Paving mixture and method for producing the same

Abstract

To provide a pavement mixture that prevents careless fixing of pavement mixtures when stored to increase storage properties and workability, and a method for producing the same.SOLUTION: A pavement mixture 10 comprises aggregate 11, and a coating layer 12 that covers the surroundings of the aggregate 11. The coating layer 12 has asphalt that covers the surroundings of the aggregate 11 and porous minerals 16. Therefore, the coating layer 12 including the porous minerals 16 minimizes adhesive strength on the outer surface of the coating layer 12 during storage, thereby making it possible to prevent the pavement mixtures 10 from being fixed to each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to paving mixtures and methods for making the same. [Background technology]

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

[0003] Hot asphalt mix consists of aggregates coated with asphalt heated to high temperatures. During the manufacturing process, the hot asphalt mix is ​​cooled and hardened in individual pieces, allowing it to be stored and then reheated and applied at the construction site. To produce this, the hot asphalt mix is ​​rapidly cooled with water or other means at the end of the manufacturing process, and then dried. During this process, the hot asphalt mix is ​​passed through a mesh or other means and dropped into a cooling layer to prevent the asphalt-covered aggregates from sticking together during cooling. Alternatively, the hot asphalt mix is ​​separated and mixed in the cooling layer.

[0004] Cold mix asphalt is a material that is produced at a lower temperature than heated asphalt mix and stored and applied at room temperature. It consists of aggregate coated with cutback asphalt. Cutback asphalt is made from asphalt with added volatile petroleum, and has the property of softening to a viscosity that can be applied at room temperature. Cold mix asphalt is used for repair, maintenance, and temporary restoration of roads, etc.

[0005] Inventions relating to the above matters are described in the following patent documents. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 2923587 [Patent Document 2] Patent No. 4817085 [Patent Document 3] Patent No. 5916937 [Patent Document 4] Patent No. 6026035 [Patent Document 5] Patent No. 6089139 [Patent Document 6] Patent No. 4896767 Summary of the Invention [Problem to be solved by the invention]

[0007] The inventions according to the background art described above have room for improvement in terms of maintaining the properties of the paving mixture in good condition during storage.

[0008] Specifically, paving mixtures have a problem in that the particles of the mixture tend to stick together during storage, which can cause problems when used in construction. Therefore, measures are taken to prevent the particles of the mixture from sticking together when the paving mixture is produced.

[0009] For example, in the case of existing manufacturing plants, as mentioned above, a water tank may be installed to cool the paving mix. Furthermore, a new facility with a mesh may be installed to individually sift the asphalt-coated aggregate. This allows the hot asphalt-coated paving mix to harden in a separate, individual state. However, these measures require expensive equipment, which raises the problem of high costs.

[0010] In light of the above problems, the object of the present invention is to provide a paving mixture and a method for manufacturing the same that improves preservation and workability by preventing 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 coating layer that covers the periphery of the aggregate, and the coating layer contains asphalt that covers the periphery of the aggregate and a porous mineral.The coating layer contains cutback oil and additives. It is characterized by:

[0012] The method for producing a paving mixture of the present invention includes a first step of mixing aggregate and asphalt to coat the surface of the aggregate with a coating layer made of the asphalt, and a second step of mixing a porous mineral with the coating layer. and a third step of adding cutback oil and additives to the coating layer. It is characterized by: [Effects of the Invention]

[0017] By preventing inadvertent adhesion of the paving mixture to each other during storage, it is possible to provide a paving mixture with improved preservability and workability, and a method for producing the same. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view showing a paving mixture according to an embodiment of the present invention. [Figure 2] 1 is a flowchart showing a method for manufacturing and applying a paving mixture according to an embodiment of the present invention, and cross-sectional views showing the state of the paving mixture in each step. [Figure 3] FIG. 2 is a cross-sectional view showing a paving mixture according to another embodiment of the present invention. [Figure 4] FIG. 1 is a flowchart showing a method for manufacturing and applying a paving mixture according to another embodiment of the present invention, and cross-sectional views showing the state of the paving mixture in each step. [Figure 5A] 1 is a table comparing the formulation of a paving mixture according to a comparative example and an embodiment of the present invention. [Figure 5B] 1 is a table showing the workability of a paving mixture in accordance with an embodiment of the present invention and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0025] A paving mixture 10 according to one embodiment of the present invention and a method for manufacturing the same will be described in detail below with reference to the drawings. In the following description, the same components will generally be designated by the same reference numerals, and repeated explanations will be omitted.

