High-viscosity high-elasticity modified asphalt and preparation method thereof

Abstract

The invention belongs to the technical field of road materials, and particularly relates to a preparation method of high-viscosity and high-elasticity modified asphalt, which is characterized by comprising the following steps: (1) carrying out desulfurization treatment on waste tire powder until the crosslinking degree of the desulfurized waste tire powder is reduced to be not higher than 50% of the crosslinking degree of the waste tire powder; and (2) mixing 70-85 parts by weight of matrix asphalt, 5-10 parts by weight of desulfurized waste tire powder, 2-6 parts by weight of a linear SBS elastomer, 2-5 parts by weight of aminosilane surface modified nano SiO2, 0.5-1.5 parts by weight of polyphosphoric acid, 5-12 parts by weight of extracted aromatic oil and 0.5-1 part by weight of an antioxidant to obtain the high-viscosity and high-elasticity modified asphalt. The defects of the existing rubber powder or SBS modified asphalt in the aspects of high-temperature viscosity, long-term storage stability and low-temperature crack resistance are overcome, so that the asphalt has high viscosity, high stability and low-temperature toughness, thereby improving the performance of the asphalt and prolonging the service life of the asphalt.

Description

Technical Field

[0001] This invention belongs to the field of road materials technology, specifically relating to a high-viscosity, high-elasticity modified asphalt and its preparation method. Background Technology

[0002] With the large-scale construction of highways, heavy-duty traffic, and bridge and tunnel projects, asphalt concrete pavement has become the mainstream structure due to its driving comfort and ease of construction. However, the surge in traffic volume, frequent overloading, and the occurrence of extreme weather conditions have exposed the inherent defects of base asphalt, such as its high temperature sensitivity and narrow plastic range, leading to widespread problems such as rutting, early cracking, and water damage. High-viscosity and high-elasticity modified asphalt, due to its high dynamic viscosity at 60℃ and excellent elastic recovery properties, is widely used in special scenarios such as drainage and noise reduction pavements, steel bridge deck paving, and airport runways.

[0003] Existing high-viscosity modification technologies mainly include three routes: TPS high-viscosity agent blending, SBS / resin composite modification, and SBS / rubber powder composite modification. While TPS modification can achieve a viscosity >2×10⁻⁶ at 60℃... 4 Pa·s, but its dosage of about 12wt% leads to high cost; the SBS / resin system requires a large amount of elastomer and resin to meet the high temperature viscosity index, which also significantly increases the cost; the SBS / rubber powder route can partially utilize solid waste, but the high processing temperature and severe thermal storage stratification bring difficulties to production and construction.

[0004] CN113861708A, CN113004707A, and CN109722047A employ solutions such as "base asphalt + anti-aging agent + modifier + stabilizer," "SBS / high viscosity resin compound," and "plasticizer / water system," respectively. While these solutions improve some performance aspects, they generally suffer from insufficient high-temperature viscosity or poor storage stability. Furthermore, insufficient activation of the rubber powder and agglomeration of inorganic nanoparticles also limit performance improvement.

[0005] Therefore, there is an urgent need to develop a high-performance modified asphalt that simultaneously achieves high-temperature viscosity, long-term storage stability, and low-temperature toughness. To address these challenges, this invention proposes a ternary synergistic technology route of "hydrophobic nano-SiO2—desulfurized waste rubber powder—polyphosphate PPA." By constructing an inorganic-organic multi-scale network and a chemical cross-linking synergistic mechanism, this approach overcomes existing technological bottlenecks and provides a new solution for road materials used in heavy-duty traffic and extreme climate conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a high-viscosity, high-elasticity modified asphalt and its preparation method. This invention overcomes the shortcomings of existing rubber powder or SBS modified asphalt in terms of high-temperature viscosity, long-term storage stability and low-temperature crack resistance, so that the asphalt has high viscosity, high stability and low-temperature toughness, thereby improving the performance and service life of the asphalt.

[0007] To achieve the above objectives, a first aspect of the present invention provides a method for preparing high-viscosity, high-elasticity modified asphalt, the method comprising: (1) Desulfurize the waste tire powder until the degree of crosslinking of the desulfurized waste tire powder is reduced to no more than 50% of the degree of crosslinking of the waste tire powder; (2) By weight, 70-85 parts of base asphalt, 5-10 parts of desulfurized waste tire powder, 2-6 parts of linear SBS elastomer, 2-5 parts of aminosilane surface-modified nano-SiO2, 0.5-1.5 parts of polyphosphoric acid, 5-12 parts of extracted aromatic oil and 0.5-1 parts of antioxidant are mixed to obtain high viscosity and high elasticity modified asphalt.

