Slurry-like tack coat material and method for constructing asphalt pavement using the same

Abstract

To provide a material for a tack coat capable of constructing a tack coat in which stickiness during construction is suppressed in one aspect, and in another aspect, a tack coat material capable of constructing a tack coat having high resistance to a load of water pressure is provided.SOLUTION: The above-mentioned problem is solved by providing a slurry-like tack coat material containing a fine aggregate and an asphalt emulsion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a material for a tack coat. More specifically, it relates to a slurry-like material for a tack coat and a method for constructing an asphalt pavement using the same.

Background Art

[0002] In paving work, as one of the main purposes of enhancing the adhesiveness with a newly laid asphalt mixture layer, asphalt materials such as cut-back asphalt, asphalt emulsion, and straight asphalt are sometimes sprayed on the surface of a construction surface such as a base layer or an asphalt stabilized treated roadbed. A coating containing such an asphalt material is called a tack coat.

[0003] As an asphalt material for a tack coat, an asphalt emulsion is generally used, and in particular, a cationic asphalt emulsion is often used. As a cationic asphalt emulsion used for a tack coat, an asphalt emulsion called PK-4 made from straight asphalt is known. Also known is a rubber-containing asphalt emulsion called PKR-T in which rubber is added to the asphalt emulsion to enhance the interlayer adhesion. When these asphalt emulsions are sprayed on a construction surface, the asphalt emulsion decomposes and moisture evaporates, forming an asphalt film on the surface of the construction surface. The asphalt film serves to improve the adhesiveness between the construction surface and the asphalt mixture layer laid thereon.

[0004] On the other hand, since the asphalt film is sticky, when a transport vehicle or construction machine passes over the construction surface sprayed with the asphalt emulsion, the asphalt film adheres to their wheels, and there is a problem that the asphalt film peels off. If the asphalt film peels off from the construction surface, there is a risk that the adhesiveness between the construction surface and the asphalt mixture layer laid thereon may be impaired. In addition, there is also a problem that the surrounding roads become dirty when the transport vehicle or construction machine travels around with the asphalt film adhering to the wheels.

[0005] In order to solve the problem of stickiness of the asphalt coating, for example, Patent Document 1 discloses a method of suppressing the adhesion of asphalt to the tires of construction machines and the soles of workers' shoes by incorporating a surface precipitant into an asphalt emulsion and precipitating the surface precipitant in powder form on the surface of the asphalt emulsion from which the moisture has evaporated. In order to precipitate the surface precipitant, it is necessary to ensure a curing time until the moisture in the asphalt emulsion has sufficiently evaporated. However, it is not always easy to ensure a sufficient curing time at the construction site. For example, in repair work, it is difficult to ensure a sufficient curing time during an overlay that must be carried out at night in winter.

[0006] Also, an asphalt emulsion called PKM-T, which suppresses the stickiness of the asphalt coating by adding resin to the asphalt emulsion, is known and is used as an asphalt emulsion for tack coat. According to PKM-T, although the adhesion of the asphalt coating is suppressed to a certain extent, stickiness still becomes apparent during the midsummer heat wave, and in particular, adhesion to the wheels of construction machines with high ground pressure such as asphalt finishers cannot be avoided. Although it is conceivable to suppress stickiness by further increasing the resin addition amount compared to PKM-T, in this case, there is a problem that the viscosity of the solution increases too much and it becomes difficult to emulsify.

[0007] On the other hand, after the construction of an asphalt pavement, if rainwater or the like infiltrates through cracks or construction joints on the road surface, the structural stability of the asphalt pavement may be impaired. That is, when water such as rainwater infiltrating through cracks or construction joints on the road surface passes through the surface layer and reaches, for example, the tack coat at the interface with the base layer, the penetration to the lower layer is hindered and it may stay there. In that state, for example, when a repeated load is applied vertically to the stagnant water by the weight load of a vehicle passing on the road surface, the pressurized water runs horizontally along the interface with the lower layer. As a result, the interlayer adhesion is broken and interlayer detachment may occur, or further, water penetrates into the lower layer, which may cause, for example, the weakening of the roadbed. Therefore, if a tack coat with high resistance to water pressure load can be obtained, it is considered extremely useful for extending the service life of asphalt pavements.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention has been made to solve the problems of the prior art as described above, and in one aspect, it is an object to provide a material for a tack coat that can construct a tack coat with suppressed stickiness during construction. Further, in another aspect, it is an object to provide a material for a tack coat that can construct a tack coat with high resistance to water pressure load.

Means for Solving the Problems

[0010] In the process of intensively conducting research efforts to solve the above problems, the inventors of the present invention have found that, according to a slurry-like tack coat material containing fine aggregate at a predetermined content, stickiness after the application of the tack coat is significantly suppressed, and further, the tack coat is excellent in adhesion between the application surface and the asphalt mixture layer laid thereon, thereby completing the present invention.

[0011] That is, in one aspect, the present invention solves the above problems by providing a slurry-like tack coat material containing fine aggregate and asphalt emulsion. As far as the inventors know, as a tack coat, it is almost exclusively limited to spraying asphalt emulsion, and a slurry-like tack coat material containing fine aggregate and asphalt emulsion is unprecedented.

Effects of the Invention

[0012] According to one aspect of the present invention, a tack coat material capable of constructing a tack coat with suppressed stickiness after application can be provided. Further, according to one aspect of the present invention, a tack coat material capable of constructing a tack coat excellent in interlayer adhesion and / or resistance to water pressure load can be provided.

Brief Description of the Drawings

[0013]

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Mode for Carrying Out the Invention

[0014] <Tack Coat Material> The tack coat material according to one aspect of the present invention is a slurry-like tack coat material containing fine aggregate and asphalt emulsion.

[0015] "Slurry" refers to a state in which solid particles and a liquid are mixed. The tack coat material according to one aspect of the present invention is in a slurry state and has appropriate fluidity, so it can be spread evenly on the construction surface.

[0016] An "asphalt emulsion" is a liquid composition in which asphalt is dispersed in water containing an emulsifier. Depending on the type of emulsifier contained in the asphalt emulsion, it is typically classified into anionic asphalt emulsions, cationic asphalt emulsions, and nonionic asphalt emulsions. The asphalt emulsion that can be used for the tack coat material according to one aspect of the present invention may be any of a cationic asphalt emulsion, anionic asphalt emulsion, and nonionic asphalt emulsion. However, from the viewpoint of adhesion to the construction surface, a cationic asphalt emulsion can be particularly preferably used. Further, the asphalt emulsion that can be used for the tack coat material according to one aspect of the present invention may be a modified asphalt emulsion containing appropriate modifying components such as the modifying components described later.

[0017] The "emulsifier" contained in the asphalt emulsion is not particularly limited in its type as long as it can disperse asphalt in water, and it may be any of an anionic emulsifier, a cationic emulsifier, an amphoteric emulsifier, or a nonionic emulsifier. Examples of anionic emulsifiers include sulfates of higher alcohols such as alkyl naphthalene sulfonates and alkyl diallyl ether sulfonates; succinates of higher alcohols such as dialkyl sulfosuccinates; phosphates of higher alcohols; and sulfates of higher alcohols such as alkyl allyl ether sulfates. Examples of cationic emulsifiers include alkylamine salts such as coconut amine acetate and stearylamine acetate; and quaternary ammonium salts such as lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, and alkyl benzyl dimethyl ammonium chloride. Examples of amphoteric emulsifiers include betaines such as acetic acid betaine, amide betaine, sulfo betaine, amide sulfo betaine, and imidazolium betaine. Examples of nonionic emulsifiers include polyoxyethylene alkyl phenyl ethers such as polyoxyethylene nonyl phenyl ether and polyoxyethylene octyl phenyl ether; polyoxyethylene alkyl ethers; sorbitan fatty acid esters; polyoxyethylene sorbitan fatty acid esters; and polyethylene glycol fatty acid esters. The emulsifier can be used by mixing one kind or two or more kinds thereof.

