Asphalt mixture manufacturing method

Abstract

[Problem] To provide a method for manufacturing an asphalt mixture containing formed asphalt, with which construction for paving is easy even at medium temperature, and a high degree of road rolling can be provided. [Solution] A method for manufacturing an asphalt mixture, the method comprising: a step for adding water to heated asphalt and preparing formed asphalt; and a step for mixing the formed asphalt with an aggregate and a fatty acid compound.

Description

[Technical field]

[0001] The present invention relates to a method for producing an asphalt mixture. [Background technology]

[0002] Asphalt pavement uses an asphalt mixture made by mixing aggregates such as crushed stone and sand with asphalt as a binder. In recent years, as part of efforts to prevent global warming, there has been a demand for lowering (medium-temperature) the mixing temperature when producing asphalt mixtures and the compaction temperature when paving. In addition, there is a demand for the ratio of density (degree of compaction) when the compaction temperature is lowered to the density (reference density) when mixed within the optimal mixing temperature range and compacted at the optimal compaction temperature.

[0003] One of the warm-medium-temperature technologies is the use of foamed asphalt, which is made by mixing heated asphalt with water to create foam, thereby lowering the mixing and compaction temperatures. In asphalt mixtures using foamed asphalt, if the lifespan of the bubbles in the foamed asphalt is short, the properties of the asphalt mixture will not be stable. Therefore, Patent Document 1 proposes a method of extending the foaming time of bubbles by adding an antifoaming agent to the foamed asphalt to make the bubbles finer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6026035 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the foaming time is not extended sufficiently. The present invention provides a method for producing an asphalt mixture containing foamed asphalt, which is easy to apply and can provide a high degree of compaction even when the mixture is heated to medium temperature during paving. [Means for solving the problem]

[0006] [1] A method for producing an asphalt mixture, comprising: adding water to heated asphalt to prepare foamed asphalt; and mixing the foamed asphalt with aggregate and a fatty acid compound. [2] The method for producing an asphalt mixture according to [1], wherein the fatty acid compound is a compound represented by the following formula (II): R 11 -COO-(AO)mR 12 (II) (In the formula, R 11 is a linear, branched or cyclic hydrocarbon group having 1 to 24 carbon atoms which may have a substituent; R 12 represents a hydrogen atom or a methyl group, AO represents a linear or branched oxyalkylene group having 2 to 4 carbon atoms, and m represents the number of moles of the oxyalkylene group added, which is 0 or a number from 1 to 30. [3] In the process of preparing foamed asphalt, a foaming auxiliary is further added, The method for producing an asphalt mixture according to [1], wherein the foaming auxiliary is at least one selected from the group consisting of glycol ether compounds represented by the following formula (I), surfactant compounds, and inorganic compounds: R 1 -O-(AO)nH····(I) (In the formula, R 1 represents a linear, branched or cyclic hydrocarbon group having 1 to 24 carbon atoms which may have a substituent, AO represents a linear or branched oxyalkylene group having 2 to 4 carbon atoms, and n represents the number of moles of the oxyalkylene group added and is a number from 1 to 30. [4] The method for producing an asphalt mixture according to [1], wherein the aggregate contains recycled aggregate. [5] The method for producing an asphalt mixture according to [1], wherein the foaming auxiliary is the glycol ether compound. [6] The method for producing an asphalt mixture described in [1], wherein the step of mixing the aggregate and the fatty acid compound includes mixing the foamed asphalt and the aggregate to obtain a base mixture, and then mixing a fatty acid compound into the base mixture. Effect of the Invention

[0007] According to the method for producing an asphalt mixture of the present invention, in an asphalt mixture containing foamed asphalt, even if the mixture is heated to intermediate temperature during paving, application is easy and a high degree of compaction can be achieved. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a schematic diagram showing an example of an apparatus for producing a base mixture. [Diagram 2] 1 is a graph showing the results of an example. [Diagram 3] 1 is a graph showing the results of an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] FIG. 1 is a schematic diagram showing an example of an apparatus suitable for the method for producing an asphalt mixture according to this embodiment. The apparatus of this embodiment (hereinafter also referred to as this apparatus) is a manufacturing apparatus for adding water and, optionally, a foaming auxiliary to heated asphalt to obtain foamed asphalt, and mixing the obtained foamed asphalt with aggregate to produce a basic mixture.

[0010] This apparatus comprises an asphalt measuring tank 10, a mixing section 20 for mixing water and an optional foaming aid, a foaming section 30 for foaming the asphalt, and a mixer 40 for mixing the foamed asphalt with aggregate.

