Evaluation of Moisture Sorption and Diffusion Characteristics of Asphalt Mastics Using Manual and Automated Gravimetric Sorption Techniques
Publication: Journal of Materials in Civil Engineering
Volume 26, Issue 8
Abstract
One of the most important factors influencing the durability of asphalt mixtures is moisture-induced damage resulting from the presence and the transport of moisture in pavements. Moisture-induced damage is an extremely complicated phenomenon that is not completely understood but believed to be governed by the interaction of moisture with asphalt mix components (mastic and aggregates). The objective of this study was, therefore, to characterize the sorption and diffusion characteristics of asphalt mastic using gravimetric vapor sorption techniques. Moisture transport, in the hygroscopic region, in asphalt mastics was studied using both static and dynamic gravimetric vapor sorption techniques to determine equilibrium moisture uptake and diffusion coefficients as a function of aggregate and filler types. For the 25-mm diameter thin asphalt mastic films and the testing conditions (23°C and 85% relative humidity) considered, the kinetics of moisture uptake obtained were characteristic of Fickian diffusion with a concentration-dependent diffusion coefficient. Equilibrium moisture uptake and diffusion coefficient estimated from the static measurements were comparable and of the same order of magnitude as those from dynamic sorption techniques. Both measurement techniques ranked the mixes similarly, which suggest either method could be used to characterize moisture transport in asphalt mastics. Equilibrium moisture uptake was relatively higher in mixtures containing granite aggregates compared with limestone aggregate. In contrast, the diffusion coefficient of limestone aggregate mastics was higher than granite. Thus, an inversely proportional relationship exists between moisture uptake and diffusivity of the asphalt mastics studied. The results suggest moisture transport is a function of aggregate type and that both equilibrium moisture uptake and diffusion coefficient are useful in studying moisture susceptibility in asphalt mixtures. The effect of mineral filler type on diffusion coefficient was minimal in the mastics containing granite aggregate but relatively high in mastic samples containing limestone aggregates. Diffusion coefficient was found to increase with sample thickness, which was unexpected because diffusion coefficient (in an isotropic material) is considered an intrinsic property that is independent of sample size. The results suggested anisotropic diffusivity can occur in asphalt mastics and could be attributed to factors, including mineralogy, microstructure, air voids, and the tendency of the aggregates to settle at the bottom of asphalt mastic with time. In addition to characterizing moisture transport in asphalt mastics, the results presented in this paper will be useful as inputs for numerical simulation of moisture damage in asphalt mixtures.
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Acknowledgments
The authors acknowledge the assistance of the following Nottingham Transportation Engineering Centre personnel: Martyn Barrett, Richard Blakemore, Nancy Milne, Lawrence Pont, Jonathan Watson, and Michael Winfield for material testing. The funding for this project was provided in part by the U.K. Engineering and Physical Sciences Research Council (EPSRC).
References
AASHTO. (2010). “Standard method of test for specific gravity and absorption of fine aggregate.”, Washington, DC.
AASHTO. (2012). “Bulk specific gravity of compacted hot mix asphalt using saturated surface-dry specimens.”, Washington, DC.
Airey, G. D., and Choi, Y. K. (2002). “State of the art report on moisture sensitivity test methods for bituminous pavement materials.” Road Mater. Pavement Des., 3(4), 355–372.
Airey, G. D., Masad, E., Bhasin, A., Caro, S., and Little, D. (2007). “Asphalt mixture moisture damage assessment combined with surface energy characterization.” Proc., Int. Conf. on Advanced Characterization of Pavement and Soil Engineering, A. Loizos, T. Scarpas and Al-I. L. Qadi, eds., Taylor & Francis, London.
Apeagyei, A. K., Buttlar, W. G., and Dempsey, B. J. (2006). “Moisture damage evaluation of asphalt mixtures using AASHTO T283 and DC(T) fracture test.” Proc., 10th Int. Conf. on Asphalt Pavements, International Society of Asphalt Pavement, Quebec, Canada, 740–751.
Arambula, E., Caro, S., and Masad, E. (2010). “Experimental measurement and numerical simulation of water vapor diffusion through asphalt pavement materials.” J. Mater. Civ. Eng., 588–598.
ASTM. (2005). “Standard test methods for water vapor transmission of materials.”, ASTM International, West Conshohocken, PA.
Cheng, D. X., Little, D. N., Lytton, R. L., and Holste, J. C. (2003). “Moisture damage evaluation of asphalt mixture by considering both moisture diffusion and repeated-load conditions.”, Transportation Research Board, Washington, DC, 42–49.
Comyn, J. (1983). Durability of structural adhesives, A. J. Kinloch, ed., Applied Science Publishers, New York, 84.
Crank, J. (1975). The mathematics of diffusion, 2nd Ed., Oxford University Press, New York, 414.
Curtis, C. W., Lytton, R. L., and Brannan, C. J. (1992). “Influence of aggregate chemistry on the adsorption and desorption of asphalt.”, Transportation Research Board, Washington, DC, 1–9.
EN. (2004). “Test methods for hot mix asphalt—Part 6: Determination of bulk density of bituminous specimens.”, British Standard Institution, London.
EN. (2008). “Tests for mechanical and physical properties of aggregates—Determination of the particle density of filler—Pyknometer method.”, British Standard Institution, London.
Fernando, W. J. N., Low, H. C., and Ahmad, A. L. (2011). “Dependence of the effective diffusion coefficient of moisture with thickness and temperature in convective drying of sliced materials. A study on slices of banana, cassava and pumpkin.” J. Food Eng., 102(4), 310–316.
Fisher, H. L., Faust, H. L., and Walden, G. H. (1922). “Alumina as an absorbent for water in organic combustions.” J. Ind. Eng. Chem., 14(12), 1138.
Henon, F. E., Carbonell, R. G., and DeSimone, J. M. (2002). “Effect of polymer coatings from on water-vapor transport in porous media.” AIChE J., 48(5), 941–952.
Kassem, E. A., Masad, E., Bulut, R., and Lytton, R. L. (2006). “Measurements of moisture suction and diffusion coefficient in hot-mix asphalt and their relationships to moisture damage.”, Transportation Research Board, Washington, DC, 45–54.
Kringos, N., Scarpas, A., and deBondt, A. (2008). “Determination of moisture susceptibility of mastic-stone bond strength and comparison to thermodynamical properties.” J. Assoc. Asphalt Paving Technol., 77, 435–478.
Pereira, M. R., and Yarwood, J. (1996). “ATR-FTIR spectroscopic studies of the structure and permeability of sulfonated poly(ether sulfone) membranes. 2: Water diffusion processes.” J. Chem. Soc., Faraday Trans., 92(15), 2737–2743.
Terrel, R. L. (1994). “Water sensitivity of asphalt-aggregate mixes.”, Strategic Highway Research Program, National Research Council, Washington, DC.
Tutuncu, M. A., and Labuza, T. P. (1996). “Effect of geometry on the effective moisture transfer diffusion coefficient.” J. Food Eng., 30(3–4), 433–447.
Vasconcelos, K. L., Bhasin, A., Little, D. N., and Lytton, R. L. (2011). “Experimental measurement of water diffusion through fine aggregate mixtures.” J. Mater. Civ. Eng., 445–452.
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Published In
Journal of Materials in Civil Engineering
Volume 26 • Issue 8 • August 2014
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Jan 23, 2013
Accepted: Aug 23, 2013
Published online: Aug 27, 2013
Published in print: Aug 1, 2014
Discussion open until: Oct 9, 2014
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