[0026] First Embodiment In the first embodiment, a configuration and manufacturing method of a paving mixture 10 using high-temperature asphalt as a coating layer 12 is described. The asphalt in this embodiment is ordinary asphalt to which cutback oil, which will be described later, has not been added.

[0027] The configuration of paving mixture 10 will be described with reference to Figure 1. Figure 1 is a cross-sectional view showing paving mixture 10. From above, Figure 1 shows a cross-sectional view showing the entire paving mixture 10, a cross-sectional view of an enlarged surface portion of paving mixture 10, and a cross-sectional view of an even further enlarged surface portion of paving mixture 10.

[0028] Referring to FIG. 1, a paving mixture 10 comprises aggregate 11 and a covering layer 12 covering the periphery of the aggregate 11 .

[0029] As will be described later, the paving mixture 10 is configured so that the paving mixture 10 does not easily stick to itself, and therefore can be stored at room temperature for a long period of time, for example, in bags containing several tens of kilograms.

[0030] The aggregate 11 is made of stones or the like adjusted to have a predetermined grain size. The grain size of the aggregate 11 conforms to, for example, the pavement construction manual established by the Japan Road Association. The aggregate 11 is made of crushed stone, sand, or the like.

[0031] The covering layer 12 is a layer that covers the periphery of the aggregate 11. The covering layer 12 serves as a binder that bonds the aggregates together during construction, and contains a filler.

[0032] The filler is mainly made from powdered limestone, which works together with the binder to fill the gaps in the aggregate and improve the stability and durability of the mixture. Fillers are also mixed into general asphalt mixtures.

[0033] In the present invention, all or part of the filler is replaced with a porous mineral. Specifically, the coating layer 12 mainly comprises asphalt that directly covers the aggregate 11 and a porous mineral 16. This prevents the porous mineral 16 from being exposed to the outside from the surface of the coating layer 12, preventing the paving mixture 10 from accidentally adhering to itself.

[0034] As shown in the enlarged view of FIG. 1, the coating layer 12 has, from the inside out, a first coating layer 13 and a second coating layer 14 .

[0035] The first coating layer 13 is a layer that basically does not contain porous minerals 16 and is a layer that is mainly made of asphalt. Even if the first coating layer 13 contains porous minerals 16, the content of the porous minerals 16 in the first coating layer 13 is less than the content of the porous minerals 16 in the second coating layer 14.

[0036] The second coating layer 14 is a layer containing a porous mineral 16, and is a layer mainly composed of asphalt and the porous mineral 16. The content of the porous mineral 16 in the second coating layer 14 is greater than the content of the porous mineral 16 in the first coating layer 13.

[0037] The porous mineral 16 is a foamed and expanded porous mineral. Specifically, the porous mineral 16 can be vermiculite, which is made from magnesia, or perlite, which is made from obsidian, perlite, or rosin. The porous mineral 16 has a larger volume than ordinary fillers (stone powder) at the same weight. This allows for a reduction in the amount of filler used in the coating layer 12, while maintaining the apparent viscosity of the asphalt binder. Furthermore, considering the manufacturing process of the paving mixture 10, only the amount of filler needs to be adjusted. Therefore, when using the present invention to improve an existing product, the paving mixture 10 can be manufactured without significantly changing the aggregate composition.

[0038] The average particle size of the porous mineral 16 is, for example, 15 μm or more and 300 μm or less, and the cake bulk density is 0.3 g / ml or less. By making the average particle size of the porous mineral 16 15 μm or more, the specific surface area of ​​the porous mineral 16 can be made equal to or less than a certain level, the amount of asphalt adsorbed to the porous mineral 16 can be made equal to or less than a certain level, and the adhesion on the surface of the coating layer 12 can be maintained equal to or more than a certain level. By making the average particle size of the porous mineral 16 300 μm or less, the specific surface area of ​​the porous mineral 16 can be made equal to or more than a certain level, and a sufficient amount of asphalt can be retained on the surface of the porous mineral 16.

[0039] Furthermore, when manufacturing the paving mixture 10, additives may be mixed into the coating layer 12 to impart functionality to the paving mixture 10 (e.g., water resistance, resistance to deformation and scattering, drainage, permeability, etc.). In this embodiment, the porous mineral 16 adsorbs the additives. As a result, the additives penetrate into the second coating layer 14, which is the surface layer of the coating layer 12, but are prevented from penetrating into the first coating layer 13, which is the inner portion. As a result, the first coating layer 13, which is a binder layer that is less affected by additives, remains immediately adjacent to the aggregate 11. Because the additives remain in large amounts in the second coating layer 14, which is the surface layer (the surface where the mixture particles adhere to each other), and perform their function, the amount of additives used can be reduced for the paving mixture 10 as a whole.

