Performance Evaluation of Asphalt Binder Modified with Nanomaterials

Abstract

This study explores the optimization of hot mix asphalt (HMA) performance through the incorporation of nano clay (NC) and carbon nano tubes (CNTs) into the asphalt binder. Through a systematic evaluation, the research determines the optimal proportions of these nanomaterials by assessing their impact on crucial asphalt properties, including viscosity, shear modulus, shift angle, stiffness, the slope of the stiffness-time curve, nonrecoverable shear compliance, and percent recoverable strain. The results reveal that an NC content exceeding 0.8% surpasses the Superpave rotational viscosity limit, thereby adversely affecting the workability of the asphalt mixture. Consequently, further testing on NC-modified binder is halted, with the focus redirected to CNTs-modified binder. The optimal CNT content is identified as 1%. At this concentration, the highest rutting parameter ratio (G*/sinδ) is achieved, along with the lowest nonrecoverable shear compliance and highest percent recoverable strain. On the other hand, this CNT content caused a minimal adverse effect from a small increase in rotational viscosity, creep stiffness at low temperature, and fatigue parameter (G*sinδ) at an average service temperature. Additionally, this CNT concentration results in the stiffness-time curve having a steeper slope, indicating less susceptibility to low-temperature cracking. These findings demonstrate that 1% CNTs substantially enhance the rutting and low-temperature cracking resistance without significantly compromising fatigue crack resistance and workability during mixing and compaction. They offer valuable insights into tailoring asphalt binder compositions for enhanced HMA performance. Numerous studies delved into the use of various polymers as additives and revealed inconsistent improvements across the mechanical properties of HMA. In some cases, these additives have even detrimentally affected HMA performance. Conversely, nanomaterials offer a promising avenue for the development of a new generation of asphalt additives. This study undertakes a comprehensive evaluation process, including an assessment of the rheological behavior, fatigue cracks resistance, and rutting resistance to provide a more holistic understanding of the modified binder’s performance. This study yields valuable insights for both the state of the art and/or state of the practice in the field of asphalt technology. The results offer quantitative data on the enhancement of binder performance through nanomaterial utilization, potentially catalyzing further research, influencing industry practices, and fostering the widespread adoption of nanomaterial-modified asphalt binders in pavement construction. This could ultimately lead to safer, more durable, longer-lasting pavements, necessitating reduced maintenance and offering increased cost-effectiveness. This study builds on previous research, refines established methodologies, and proposes modifications to industry standards. Therefore, this study is expected to integrate with or challenge existing knowledge in the realm of the impact of nanomaterials on asphalt binder performance.