High-volume rubber powder modified asphalt and preparation method thereof

Abstract

The invention discloses high-dosage rubber powder modified asphalt and a preparation method thereof, and the rubber powder modified asphalt is prepared by adding 22-30 parts by weight of modified rubber powder into 100 parts by weight of road petroleum asphalt, the modified rubber powder is prepared from the following components in parts by weight: 85 to 95 parts of common rubber powder, 3 to 6 parts of phenolic resin, 0.6 to 1.2 parts of microcrystalline wax, 2 to 5 parts of naphthenic oil, 0.2 to 0.6 part of antioxidant and 0.2 to 0.6 part of EVA (Ethylene Vinyl Acetate). The preparation method comprises the following steps: (1) preparing the modified rubber powder; and (2) preparing the modified asphalt cement. According to the invention, co-melting and blending of the rubber powder and the asphalt are improved, the mixing amount of the rubber powder in the rubber asphalt can be obviously increased, the pavement and durability are greatly improved, the production cost and environmental pollution of the asphalt mixture are effectively reduced, and the asphalt mixture has economic and social double benefits, is simple in preparation process and has relatively high practical application value.

Description

Technical Field

[0001] The invention relates to the technical field of road construction materials, and more particularly to a high-content rubber powder modified asphalt and a preparation method thereof. Background Art

[0002] Rubber asphalt usually refers to a modified asphalt binder obtained by swelling asphalt with 12% to 20% tire rubber powder under high temperature and sufficient mixing conditions. In recent years, rubber modified asphalt has excellent low temperature stability, anti-aging and fatigue resistance, and has the advantages of extending the service life of the road, delaying reflective cracks and reducing noise. At the same time, it consumes a large number of waste tires, relieves environmental pressure, and has both economic and social benefits. The research and application of asphalt in the road field has received widespread attention.

[0003] Common rubber asphalt in the prior art is developed by mixing raw rubber powder directly with asphalt or by heat preservation after high-speed shearing. Since the surface network structure of common rubber powder is relatively complete and contains fewer reactive active groups, it is difficult to form a good chemical structure with asphalt, which leads to a large amount of accumulation and stratification of rubber powder particles in rubber asphalt. Therefore, the amount of rubber powder should not be too large, otherwise it will be difficult to process and affect the road performance of modified asphalt. In addition, as the amount of rubber powder increases, the accumulated rubber powder particles will continue to swell and degrade during the storage and transportation of modified asphalt, reducing the asphalt softening point and viscosity and other indicators, and ultimately causing the viscosity of the modified asphalt to increase and the workability to deteriorate, affecting the construction quality.

