Method for manufacturing asphalt mixture

Abstract

To provide a method for manufacturing an asphalt mixture that can reuse construction by-products and helps reduce CO2 emissions by fixing CO2.SOLUTION: A method for manufacturing an asphalt mixture of the present invention comprises a mixing step for mixing heated aggregate in a mixer, and an asphalt spraying step for supplying asphalt into the mixer, in the mixing step, construction by-products which have water content of 1% or more and properties of fixing carbon dioxide and in which carbon dioxide are already fixed are introduced into the mixer and are mixed with heated aggregate in the mixer, and in the asphalt spraying step, asphalt is supplied when construction by-products which have the property of fixing carbon dioxide and in which carbon dioxide is already fixed are introduced, and the time shorter than that required for all moisture contained in the construction by-products to evaporate has elapsed, and the method comprises a step for mixing the heated aggregate and asphalt in the mixer after the asphalt spraying step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Construction by-products are all items obtained as a by-product of construction work, and include construction soil, concrete blocks, asphalt and concrete blocks, construction wood, construction sludge, waste paper, scrap metal, glass and concrete waste (excluding that generated by the construction, renovation, or removal of structures), and ceramic waste, all of which are removed from the construction site, as well as mixed construction waste, which is a mixture of these.Conventional technologies for effectively utilizing such construction by-products include adding fly ash, which is ash produced when burning coal, sewage sludge incineration ash, gypsum, waste tires, scallop shells, etc. to asphalt mixtures. In recent years, there has been a great demand for reducing carbon dioxide (CO2) emissions, and technology for fixing CO2 has been attracting attention. However, technology to reuse construction by-products and fix CO2 has not yet been developed.

[0003] As another prior art, a method for producing carbon dioxide-fixed concrete has been proposed (see Patent Document 1), but there is no disclosure about fixing CO2 in an asphalt mixture. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-96668 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention was proposed in consideration of the problems of the prior art described above, and aims to provide a method for manufacturing asphalt mixtures that can reuse construction by-products and fix CO2 (carbon dioxide), thereby helping to reduce CO2 emissions. [Means for solving the problem]

[0006] The method for producing an asphalt mixture of the present invention is as follows: a mixing step of mixing the heated aggregate (and stone powder) using a mixer (1); The method includes an asphalt spraying step of supplying asphalt into a mixer (1), In the mixing step, a construction by-product (CO2 fixation material) having a water content of 1% or more and having the property of fixing CO2, in which CO2 has already been fixed, is introduced into a mixer (1) and mixed with heated aggregate (and stone powder) in the mixer (1), In the asphalt spraying process, a construction by-product (CO2 fixation material) that has the property of fixing CO2 and in which CO2 has already been fixed is introduced, and then asphalt is supplied when a time (predetermined mixing time T: predetermined mixing time) that is shorter than the time it takes for all the moisture contained in the construction by-product to evaporate has elapsed. This method is characterized by having a step in which heated aggregate (and stone powder) and asphalt are mixed in a mixer (1) after the asphalt spraying step.

[0007] In the present invention, it is preferable to have a step of determining the time (T) for moisture to remain in the construction by-product before carrying out the mixing step and the asphalt spraying step so that the asphalt supplied in the asphalt spraying step can obtain a foamed effect.