[0008] A second aspect of the present invention provides a modified asphalt prepared by the preparation method described herein.

[0009] The above technical solution overcomes the shortcomings of existing rubber powder or SBS modified asphalt in terms of high-temperature viscosity, long-term storage stability and low-temperature crack resistance. It controls the crosslinking degree of desulfurized waste tire powder to a certain range, and combines it with the composition described in this invention to make asphalt have high viscosity, high stability and low-temperature toughness, thereby improving the performance and service life of asphalt. Detailed Implementation

[0010] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0011] The first aspect of this invention provides a method for preparing high-viscosity, high-elasticity modified asphalt, the method comprising: (1) Desulfurize the waste tire powder until the degree of crosslinking of the desulfurized waste tire powder is reduced to no more than 50% of the degree of crosslinking of the waste tire powder; (2) By weight, 70-85 parts of base asphalt, 5-10 parts of desulfurized waste tire powder, 2-6 parts of linear SBS elastomer, 2-5 parts of aminosilane surface-modified nano-SiO2, 0.5-1.5 parts of polyphosphoric acid, 5-12 parts of extracted aromatic oil and 0.5-1 parts of antioxidant are mixed to obtain high viscosity and high elasticity modified asphalt.

[0012] According to a preferred embodiment of the present invention, the degree of crosslinking of the desulfurized waste tire powder is reduced to no more than 20%-40% of the degree of crosslinking of the waste tire powder.

[0013] According to a preferred embodiment of the present invention, the desulfurization treatment conditions include: contacting waste tire powder with a desulfurizing agent and reacting for 1-3 hours at 160-190°C and 0.5-1.5 MPa.

[0014] According to a preferred embodiment of the present invention, the desulfurizing agent is sodium dimethyl dithiocarbamate.

[0015] According to a preferred embodiment of the present invention, the contact angle of the aminosilane-modified nano-SiO2 is ≥120°.

[0016] According to a preferred embodiment of the present invention, the aminosilane is γ-aminopropyltriethoxysilane.

[0017] According to a preferred embodiment of the present invention, the antioxidant is selected from antioxidant 1010 and / or antioxidant 168.

[0018] According to a preferred embodiment of the present invention, the specific surface area of ​​aminosilane-modified nano-SiO2 is 150-250 m² / g.

[0019] According to a preferred embodiment of the present invention, the average particle size of aminosilane-modified nano-SiO2 is 10-40 nm.

[0020] In this invention, the modified asphalt further contains 0.5-1 parts by weight of zinc oxide, which can improve the UV aging resistance while maintaining high viscosity, high stability and low temperature toughness.

[0021] In this invention, the modified asphalt further contains 0.5-1 parts by weight of maleic anhydride-grafted polyisobutylene, which can improve adhesion properties.

[0022] In this invention, the method for preparing the high-viscosity, high-elasticity modified asphalt includes: (1) Mix the base bitumen, waste rubber powder and extracted aromatic oil and perform the first shearing; (2) After heating, antioxidants and SBS are added to perform a second shearing; (3) After cooling, add aminosilane-modified hydrophobic nano-SiO2 to perform the third shearing; (4) After adding polyphosphoric acid and performing the fourth shear, vacuum degassing is performed to obtain modified asphalt.

[0023] According to a preferred embodiment of the present invention, in step (4), 20%-40% of the total weight of polyphosphoric acid is first added and sheared for 4-15 minutes, and then 60%-80% of the total weight of polyphosphoric acid is added and sheared for 4-15 minutes.

[0024] In step (1), the first shearing conditions include: temperature 145-155℃, shearing rate 4000-5000rpm, and time 15-30min; In step (2), the second shearing conditions include: temperature 175-185℃, shearing rate 3000-4500rpm, and time 30-40min; In step (3), the third shearing conditions include: temperature 165-175℃, shearing rate 3000-4500rpm, and time 10-20min; In step (4), the fourth shearing conditions include: temperature 165-175℃, shearing rate 3000-4500rpm, and time 10-20min.

[0025] A second aspect of the present invention provides a modified asphalt prepared by the preparation method described in the present invention, wherein preferably, the modified asphalt has a Brookfield viscosity at 135°C ≥ 3500 mPa·s and a layer thickness ≤ 0.1 mm after standing at 180°C for 72 h.

