JP6983855B2 - Manufacturing system and method of recycled asphalt mixture - Google Patents

Description

The present invention relates to a production system and method for a recycled asphalt mixture.

In pavement such as roadways and sidewalks, a regenerated asphalt mixture obtained by kneading a regenerated aggregate, a new aggregate, a heated asphalt, and a regenerating additive is often used.

Recycled aggregate is made by dismantling, crushing and classifying existing asphalt pavement. Deteriorated and hardened asphalt (former asphalt) is attached to such recycled aggregate. In order to improve the properties of the old asphalt, it is common practice to add a regeneration additive to the recycled aggregate in the production of the recycled asphalt mixture.

FIG. 8 shows the configuration of a conventional recycled asphalt mixture manufacturing system 10. The conventional recycled asphalt mixture manufacturing system 10 includes a mixer 11.

The regenerated aggregate is housed in the measuring tank 12, the new aggregate is housed in the measuring tank 13, and the heated asphalt is housed in the measuring tank 14. The regenerated aggregate contained in the measuring tank 12 and the new aggregate housed in the measuring tank 13 are charged into the mixer 11, and the heated asphalt housed in the measuring tank 14 is pumped by the pump 15 and the nozzle 16 is used. Is discharged to the mixer 11.

The regeneration additive contained in the tank 17 is discharged to the mixer 11 in an appropriate amount at the timing of kneading the regenerated aggregate, the new aggregate and the heated asphalt. Specifically, the regeneration additive is pumped by the pump 19 via a pipe 18 connected to the tank 17 and extended to the upper side of the mixer 11, and is discharged from the tip of the pipe 18 to the mixer 11.

Therefore, a technical problem to be solved in order to surely and efficiently improve the old asphalt contained in the regenerated aggregate arises, and an object of the present invention is to solve this problem.

In order to achieve the above object, the method for producing a regenerated asphalt mixture according to the present invention is a method for producing a regenerated asphalt mixture in which a regenerated aggregate, a heated asphalt and a regenerating additive are mixed, and the regenerating additive is used. It is diffused and sprayed on the regenerated aggregate in a state of being crushed by a high-speed air stream and slightly foamed.

According to this configuration, by diffusing and spraying the slightly foamed recycling additive on the recycled aggregate, the improvement of the old asphalt contained in the recycled aggregate is promoted, and a high-quality recycled asphalt mixture can be produced. can.

Further, in the method for producing a regenerated asphalt mixture according to the present invention, it is preferable that a foaming aid is mixed with the regenerating additive.

According to this configuration, since the additive for regeneration is easily slightly foamed, the improvement of the old asphalt contained in the recycled aggregate is further promoted, and a high-quality recycled asphalt mixture can be produced.

Further, in order to achieve the above object, the recycled asphalt mixture manufacturing system according to the present invention is a recycled asphalt mixture manufacturing system, and is a mixer for kneading a recycled aggregate, a recycling additive, and a heated asphalt. When, a, a two-fluid nozzle to diffuse scatter into the mixer in a state in which said reproducing additive is finely foamed and pulverized at a high speed air stream.

According to this configuration, by diffusing and spraying the slightly foamed recycling additive on the recycled aggregate, the improvement of the old asphalt contained in the recycled aggregate is promoted, and a high-quality recycled asphalt mixture can be produced. can.

Further, in the regenerated asphalt mixture manufacturing system according to the present invention, it is preferable that the microfoaming means is a two-fluid nozzle in which the regenerating additive is pulverized with a high-speed air flow to microfoam.

Further , by using the two-fluid nozzle, it is possible to easily perform fine foaming of the regenerating additive and diffusion spraying of the regenerating additive.

Further, it is preferable that the regenerated asphalt mixture manufacturing system according to the present invention further includes a foaming device for foaming the heated asphalt.

According to this configuration, the slightly foamed regenerative additive and the foamed asphalt (foamed asphalt) improve the mixability of the regenerated asphalt mixture, and a good quality regenerated asphalt mixture can be produced. ..

INDUSTRIAL APPLICABILITY The present invention can promote the improvement of the old asphalt contained in the regenerated aggregate by diffusing and spraying the slightly foamed regenerative additive to the regenerated aggregate, and can produce a high-quality regenerated asphalt mixture.

