JPH0380922B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a heated asphalt mixture using asphalt pavement waste.

[Conventional technology]

The reuse of asphalt pavement waste materials (hereinafter referred to as waste materials) generated from repair work on existing asphalt pavements has been an effective way to make the most of limited resources since oil shocks, due to the dramatic rise in oil prices and unstable oil supplies. Due to the fact that the above-mentioned waste materials are designated as industrial waste under the ``Waste Disposal and Public Cleansing Act,'' and also from the standpoint of disposal site measures, it is important to recycle waste materials as recycled materials. The use of the recycled composite materials used is also rapidly developing and entering the practical stage.

The applications of the recycled composite material recycled from these waste materials include (1) recycled roadbed material by on-road mixing method for light pavement, (2) recycled roadbed material by plant mixing, (3) heat recycled composite material by plant mixing, etc. There are many uses for alternative materials, such as using recycled composite materials only for the surface layer of light pavement or simple pavement, and it is currently the mainstream.

In addition, regarding the manufacturing method of the recycled composite material, the proportion of waste wood as aggregate in the heat recycled composite material is 80%.
A drum dryer mixing method, which accounts for a high proportion of ~100% by weight, is generally adopted.

[Problem to be solved by the invention]

The drum dryer mixing method has the disadvantage that it is necessary to newly introduce a drum dryer mixing method in an existing asphalt mixture manufacturing plant, and requires a large amount of related equipment investment.

In addition, the asphalt in the waste material has aged considerably, but the waste material that is put into the heat-regenerated mixture is reheated in a drum dryer, but when trying to maintain it at 160°C, which is the temperature of a normal heated asphalt mixture, the waste material The asphalt deteriorates significantly.
Therefore, it is necessary to keep the temperature low and to inhibit the fluidity of the asphalt and the workability of the composite material (mixture), so a large amount of softener is added.
There is a pressing need to increase the penetration of asphalt. Even if such measures are taken, there still remains the problem that a fatal lack of compaction cannot be avoided and the work is difficult.

Furthermore, the quality of supplied waste materials differs depending on the time of existing pavement, collection location, etc., so it is difficult to uniformly respond to each individual as well as to the mixed state. There are problems with uneven quality such as variations, and as a result, only limited use is allowed for the top layer of the road surface.

On the other hand, approximately 80 million tons of asphalt mixtures are produced annually, and it has been pointed out that 12.5% to 25% of this, or 10 to 20 million tons, is generated as waste material. (Current status report on recycling of pavement waste materials = Japan Road Association - September 1981).
However, as mentioned above, conventional drum dryers
The mixing method requires a large amount of capital investment,
Furthermore, the quality of the recycled composite material is not desirable and its use is restricted, making it impossible to fully recycle and utilize the waste material.

On the other hand, even in equipment for producing heated asphalt mixtures using waste materials, especially in conventional dryers, the scraping blades provided on the inner circumferential surface of the drum are uniform, so that the flame of the burner does not reach deep. As a result, the falling aggregate blocks the flow of the recycled material, which is heated at a constant rate, and is discharged without being heated to the necessary and sufficient temperature to indirectly heat the recycled material at room temperature. There is a problem, especially
It was difficult to heat to a high temperature of 200°C to 250°C.

[Means for solving problems]

