Chemical Characterization of Recycling Agents

Abstract

Modification of aged binders by the use of recycling agents is significantly influenced by the chemical compositions of these agents. Despite the widespread use of recycling agents, the effect of their chemical properties on the modification process of aged binders cannot be fully found by referencing the reported studies. Recently, the National Center for Asphalt Technology (NCAT) categorized the recycling agents in five main groups. This paper addresses the chemical characteristics of recycling agents in each group by employing saturate, aromatic, resin, and asphaltene (SARA) analysis, Fourier-transform infrared spectroscopy (FT-IR), and elemental analysis. The test results and analyses revealed that the aromatic extracts were similar in chemical composition and bond with virgin unmodified binders. In addition, the results showed that the chemical nature of triglycerides/fatty acids and tall oils might increase the moisture susceptibility and accelerate the degradation of the asphalt binder. The SARA analysis indicated that the compatibility between paraffinic and naphthenic oils with the binder might be a concern; however, the level of oxygen content was low, and these agents did not contain chemical bonds sensitive to moisture and aging.