Study on eco-friendly zeolite hydrophobic modified asphalt: an effective VOCs-inhibiting additive in sustainable pavement engineering.

This study investigates hydrophobic modification of natural zeolite and its use in asphalt. It aims to improve environmental performance and rheological properties. Natural zeolite was sequentially treated through high-temperature calcination, followed by acid and alkali activation, and subsequently modified with octadecylamine (C18) or trimethylchlorosilane (OM) to enhance its hydrophobicity and adsorption capacity. Microscopic characterizations, including thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) analysis, and contact angle (CA) measurements, confirmed improvements in structural stability and surface hydrophobicity of the modified zeolites. When incorporated into asphalt, the modified zeolite, particularly acid-modified zeolite (ACM)-C18, significantly reduced emissions of volatile organic compounds (VOCs), carbon monoxide (CO), nitric oxide (NO), and hydrogen sulfide (H2S), achieving total pollutant inhibition rates up to 67%. Rheological testing indicated that the addition of modified zeolite improved the stiffness and high-temperature deformation resistance of asphalt, without compromising fatigue performance. These findings highlight the potential of hydrophobically modified zeolite as an effective VOCs-inhibiting additive in sustainable pavement engineering.