JP2008002197A - Elastic pavement material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology of enhancing durability at a high temperature in summer and skid resistance, in an elastic pavement material concurrently using an EVA as a thermoplastic binder and asphalt. <P>SOLUTION: This elastic pavement material contains: an asphalt-based binder containing asphalt and an ethylene-vinyl acetate copolymer; rubber chips and/or rubber powder; and an aggregate. The elastic pavement material contains foamed and solidified silica sand which is composed of particulate silica sand and a urethane binder. Preferably, the particle diameter of the foamed and solidified silica sand is in a range of 3-10 mm, and the average particle diameter of the particulate silica sand for use is in a range of about 10-500 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an elastic pavement, and more particularly, to an elastic pavement using a thermoplastic binder.

  Conventionally, as a low-noise pavement for reducing traffic noise, there is a porous drainage pavement in which a gap is provided inside the pavement using a large particle size aggregate. Also known is a low noise elastic pavement using vulcanized rubber in powder or chip form and using a curable resin such as urethane or epoxy as a binder.

  Among them, elastic pavement using rubber chips has excellent effects such as shock absorption during walking and safety during falls due to the elasticity of rubber chips, and since it has voids inside, it has drainage and breathability. In addition, it has excellent sound absorption and is therefore effective in reducing noise generated on tires and road surfaces. Therefore, it is attracting attention as a functional elastic pavement for reducing traffic noise in urban areas.

  However, when a curable resin such as urethane is used as a binder, there is a problem in that when the applied pavement is recycled, it cannot be reused by heating or the like like asphalt. In addition, because curing is slow at room temperature, it takes about 1 to 2 days for curing time, and there is a problem that traffic must be restricted during that time. It was difficult and had economic problems.

On the other hand, the applicant of the present invention has studied various types of elastic pavement using asphalt as a binder that can be constructed in a short time and can be recycled at low cost instead of conventional curable binders such as urethane and epoxy. An elastic pavement material using an ethylene vinyl acetate copolymer (EVA), which is a thermoplastic resin, as a binder with asphalt has been proposed (for example, Patent Documents 1 and 2). For example, Patent Document 3 is formed using an elastic aggregate, a hard aggregate, and a binder for the purpose of providing a porous elastic pavement that can maintain slip resistance performance when wet. In a porous elastic pavement, a technique is disclosed that uses an agglomerated hard aggregate made of an aggregated binder obtained by aggregating and binding a number of hard aggregates with a binder as a hard aggregate.
Japanese Patent Application No. 2004-38513 Japanese Patent Application No. 2005-004509 JP 2006-089942 A (Claims etc.)

  However, elastic pavement using a curable resin such as urethane is thermosetting and has no temperature dependence, whereas elastic pavement using EVA and asphalt in combination uses a thermoplastic binder. When the pavement temperature increases at high temperatures in summer, there is a problem that the strength decreases. In addition, the elastic pavement has a problem that the slip resistance (wet μ) in a wet state such as rainy weather is low, and it has been desired to solve this problem.

  Therefore, an object of the present invention is to provide a technique capable of improving durability at high temperatures in summer and improving slip resistance in an elastic pavement using EVA and asphalt which are thermoplastic binders in combination. .

  It is considered that the decrease in strength at high temperatures in summer is a fate in pavement using a thermoplastic binder. Therefore, as a result of intensive studies, the present inventors have reduced the temperature of the road surface even at high temperatures in summer by mixing the fine silica sand foamed and solidified with a binder into the pavement as a water retaining material. It was found that it is possible to suppress the decrease in pavement strength, and that the mixing effect of the foamed solidified silica sand can also provide an effect of suppressing the aging degradation of wet μ, It came to be completed.

  That is, the elastic pavement of the present invention is a fine silica sand containing an asphalt binder containing asphalt and an ethylene vinyl acetate copolymer (EVA), rubber chips and / or rubber powder, and an aggregate. It contains foamed solidified silica sand and urethane binder.

  In the present invention, the foamed and solidified silica sand preferably has a particle size of 3 to 10 mm, and the fine silica sand has an average particle size of preferably 10 to 500 μm. Moreover, it is preferable that content of the said foaming solidified silica sand shall be 5 to 20% by volume ratio with respect to the total amount of the said asphalt binder, a rubber chip and / or rubber powder, and an aggregate. Furthermore, the weight ratio between the fine silica sand and the urethane binder is preferably in the range of 30/70 to 50/50, and the porosity of the foam-solidified silica sand is in the range of 5 to 60%. It is preferable to do.