Although the proportion of recycled aggregate per unit weight is small, the present invention solves these difficult points and provides recycled composite material of stable quality with a small equipment cost and without the use of a softener. At the same time, the purpose of this invention is to provide a method and apparatus for producing a heated asphalt mixture that can be used in a wide range of applications on a par with new composite materials, and as a result, to reuse a large amount of waste materials. be. The basic idea of the method for manufacturing the heat exchange heated asphalt mixture (recycled composite material) according to the present invention is not to manufacture the mixture using 100% waste materials, but to produce a new mixture at a normal asphalt mixture production plant. This method attempts to reuse waste materials by mixing a certain percentage of waste materials at room temperature during mixing during the manufacturing process, and indirectly heating the materials through heat radiation from the heated new mixture. As a method (1) New aggregate is dropped into the dryer at a uniform scattering density on the inner wall above the height center in the part closer to the aggregate input port than the flame part, and A heating process in which the recycled material is heated to a range of 200°C to 250°C depending on the amount and temperature of the recycled material to be mixed on the auxiliary vane, and the new aggregate heated to 200°C to 250°C in a hot elevator is lifted to the screen position. a sieving process in which the new aggregate lifted by the screen is sent to a sieved aggregate measuring tank; a recycled material input process in which the recycled material is sent from the recycled material bin to the aggregate measuring tank; a filler and The process of adding additives to send asphalt to each measuring tank, and measuring 10 to 45 parts by weight of recycled material at room temperature to 55 to 90 parts by weight of new aggregate in the aggregate measuring tank, and adding filler and asphalt in each measuring tank. The process involves measuring the amount and sending it from each measuring tank to the mixer, and after dry mixing the new aggregate and recycled material in the mixer, filler and asphalt are added, wet mixing, and discharged as a heated asphalt mixture at approximately 160℃. A method for producing a heated asphalt mixture using asphalt pavement waste, comprising a kneading step.

[Effect]

Even though the dryer is the same size and has the same burner capacity as a conventional dryer, the heated aggregate is scraped up by the rotation of a rotating body with auxiliary blades placed around the flame part on the periphery of the rotating body. However, the scraped aggregate is not allowed to fall directly above the flame, but is heated by the high temperature directly above the flame on the auxiliary blade, and the flame tip is blocked by the falling aggregate. Because it is possible to heat the inside of the rotating body without heat, the new aggregate can be
Can be heated to high temperatures of °C.

The new aggregate heated to 200°C to 250°C is temporarily stored in a hot bin and weighed in a predetermined amount in the aggregate measuring tank below, and the recycled material at room temperature is also mixed into 100 parts of the mixture in the aggregate measuring tank. against 10
~45 parts by weight are weighed and kneaded in a mixer, and the room temperature recycled material is heated by heat exchange with the heat of the new aggregate to about 180°C. Therefore, the heating temperature of the new aggregate is set within the range of 200°C to 250°C in accordance with the mixed amount and temperature of the recycled material.

Next, a predetermined amount of stone powder or other filler at room temperature and heated new asphalt are put into a mixer and mixed.
A heated asphalt mixture using asphalt pavement waste material with a temperature of around 160°C is produced through heat exchange.

〔Example〕

Hereinafter, a method for producing a heated asphalt mixture using asphalt pavement waste according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a process diagram showing an example of a method for producing a heated asphalt mixture using asphalt pavement waste materials according to the present invention.

In this Figure 1, the method for producing a heated asphalt mixture using asphalt pavement waste is as follows:
The new aggregate 16 is lowered to the dryer 2 at a uniform scattering density on the inner wall portion 2i above the height center at a portion closer to the aggregate input port 2j than the flame portion 21h, and in the flame portion 2h above the flame of the burner 2d. From 200℃ depending on the amount and temperature of recycled material mixed on the auxiliary blade.
A heating process 3l in which the new aggregate 16 is heated to a temperature in the range of 25°C, a lifting process in which the new aggregate 16 heated to 200°C to 250°C by the hot elevator 11 is lifted to the screen 10 position, and the new aggregate 16 lifted by the screen 10 is A sieving step 33 in which the aggregate 16 is sent to the sieved aggregate measuring tank 4b, and the recycled material 1 is transferred from the recycled material bin 8 to the aggregate measuring tank 4b.
Regenerated element feeding step 34 to send filler and asphalt to each measuring tank 4a,
4c, and in the aggregate measuring tank 4b, 16:55 to 90 parts by weight of new aggregate are weighed to 1:10 to 45 parts by weight of recycled material at room temperature, and in each measuring tank 4a and 4c, The amount of filler and asphalt to be added is measured in each measuring tank 4a, 4b, 4.
a metering process 36 for sending from c to mixer 3, and a kneading process in which new aggregate 16 and recycled material 1 are dry mixed in mixer 3, filler and asphalt are added, wet mixed and discharged as heated asphalt at approximately 160°C. 37, and a method for producing a heated asphalt mixture using asphalt pavement waste, characterized by comprising:

Furthermore, the asphalt mixture manufacturing plant used in the present invention, etc. will be explained.

