Manufacturing method of pavement structure

Abstract

To provide a manufacturing method of a pavement structure that can achieve a sufficient degree of compaction even if compacting time is short.SOLUTION: A manufacturing method of a pavement structure according to the present invention includes spraying foam water during subbase layer compaction. In one embodiment of the manufacturing method of a pavement structure, the foam water is an aqueous solution of a surfactant. In one embodiment of the manufacturing method of a pavement structure, the foam water is microbubble-containing water. In one embodiment, the pavement structure according to the present invention is an asphalt structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a pavement structure. [Background technology]

[0002] BACKGROUND ART Most pavement structures such as roads are manufactured by forming a roadbed layer on a subgrade layer, and then laminating a surface layer of the pavement structure on top of that.

[0003] The roadbed layer is generally a ground surface made of soil, and for example, a bank of earth with a flat, leveled top surface, or a flat surface made by scraping away mountains or hills, etc. can be used.

[0004] The roadbed layer may contain two layers, an upper roadbed layer and a lower roadbed layer, and generally the lower roadbed layer is made of crushed stone or the like with no adjusted grain size, while the upper roadbed layer is made of roadbed material with adjusted grain size, such as crushed stone or crushed run. When the roadbed layer is made of a single layer, it can be made of roadbed material with adjusted grain size.

[0005] Regarding the surface layer, in the case of an asphalt pavement structure, a base layer is usually laminated between the surface layer and the subgrade layer. In this case, for example, the base layer can be made of a coarse-graded asphalt mixture and the surface layer can be made of a dense-graded asphalt mixture. Such an asphalt pavement structure is disclosed, for example, in Patent Document 1.

[0006] In the case of a concrete pavement structure, for example, an asphalt intermediate layer can be laminated on a roadbed layer, and a surface layer made of concrete slabs can be laminated on top. An example of such a concrete pavement structure is the structure described in Patent Document 2.

[0007] When forming each of these layers, the materials must be spread evenly and then compacted with a roller. When forming the roadbed layer, water may be sprayed while compacting to prevent dust from being generated. When forming the surface layer, a chemical may be sprayed onto the roller while compacting to prevent asphalt from adhering to the roller. An example of such a roller is a machine described in Patent Document 3. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2023-016121 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-203163 [Patent Document 3] Japanese Patent Publication No. 2022-181446 Summary of the Invention [Problem to be solved by the invention]

[0009] It is extremely important that construction of pavement structures, especially renovation work, be completed in a short time. However, when compacting, it is sometimes necessary to take the time necessary to achieve the required degree of compaction.

[0010] Therefore, the present invention provides a method for manufacturing a pavement structure that can achieve a sufficient degree of compaction even when rolling is carried out for a short period of time. [Means for solving the problem]

[0011] The present inventors have discovered that the above-mentioned problems can be solved by a method for manufacturing a pavement structure having the following features.

[0012] That is, the present invention has the following aspects: <<Aspect 1>> A method for producing a pavement structure, comprising spraying foam water during compaction of a subgrade layer. <<Aspect 2>> 2. The method of claim 1, wherein the foamed water is an aqueous solution of a surfactant. Aspect 3 2. The method for producing a pavement structure according to claim 1, wherein the foamed water is water containing microbubbles. Aspect 4 2. The method for producing a pavement structure according to claim 1, wherein the pavement structure is an asphalt structure. [Effects of the Invention]

[0013] According to the present invention, a method for manufacturing a pavement structure can be provided that allows rolling compaction to be performed in a short period of time. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 shows one embodiment of a layer configuration for a pavement structure. DETAILED DESCRIPTION OF THE INVENTION

[0015] <<Method for manufacturing pavement structure>> The method for manufacturing a pavement structure of the present invention includes spraying foam water during compaction of the roadbed layer. The inventors have discovered that spraying foam water during compaction of the roadbed layer facilitates compaction of the roadbed materials, such as crushed stone, that make up the roadbed layer. This is thought to be because foam water reduces friction between the roadbed materials, making it easier for the crushed stone to move to a densely packed position when pressure is applied by a roller. This allows the roadbed material to be effectively compacted, reduces the number of times the roller makes back and forth movement to the area to be compacted, and enables compaction to be completed in a short time.

[0016] 1 shows one embodiment of the layer configuration of a pavement structure 100. The manufacturing method of the present invention will be described below based on this embodiment, but the pavement structure 100 manufactured by the manufacturing method of the present invention is not limited to this embodiment.

[0017] A method of manufacturing the pavement structure 100 may include constructing the subgrade layer 10 .