The schematic diagram which shows the structure of the manufacturing system of the regenerated asphalt mixture which concerns on one Embodiment of this invention. The flowchart which shows an example of the procedure for producing the regenerated asphalt mixture using the system of FIG. The graph which compares the bulk density of the various examples obtained by the method of this invention and the comparative example obtained by a conventional method. The graph which compares the crushing coefficient of the various examples obtained by the method of this invention and the comparative example obtained by a conventional method. The graph which shows the influence which the presence or absence of a foaming aid has on the bulk density and the crushing coefficient. A table showing measurement conditions and measurement results of core densities and workability evaluation results of various examples obtained by the method according to the present invention and comparative examples obtained by the conventional method. The graph which compares the core density of the various examples obtained by the method of this invention and the comparative example obtained by a conventional method. The schematic diagram which shows the structure of the manufacturing system of the conventional recycled asphalt mixture.

An embodiment of the present invention will be described with reference to the drawings. In the following, when the number, numerical value, quantity, range, etc. of the components are referred to, the number is limited to the specific number unless it is explicitly stated or the principle is clearly limited to the specific number. It is not a thing, and it may be more than or less than a specific number.

In addition, when referring to the shape and positional relationship of components, etc., unless otherwise specified or when it is considered that it is not clearly the case in principle, those that are substantially similar to or similar to the shape, etc. are used. include.

In addition, the drawings may be exaggerated by enlarging the characteristic parts in order to make the features easy to understand, and the dimensional ratios and the like of the components are not always the same as the actual ones.

FIG. 1 is a schematic diagram showing a configuration of a regenerated asphalt mixture manufacturing system 1 according to an embodiment of the present invention.

The production system 1 of the regenerated asphalt mixture includes a mixer 2. Mixer 2 is a kneaded biaxial Pugmill mixer, and a regenerated asphalt mixture is produced by kneading a regenerated aggregate, a new aggregate, a heated asphalt, and a regenerating additive. The regenerated asphalt mixture is not limited to that used for the surface layer and the base layer of asphalt pavement, and includes those used for roadbed materials. Further, the mixer 2 is not limited to the kneaded biaxial Pugmill mixer, and may be, for example, a continuous drum mixer or the like.

The regenerated aggregate is housed in the first measuring tank 3. The reclaimed aggregate is a classification of the aggregate generated when the existing asphalt pavement is dismantled, and the deteriorated old asphalt adheres to the surface. The regenerated aggregate is charged into the mixer 2 from the first measuring tank 3.

The second measuring tank 4 contains a new aggregate. The new aggregates are crushed stone, sand and the like. The new aggregate is charged into the mixer 2 from the second measuring tank 4.

The third measuring tank 5 contains heated asphalt. The heated asphalt is, for example, straight asphalt having a standard according to the desired property. The heated asphalt is pumped through the pipe 52 by the first pump 51 and charged into the mixer 2 from the nozzle 53.

Further, a foaming device (not shown) may be provided between the first pump 51 and the nozzle 53. The configuration of the foaming apparatus is known, for example, water is added to the heated asphalt to foam the heated asphalt. As a result, the fine bubbles remaining in the heated asphalt exert a bearing effect, smooth the movement of the aggregate, and improve the mixing property and compaction property of the regenerated asphalt mixture.

The tank 6 contains the additive for regeneration. The additive for regeneration improves the properties of the old asphalt adhering to the regenerated aggregate. Examples of the recycling additive include asphalt-based recycling additives, petroleum lubricating oil-based recycling additives, mineral-based recycling additives, animal and vegetable oil-based recycling additives, asphalt emulsion-based recycling additives, and the like. Be done. In addition, the above-mentioned one type of additive may be used alone, or two or more types may be used in combination. The blending amount of the additive for regeneration is preferably set within the range of 1 to 40% by mass ratio with respect to the old asphalt contained in the recycled aggregate. The regeneration additive is pumped from the third tank 6 to the two-fluid nozzle 63 via the pipe 62 by the second pump 61.

Further, it is preferable that the regeneration additive in the tank 6 is mixed with a foaming aid. The foaming aid is a nonionic surfactant comprising, for example, polyethylene glycol monooleate or sorbitan trioleate, which promotes microfoaming of the regeneration additive. The blending amount of the foaming aid is preferably set within the range of 1 to 3% by mass ratio with respect to the additive for regeneration.

The two-fluid nozzle 63 crushes the liquid regeneration additive with a high-speed air flow such as compressed air, nitrogen, or steam supplied from the compressor 64 to cause fine foaming. The slightly foamed regeneration additive is discharged toward the mixer 2. By changing the shape of the discharge port of the two-fluid nozzle 63, the range in which the regeneration additive is sprayed can be adjusted.