[0011] Heated asphalt is supplied to the asphalt metering tank 10. The asphalt pump 13 continuously supplies the asphalt in the asphalt metering tank 10 to the foaming section 30 via the asphalt supply pipe 11. The flow meter 14 measures the flow rate of the asphalt flowing through the asphalt supply pipe 11.

[0012] Water and an optional foaming auxiliary are supplied at a predetermined ratio to the mixing section 20. The additive pump 23 continuously supplies an additive liquid containing water and an optional foaming auxiliary to the foaming section 30 via the additive supply pipe 21. The flow meter 24 measures the flow rate of the additive liquid flowing through the additive supply pipe 21.

[0013] In the foaming section 30, an additive liquid containing water and an optional foaming aid is mixed with the heated asphalt, and foaming occurs due to the vaporization and expansion of the water, producing foamed asphalt that optionally contains a foaming aid. The produced foamed asphalt is sprayed through the spray nozzle 35 onto the aggregate filled in the mixer 40. The foamed asphalt and the aggregate are mixed in the mixer 40 to obtain a basic mixture. The mixing temperature in the mixer 40 is preferably 110 to 185°C.

[0014] By further adding a fatty acid compound to the base mixture obtained in this way, raking work can be easily performed even when the surface is heated during paving, and a high degree of compaction can be achieved. This is thought to be because the presence of fatty acid compounds in the asphalt mixture acts as a lubricant for the asphalt mixture, improving its smoothness. It was also found that after compaction, the asphalt mixture becomes easier to compact and the degree of compaction is improved.

[0015] The timing of addition of the fatty acid compound is not particularly limited as long as it is added to the foamed asphalt after the asphalt has been foamed, and it may be added simultaneously with the aggregate, before the aggregate is mixed, or after the aggregate and the foamed asphalt are mixed. Preferably, the fatty acid compound is added to the basic mixture substantially simultaneously with the mixing of the aggregate or after the aggregate and the foamed asphalt are mixed. It has been found that when the fatty acid compound is added in the process of foaming the asphalt to produce foamed asphalt, there is a risk of inhibiting the foaming of the foamed asphalt. This is thought to be because the fatty acid compound functions like an antifoaming agent.

[0016] The fatty acid compound is preferably a compound represented by the following formula (II) (hereinafter also referred to as compound (II)). R 11 -COO-(AO)mR 12 (II) (In the formula, R 11 is a linear, branched or cyclic hydrocarbon group having 1 to 24 carbon atoms which may have a substituent; R 12 represents a hydrogen atom or a methyl group, AO represents a linear or branched oxyalkylene group having 2 to 4 carbon atoms, and m represents the number of moles of the oxyalkylene group added, which is 0 or a number from 1 to 30. In formula (II), R 11 The number of carbon atoms is preferably 6 to 24, more preferably 8 to 20, further preferably 10 to 18, and particularly preferably 12 to 16. In formula (II), m is preferably 0 or an integer of 1 to 25, more preferably 0 or an integer of 1 to 20, and further preferably 0 or an integer of 1 to 15. In formula (II), AO is preferably an oxyethylene group.

[0017] As the fatty acid compound, for example, a fatty acid compound having an iodine value of 50 to 110, 60 to 100, or 70 to 90 can be used. These may be a combination of a plurality of fatty acid compounds, and in this case, the above iodine value refers to the value of the fatty acid compound in which a plurality of compounds are combined. The iodine value of the fatty acid compound is the iodine value measured in accordance with JIS K0070-1992.

[0018] The fatty acid compound represented by formula (II) is preferably a fatty acid, a fatty acid alkyl ester, a fatty acid polyoxyalkylene alkyl ester, or a polyoxyalkylene fatty acid ester, which may be used alone or in combination of two or more selected from these.

[0019] The molecular weight (g / mol) of the fatty acid compound may be, for example, 100 or more, 150 or more, 200 or more, 250 or more, 270 or more, or 280 or more, and may be 500 or less, 450 or less, 400 or less, 350 or less, 330 or less, or 320 or less. When the fatty acid compound is used in combination with multiple compounds, these molecular weights may be weight average molecular weights.