[0008] The manufacturing apparatus (20) for carrying out the asphalt mixture manufacturing method of the present invention comprises: a mixer (1) for mixing the contents; an aggregate feeding device (2) that heats aggregate and supplies it to the mixer (1); a construction by-product feeding device (3: CO2 fixation material feeding device) that supplies construction by-products (CO2 fixation material) having a water content of 1% or more and having the property of fixing CO2, in which CO2 has already been fixed, to the mixer (1); an asphalt spraying device (4) that supplies (sprays) asphalt into the mixer (1); The system includes a control device (10) that controls the timing of supplying aggregate from the aggregate charging device (2) into the mixer (1), the timing of supplying construction by-products from the construction by-product charging device (3) into the mixer (1), and the timing of supplying (spraying) asphalt from the asphalt spraying device (4) into the mixer (1), The control device (10) is characterized by having a function of controlling the supply (spraying) of asphalt from the asphalt spraying device (4) into the mixer (1) when a time (T: preset mixing time: specified mixing time) shorter than the time it takes for all the moisture contained in the construction by-product (CO2 fixation material), which has the property of fixing CO2 and in which CO2 has already been fixed, has elapsed after the construction by-product (CO2 fixation material) that has the property of fixing CO2 has been supplied from the construction by-product feeding device (3) into the mixer (1).

[0009] In the present invention, the time (T) from when a construction by-product (CO2 fixation material) that has the property of fixing CO2 and in which CO2 has already been fixed is added until when asphalt is sprayed is preferably a time during which moisture remains in the construction by-product so that the asphalt can obtain a foamed effect due to the moisture remaining in the construction by-product. Here, the time (T) is, for example, 5 to 30 seconds, and varies depending on the amount of stone powder (filler), the water content of the CO2 fixation material, the mixing time, and other factors.

[0010] In the present invention, the water content of the construction by-product (CO2 fixation material) is preferably 1% to 30%. [Effects of the Invention]

[0011] According to the present invention having the above-mentioned configuration, when components other than asphalt are mixed, a construction by-product (CO2 fixation material) that has the property of fixing CO2 and in which CO2 has already been fixed is introduced into the mixer 1. Therefore, the asphalt mixture produced by the present invention contains the CO2 fixation material. By incorporating the CO2 fixation material into the asphalt mixture (making it a composition), the CO2 fixed in the CO2 fixation material is fixed in the road pavement as the asphalt mixture without diffusing into the atmosphere. As a result, CO2 emissions are reduced by the amount of CO2 fixed in the asphalt mixture that forms the road pavement.

[0012] In the illustrated embodiment, the CO2 fixation material is not dried, but is directly charged into the mixer 1 in a state of high moisture content. Therefore, there is no need to dry the CO2 fixation material with a high moisture content using a burner or the like, and CO2 is prevented from being emitted when the CO2 fixation material is dried using a burner or the like. Furthermore, after the CO2 fixation material with a high water content is charged into the mixer (1), it is mixed in the mixer (1) for a specified mixing time (T), heated by (the heat contained in) the aggregate heated by a burner or dryer, and the asphalt is sprayed after a specified time (pre-set mixing time T) has passed. Therefore, if the CO2 fixation material immediately after being charged into the mixer (1) contains a large amount of water (water with a water content not exceeding 30%), this large amount of water will disappear during the specified mixing time (T), preventing problems caused by the asphalt mixture containing excessive water. It was found that if the moisture content exceeds 30%, when the CO2 fixation material is mixed with other materials and heated by heated aggregate, moisture remains in the asphalt mixture, reducing the performance of the resulting asphalt mixture.

[0013] According to the inventor's experiments, when a high-moisture CO2 fixation material is put into a mixer and mixed with heated aggregate for a specified mixing time (T), a small amount of moisture remains in the high-moisture CO2 fixation material. The asphalt that is added (sprayed) after dry mixing achieves a foamed effect (effects of foamed asphalt, such as improved compaction). Furthermore, residual stability is not reduced, and water resistance is also ensured. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a flowchart showing the steps of a manufacturing method according to an embodiment of the present invention. [Figure 2] 1 is a block diagram of a manufacturing apparatus used in a method for manufacturing an asphalt mixture according to an embodiment of the present invention. [Figure 3] FIG. 2 is a functional block diagram of a control unit of a manufacturing apparatus used in a manufacturing method according to an embodiment of the present invention. [Figure 4] FIG. 2 is a graph showing the moisture content-density characteristics of the asphalt mixture in the experimental example. [Figure 5] FIG. 1 is a graph showing the moisture content-residual stability characteristics of asphalt mixtures in experimental examples. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In Tables 1, 2, Figures 4 and 5, the term "light calcium carbonate" refers to a "construction by-product with the property of fixing CO2" (CO2 fixation material), and includes, for example, a commercially available product containing a construction by-product whose main component is calcium carbonate (for example, the product name "Eco Tankal (registered trademark)" sold by Nippon Concrete Industries Co., Ltd.). In the following explanation, "construction by-products with the property of fixing CO2" may be referred to as "CO2 fixation materials."