The two-fluid nozzle 63 has, for example, a configuration in which a pipe for supplying the regeneration additive and a pipe for supplying the high-speed airflow are directly connected to the nozzle for discharging the regeneration additive, or the regeneration additive is used. It is also possible to have a configuration in which the chamber for crushing with a high-speed air flow and the nozzle for discharging the regeneration additive are separated and connected by a pipe or the like. In particular, in the latter configuration, since a chamber having a relatively large capacity as compared with the nozzle is used, the amount of gas contained in the regeneration additive can be increased.

Each device constituting the production system 1 of the recycled asphalt mixture is operated and controlled by a control device (not shown). The control device is composed of, for example, a CPU, a memory, and the like, and the functions of the control device are realized by controlling using software.

Next, the operation of the production system 1 of the regenerated asphalt mixture will be described with reference to FIG. FIG. 2 is a flowchart showing a procedure for producing a regenerated asphalt mixture. Hereinafter, a case where a regenerated asphalt mixture is produced with a mixing amount of 1000 kg per batch and a mixing time of about 60 seconds will be described as an example.

First, the regenerated aggregate contained in the first measuring tank 3 is charged into the mixer 2 (step S1). The regenerated aggregate is preheated before being charged into the mixer 2. The input amount of the regenerated aggregate is about 600 kg.

Further, the regeneration additive is diffusely sprayed from the two-fluid nozzle 63 to the mixer 2 at substantially the same time as the step S1 or following the step S1 (step S2). The amount of the additive for regeneration is about 1 to 3 kg, but is appropriately adjusted according to the amount and properties of the recycled aggregate. The spraying time of the additive for regeneration is, for example, about 5 to 10 seconds.

Next, the regenerated aggregate and the regenerating additive in the mixer 2 are kneaded (step S3). The time required for kneading is, for example, about 5 to 10 seconds.

Next, a predetermined amount of new aggregate is charged into the mixer 2 (step S4). The new aggregate is preheated before being charged into the mixer 2. The input amount of new aggregate is about 380 kg.

Next, about 25 kg of heated asphalt is charged into the mixer 2 from the nozzle 53 (step S5).

Further, kneading with the mixer 2 is performed in parallel with the step S5 (step S6). The time required for kneading is, for example, about 40 to 50 seconds counting from the start of charging the heated asphalt.

Then, the regenerated asphalt mixture obtained by kneading with the mixer 2 is discharged to the outside (step S7). The regenerated asphalt mixture discharged from the mixer 2 is kneaded into a carrier or the like.

Next, the present invention will be described based on detailed examples, but the present invention is not limited to the examples described later. Hereinafter, the test piece of the regenerated asphalt mixture obtained by the present invention (hereinafter referred to as "Examples 1 to 3") and the test piece obtained by the conventional regenerated asphalt mixture manufacturing system 10 shown in FIG. 8 (hereinafter referred to as "Examples"). , Called "comparative example").

[Sample manufacturing method]
-Example 1:
Diffusion and spraying 1 to 3 kg of the regenerative additive slightly foamed by the chamber type 2 fluid nozzle 63 on about 600 kg of the regenerated aggregate in the mixer 2 (air amount: 3700NL / min, air pressure: 0.4 MPa, orifice diameter:: φ9 mm, spray width: W130 mm x L800 mm). Then, about 380 kg of new aggregate is put into the mixer 2, and after the heated asphalt is put into the mixer 2 from the pipe 52, the mixture is kneaded with the mixer 2 to produce a regenerated asphalt mixture.

-Example 2:
Diffusion and spraying 1 to 3 kg of the regenerative additive slightly foamed by the chamber type 2 fluid nozzle 63 on about 600 kg of the regenerated aggregate in the mixer 2 (air amount: 3700NL / min, air pressure: 0.4 MPa, orifice diameter:: φ9 mm, spray width: W130 mm x L800 mm). After that, about 380 kg of new aggregate is charged into the mixer 2, and asphalt (foamed asphalt) foamed by a foaming device is charged into the mixer 2, and then kneaded with the mixer 2 to produce a regenerated asphalt mixture. ..

-Example 3:
Diffuse and spray 1 to 3 kg of the regenerative additive slightly foamed by the 2-fluid nozzle 63 on about 600 kg of the regenerated aggregate in the mixer 2 (air amount: 400NL / min, air pressure: 0.4 MPa, orifice diameter: φ3 mm, Spray width: W200mm x L400mm). Then, about 380 kg of new aggregate is put into the mixer 2, and asphalt (foamed asphalt) foamed by a foaming device is put into the mixer 2, and then kneaded with the mixer 2 to produce a regenerated asphalt mixture.