[0018] The roadbed layer 10 is generally made of soil, but concrete decks, steel decks, etc. can also be used. In the case of a soft roadbed, such as one with a CBR of less than 3, it can be strengthened by introducing embankment to a thickness of about 50 cm to 100 cm, or by stabilizing the soft ground with lime, cement, etc. For example, the roadbed layer 10 can be constructed by excavating the existing ground to a predetermined depth using an excavating machine such as a hydraulic excavator, then leveling the top surface of the ground using a leveling vehicle such as a bulldozer, and then compacting the surface with a compacting vehicle such as a tire roller, thereby constructing the roadbed layer 10.

[0019] The method of manufacturing the pavement structure 100 then includes forming a subbase layer 20 on top of the subgrade layer 10 .

[0020] This step may include providing a roadbed material on the roadbed layer 10 and compacting the roadbed material, and spraying foam water during the compacting step.

[0021] For example, the roadbed layer 20 can be formed by constructing the roadbed layer 10, then spreading roadbed material transported by dump truck on the top surface of the roadbed layer 10 using a leveling vehicle such as a motor grader, and compacting it with a roller while spraying foaming water.

[0022] The process of forming the roadbed layer 20 may include a process of forming a lower roadbed layer 21 on the roadbed layer 10 and a process of forming an upper roadbed layer 22 on the lower roadbed layer 21, and each process may include a process of providing a roadbed material and a process of compacting the roadbed material while spraying foaming water. Note that a process of stacking another layer between the lower roadbed layer 21 and the upper roadbed layer 22 may also be included, and for example, a process of stacking an asphalt reinforcing layer as described in Patent Document 1 may be included.

[0023] The thickness of the roadbed layer 20 may be, for example, 10 cm or more, 20 cm or more, or 30 cm or more, and may be 100 cm or less, 80 cm or less, 60 cm or less, or 40 cm or less. The thickness of the lower roadbed layer 21 may be, for example, 5 cm or more, 10 cm or more, or 20 cm or more, and may be 50 cm or less, 30 cm or less, or 20 cm or less. The thickness of the upper roadbed layer 22 may be, for example, 10 cm or more, 20 cm or more, or 30 cm or more, and may be 80 cm or less, 60 cm or less, or 40 cm or less.

[0024] The roadbed material may be granular materials such as crushed stone, gravel, slag, recycled aggregate, sand, crusher run, crusher run steel slag, recycled crusher run, or clinker ash, or a mixture of these materials with stabilizers such as cement, lime, or asphalt. Furthermore, when the roadbed layer 20 is a single layer, the roadbed material for the upper roadbed layer 22 may be made of these granular materials with adjusted particle size. Materials that do not contain asphalt may also be used as the roadbed material.

[0025] The foam water is not particularly limited as long as it can reduce friction between roadbed materials such as crushed stone, but may be an aqueous solution of a surfactant, water containing microbubbles, or the like.

[0026] The surfactant may be an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, etc. These surfactants may be used alone or in combination of two or more.

[0027] Examples of anionic surfactants include fatty acid salts, higher alcohol sulfates, alkylbenzenesulfonates and alkylnaphthalenesulfonates, polyoxyethylene sulfate salts, and fluorine-containing anionic surfactants.

[0028] Examples of cationic surfactants include amine salts, alkyltrimethylammonium salts, dialkyldimethylammonium salts, and hydroxyl group-containing ammonium salts.

[0029] Examples of nonionic surfactants include polyoxyethylene higher alcohol ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene sorbitan fatty acid esters, phosphate esters, fluorine-containing nonionic surfactants, sugar esters, and cellulose ethers.

[0030] Examples of amphoteric surfactants include fatty acid type amphoteric surfactants, sulfonic acid type amphoteric surfactants, and alkylglycines.

[0031] Microbubble-containing water can be prepared using a microbubble generator. Microbubbles are defined as bubbles with a diameter of approximately 100 μm or less, including bubbles with a diameter of less than 1 μm.

[0032] Microbubble generators that can be used include various types of generators, such as swirling flow type, Venturi type, micropore type, static mixer type, pressurized dissolution deposition type, heated deposition type, steam direct contact condensation type, surfactant-added micropore type, ultrasonic cavitation, etc. The microbubble generator may be attached to a sprayer that sprays foaming water, and microbubble-containing water may be prepared and sprayed on-site by the sprayer, or microbubble-containing water prepared elsewhere may be sprayed from the sprayer.

