Thermally modified attapulgite as a green functional modifier for VOCs suppression in SBS modified asphalt composites

Abstract

During asphalt binder heating and paving, volatile organic compounds (VOCs) emissions unavoidably pose significant threats to human health and environment. This study investigated the feasibility of utilizing thermally modified attapulgite (TMA) as a green adsorption additive to mitigate VOCs emissions in SBS modified asphalt binder. TG experiments identified critical heat modification temperatures (110 °C, 250 °C, 520 °C, and 690 °C) for attapulgite (ATP) to regulate its physicochemical properties. Structural evolution and surface characteristics were systematically analyzed via XRD, FTIR, BET and Zeta potential techniques, while GC-MS was employed to evaluate VOCs emission behavior of ATP-SBS composite modified asphalt binder under heating conditions. Results show ATP modified at 520 °C (TMA520) achieved the highest VOCs reduction efficiency of 52.7%, attributed to retained surface structure and optimized pores. Furthermore, TMA520 significantly enhanced the high temperature performance of SBS modified asphalt binder. Although interaction with binder is physical, TMA520's high zeta potential ensures uniform dispersion and provides strong electrostatic adsorption for VOCs. Its hierarchical pore structure is crucial: macropores/mesopores capture and transport VOCs, while micropores immobilize them. This work demonstrates an effective approach for utilizing eco-functional minerals in binder, promoting cleaner pavement construction, particularly in ecologically sensitive regions.