[0004] Based on the current technical defects of rubber asphalt, domestic and foreign road researchers have proposed and applied for relevant patents through in-depth research. For example, the Chinese invention patent (application number: 200610147692.8) discloses a high-temperature stable composite modified rubber asphalt. This method mainly adds petroleum resins and polypropylene wax and other petrochemical products to rubber asphalt. Although it can increase the softening point of rubber asphalt and improve construction and workability, the price of these additives is relatively high and the comprehensive production economy is poor. The Chinese invention patent (application number: 201010126676.7) discloses a method for preparing waste rubber powder modified asphalt that is resistant to high temperature storage. The method first blends waste rubber powder with PE plastic, extrudes it through a twin-screw extruder, and granulates it with a pelletizer. Finally, the prepared blending compatibilizer, rubber powder, asphalt and a small amount of sulfur are stirred by a high-speed shearing machine for 30 to 90 minutes to prepare waste rubber powder modified asphalt that is resistant to high temperature storage and stable. Although this method uses recycled waste plastics, the entire preparation process is relatively complicated and requires the addition of some new equipment, which increases the cost of rubber asphalt and increases the difficulty of application and promotion. Chinese invention patent CN1226351C discloses a desulfurized rubber powder modified asphalt, which is prepared by high-speed shear stirring or colloid mill grinding of desulfurized rubber powder, asphalt and compatibilizer at 160-210°C. The desulfurized rubber powder has good solubility and swelling in asphalt. At the same time, since there are certain active groups on the surface of the desulfurized rubber powder, it is conducive to chemical reaction with asphalt, improving the storage stability of rubber asphalt. However, the invention does not explain the source of the desulfurized rubber powder and the desulfurization method, so it is greatly affected by the source of raw materials and the degree of desulfurization, which is not conducive to industrial production. Chinese invention patent application CN1441005A "desulfurized rubber powder modified asphalt" discloses a production technology of desulfurized rubber powder modified asphalt, which is prepared by high-speed shear stirring or colloid mill grinding of desulfurized rubber powder, asphalt and additives at a relatively high temperature. The additive improves the compatibility of each component in the rubber powder modified asphalt, but because the rubber powder needs to be pre-desulfurized and then the desulfurized rubber powder is used as raw material for asphalt modification, the cost of the raw materials is high, and the cross-linking effect of the additives used is limited. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a high-content rubber powder modified asphalt and a preparation method thereof, wherein a new type of modified rubber powder particles are obtained by high-temperature mixing of rubber powder with phenolic resin, microcrystalline wax, cyclohexane oil, etc. The modified rubber powder particles are subjected to high-temperature shearing to achieve desulfurization and degradation of the rubber powder, and the cross-linked network structure is further destroyed. When added to asphalt, it can be quickly dispersed and dissolved in one body, so that even rubber asphalt with a large amount of rubber powder still maintains good storage stability.

[0006] On the other hand, by modifying the rubber powder and improving the preparation method of mixing it with asphalt, the modified effect of asphalt is more obvious, the road performance and durability are further improved, and the production cost and environmental pollution of asphalt and asphalt mixture are effectively reduced, which has both economic and social benefits. The preparation process is simple, and its various indicators meet the technical standards of rubber asphalt, and it has high practical application value.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A high-content rubber powder modified asphalt, calculated by weight, is prepared by adding 22-30 parts of modified rubber powder to 100 parts of road petroleum asphalt; the modified rubber powder is composed of the following components in weight ratio: rubber powder: phenolic resin: microcrystalline wax: cyclohexane oil: antioxidant: EVA = 85-95: 3-6: 0.6-1.2: 2-5: 0.2-0.6.

[0009] Preferably, the road petroleum asphalt is 70# to 90# common base asphalt.

[0010] Preferably, in the case of the common matrix asphalt, the modified rubber powder is added in an amount of 22 to 30 parts.

[0011] Preferably, the rubber powder is finely ground flocculent rubber powder from waste truck tires, with a fineness of 60 to 80 meshes.

[0012] Preferably, the free phenol content of the phenolic resin is 1% to 2.5%.

[0013] Preferably, the drop melting point of the microcrystalline wax is not less than 72°C.

[0014] Preferably, the antioxidant is an aromatic amine antioxidant or a hindered phenol antioxidant.

[0015] A method for preparing high-content rubber powder-modified asphalt of the present invention comprises the following steps:

[0016] (1) Weigh rubber powder, phenolic resin, microcrystalline wax, naphthenic oil, antioxidant, and EVA that meet the technical requirements according to weight;

[0017] (2) placing the tire rubber powder, phenolic resin, microcrystalline wax, EVA, antioxidant and other solid particles weighed in step (1) in a mixer and mixing;

[0018] (3) adding cyclohexane oil to the material obtained in step (2) and continuing to mix evenly to obtain modified rubber powder;

[0019] (4) Add the modified rubber powder obtained in step (3) into ordinary base asphalt in proportion, and use a high-speed shearing instrument to fully shear and mix the modified rubber powder and asphalt. The shearing is divided into two stages: pre-shearing and formal shearing. After the two-stage shearing is completed, take out the mixture.

[0020] (5) The mixture obtained in step (4) is placed in an oven at a specified temperature for development, and after the development is completed, a high-content rubber powder modified asphalt is obtained.

[0021] Preferably, the mixer in step (2) is set at a temperature of 90 to 100° C. and the mixing time is 15 to 20 min.