[0018] Moreover, there is no particular limitation on the type of asphalt contained in the asphalt emulsion used for the tack coat material according to one aspect of the present invention. Basically, any asphalt may be used. Examples of the asphalt that can be contained in the asphalt emulsion used for the tack coat material according to one aspect of the present invention include straight asphalt, blown asphalt, semi-blown asphalt, natural asphalt, solvent-deasphalted asphalt, and the like. Further, it may be a modified asphalt in which appropriate modifying components such as thermoplastic resins and rubbers are mixed with these asphalts. That is, in a certain preferred embodiment, the tack coat material according to one aspect of the present invention can be a slurry-type tack coat material containing fine aggregate, an asphalt emulsion, and further a modifying component, and can also be a slurry-type tack coat material containing fine aggregate and a modified asphalt emulsion. Note that the modified asphalt emulsion may be a premix-type modified asphalt emulsion obtained by emulsifying a mixture of a modifying component and asphalt, or a postmix-type modified asphalt emulsion obtained by mixing a modifying component into an asphalt emulsion. According to the tack coat material containing a modifying component such as a thermoplastic resin and / or rubber, a tack coat with higher adhesiveness between the construction surface and the asphalt mixture layer laid thereon and further suppressed stickiness can be obtained.

[0019] There is no particular limitation on the type of the modifying component. For example, styrenic resins such as styrene-butadiene block copolymer (SBS), styrene-isoprene block copolymer (SIS), and styrene-butadiene random copolymer (SBR); ethylene-based resins such as ethylene-acrylic acid copolymer (EAA), ethylene-vinyl acetate copolymer (EVA), and ethylene-ethyl acrylate copolymer (EEA); polystyrene-polyethylene butylene block copolymer (SEBS); polyester-based resins, nylon-based resins, acrylic-based resins; natural rubber, chloroprene rubber, isoprene rubber, styrene-butadiene rubber, styrene-isoprene rubber, butadiene rubber, butyl rubber, halogenated butyl rubber, chlorinated polyethylene, chlorosulfonated polyethylene, ethylene-propylene rubber, EPT rubber, alfin rubber, styrene-butadiene block polymerized rubber, styrene-isoprene block polymerized rubber, etc.; petroleum resins such as C5-based petroleum resin, C9-based petroleum resin, C5 / C9-based petroleum resin, and cyclopentadiene-based petroleum resin; terpene resins such as polyterpene resin obtained by polymerizing terpene monomers and terpene-phenol resin obtained by polymerizing terpene monomers and phenols; oils such as aromatic hydrocarbons and aliphatic hydrocarbons. The modifying component may be one type or a mixture of two or more types of modifying components.

[0020] There is no particular limitation on the content of the modifying component such as thermoplastic resin and / or rubber that can be contained in the asphalt emulsion. For example, it can be 1 to 90% by mass, 5 to 80% by mass, 10 to 70% by mass, 20 to 60% by mass, or 30 to 50% by mass per evaporation residue of the asphalt emulsion. The content of the modifying component in the asphalt emulsion can be appropriately set according to the required properties of the tack coat. In the present specification, when a numerical range is indicated using "~", unless otherwise specified, it means a numerical range including the upper limit value and the lower limit value.

[0021] On the other hand, "fine aggregate" refers to sand, gravel, crushed sand, crushed stone, and other similar granular materials, that is, among the aggregates, those with a fine particle size, typically those with a maximum particle size of 2.5 mm or less.

[0022] As the fine aggregate that can be used for the tack coat material according to one aspect of the present invention, although it depends on the thickness of the tack coat to be constructed, those having a maximum particle size of 0.1 mm or more and 2.0 mm or less are preferable, those having a maximum particle size of 0.6 mm or more and 1.8 mm or less are more preferable, those having a maximum particle size of 0.6 mm or more and 1.5 mm or less are even more preferable, and those having a maximum particle size of 0.8 mm or more and 1.4 mm or less are even more preferably.

[0023] In a certain preferred embodiment, the fine aggregate that can be used for the tack coat material according to one aspect of the present invention is preferably a fine aggregate having a continuous particle size, and more preferably a fine aggregate having a continuous particle size represented by Fuller's maximum density curve. When the tack coat material according to one aspect of the present invention contains a fine aggregate having such a particle size as the fine aggregate, the filling degree of the obtained tack coat is increased, and a tack coat showing excellent water permeability resistance can be obtained. Further, the fine aggregate having the above particle size enables the interface between the upper and lower asphalt layers having minute irregularities and the tack coat layer to mesh more firmly, and is considered to contribute to the excellent interlayer adhesiveness of the tack coat material according to one aspect of the present invention.

[0024] On the other hand, regarding the ratio of the fine aggregate and the asphalt emulsion contained in the tack coat material according to one aspect of the present invention, in a certain preferred embodiment, when the content of the fine aggregate is 100 parts by mass, the content of the evaporation residue of the asphalt emulsion is preferably 19 parts by mass or less, more preferably less than 19 parts by mass, even more preferably 18 parts by mass or less, and even more preferably 17 parts by mass or less. As shown in the experimental examples described later, when the content of the evaporation residue of the asphalt emulsion is less than 19 parts by mass with respect to 100 parts by mass of the fine aggregate, the stickiness of the tack coat after spreading the tack coat material can be significantly suppressed.

[0025] Note that the "evaporation residue" means the amount of solid content remaining after evaporating the moisture in the asphalt emulsion. According to the Japanese Industrial Standard (JIS K2208 Asphalt Emulsion) for petroleum asphalt emulsion, the evaporation residue content of the asphalt emulsion is specified to be 50 to 60 mass% or more, depending on the type of asphalt emulsion.

[0026] On the other hand, in a certain preferred embodiment, when the content of the fine aggregate in the tack coat material according to one aspect of the present invention is 100 parts by mass, the content of the evaporation residue of the asphalt emulsion is preferably 15 parts by mass or more, and more preferably 16 parts by mass or more. As shown in the experimental examples described later, when the content of the evaporation residue of the asphalt emulsion is 15 parts by mass or more when the fine aggregate is 100 parts by mass, a tack coat showing excellent interlayer adhesion can be obtained. Further, when the content of the evaporation residue of the asphalt emulsion is 16 parts by mass or more when the fine aggregate is 100 parts by mass, a tack coat having excellent interlayer adhesiveness and / or water permeability resistance can be obtained.

[0027] As described above, according to the tack coat material according to one aspect of the present invention, a tack coat excellent in tack resistance, interlayer adhesiveness, and / or water permeability resistance of the tack coat can be obtained. Judging comprehensively from the viewpoints of the tack resistance, interlayer adhesiveness, and water permeability resistance of the obtained tack coat, in a certain preferred embodiment, when the content of the fine aggregate in the tack coat material according to one aspect of the present invention is 100 parts by mass, the content of the evaporation residue of the asphalt emulsion is preferably 15 parts by mass or more and 19 parts by mass or less, more preferably 15 parts by mass or more and less than 19 parts by mass, still more preferably 15 parts by mass or more and 18 parts by mass or less, even more preferably 15 parts by mass or more and 17 parts by mass or less, and particularly preferably 16 parts by mass or more and 17 parts by mass or less.