FIG. 2 is a schematic diagram of an asphalt mixture manufacturing plant.

The asphalt mixture manufacturing equipment in the asphalt mixture manufacturing plant uses new aggregate 16 in the main part.
a dryer 2 for heating to 200°C to 250°C;
Mixers 3 of mixing devices 3, 4a, 4b, 4c, 8, 9, and 10 are provided, and measuring tanks 4a, 4b, and 4c are provided above the mixers 3. The measuring tank is divided into 4a for stone powder, 4b for aggregate, and 4c for asphalt, and a stone powder bin 6 for storing filler such as stone powder via a stone powder elevator 5 is disposed above the stone powder measuring tank 4a. At the upper part of the aggregate measuring tank 4b, there are disposed a recycled material pin 8 which is accommodated via a recycled material hopper 7, and a hot bin 9 which is kept warm and accommodates the new aggregate heated by the dryer 2.

A screen 10 for classification is arranged above the hot bin 9, and the screen 10 and the dryer 2
A hot elevator 11 for transporting new aggregate is disposed between the discharge port and the discharge port. The dryer 2 has a dry cyclone 13 between it and the chimney 12.
A wet cyclone 14 and an exhaust fan 15 are installed in sequence,
A hot air pipe 13a from the dry cyclone 13 is connected to the hot elevator 11 so that the hot elevator 11 can be heated with hot air.

Further, the recycled material hopper 7 discharges a predetermined amount of recycled material 1 using a belt feeder (not shown), and conveys the recycled material 1 to a recycled material bin 8 (not shown) for storage by a belt conveyor (not shown). When a command is issued from the operation room of the plant main body (not shown), the screen conveyor (not shown) of the recycled material bin 8 is activated, and the recycled material 1 is dropped into the aggregate measuring tank 4b of the mixing device, reducing the total amount of the mixture to 100 parts. It is weighed at a ratio of 10 to 45 parts by weight, and separately from the hot bin 9 at 200℃~
The new aggregate 16 heated to 250° C. is dropped into the aggregate measuring tank 4b and cumulatively weighed. After being weighed, the new aggregate 16 and the recycled material 1, which were put into the mixer 3, are dry mixed to exchange heat, and the mixture of the new aggregate 16 and the recycled material 1 is maintained at around 180°C as a whole. Ru. The heating temperature of the new aggregate is determined by the heat exchange calorie calculation calculated backwards from this 180°C.
The heating temperature is determined from the amount and temperature of 200℃ to 250℃.

Next, stone powder is dropped as a filler from the stone powder bottle 6 into the stone powder measuring tank 4a, and a predetermined amount is measured.
A predetermined amount of new asphalt that has been heated from the asphalt measuring tank 4c is also poured into the mixer 3, and wet-mixed with the mixture to produce a heated asphalt mixture using asphalt pavement waste with a temperature of around 160°C. Manufactured.

The dryer 2 is installed on a support 17, and has a rotating body 2c between the base end structure 2a and the upper end structure 2b.
is rotatably mounted around the cylinder via a drive mechanism (not shown). The code 2d in the drawing is a burner, 2
e is a flame, 2f is an outlet, and 2g is an inlet.

