Waste plastic modified asphalt mixture with low environmental load and preparation method thereof

Abstract

The invention discloses a low-environmental-load waste plastic modified asphalt mixture and a preparation method thereof, and belongs to the technical field of asphalt modification and waste plastic recycling. The invention provides a waste plastic modified asphalt mixture with low environmental load. The waste plastic modified asphalt mixture is prepared from the following components: 995-1005 parts of aggregate, 40-50 parts of waste plastic modified asphalt, 2-3 parts of waste plastic particles, 7-9 parts of mineral powder and 1-5 parts of an inhibitor, the waste plastic modified asphalt comprises 100 parts of matrix asphalt, 1-7 parts of waste plastic powder and 1-5 parts of a compatibilizer. The waste plastic modified asphalt is prepared from the waste plastic powder, and the waste plastic particles are combined with the waste plastic modified asphalt in an aggregate manner to prepare the waste plastic modified asphalt mixture, so that the emission reduction effect of the waste plastic modified asphalt mixture is effectively improved, and the waste plastic modified asphalt mixture has good environmental protection benefits; and the anti-rutting capability of the asphalt can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of asphalt modification and waste plastic recycling, and in particular relates to a waste plastic modified asphalt mixture with low environmental load and a preparation method thereof. Background Art

[0002] With the rapid development of urbanization, asphalt, as an important material for road construction, plays an indispensable role in transportation infrastructure. However, traditional asphalt releases a large amount of volatile organic compounds (VOCs) during production and construction, which not only pollutes the air, but also threatens human health and the ecological environment. Especially under high temperature conditions, the volatile components in asphalt are more likely to evaporate into the atmosphere, causing long-term impacts on the environment. Therefore, reducing VOC emissions in asphalt production and construction has become an important issue to improve its environmental performance and sustainability.

[0003] At present, adding smoke suppressants for modification or direct dry mixing is one of the main methods to reduce VOC emissions from asphalt. For example, patent CN201510707450.9 discloses an asphalt smoke suppressant and a smoke suppressant asphalt based on the smoke suppressant and a preparation method thereof, and proposes the use of a smoke suppressant made of materials such as zeolite, diatomaceous earth, and graphite, which effectively reduces VOC emissions from asphalt under high temperature conditions. For example, patent CN202310380024.3 discloses an asphalt and a method for preparing asphalt, using nano-calcium carbonate as a smoke suppressant to reduce VOC emissions. However, these methods have problems with harsh preparation conditions, complex processes, or high environmental costs. In contrast, the use of waste plastics as modifiers not only has environmental advantages, but also has a certain inhibitory effect on VOC emissions due to its adsorption capacity, making it a research hotspot.

[0004] The recycling and utilization of waste plastics is an important measure to deal with resource shortages and environmental pollution. Plastics such as polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) have caused significant pressure on the environment due to their difficulty in degradation and high pollution. Applying waste plastics to asphalt modification can not only achieve resource utilization, but also improve asphalt performance. However, due to the large difference in the solubility parameters of asphalt and waste plastics, the compatibility between the two is poor, which in turn affects VOC emissions.

[0005] Therefore, how to use waste plastics to reduce the emission of volatile organic compounds in asphalt has become a technical problem that needs to be urgently solved in this field. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a waste plastic modified asphalt mixture with low environmental load and a preparation method thereof.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a waste plastic modified asphalt mixture with low environmental load, which comprises the following components by weight: 995-1005 parts of aggregate, 40-50 parts of waste plastic modified asphalt, 2-3 parts of waste plastic particles, 7-9 parts of mineral powder and 1-5 parts of inhibitor;

[0009] The waste plastic modified asphalt comprises, by weight, 100 parts of base asphalt, 1-7 parts of waste plastic powder and 1-5 parts of a compatibilizer.

[0010] The present invention adopts waste plastic powder to prepare waste plastic modified asphalt, and combines waste plastic particles with waste plastic modified asphalt in the form of aggregate to prepare waste plastic modified asphalt mixture, which effectively improves the emission reduction effect of the waste plastic modified asphalt mixture, has good environmental benefits, and can also effectively improve the anti-rutting ability of asphalt.

