Study of Moisture Impact on Asphalt Before and After Oxidation Using Molecular Dynamics Simulations

Abstract

Moisture effects on asphalt before and after oxidative aging are investigated in this paper with the molecular dynamics (MD) simulation method. Density, bulk modulus, and zero shear viscosity changes of unoxidized and oxidized asphalt under different moisture contents are compared. The simulations were conducted at 25°C with 0% and 1%, to 10% moisture inclusion incremented by 2.5%. Simulation results showed that the density, bulk modulus, and zero shear viscosity of oxidized asphalt were higher than those of the unoxidized asphalt before any moisture inclusion. These results indicate that hardening happens in asphalt during oxidation. However, after moisture inclusion, the bulk modulus and the zero shear viscosity of unoxidized and oxidized asphalt decreased with an increase in moisture content. Laboratory validation of zero shear viscosity for the unoxidized asphalt showed a result consistent with MD simulation. The moisture effect on density change was not significant for unoxidized or oxidized asphalt, but the density fluctuations of oxidized asphalt were higher than for the unoxidized asphalt. Moreover, moisture affects the bulk modulus and zero shear viscosity of oxidized asphalt more negatively, compared with the unoxidized asphalt. Specifically, the bulk modulus and zero shear viscosity of oxidized asphalt decreased faster than the unoxidized asphalt with moisture inclusion and became lower than the unoxidized asphalt after 5% moisture inclusion. This result indicates that oxidized asphalt is more susceptible to moisture damage.

Get full access to this article

View all access options for this article.

References

Petersen

J. C.

Chemical Composition of Asphalt as Related to Asphalt Durability: State of the Art. In Transportation Research Record 999, TRB, National Research Council, Washington, D.C., 1984, pp. 13–30.

Greenfield

M. L.

Molecular Modelling and Simulation of Asphaltenes and Bituminous Materials. International Journal of Pavement Engineering, Vol. 12, No. 4, Aug. 2011, pp. 325–341.

Pan

, and Tarefder

R. A.

. Investigation of Asphalt Aging Behavior due to Oxidation Using Molecular Dynamics Simulation. Molecular Simulation, Aug. 2015, pp. 1–12.

Petersen

J. C.

Transportation Research E-Circular E-C140: A Review of the Fundamentals of Asphalt Oxidation: Chemical, Physicochemical, Physical Property, and Durability Relationships. Transportation Research Board of the National Academies, Washington, D.C., 2009.

, Huang

, Mahmoud

, and Garibaldy

. Effect of Moisture on the Aging Behavior of Asphalt Binder. International Journal of Minerals, Metallurgy, and Materials, Vol. 18, No. 4, 2011, pp. 460–466.

Chindaprasirt

, Hatanaka

, Mishima

, Yuasa

, and Chareerat

. Effects of Binder Strength and Aggregate Size on the Compressive Strength and Void Ratio of Porous Concrete. International Journal of Minerals, Metallurgy and Materials, Vol. 16, No. 6, 2009, pp. 714–719.

Leach

A. R.

Molecular Modelling: Principles and Applications. Prentice Hall, Upper Saddle River, N.J., 2001.

Zhang

, and Greenfield

M. L.

. Analyzing Properties of Model Asphalts Using Molecular Simulation. Energy and Fuels, Vol. 21, No. 3, May 2007, pp. 1712–1716.

Greenfield

M. L.

, and Zhang

. Final Report—Developing Model Asphalt Systems Using Molecular Simulation. Transportation Center, University of Rhode Island, Kingston, 2009.

10.

D. D.

, and Greenfield

M. L.

. Chemical Compositions of Improved Model Asphalt Systems for Molecular Simulations. Fuel, Vol. 115, Jan. 2014, pp. 347–356.

11.

Tarefder

R. A.

, and Arisa

. Molecular Dynamic Simulations for Determining Change in Thermodynamic Properties of Asphaltene and Resin Because of Aging. Energy and Fuels, Vol. 25, No. 5, May 2011, pp. 2211–2222.

12.

Pan

, Lu

, and Lloyd

. Quantum-Chemistry Study of Asphalt Oxidative Aging: An XPS-Aided Analysis. Industrial and Engineering Chemistry Research, Vol. 51, No. 23, 2012, pp. 7957–7966.

13.

Corbett

L. W.

Composition of Asphalt Based on Generic Fractionation, Using Solvent Deasphaltening, Elution-Adsorption Chromatography, and Densimetric Characterization. Analytical Chemistry, Vol. 41, No. 4, 1969, pp. 576–579.

14.

Petersen

J. C.

, and Glaser

. Asphalt Oxidation Mechanisms and the Role of Oxidation Products on Age Hardening Revisited. Road Materials and Pavement Design, Vol. 12, No. 4, 2011, pp. 795–819.

15.

MOPAC 2012 Software Manual. Stewart Computational Chemistry, Colorado Springs, Colo., 2012.

16.

Jones

D. R.

SHRP Materials Reference Library: Asphalt Cements: A Concise Data Compilation, Vol. 1, TRB, National Research Council, Washington, D.C., 1993.

17.

Fried

J. R.

Chapter 4, Computational Parameters. In Physical Properties of Polymers Handbook ( Mark

J. E.

, ed.), Springer, New York, pp. 59–65.

18.

Tildesley

D. J.

, and Allen

M. P.

. Computer Simulation of Liquids. Clarendon, Oxford, United Kingdom, 1987.

19.

De Visscher

, Soenen

, Vanelstraete

, and Redelius

. A Comparison of the Zero Shear Viscosity from Oscillation Tests and the Repeated Creep Test. In Proceedings of Euroasphalt and Eurobitume Congress, Vienna, Austria, May 2014, 2004, pp. 1501–1513.

20.

Gordon

Influence of Simulation Details on Thermodynamic and Transport Properties in Molecular Dynamics of Fully Flexible Molecular Models. Molecular Simulation, Vol. 29, No. 8, Aug. 2003, pp. 479–487.

21.

Biro

, Gandhi

, and Amirkhanian

. Determination of Zero Shear Viscosity of Warm Asphalt Binders. Construction and Building Materials, Vol. 23, No. 5, 2009, pp. 2080–2086.

22.

Giuliani

, Merusi

, and Antunes

. Creep Flow Behavior of Asphalt Rubber Binder—The Zero Shear Viscosity Analysis. In Proceedings of the Asphalt Rubber 2006 Conference, Palm Springs, Calif., Oct. 25–27, 2006.