الفهرس 
Abstract
Nanotechnology Applications in Civil EngineeringOnly 14 pages are availabe for public view
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Abstract
Over the last decades, there have been a variety of modifiers such as synthetic polymers, natural and crumb rubber used to enhance the mechanical and rheological properties of conventional asphalt in order to minimize the possibility of pavement distresses and increase service life of asphalt pavement. Recently, many researchers are interested in studying what nanotechnology can offer in improving characteristics and performance of asphalt pavements. This Study mainly aims at investigating the effect of using multi-wall carbon nanotubes (MWCNTs) as an additive on the rheological properties of asphalt and the mechanical properties of mixtures. First the effect of functionalization on the dispersion quality of MWCNTs was studied. Pristine MWCNTs (P-MWCNTs) were chemically modified using acid functionalization process to introduce carboxylic acid groups onto the surface of MWCNTs. The effect of functionalization on the MWCNTs dispersion quality and the rheological properties of modified asphalt was evaluated. The MWCNTs functionalization yielded negative effects on both the dispersion quality and rheological properties of the asphalt modified with functionalized MWCNTs compared to that modified using P-MWCNTs. The effect of mixing technique (high shear mixer and a manufactured mechanical mixer) on the dispersion quality of MWCNTs with asphalt was also evaluated. Results indicated both mixers yielded similar properties based on the rotational viscosity testing. Finally, P-MWCNTs were then mixed at 120°C with control asphalt at contents of 0.5%, 1.0%, 2.0% and 3.0% by asphalt weight. The classical and rheological properties (using the Superpave testing) of the control and modified asphalts were evaluated at different aging conditions. The mechanical properties of the P-MWCNTs modified mixtures were investigated. The results indicated that the use of MWCNTs as a modifier was helpful in improving the conventional and rheological properties of the modified asphalt and mixture. Generally, the rheological properties of the modified asphalts were found to improve with increasing the percentage of P-MWCNTs. The high failure temperature and rutting resistance of both unaged and rolling thin film oven aged (RTFO) modified asphalts increased with increasing P-MWCNTs percentage and became suitable for the Egyptian climatic conditions as required by the Superpave binder characterization. At a given temperature, the fatigue cracking resistance and low temperature cracking resistance decreased with increasing the P-MWCNTs percentage. For modified asphalt mixtures, with increasing the amount of P-MWCNTs, Marshall stability remarkably increased (up to 77% for the 3.0% CNTs modified mixture) and flow decreased. Addition of CNTs increased the loss of stability (18.29 % for 3.0% CNTs modified mixture compared to 0.85% for the control mixture). For moisture sensitivity results, the increase in the P-MWCNTs yielded an increase in the tensile strength of the dry samples compared to the control mix. The tensile strength ratio (TSR) was increased by 16.6% and 7.40% corresponding to 2.0% and 3.0% CNTs modified mixtures, respectively. The Pavement ME design software was used to predict the field performance of both the conventional and modified asphalt mixes. Results showed that the performance of the modified mix was superior to that of the conventional mix.