Three different percentages of carbon nanotubes (CNTs) (0.1%, 0.5%, and 1% by mass of asphalt
cement) were used to modify conventional asphalt cement (60/70) in this study. Mechanical
properties of modified asphalt cement and mixture were evaluated. Penetration grade, kinematic
viscosity, softening point and dynamic shear rheometer test were measured to evaluate physical
properties of modified asphalt cement. The results exhibited that modifying asphalt cement with
CNTs decreased its penetration and increased its kinematic viscosity and softening point. Rutting
parameter increased with CNTs at the given temperature for both unaged and RTFOT-aged
samples. Marshall stability tests, low temperature cracking tests, indirect tensile tests and
wheel tracking tests were conducted to assess the mechanical performance of modified hot
asphalt mixture. The Marshall stability increased with CNTs but no significant difference at 0.5
and 1.0 wt%, while Marshall flow decreased with CNTs. The results of wheel tracking test showed
that rut depth decreased by 45% upon adding 0.5% CNTs by weight of asphalt cement; also, this
percentage of CNTs endowed improvement in low temperature cracking and indirect tensile
strength of the asphalt concrete. This study underlines that adding CNTs into asphalt cement
enhances the performance of asphalt concrete pavement in both hot and cold weather, which in
turn prolongs the pavement’s service life and saves maintenance expenses. |
