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    Dynamic-Mechanic Analysis and Rheological Modelling of Waste Face Mask Modified Bitumen
    (2024) Özdemir, Ahmet Münir; Yalçın, Erkut; Yılmaz, Mehmet; Kök, Baha Vural
    Due to the Covid-19 global pandemic, the use of face masks has increased considerably in recent years. Used face masks are released into our environment and become a severe environmental threat. Therefore, researchers have focused on the recycling of waste face masks. Recently, studies have been carried out on the use of waste face masks as additives in bituminous materials, but a detailed rheological characterization has not been made. In this study, modified bitumens were obtained by adding 1%, 1.5%, 2%, 2.5%, and 3% waste face mask (WFM). Subsequently, frequency sweep test was performed on modified bitumen samples through a Dynamic Shear Rheometer (DSR). Thus, the viscoelastic behavior of WFM modified bitumen was investigated at different temperatures and loading rates. Performance analysis was conducted with rheological master curves, which were characterized according to analytical and mechanistic models. In this study, rheological evaluations were performed according to the Christensen-Anderson (CA) Model, Christensen-Anderson-Marasteanu (CAM) Model, Sigmoidal Model (SM), and finally, the mechanistic Huet-Sayegh Model (HSM). According to the results, it was determined that WFM significantly increased the rutting resistance of bitumen and performed better at low and high loading rates than the pure bitumen at each WFM ratio.
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    Integrating experimental and atomistic insights into the rejuvenation of aged binder using bio-based rejuvenators
    (Elsevier Ltd, 2026) Kurban, Mustafa; Furtana-Yalcin, Beyza; Yílmaz, Mehmet; Akpinar, Sinan; Kök, Baha Vural; Hekim, Seda Surucu; Ozdemir, Ahmet Munir
    This study integrates experimental and computational methods to evaluate the rejuvenation performance of an aged asphalt binder using two novel bio-based additives, 1T and 2T. The aged binder, sourced from reclaimed asphalt pavement (RAP), was modified with 25 wt% of each rejuvenator (denoted as 1T25 and 2T25, respectively). SARA (Saturates, Aromatics, Resins, Asphaltenes) fractionation and colloidal indices were used to assess compositional recovery. Both additives increased aromatic and resin contents while reducing asphaltenes. The 2T-modified binder achieved the highest colloidal stability (Ic = 0.29) and the most pronounced improvement in stability indicators (CI and Ic) among the tested systems. Complementary molecular dynamics (MD) simulations using the COMPASSII force field modeled the structural and thermodynamic behavior of RAP and rejuvenated systems. The 2T25 system exhibited higher density and more compact molecular packing, suggesting stronger cohesive organization and reduced free volume, whereas 1T25 showed greater molecular spacing and flexibility. RDF analysis and converged thermodynamic/structural trajectories (energy, temperature, cell length, and density stabilization) further supported rejuvenator-dependent rearrangement of packing during equilibration. Overall, MD acts as a mechanistic bridge that interprets experimental SARA/CI/Ic trends and supports design-oriented development of sustainable rejuvenators. © 2026 The Author(s).