[0022] Preferably, the mixing time in step (3) is 10 min and the mixing temperature is 65-70°C.

[0023] Preferably, in step (4), the speed of the high-speed shearing instrument for pre-shearing is maintained at 3000±50r / r / min, the shearing time is 15min, and the temperature is controlled within the specified range of 180±3°C; in the formal shearing, the speed of the high-speed shearing instrument is selected to be 6000±50r / min, the shearing time is 90min, and the temperature is controlled within the specified range of 190±3°C.

[0024] Preferably, the specified temperature of the oven in step (5) is 120-125° C., and the development time is 1-2 hours.

[0025] Beneficial Effects

[0026] 1. Phenolic resin is a yellow, transparent, amorphous block substance with an average specific gravity of about 1.7. It is easily soluble in alcohol, insoluble in water, and stable to water, weak acid, and weak alkali solutions. The most important feature of phenolic resin is its high temperature resistance. Even at very high temperatures, it can maintain the integrity of its structure and dimensional stability. In addition, phenolic resin also has outstanding mechanical properties, chemical resistance, acid resistance, and bonding properties.

[0027] 2. Microcrystalline wax is white and granular, with a high melting point, is not brittle at low temperatures, has good adhesion, ductility and oil absorption properties, can enhance the oil absorption properties of rubber powder, and can undergo a grafting-like chemical reaction with the wax base in asphalt, thereby enhancing the stability of rubber powder and asphalt.

[0028] 3. Due to its saturated cyclic carbon chain structure, cyclohexane oil has the characteristics of low pour point, high density, high viscosity, and no toxic side effects. By utilizing the high solubility of cyclohexane oil and adding it to rubber powder, the plasticity of rubber can be greatly improved and the mutual solubility between rubber powder and asphalt can be enhanced.

[0029] 4. The mixer is a high-intensity intermittent mixing equipment developed on the basis of the open mixer. It uses the regular contraction of space produced by the relative movement of the designed internal blades to generate shear force. It is an ideal equipment for mixing, kneading, crushing, dispersing, and re-polymerizing various high-viscosity elastic-plastic materials and various chemical products. It has the advantages of uniform mixing, no dead angle, and high kneading efficiency.

[0030] 5. The performance improvement formula and preparation method of the rubber powder proposed in the present invention greatly improve the physical and chemical properties of the rubber powder itself. The modified rubber powder prepared by the high-temperature mixing process significantly improves the compatibility of the rubber powder with asphalt, promotes the swelling and degradation reaction rate of the rubber powder in asphalt, and enhances the chemical structure connection between the surface of the rubber powder particles and the asphalt. Macroscopically, the high-temperature stability and storage stability of the rubber-modified asphalt are greatly improved, and other road performance and durability are further improved. The formula is scientific and reasonable, the preparation process is simple, the overall cost is low and the output efficiency is high, and large-scale industrial production can be carried out. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0032] Figure 1 The accompanying drawing is a flow chart of the preparation of high-content rubber powder modified asphalt of the present invention;

[0033] Figure 2 The attached figure is the scanning electron microscope image of the two rubber powders. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0035] Example 1.

[0036] The raw materials are weighed in the ratio of rubber powder: phenolic resin: microcrystalline wax: naphthenic oil: antioxidant: EVA = 92: 3: 1: 3: 0.5. First, the rubber powder and solid granular materials such as phenolic resin are placed in a 100°C mixer and mixed for 15 minutes, and then the naphthenic oil is added. After uniform mixing, the mixing is continued for 10 minutes to obtain the modified rubber powder; 70# ordinary matrix asphalt is placed in a high-speed shearing machine container, and the modified rubber powder is added in batches according to 24% of the asphalt mass. The modified rubber powder and asphalt are fully sheared and mixed by a high-speed shearing instrument. The shearing is divided into two stages: pre-shearing and formal shearing. The speed of the high-speed shearing instrument for pre-shearing is maintained at 3000±50r / min, the shearing time is 15min, and the temperature is controlled within the specified range of 180±3℃; for formal shearing, the speed of the high-speed shearing instrument is selected to be 6000±50r / min, the shearing time is 90min, and the temperature is controlled within the specified range of 190±3℃. After the shearing is completed, the modified asphalt mixture is placed in an oven at 120°C for 1 hour to develop. After the development is completed, a high-content rubber powder modified asphalt is obtained.