[0040] Furthermore, the coating layer 12 contains 25% by weight or more and 75% by weight or less of the porous mineral 16 relative to the weight of the asphalt binder. When the weight ratio of the porous mineral 16 to the asphalt is 25% by weight or more, the porous mineral 16 can be sufficiently exposed on the surface of the coating layer 12, and can effectively suppress the adhesive force on the outer surface of the coating layer 12. Furthermore, when the weight ratio of the porous mineral 16 to the asphalt is 75% by weight or less, the basic properties of the asphalt in the coating layer 12 can be sufficiently ensured.

[0041] Referring to the enlarged view at the bottom of Figure 1, a portion of the porous mineral 16 protrudes outward from the outer peripheral surface of the coating layer 12. In this manner, the protruding porous mineral 16 prevents the coating layers 12 of the paving mixture 10 from adhering to each other, thereby preventing the paving mixtures 10 from accidentally adhering to each other. Furthermore, since the second coating layer 14 formed on the outside mainly contains the porous mineral 16, the porous mineral 16 can be concentrated at the outer edge of the coating layer 12, thereby significantly preventing the paving mixtures 10 from adhering to each other.

[0042] A method for producing the paving mixture 10 will be described with reference to Figure 2. Figure 2 is a flowchart showing the method for producing the paving mixture 10, and cross sections of aggregate 11 and the like are shown schematically on the right side of each step.

[0043] The method for producing paving mixture 10 includes a first step of mixing aggregate 11 with asphalt to coat the surface of aggregate 11 with coating layer 12 made of asphalt, and a second step of mixing porous mineral 16 into coating layer 12. Specifically, the method for producing paving mixture 10 includes steps S10 to S15 shown in Figure 2. Here, step S10 is the first step, and step S11 is the second step.

[0044] In step S10, aggregate 11 and asphalt are mixed using factory equipment for producing paving mixture 10. As mentioned above, aggregate 11 can be a mixture of crushed stone, sand, and filler. In practice, aggregate 11 with an appropriately adjusted particle size is dried and heated to an appropriate temperature, and then aggregate 11 of the desired particle size range is added to a mixer, and filler and heated paving petroleum asphalt are added and mixed. In this step, aggregate 11 is used that is as dry as possible, and the drying and heating temperature is adjusted. Furthermore, filler in the room temperature range is added and mixed after asphalt heated to an appropriate temperature is added and mixed. This step results in aggregate 11 whose surface is covered with coating layer 12.

[0045] In step S11, porous mineral 16 is mixed with aggregate 11 and coating layer 12 produced in step S10. Specifically, while the aggregate 11 and coating layer 12 produced in step S10 are being stirred inside the mixer, porous mineral 16 is added to the mixer. Then, inside the mixer, the aggregate 11 coated with coating layer 12 and the porous mineral 16 are mixed. As a result, the porous mineral 16 is attached to a portion of the coating layer 12 near the surface. In other words, the coating layer 12 is formed from a first coating layer 13, which is the inner portion, and a second coating layer 14, which is the outer portion. The first coating layer 13 is a layer that basically does not contain porous mineral 16. The second coating layer 14 is a layer that contains porous mineral 16. Details of the paving mixture 10 are as described with reference to FIG. 1.

[0046] In step S12, the paving mixture 10 produced in step S11 is discharged from the mixer. In this embodiment, steps S10 to S12 are performed in a plant.

[0047] In step S13, the paving mixture 10 produced by the plant is stored. For example, the paving mixture 10 is stored together with the plant in a stockyard or the like set up within the factory. Because the paving mixture 10 according to this embodiment has porous mineral 16 near the surface of the coating layer 12, blocking, in which the paving mixture 10 sticks together, is prevented even if the paving mixture 10 is stored in a stockyard or the like for an extended period of time. Furthermore, the paving mixture 10 hardens individually, and sticking due to temperature drops does not occur.

[0048] 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 containing several tens of kilograms. In this embodiment, the paving mixture 10 discharged in step S12 may be transported without being stored in step S13. As will be described later, the paving mixture 10 contains porous minerals 16, which prevents the paving mixture 10 from sticking together during transportation.