[0028] There is no particular limitation on the aggregate content in the tack coat material according to one aspect of the present invention. For example, it can be 60% by mass or more and 80% by mass or less, more preferably 62% by mass or more and 78% by mass or less, still more preferably 65% by mass or more and 75% by mass or less, and even more preferably 67% by mass or more and 73% by mass or less. On the other hand, there is no particular limitation on the asphalt emulsion content in the tack coat material according to one aspect of the present invention. For example, it can be 10% by mass or more and 30% by mass or less, more preferably 12% by mass or more and 28% by mass or less, still more preferably 14% by mass or more and 26% by mass or less, and even more preferably 15% by mass or more and 25% by mass or less. On the other hand, the water content in the tack coat material according to one aspect of the present invention can be, for example, 5% by mass or more and 30% by mass or less, preferably 10% by mass or more and 25% by mass or less, more preferably 15% by mass or more and 25% by mass or less.

[0029] Also, in a certain preferred embodiment, the tack coat material according to one aspect of the present invention may further contain other additive components. The other additive components can be, for example, the above-described modifying components, alkaline additives, water, etc. There is no particular limitation on the alkaline additive as long as it is an additive showing alkalinity. For example, as shown in the experimental examples described later, cement can be used. There is no particular limitation on the content of the alkaline additive. For example, it can be 0.1% by mass or more and 5% by mass or less, 0.5% by mass or more and 4.5% by mass or less, 1% by mass or more and 4% by mass or less, 1.5% by mass or more and 3.5% by mass or less, 2% by mass or more and 3% by mass or less. The alkaline additive may be added immediately before the tack coat material is used, or may be sprayed on the construction surface immediately after the tack coat material is spread evenly on the construction surface. For example, when a cationic asphalt emulsion is used as the asphalt emulsion, since the alkaline additive promotes the decomposition of the asphalt emulsion, it is preferably added immediately before the tack coat material is used or sprayed on the construction surface immediately after the tack coat material is spread evenly on the construction surface.

[0030] As described above, since the material for tack coat according to one aspect of the present invention is in a slurry state and has appropriate fluidity, it can be easily spread evenly on the construction surface. Here, the appropriate fluidity means, for example, in terms of the pot life at 20°C, it can be 15 minutes or more, 20 minutes or more, 25 minutes or more, or 30 minutes or more, and in terms of the pot life at 10°C, it can be 15 minutes or more, 20 minutes or more, 25 minutes or more, or 30 minutes or more. The pot life means the time until the fluidity is lost when a predetermined amount of the material for tack coat is put into a container of a predetermined volume, stirred with a rod or the like, and then allowed to stand. The pot life can be measured by a person skilled in the art by an appropriate method. For example, as shown in the experimental examples described later, 300 g of the material for tack coat is put into a container having a substantially cylindrical shape (upper diameter: φ122 mm, lower diameter: φ103 mm, height: 146 mm), stirred with a rod, and then the time until the fluidity is lost when allowed to stand is measured.

[0031] Further, in a certain preferred embodiment, the curing time of the material for tack coat according to one aspect of the present invention can be, for example, 15 minutes to 45 minutes, preferably 20 minutes to 40 minutes, more preferably 25 minutes to 35 minutes at 20°C, and can be, for example, 20 minutes to 80 minutes, preferably 30 minutes to 70 minutes, more preferably 40 minutes to 60 minutes at 10°C. The curing time means the time required until the material for tack coat no longer adheres to the finger when the material for tack coat is spread on a plate to a predetermined thickness and touched with a finger. The curing time can be measured by a person skilled in the art by an appropriate method.

[0032] When constructing a tack coat using the material for tack coat according to one aspect of the present invention, typically, the material for tack coat may be spread evenly on the construction surface. There is no particular limitation on the method of spreading the material for tack coat on the construction surface. For example, it may be spread evenly manually using a rubber rake or the like, or may be spread evenly by a construction machine equipped with a spreader box.

[0033] Further, the material for tack coat according to one aspect of the present invention may be prepared in advance at a factory or the like, transported to the construction site, and spread evenly, or may be prepared as needed at the construction site and spread evenly. However, it is preferable to prepare and spread it as needed at the construction site. The material for tack coat can be prepared by mixing fine aggregate, asphalt emulsion, alkaline additive, water, and / or appropriate additives. For mixing these materials, for example, a construction machine equipped with a fine aggregate hopper, an asphalt emulsion tank, a cement hopper, a water hopper, and / or an additive component tank and a mixer for mixing each component may be used. The construction machine may further be provided with a spreader box. According to such a construction machine, it is very convenient because the material for tack coat according to one aspect of the present invention can be prepared as needed and spread evenly at the same time.

[0034] There is no particular limitation on the thickness at which the material for tack coat according to one aspect of the present invention is applied. Basically, it may be a thickness equal to or greater than the maximum particle size of the fine aggregate contained in the material for tack coat. For example, it may be 0.5 mm or more and 4 mm or less. From the viewpoints of resistance to water pressure load and cost, etc., it is preferably 1.0 mm or more and 3.0 mm or less, and more preferably 1.5 mm or more and 2.5 mm or less. In this case, as the fine aggregate, fine aggregate having a maximum particle size of 0.6 mm or more and 1.8 mm or less, more preferably 0.8 mm or more and 1.6 mm or less, and even more preferably 1.0 mm or more and 1.4 mm or less can be preferably used. Here, the "thickness" means the finished thickness of the tack coat.

[0035] There is no particular limitation on the type of the construction surface on which the tack coat is constructed using the material for tack coat according to one aspect of the present invention, that is, the construction surface on which the material for tack coat according to one aspect of the present invention is spread evenly. The construction surface may be, for example, an asphalt mixture surface (asphalt concrete surface), a concrete surface, or an asphalt stabilized roadbed. By constructing a tack coat on these construction surfaces, the adhesiveness with the asphalt mixture layer laid thereon can be enhanced, and thus the stability of the constructed pavement can be enhanced.

[0036] After spreading the material for tack coat according to one aspect of the present invention, if necessary, the laid material for tack coat may be compacted. The compaction of the material for tack coat may be performed using a tamper or the like, or may be performed by rolling with a tire roller or the like. The compaction of the material for tack coat may be performed immediately after compacting the material for tack coat for tack coat use, or may be performed after curing for a predetermined time. According to the material for tack coat according to one aspect of the present invention, since the stickiness of the tack coat after construction is reduced, even if compaction is performed immediately after construction, the advantage that the adhesion of the tack coat to the wheels of the construction machine is reduced can be obtained.

[0037] <Method for constructing asphalt pavement> According to another aspect of the present invention, there is provided a method for constructing an asphalt pavement including a step of spreading a slurry-like mixture containing fine aggregate and asphalt emulsion on a construction surface, and a step of laying an asphalt mixture on the construction surface on which the mixture has been spread evenly.

[0038] <Step of spreading a slurry-like mixture containing fine aggregate and asphalt emulsion on a construction surface> Literally, it is a step of spreading a slurry-like mixture containing fine aggregate and asphalt emulsion on a construction surface. In other words, it is a step of constructing a tack coat made of the mixture on the construction surface. The slurry-like mixture containing fine aggregate and asphalt emulsion and the method of spreading it evenly have already been described in the column for the description of the material for tack coat, so the description will be omitted for the sake of brevity.

[0039] As described above, in a certain preferred embodiment, it is preferable that the above mixture spread on the construction surface is prepared as needed at the construction site. That is, in a certain preferred embodiment, the method for constructing an asphalt pavement according to one aspect of the present invention may further include a step of mixing fine aggregate and asphalt emulsion before the step of spreading the slurry-like material for tack coat on the construction surface to prepare a slurry-like mixture (slurry-like material for tack coat).