[0020] Compound (II) includes fatty acids: R 11 COOH, fatty acid methyl ester: R 11 COOCH 3 , fatty acid (poly)oxyethylene methyl ester: R 11 COO(CH 2 CH 2 O) m CH 3 , (poly)oxyethylene fatty acid ester: R 11 COO(CH 2 CH 2 O m Examples include H. Specific examples include palmitic acid, palmitic acid methyl ester, palmitic acid (poly)oxyethylene methyl ester (average number of moles added: 1 to 15), (poly)oxyethylene palmitic acid ester (average number of moles added: 1 to 15), stearic acid, stearic acid methyl ester, stearic acid (poly)oxyethylene methyl ester (average number of moles added: 1 to 15), (poly)oxyethylene stearic acid ester (average number of moles added: 1 to 15), oleic acid, oleic acid methyl ester, oleic acid (poly)oxyethylene methyl ester ester (average number of moles added: 1 to 15), (poly)oxyethylene oleate (average number of moles added: 1 to 15), linoleic acid, linoleic acid methyl ester, linoleic acid (poly)oxyethylene methyl ester (average number of moles added: 1 to 15), (poly)oxyethylene linoleate (average number of moles added: 1 to 15), linolenic acid, linolenic acid methyl ester, linolenic acid (poly)oxyethylene methyl ester (average number of moles added: 1 to 15), (poly)oxyethylene linolenate (average number of moles added: 1 to 15).

[0021] The amount of the fatty acid compound added later may be, for example, 0.01 parts by mass or more, 0.03 parts by mass or more, 0.05 parts by mass or more, 0.1 parts by mass or more, 0.3 parts by mass or more, or 0.5 parts by mass or more, or 2.0 parts by mass or less, 1.0 parts by mass or less, 0.5 parts by mass or less, 0.3 parts by mass or less, 0.2 parts by mass or less, or 0.1 parts by mass or less, relative to 100 parts by mass of the basic mixture containing the aggregate. The amount of the fatty acid compound added later may be, for example, 0.01 parts by mass or more and 2.0 parts by mass or less, 0.03 parts by mass or more and 0.5 parts by mass or more, or 0.05 parts by mass or more and 0.3 parts by mass or less, relative to 100 parts by mass of the basic mixture containing the aggregate.

[0022] Examples of asphalt used in this embodiment include straight asphalt, polymer-modified asphalt, and light-colored (bleached) asphalt.

[0023] In the method of the present invention, a foaming aid can be further added in the step of preparing foamed asphalt. The foaming aid used in this embodiment is at least one selected from the group consisting of glycol ether compounds represented by the following formula (I) (hereinafter also referred to as compound (I)), fatty acid compounds, surfactant compounds, and inorganic compounds. R 1 -O-(AO)nH····(I) (In the formula, R 1 represents a linear, branched or cyclic hydrocarbon group having 1 to 24 carbon atoms which may have a substituent, AO represents a linear or branched oxyalkylene group having 2 to 4 carbon atoms, and n represents the number of moles of the oxyalkylene group added and is a number from 1 to 30.

[0024] In formula (I), R 1 is preferably an alkyl group having 1 to 8 carbon atoms, and more preferably an alkyl group having 2 to 6 carbon atoms. Preferably, AO is an oxyethylene group. n is preferably an integer of 2-20, and more preferably an integer of 3-10. Examples of the glycol ether compound represented by general formula (I) include (poly)ethylene glycol methyl ether, (poly)ethylene glycol ethyl ether, (poly)ethylene glycol propyl ether, (poly)ethylene glycol butyl ether, (poly)ethylene glycol hexyl ether, and (poly)ethylene glycol octyl ether.

[0025] When a glycol ether compound is used as a foaming auxiliary, it may be, for example, 0.1 parts by mass or more, 0.3 parts by mass or more, 0.5 parts by mass or more, 1.0 parts by mass or more, or 1.5 parts by mass or more, or 10 parts by mass or less, 7.0 parts by mass or less, 5.0 parts by mass or less, 3.0 parts by mass or less, 2.0 parts by mass or less, or 1.0 parts by mass or less, relative to 100 parts by mass of asphalt. The glycol ether compound may be, for example, 0.1 parts by mass or more and 10 parts by mass or less, 0.3 parts by mass or more and 7.0 parts by mass or less, or 0.5 parts by mass or more and 5.0 parts by mass or less, relative to 100 parts by mass of asphalt.

[0026] Examples of the surfactant compound include cationic surfactants, amphoteric surfactants, and nonionic surfactants. Polyoxyalkylene alkyl ethers and polyoxyalkylene alkylates, which are nonionic surfactants, are preferred.

