Engineering Physical Properties of Asphalt Binders through Nanoclay-Asphalt Interactions

Increasing traffic volumes, heavier loads, higher tire pressures, and performance problems with asphalt concrete mixtures under adverse conditions are leading state highway departments to using modified binders to enhance the physical properties of asphalt mix. This paper reports the advantages of modified nanoclays (NC) as asphalt modifiers. Dynamic mechanical analysis, flexural creep stiffness, and flexural tests were conducted on the NC-asphalt nanocomposite. In addition, Fourier transform infrared (FTIR) testing was conducted to evaluate the nature of the interactions between NC and asphalt. Increasing NC concentration in asphalt enhances temperature susceptibility of asphalt, as well as increasing the complex modulus in addition to decreasing phase angle. FTIR experiments indicate a significant change in SiO vibration from NC, indicating strong nonbonded interactions of SiO tetrahedra with asphalt. These changes in SiO vibrations suggest both distortion in SiO tetrahedra as well as stronger interactions between asphalt and NC. Further, X-ray diffraction (XRD) testing results show intercalation of asphalt in clay galleries indicated by an enlarged d-spacing of up to 43.17 angstrom. The d-spacing decreases with NC content. These experiments suggest that the addition of engineered nanoclays to asphalt has tremendous potential in tailoring the properties of asphalt based on type of application.