[0040] In the step of preparing the slurry-like mixture, if necessary, appropriate modifying components in the form of a polymer emulsion or the like, water, and other additive components such as an alkaline additive may be further mixed. At this time, there is no particular limitation on the order of mixing the fine aggregate, the asphalt emulsion, and the other additive components. However, when mixing an alkaline additive as the other additive component, it is preferable that the alkaline additive is added last or all the materials are mixed simultaneously. This is because when the alkaline additive is mixed, the decomposition of the asphalt emulsion may be promoted.

[0041] <Step of paving the asphalt mixture on the construction surface> This is a step of paving the asphalt mixture on a construction surface where a slurry-like mixture containing a fine aggregate and an asphalt emulsion has been spread evenly, that is, a construction surface on which a tack coat has been constructed.

[0042] The "asphalt mixture" refers to a paving material obtained by mixing aggregate, asphalt, filler, etc. at a predetermined mixing ratio. There is no particular limitation on the type of asphalt mixture to be paved on the construction surface, and basically any asphalt mixture may be used. For example, it may be a hot asphalt mixture or a cold asphalt mixture, but from the viewpoint of adhesion to the constructed tack coat, a hot asphalt mixture is preferable.

[0043] When paving an asphalt mixture, typically, after constructing a tack coat on the construction surface in the above process, the asphalt mixture is spread evenly on the construction surface where the tack coat has been constructed, using manual labor or construction machinery such as an asphalt finisher. The asphalt mixture spread on the construction surface is compacted using an appropriate compaction device such as a plate compactor, a tamper, or a rolling compactor such as a tire roller or a road roller, and is paved as an asphalt mixture layer. There is no particular limitation on the thickness of the asphalt mixture layer to be paved, and an asphalt mixture layer with an appropriate thickness corresponding to the normal paving thickness can be paved. Generally, the thickness of one layer of the asphalt mixture layer constituting the asphalt pavement is 3 to 7 cm, and in the case of thin layer paving, it is about 2 to 3 cm, more generally about 2.5 cm.

[0044] Hereinafter, the present invention will be described in more detail based on experimental examples. Note that these experimental examples do not limit the scope of the present invention in any way.

[0045] <Experiment 1: Evaluation of Pot Life and Curing Time> A slurry-like tack coat material containing fine aggregate and asphalt emulsion was prepared, and its pot life and curing time were evaluated.

[0046] Specifically, 69.8 parts by mass of fine aggregate (maximum particle size 1.2 mm), 22.3 parts by mass of cationic modified asphalt emulsion (evaporation residue 50%), 5.6 parts by mass of water, and 2.3 parts by mass of cement were mixed to prepare a slurry-like tack coat material as Test Specimen 1-1. As the fine aggregate, fine aggregate prepared to have a continuous particle size represented by Fuller's maximum density curve was used. 300 g of the obtained Test Specimen 1-1 was placed in a container having a substantially cylindrical shape with an upper diameter of φ122 mm × a lower diameter of φ103 mm × a height of 146 mm, and was sufficiently stirred with a rod until it flowed. After stopping the stirring, it was allowed to stand, and the time until the fluidity was lost (pot life) was measured. The pot life at 20°C was 23 minutes, and the pot life at 10°C was 30 minutes. It was determined that it had a sufficient pot life at any temperature.

[0047] On one hand, after spreading the test sample 1-1 on a plate to a thickness of 2 mm, it was touched with a finger every predetermined time, and the time (curing time) until the slurry-like tack coat material did not adhere to the finger and only clear water came out was measured. The curing time at 20 °C was 32 minutes, and the pot life at 10 °C was 50 minutes. It was judged that suitable curing times were shown at any temperature.

[0048] <Experiment 2: Evaluation of Tackiness of Tack Coat> A tack coat composed of a slurry-like tack coat material containing fine aggregate and asphalt emulsion was constructed on the surface of the asphalt mixture layer, and the tackiness of the constructed tack coat was evaluated.

[0049] Specifically, a test sample 2-1 containing 69.8% by mass of fine aggregate (maximum particle size 1.2 mm), 22.3% by mass of cationic modified asphalt emulsion (evaporation residue 50%), 5.6% by mass of water, and 2.3% by mass of cement, or a test sample 2-2 containing 69.8% by mass of fine aggregate (maximum particle size 600 μm), 22.3% by mass of cationic modified asphalt emulsion (evaporation residue 50%), 5.6% by mass of water, and 2.3% by mass of cement was spread evenly on a base specimen made of a dense-graded asphalt mixture (13) to a thickness of 2 mm and cured for 12 hours to construct a tack coat, and specimens 2-1 and 2-2 were obtained. As the fine aggregate, fine aggregate prepared to have a continuous particle size represented by Fuller's maximum density curve was used. Also, as a comparison object, a commercially available tire adhesion-inhibiting type asphalt emulsion, PKM-T (product name: Farmzol, manufactured by Nichireki Co., Ltd.), was sprayed on a base specimen made of a dense-graded asphalt mixture (13) at a spraying amount of 0.4 kg / m 2 (theoretical thickness 0.2 mm) and cured for 12 hours to construct a tack coat, and specimen 2-3 was obtained.

[0050] The obtained specimen was placed on a wheel tracking tester (manufacturer: Nakajima Giken Co., Ltd., model number: NA-556), and a wheel load of 1470 N equivalent to the asphalt finisher load was applied for 10 minutes at a test temperature of 60 °C simulating the road surface temperature in midsummer. After the application of the wheel load, the area ratio (%) of the asphalt coating adhered to the test wheel (hereinafter sometimes referred to as "the adhesion rate of the asphalt coating to the test wheel") was visually evaluated. The obtained test results are shown in Figure 1.

[0051] As shown in Figure 1, when a load of 1470 N equivalent to the asphalt finisher was applied to Specimen 2-3 having a tack coat formed using PKM-T, a commercially available tire adhesion suppressing asphalt emulsion, at a test temperature of 60 °C assuming the road surface temperature in midsummer, the adhesion rate of the asphalt coating to the test wheel was 97%, and the result was that the asphalt coating adhered to almost the entire surface of the test wheel. This result shows that even when a tack coat is constructed using PKM-T, a commercially available asphalt emulsion for a tire adhesion suppressing tack coat, at a test temperature of 60 °C assuming the road surface temperature in midsummer, when a load of 1470 N equivalent to the asphalt finisher is applied, the asphalt coating adheres significantly to the test wheel.

[0052] In contrast, Specimen 2-1 with a tack coat formed by spreading a test sample 2-1, which is a slurry-type tack coat material containing fine aggregate with a maximum particle size of 1.2 mm (in Fig. 1, "1.2 mm top") and asphalt emulsion, and Specimen 2-2 with a tack coat formed by spreading a test sample 2-2, which is a tack coat material containing fine aggregate with a maximum particle size of 600 μm (in Fig. 1, "600 μm top") and asphalt emulsion, even when a load of 1470 N, which is equivalent to the load of an asphalt finisher, was applied at a test temperature of 60°C, the adhesion rates of the asphalt film to the test wheel were 4% and 2% respectively, and almost no adhesion of the asphalt film to the test wheel was observed in any of the specimens. This result indicates that, according to the tack coat material using a slurry-type mixture containing fine aggregate and asphalt emulsion, a tack coat with significantly suppressed stickiness can be obtained even at high temperatures like midsummer, and its stickiness resistance far exceeds that of a tack coat obtained from a commercially available tire adhesion suppression type asphalt emulsion.

[0053] <Experiment 3: Evaluation of the Stickiness of the Tack Coat> A tack coat was constructed on the surface of the asphalt mixture layer using slurry-type tack coat materials with different ratios of the contents of fine aggregate and asphalt emulsion, and the stickiness resistance of the constructed tack coat was evaluated.

