Steric aging analysis of rejuvenated recycled asphalt binders and mixtures during one-year of storage time

• Published in: Construction & building materials 2024-11, Vol.452, p.138916, Article 138916
• Main Authors: Sharma, Ankit, Ransinchung Rongmei Naga, Gondaimei, Kumar, Praveen, Cannone Falchetto, Augusto
• Format: Article
• Language: English
• Subjects: Asphalt pavements; RAP; Recycling; Rejuvenator; Reversible aging; Steric hardening
• ISSN: 0950-0618
• DOI: 10.1016/j.conbuildmat.2024.138916

Steric hardening, a gradual time-dependent phenomenon in asphalt binders, is crucial to study as it influences the long-term performance of recycled asphalt pavements. The type of rejuvenator plays a significant role in mitigating this hardening by restoring the properties of aged binders. However, since the behavior of asphalt as a thin film over aggregates differs from that of bulk binder, it is essential to evaluate steric hardening at both binder and mixture levels. This study investigates the effects of steric hardening in recycled binders and mixtures stored for 12 months at 25°C, focusing on different rejuvenators and their Saturates, Aromatics, Resins, and Asphaltenes (SARA) compositions. Using a 60/70 grade base binder with 40 % Reclaimed Asphalt Pavement (RAP), Rejuvenator B (with 92 % resin content) led to a 44 % increase in stiffness, while Rejuvenator A (rich in saturates) limited hardening to 27 %. The progression of steric hardening followed a polynomial trend over time. The consistent rise in Indirect Tensile Stiffness Modulus (ITSM) across temperatures demonstrated its effectiveness in evaluating long-term hardening effects. These findings provide critical insights into selecting appropriate rejuvenators to control steric hardening and improve the durability of recycled asphalt pavements. •Rejuvenators with high resin content demonstrate pronounced steric hardening effects.•Rejuvenators rich in saturates exhibit reduced susceptibility to steric hardening.•Penetration and Softening Point serve as empirical indicators for steric hardening effects.•Steric hardening's temperature dependency becomes more evident at elevated testing temperatures.