[0037] Example 2.

[0038] The raw materials are weighed in the ratio of rubber powder: phenolic resin: microcrystalline wax: naphthenic oil: antioxidant: EVA = 92: 3: 1: 3: 0.5. First, the rubber powder and solid granular materials such as phenolic resin are placed in a 100℃ mixer and mixed for 15 minutes, and then the naphthenic oil is added. After uniform mixing, the mixing is continued for 10 minutes to obtain the modified rubber powder. 90# ordinary matrix asphalt is placed in a high-speed shearing machine container, and the modified rubber powder is added in batches according to 28% of the asphalt mass. The modified rubber powder and asphalt are fully sheared and mixed by a high-speed shearing instrument. The shearing is divided into two stages: pre-shearing and formal shearing. The speed of the high-speed shearing instrument for pre-shearing is maintained at 3000±50r / min, the shearing time is 15min, and the temperature is controlled within the specified range of 180±3℃; for formal shearing, the speed of the high-speed shearing instrument is selected to be 6000±50r / min, the shearing time is 90min, and the temperature is controlled within the specified range of 190±3℃. After the shearing is completed, the modified asphalt mixture is placed in an oven at 125°C for 2 hours to develop. After the development is completed, a high-content rubber powder modified asphalt is obtained.

[0039] Example 3.

[0040] The raw materials are weighed in the ratio of rubber powder: phenolic resin: microcrystalline wax: naphthenic oil: antioxidant: EVA = 89: 4.8: 1.2: 4.2: 0.8. First, the rubber powder and solid granular materials such as phenolic resin are placed in a 90°C mixer and mixed for 15 minutes, and then the naphthenic oil is added. After uniform mixing, the mixing is continued for 10 minutes to obtain the modified rubber powder; 70# ordinary matrix asphalt is placed in a high-speed shearing machine container, and the modified rubber powder is added in batches according to 28% of the asphalt mass. The modified rubber powder and asphalt are fully sheared and mixed by a high-speed shearing instrument. The shearing is divided into two stages: pre-shearing and formal shearing. The speed of the high-speed shearing instrument for pre-shearing is maintained at 3000±50r / min, the shearing time is 15min, and the temperature is controlled within the specified range of 180±3℃; for formal shearing, the speed of the high-speed shearing instrument is selected to be 6000±50r / min, the shearing time is 90min, and the temperature is controlled within the specified range of 190±3℃. After the shearing is completed, the modified asphalt mixture is placed in an oven at 120°C for development for 1.5 hours. After the development is completed, a high-content rubber powder modified asphalt is obtained.

[0041] Example 4.

[0042] The raw materials are weighed in the ratio of rubber powder: phenolic resin: microcrystalline wax: naphthenic oil: antioxidant: EVA = 89: 4.8: 1.2: 4.2: 0.8. First, the rubber powder and solid granular materials such as phenolic resin are placed in a 100°C mixer and mixed for 20 minutes, and then the naphthenic oil is added. After uniform mixing, the mixing is continued for 10 minutes to obtain the modified rubber powder; the 70# matrix asphalt is placed in a high-speed shearing machine container, and the modified rubber powder is added in batches according to 24% of the asphalt mass. The modified rubber powder and the asphalt are fully sheared and mixed by a high-speed shearing instrument. The shearing is divided into two stages: pre-shearing and formal shearing. The speed of the high-speed shearing instrument for pre-shearing is maintained at 3000±50r / min, the shearing time is 15min, and the temperature is controlled within the specified range of 180±3℃; for formal shearing, the speed of the high-speed shearing instrument is selected to be 6000±50r / r / min, the shearing time is 90min, and the temperature is controlled within the specified range of 190±3℃. After the shearing is completed, the modified asphalt mixture is placed in an oven at 120°C for development for 1.5 hours. After the development is completed, a high-content rubber powder modified asphalt is obtained.