  According to the present invention, the foamed solidified silica sand is filled as a water retention material, so that the elastic pavement using EVA and asphalt, which are thermoplastic binders, can reduce the road surface temperature at high temperatures in summer. In addition to improving durability, it has become possible to achieve good slip resistance.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The elastic pavement of the present invention contains an asphalt-based binder containing asphalt and EVA, rubber chips and / or rubber powder, and aggregate, and together with these, foamed solidification comprising fine silica sand and urethane binder It is characterized in that it contains silica sand.

  By including such foamed solidified silica sand, voids in the elastic pavement can be increased, and this acts as a water retention material, so that the effect of reducing the road surface temperature can be obtained even at high temperatures in summer. As a result, the road surface strength can be prevented from being lowered and the durability in summer can be improved. Further, the foamed solidified silica sand according to the present invention also acts as an aggregate, but the normal aggregate is peeled off from the pavement surface due to friction with a tire or the like, whereas the foamed solidified silica sand is finely ground silica. Since it is a combined body of sand, even if part of it is scraped off due to wear, the fine silica sand inside is newly exposed and the function as an aggregate can be exhibited. Therefore, according to the present invention, it is possible to suppress the aging degradation of the slip resistance due to the dropping of the aggregate.

  The particle size of the foamed solidified silica sand is not particularly limited, but is preferably in the range of 3 to 10 mm. If the particle size of the foamed solidified silica sand is too small, the water retention is reduced, and if it is too large, the aggregate tends to fall off, which is not preferable.

  Moreover, it is preferable that the compounding quantity with respect to the elastic pavement of foaming solidified silica sand shall be in the range of 5 to 20% by volume ratio with respect to the total amount of an asphalt binder, rubber | gum, and aggregate. If the blended amount of the foamed solidified silica sand is too small, the water retention effect may be insufficient, and if it is too large, the elasticity becomes insufficient, which is not preferable.

  The foamed solidified silica sand according to the present invention is obtained by bonding fine silica sand with a urethane binder, and has a void inside by foaming and solidifying a urethane binder mixed with the fine silica sand, It becomes an aggregate with water retention. In order to obtain the foamed solidified silica sand having the above particle diameter, after appropriately producing foamed solidified silica sand, it may be cut by a cutting machine or the like to be adjusted to a desired size.

  As the fine silica sand to be used, those having an average particle diameter in the range of 10 to 500 μm, particularly 40 to 200 μm can be suitably used. If the average particle size of the fine silica sand is too small, the construction becomes difficult, and if it is too large, the water retention cannot be maintained. Further, the urethane binder is not particularly limited, but for example, as a two-component urethane binder, preferably an isocyanate group terminal prepolymer and a polyol in an equivalent ratio of hydroxyl group / isocyanate group, for example, 0.2 What was mixed by -0.8 can be used suitably.

  As an example of the isocyanate-terminated prepolymer of such a two-component urethane binder, the isocyanate content is 5 to 25%, the viscosity is 1000 to 5000 cP (25 ° C.), and the average number of functional groups of the isocyanate-terminated prepolymer is 2 to 3. Is mentioned. Examples of the isocyanate for the prepolymer include diphenylmethane diisocyanate polyisocyanate. As the active hydrogen compound used for modification, polyalkylene glycol having a molecular weight of about 1000 to 3000 is usually used.

  On the other hand, as an example of the polyol, it is preferable that the average number of functional groups is 2 to 6, the average molecular weight is 1000 or less, and more than half of the hydroxyl groups are primary hydroxyl groups from the viewpoint of reactivity. Examples include glycol, diethylene glycol, and polyalkylene ether glycol.

  The weight ratio between the fine silica sand and the urethane binder in the foamed solidified silica sand is preferably in the range of 30/70 to 50/50, and the porosity is adjusted in the range of 5 to 60%. It is preferable to do.

  The asphalt that can be used in the present invention is not particularly limited, and conventional asphalt, for example, straight asphalt, semi-blown asphalt, blown asphalt, asphalt emulsion, cutback added with tar, pitch, oil, etc. Examples include asphalt and recycled asphalt. These can be used alone or in combination of two or more. The asphalt may be decolorized asphalt. The preferred amount of asphalt in the asphalt binder according to the present invention is in the range of 20 to 70% by weight.

  Moreover, as EVA, it does not restrict | limit in particular, What can be obtained in a market can be used conveniently. In particular, high molecular weight compounds having a weight average molecular weight of 50,000 to 100,000 are suitable, and more preferably, the Vicat softening point according to JIS K7206 is 40 ° C. or higher and 120 ° C. or lower, particularly 50 ° C. or higher and 80 ° C. The one having a melt mass flow rate in accordance with JIS K7206 within a range of 1 to 100 g / 10 min, particularly 5 to 30 g / 10 min is used. Specifically, for example, EVA530, EVA541, EVA625, EVA633 (all manufactured by Tosoh Corporation) and the like can be suitably used.

