Asphalt bound mixtures have been put to diverse uses. The complicated nature of
the material and the demanding conditions under which it is used preclude complete
solutions to questions on load bearing capability under field conditions. In proportion
to the quantity of its usage and in acknowledgment of modeling complexity, the
material has been interrogated by many researchers using a variety of mechanical
tests, and a plethora of linear viscoelastic models have been developed. Most models
are intended to account for specific classes of problems.
This work addresses the conspicuous absence of systematic documentation of
normal forces generated as a result of shear. The normal force generated during simple
shear is a clear indication of the nonlinear nature of the material. The effect of fillers
(hydrated lime and limestone), air voids, aggregate gradation, asphalt source and step
loading on normal force generation during torsion is experimentally investigated.
Based on experimental evidence, a non-linear thermomechanical model for sandasphalt
mixtures based on the idea of multiple natural configurations is developed.
The model accounts for the fact that the mixture has a natural configuration (stressfree
configuration) which evolves as it is subjected to loads. Assumptions are made
regarding the manner in which the material stores and dissipates energy. A key assumption is that among the various constitutive relations possible, the one that is
chosen is the one that maximizes the rate of entropy production. The model that is
developed accounts for the anisotropic nature of the response.
The experimental results show that asphalt bound mixtures generate significant
normal forces even at low rotation rates. The source of asphalt, aggregate gradation,
fillers and air voids have a pronounced effect on normal stress generation. The model
is corroborated against data from torsion experiments.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1822 |
| Date | 02 June 2009 |
| Creators | Ravindran, Parag |
| Contributors | Rajagopal, Kumbakonam R. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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