[0011] Preferably, the method for preparing waste plastic modified asphalt comprises the following steps:

[0012] S1. Melting the matrix asphalt at 160-170° C., then adding the waste plastic powder, stirring for 30-40 min at 170-180° C. and 1000-1500 rpm for swelling, to obtain a mixture of asphalt and waste plastic powder;

[0013] S2. The mixture of asphalt and waste plastic powder obtained in step S1 is sheared at 170-180° C. and 6000-8000 rpm for 30-60 min, and then a compatibilizer is added at 160-170° C. and 1000-1500 rpm, and stirred for 30-40 min to obtain the waste plastic modified asphalt.

[0014] Preferably, the particle size of the waste plastic powder is 200-300 mesh.

[0015] Preferably, the method for preparing the waste plastic powder comprises the following steps: melting and shearing the waste plastic, and then extruding, quenching, chopping, pulverizing and ultraviolet irradiating to obtain the waste plastic powder.

[0016] Although plastics have a certain ability to adsorb volatile organic compounds (VOCs), the adsorption performance of waste plastics that have not been pretreated is relatively limited. The adsorption capacity of plastics is affected by its particle size, pore structure, polarity, specific surface area and crystallinity. The present invention obtains waste plastic powder by melting and shearing waste plastics at high temperature, followed by extrusion, quenching, chopping, pulverization and ultraviolet irradiation, which reduces the crystallinity of plastics and increases the active surface of plastics. On the one hand, it can improve its adsorption speed, and on the other hand, it can improve the compatibility of waste plastic powder and matrix asphalt, thereby reducing the emission of volatile organic compounds in asphalt.

[0017] More preferably, the melting temperature is 130-140° C., the shearing rate is 100-200 rpm, and the shearing time is 5-10 min.

[0018] In the preparation process of waste plastic modified asphalt, waste plastic powder is directly added to asphalt to achieve modification. To ensure its uniform dispersion in asphalt, plastic should have a low melting point. Therefore, in the process of preparing waste plastic powder, a low melting temperature and a high shear rate need to be set, and then the extruded plastic particles are pulverized to improve their dispersion effect in asphalt.

[0019] Further preferably, the compatibilizer is selected from one or more of dioctyl maleate, furfural extracted oil, epoxidized soybean oil, and polyphosphoric acid.

[0020] Preferably, the particle size of the waste plastic particles is 5-7 mm.

[0021] Preferably, the method for preparing the waste plastic particles comprises the following steps: melting and shearing the waste plastic, and then extruding, quenching, chopping and ultraviolet irradiating to obtain the waste plastic particles.

[0022] The present invention obtains waste plastic particles by melting and shearing waste plastic at high temperature, followed by extrusion, quenching, shredding and ultraviolet irradiation, thereby reducing the crystallinity of the plastic, increasing the active surface of the plastic, and thus improving its adsorption speed.

[0023] More preferably, the melting temperature is 140-160° C., the shearing rate is 90-100 rpm, and the shearing time is 5-10 min.

[0024] In the preparation process of waste plastic modified asphalt mixture with low environmental load, waste plastic particles are mixed into asphalt as aggregate, so the waste plastic particles are required to have a higher melting point and hardness. To meet this requirement, in the process of preparing waste plastic particles, the present invention sets a higher melting temperature and a lower shear rate, and obtains waste plastic particles with a particle size in the range of 5-7mm by shredding, ensuring its stability with the waste plastic modified asphalt mixture.

[0025] Preferably, in the process of preparing waste plastic particles and preparing waste plastic powder, the intensity of ultraviolet irradiation is 10-300 mW / cm 2 The irradiation time is 10-30min.

[0026] The present invention enhances the polarity and adsorption capacity of plastics by ultraviolet irradiation. When the ultraviolet irradiation intensity is too low, the polarity enhancement effect is limited; when the ultraviolet irradiation intensity is too high, it may cause plastic degradation. Therefore, the ultraviolet irradiation intensity is controlled at 10-300mW / cm 2 The irradiation time should also be controlled within 10-30 minutes to avoid degradation caused by too long a time while ensuring sufficient modification effect.

[0027] Preferably, the particle size of the inhibitor is 300-400 mesh; the inhibitor is carbon black; and the carbon black is a by-product obtained by thermal cracking of waste plastics.