[0026] The present invention will be described in detail below through embodiments. In the following embodiments, The degree of crosslinking was determined by the equilibrium swelling method: waste tire powder was swollen in an organic solvent (such as toluene) at 25°C until equilibrium was reached. The mass (or volume) before and after swelling was measured, and the crosslinking density ν_e was calculated according to the Flory–Rehner formula. The crosslinking density of the sample before desulfurization was recorded as ν0, and the crosslinking density of the sample after desulfurization was recorded as ν. The relative degree of crosslinking = (ν / ν0)×100%. The desulfurization treatment conditions of this invention make ν / ν0≤0.5. Contact angle determination of aminosilane-modified nano-SiO2: The nano-SiO2 powder to be tested is pressed into a sheet (or spread and compacted to form a test surface). The static contact angle is determined by droplet method using a contact angle meter at (25±2)℃ with deionized water as the test solution. At least 5 different positions are measured for each sample, and the average value is taken as the contact angle. Asphalt viscosity was tested using a Brookfield rotational viscometer. Before testing, the sample was thoroughly stirred and placed into a special sample cup of the viscometer. The sample was kept at a constant temperature of 135±0.5℃ in an oil bath or an electric thermostat for at least 10 minutes to allow thermal equilibrium. A suitable rotor model and rotation speed (e.g., rotor No. 21, 20 rpm) were selected based on the sample's viscosity range. The measurement was performed according to the instrument manual and current asphalt testing procedures. The stable torque value displayed on the viscometer was read and converted to obtain the Brookfield viscosity at 135℃, expressed in mPa·s. At least 2–3 parallel samples were measured for each formulation, and the average value was taken as the viscosity test result for that modified asphalt. Storage stability tests were conducted using a modified asphalt storage stability testing apparatus, including a constant-temperature aging chamber or oil bath furnace and dedicated storage test tubes (such as aluminum or glass tubes). The prepared homogeneous modified asphalt was heated to a fluid state and then slowly poured into preheated storage test tubes. After filling, the tubes were sealed or tightly capped to prevent excessive air ingress. The test tubes containing the samples were then placed vertically in a constant-temperature chamber at 180±5℃ for 72 hours without disturbance. After storage, the test tubes were removed and allowed to cool naturally to room temperature or in cold water. The test tubes were then cut axially to expose the sample cross-section. The thickness of the upper and lower asphalt layers was measured using calipers or a reading microscope, or the layer thickness of the upper lightweight phase was measured directly. Low-temperature toughness was evaluated using an asphalt ductility test. The testing apparatus consisted of an asphalt ductility tester, including a constant-temperature water bath and a constant-speed tensile mechanism. Modified asphalt was poured into ductility molds according to standard methods. After cooling and demolding, the specimens, along with the molds, were placed in a constant-temperature water bath at 5±0.5℃ for pre-curing for at least 60 minutes to ensure uniform internal and external temperatures. During the test, the specimens were mounted on clamps at both ends of the ductility tester, ensuring the specimen axis was aligned with the tensile direction. Under the conditions of a 5±0.5℃ water bath, the specimens were stretched uniformly at a tensile speed of 5 cm / min until fracture. The distance between the two clamps at the moment of fracture was recorded as the ductility value of the specimen. At least three parallel specimens were tested for each formulation, and the average value was taken as the low-temperature ductility index of that modified asphalt.

[0027] Preparation Example 1 Waste tire rubber powder was reacted with sodium dimethyl dithiocarbamate (3% by mass of waste tire rubber powder) at 160℃ and 1.0MPa for 2 hours to obtain desulfurized waste tire rubber powder (with a crosslinking degree of 40% of that before desulfurization).

[0028] Preparation Example 2 Waste tire rubber powder was reacted with sodium dimethyl dithiocarbamate (3% by mass of waste tire rubber powder) at 180℃ and 1.0MPa for 3 hours to obtain desulfurized waste tire rubber powder (with a crosslinking degree of 30% of that before desulfurization).

[0029] Example 1 By weight of raw materials: 70 parts of base asphalt; 10 parts of desulfurized waste tire rubber powder (crosslinking degree of 40% before desulfurization); 5 parts of linear SBS; 3 parts of aminosilane surface-modified nano-SiO2 (contact angle of 128°); 0.8 parts of polyphosphoric acid; 11.2 parts of extracted aromatic oil; 0.5 parts of antioxidant 1010 or a mixture of antioxidant 1010 and antioxidant in a mass ratio of 1:1.

[0030] (1) Mix the base asphalt, waste rubber powder and extracted aromatic oil, heat to 150℃, and shear at 4500r / min for 20min; (2) After heating to 180℃, add antioxidant and SBS, and shear at 4000r / min for 30min; (3) Cool down to 170℃, add γ-aminopropyltriethoxysilane-modified hydrophobic nano-SiO2 and shear at 4000r / min for 10min; (4) Add polyphosphoric acid at 170℃, shear at 4000r / min for 10min each time, and finally at 170℃. The modified asphalt was obtained by vacuum degassing at 0.08 MPa for 5 minutes and then cooling.