[0016] First, referring to FIG. 1, an embodiment of the method for producing an asphalt mixture of the present invention will be described. In Figure 1, in step S1, aggregates and other materials that make up the asphalt mixture are charged into mixer 1 (Figure 2) and mixed (dry mixing). In other words, materials other than asphalt and the CO2 fixation material are charged into mixer 1 in step S1. At this time, aggregates are charged into mixer 1 in the same manner as in conventional technology. When replacing a portion of the stone powder with a construction by-product that has the property of fixing CO2 and that has already fixed CO2 (CO2 fixation material) ("50% replacement" described below), in step S1, the stone powder is fed from the stone powder supply device 8 through the supply line SPL8 and the stone powder feeder 9 installed therein into the mixer 1. When replacing all of the stone powder with CO2 fixation material (for example, "100% replacement" described below), only the heated aggregate is fed into the mixer 1 in step S1. Although not shown in the figure, in the prior art, aggregate is filled into a cold bin (container) and transported by a belt conveyor to a dryer or burner where it is heated. The dust of the heated aggregate is filtered by an explosive filter and fed to a mixer, and the heated aggregate other than the dust is transported by an elevator to a screen where it is sieved, stored according to particle size in a container with heat retention (hot bin), and then fed into the mixer. The composition of the asphalt mixture other than asphalt is as shown in Table 1 below. Table 1 TIFF2025163347000002.tif61164

[0017] In the illustrated embodiment, part or all of the stone powder is replaced with a construction by-product that has the property of fixing CO2 and that has already fixed CO2 (CO2 fixing material). In the illustrated embodiment, the case where 50% of the stone powder is replaced with the CO2 fixation material is described as "50% replacement," and the case where the entire amount of stone powder is replaced with the CO2 fixation material is described as "100% replacement."

[0018] In step S2, a CO2 fixation material (calcium carbonate) with a high moisture content is introduced into the mixer 1. Although not explicitly shown in Figure 1, steps S1 and S2 can be performed simultaneously. That is, the heated aggregate, materials other than aggregate (stone powder), and CO2 immobilization material can be supplied to the mixer and mixed at the same time. Of course, the heated aggregate, stone powder, and CO2 immobilization material can also be supplied to the mixer at different times and mixed.

[0019] The amount of the CO2 fixation material added is set in the range of 0.5% to 35% by weight of the asphalt mixture. According to experiments conducted separately by the inventors, it was found that when the amount of CO2 fixation material added is less than 0.5% by weight of the asphalt mixture, the amount of CO2 fixed in the asphalt mixture is extremely small and does not contribute to reducing CO2 emissions. On the other hand, it was found that if the amount of CO2 fixation material added exceeds 35% by weight of the asphalt mixture, the performance required for the asphalt mixture will not be met.

[0020] The moisture content of the CO2 fixation material ranges from 1% to 30%. According to experiments conducted by the inventors, if the moisture content is less than 1%, the moisture is completely removed from the CO2 fixation material when it is put into a mixer and mixed with heated aggregate, resulting in a small foaming effect of the asphalt. On the other hand, when the moisture content exceeds 30%, if the CO2 fixation material is mixed with other materials and heated by heated aggregate, moisture remains in the asphalt mixture, and the performance of the resulting asphalt mixture is reduced.