[0028] In order to reduce the emission of volatile organic compounds in waste plastic modified asphalt mixture and make full use of waste plastic, the present invention uses carbon black, a byproduct obtained by thermal cracking of waste plastic, as an inhibitor. When plastic is burned, carbon black is formed because part of the carbon cannot be burned. Since carbon black itself also has a certain adsorption effect, adding it as an inhibitor to waste plastic modified asphalt mixture not only improves the emission reduction effect of volatile organic compounds in waste plastic modified asphalt mixture, but also improves the recovery rate of waste plastic.

[0029] Preferably, the waste plastics include one or more of high-density polyethylene, low-density polyethylene, polypropylene, and polyethylene terephthalate, and have a crystallinity of 25-50%.

[0030] The waste plastic types used in the present invention are preferably high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), and polyethylene terephthalate (PET), which are mainly derived from waste garbage in life (water pipes, agricultural films, takeout boxes, beverage bottles). They are the most used types of plastic in life, not only easy to obtain, but also have high-temperature stability, which can improve the high-temperature stability of asphalt. In order to ensure that after the waste plastic is added to the asphalt, while ensuring better mechanical properties, it has a good VOC emission reduction effect, the present invention uses waste plastics with a crystallinity of 25-50%. Plastics within this crystallinity range can significantly improve the dispersion state of plastics in asphalt, and can also improve the high-temperature rutting resistance of asphalt and its mixture. At the same time, plastics with low crystallinity have better adsorption capacity and enhance the energy absorption effect on VOC.

[0031] The present invention also provides a method for preparing the waste plastic modified asphalt mixture with low environmental load described in the above technical solution, comprising the following steps:

[0032] (1) Weigh the required aggregate according to the grading, and then keep it at 160-170℃ for 1-3h to obtain the insulated aggregate;

[0033] (2) melting the waste plastic modified asphalt to obtain molten waste plastic modified asphalt;

[0034] (3) The insulated aggregate and part of the waste plastic particles in step (1) are mixed for the first time, and then the molten waste plastic modified asphalt in step (2) is added for the second time, and then the remaining part of the waste plastic particles and the inhibitor are added for the third time, and then the mineral powder is added for the fourth time to obtain the waste plastic modified asphalt mixture with low environmental load;

[0035] There is no order of precedence for steps (1) and (2).

[0036] Since plastics are easily degraded at high temperatures to produce volatile organic compounds, the present invention divides the waste plastic particles into two parts for addition, thereby avoiding the increase of VOCs emissions due to long-term mixing of the waste plastic particles.

[0037] Further preferably, in step (1), the grading is dense; further preferably, AC-16.

[0038] The aggregate of the present invention is densely matched, which can not only improve the compactness and anti-rutting performance of the waste plastic modified asphalt mixture, but also effectively enhance the ability to resist water damage, aging and cracking, while optimizing the use of asphalt, saving costs and improving construction performance.

[0039] Further preferably, in step (3), the part of waste plastic particles accounts for 50% of the mass of the total waste plastic particles.

[0040] Further preferably, in step (3), the first mixing time is 40-50 s; the second mixing time is 80-100 s; the third mixing time is 40-50 s; and the fourth mixing time is 80-100 s.

[0041] Compared with the prior art, the present invention has the following advantages and technical effects:

[0042] The present invention reduces the emission of volatile organic compounds in asphalt mixtures. Since plastics themselves have an adsorption effect, waste plastic particles are combined with waste plastic modified asphalt in the form of aggregates to prepare waste plastic modified asphalt mixtures, which effectively improves the emission reduction effect of the waste plastic modified asphalt mixtures, has good environmental benefits, and can also effectively improve the rutting resistance of asphalt. The addition of plastics improves the high-temperature stability and plastic deformation resistance of asphalt, and reduces rutting (i.e., road surface deformation) caused by traffic loads under high temperature environments.

[0043] The raw materials used in the present invention mainly come from waste plastics, which can not only effectively utilize waste plastics, but also promote the recycling and reuse of waste plastics, help alleviate the pressure of plastic waste, and promote the resource utilization of plastics, which is in line with the concepts of circular economy and sustainable development.