[0031] Example 2 By weight of raw materials: 70 parts of base asphalt; 10 parts of desulfurized waste tire rubber powder (crosslinking degree is 30% of that before desulfurization); 5 parts of linear SBS; 2.8 parts of aminosilane surface-modified nano-SiO2 (contact angle is 128°); 0.8 parts of polyphosphoric acid; 11.2 parts of extracted aromatic oil; 0.5 parts of antioxidant 1010 or a mixture of antioxidant 1010 and antioxidant in a mass ratio of 1:1.

[0032] (1) Mix the base asphalt, waste rubber powder and extracted aromatic oil, heat to 150℃, and shear at 4500r / min for 20min; (2) After heating to 180℃, add antioxidant and SBS, and shear at 4000r / min for 30min; (3) Cool down to 170℃, add γ-aminopropyltriethoxysilane-modified hydrophobic nano-SiO2 and shear at 4000r / min for 10min; (4) Add polyphosphoric acid in two portions (mass ratio 30%:70%) at 170℃, shearing for 10 min each time at 4000 r / min, and finally at 170℃. The modified asphalt was obtained by vacuum degassing at 0.08 MPa for 5 minutes and then cooling.

[0033] Example 3 By weight of raw materials: 70 parts base asphalt; 10 parts desulfurized waste tire rubber powder (crosslinking degree is 30% of that before desulfurization); 5 parts linear SBS; 3 parts aminosilane surface-modified nano SiO2 (contact angle is 128°); 0.8 parts polyphosphoric acid; 10.7 parts extracted aromatic oil; 0.5 parts antioxidant 1010 or a mixture of antioxidant 1010 and antioxidant in a 1:1 mass ratio; 0.8 parts zinc oxide.

[0034] (1) Mix the base asphalt, waste rubber powder and extracted aromatic oil, heat to 150℃, and shear at 4500r / min for 20min; (2) After heating to 180℃, add antioxidant and SBS, and shear at 4000r / min for 30min; (3) Cool down to 170℃, add zinc oxide and γ-aminopropyltriethoxysilane surface-modified hydrophobic nano SiO2 and shear at 4000r / min for 10min; (4) Add polyphosphoric acid at 170℃, shear at 4000r / min for 10min each time, and finally at 170℃. The modified asphalt was obtained by vacuum degassing at 0.08 MPa for 5 minutes and then cooling.

[0035] Example 4 By weight of raw materials: 70 parts base asphalt; 10 parts desulfurized waste tire rubber powder (crosslinking degree is 30% of that before desulfurization); 5 parts linear SBS; 3 parts aminosilane surface-modified nano-SiO2 (contact angle is 128°); 0.8 parts polyphosphoric acid; 10.7 parts extracted aromatic oil; 0.5 parts antioxidant 1010 or a mixture of antioxidant 1010 and antioxidant in a 1:1 mass ratio; 0.5 parts zinc oxide; 1 part maleic anhydride grafted polyisobutylene.

[0036] (1) Mix the base asphalt, waste rubber powder and extracted aromatic oil, heat to 150℃, and shear at 4500r / min for 20min; (2) After heating to 180℃, add antioxidant and SBS, and shear at 4000r / min for 30min; (3) Cool down to 170℃, add zinc oxide, maleic anhydride grafted polyisobutylene and γ-aminopropyltriethoxysilane surface-modified hydrophobic nano SiO2 and shear at 4000r / min for 10min. (4) Add polyphosphoric acid at 170℃, shear at 4000r / min for 10min each time, and finally at 170℃. The modified asphalt was obtained by vacuum degassing at 0.08 MPa for 5 minutes and then cooling.

[0037] Example 5 The method is the same as in Example 1, except that the degree of crosslinking of the desulfurized waste tire rubber powder is 48% of that before desulfurization, and the other conditions are the same as in Example 1.

[0038] Comparative Example 1 Compared with Example 1, the difference is that in step (4), polyphosphoric acid is not added, while other conditions remain unchanged.

[0039] Comparative Example 2 Compared with Example 1, the difference is that in step (3), the aminosilane-modified nano-SiO2 is replaced with an equal amount of unmodified SiO2, while other conditions remain unchanged.

[0040] Comparative Example 3 Compared with Example 1, the difference is that undesulfurized 80-mesh waste tire rubber powder is used instead of the desulfurized waste tire rubber powder in Example 1, while all other conditions remain unchanged.