  Further, the vinyl acetate unit in EVA is preferably 10% by weight or more in order to enhance the adhesion to rubber, and the durometer A hardness in accordance with EVA JIS K7215 is 70 or more in terms of strength. Is preferred. The suitable amount of EVA in the asphalt binder according to the present invention is in the range of 30 to 80% by weight.

  In addition to the asphalt and EVA, the asphalt binder according to the present invention preferably contains a wax. Such wax is not particularly limited, and any of natural wax and synthetic wax such as petroleum wax can be used. For example, paraffin wax, microcrystalline wax, liquid paraffin wax, paraffinic synthetic wax, polyethylene wax And hydrocarbon waxes, but are not limited to these. Such waxes may be used alone or in combination of two or more. The wax used in the present invention preferably has a softening point of 80 ° C. or higher and 160 ° C. or lower, particularly 90 ° C. or higher and 130 ° C. or lower. Further, the penetration at 25 ° C. is preferably 20 or less, more preferably 8 or less. The blending amount of the wax in the asphalt binder of the present invention is preferably 10 to 60% by weight.

  Further, the asphalt binder according to the present invention preferably further contains a silane coupling agent, and this also provides the adhesion of the stone surface, so that the durability can be further enhanced. As the silane coupling agent, those available in the market can be used as appropriate, and are not particularly limited. Among them, amino-based silane coupling agents are suitable, for example, Shin-Etsu Silicone Co., Ltd. KBM603, KBM903, etc. which can be manufactured can be used conveniently. As a compounding quantity of a silane coupling agent, it can be set as about 0.5 to 5 weight% with respect to all the binders, for example.

  In addition, other thermoplastic elastomers can be added to the asphalt binder, for example, in order to improve strength and the like. Examples of such other thermoplastic elastomers include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), and styrene-ethylene-butylene-styrene copolymer (SEBS). One type or a combination of two or more types can be appropriately selected and used. The compounding quantity of these other thermoplastic elastomers can be about 10-50 weight% with respect to all the binders, for example. Further, in order to improve the workability, about 1 to 40% by weight of low molecular weight petroleum resin may be contained in the asphalt binder.

  The proportion of the asphalt binder in the elastic pavement of the present invention can be about 10 to 35% by volume.

  The material of the rubber chip and / or rubber powder is not particularly limited, and natural rubber, isoprene rubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene rubber, or the like can be used. Such rubber can be obtained from used waste materials such as rubber tires, weather strips, hoses, etc., unnecessary end materials generated during molding, molding defects, and the like.

  The proportion of rubber in the elastic pavement of the present invention is preferably 20 to 70% by volume. If this proportion is less than 20% by volume, the effect as an elastic pavement is not sufficient. On the other hand, if it exceeds 70% by volume, sufficient physical properties for application to asphalt pavement cannot be obtained, which is not preferable.

  Moreover, there is no restriction | limiting in particular as an aggregate used for this invention, Recycled aggregates, such as natural aggregates, such as river gravel and river sand, and crushed stone, slag, concrete, glass, and FRP, can be used. The stone, sand, and the like used for the aggregate are for ensuring the strength and wear resistance of the completed pavement and for exposing to the surface to obtain an anti-slip effect. The stone materials preferably have a function of meshing with each other to disperse the load. For this reason, a sharp object such as a crushed stone is suitable. Further, it is preferable to mix 5% by volume or more of fine aggregate having a particle size of 0.5 mm or less with respect to coarse aggregate having a particle size of 0.5 to 30 mm. As the coarse-grained aggregate, a hard one having a sharp shape like a crushed stone that meshes with each other to form a gap is suitable. On the other hand, the fine-grained aggregate adheres to the surface of the large-sized coarse-grained aggregate and brings about an anti-slip action (polishing effect like sandpaper) on the tire or the like.

  The proportion of aggregate in the elastic pavement of the present invention is preferably 35 to 55% by volume. If this proportion is less than 35% by volume, the strength is not sufficient. On the other hand, if it exceeds 55% by volume, sufficient elasticity and bass effect cannot be obtained, which is not preferable.

  The oil used for mixing the above components constituting the elastic pavement is not particularly limited. For example, among petroleum oils composed of three compositions of an aromatic ring, a naphthene ring, and a paraffin chain, the ring analysis result is 36. Aromatic oils having an aromatic carbon content of at least% can be suitably used.