[0027] Examples of inorganic compounds include sodium hydrogen carbonate, fluorosulfonic acid, sodium sulfide, hexafluorosilicic acid, ammonium iodide, magnesium hydroxide, potassium fluoride, potassium cyanate, zinc sulfate, calcium oxide, potassium permanganate, ammonium perchlorate, hydrobromic acid, aluminum bromide, and silicon carbide.

[0028] The foaming auxiliary may be used alone or in combination of two or more kinds. The amount of the foaming auxiliary added is preferably 0.1 to 10.0 parts by mass, and more preferably 0.5 to 1.0 parts by mass, relative to 100 parts by mass of asphalt. The amount of the foaming auxiliary added may be, for example, 0.1 parts by mass or more, 0.3 parts by mass or more, 0.5 parts by mass or more, 1.0 parts by mass or more, or 1.5 parts by mass or more, relative to 100 parts by mass of asphalt, and may be 10 parts by mass or less, 7.0 parts by mass or less, 5.0 parts by mass or less, 3.0 parts by mass or less, 2.0 parts by mass or less, or 1.0 parts by mass or less. When the amount of the foaming auxiliary added is equal to or more than the lower limit of the above range, a sufficient effect of the addition is likely to be obtained, and when the amount is equal to or less than the upper limit, a sufficient effect is likely to be obtained.

[0029] In this embodiment, the amount of water added to the heated asphalt is preferably 1.0 to 10.0 parts by mass, more preferably 2.0 to 4.0 parts by mass, of the total amount of the foaming aid and water per 100 parts by mass of asphalt.

[0030] The aggregate used in this embodiment includes those generally used in paving, such as crushed stone, slag, sand, and recycled asphalt concrete aggregate (hereinafter referred to as recycled aggregate). Recycled aggregate is obtained by crushing waste asphalt mixture applied to the surface and base layers of asphalt pavement.

[0031] Generally, in asphalt mixtures containing foamed asphalt, the degree of compaction tends to decrease when the blending ratio of recycled aggregate is high, but by applying the present invention, such a decrease in the degree of compaction can be suppressed. The fatty acid compound can also restore the properties of old asphalt contained in the recycled aggregate, so an embodiment using recycled aggregate is also useful. When the aggregate contains recycled aggregate, the upper limit of the proportion of recycled aggregate relative to the total mass of the aggregate and filler may be 90 mass% or less, 80 mass% or less, 60 mass% or less, 40 mass% or less, or 30 mass% or less, or may be 5 mass% or more, 10 mass% or more, 20 mass% or more, 30 mass% or more, or 50 mass% or more, in order to ensure the degree of compaction.

[0032] The content of asphalt contained in the recycled aggregate (hereinafter referred to as old asphalt) is preferably 2.5% by mass or more based on the total mass of the recycled aggregate. The penetration index (unit: 1 / 10 mm) of the old asphalt is preferably 1 or more and less than 100. The softening point of the old asphalt is preferably 10 to 100°C. Here, the content of old asphalt is the content measured by G028 "Asphalt Extraction Test Method" in the Pavement Inspection and Testing Handbook, the penetration of old asphalt is the penetration measured by A041 "Penetration Test Method" in the Pavement Inspection and Testing Handbook, and the softening point of old asphalt is the softening temperature measured by A042 "Softening Point Test".

[0033] When the aggregate contains recycled aggregate, a regeneration additive may be used, and the above-mentioned fatty acid compound can function as the regeneration additive. The regeneration additive is an additive that has the effect of restoring the properties of old asphalt, such as flexibility. When a regeneration additive other than a fatty acid compound is used, a known regeneration additive can be used. For example, a petroleum lubricant-based regeneration additive containing a saturated content, an aromatic content, and a resin content can be mentioned. Examples of commercially available regeneration additives include RDEX (product name of ENEOS), RJ-1 (product name of Santoku Aslead), and RJ-T (product name of Takenaka Sangyo). The amount of the recycling additive added is preferably 0.1 mass % or more based on the total mass of the recycled aggregate. The rejuvenating additive is preferably added by spraying into the base mixture.

[0034] A filler may be further mixed when the foamed asphalt and aggregate are mixed in the mixer 40. Examples of the filler include stone powder, hydrated lime, cement, recycled dust, and fly ash.

[0035] The amount of foamed asphalt mixed is preferably 0.1 to 10.0 parts by mass, more preferably 1.0 to 7.0 parts by mass, per 100 parts by mass of the total of the aggregate and filler.