[0041] Comparative Example 4 The method is the same as in Example 1, except that the degree of crosslinking of the desulfurized waste tire rubber powder is 60% of that before desulfurization, and the other conditions are the same as in Example 1.

[0042] Table 1 shows the performance test results of Examples 1-5 and Comparative Examples 1-4.

[0043] Table 1

[0044] The results of Comparative Example 1 in the table above show that the high-temperature viscosity and storage stability decreased significantly without the addition of PPA.

[0045] Comparative Example 2 illustrates that surface hydrophobicity of SiO2 is key to suppressing agglomeration and stratification.

[0046] Comparative Example 2 illustrates the importance of desulfurization of rubber powder in improving compatibility and aging resistance.

[0047] As can be seen from the above embodiments and comparative examples, the three key technologies of hydrophobic nano-SiO2, polyphosphoric acid addition and addition method, and desulfurized rubber powder work synergistically to achieve a balance between high-temperature viscosity improvement, long-term storage stability and low-temperature toughness. Their combined characteristics are inseparable, which fully demonstrates the technical advancement and practical value of the present invention.

[0048] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing high-viscosity, high-elasticity modified asphalt, characterized in that, The method includes: (1) Desulfurize the waste tire powder until the degree of crosslinking of the desulfurized waste tire powder is reduced to no more than 50% of the degree of crosslinking of the waste tire powder; (2) By weight, 70-85 parts of base asphalt, 5-10 parts of desulfurized waste tire powder, 2-6 parts of linear SBS elastomer, 2-5 parts of aminosilane surface-modified nano-SiO2, 0.5-1.5 parts of polyphosphoric acid, 5-12 parts of extracted aromatic oil and 0.5-1 parts of antioxidant are mixed to obtain high viscosity and high elasticity modified asphalt.

2. The preparation method according to claim 1, wherein, The crosslinking degree of desulfurized waste tire powder is reduced to no more than 20%-40% of the total crosslinking degree of waste tire powder; and / or The desulfurization treatment conditions include: contacting waste tire powder with desulfurizing agent and reacting at 160-190℃ and 0.5-1.5MPa for 1-3 hours.

3. The preparation method according to claim 1 or 2, wherein, The desulfurizing agent is sodium dimethyl dithiocarbamate; and / or The desulfurizing agent content accounts for 3-5% of the mass of waste tire rubber powder; and / or Aminosilane-modified nano-SiO2 has a contact angle ≥120°; and / or The aminosilane is γ-aminopropyltriethoxysilane; and / or The antioxidant is selected from antioxidant 1010 and / or antioxidant 168.

4. The preparation method according to claim 1 or 2, wherein, The specific surface area of ​​aminosilane-modified nano-SiO2 is 150-250 m² / g; and / or The average particle size of aminosilane-modified nano-SiO2 is 10-40 nm.

5. The preparation method according to claim 1 or 2, wherein... The modified bitumen also contains 0.5-1 parts zinc oxide by weight.

6. The preparation method according to claim 1 or 2, wherein, The modified bitumen also contains 0.5-1 part maleic anhydride-grafted polyisobutylene.

7. The preparation method according to claim 1 or 2, characterized in that, The method includes: (1) Mix the base asphalt, waste rubber powder and extracted aromatic oil and perform the first shearing; (2) After heating, antioxidants and SBS are added to perform a second shearing; (3) After cooling, add aminosilane-modified hydrophobic nano-SiO2 to perform the third shearing; (4) After adding polyphosphoric acid and performing the fourth shear, vacuum degassing is performed to obtain modified asphalt.

8. The preparation method according to claim 7, wherein, In step (4), first add 20%-40% of the total weight of polyphosphoric acid and shear for 4-15 minutes, then add 60%-80% of the total weight of polyphosphoric acid and shear for 4-15 minutes.

9. The preparation method according to claim 7, wherein, In step (1), the first shearing conditions include: temperature 145-155℃, shearing rate 4000-5000rpm, and time 15-30min; In step (2), the second shearing conditions include: temperature 175-185℃, shearing rate 3000-4500rpm, and time 30-40min; In step (3), the third shearing conditions include: temperature 165-175℃, shearing rate 3000-4500rpm, and time 10-20min; In step (4), the fourth shearing conditions include: temperature 165-175℃, shearing rate 3000-4500rpm, and time 10-20min.

10. Modified asphalt prepared by the preparation method according to any one of claims 1-9; preferably, the modified asphalt has a Brookfield viscosity at 135°C ≥ 3500 mPa·s, and a layer thickness ≤ 0.1 mm after standing at 180°C for 72 h.

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