[0021] In step S3, the CO2 fixation material is charged into the mixer 1 and then mixed for a preset time T (mixing time in dry mixing). By mixing with the heated aggregate in the mixer 1, the water contained in the CO2 fixation material with a high water content evaporates. In order for the manufactured asphalt to exhibit its foamed effect, an appropriate amount of water must remain in the CO2 fixation material (calcium carbonate). Therefore, a mixing time T (predetermined mixing time: mixing time in dry mixing) is set in advance so that an appropriate amount of water remains. The preset time T is a time shorter than the time it takes for all the water contained in the CO2 fixation material with a high water content to evaporate, for example, 5 to 30 seconds. In the illustrated embodiment, the water content of the CO2 fixation material is 1% to 30%. This predetermined mixing time T is determined in advance by experiments or the like before carrying out the manufacturing method according to the illustrated embodiment. The predetermined mixing time T varies depending on factors such as the amount of stone powder (filler), the water content of the CO2 immobilization material, the mixing time of materials other than the CO2 immobilization material (aggregate, stone powder), and other factors. Steps S1 to S3 in the method for producing an asphalt mixture according to the embodiment shown in the drawings constitute a mixing step in which heated aggregate (or stone powder) and a CO2 fixation material are mixed by a mixer 1.

[0022] After a predetermined mixing time T has elapsed in step S3, asphalt is sprayed into the mixer 1 (asphalt is supplied into the mixer) in step S4. In step S5 following step S4, after the asphalt is supplied, it is further mixed in the mixer 1 (wet mixing). This mixing is carried out for a predetermined time TA (predetermined asphalt mixing time: predetermined mixing time in wet mixing). Then, an asphalt mixture is produced. The predetermined asphalt mixing time TA is also determined in advance by testing or the like before production as the time required to produce an asphalt mixture that is properly mixed and exhibits a proper foaming effect. When the mixing time in step S5 is over, the foamed asphalt mixture is completed. According to the asphalt mixture manufacturing method shown in Figure 1, the high-moisture CO2 fixation material is not dried, but is directly charged into the mixer 1 in its high-moisture state. This eliminates the need to completely dry the high-moisture CO2 fixation material using a burner or dryer, and reduces CO2 emissions by at least the amount of CO2 that would be emitted if the CO2 fixation material were dried using a burner or dryer. Furthermore, after the high-water content CO2 fixation material is charged into mixer 1, it is mixed in mixer 1 and heated (by heated aggregate), and after the specified mixing time T (specified dry mixing time) has elapsed, asphalt is sprayed on. Therefore, even if the high-water content CO2 fixation material contains excessive moisture, with a moisture content of more than 30%, this excess moisture evaporates during the specified mixing time T, so the produced asphalt mixture does not contain excessive moisture, residual stability is not reduced, and water resistance is ensured.

[0023] According to experiments conducted by the inventors, a CO2 fixation material with a high water content is placed in a mixer and dry mixed for a specified mixing time T, resulting in a small amount of residual moisture in the dry-mixed CO2 fixation material. This allows the asphalt mixture sprayed with asphalt to achieve a foamed effect. Therefore, the resulting asphalt mixture exhibits the same effect as a foamed asphalt mixture, improving compaction. However, even if a small amount of moisture remains in the CO2 fixation material, no significant decrease in the residual stability (a parameter used to evaluate water resistance) of the resulting asphalt mixture was observed.