[0054] Specifically, fine aggregate (maximum particle size 1.2 mm), cationic modified asphalt emulsion (evaporation residue 50%), water, and cement were mixed at the mixing ratios shown in Table 1 below, and test samples 3-1 to 3-4 with different ratios of fine aggregate to asphalt emulsion were prepared. This was evenly spread to a thickness of 2 mm on a base test specimen made of a dense-graded asphalt mixture (13) and cured for 12 hours to obtain test specimens 3-1 to 3-4. As the fine aggregate, fine aggregate prepared to have a continuous particle size represented by Fuller's maximum density curve was used. The obtained test specimens were installed in a wheel tracking tester, and a wheel load of 1470 N equivalent to the asphalt finisher load was applied for 10 minutes at a test temperature of 60°C simulating the road surface temperature in midsummer. After the application of the wheel load, the area ratio (%) of the asphalt film adhering to the test wheel (hereinafter sometimes referred to as the "adhesion rate of the asphalt film to the test wheel") was visually evaluated. The obtained test results are shown in Figure 2.

[0055]

Table 1

[0056] As shown in Fig. 2, specimens 3-2 to 3-4 with tack coats constructed by spreading test specimens 3-2 containing fine aggregate and asphalt emulsion at a ratio of 100:34, test specimens 3-3 containing fine aggregate and asphalt emulsion at a ratio of 100:32, and test specimens 3-4 containing fine aggregate and asphalt emulsion at a ratio of 100:30, even when a load of 1470 N, which is equivalent to the load of an asphalt finisher, was applied at a test temperature of 60 °C simulating the road surface temperature in midsummer, the adhesion rates of the asphalt film to the test wheel were only 2%, 4%, and 0% respectively, indicating that the adhesion of the asphalt film to the test wheel was significantly suppressed. In contrast, in specimen 3-1 with a tack coat constructed by spreading test specimen 3-1 containing a slightly larger amount of asphalt emulsion, i.e., fine aggregate and asphalt emulsion at a ratio of 100:38, under the same test conditions, the adhesion rate of the asphalt film to the test wheel reached 97%, and asphalt film adhesion was observed on almost the entire surface of the test wheel. This result shows that in the material for the tack coat containing fine aggregate and asphalt emulsion, as the content of the asphalt emulsion relative to the fine aggregate increases, the stickiness of the tack coat is not sufficiently suppressed, and the tack coat easily adheres to the test wheel.

[0057] From the above results, from the viewpoint of suppressing the stickiness of the tack coat, in the slurry-like material for the tack coat according to one aspect of the present invention, the content of the asphalt emulsion relative to 100 parts by mass of the fine aggregate is preferably less than 38 parts by mass, more preferably 37 parts by mass or less, and even more preferably 36 parts by mass or less. In other words, based on the content of the evaporation residue in the asphalt emulsion, from the viewpoint of suppressing the stickiness of the tack coat, the content of the evaporation residue of the asphalt emulsion is preferably less than 19 parts by mass, more preferably 18.5 parts by mass or less, and even more preferably 18 parts by mass or less with respect to 100 parts by mass of the fine aggregate. In any case, it was shown that with the slurry-like material for the tack coat containing fine aggregate and asphalt emulsion, a tack coat with suppressed stickiness can be obtained even at high temperatures such as in midsummer over a wide range of mixing ratios of the fine aggregate and the asphalt emulsion.

[0058] <Experiment 4: Evaluation of Tensile Adhesion Strength> Next, in order to evaluate the adhesiveness of a tack coat constructed from a slurry - type tack coat material containing fine aggregate and asphalt emulsion, the tensile adhesion strength was evaluated.

[0059] The tensile adhesion strength was evaluated by the following test method. First, on a base specimen with a thickness of 50 mm made of a dense - graded asphalt mixture (13) containing modified asphalt for heavy loads, a test sample 4 - 1 containing 69.8 mass% of fine aggregate with a maximum particle size of 1.2 mm, 22.3 mass% of cationic modified asphalt emulsion (evaporation residue 50%), 5.6 mass% of water, and 2.3 mass% of cement, or a test sample 4 - 2 containing 69.8 mass% of fine aggregate with a maximum particle size of 0.6 mm, 22.3 mass% of cationic modified asphalt emulsion (evaporation residue 50%), 5.6 mass% of water, and 2.3 mass% of cement was spread evenly with a thickness of 2 mm and cured for 12 hours to construct a tack coat. Then, on the base specimen with the tack coat constructed, an upper - layer specimen with a thickness of 50 mm made of an asphalt mixture with the same composition as the base specimen was paved. After 12 hours, it was cut into a prismatic shape with a width of 50 mm × a depth of 50 mm, and the upper and lower surfaces were cut by 10 mm each to obtain test specimens 4 - 1 and 4 - 2 for the tensile test. Note that as the fine aggregate, fine aggregate prepared to have a continuous particle size represented by Fuller's maximum density curve was used. An overview of the test specimen preparation method is shown in Fig. 3A.

[0060] On the other hand, as a comparison object, instead of spreading the test sample 4 - 1 or the test sample 4 - 2 evenly to construct a tack coat, a commercially available tire - adhesion - suppressing asphalt emulsion, PKM - T (trade name: Farmzol, manufactured by Nichireki Co., Ltd.), was sprayed at a spraying rate of 0.4 kg / m 2 and cured for 12 hours to construct a tack coat. In the same manner as the above procedure, a test specimen 4 - 3 for the tensile test was obtained.

[0061] The tensile adhesion strength of the specimens obtained by the above procedure was measured using a universal material testing machine (manufacturer: Instron, model number: 5900 series). The tensile speed was 1 mm / min, and the test temperatures were -10°C, 23°C, and 50°C. Independent tests were conducted three times for each specimen and each test temperature. The average value of the obtained tensile adhesion strength is shown in Figure 3B. In Figure 3B, the upper and lower ends of the error bars represent the maximum value and the minimum value, respectively.

[0062] As shown in Figure 3B, at all test temperatures from -10°C to 50°C, Specimens 4-1 and 4-2 with tack coats constructed from Test Specimens 4-1 and 4-2, which are slurry-type tack coat materials containing fine aggregate and asphalt emulsion, exhibited tensile adhesion strength equal to or higher than that of Specimen 4-3 with a tack coat constructed from PKM-T. This result indicates that according to the slurry-type tack coat material containing fine aggregate and asphalt emulsion, not only is stickiness suppressed, but a tack coat with sufficient interlayer adhesion strength can be constructed. There was no clear difference between the tensile adhesion strength of Specimen 4-1 with a tack coat constructed from Test Specimen 4-1 where the maximum particle size of the fine aggregate is 1.2 mm and the tensile adhesion strength of Specimen 4-2 with a tack coat constructed from Test Specimen 4-2 where the maximum particle size of the fine aggregate is 0.6 mm.

[0063] <Experiment 5: Evaluation of Shear Adhesion Strength> The shear adhesion strength of the tack coat constructed from the slurry-type tack coat material containing fine aggregate and asphalt emulsion was evaluated.