[0033] The foam water may be sprayed directly onto the roadbed material, or indirectly onto the roadbed material by providing foam water to the rollers of a roller compactor. The amount of foam water to be sprayed is sufficient to penetrate into the gaps in the roadbed material of the roadbed layer 20, and is preferably an amount that brings the roadbed material close to the optimum moisture content. 0.01 liters / m 2 Over 0.1 liters / m 2 Over 1.0 liters / m 2 or more, or 2.0 liters / m 2 Above 10 liters / m 2 Below 5.0 liters / m 2Below 3.0 liters / m 2 , 2.0 liters / m 2 Less than or equal to 1.0 liters / m 2 The following amounts can be used: For example, the amount of foam water sprayed is 0.01 liters / m 2 More than 10 liters / m 2 The amount can be less than 1.0 L / m 2 More than 5.0 L / m 2 The following is preferred:

[0034] The method for spraying the foam water is not particularly limited, but may be carried out, for example, from a water sprinkler or liquid sprayer attached to the roller, or may be sprayed automatically or manually using a liquid sprayer or the like separate from the roller.

[0035] A method for manufacturing the pavement structure 100 may include forming a surface layer 30 over a subbase layer 20 .

[0036] In the asphalt pavement structure 100, in simple paving carried out on roads with low traffic volume or traffic load, the surface course 30 can be formed directly on the roadbed layer 20, but in normal paving carried out on roads with relatively high traffic volume or traffic load, a base course 40 can be formed between the roadbed layer 20 and the surface course 30. In addition, other layers can be formed between these layers, and other layers such as a wearing layer can be formed on the surface course 30.

[0037] In the asphalt pavement structure 100, both the surface layer 30 and the base layer 40 can be formed from an asphalt mixture containing at least asphalt and aggregate. The aggregate particle size of the base layer 40 can be different from that of the surface layer 30; for example, the aggregate particle size of the base layer 40 can be coarser than that of the surface layer 30. For example, the asphalt mixture for the base layer 40 can be a coarse-grained asphalt mixture containing coarse aggregate such as crushed stone, and the asphalt mixture for the surface layer 30 can be a dense-grained asphalt mixture containing fine aggregate such as river sand or crushed sand.

[0038] The asphalt mixture that constitutes the surface layer 30 and the base layer 40 may be a cold asphalt mixture, but it can also be a heated asphalt mixture, which has better durability than a cold asphalt mixture. For example, the surface layer 30 and the base layer 40 can be formed by spreading a heated asphalt mixture that has been heated to, for example, about 150 to 170°C, and then compacting it uniformly with a rolling machine.

[0039] The total thickness of the surface layer 30 and the base layer 40 can be changed depending on the traffic volume or traffic load of the asphalt pavement structure 100, but may be, for example, 5 cm or more, 10 cm or more, or 20 cm or more, or 50 cm or less, 30 cm or less, or 20 cm or less. The thickness of each of the surface layer 30 and the base layer 40 may be half of this total thickness.

[0040] In the concrete pavement structure 100, in addition to the concrete slab that forms the surface course 30, an asphalt intermediate layer 40 can be formed between the roadbed layer 20 and the surface course 30. Other layers can also be formed between these layers.

[0041] The type of concrete slab is not particularly limited, and may be, for example, a concrete slab made of ordinary concrete pavement, in which concrete is spread evenly within a formwork by hand or the like and then compacted using a vibrator or the like, a concrete slab made of continuous reinforced concrete pavement with reinforcing bars, or a concrete slab made of compacted concrete pavement, which is made using a roller compactor like asphalt pavement.

[0042] The total thickness of the concrete slab can vary depending on the traffic volume or traffic load of the concrete pavement structure 100, but may be, for example, 5 cm or more, 10 cm or more, or 20 cm or more, or 50 cm or less, 30 cm or less, or 20 cm or less.

[0043] For the asphalt intermediate layer 40, a coarse-graded asphalt mixture, a dense-graded asphalt mixture, etc. can be used, but it is preferable to use a dense-graded asphalt mixture.

[0044] The thickness of the asphalt intermediate layer 40 may be, for example, 2 cm or more, 3 cm or more, or 5 cm or more, or may be 20 cm or less, 10 cm or less, or 5 cm or less. When the asphalt intermediate layer 40 is used, the thickness of the roadbed layer 20 can be reduced accordingly.

[0045] The pavement structure 100 can be used for a variety of purposes, such as pavement for general roads, airports, truck terminals, port container yards, general material storage yards, etc. [Explanation of symbols]

[0046] 10 Subgrade layer 20 Subgrade layer 21 Lower subbase layer 22 Upper subbase layer 30 Surface layer 40 base layer, asphalt interlayer 100 Pavement structure

Claims

1. A method for producing a pavement structure, comprising spraying foam water during compaction of a subgrade layer.

2. The method of claim 1 , wherein the foamed water is an aqueous solution of a surfactant.

3. The method for producing a pavement structure according to claim 1 , wherein the foamed water is water containing microbubbles.

4. The method for manufacturing a pavement structure according to claim 1 , wherein the pavement structure is an asphalt structure.

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