  The elastic pavement of the present invention is a mixture of asphalt, EVA and, if desired, the remaining compound such as wax, aggregate, rubber chips and / or rubber powder mixed at about 150 to 200 ° C., and thereafter The foamed solidified silica sand is put into this mixture and mixed again. In this case, it is preferable to pre-mix EVA and rubber chips and / or rubber powder, and then mix the remaining compound, so that the rubber can be effectively protected from heat.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Example)
20 parts by weight of asphalt (25 ° C. penetration 60-80), 40 parts by weight of EVA (EVA 625, manufactured by Tosoh Corporation) and 40 parts by weight of wax (manufactured by Nippon Seiki Co., Ltd., FT100) are mixed at 180 ° C. Asphalt-based binder was prepared by stirring at.

  Moreover, as a water retention material, fine silica sand (average particle size 80 μm) and urethane binder (manufactured by Nippon Polyurethane Industry Co., Ltd., main agent (RB08) / curing agent (Hex-2) = 95/5 (weight ratio)) Mixing was performed at a weight ratio of 80/20, and the mixture was put into an oven at 60 ° C., and foamed and solidified to produce foamed solidified silica sand. The porosity of the obtained foamed solidified silica sand was 30%. This was cut into a particle size of 3 to 10 mm with a cutter.

  25% by volume of the prepared asphalt binder, 75% by volume of a 75/25 volume ratio of rubber chips (particle size 3 to 5 mm) and aggregate (silica sand) are mixed, and the foamed solidified silica sand is further mixed. The mixture was mixed 10% by volume with respect to the total amount of these mixtures, put into a mixer heated to 180 ° C., stirred for 20 minutes, and then produced an elastic pavement with a porosity of 20% and a thickness of 25 mm. Example elastic pavement samples were used.

(Comparative example)
An elastic pavement sample of a comparative example was produced in the same manner as in the example except that foamed solidified silica sand was not mixed as a water retention material.

  The state of the surface layer of the elastic pavement obtained in the above Examples and Comparative Examples was evaluated together with the general dense-grain pavement as Conventional Example 1 and the urethane-based elastic pavement as Conventional Example 2. The evaluation criteria were “◯” when there was almost no peeling of the surface layer, “Δ” when the unevenness was observed and peeling was confirmed, and “X” when the aggregate was scattered and a large rut was generated. The results are shown in Table 1 below.

＊１）ウレタンバインダー（日本ポリウレタン（株）製 ＲＢ０８：主剤，ＨＥＸ２：硬化剤）２５重量％，ゴム粉（平均粒径４ｍｍ）５６重量％，骨材（混合珪砂，平均粒径１ｍｍ）１９重量％

* 1) Urethane binder (manufactured by Nippon Polyurethane Co., Ltd. RB08: main agent, HEX2: curing agent) 25% by weight, rubber powder (average particle size 4 mm) 56% by weight, aggregate (mixed silica sand, average particle size 1 mm) 19% %

  As a result, the pavement surface temperature in summer (air temperature of about 33 ° C.) decreased by 13 ° C. in an example in which foam solidified silica sand as a water retention material was mixed in an EVA-based elastic pavement at a volume ratio of 10%. Moreover, when the peeling of the surface layer was confirmed, the roughness of the surface layer was reduced as compared with the comparative example in which the water retention material was not filled.

  Next, after the surface layer was peeled, in order to examine the slip resistance in the wet state, a friction evaluation with the rubber sheet in the wet state was performed. As a result, when a force was applied in the lateral direction while pressing the rubber sheet in a wet state, “◯” indicates a case where it hardly moves, “Δ” indicates a case where it moves slightly, and “X” indicates a case where it moves significantly. The results are shown in Table 2 below.

  As a result, it was confirmed that in the example in which the foamed solidified silica sand was mixed in the EVA elastic pavement at a volume ratio of 10%, the slip resistance when wet was improved as compared with the comparative example without mixing. It was.

Claims (6)

In an elastic pavement containing an asphalt binder containing asphalt and an ethylene vinyl acetate copolymer, a rubber chip and / or rubber powder, and an aggregate,
An elastic pavement comprising foamed solidified silica sand comprising fine silica sand and a urethane binder.   The elastic pavement according to claim 1, wherein a particle diameter of the foamed solidified silica sand is within a range of 3 to 10 mm.   The elastic pavement according to claim 1 or 2, wherein an average particle diameter of the fine silica sand is in a range of 10 to 500 µm.   The content of the foamed solidified silica sand is within a range of 5 to 20% by volume with respect to the total amount of the asphalt binder, rubber chip and / or rubber powder and aggregate. The elastic pavement according to one item.   The elastic pavement according to any one of claims 1 to 4, wherein a weight ratio between the fine silica sand and the urethane binder is in a range of 30/70 to 50/50.   The elastic pavement according to any one of claims 1 to 5, wherein the foamed and solidified silica sand has a porosity of 5 to 60%.