・ Comparative example:
A liquid regeneration additive of 1 to 3 kg is discharged to about 600 kg of the regenerated aggregate in the mixer 11. Then, about 380 kg of new aggregate is put into the mixer 11, and after the asphalt is discharged to the mixer 2, the mixture is kneaded with the mixer 11 to produce a regenerated asphalt mixture.
[Evaluation (test piece)]

Next, the results of various tests performed on Examples 1 to 3 and Comparative Examples are shown. The contents of the test are as follows.
・ Marshall stability test:
For Examples 1 to 3 and Comparative Examples compacted at a compaction temperature of 145 to 105 ° C, refer to "Pavement Survey / Test Method Handbook 2019 Edition (Author: Japan Road Association) Test Method Nos. B001, B008-1". Marshall stability tests were conducted in accordance with this.

FIG. 3 is a graph showing the sample density of the Marshall stability test, FIG. 3 (a) is a comparison between Example 1 and Comparative Example, and FIG. 3 (b) is a comparison of Example 2 and Comparative Example. For comparison, FIG. 3 (c) is a comparison between Example 3 and Comparative Example.

According to FIG. 3, in Examples 1 to 3, the bulk density is increased in a wide range of compaction temperatures (particularly, about 140 ° C. or lower) as compared with the comparative examples, and the bulk is increased as the compaction temperature decreases. The improvement in density is remarkable.

In particular, in Examples 1 to 3, the bulk density is increased as compared with the comparative examples, the dispersibility of the regenerating additive is excellent, and the regenerating additive is uniformly sprayed and mixed with the regenerated aggregate. It is presumed.

In particular, in Examples 1 and 2, the dispersibility of the regenerating additive is considered to be remarkable as compared with Example 3. Further, since the foamed asphalt is used in Example 2, it is considered that it contributes to the increase in bulk density as compared with Example 1. Further, in Examples 1 to 3, the decrease in bulk density is small even if the compaction temperature is decreased, as compared with the Comparative Example. This means that the bulk density can be secured even if the temperature at the time of pavement is lowered, and the workability at the time of construction is excellent.

・ Crush test:
Examples 1 to 3 and comparative examples compacted at a compaction temperature of 145 to 105 ° C are compressed in accordance with "Pavement Survey / Test Method Handbook 2019 Edition (Author: Japan Road Association) Test Method No. B006". A crack test was performed.

FIG. 4 is a graph showing the results of the crush test, FIG. 4 (a) is a comparison between Example 1 and Comparative Example, and FIG. 4 (b) is a comparison between Example 2 and Comparative Example. , FIG. 4 (c) is a comparison of Example 3 and Comparative Example.

The crushing coefficient is an index showing the properties (deterioration index) of the asphalt mixture, and is generally required to be 0.6 to 0.9 MPa / mm. In the case of a regenerated asphalt mixture, the smaller the value within this range, the better the properties of the old asphalt tend to be. According to FIG. 4, it can be seen that Examples 1 to 3 have a lower cracking coefficient than Comparative Examples.

In particular, in Examples 1 to 3, the cracking coefficient is lowered, the dispersibility of the regenerating additive is excellent, and it is presumed that the regenerating additive is uniformly sprayed and mixed with the regenerated aggregate. In particular, in Examples 1 and 2, the dispersibility of the regenerating additive is considered to be remarkable as compared with Example 3. Further, since the foamed asphalt is used in Example 2, it is considered that it contributes to the reduction of the crushing coefficient as compared with Example 1.

Here, regarding the effect when the foaming aid is mixed with the regeneration additive, except for Example 2 and the point that the foaming aid having a weight ratio of 1% with respect to the regeneration additive is mixed with the regeneration additive. This will be described in comparison with a specimen of a regenerated asphalt mixture obtained under the same conditions as in Example 2 (hereinafter referred to as “Example 4”).

FIG. 5A is a graph showing the specimen density of the Marshall stability test, and FIG. 5B is a graph showing the result of the crushing test. The numerical values do not match between Example 2 in FIGS. 3 to 4 and Example 2 in FIG. 5, but this is due to the difference between the regenerated aggregate and the new aggregate used for preparing the specimen. It is a thing.

According to FIG. 5A, in Example 4, the bulk density is increased in a wide range of compaction temperatures (particularly, about 135 ° C. or lower) as compared with Example 2, and as the compaction temperature decreases, the bulk density increases. , The improvement in bulk density is remarkable. Further, according to FIG. 5B, in Example 4, the cracking coefficient is lower than that in Example 2, the dispersibility of the regenerating additive is excellent, and the regenerating additive is a regenerated aggregate. It is presumed that they are evenly sprayed and mixed. As described above, it can be seen that the properties of the old asphalt can be further improved as compared with Example 2 by mixing the foaming aid with the regeneration additive.