[0043] Example 5.

[0044] The raw materials are weighed in the ratio of rubber powder: phenolic resin: microcrystalline wax: naphthenic oil: antioxidant: EVA = 92: 3: 1: 3: 0.5: 0.5. First, the rubber powder and phenolic resin and other solid granular materials are placed in a 90°C mixer for mixing for 10 minutes, and then the naphthenic oil is added. After uniform mixing, the mixing is continued for 15 minutes to obtain the modified rubber powder; 90# matrix asphalt is placed in a high-speed shearing machine container, and the modified rubber powder is added in batches according to 26% of the asphalt mass. The modified rubber powder and asphalt are fully sheared and mixed by a high-speed shearing instrument. The shearing is divided into two stages: pre-shearing and formal shearing. The speed of the high-speed shearing instrument for pre-shearing is maintained at 3000±50r / min, the shearing time is 15min, and the temperature is controlled within the specified range of 180±3℃; for formal shearing, the speed of the high-speed shearing instrument is selected to be 6000±50r / r / min, the shearing time is 90min, and the temperature is controlled within the specified range of 190±3℃. After the shearing is completed, the modified asphalt mixture is placed in an oven at 125°C for development for 1.5 hours. After the development is completed, a high-content rubber powder modified asphalt is obtained.

[0045] Comparative Example 1

[0046] Place 70# common base asphalt in a high-speed shearing machine container, add common rubber powder in batches according to 16% of the asphalt mass, and use a high-speed shearing instrument to fully shear and mix the rubber powder and asphalt. The shearing speed of the high-speed shearing instrument is maintained at 3000±50r / r / min, and the shearing time is 90min. After the shearing is completed, the modified asphalt mixture is placed in an oven at 125℃ for 1.5h to develop. After the development is completed, rubber modified asphalt is obtained.

[0047] Comparative Example 2

[0048] Place the ordinary rubber powder in a 100℃ mixer and mix for 15 minutes. After mixing, take it out and put it in a 25℃ constant temperature box to dry to constant weight to obtain mixed rubber powder; place 70# ordinary matrix asphalt in a high-speed shearing machine container, add the mixed rubber powder in batches according to 16% of the asphalt mass, and use a high-speed shearing instrument to fully shear and mix the rubber powder and asphalt. The shearing is divided into two stages: pre-shearing and formal shearing. The speed of the pre-shearing high-speed shearing instrument is maintained at 3000±50r / min, the shearing time is 15min, and the temperature is controlled within the specified range of 180±3℃; for formal shearing, the speed of the high-speed shearing instrument is selected to be 6000±50r / min, the shearing time is 90min, and the temperature is controlled within the specified range of 190±3℃. After shearing, the modified asphalt mixture is placed in a 125℃ oven for development for 1.5h, and rubber modified asphalt is obtained after development.

[0049] Comparative Example 3

[0050] The raw materials were weighed in a ratio of rubber powder: antioxidant: EVA = 99: 0.5: 0.5, and mixed in a 100℃ internal mixer for 15 minutes. After the internal mixing was completed, the raw materials were taken out and dried in a 25℃ constant temperature box to constant weight to obtain mixed rubber powder; 90# ordinary matrix asphalt was placed in a high-speed shearing machine container, and the mixed rubber powder was added in batches according to 16% of the asphalt mass. The mixed rubber powder and asphalt were fully sheared and mixed using a high-speed shearing instrument. The shearing was divided into two stages: pre-shearing and formal shearing. The speed of the high-speed shearing instrument for pre-shearing was maintained at 3000±50r / min, the shearing time was 15min, and the temperature was controlled within the specified range of 180±3℃; for formal shearing, the speed of the high-speed shearing instrument was selected to be 6000±50r / min, the shearing time was 90min, and the temperature was controlled within the specified range of 190±3℃. After the shearing was completed, the modified asphalt mixture was placed in an oven at 125℃ for 1.5h, and rubber modified asphalt was obtained after the development was completed.

