Studies on asphalt bitumen modified with carbon nanotubes
Barrera, Enrique V
Doctor of Philosophy
This dissertation studies the viscoelastic mechanical response of asphalt bitumen modified with carbon nanotubes (CNT), and investigates the response of the the CNT- modified bitumen on directed microwave radiation. The first part of this dissertation is aimed at developing an understanding of the viscoelastic mechanical response of asphalt bitumen-CNT composites. Dynamic mechanical analysis experiments were designed to investigate the effect on viscoelastic behavior, including shear storage and loss moduli, the damping coefficient, stress relaxation moduli, and the multiple stress creep recovery (MSCR) behavior of the composites. Frequency scans show that the shear storage modulus, the shear loss modulus, and the stress relaxation modulus all increase with CNT loading, and increase as the test frequency increases. Additionally, the viscoelastic studies demonstrate asphalt bitumen becomes more elastic with an increase in CNT loading. CNTs improve cross-linking between the polymeric chains in the bitumen system. An industry standard penetration test reveals that the penetration index decreases with CNT loading. Multiple stress creep recovery (MSCR) analyses show that, with increasing CNT loading, strain recovery increases and the non-recoverable compliance decreases. The second part of this dissertation investigates the thermal response of asphalt bitumen-CNT composites to directed microwave radiation. The temperature of the composites increases with exposure time. The temperature of the composites also increases with CNT loading, and with an increase in the power of the microwaves.
asphalt; bitumen; carbon nanotubes;