[0044] The addition of waste plastics can significantly change the physical properties of asphalt, enhancing its anti-volatility and weather resistance. On the one hand, the polymer properties of plastics enable it to form a stable composite structure with asphalt, inhibiting the release of volatile substances; on the other hand, the low volatility of plastics themselves further reduces asphalt VOC emissions. In addition, plastic-modified asphalt can extend the service life of roads, thereby reducing long-term environmental pollution. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with specific implementation methods.

[0047] Unless otherwise specified, parts in the embodiments of the present invention represent “parts by weight”.

[0048] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0049] Example 1

[0050] A waste plastic modified asphalt mixture with low environmental load consists of the following components by weight: 1000 parts of aggregate, 45 parts of waste plastic modified asphalt, 3 parts of waste polypropylene particles (30% crystallinity, 5-7mm particle size), 3 parts of carbon black (a byproduct obtained by thermal cracking of waste plastic, the same below) (300-400 mesh) and 8 parts of mineral powder; wherein the waste plastic modified asphalt consists of the following components by weight: 100 parts of 90# base asphalt, 5 parts of dioctyl maleate and 5 parts of waste polypropylene powder (30% crystallinity, 200-300 mesh).

[0051] The preparation method of waste polypropylene particles comprises the following specific steps:

[0052] S1, washing and drying the collected waste polypropylene plastics;

[0053] S2, put the dried waste polypropylene plastic into a screw extruder, and shear it at 150℃ and 100rpm. After 5 minutes, it is extruded, quenched, and chopped to form 5-7mm waste polypropylene particles. Then, the cooled waste polypropylene particles are placed in an irradiation chamber with an intensity of 200mW / cm 2 The waste polypropylene particles were obtained by irradiating the mixture under ultraviolet conditions for 20 minutes.

[0054] The preparation method of waste plastic modified asphalt, the specific steps are as follows:

[0055] A. Wash and dry the collected waste polypropylene plastics; put the dried waste polypropylene plastics into a screw extruder and shear them at 160°C and 150rpm. After 10 minutes, extrude, quench and chop them to form 2-3mm waste polypropylene particles. Then, pulverize the cooled waste polypropylene particles to control the particle size to 200-300 mesh, and then put them into a 200mW / cm 2 Irradiate under ultraviolet light conditions for 20 minutes to obtain waste polypropylene powder;

[0056] B. Put 90# matrix asphalt into an oven at 160°C to completely melt it, put it into a constant speed stirrer, and then slowly add the waste polypropylene powder obtained in step A, stir for 30 minutes at 180°C and 1000rpm to fully swell, and obtain a mixture of asphalt and waste polypropylene powder;

[0057] C. Place the mixture of asphalt obtained in step B and waste polypropylene powder into a high-speed shear emulsifier, perform high-speed shearing for 30 minutes at 180° C. and 6000 rpm, then add dioctyl maleate at 170° C. and 1000 rpm, and stir for 30 minutes to obtain waste plastic modified asphalt.

[0058] The method for preparing a waste plastic modified asphalt mixture with low environmental load comprises the following specific steps:

[0059] (1) Weigh the required aggregate according to the grade AC-16, and then keep it at 160°C for 3 hours to obtain the insulated aggregate;

[0060] (2) melting the waste plastic modified asphalt to obtain molten waste plastic modified asphalt;

[0061] (3) Add the insulated aggregate obtained in step (1) and 50% of waste polypropylene particles into a mixing pot and mix for 40 seconds; then add the molten waste plastic modified asphalt obtained in step (2) and mix for 100 seconds; then add the remaining waste plastic particles and carbon black and mix for 50 seconds; finally add mineral powder and mix for 80 seconds to obtain a waste plastic modified asphalt mixture with low environmental load.

[0062] Comparative Example 1

[0063] A waste plastic modified asphalt mixture consists of the following components by weight: 1000 parts of aggregate, 45 parts of waste plastic modified asphalt, 3 parts of waste polypropylene particles (crystallization degree 30%, particle size 5-7mm), 3 parts of carbon black (300-400 meshes) and 8 parts of mineral powder; wherein the waste plastic modified asphalt consists of the following components by weight: 100 parts of 90# base asphalt, 5 parts of dioctyl maleate and 5 parts of polypropylene powder (crystallization degree 30%, 200-300 meshes).