The rotating body 2c is a cylindrical body, and is divided into a flame part 2h, an inner wall part 2i, and an inlet part 2j from the base end, and the flame part 2h is connected to the rotating body 2c as shown in FIG.
Auxiliary blades 18 having a substantially L-shaped cross section and having a dish portion facing parallel to the circumferential surface having a longer width than the height of a base portion facing in the radial direction are arranged radially with respect to the cylinder center P on the circumferential surface of the inner wall of the cylinder. There is.

In the inner wall portion 2i, as shown in FIG. 5, scraping blades 19 are arranged and arranged radially with respect to the cylindrical center P on the circumferential surface of the cylindrical inner wall. As shown in FIG. 7, the raking blade 19 has a base portion 19a having a substantially L-shaped cross section, and shelves 19b, 19b arranged in a cage-like manner to form a substantially U-shaped cross section. Reference numeral 19c in the figure is a fixing member for the shelf board.

As shown in FIGS. 6 and 8, in the inlet 2j, plate-shaped backflow prevention blades 20 are provided on the inner wall of the cylinder radially with respect to the cylinder center P and with respect to the axis passing through the cylinder center P. They are arranged in an inclined manner. However, the flame 2e is adjusted to maintain the atmosphere inside the cylinder at 250 to 300℃, and the new aggregate 16 is fed from the input port 2g.
is input to rotate the rotating body 2c. At this time,
In the backflow prevention blade 20, the new aggregate 16 is the upper end structure 2.
This prevents backflow in the b direction and transports the aggregate to the center of the dryer.

The scraping blades 19 scrape up the aggregate falling on the bottom of the inner wall of the rotating body 2c upward along the peripheral wall and scrape up new aggregate 16 from between the shelves 19b as it reaches the upper part.
is dropped, which causes the rotating body 2 to fall as shown in Figure 9.
(c) It is made to fall evenly like hail on the cylinder body, and the new aggregate 16 is made to averagely promote heat absorption.

As the rotating body 2c rotates, new aggregate enters the input port 2.
The flame part 2 is moved little by little in the downward direction of the rotating body 2c from near g, that is, in the direction of the flame part 2h, is raked up, and is sufficiently heated while moving further in the downward direction of the inclination.
h.

Next, in the flame section 2h, the new aggregate 16 is scooped up along the peripheral wall by the auxiliary blades 18, and the new aggregate 16 is dropped at the side of the cylinder without falling at the top of the cylinder of the rotating body 2c. By doing so, the progress of the flame 2e is not inhibited by the aggregate, and thereby the inside of the rotating body can be maintained at a high temperature.

New aggregate 1 scraped up by auxiliary blades 18
6 is heated in a high temperature atmosphere on the auxiliary blade 18 directly above the flame 2e in the flame section 2h, and the coarse aggregate and fine aggregate are brought into close contact with the peripheral wall of the rotating body 2c and the auxiliary blade 18. Heat exchange between the aggregates also takes place, allowing local temperatures to be easily reached.

With the above configuration, the new aggregate 16 is transferred to the dryer 2
It is heated to an arbitrary temperature in the range of 200 to 250°C and discharged from the discharge port 2f, transported to the screen 10 by the hot elevator 11, classified, and temporarily stored in the classified hot bin 9 below. Ru. Since the hot elevator 11 is kept warm by sending the exhaust heat from the dryer 2 through the dry cyclone 13, the new aggregate heated by the dryer 2 does not cool down in the hot elevator 11, and the hot bin 9 is also kept warm. It is kept warm.

The setting of the heating temperature of the new aggregate 16 takes into consideration the outside temperature, the required transportation time, and the like. Temperature 19-20℃
In the case of
200℃ at 10%, 220℃ at 20%, 235 at 30%
When the temperature is 45%, it is 250℃, which is a guideline to bring the target temperature of the heated asphalt mixture closer to 160℃.

The recycled material hopper 7 absorbs the recycled material 1, which is made of waste material scraped from the general asphalt pavement body, or classified asphalt pavement waste material obtained by crushing waste material cut by a cutting machine with a crusher. , and supply it to the recycled material bin 8 as required.