[0064] Specifically, on a base specimen with a thickness of 75 mm made of a dense-graded asphalt mixture (13) containing modified asphalt for heavy loads, a test sample 5-1 containing 69.8% by mass of fine aggregate (maximum particle size 1.2 mm), 22.3% by mass of cationic modified asphalt emulsion (evaporation residue 50%), 5.6% by mass of water, and 2.3% by mass of cement was spread evenly at a thickness of 2 mm and cured for 12 hours to construct a tack coat. Then, on the base specimen on which the tack coat was constructed, a top specimen with a thickness of 75 mm made of the same asphalt mixture as the base specimen was laid. After 12 hours, the specimen was cut into a predetermined shape to obtain a specimen 5-1 for the shear test. Note that, as the fine aggregate, fine aggregate prepared to have a continuous particle size represented by Fuller's maximum density curve was used, and the dimensions of the adhesive surface between the top specimen and the base specimen per specimen were 70 mm in width in the shear direction × 50 mm in width in the depth direction. An overview of the method for preparing the specimen is shown in Fig. 4A.

[0065] On the other hand, as a comparison target, instead of spreading the test sample 5-1 evenly to construct a tack coat, PKM-T (product name: Farmzol, manufactured by Nichirei Corporation), a commercially available asphalt emulsion with tire adhesion suppression properties, was sprayed at a spraying rate of 0.4 kg / m 2 (theoretical thickness 0.2 mm), and a specimen 5-2 for the shear test was obtained in the same procedure as above except that it was cured for 12 hours to construct a tack coat.

[0066] The shear adhesion strength of the specimens obtained by the above procedure was evaluated using a universal material testing machine (manufacturer: Instron, model number: 5900 series). The shear rate was 1 mm / min, and the test temperatures were -10°C, 23°C, and 50°C. Independent tests were conducted 3 times for each specimen and each test temperature. The average value of the obtained shear adhesion strength is shown in Fig. 4B. In Fig. 4B, the upper and lower ends of the error bars represent the maximum value and the minimum value, respectively.

[0067] As shown in Fig. 4B, at all test temperatures from -10°C to 50°C, the specimen 5-1 with a tack coat constructed from the test sample 5-1, which is a slurry-like tack coat material containing fine aggregate and asphalt emulsion, showed a shear adhesion strength higher than that of the specimen 5-2 with a tack coat constructed from PKM-T. This result indicates that according to the slurry-like tack coat material containing fine aggregate and asphalt emulsion, not only stickiness is suppressed, but also a tack coat with excellent interlayer adhesion strength can be constructed.

[0068] <Experiment 6: Evaluation of Tensile Adhesion Strength> The tensile adhesion strength of tack coats constructed using slurry-like tack coat materials with different ratios of fine aggregate and asphalt emulsion contents was evaluated.

[0069] The tensile adhesion strength was evaluated by the following test method. First, fine aggregate (maximum particle size 1.2 mm), cationic modified asphalt emulsion (evaporation residue 50%), water, and cement were mixed at the mixing ratios shown in Table 2 below to prepare test samples 6-1 to 6-3 with different ratios of fine aggregate and asphalt emulsion. Except for using test samples 6-1 to 6-3 instead of test samples 4-1 and 4-2, in the same procedure as described in Experiment 4, specimens 6-1 to 6-3 for tensile test were obtained. Note that as the fine aggregate, fine aggregate prepared to have a continuous particle size represented by Fuller's maximum density curve was used. Also, instead of spreading test samples 6-1 to 6-3 evenly to construct a tack coat, PKM-T (trade name: Farmzol, manufactured by Nichireki Co., Ltd.), a commercially available tire adhesion suppression type asphalt emulsion, was sprayed at a spraying amount of 0.4 kg / m 2 (theoretical thickness 0.2 mm), and a specimen 6-4 was obtained in the same procedure as above except that a tack coat was constructed by curing for 12 hours. A tensile test was conducted under the same conditions as described in Experiment 4 to evaluate the tensile adhesion strength. The obtained results are shown in Fig. 5.

[0070]

Table 2

[0071] As shown in Fig. 5, test specimens 6-1 to 6-3 having a tack coat constructed by spreading slurry-like tack coat materials containing fine aggregate and asphalt emulsion in a ratio of 100:34 to 100:30 showed tensile adhesion strength equal to or higher than that of specimen 6-4 having a tack coat constructed from PKM-T at any test temperature. This result indicates that according to the slurry-like tack coat material containing fine aggregate and asphalt emulsion, not only is stickiness suppressed over a wide range of mixing ratios of fine aggregate and asphalt emulsion, but a tack coat having sufficient interlayer adhesion strength can be constructed.

[0072] <Experiment 7: Pressurized water permeability test> The pressurized water permeability of specimens having a tack coat constructed from a slurry-like tack coat material containing fine aggregate and asphalt emulsion was evaluated.

[0073] Specifically, on a base specimen (base layer, compaction degree 96%) made of an asphalt mixture (FB13) for a bridge leveling layer, a test sample 7-1 containing 69.8% by mass of fine aggregate (maximum particle size 1.2 mm), 22.3% by mass of a cationic modified asphalt emulsion (evaporation residue 50%), 5.6% by mass of water, and 2.3% by mass of cement, or a test sample 7-2 containing 69.8% by mass of fine aggregate (maximum particle size 0.6 mm), 22.3% by mass of a cationic modified asphalt emulsion (evaporation residue 50%), 5.6% by mass of water, and 2.3% by mass of cement was spread evenly to a predetermined thickness (0 mm, 2 mm, 3 mm, 4 mm) and cured for 12 hours to construct a tack coat. On the base specimen with the tack coat constructed, a top specimen (surface layer, compaction degree 100%) made of an asphalt mixture (13) for high-performance pavement type I used for drainage pavement was laid and cured for 12 hours to obtain a specimen for the pressurized water permeability test.

[0074] The pressure permeation test was conducted using a triple pressure permeation tester (manufacturer: Nikken Co., Ltd.) under the conditions of a permeation pressure of 0.15 MPa, a lateral pressure of 0.20 MPa, a pressurization time of 24 hours, a measurement time of 10 minutes, and a test temperature of room temperature. The obtained results are shown in Figure 6.

[0075] As shown in Figure 6, by constructing a tack coat made of a slurry-like tack coat material containing fine aggregate and asphalt emulsion, a decrease in the permeability coefficient was observed. In particular, for the specimen having a tack coat constructed from the test sample 7-1 with a maximum particle size of the fine aggregate of 1.2 mm, when the finished thickness of the tack coat exceeded 2 mm, the permeability coefficient became 1.0×10 -8 (cm / s) or less, showing a high water shielding property of being substantially water-impermeable. On the other hand, for the specimen having a tack coat constructed from the test sample 7-2 with a maximum particle size of the fine aggregate of 0.6 mm, although the permeability coefficient gradually decreased as the finished thickness increased, it did not stably reach 1.0×10 -8 (cm / s) or less even when the finished thickness reached 4 mm. The above results indicate that according to the slurry-like tack coat material containing fine aggregate and asphalt emulsion, an asphalt pavement showing water resistance can basically be obtained regardless of the particle size of the fine aggregate. From the viewpoint of enhancing the water resistance of the asphalt pavement, the maximum particle size of the fine aggregate can be 0.6 mm or more, preferably 0.6 mm or more and 1.8 mm or less, more preferably 0.8 mm or more and 1.6 mm or less, still more preferably 0.9 mm or more and 1.4 mm or less, and even more preferably 1.0 mm or more and 1.3 mm or less, and particularly preferably 1.2 mm. On the other hand, the finished thickness of the tack coat material can be, for example, 1.5 mm or more and 4.0 mm or less, preferably 2.0 mm or more and 4.0 mm or less.

[0076] <Experiment 8: Pressure Permeation Test> Tack coats were constructed using slurry-like tack coat materials with different ratios of the contents of fine aggregate and asphalt emulsion, and the pressure permeability of the specimens having the constructed tack coats was evaluated.