[0064] The preparation method of waste polypropylene particles comprises the following specific steps:

[0065] S1, washing and drying the collected waste polypropylene plastics;

[0066] S2: Place the dried waste polypropylene plastic in a 200mW / cm 2 The waste polypropylene was irradiated under ultraviolet light for 20 minutes and chopped into 5-7 mm waste polypropylene particles.

[0067] The preparation method of waste plastic modified asphalt, the specific steps are as follows:

[0068] A. Wash and dry the collected waste polypropylene plastics; grind the dried waste polypropylene plastics to control the particle size to 200-300 mesh, and then place them in an irradiation chamber with an intensity of 200mW / cm 2 The waste polypropylene particles are irradiated under ultraviolet light for 20 minutes, chopped to form 2-3 mm waste polypropylene particles, and then the cooled waste polypropylene particles are pulverized to control the particle size to 200-300 meshes to obtain waste polypropylene powder;

[0069] B. Put 90# matrix asphalt into an oven at 160°C to completely melt it, put it into a constant speed stirrer, and then slowly add the waste polypropylene powder obtained in step A, stir for 30 minutes at 180°C and 1000rpm to fully swell, and obtain a mixture of asphalt and waste polypropylene powder;

[0070] C. Place the mixture of asphalt obtained in step B and waste polypropylene powder into a high-speed shear emulsifier, perform high-speed shearing at 180° C. and 6000 rpm for 30 min, then add dioctyl maleate at 170° C. and 1000 rpm, and stir for 30 min to obtain waste plastic modified asphalt.

[0071] The preparation method of waste plastic modified asphalt mixture is the same as that in Example 1.

[0072] Example 2

[0073] A waste plastic modified asphalt mixture with low environmental load consists of the following components by weight: 1000 parts of aggregate, 45 parts of waste plastic modified asphalt, 3 parts of waste high-density polyethylene particles (crystallization degree 30%, particle size 5-7mm), 3 parts of carbon black (300-400 mesh) and 8 parts of mineral powder; wherein the waste plastic modified asphalt consists of the following components by weight: 100 parts of 90# base asphalt, 5 parts of furfural extracted oil and 5 parts of waste high-density polyethylene powder (crystallization degree 30%, 200-300 mesh).

[0074] The preparation method of waste high-density polyethylene particles is the same as the preparation method of waste polypropylene particles in Example 1, the preparation method of waste plastic modified asphalt and the preparation method of waste plastic modified asphalt mixture with low environmental load are the same as Example 1.

[0075] Comparative Example 2

[0076] A waste plastic modified asphalt mixture consists of the following components by weight: 1000 parts of aggregate, 45 parts of waste plastic modified asphalt, 3 parts of waste high-density polyethylene particles (crystallization degree 30%, particle size 5-7mm), 3 parts of carbon black (300-400 mesh) and 8 parts of mineral powder; wherein the waste plastic modified asphalt consists of the following components by weight: 100 parts of 90# base asphalt, 5 parts of furfural extracted oil and 5 parts of waste high-density polyethylene powder (crystallization degree 30%, 200-300 mesh).

[0077] The preparation method of waste high-density polyethylene particles comprises the following specific steps:

[0078] S1, washing and drying the collected waste high-density polyethylene plastics;

[0079] S2. Put the dried waste high-density polyethylene plastic into a screw extruder and shear it at 150°C and 100rpm. After 5 minutes, extrude, quench and chop to form 5-7mm waste high-density polyethylene particles.

[0080] The preparation method of waste plastic modified asphalt, the specific steps are as follows:

[0081] A. Wash and dry the collected waste high-density polyethylene plastics; put the dried waste high-density polyethylene plastics into a screw extruder, shear them at 160° C. and 150 rpm, extrude, quench and chop them after 10 minutes to form 2-3 mm waste high-density polyethylene particles, and then pulverize the cooled waste high-density polyethylene particles to control the particle size to 200-300 meshes to obtain waste high-density polyethylene powder;

[0082] B. Put 90# matrix asphalt into an oven at 160°C to completely melt it, put it into a constant speed stirrer, and then slowly add the waste high-density polyethylene powder obtained in step A, stir for 30 minutes at 180°C and 1000rpm to fully swell, and obtain a mixture of asphalt and waste high-density polyethylene powder;

[0083] C. Place the mixture of asphalt obtained in step B and waste high-density polyethylene powder into a high-speed shear emulsifier, high-speed shear for 30 minutes at 180° C. and 6000 rpm, then add furfural to extract oil at 170° C. and 1000 rpm, and stir for 30 minutes to obtain waste plastic modified asphalt.