The amount of the recycled material 1 varies depending on the intended use of the mixture.
In the range of 10 to 45 parts by weight per 100 parts, the quality of the waste material,
The target temperature of the final mixture will be set at 160°C, taking into account the particle size of the new aggregate, temperature fluctuations, etc.

The amount of filler such as stone powder is determined by considering the quality and quantity of the recycled material 1, and the same applies to the amount of new asphalt, but generally the asphalt content in pavement waste is 5 to 7% by weight of the total weight. Therefore, in the case of recycled material 1, new asphalt is added in an amount equal to the value obtained by subtracting the value obtained by multiplying the extracted asphalt amount by the mixing ratio.

The heated asphalt mixture thus produced can be used in the same way as conventional mixtures. The mechanical properties of the road surface paved with this mixture were examined in accordance with the Asphalt Pavement Guidelines (Japan Road Association, revised edition in 1973), including a marshal test (test temperature 60°C) and a wheel tracking test (test temperature 60℃, ground pressure 6.4Kg/cm ² ), and repeated bending test (specimen size 3 x 3 x 40cm, span
30cm two-point loading method, frequency 5Hz) results as the first
It is shown in FIG. 1, FIG. 12, and FIG. 13. Looking at Figure 11, the void ratio is not much different between the new mixture and the mixture containing waste materials, and the stability is higher than that of the new mixture at 20%, 30%, 40% (%), and 40% cutting waste material, respectively. 1.29x, 1.29x, 1.15x,
It is 1.10 times higher than the new mixture, and it is clear that it is not inferior to the new mixture, but is actually higher than the new mixture, regardless of the type of waste material. In addition, the index of Nijboer's elastic modulus, which is obtained by dividing the stability after 48-hour water immersion by the flow value and multiplying it by 16, is 736/28×16 = 449 for the new mixture, and the crushing waste material mixture ratio is 20, 30, 40 (% ), 607, 548, and 40% cutting waste mixed rate, respectively.
514,459, indicating that the value is equal to or higher than that of the new mixture.

In Figure 12, the dynamic stability of the mixture containing 20 to 45% recycled material 1 is about 1.5 times higher than that of the new mixture (new composite material), and the dynamic stability after one year of construction is also It is large in size, has excellent flow resistance, and can be said to be extremely stable against kneading after use.

In Fig. 12, the number of repeated failures of the mixture (recycled composite material) according to the present invention at low temperatures increases as the percentage of recycled materials (waste materials) is increased; According to the results of this correlation, it can be said that the mixture according to the present invention has a greater number of fractures than the new mixture, and is superior in durability at low temperatures. Based on the above, the heated asphalt mixture using recycled materials produced according to the present invention has the same or better quality than the new composite material that does not use recycled materials, based on the results of various physical property tests. be.

〔Effect of the invention〕

The present invention has the following effects.

(1) By arranging auxiliary blades in the flame part on the circumference of the rotating body of the dryer, the flame of the burner is prevented from being blocked by falling aggregate, so that the same burner capacity can be maintained inside the rotating body. As a result, the aggregate can be maintained at higher temperatures at
It became possible to heat to a high temperature of 250℃.
As a result, it was possible to produce a heated asphalt mixture containing pavement waste at a high ratio of 45 parts by weight based on the total weight using existing equipment, and the heated asphalt was no inferior to the new heated asphalt mixture. It has the effect of making it possible to effectively utilize the estimated 20 million tons of paving waste material per year.

(2) Introducing the drum dryer mixing method, since recycled materials made from some waste materials are mixed in at room temperature during mixing, and heated indirectly by the heat released from the heated new aggregate. Recycled composite materials can be manufactured using waste materials by simply installing a device in a conventional asphalt plant that automatically feeds the recycled materials into a mixer at room temperature without the need for equipment, reducing capital investment. In addition, waste materials that should be discarded can be taken home and recycled, which has the effect of reducing manufacturing costs.