[Evaluation (simple leveling)]
・ Core density, workability:
The core densities of Examples 1 to 3 and Comparative Examples were measured in accordance with "Pavement Survey / Test Method Handbook 2019 Edition (Author: Japan Road Association) Test Method No. B008". In addition, workability was evaluated for rake work under different temperature conditions (normal temperature, temperature reduction). Note that FIG. 6 shows the evaluation results of various construction conditions, core density and workability. FIG. 7 is a graph comparing the core densities of Examples 1 to 3 and Comparative Examples.

The "normal temperature" in FIG. 6 means a test at a temperature generally considered to be optimal for leveling. In this test, the "laying temperature" is set to about 160 ° C. and the temperature is changed. The pressure temperature was set to 150-160 ° C. In addition, "temperature reduction" means a test conducted at a temperature lower than the "normal temperature". In this test, the "laying temperature" is set to about 130 ° C and the rolling compaction temperature is 110 ° C. I set it to a degree.

In this test, a construction yard of W1m x L4m was prepared, and one area (W1m x L1.75m) was set to the normal temperature and the other area was set to (W1m x L1.75m) across the boundary of the center 50cm. It was set to a low temperature and leveled easily. The compaction was carried out by using a 1t hand guide roller with no vibration for one rotation pressure and then with vibration for two rotation pressures.

According to FIG. 6, in the laying performed at the "normal temperature", the workability was good in both Examples 1 to 3 and Comparative Examples. Further, according to FIG. 7, in the laying performed at the "normal temperature", when the core densities are compared, Examples 1 to 3 are better than the comparative examples, and the required densities are secured. In particular, Example 2 was remarkably excellent.

Next, the comparative example could not be constructed by laying at a temperature lower than the "normal temperature". Generally, when the leveling temperature and the rolling compaction temperature are low, the viscosity of the regenerated asphalt mixture becomes high, and the workability of the leveling tends to deteriorate. On the other hand, in Examples 1 to 3, the construction was possible, and in particular, in Examples 2 and 3, the construction was possible in the same manner as the normal temperature even at a low temperature. That is, according to Examples 1 to 3, construction can be performed at a lower temperature than usual, and while maintaining good quality and workability, for example, the temperature at the time of shipping the mixture can be lowered in the summer, or long-distance shipping can be performed. It is also possible to improve the working environment, such as making it possible.

Further, the present invention can be modified in various ways other than the above as long as it does not deviate from the spirit of the present invention, and it is natural that the present invention extends to the modified ones.

For example, the present invention is not limited to those applied to a system for producing a regenerated asphalt mixture obtained by mixing a regenerated aggregate, a new aggregate, a heated asphalt and a regenerating additive as described above, and a method thereof. It can also be applied to a production system and a method for producing a regenerated asphalt mixture (so-called 100% regenerated asphalt mixture) obtained by mixing a regenerated aggregate, a heated asphalt and a regenerating additive.

1 ・ ・ ・ Recycled asphalt mixture production system 2 ・ ・ ・ Mixer 3 ・ ・ ・ First measuring tank 4 ・ ・ ・ Second measuring tank 5 ・ ・ ・ Third measuring tank 51 ・ ・ ・ First pump 52 ・ ・ ・ Piping 53 ・ ・ ・ Nozzle 6 ・ ・ ・ Tank 61 ・ ・ ・ Second pump 62 ・ ・ ・ Piping 63 ・ ・ ・ 2 Fluid nozzle 64 ・ ・ ・ Compressor

Claims (4)

A method for producing a recycled asphalt mixture in which a recycled aggregate, a heated asphalt, and a recycling additive are mixed.
A method for producing a regenerated asphalt mixture, which comprises crushing the regenerating additive with a high-speed air flow and diffusing and spraying the regenerated aggregate in a state of being slightly foamed. The method for producing a regenerated asphalt mixture according to claim 1, wherein the regenerating additive is mixed with a foaming aid. A manufacturing system for recycled asphalt mixtures
A mixer that kneads recycled aggregate, additives for regeneration, and heated asphalt,
A two-fluid nozzle that diffuses and sprays the regeneration additive into the mixer in a state of being crushed by a high-speed air flow and slightly foamed.
A manufacturing system for recycled asphalt mixtures, characterized by being equipped with. The regenerated asphalt mixture manufacturing system according to claim 3, further comprising a foaming device for foaming the heated asphalt.

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