[0084] The preparation method of waste plastic modified asphalt mixture is the same as that in Example 1.

[0085] Example 3

[0086] A waste plastic modified asphalt mixture with low environmental load consists of the following components by weight: 1000 parts of aggregate, 45 parts of waste plastic modified asphalt, 3 parts of waste polyethylene terephthalate particles (crystallization degree 30%, particle size 5-7mm), 3 parts of carbon black (300-400 meshes) and 8 parts of mineral powder; wherein the waste plastic modified asphalt consists of the following components by weight: 100 parts of 90# base asphalt, 5 parts of epoxidized soybean oil and 5 parts of polyethylene terephthalate powder (crystallization degree 30%, 200-300 meshes).

[0087] The preparation method of waste polyethylene terephthalate particles is the same as the preparation method of waste polypropylene particles in Example 1, the preparation method of waste plastic modified asphalt and the preparation method of waste plastic modified asphalt mixture with low environmental load are the same as Example 1.

[0088] Comparative Example 3

[0089] A waste plastic modified asphalt mixture consists of the following components by weight: 1000 parts of aggregate, 45 parts of waste plastic modified asphalt, 3 parts of waste polyethylene terephthalate particles (crystallization degree 30%, particle size 5-7mm), 3 parts of activated carbon (300-400 meshes) and 8 parts of mineral powder; wherein the waste plastic modified asphalt consists of the following components by weight: 100 parts of 90# base asphalt, 5 parts of epoxidized soybean oil and 5 parts of waste polyethylene terephthalate powder (crystallization degree 30%, 200-300 meshes).

[0090] The preparation method of waste polyethylene terephthalate particles is the same as the preparation method of waste polypropylene particles in Example 1, the preparation method of waste plastic modified asphalt and the preparation method of waste plastic modified asphalt mixture are the same as Example 1.

[0091] Comparative Example 4

[0092] A waste plastic modified asphalt mixture consists of the following components by weight: 1000 parts of aggregate, 45 parts of waste plastic modified asphalt, 3 parts of waste polyethylene terephthalate particles (crystallization degree 60%, particle size 5-7mm), 3 parts of carbon black (300-400 meshes) and 8 parts of mineral powder; wherein the waste plastic modified asphalt consists of the following components by weight: 100 parts of 90# base asphalt, 5 parts of epoxidized soybean oil and 5 parts of waste polyethylene terephthalate powder (crystallization degree 60%, 200-300 meshes).

[0093] The preparation method of waste polyethylene terephthalate particles is the same as the preparation method of waste polypropylene particles in Example 1, the preparation method of waste plastic modified asphalt and the preparation method of waste plastic modified asphalt mixture are the same as Example 1.

[0094] Example 4

[0095] A waste plastic modified asphalt mixture with low environmental load consists of the following components by weight: 1000 parts of aggregate, 45 parts of waste plastic modified asphalt, 3 parts of waste low-density polyethylene particles (crystallization degree 30%, particle size 5-7mm), 3 parts of carbon black (300-400 mesh) and 8 parts of mineral powder; wherein the waste plastic modified asphalt consists of the following components by weight: 100 parts of 90# base asphalt, 1 part of polyphosphoric acid and 5 parts of waste low-density polyethylene powder (crystallization degree 30%, 200-300 mesh).

[0096] The preparation method of waste low-density polyethylene particles is the same as the preparation method of waste polypropylene particles in Example 1, the preparation method of waste plastic modified asphalt and the preparation method of waste plastic modified asphalt mixture with low environmental load are the same as Example 1.

[0097] Comparative Example 5

[0098] A waste plastic modified asphalt mixture consists of the following components by weight: 1000 parts of aggregate, 45 parts of waste plastic modified asphalt, 3 parts of low-density polyethylene particles (crystallinity 30%, particle size 5-7mm), 3 parts of carbon black (300-400 mesh) and 8 parts of mineral powder; wherein the waste plastic modified asphalt consists of the following components by weight: 100 parts of 90# base asphalt, 1 part of polyphosphoric acid and 5 parts of waste low-density polyethylene powder (crystallinity 30%, 200-300 mesh).