[0036] Other additives may be added when the foamed asphalt and the aggregate are mixed in the mixer 40. Examples of the other additives include a workability improving agent. When other additives are blended, the total mass of the other additives is preferably 0.01 to 2.00 parts by mass, and more preferably 0.05 to 0.30 parts by mass, per 100 parts by mass of the total of the added aggregate and filler.

[0037] The base mixture thus obtained contains foamed asphalt and aggregate, and may further contain fillers and other additives. The foamed asphalt may contain a foaming aid. In the foamed asphalt, bubbles are present which are formed when water vaporizes and expands.

[0038] The asphalt mixture thus obtained is used in an asphalt paving method or construction method in which it is spread and compacted. For example, an asphalt mixture can be spread on a construction base using an asphalt finisher or the like, and then compacted using a roller or the like to obtain a pavement. The compaction temperature is preferably 60 to 180° C. The degree of compaction at the compaction temperature is preferably 90% or more, more preferably 96% or more. EXAMPLES

[0039] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. In the following, the unit of content "%" is "mass %" unless otherwise specified.

[0040] The following raw materials were used: Asphalt 80 / 100: Straight asphalt 80 / 100. Aqueous solution of compound (I) (foaming auxiliary) (1): Nippon Nyukazai Co., Ltd. product name: Workfine W, glycol ether compound. Surfactant (1): Nippon Nyukazai Co., Ltd. Product name: Newcoal Recycled aggregate: old asphalt content 5.26 (mass%), penetration 20 (1 / 10 mm), softening point 66.8°C. Regeneration additive: saturates 82.9 mass%, aromatics 13.1 mass%, resins 3.3 mass%, asphaltene 0.0 mass%.

[0041] (Examples 1 to 4: Preparation of foamed asphalt) At room temperature, 2 parts by mass of the additive solution having the composition shown in Table 1 was added to 100 parts by mass of asphalt (straight asphalt 80 / 100) at 160° C. to obtain foamed asphalt. As the additive liquid, in Example 1, only water was used, and in Example 2, a mixture of surfactant (1) and water was used. In Example 3, the additive liquid was a diluted solution obtained by diluting the above aqueous solution (1) (Workfine W) with water so that the content of compound (I) (foaming auxiliary, glycol ether compound) was 25 mass %. In Example 4, the additive liquid was a diluted solution obtained by diluting the above aqueous solution (1) (Workfine W) with water so that the content of compound (I) (foaming auxiliary) was 50 mass %.

[0042] In Examples 1 to 4, the foamed asphalt was sprayed into a 20-liter aluminum container, and the volume was measured by measuring the drop from the top of the container to obtain the foaming ratio. The number of tests was 3, and the average value was calculated. The expansion ratio was measured 30 minutes, 60 minutes, and 120 minutes after adding water, and the results are shown in Figure 2.

[0043] 2, in all of Examples 1 to 4, the foaming ratio tends to decrease with time, but Examples 3 and 4, in which water and Compound (I) (foaming auxiliary) were added, had a higher foaming ratio and more bubbles remained after 120 minutes than Example 1, in which only water was added, or Example 2, in which water and a surfactant were added. In other words, the foaming duration (bubble life) was improved, and the foaming time was extended. In addition, Example 2, in which water and a surfactant were added, had a higher foaming ratio and more bubbles remained after 120 minutes than Example 1, in which only water was added. In addition, an example was also investigated in which a commercially available anionic surfactant that is also used as a dishwashing detergent was used instead of the surfactant (1) (product name Newcol, a nonionic surfactant, manufactured by Nippon Nyukazai Co., Ltd.), and the results were almost the same as those of Example 2.

[0044] [Table 1]

[0045] (Reference Examples 1 to 3: Manufacturing of standard products) A reference dense-graded asphalt mixture (basic mixture) was prepared by mixing the raw materials according to the ratio shown in Table 2. The amount of asphalt (straight asphalt 80 / 100) and regenerator additive added was adjusted so that the penetration (25°C) was 70 (unit: 1 / 10 mm). The mixing temperature was 160°C (optimum mixing temperature). Marshall specimens were prepared from the obtained reference base mixture, and the density was measured. The compaction temperature was 140°C (optimum compaction temperature), and the number of compactions was 50. Three specimens were tested, and the average value was calculated.

