Microscopic Mechanism of Asphalt Mixture Reinforced by Polyurethane and Silane Coupling Agent: A Molecular Dynamics Simulation-Based Study
Abstract
:1. Introduction
2. Materials and Methods
2.1. Materials
2.2. Molecular Dynamics Simulation
2.3. Micro Model Establishment
2.3.1. Asphalt Molecular Model
2.3.2. PU Molecular Model
2.3.3. Establishment and Verification of Asphalt and the PU-Modified Asphalt Model
2.3.4. SCA Molecular Model
2.3.5. Establishment of an Aggregate Model with Grafting SCAs and a Layer Model
2.4. Molecular Dynamics Calculation
2.4.1. Micro-Viscosity
2.4.2. Radial Distribution Function
2.4.3. Adhesion Works at the Interface
2.4.4. Depth of Interaction at the Interface
2.4.5. Mean Square Displacement
3. Experiment
4. Results and Discussion
4.1. Selection of PU Content
4.2. Analysis of the Interface Properties
4.2.1. Adhesion Work
4.2.2. Adhesion Depth
4.3. Thermal Stability of the Interface
4.4. Basic Test Performance Analysis
5. Conclusions
- (1)
- At the microscopic level, the micro-viscosity of PU-modified asphalt with different contents and the RDF of PU are analyzed, and it can be seen that when the PU content is 20.8%, the compatibility between PU and asphalt and the micro-viscosity of PU-modified asphalt are the best.
- (2)
- The adhesion work, adhesion depth, and thermal stability between PU-modified asphalt and SiO2 grafted with different SCAs were investigated by molecular simulation. It can be seen that the chain length and shape of the SCA, and whether the functional group can react with PU, are important influencing factors. The enhancement effect of KH-570 on the interface is greater than that of KH-550, but due to the reactivity of the amino at the end of KH-550, it is predicted that the interface enhancement effect of KH-550 is the best in the actual application.
- (3)
- Taking the hot mix SBS-modified asphalt mixture as the control group, the properties of the warm mix PU-modified asphalt mixture with or without the SCA were analyzed. The high-temperature and strength performance of the warm mix PU-modified asphalt mixture are better than those of the hot mix SBS-modified asphalt mixture, but the low-temperature performance is slightly lacking, and the water damage resistance cannot meet the requirements of the specification. The two performances of the PU-modified asphalt mixture after adding SCAs on the aggregate are enhanced, and both meet the requirements of the specification.
- (4)
- Comparing the basic performance of PU-modified asphalt with and without SCAs by the macro test, it can be seen that the improvement effect of KH-550 is stronger than that of KH-570. Combined with the conclusion of the molecular simulation, it is concluded that KH-550 chemically reacts with molecules with the isocyanate in PU-modified asphalt, which effectively prolongs the chain length of SCAs and forms a larger cross-linked network between asphalt and aggregate to provide better performance for the mixture. So, KH-550 has better performance in practical applications.
Author Contributions
Funding
Institutional Review Board Statement
Data Availability Statement
Conflicts of Interest
Abbreviations
EG | Ethylene glycol |
PU | Polyurethane |
RDFs | Radial distribution functions |
SCAs | Silane coupling agents |
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Asphalt | 25 °C Penetration/0.1 mm | 15 °C Ductility/cm | Softening Point/°C |
---|---|---|---|
CNOOC 90# | 92.8 | 107 | 46.9 |
25 °C Physical State | Viscosity/(25 °C, MPa·s) | NCO Mass Fraction/% | Density/(25 °C, g·cm−3) |
---|---|---|---|
Brown liquid | 150~250 | 30.2~32.0 | 1.22~1.25 |
25 °C Physical State | Viscosity/(25 °C, MPa·s) | Density/(25 °C, g·cm−3) | Content/% |
---|---|---|---|
Colorless oily liquid | 72 | 1.02 | ≥99 |
Full Chemical Name | Abbreviated Name | 25 °C Physical State | Density/(25 °C, g·cm−3) |
---|---|---|---|
(3-Aminopropyl) triethoxysilane | KH-550 | colorless liquid | 0.95 |
(Trimethoxysilyl) propyl methacrylate | KH-570 | light yellow liquid | 1.05 |
Physical State | Proportion | Tensile Strength/0.1 mm | Hardness | Elongation at Break/% |
---|---|---|---|---|
White particles | 0.93 | 120 | 83 | 345 |
Asphalt Component | Number of Molecules | Mass Fraction/% | |
---|---|---|---|
Asphaltene | Asphaltene-phenol | 3 | 13.3 |
Asphaltene-pyrrole | 3 | ||