[0024] Next, a manufacturing facility for carrying out the manufacturing method of FIG. 1 will be described with reference to FIG. In Figure 2, the asphalt mixture manufacturing apparatus 20 according to the illustrated embodiment includes a mixer 1 that mixes the contents, an aggregate feeding device 2 that supplies aggregate to the mixer 1, a CO2 immobilization material feeding device 3 (construction by-product feeding device) that supplies CO2 immobilization material to the mixer 1, an asphalt spraying device 4 that sprays asphalt into the mixer 1, a stone powder feeding device 9 that supplies stone powder to the mixer 1, and a control device 10 (concrete unit). Although not shown in FIG. 2, the aggregate is heated by a heating device (dryer or burner) not shown, and the heated aggregate is introduced into the mixer 1. The CO2 fixation material is sent from a CO2 fixation material supply source 6 via a supply line SPL3 to a CO2 fixation material supply device 3, and is supplied from the CO2 fixation material supply device 3 to the mixer 1 via a supply line SPL4. Stone powder is supplied to the mixer 1 from a stone powder supply device 8 via a supply line SPL8 and a stone powder injection device 9 installed therein. However, when all the stone powder is replaced with CO2 fixation material (100% replacement), the stone powder is not supplied to the mixer 1. When only "100% replacement" (all replacement with CO2 fixation material) is performed, the stone powder supply device 8, stone powder injection device 9, and supply line SPL8 can be omitted. In Figure 1, aggregate heated by a heating device (not shown), stone powder, and CO2 fixation material may be simultaneously supplied and mixed into mixer 1. It is also possible to supply heated aggregate, stone powder, and CO2 fixation material into the mixer at different times and mix them. Asphalt is sent from an asphalt supply source 7 via a supply line SPL5 to the asphalt sprayer 4, and is sprayed from the asphalt sprayer 4 into the mixer 1 via a supply line SPL6.

[0025] The control device 10 has the function of controlling the timing of supplying aggregate from the aggregate supply device 2 into the mixer 1 and the timing of supplying CO2 fixation material from the CO2 fixation material supply device 3 into the mixer 1. When only a portion of the stone powder is replaced with CO2 fixation material, such as in the case of "50% replacement," the control device 10 also controls the timing of supplying stone powder into the mixer 1. However, in the case of "100% replacement," the control device 10 controls the stone powder supply device 9 not to supply stone powder to the mixer 1. The control device 10 also has a function of controlling the timing at which asphalt is sprayed from the asphalt spraying device 4 into the mixer 1. Although this overlaps with what was explained in Figure 1, controlling the timing at which asphalt is sprayed from the asphalt sprayer 4 into the mixer 1 includes controlling the asphalt sprayer 4 to spray (supply) asphalt into the mixer 1 after the CO2 fixation material has been supplied into the mixer 1, a time that is shorter than the time it takes for all the moisture contained in the CO2 fixation material to evaporate, i.e., a preset mixing time T (a predetermined mixing time in dry mixing), has elapsed, and mixing the asphalt in the mixer 1 for a preset time TA (a predetermined asphalt mixing time in wet mixing) after the asphalt has been supplied. For such control, the control device 10 is connected to the CO2 fixation material feeding device 3 by a signal transmission line SL1 (mutual directional signal line), to the asphalt spraying device 4 by a signal transmission line SL2 (mutual directional signal line), to the aggregate feeding device 2 by a signal transmission line SL3 (mutual directional signal line), to the stone powder feeding device 9 by a signal transmission line SL7 (mutual directional signal line), and to the mixer 1 by a signal transmission line SL4 (mutual directional signal line).

[0026] Referring to FIG. 3, various functional blocks in the control device 10 are shown. In FIG. 3, the control device 10 has a timing means 10A, a control signal transmission block 10B, and a memory block 10C. The timing means 10A receives information that the supply of CO2 fixation material from the CO2 fixation material feeding device 3 to the mixer 1 has been started (started) via the signal transmission line SL1 (including the interface I / F), and also measures the elapsed time (dry mixing mixing time) since the start of the supply (feed) of the CO2 fixation material to the mixer 1, and transmits this (the elapsed time since the start of the supply of the CO2 fixation material) to the control signal transmission block 10B via the signal transmission line SL5. The timing means 10A also has the function of acquiring information that the asphalt spraying device 4 has started spraying asphalt into the mixer 1 via the signal transmission line SL2-1 (including the interface I / F), measuring the elapsed time since the asphalt spraying started (wet mixing time) and transmitting this information (the elapsed time since the asphalt spraying started) to the control signal transmission block 10B via the signal transmission line SL5.

