A self-healing material has the inherent ability to partially reverse damage such as crack
formation that might have occurred during its service. Significant evidence exists in the
literature to indicate that asphalt binder is a self-healing material. It is also well known
that healing has a substantial affect on the performance of asphalt mixtures and
consequently on the serviceable life of asphalt pavements. For example, shift factors from
laboratory experimental data to field observed data show that laboratory data underpredict
field observations. There is a need to understand the mechanisms that are
responsible for healing in asphalt binders as well as to develop test methods that can be
used to determine properties related to these mechanisms. This thesis presents details
and findings from a two-part study that addresses each one of these two aspects. In the
first part of this study, a test method based on the use of a Dynamic Shear Rheometer
(DSR) was developed to determine the parameters of characteristic healing function of
asphalt binders. In the second part of this study, Molecular Modeling (MM) techniques
were used to determine the interrelationship between molecular structure, surface free
energy, self diffusivity, and other healing properties of asphalt binders.The healing characteristic equation parameter (Ro) which represents the
instantaneous healing nature of the asphalt binders is analogous to surface energy in
terms of effect on healing in asphalt binders. Ro values for three asphalt binders AAM,
AAD and ABD are calculated and compared with the surface energy values available
from the literature. It was observed that the Ro values are proportional to surface energy
values. Surface energy values for five asphalt binders AAM, AAD, AAB, AAG and AAF
are calculated using MM method based on SHRP representative molecules. These values
were observed to be proportional to the surface energy values from literature. Bulk and
surface diffusion coefficients of asphalt molecules are calculated using MM method.
Parametric analysis was done to determine the effect of chemical structure of asphalt on
its diffusion properties. It was observed that the higher percentage of saturates in the
chemical structure results into higher diffusion coefficients.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2919 |
| Date | 15 May 2009 |
| Creators | Bommavaram, Ramamohan Reddy |
| Contributors | Dallas, Little |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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