[0099] The preparation method of low-density polyethylene particles is the same as the preparation method of waste polypropylene particles in Example 1, and the preparation method of waste plastic modified asphalt is the same as Example 1.

[0100] The preparation method of waste plastic modified asphalt mixture, the specific steps are as follows:

[0101] (1) Weigh the required aggregate according to the grade SMA-16, and then keep it at 160°C for 3 hours to obtain the insulated aggregate;

[0102] (2) melting the waste plastic modified asphalt to obtain molten waste plastic modified asphalt;

[0103] (3) Add the insulated aggregate obtained in step (1) and 50% of waste polypropylene particles into a mixing pot and mix for 40 seconds; then add the molten waste plastic modified asphalt obtained in step (2) and mix for 100 seconds; then add the remaining waste plastic particles and carbon black and mix for 50 seconds; finally add mineral powder and mix for 80 seconds to obtain a waste plastic modified asphalt mixture.

[0104] Comparative Example 6

[0105] An asphalt mixture consists of the following components, measured by weight: 1000 parts of aggregate, 45 parts of 90# base asphalt and 8 parts of mineral powder.

[0106] The preparation method of asphalt mixture includes the following specific steps:

[0107] (1) Weigh the required aggregate according to the grade SMA-16, and then keep it at 160°C for 3 hours to obtain the insulated aggregate;

[0108] (2) melting the 90# base asphalt to obtain a molten 90# base asphalt;

[0109] (3) Add the insulated aggregate obtained in step (1) into a mixing pot and mix for 40 seconds; then add the molten 90# base asphalt obtained in step (2) and mix for 100 seconds; finally add the mineral powder and mix for 80 seconds to obtain an asphalt mixture.

[0110] In order to verify the emission of volatile organic compounds of asphalt mixtures, the volatile organic compounds of the asphalt mixtures in Examples 1 to 4 and Comparative Examples 1 to 6 were collected according to the following method:

[0111] In order to simulate the actual situation in the transportation and paving stage of plant-mixed asphalt mixture, 1 kg of waste plastic modified asphalt mixture was mixed according to the specifications, and it was quickly and loosely distributed on the tray and placed in the asphalt mixture VOC collection device that had been preheated to 180°C. After the device was heated up and the temperature stabilized at the specified temperature (determined according to the construction temperature, the specified temperature of the base asphalt was 160°C, and the specified temperature of the waste plastic modified asphalt mixture was 180°C), the insulation timing began. During the 10-minute insulation process, the air bag was washed three times to ensure the purity of the asphalt VOC and the accuracy of the test. When the test insulation time reached 30 minutes, gas collection was started at a constant rate (1.2L / min) until the asphalt VOC filled the air bag.

[0112] The collected gas was analyzed by gas chromatography-mass spectrometry (GC-MS) to obtain the total emission concentration of volatile organic compounds. It was then subjected to performance testing in accordance with the Standard Test Methods for Asphalt and Asphalt Mixtures for Highway Engineering (JTG-E20-2011). The results are shown in Table 1.

[0113] Table 1 Emission of volatile organic compounds in Examples 1 to 4 and Comparative Examples 1 to 6

[0114]

[0115] Comparing Examples 1 to 4 and Comparative Example 6, Comparative Example 6 is an asphalt mixture prepared from base asphalt, while Examples 1 to 4 add waste plastics. It can be seen that the addition of waste plastics can significantly reduce the emission of volatile organic compounds in asphalt, and also enhance the high and low temperature performance of the asphalt mixture; By comparing Example 1 with Comparative Example 1, it can be seen that when preparing waste plastic particles and waste plastic powder, combining ultraviolet irradiation with melting and shearing can ensure good high and low temperature performance of the asphalt mixture while reducing the emission of volatile organic compounds of the asphalt mixture; By comparing Example 2 with Comparative Example 2, it can be seen that irradiating waste plastics with ultraviolet rays can increase the polarity of the plastics, which is beneficial to enhancing the plastic itself. The adsorption of the plastic itself is good, and adding it to the asphalt mixture reduces the emission of volatile organic compounds; by comparing Example 3 with Comparative Example 3, it can be seen that the carbon black derivative after plastic pyrolysis is used as an inhibitor, and the emission reduction effect is similar to that of activated carbon as an inhibitor, indicating the feasibility of using the carbon black product of plastic pyrolysis as an inhibitor; by comparing Example 3 with Comparative Example 4, it can be seen that plastics with low crystallinity have better adsorption capacity, so the use of plastics with low crystallinity is conducive to reducing the emission of volatile organic compounds in asphalt; by comparing Example 4 with Comparative Example 5, it can be seen that aggregates with different gradations have an impact on the emission of volatile organic compounds in asphalt, and the use of densely distributed aggregates has a better inhibitory effect. In addition, the embodiments of the present invention ensure good high and low temperature performance relative to the comparative examples.