[0027] The control signal transmission block 10B has the function of obtaining the elapsed time after the start of supply of the CO2 fixation material from the timing means 10A, and when that elapsed time (mixing time after supply of the CO2 fixation material (mixing time in dry mixing)) reaches the predetermined CO2 fixation material mixing time T (a predetermined time shorter than the time required for all the water contained in the CO2 fixation material to evaporate: the predetermined mixing time in dry mixing) obtained from the memory block 10C via the signal transmission line SL6, transmitting a control signal to start spraying asphalt to the asphalt spraying device 4 via the signal transmission line 2-2 (including the interface I / F). The control signal transmission block 10B also has the function of acquiring the elapsed time (timing result) after the start of asphalt spraying from the timing means 10A, and when that elapsed time (wet mixing time) reaches the specified asphalt mixing time TA (appropriate time for mixing after asphalt spraying: specified mixing time in wet mixing) acquired from the memory block 10C via the signal transmission line SL6, transmitting a control signal for ending mixing to the mixer 1 via the signal transmission line SL4 (including the interface I / F). Furthermore, when replacing a portion of the stone powder with CO2 fixation material (for example, "50% replacement"), the control signal transmission block 10B transmits a control signal to start stone powder supply and a control signal to end stone powder supply to the stone powder feeding device 9. When replacing all of the stone powder with CO2 fixation material (100% replacement), the control signal transmission block 10B transmits a control signal to the stone powder feeding device 9 not to supply stone powder to the mixer 1.

[0028] The memory block 10C stores information and data necessary to control the production of the asphalt mixture, such as the predetermined CO2 fixation material mixing time T (predetermined mixing time in dry mixing) and the predetermined asphalt mixing time TA (predetermined mixing time in wet mixing), and is used by each control block as needed. As described above, the mixing times T and TA are determined at a stage prior to the production of the asphalt mixture and stored in the memory block 10C. The control device 10 controls the start and end of operation of the aggregate feeding device 2, the CO2 fixation material feeding device 3, the stone powder feeding device 9, and the mixer 1, respectively.

[0029] Next, an experiment on the asphalt mixture produced in the above-described embodiment will be described. [Experimental Example 1] Experimental Examples 1 and 2 were carried out using a dense-graded asphalt mixture. The composition of the dense-graded asphalt mixture, other than the asphalt, is shown in Table 1. Regarding the dense-graded asphalt mixture (the composition other than asphalt is shown in Table 1), the density (g / cm) was measured for test materials in which 50% of the filler (stone powder) was replaced with the CO2 fixation material (50% replacement) and test materials in which 100% of the filler was replaced with the CO2 fixation material (100% replacement) when the water content (%) was set to 0%, 10%, and 20%. 3 For test materials in which the filler was replaced with CO2 fixation material (100% replacement), the density was also measured when the moisture content was set to 30%. The measurement results are shown in the moisture content-density characteristic diagram in Figure 4. As is clear from Figure 4, the higher the moisture content, the easier it was to compact and the higher the density. In other words, the higher the moisture content, the better the degree of compaction. It is presumed that the higher the moisture content, the more the foamed effect was exerted.

[0030] [Experimental Example 2] As in Experimental Example 1, for dense-graded asphalt mixtures whose compositions other than asphalt are shown in Table 1, the residual stability (%) was measured when the moisture content was 0%, 10%, and 20% for test materials in which 50% of the filler was replaced with CO2 fixation material (50% replacement) and test materials in which the filler was replaced with CO2 fixation material (100% replacement).For the 100% replacement, the residual stability was also measured when the moisture content was 30%. Here, the residual stability is a parameter that serves as an index for evaluating the water resistance of an asphalt mixture. The measurement results are shown in the moisture content-residual stability characteristic diagram in Figure 5. As is clear from FIG. 5, even when the moisture content increased, the residual stability did not decrease, and the water resistance of the asphalt mixture according to the experimental example did not decrease.

