Micromechanical and Chemical Characterization of Foamed Warm-Mix Asphalt Aging

Abstract

This study evaluates the effects of aging on the micromechanical and chemical properties of foamed warm-mix asphalt (WMA) and hot-mix asphalt (HMA) materials. Two asphalt binders were considered. Atomic force microscopy (AFM) was used to examine the micromechanical and adhesion properties of the asphalt binders considered at different aging conditions. In addition, Fourier-transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) techniques were used to identify and quantify the changes in the chemical composition of different asphalt binders due to aging. The results of the AFM tests indicated that the reduced modulus values of the asphalt binders increased with the aging of these binders, while the bonding energy decreased. In addition, the results of the AFM, FTIR, and GPC tests suggested that the WMA binders will experience equal or less aging over the service life of a pavement structure as compared to HMA binders. Good correlations were obtained between the micromechanical and adhesion properties of the considered asphalt binders measured using the AFM and their chemical properties obtained using the GPC and FTIR tests.