[0049] 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 or the like, heats it, and then compacts it. This causes the coating layers 12 of adjacent paving mixtures 10 to bond together, thereby allowing the paving mixture 10 to develop strength as a whole. As mentioned above, because the paving mixture 10 has porous minerals 16 around it, the individual particles of the paving mixture 10 remain separate until they are heated and compacted. Therefore, a worker can place the paving mixture 10 in a separate state in any location, ensuring a high level of workability for the paving mixture 10.

[0050] The above is a description of the manufacturing of the paving mixture 10 and the construction using the same in the first embodiment.

[0051] Second Embodiment In the second embodiment, a description will be given of the configuration and manufacturing method of a paving mixture 10 using cold asphalt as the coating layer 12. The asphalt in this embodiment is cutback asphalt, which will be described in the next section.

[0052] Cold mix asphalt is a material that is produced at a lower temperature than heated asphalt mix and stored and applied at room temperature. The softening point of asphalt is around 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. In order to soften asphalt at room temperature, volatile petroleum (kerosene, heavy oil, etc.) is sometimes added during production. This volatile petroleum is called cutback oil, and asphalt containing volatile petroleum is called cutback asphalt.

[0053] When producing paving mixture 10, additives 15 may be mixed in to impart functionality (e.g., water resistance, resistance to deformation or scattering, drainage, water permeability, etc.) to paving mixture 10. Specifically, additives 15 may be a volatile solution, a primer-like solution to which a resin or rubber has been added, or a solution produced by a crosslinking reaction, a saponification reaction, an aggregation reaction, or the like.

[0054] The configuration and manufacturing method of the paving mixture 10 according to the second embodiment are basically the same as the configuration and manufacturing method of the paving mixture 10 according to the first embodiment. Therefore, the following description will focus on the differences between the second embodiment and the first embodiment, and will omit and refer to the same parts. In the second embodiment, elements that are the same or similar to those in the first embodiment will be assigned the same or similar reference numerals.

[0055] 3 is a cross-sectional view showing the configuration of a paving mixture 10 according to a second embodiment. Shown here are, from above, 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 an even enlarged cross-sectional view of the vicinity of the surface of the paving mixture 10.

[0056] The paving mixture 10 includes aggregate 11 and a coating layer 12 that coats the surface of the aggregate 11. Here, the coating layer 12 includes, from the inside out, a first coating layer 13 and a second coating layer 14.

[0057] The first coating layer 13 is a layer that covers the surface of the aggregate 11 from the periphery, and is a layer that does not contain porous minerals 16 and is a layer that is mainly made of cutback asphalt. Furthermore, even if the first coating layer 13 contains porous minerals 16, the content of the porous minerals 16 in the first coating layer 13 is less than the content of the porous minerals 16 in the second coating layer 14.

[0058] The second coating layer 14 is a layer that covers the first coating layer 13 from the outside, and is a layer that contains a large amount of porous minerals 16 in order to reduce the adhesive force on the surface of the coating layer 12. Specifically, the content of the porous minerals 16 in the second coating layer 14 is greater than the content of the porous minerals 16 in the first coating layer 13.

[0059] In the second embodiment, the porous mineral 16 contained in the coating layer 12 has a large surface area and is absorbent, so it absorbs excess cutback oil contained in the cutback asphalt. This prevents the asphalt from softening too much compared to ordinary cold asphalt mixtures, and the frictional resistance between the aggregates 11 after construction is not impaired, adhesive strength is maintained, and the asphalt has higher stability than in the initial stages of construction. In addition, by absorbing excess cutback oil, it is possible to prevent the runoff of cutback oil during rainfall, which was a problem in conventional construction.

[0060] 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 (e.g., water resistance, resistance to deformation and scattering, drainage, permeability, etc.). In this embodiment, the porous mineral 16 adsorbs the additives 15. As a result, the additives 15 penetrate into the second coating layer 14, which is the surface layer of the coating layer 12, but are prevented from penetrating into the first coating layer 13, which is the inner portion. As a result, the first coating layer 13, which is a binder layer that is less affected by the additives 15, remains immediately adjacent to the aggregate 11. Because the additives 15 remain in large amounts in the second coating layer 14, which is the surface layer (the surface where the mixture particles adhere to each other), and perform their function, the amount of additives 15 used can be reduced for the paving mixture 10 as a whole.

[0061] The weight of the cutback oil or additive added to the coating layer 12 is 5% by weight to 25% by weight of the asphalt. By doing so, 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 paving mixture 10 can be prevented from accidentally adhering to each other.