Asphaltene-thiophene | 2 | ||
Polar Aromatics | Pyridinohopane | 4 | 31.1 |
Thin-isorenieratane | 7 | ||
Benzobisbenzothiophene | 6 | ||
Quinolinohopane | 4 | ||
Trimethylbenzene-oxane | 7 | ||
Naphthene Aromatics | PHPN | 17 | 37.6 |
DOCHN | 18 | ||
Saturates | Squalene | 7 | 18.0 |
Hopane | 8 |
Asphalt Component | Cohesive Energy Density/(×108 J/m3) | Solubility Parameter /(J/cm3)1/2 | |
---|---|---|---|
Asphaltene | Asphaltene-phenol | 2.78 | 16.685 |
Asphaltene-pyrrole | 2.73 | 16.524 | |
Asphaltene-thiophene | 2.64 | 16.265 | |
Polar Aromatics | Pyridinohopane | 2.66 | 16.323 |
Thin-isorenieratane | 2.79 | 16.724 | |
Benzobisbenzothiophene | 2.86 | 16.934 | |
Quinolinohopane | 2.71 | 16.47 | |
Trimethylbenzene-oxane | 2.73 | 16.55 | |
Naphthene Aromatics | PHPN | 2.80 | 16.761 |
DOCHN | 2.76 | 16.624 | |
Saturates | Squalene | 2.60 | 16.142 |
Hopane | 2.60 | 16.126 | |
Maximum Difference Value | 0.16 | 0.808 |
Number of PU Molecules | PU Content/% | Model Density/(g/cm3) | Measured Density/(g/cm3) | Error /% |
---|---|---|---|---|
0 | 0 | 0.994 | 1.02 | 2.6 |
3 | 10.3 | 1.007 | 1.03 | 2.3 |
4 | 13.3 | 1.014 | 1.04 | 2.6 |
5 | 16 | 1.016 | 1.04 | 2.3 |
6 | 18.7 | 1.017 | 1.04 | 2.3 |
7 | 21.1 | 1.02 | 1.05 | 2.9 |
8 | 23.5 | 1.022 | 1.08 | 5.6 |
9 | 2 | 1.03 | 1.09 | 5.8 |
No. | Full Chemical Name | Abbreviated Name | Chemical Structure | Relative Molecular Mass | Length After Grafting/Å |
---|---|---|---|---|---|
1 | (3-Aminopropyl) triethoxysilane | KH-550 | 221 | 7.353 | |
2 | Vinyltris (b-methoxyethoxy) silane | KH-172 | 280 | 7.090 | |
3 | (Trimethoxysilyl) propyl methacrylate | KH-570 | 248 | 10.71 | |
4 | Aniline methyl triethoxy silane | ND-42 | 269 | 11.37 |
Mass Percentage Through Mesh (mm)/% | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Sieve size/mm | 19 | 16 | 13.2 | 9.5 | 4.75 | 2.36 | 1.18 | 0.6 | 0.3 | 0.15 | 0.075 |
Passing rate/% | 100 | 93.6 | 86.3 | 74.1 | 52.7 | 32.4 | 24.1 | 15.6 | 9.4 | 6.1 | 5.4 |
PU Content /% | 25 °C Penetration/0.1 mm | 15 °C Ductility/cm | Softening Point/°C | 60 °C Dynamic Viscosity/(Pa.s) |
---|---|---|---|---|
5 | 92.8 | 108 | 46.9 | 162 |
10 | 70.5 | 116 | 60.3 | 175 |
15 | 62.3 | 125 | 78.9 | 268 |
20 | 50.2 | 138 | 85.6 | 345 |
25 | 45.3 | 138 | 86.1 | 351 |
No. | Modifier | Modifier Content/% | Aggregate Surface Treatment |
---|---|---|---|
D | SBS | 5% | / |
E | PU | 20% | |
F | KH-550 (1%) | ||
G | KH-570 (1.12%) |
Performance Indexes of Asphalt Mixtures | Unit | Modified Asphalt Mixtures | Specification Requirements | |||||
---|---|---|---|---|---|---|---|---|
D | E | F | G | Maximum Error/% | ||||
High-temperature performance | Stability of the rut | times/mm | 4526 | 6172 | 6285 | 6192 | 4.5 | ≥2400 |
Low-temperature performance | Flexural tensile strength | MPa | 9.2 | 8.29 | 8.65 | 8.46 | 3.6 | / |
Flexural tensile strain | με | 3216 | 3165 | 3379 | 3212 | 6.3 | ≥3000 | |
Strength performance | Marshall stability | kN | 10.3 | 11.5 | 12.8 | 12.3 | 2.1 | ≥8 |
Flow value | mm | 2.68 | 2.26 | 2.16 | 2.19 | 4.5 | ≤4 | |
Water stability | Residual stability of the immersion Marshall test | % | 90.3 | 86.9 | 89.4 | 87.8 | 6.4 | ≥85 |
Residual strength ratio of the freeze–thaw splitting test | % | 85.3 | 78.6 | 84.7 | 82.5 | 5.7 | ≥80 |
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Lin, Z.; Sima, W.; Gao, X.; Liu, Y.; Li, J. Microscopic Mechanism of Asphalt Mixture Reinforced by Polyurethane and Silane Coupling Agent: A Molecular Dynamics Simulation-Based Study. Polymers 2025, 17, 1602. https://doi.org/10.3390/polym17121602
Lin Z, Sima W, Gao X, Liu Y, Li J. Microscopic Mechanism of Asphalt Mixture Reinforced by Polyurethane and Silane Coupling Agent: A Molecular Dynamics Simulation-Based Study. Polymers. 2025; 17(12):1602. https://doi.org/10.3390/polym17121602
Chicago/Turabian StyleLin, Zhi, Weiping Sima, Xi’an Gao, Yu Liu, and Jin Li. 2025. "Microscopic Mechanism of Asphalt Mixture Reinforced by Polyurethane and Silane Coupling Agent: A Molecular Dynamics Simulation-Based Study" Polymers 17, no. 12: 1602. https://doi.org/10.3390/polym17121602
APA StyleLin, Z., Sima, W., Gao, X., Liu, Y., & Li, J. (2025). Microscopic Mechanism of Asphalt Mixture Reinforced by Polyurethane and Silane Coupling Agent: A Molecular Dynamics Simulation-Based Study. Polymers, 17(12), 1602. https://doi.org/10.3390/polym17121602