Moisture damage in asphalt mixtures is a complex phenomenon that involves mechanical,
chemical, physical and thermodynamic processes. This damage contributes significantly to the
premature deterioration of asphalt pavements, which leads to extra cost in highway maintenance
and vehicle operations. One key mechanism of how moisture reaches the asphalt-aggregate
interface is by its permeation or diffusion through the asphalt binder or mastic. Different
techniques are available for diffusion coefficient measurement of a wide variety of polymersolvent
systems. For the asphalt-water system studied, the focus is on two techniques: (i) Fourier
Transform Infrared (FTIR)-Attenuated Total Reflectance (ATR) spectrometry and (ii)
Gravimetric Sorption Measurements. In the FTIR-ATR experiments, asphalt binders are under
investigation. Water shows strong absorption in the infrared region and the FTIR-ATR technique
has the ability to monitor both the kinetics of moisture ingress as well as any chemical changes
occurring during the test. The changes in concentration can be directly related to change in the
absorbance measured during the experiment. The hysteresis of water diffusion in asphalt binders
is also monitored through this technique. In the gravimetric sorption experiments, cylindrical
Fine Aggregate Mixtures (FAM) were investigated. The gravimetric techniques, which directly
follow mass change with time, are among the most used techniques probably because of their
simplicity. In this experiment, the Saturated Surface-Dry (SSD) weight of FAM samples at room
temperature and at 100 degrees F is monitored until it reaches the equilibrium. The measurements of: (i)
water uptake and (ii) the diffusion coefficient were made at both temperatures. A dual mode
diffusion model was shown to better represent the diffusion of water through asphalt binders.
The rate of moisture diffusion in asphalt binders was proved to be dependent on the history of exposure of the asphalt binder to the moisture. Moisture uptake and diffusivity of water through
FAM is dependent on the type of aggregate and asphalt binder used to prepare the FAM.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2010-05-7651 |
| Date | 2010 May 1900 |
| Creators | Vasconcelos, Kamilla L. |
| Contributors | Little, Dallas N. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | thesis, text |
| Format | application/pdf |
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