Contribution of Rubber Modified Asphalt to Emission and Odors Tracing: Experimental and Modelling Investigation

Abstract

Rubber modified asphalt (RMA) is widely used in infrastructure due to its superior performance; however, its emissions pose environmental and health risks, particularly in enclosed or densely populated areas. This study used emission kinetics, odor assessment, and health risk analysis methods to evaluate the emission characteristics and risks assessment of different types of RMA and its extracted crumb rubber, and reveal the contributions of crumb rubber to RMA emissions. Results revealed that for RMA, macroscopic emission kinetics of H₂S and volatile organic compounds (VOCs) emissions from RMA followed a bi-exponential function, with odor primarily driven by cyclic aromatic hydrocarbons and hydrocarbon derivatives, accounting for >99%. Key odorants identified were octanal, benzothiazole, and 4-methyl-dibenzothiophene. 4-methyl-dibenzothiophene has been identified as a key target for controlling odor and health risks throughout the entire RMA lifecycle. Benzothiazole, decanal, and octanal are found to be characteristic odor contributors of crumb rubber to RMA. Odor assessment analysis confirmed crumb rubber was the major VOCs source in early emission stages. This study provides data-driven guidance for tracking odor emission sources, developing low-emission RMA materials, supporting sustainable infrastructure practices, and improving occupational health standards.