[0062] 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 herein includes steps S10 through S16. Here, the paving mixture 10 produced in step S11 can be considered an intermediate product before the additives are added in step S14. Steps S10 or S11 may also be referred to as primary mixing, and step S14 as secondary mixing.

[0063] Steps S10 to S13 shown in Fig. 4 are the same as steps S10 to S13 shown in Fig. 2. Here, step S14 corresponds to the third step of adding an additive to the coating layer 12. Also, in step S10 shown in Fig. 4, aggregate 11 and cutback asphalt are mixed.

[0064] In step S14, additive 15 is added to aggregate 11 coated with coating layer 12. Specifically, additive 15 is added while aggregate 11 coated with coating layer 12 is being mixed inside a mixer. Details of additive 15 are as described above.

[0065] In this case, additive 15 is added to second coating layer 14 of coating layer 12. A small amount of additive 15 is also added to first coating layer 13. Here, additive 15 is mainly added to second coating layer 14, which is the surface layer of coating layer 12, so the amount of additive 15 used can be half or less compared to when additive 15 is added to the entire coating layer 12.

[0066] Here, step S14 can be executed at a different timing, for example, step S14 can be executed simultaneously with step S10, which is the primary mixing.

[0067] Step S15 is a process of transporting the paving mixture 10, and is similar to step S14 shown in FIG.

[0068] In step S16, the paving mixture 10 is used for construction. One example of the paving mixture 10 is used for road repair. For example, a worker spreads the paving mixture 10 over an area of ​​a road or other structure that requires repair, and then compacts it. This causes the coating layers 12 of adjacent paving mixtures 10 to bond together, thereby increasing the overall strength of the paving mixture 10. As mentioned above, because the paving mixture 10 contains porous minerals 16 around it, the individual particles of the paving mixture 10 remain separate until compaction is performed. Therefore, a worker can place the paving mixture 10 in a separate state in the area to be repaired, ensuring a high level of workability for the paving mixture 10.

[0069] The above is a description of the production of the paving mixture 10 and the construction using the same in the second embodiment.

[0070] Third Embodiment In the third embodiment, the mix proportions, application state, strength, etc. of the paving mixture 10 will be described.

[0071] 5A is a table comparing the formulation of the paving mixture 10 according to the present embodiment with that of a comparative example. Here, the primary mixing refers to the process up to mixing asphalt with aggregate 11. The secondary mixing refers to the process up to mixing additives.

[0072] The comparative example of the primary mixture contains 66.0% by weight of No. 7 crushed stone as aggregate and 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 asphalt with additives as binder.

[0073] The primary mix of the paving mixture 10 according to this embodiment contains 56.0% by weight of No. 7 crushed stone and 32.9% by weight of sand as aggregate 11. Additionally, the paving mixture 10 contains 2.7% by weight of perlite as a porous mineral 16, replacing the filler. Additionally, the paving mixture 10 contains 5.7% by weight of straight asphalt as a binder.

[0074] In the secondary mixing, the paving mixture 10 according to this embodiment contains 2.7% by weight of additives.

[0075] In both the comparative example and the example, the maximum crushed stone particle size was 5 mm (No. 7 crushed stone), making it an all-weather mixture suitable for wet repair surfaces. The comparative example was manufactured by mixing crushed stone, sand, binder, and stone powder as a filler. On the other hand, the paving mixture 10 of this embodiment was manufactured by replacing the stone powder with porous mineral 16 (perlite in the example). Although the amount of filler material used in the paving mixture 10 of the example was reduced to less than half, there were no problems with manufacturing or construction, and it can be said that the mixture fulfilled its required functions.

[0076] FIG. 5B is a table comparing the comparative example and the paving mixture 10 according to this embodiment from the viewpoint of the appearance during construction and the strength of the laid object.

[0077] First, the workability of the mixture will be compared.

[0078] In the bagged state, the comparative example felt somewhat hard from the top of the bag and required loosening of clumps when removed from the bag, whereas the paving mixture 10 was easy to move from the top of the bag and could be applied as is.

[0079] When spreading, the comparative example required loosening of lumps and oil adhered to the tools, whereas the paving mixture 10 could be spread smoothly and did not adhere to the tools.

[0080] Furthermore, when water was sprayed strongly from a hose after application in anticipation of heavy rain, the comparative example caused some oil to flow out and even particles to come off at the edges. On the other hand, the paving mixture 10 did not cause any oil to flow out and the edges maintained their shape.

