of the covering layer during storage, thereby preventing the paving mixtures from sticking together.

[0075] Furthermore, in the paving mixture of the present invention, the coating layer comprises a first coating layer and a second coating layer from the inside, wherein the first coating layer does not contain the porous mineral, and the second coating layer contains the porous mineral. According to the present invention, by having only the second coating layer formed on the outside contain the porous mineral, the porous mineral can be aggregated at the outer edge of the coating layer, and the effect of suppressing adhesion between paving mixtures can be significantly enhanced.

[0076] Furthermore, the paving mixture of the present invention is characterized in that the porous mineral has an average particle diameter of 15 μm or more and 300 μm or less, and a cake bulk density of 0.3 g / ml or less. According to the present invention, by setting the average particle diameter and cake bulk density of the porous mineral within these ranges, the properties of the coating layer can be determined.

[0077] Furthermore, in the paving mixture of the present invention, the coating layer is characterized in that it contains the porous mineral in an amount of 25% to 75% by weight relative to the weight of the asphalt. According to the present invention, by having a weight ratio of porous mineral to asphalt of 25% by weight or more, the porous mineral can sufficiently appear on the surface of the coating layer, and the effect of suppressing the adhesive force on the outer surface of the coating layer can be achieved. In addition, by having a weight ratio of porous mineral to asphalt of 75% by weight or less, the basic properties of the asphalt in the coating layer can be sufficiently ensured.

[0078] Furthermore, the paving mixture of the present invention is characterized in that the coating layer contains cutback oil and additives. According to the present invention, even when the asphalt is cutback asphalt, the adhesive force on the outer surface of the coating layer is suppressed during storage, and the adhesion of the paving mixtures to each other can be suppressed.

[0079] Furthermore, the present invention provides a method for producing a paving mixture, comprising: a first step of mixing aggregate and asphalt to cover the surface of the aggregate with a coating layer made of asphalt; and a second step of mixing porous minerals into the coating layer. According to the present invention, by including porous minerals in the coating layer, the adhesive force on the outer surface of the coating layer during storage can be suppressed, and the paving mixtures can be prevented from sticking together.

[0080] Furthermore, the method for producing the paving mixture of the present invention is characterized by further comprising a third step of adding cutback oil and additives to the coating layer. According to the present invention, excess cutback oil and additives are adsorbed by porous minerals, thereby suppressing the adhesive force on the outer surface of the coating layer during storage and preventing the paving mixtures from sticking together. [Explanation of symbols]

[0081] 10 Paving mixtures 11 Aggregates 12 Covering layer 13 First coating layer 14 Second coating layer 15 Additives 16 Porous Minerals

Claims

1. It comprises aggregate and a covering layer that covers the periphery of the aggregate, The paving mixture is characterized in that the covering layer comprises asphalt covering the aggregate and porous minerals.

2. The paving mixture according to claim 1, characterized in that the coating layer contains high-temperature asphalt.

3. The paving mixture according to claim 1, characterized in that the asphalt does not have cutback oil added.

4. The paving mixture according to claim 1, characterized in that the asphalt includes high-temperature asphalt used in a heated state during manufacturing.

5. The first step involves mixing aggregate and asphalt to cover the surface of the aggregate with a coating layer made of asphalt, A method for producing a paving mixture, comprising a second step of mixing porous minerals into the aforementioned coating layer.

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