[0077] Specifically, fine aggregate (maximum particle size 1.2 mm), cationic modified asphalt emulsion (evaporation residue 50%), water, and cement were mixed at the mixing ratios shown in Table 3 below. Test samples 8-1 to 8-4 with different ratios of fine aggregate to asphalt emulsion were prepared. Except for using test samples 8-1 to 8-4 instead of test samples 7-1 and 7-2, specimens for the pressure permeability test were obtained and the permeability coefficient was evaluated in the same manner as the procedure described in Experiment 7. The results obtained are shown in Figure 7.

[0078]

Table 3

[0079] As shown in Figure 7, specimens with tack coats constructed by spreading test samples 8-1 to 8-3, which are slurry-type tack coat materials containing fine aggregate and asphalt emulsion in a ratio of 100:38 to 100:32, had a permeability coefficient of 1.0×10 -8 (cm / s) or less and were substantially impermeable when the finished thickness of the tack coat was 2 mm. In contrast, a specimen with a tack coat constructed by spreading test sample 8-4, which is a slurry-type tack coat material containing fine aggregate and asphalt emulsion in a ratio of 100:30, that is, the asphalt emulsion content is slightly lower compared to test samples 8-1 to 8-3, had a permeability coefficient of 1.0×10 -8(cm / s) or less, and it became substantially water-impermeable. This result indicates that, from the perspective of enhancing the water-blocking property of the resulting asphalt pavement, it is preferable to have a larger amount of the asphalt emulsion. From this perspective, the ratio of the amount of the asphalt emulsion blended with the fine aggregate can be, for example, 30 parts by mass or more of the asphalt emulsion with respect to 100 parts by mass of the fine aggregate, and more preferably, it can be judged that it can be 32 parts by mass or more of the asphalt emulsion with respect to 100 parts by mass of the fine aggregate. Also, based on the content of the evaporation residue in the asphalt emulsion, from the perspective of enhancing the water-blocking property of the tack coat, the content of the evaporation residue of the asphalt emulsion is preferably 15 parts by mass or more, and more preferably 16 parts by mass or more with respect to 100 parts by mass of the fine aggregate. In any case, according to the slurry-like tack coat material containing the fine aggregate and the asphalt emulsion, it was shown that a tack coat capable of imparting excellent water-blocking property to the asphalt pavement can be obtained over a wide range of the mixing ratio of the fine aggregate and the asphalt emulsion.

[0080] <Experiment 9: Pressurized Water Permeability Test> A tack coat was constructed using a slurry-like tack coat material containing various fine aggregates with different particle size distributions and an asphalt emulsion, and the pressurized water permeability of the specimen having the constructed tack coat was evaluated.

[0081] Specifically, as the fine aggregate, except for using a fine aggregate with a maximum particle size of 600 μm and a linear particle size (specimen 9-1), a fine aggregate with a maximum particle size of 1.2 mm and a continuous particle size represented by Fuller's maximum density curve (specimen 9-2), or a fine aggregate with a maximum particle size of 1.2 mm and a linear particle size (specimen 9-3), specimens for the pressurized water permeability test were obtained and the water permeability coefficient was evaluated in the same procedure as described in Experiment 7. The results obtained are shown in Figure 8.

[0082] As shown in Fig. 8, in Specimen 9-2 constructed from a slurry tack coat material containing fine aggregate with a maximum particle size of 1.2 mm and having a continuous particle size represented by Fuller's maximum density curve and an asphalt emulsion, when the finished thickness of the tack coat was 2 mm, the permeability coefficient became 1.0×10 -8 (cm / s) or less, and it became substantially impermeable. In contrast, Specimens 9-1 and 9-3 having a tack coat constructed from a slurry tack coat material containing fine aggregate with a linear particle size showed higher permeability coefficients compared to Specimen 9-2. This result indicates that a tack coat excellent in water permeability resistance can be constructed with a slurry tack coat material containing fine aggregate having a continuous particle size represented by Fuller's maximum density curve as the fine aggregate.

[0083] <Experiment 10: Pore water pressure loading test> The resistance of a tack coat constructed from a tack coat material containing fine aggregate and an asphalt emulsion to pore water pressure loading was evaluated by a test method conforming to the pore water pressure loading test method described in "3. Adhesion evaluation of tack coat between construction layers" of "Hiroki Takebayashi, Hiroki Baba, Minoyuki Chikamatsu, Shigeki Takahashi, Study on evaluation methods for adhesiveness at construction joints and between construction layers, Journal of the Japan Society of Civil Engineers, Series E1 (Pavement Engineering), Vol. 76, No. 2 (Proceedings of Pavement Engineering, Vol. 25), I_217-I_225, 2020". This test is a method for evaluating the influence of water intruding from construction joints, etc. on the reduction of the adhesiveness between layers of the asphalt mixture layer. For example, it is also described in Japanese Patent Application Laid-Open No. 2022-016354.

[0084] The outline of the preparation procedure of the specimen is shown in Fig. 9A, and the outline of the test method is shown in Fig. 9B. More specifically, a perforation was provided in the center of a base specimen (upper limit particle size of surface asphalt mixture type B - modified asphalt for extra heavy load) with dimensions of 300 mm × 300 mm × thickness of 40 mm, a nipple for injecting water into the perforation was installed, and resin was injected and fixed. Then, a slurry - type tack coat material containing 69.8 mass% fine aggregate with a maximum particle size of 1.2 mm, 22.3 mass% cationic modified asphalt emulsion (evaporation residue 50%), 5.6 mass% water, and 2.3 mass% cement was evenly spread with a thickness of 3 mm and cured for 12 hours to construct a tack coat. On the surface of the base specimen with the tack coat constructed, an upper specimen with dimensions of 300 mm × 300 mm × thickness of 40 mm was paved using an asphalt mixture with the same composition as the base specimen, and cured for 12 hours to obtain a specimen for the pore water pressure loading test. Also, as a comparison object, instead of spreading and constructing a tack coat with a slurry - type tack coat material, PKM - T (trade name: Farmzol, manufactured by Nichireki Co., Ltd.), a commercially available tire adhesion - suppressing asphalt emulsion, was sprayed at a spraying rate of 0.4 kg / m 2 (theoretical thickness 0.2 mm), and a specimen for the pore water pressure loading test was obtained in the same manner as the above procedure except that the tack coat was constructed by curing for 12 hours after spraying. The obtained specimen was installed in a testing machine, a water conduit was connected to the above nipple, and from the water conduit, water was intermittently injected at a water injection pressure of 0.5 MPa determined from the contact pressure of a large truck as the condition of waterproof test II in the waterproofing manual for road bridge decks, with a pressurization time of 0.3 seconds and a non - pressurization time of 0.7 seconds, and 1 second per cycle. During this period, the amount of flowing water leaking from between the layers was measured, and the pressurization cycle was repeated until the amount of flowing water reached 1000 g. In the test, test water added with uranine solution was used so that the flowing water path could be confirmed. Since uranine has the property of emitting light when irradiated with a black light, after the test, the specimen was split and the flowing water path could be confirmed by irradiating it with a black light.

[0085] For specimens with a tack coat constructed from commercially available tire adhesion-inhibiting asphalt emulsion PKM-T, the time-dependent changes in the amount of running water leaking from between the layers and the injection pressure are shown in Fig. 10. As shown in Fig. 10, when a tack coat was constructed from commercially available tire adhesion-inhibiting asphalt emulsion PKM-T, once water leakage started from between the layers, the amount of water leakage from between the layers gradually increased and eventually tended to progress to a large amount of water leakage. The average water leakage start time was 57 minutes. Also, the injection pressure gradually decreased over time. The decrease in the injection pressure means that a pressure escape path was formed and it was gradually expanding, suggesting that the adhesion between the layers was broken due to the load of pore water pressure in the specimen with a tack coat constructed from commercially available tire adhesion-inhibiting asphalt emulsion PKM-T.