[0051] Table 1. Comparison of the properties of rubber asphalt in Examples 1-5 and Comparative Examples 1-3

[0052] Table 1 Rubber modified asphalt performance test results

[0053]

[0054]

[0055] Based on the above experimental results, it can be known that although the amount of rubber powder in the rubber asphalt of the present invention is much higher than the ordinary rubber powder added to the rubber asphalt of the comparison case, due to the unique rubber powder modification formula and rubber asphalt preparation method of the present invention, the viscosity of the high-dosage modified rubber powder prepared therein does not increase significantly (indicating that the construction and workability are still good), and the softening point, needle penetration, elongation and other indicators are greatly improved.

[0056] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0057] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-content rubber powder modified asphalt, characterized in that: The high-content rubber powder modified asphalt is prepared by adding 22 to 30 parts of modified rubber powder to 100 parts of road petroleum asphalt; the modified rubber powder is composed of the following components in weight proportions: Composition: rubber powder: phenolic resin: microcrystalline wax: cyclohexane oil: antioxidant: EVA = 85 ~ 95: 3 ~ 6: 0.6 ~ 1.2: 2 ~ 5: 0.2 ~ 0.

6.

2. The high-content rubber powder modified asphalt according to claim 1, characterized in that: The road petroleum asphalt is 70#-90# common base asphalt, and the rubber powder content is 22-30 parts.

3. The high-content rubber powder modified asphalt according to claim 1, characterized in that: The rubber powder is finely ground flocculent rubber powder from waste truck tires, with a fineness of 60-80 meshes; the free phenol content of the phenolic resin is 1% to 2.5%; the drop melting point of the microcrystalline wax is not less than 72°C; and the antioxidant is an aromatic amine antioxidant or a hindered phenol antioxidant.

4. A method for preparing high-content rubber powder modified asphalt, used for preparing the high-content rubber powder modified asphalt according to any one of claims 1 to 3, characterized in that: The following process is used: (1) Weigh rubber powder, phenolic resin, microcrystalline wax, naphthenic oil, antioxidant, and EVA that meet the technical requirements according to weight; (2) placing the tire rubber powder, phenolic resin, microcrystalline wax, EVA, antioxidant and other solid particles weighed in step (1) in a mixer and mixing; (3) adding cyclohexane oil to the material obtained in step (2) and continuing to mix evenly to obtain modified rubber powder; (4) adding the modified rubber powder obtained in step (3) into the common base asphalt in proportion, Use a high-speed shearing instrument to fully shear and mix the modified rubber powder and asphalt. The shearing is divided into two stages: pre-shearing and formal shearing. After the two-stage shearing is completed, take out the mixture; The mixture obtained in step (4) is placed in an oven at a specified temperature for development, and after the development is completed, a high-content rubber powder modified asphalt is obtained.

5. The method for preparing high-content rubber powder modified asphalt according to claim 4, characterized in that: The mixer in step (2) is set at a temperature of 90 to 100° C. and a mixing time of 15 to 20 min.

6. The method for preparing high-content rubber powder modified asphalt according to claim 4, characterized in that: The mixer in step (3) is set at a temperature of 60-70° C. and a mixing time of 10 min.

7. The method for preparing high-content rubber powder modified asphalt according to claim 4, characterized in that: The shearing is divided into two steps: in step (4), the speed of the high-speed shearing instrument is maintained at 3000±50r / min, the shearing time is 15min, and the temperature is controlled within the specified range of 180±3°C; in the formal shearing, the speed of the high-speed shearing instrument is selected to be 6000±50r / min, the shearing time is 90min, and the temperature is controlled within the specified range of 190±3°C.

8. The method for preparing high-content rubber powder modified asphalt according to claim 4, characterized in that: The specified temperature of the oven in step (5) is 120-125° C., and the development time is 1-2 hours.

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