[0116] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A waste plastic modified asphalt mixture with low environmental load, characterized in that: The composition includes the following components by weight: 995-1005 parts of aggregate, 40-50 parts of waste plastic modified asphalt, 2-3 parts of waste plastic particles, 7-9 parts of mineral powder and 1-5 parts of inhibitor; The waste plastic modified asphalt comprises, by weight, 100 parts of base asphalt, 1-7 parts of waste plastic powder and 1-5 parts of a compatibilizer.

2. The waste plastic modified asphalt mixture with low environmental load according to claim 1, characterized in that: The preparation method of the waste plastic modified asphalt comprises the following steps: S1. Melting the matrix asphalt at 160-170° C., then adding the waste plastic powder, stirring for 30-40 min at 170-180° C. and 1000-1500 rpm for swelling, to obtain a mixture of asphalt and waste plastic powder; S2. The mixture of asphalt and waste plastic powder obtained in step S1 is sheared at 170-180° C. and 6000-8000 rpm for 30-60 min, and then a compatibilizer is added at 160-170° C. and 1000-1500 rpm, and stirred for 30-40 min to obtain the waste plastic modified asphalt.

3. The waste plastic modified asphalt mixture with low environmental load according to claim 2, characterized in that: The particle size of the waste plastic powder is 200-300 meshes.

4. The waste plastic modified asphalt mixture with low environmental load according to claim 2, characterized in that: The method for preparing the waste plastic powder comprises the following steps: melting and shearing the waste plastic, and then extruding, quenching, chopping, pulverizing and irradiating with ultraviolet rays to obtain the waste plastic powder.

5. The waste plastic modified asphalt mixture with low environmental load according to claim 1, characterized in that: The particle size of the waste plastic particles is 5-7 mm.

6. The waste plastic modified asphalt mixture with low environmental load according to claim 1, characterized in that: The method for preparing the waste plastic particles comprises the following steps: melting and shearing the waste plastics, and then extruding, quenching, chopping and irradiating with ultraviolet rays to obtain the waste plastic particles.

7. The waste plastic modified asphalt mixture with low environmental load according to claim 4 or 6, characterized in that: In the process of preparing waste plastic particles and preparing waste plastic powder, the intensity of ultraviolet irradiation is 10-300mW / cm 2 The irradiation time is 10-30min.

8. The waste plastic modified asphalt mixture with low environmental load according to claim 1, characterized in that: The particle size of the inhibitor is 300-400 meshes; the inhibitor is carbon black; the carbon black is a by-product obtained after thermal cracking of waste plastics.

9. The waste plastic modified asphalt mixture with low environmental load according to claim 4 or 6, characterized in that: The waste plastics include one or more of high-density polyethylene, low-density polyethylene, polypropylene and polyethylene terephthalate, and the crystallinity is 25-50%.

10. The method for preparing a waste plastic modified asphalt mixture with low environmental load according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Weigh the required aggregate according to the grading, and then keep it at 160-170℃ for 1-3h to obtain the insulated aggregate; (2) melting the waste plastic modified asphalt to obtain molten waste plastic modified asphalt; (3) The insulated aggregate and part of the waste plastic particles in step (1) are mixed for the first time, and then the molten waste plastic modified asphalt in step (2) is added for the second time, and then the remaining part of the waste plastic particles and the inhibitor are added for the third time, and then the mineral powder is added for the fourth time to obtain the waste plastic modified asphalt mixture with low environmental load; There is no order of precedence for steps (1) and (2).

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