(3) A softener is not required to correct the penetration as in the drum dryer mixing method, and the adverse effects on the recycled mixture due to fluctuations in the quality of waste materials are extremely small.

The dynamic stability of the heated asphalt mixture obtained is about 1.5 times higher than that of the new mixture (new composite material), and the dynamic stability after one year of construction is also higher, and it has excellent flow resistance. It is also extremely stable against kneading after it is put into service.

(4) Regarding the number of repeated failures of the recycled heated asphalt mixture at low temperatures, the higher the percentage of waste mixed in, the higher the number of failures.
In addition, the results one year after construction showed that this correlation showed that the number of failures was greater for the inventive mixture than for the new composite material.
Excellent durability at low temperatures.

[Brief explanation of drawings]

The drawings relate to embodiments of the present invention, and FIG. 1 is a process diagram, FIG. 2 is a schematic diagram of an asphalt mixture manufacturing plant, FIG. 3 is a sectional view of a dryer, and FIG.
AA sectional view in the figure, FIG. 5 is a BB sectional view in FIG. 3, and FIG. 6 is a C-C sectional view in FIG. 2.
7 is a perspective view of the raking blade, FIG. 8 is a perspective view of the backflow prevention blade, FIG. 9 is a BB sectional view in FIG. Figure 3 shows the A-A cross-sectional view when the body rotates, Figure 11 shows the results of the marshal stability test, Figure 12 shows the deformation rate of cut specimens, and Figure 13 shows the results of the destructive bending test. be. DESCRIPTION OF SYMBOLS 1... Recycled material, 2... Dryer, 2a... Base end structure, 2b... Upper end structure, 2c... Rotating body, 2d... Burner, 2e... Flame, 2f... Exhaust port, 2g... ...Inlet, 2h...Flame section, 2i...
...Inner wall part, 2j...Inlet part, 3...Mixer, 4
a... Stone powder measuring tank, 4b... Aggregate measuring tank, 4c...
...Asphalt measuring tank, 5...Stone powder elevator,
6... Stone powder bottle, 7... Recycled material hoppa, 8...
Recycled material bin, 9...hot bin, 10...screen, 3, 4a, 4b, 4c, 8, 9, 10...
...Mixing material device, 11...Hot elevator, 12...
... Chimney, 13 ... Dry cyclone, 14 ... Wet cyclone, 15 ... Exhaust fan, 16 ... New aggregate, 17 ... Support column, 19a ... Base part, 19b ...
... Shelf board, 19c ... Fixing material, 20 ... Backflow prevention blade, 31 ... Heating process, 32 ... Lifting process, 33
...Sieving process, 34...Recycled material inputting process, 3
5...additive material introduction process, 36...measuring process, 37
...Kneading process.

Claims (1)

[Scope of Claims] 1. New aggregate is lowered into the dryer at a uniform scattering density on the inner wall part above the height center in a part closer to the aggregate input port than the flame part, and in the part above the flame of the burner in the flame part. A heating process in which the recycled material is heated to a range of 200°C to 250°C depending on the amount and temperature of the recycled material to be mixed on the auxiliary vane, and the new aggregate heated to 200°C to 250°C in a hot elevator is lifted to the screen position. a sieving process in which the new aggregate lifted by the screen is sent to a sieved aggregate measuring tank; a recycled material input process in which the recycled material is sent from the recycled material bin to the aggregate measuring tank; a filler and The process of adding additives to send asphalt to each measuring tank, and measuring 10 to 45 parts by weight of recycled material at room temperature to 55 to 90 parts by weight of new aggregate in the aggregate measuring tank, and adding filler and asphalt in each measuring tank. The process involves measuring the amount and sending it from each measuring tank to the mixer, and after dry mixing the new aggregate and recycled material in the mixer, filler and asphalt are added, wet mixing, and discharged as a heated asphalt mixture at approximately 160℃. A method for producing a heated asphalt mixture using asphalt pavement waste, comprising a kneading step.