[0046] [Table 2]

[0047] (Examples 5 to 7) As shown in Table 3, in Reference Example 1, the mixing temperature was changed to 130°C, and the compaction temperature was changed to 110°C. In Example 5, straight asphalt 80 / 100 was used as the asphalt. In Example 6, the foamed asphalt F1 prepared in Example 1 (containing no foaming aid) was used. In Example 7, the foamed asphalt F3 prepared in Example 3 (concentration of foaming aid in additive liquid: 25%) was used. Other than that, Marshall specimens were prepared in the same manner as in Reference Example 1, and their densities were measured. The degree of compaction (unit: %) was calculated by expressing the density of each example as a percentage relative to the density (standard density) of Reference Example 1. The results are shown in FIG.

[0048] (Examples 8 to 10) As shown in Table 3, in Reference Example 2, the mixing temperature was changed to 130°C, and the compaction temperature was changed to 110°C. In Example 8, straight asphalt 80 / 100 was used as the asphalt. In Example 9, the foamed asphalt F1 prepared in Example 1 was used. In Example 10, foamed asphalt F3 prepared in Example 3 was used. Other than that, Marshall specimens were prepared in the same manner as in Reference Example 2, and their densities were measured. The degree of compaction (unit: %) was calculated by expressing the density of each example as a percentage relative to the density (standard density) of Reference Example 2. The results are shown in FIG.

[0049] (Examples 11 to 13) As shown in Table 3, in Reference Example 3, the mixing temperature was changed to 130°C, and the compaction temperature was changed to 110°C. In Example 11, straight asphalt 80 / 100 was used as the asphalt. In Example 12, the foamed asphalt F1 prepared in Example 1 was used. In Example 13, foamed asphalt F3 prepared in Example 3 was used. Other than that, Marshall specimens were prepared in the same manner as in Reference Example 3, and their densities were measured. The degree of compaction (unit: %) was calculated by expressing the density of each example as a percentage relative to the density (standard density) of Reference Example 3. The results are shown in FIG.

[0050] [Table 3]

[0051] As shown in the results in Figure 3, Examples 7, 10, and 13, which used foamed asphalt containing a foaming auxiliary, had improved compaction levels compared to Examples 5, 8, and 11, which used non-foamed straight asphalt, and Examples 6, 9, and 12, which used foamed asphalt without a foaming auxiliary.

[0052] (Examples 14 and 15) The asphalt mixtures of Examples 14 and 15 were obtained by adding 0.05 parts by mass of lubricant 1 made of a fatty acid compound shown in Table 4 below to 100 parts by mass of the base mixtures of Reference Examples 1 and 2 and mixing them. [Table 4]

[0053] A number of craftsmen were asked to carry out raking work on the base mixtures of Reference Examples 1 and 2, and the asphalt mixtures of Examples 14 and 15. All of the craftsmen commented that the raking work on the asphalt mixtures of Examples 14 and 15 was easier than that on the base mixtures of Reference Examples 1 and 2. In addition, the evaluation of the degree of compaction showed that the asphalt mixtures of Examples 14 and 15 gave better results than the base mixtures of Reference Examples 1 and 2. This was also the case when Lubricant 1 was changed to Lubricants 2 to 7. [Explanation of symbols]

[0054] 10 Asphalt measuring tank 11 Asphalt supply pipe 13 Asphalt pump 14, 24 Flow meter 20 Mixing section 21 Addition supply pipe 23 Additive pump 30 Foaming section 35 Spray nozzle 40 Mixer

Claims

1. A method for producing an asphalt mixture, comprising the steps of adding water to heated asphalt to prepare foamed asphalt, and mixing the foamed asphalt with aggregate and a fatty acid compound, wherein a foaming auxiliary which is a glycol ether compound is added in the step of preparing the foamed asphalt.

2. The method for producing an asphalt mixture according to claim 1, wherein the fatty acid compound is a compound represented by the following formula (II): R １１ -COO-(AO)m-R １２ ・・・・(II) (In the formula, R １１ is a linear, branched or cyclic hydrocarbon group having 1 to 24 carbon atoms which may have a substituent; R １２ represents a hydrogen atom or a methyl group, AO represents a linear or branched oxyalkylene group having 2 to 4 carbon atoms, and m represents the number of moles of the oxyalkylene group added, which is 0 or a number from 1 to 30.

3. The method for producing an asphalt mixture according to claim 1 , wherein the aggregate comprises recycled aggregate.

4. The method for producing an asphalt mixture according to claim 1, wherein the step of mixing the aggregate and the fatty acid compound includes mixing the foamed asphalt and the aggregate to obtain a base mixture, and then mixing the fatty acid compound with the base mixture.

Images