| dc.description.abstract | Abstract
This thesis investigates how the mechanical properties of asphalt mixtures change when different amounts of recycled asphalt are added and Dynamic modulus testing value is used to study the effects of adding various quantities of recycled asphalt. The dynamic modulus (E*) is an important parameter that describes how asphalt mixtures respond to different temperatures and loading frequencies, essential for evaluating pavement performance.
The research involved thorough lab testing at the University of Agder using a Universal Testing Machine on asphalt mixture AC11, analyzing levels of RA content at 12.4%, 30%, and 40%. The testing protocol followed the standards outlined in AASHTO T 378-17(2021), ensuring consistency and reliability in the measurements.
By applying the principle of time-temperature superposition, master curves for dynamic modulus were created using sigmoidal modeling. The created master curves show how the material changes as time passes, offering a single equation for E* values in different temperature and frequency ranges.
The study found important connections between dynamic modulus, temperature, and frequency, showing that materials become less rigid at higher temperatures and more pliable at higher frequencies. Analysis comparing dynamic modulus values at varying RA contents revealed greater stiffness and durability at higher RA levels. Significantly, asphalt mixtures with 40% RA showed increased stiffness, suggesting improved performance and sustainability.
Analysis of the shift factor revealed different rheological properties depending on the amount of RA in the specimens, with 40% RA samples showing increased stiffness and resistance to deformation at lower temperatures. Nevertheless, under high temperatures, these samples showed a higher vulnerability to rutting, highlighting the importance of a well-rounded strategy when incorporating RA.
The research highlights the significance of taking into account RA content in asphalt mixes in order to enhance performance and sustainability in road building. Overall, this study adds to the creation of a thorough Master Curve (E*) database for asphalt mixtures containing recycled asphalt, providing important knowledge for pavement engineering.
Further research is needed to study how various types of aggregate and aging periods affect the performance of asphalt mixtures in order to establish reliable design standards for sustainable pavement solutions. | |