[0081] In addition, a Marshall stability test was conducted to verify the stability when submerged. In the comparative example, the shape of the test specimen was not formed, making it impossible to measure. On the other hand, the paving mixture 10 had a strength of 3.1 kN immediately after submersion and 12.0 kN after 24 hours, demonstrating sufficient stability.

[0082] The paving mixture 10 absorbs cutback oil due to the mineral properties of its porous structure. This prevents excessive leaching of cutback oil throughout the entire construction mixture. This means that there is almost no oil adhering to tools during construction or spillage onto the water surface during watering. The adhesive strength is also maintained to the extent that the edges do not loosen, which has a positive effect on construction.

[0083] Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and can be modified within the scope of the object and spirit of the present invention. The invention that can be understood from the above-described embodiment will be described below together with its effects. The paving mixture of the present invention comprises aggregate and a coating layer covering the periphery of the aggregate, the coating layer comprising asphalt covering the periphery of the aggregate and a porous mineral. According to the present invention, the inclusion of the porous mineral in the coating layer reduces the adhesive strength of the outer surface of the coating layer during storage, thereby preventing the paving mixture from sticking together. In addition, in the paving mixture of the present invention, the coating layer has, from the inside, a first coating layer and a second coating layer, the first coating layer does not contain the porous mineral, and the second coating layer contains the porous mineral. According to the present invention, since only the second coating layer formed on the outside contains the porous mineral, the porous mineral can be gathered at the outer edge of the coating layer, and the effect of suppressing adhesion between paving mixtures can be remarkable. In addition, in the paving mixture of the present invention, the porous mineral has an average particle size of 15 μm to 300 μm and a cake bulk density of 0.3 g / ml or less. By setting the average particle size and cake bulk density of the porous mineral within these ranges, the properties of the coating layer can be determined as desired. Furthermore, in the paving mixture of the present invention, the coating layer is characterized by containing 25% by weight or more and 75% by weight or less of the porous mineral relative to the weight of the asphalt. According to the present invention, when the weight ratio of the porous mineral to the asphalt is 25% by weight or more, the porous mineral can be sufficiently exposed on the surface of the coating layer, thereby achieving the effect of suppressing the adhesive strength of the outer surface of the coating layer. Furthermore, when the weight ratio of the porous mineral to the asphalt is 75% by weight or less, the basic properties of the asphalt in the coating layer can be sufficiently ensured. In addition, in the paving mixture of the present invention, the coating layer contains cutback oil and additives. According to the present invention, even when the asphalt is cutback asphalt, the adhesive strength of the outer surface of the coating layer is suppressed during storage, and sticking of the paving mixture to each other can be suppressed. The method for producing a paving mixture of the present invention comprises a first step of mixing aggregate with asphalt to coat the surface of the aggregate with a coating layer made of the asphalt, and a second step of mixing a porous mineral into the coating layer. According to the present invention, by including a porous mineral in the coating layer, the adhesive strength of the outer surface of the coating layer during storage can be reduced, and the paving mixture can be prevented from sticking together. The method for producing a paving mixture of the present invention further comprises 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 the porous mineral, thereby reducing the adhesive strength of the outer surface of the coating layer during storage and preventing the paving mixture from sticking together. [Explanation of symbols]

[0084] 10 Paving Mix 11 Aggregate 12 Covering layer 13 First coating layer 14 Second coating layer 15 Additives 16 Porous Minerals

Claims

1. The method comprises: providing an aggregate; and providing a coating layer that covers the aggregate; The coating layer includes asphalt that coats the periphery of the aggregate and a porous mineral, The coating layer comprises cutback oil and an additive.

2. The coating layer has, from the inside, a first coating layer and a second coating layer, the first coating layer does not contain the porous mineral; 2. The paving mixture of claim 1, wherein the second coating layer comprises the porous mineral.

3. 2. The paving mixture according to claim 1, wherein the porous mineral has an average particle size of 15 μm or more and 300 μm or less, and a cake bulk density of 0.3 g / ml or less.

4. 2. The paving mixture according to claim 1, wherein the coating layer contains 25% by weight or more and 75% by weight or less of the porous mineral relative to the weight of the asphalt.

5. A first step of mixing aggregate and asphalt to coat the surface of the aggregate with a coating layer made of the asphalt; a second step of mixing a porous mineral into the coating layer; and a third step of adding cutback oil and additives to the coating layer.

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