[0086] On the other hand, for specimens with a tack coat constructed from a slurry-like tack coat material containing fine aggregate and asphalt emulsion, the time-dependent changes in the amount of running water leaking from between the layers and the injection pressure are shown in Fig. 11. In specimens with a tack coat constructed from a slurry-like tack coat material containing fine aggregate and asphalt emulsion, the average water leakage start time was 184 minutes, which was later than that of specimens with a tack coat constructed from commercially available tire adhesion-inhibiting asphalt emulsion PKM-T. This result suggests that the tack coat constructed from a slurry-like tack coat material containing fine aggregate and asphalt emulsion adheres to the layers between more densely and firmly. On the other hand, in specimens with a tack coat constructed from the said slurry-like tack coat material, once water leakage started from between the layers, it immediately tended to progress to a large amount of water leakage. Surprisingly, however, the injection pressure hardly changed over time. This result indicates that in specimens with a tack coat constructed from a slurry-like tack coat material containing fine aggregate and asphalt emulsion, the progress of adhesion break between the layers due to the load of pore water pressure was not observed.

[0087] As described above, in the specimens with tack coats constructed from slurry-like tack coat materials containing fine aggregates and asphalt emulsion, and in the specimens with tack coats constructed from PKM-T, a commercially available tire adhesion-inhibiting asphalt emulsion, differences were observed in the water leakage behavior under the load of pore water pressure. This was considered to be based on the difference in the resistance to the separation of interlayer adhesion due to the load of pore water pressure. Therefore, the flow path of water in the specimens after the pore water pressure load test was observed.

[0088] Specifically, an attempt was made to confirm the flow path of water by splitting the specimen between layers after the pore water pressure load test. Fig. 12 shows a photograph of the split surface when a black light was irradiated on the split surface between layers of a specimen with a tack coat constructed from PKM-T, a commercially available tire adhesion-inhibiting asphalt emulsion, after the pore water pressure load test. As shown in Fig. 12, it was confirmed that water leakage occurred in almost all directions in the specimen with a tack coat constructed from PKM-T. This result indicates that in the specimen with a tack coat constructed from PKM-T, the separation of the interlayer adhesion has progressed in all directions.

[0089] On the other hand, the specimen with a tack coat constructed from a slurry-like tack coat material could not be split between layers even when an attempt was made to split it after the pore water pressure load test. This result indicates that in the specimen with a tack coat constructed from a slurry-like tack coat material, the interlayer is still strongly adhered and the separation of the interlayer adhesion has not progressed.

[0090] In addition, the specimen with the tack coat constructed from the slurry-like tack coat material could not be torn even when it tried to tear between layers after the implementation of the pore water pressure loading test. Therefore, as shown in Fig. 13, the specimen was cut in a direction perpendicular to the tack coat surface, and its cross-section was observed to confirm the water flow path. Then, in the specimen with the tack coat constructed from the slurry-like tack coat material, water leakage occurred concentratedly from only a limited part of the path around the coarse aggregate, and no water leakage was observed in all directions as observed in the specimen with the tack coat constructed from PKM-T. This result indicates that in the specimen with the tack coat constructed from the slurry-like tack coat material containing fine aggregate and asphalt emulsion, no serious adhesion failure due to the load of pore water pressure occurred, and it has interlayer adhesiveness.

[0091] From the above results, it was shown that the tack coat constructed from the tack coat material containing fine aggregate and asphalt emulsion exhibited excellent resistance to pore water pressure loading compared to the tack coat constructed from PKM-T, which is a commercially available tire adhesion suppression type asphalt emulsion.

[0092] <Experiment 11: Adhesion Strength after Pore Water Pressure Loading Test> In Experiment 10, it was suggested that the tack coat constructed from the tack coat material containing fine aggregate and asphalt emulsion had adhesiveness even after the load of pore water pressure. Therefore, the tensile adhesion strength and shear adhesion strength of the specimen after the pore water pressure loading test was conducted in Experiment 10 were measured to evaluate the adhesiveness of the tack coat after the load of pore water pressure in more detail. The tensile adhesion test was conducted under the conditions of a test temperature of 23°C and a tensile speed of 60 mm / min, while the shear adhesion test was conducted under the conditions of a test temperature of 23°C and a tensile speed of 1 mm / min. The tensile adhesion strength and shear adhesion strength were measured, and the failure mode was observed. The obtained results are shown in Fig. 14.

[0093] As shown in Fig. 14A, the tensile adhesion strength of the specimen after the pore water pressure loading test was approximately 1.05 MPa, indicating that it had excellent tensile adhesion strength even after the pore water pressure was loaded. Also, the failure mode at the time of tensile failure was cohesive failure of the asphalt mixture layer or cohesive failure of the tack coat, and interfacial failure at the interface between the asphalt mixture layer and the tack coat was not observed. This result shows that the tack coat constructed from the slurry-type tack coat material containing fine aggregate and asphalt emulsion maintains sufficient adhesive strength even after the pore water pressure is loaded.

[0094] On the other hand, as shown in Fig. 14B, the shear adhesion strength of the specimen after the pore water pressure loading test was approximately 0.6 MPa, indicating that it had excellent shear adhesion strength even after the pore water pressure was loaded. Also, the failure mode at the time of shear failure was cohesive failure of the asphalt mixture layer or cohesive failure of the tack coat, and again, interfacial failure at the interface between the asphalt mixture layer and the tack coat was not observed. This result shows that the tack coat constructed from the slurry-type tack coat material containing fine aggregate and asphalt emulsion maintains sufficient adhesive strength even after the pore water pressure is loaded.

[0095] From the above results, it was shown that the tack coat constructed from the slurry-type tack coat material containing fine aggregate and asphalt emulsion exhibits excellent resistance to pore water pressure loading.

Industrial Applicability

[0096] As described above, according to the tack coat material according to one aspect of the present invention, a tack coat with suppressed stickiness can be quickly constructed, and peeling of the tack coat can be significantly reduced. Also, according to the tack coat material according to one aspect of the present invention, a tack coat having excellent resistance to water pressure loading can be constructed. The industrial applicability of the present invention, which contributes to both the stability of the resulting pavement and the reduction of the burden on workers, is very great.

Claims

1. Fine aggregate, an asphalt emulsion, and a slurry-like tack coat material containing the same.

2. The tack coat material according to Claim 1, wherein the content of the evaporation residue of the asphalt emulsion is 15 parts by mass or more and 19 parts by mass or less when the content of the fine aggregate is 100 parts by mass.

3. The tack coat material according to Claim 1 or 2, wherein the fine aggregate has a maximum particle size of 0.6 mm or more and 1.8 mm or less.

4. The tack coat material according to Claim 3, wherein the applied thickness is 1 mm or more and 4 mm or less.

5. A step of spreading a slurry-like mixture containing fine aggregate and an asphalt emulsion on a construction surface, and a step of laying an asphalt mixture layer on the construction surface on which the mixture has been spread and a method for constructing an asphalt pavement including the same.

6. The method for constructing an asphalt pavement according to Claim 5, wherein the content of the evaporation residue of the asphalt emulsion is 15 parts by mass or more and 19 parts by mass or less when the content of the fine aggregate in the mixture is 100 parts by mass.

7. The method for constructing an asphalt pavement according to Claim 5 or 6, wherein the fine aggregate has a maximum particle size of 0.6 mm or more and 1.8 mm or less.

8. The method for constructing an asphalt pavement according to Claim 7, wherein the mixture is spread so that the applied thickness is 1 mm or more and 4 mm or less.

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