[0031] Although Experimental Examples 1 and 2 were conducted on dense-graded asphalt mixtures, the illustrated embodiments can be applied to porous asphalt mixtures. When the illustrated embodiment is applied to a porous asphalt mixture, the composition other than asphalt is shown in Table 2 below. Table 2 TIFF2025163347000003.tif68167

[0032] It should be noted that the illustrated embodiments are merely examples and are not intended to limit the technical scope of the present invention. [Explanation of symbols]

[0033] 1. Mixer 2...Aggregate feeding device 3. CO2 fixation material input device (construction by-product input device) 4. Asphalt spraying equipment 9...Stone powder feeding device 10. Control unit (control device) 20. Asphalt mixture manufacturing equipment T: The specified mixing time (after adding the CO2 fixation material to the mixer) TA: Specified asphalt mixing time

Claims

1. a mixing step of mixing the heated aggregate with a mixer; An asphalt spraying step of supplying asphalt into a mixer is included. In the mixing step, a construction by-product having a water content of 1% or more and a property of fixing carbon dioxide, in which carbon dioxide has already been fixed, is introduced into a mixer and mixed with heated aggregate in the mixer, In the asphalt spraying process, asphalt is supplied when a time has passed that is shorter than the time it takes for all of the moisture contained in the construction by-product to evaporate after a construction by-product that has the property of fixing carbon dioxide and in which carbon dioxide has already been fixed is input, A method for producing an asphalt mixture, characterized by comprising a step of mixing heated aggregate and asphalt in a mixer after the asphalt spraying step.

2. The method for producing an asphalt mixture of claim 1, wherein the time from when a construction by-product having the property of fixing carbon dioxide and in which carbon dioxide has already been fixed is added to when asphalt is sprayed is the time during which moisture remains in the construction by-product so that the asphalt supplied in the asphalt spraying process can obtain a foamed effect due to the moisture remaining in the construction by-product.

3. The method for producing an asphalt mixture according to claim 1 or 2, wherein the moisture content of the construction by-product is 1% to 30%.

4. 4. The method for manufacturing an asphalt mixture according to claim 3, further comprising a step of determining the time for which moisture remains in the construction by-products before carrying out the mixing step and the asphalt spraying step, so that the asphalt supplied in the asphalt spraying step can obtain a foamed effect due to the moisture remaining in the construction by-products.

5. a mixer for mixing the contents; an aggregate feeding device that heats aggregate and supplies it to the mixer; a construction by-product feeding device that supplies construction by-products having a water content of 1% or more and a property of fixing carbon dioxide, in which carbon dioxide has already been fixed, to a mixer; an asphalt spraying device that supplies asphalt into the mixer; a control device having a function of controlling the timing of supplying aggregate from the aggregate feeding device into the mixer, the timing of supplying construction by-products from the construction by-product feeding device into the mixer, and the timing of supplying asphalt from the asphalt spraying device into the mixer; The control device is an asphalt mixture manufacturing device characterized in that it has the function of controlling the supply of asphalt from an asphalt spraying device into the mixer when a construction by-product that has the property of fixing carbon dioxide and in which carbon dioxide has already been fixed is supplied into the mixer from a construction by-product feeding device, and a time shorter than the time it takes for all of the moisture contained in the construction by-product to evaporate has elapsed.

6. The asphalt mixture manufacturing device of claim 5, wherein the time from when construction by-products having the property of fixing carbon dioxide and in which carbon dioxide has already been fixed are introduced to when asphalt is sprayed is the time during which moisture remains in the construction by-products so that the asphalt supplied from the asphalt spraying device can obtain a foamed effect due to the moisture remaining in the construction by-products.

7. The asphalt mixture manufacturing apparatus according to any one of claims 5 and 6, wherein the moisture content of the construction by-product is 1% to 30%.

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