Avaliação do envelhecimento e rejuvenescimento de ligantes asfálticos.

Abstract

The aging and rejuvenation of two neat asphalt binders were evaluated in this study.Both binders are from an experimental section that was built with dense hot asphalt mixtures of the two binders, with 4 cm thick. The binders were extracted and recovered from the samples collected from the experimental sections at different times (T = 0, 12, 24, 36 and 108 months after the pavement construction). In the laboratory, the virgin binders were aged using RTFOT, PAV 20h, PAV 60h and SUNTEST. Rheological frequency sweep tests were carried out, as well as the analysis of the parameters G*c, ωc, R and GR. In addition, MSCR and LAS tests were carried out to evaluated the resistance to permanent deformation and to fatigue, respectively, of both binders at different levels of aging and rejuvenation. The SARA fraction, GPC, FTIR and NMR tests were performed to evaluate the chemical changes resulting from laboratory and field aging. The results show that the SUNTEST aging was the most severe, showing the importance of UV radiation in the aging process of asphalt binders. In addition, photochemical aging causes different chemical reactions in the asphalt binders when compared to thermo oxidative aging, with different impact on chemical fractions of the two binders evaluated. In the field, binders continued to age over time, resulting in chemical and performance changes in asphalt binders. The comparison between laboratory and field aging showed that aging in the field (after 36 months) was more severe than the PAV 20h, and the results were closer to PAV 60h, for both binders.The use of pine-based rejuvenating agent with 2%, 4% and 6% content, showed that the AR allowed to recover most of the properties of the aged binders with 4% of AR.However, rejuvenation follows a different trend from aging, showing that AR acts differently on the viscoelastic properties of aged binders. In addition, the AR dosage evaluation using different parameters showed that the dosage only through binder's linear viscoelastic properties may not be sufficient to guarantee the final performance of the recycled mixtures.

Dose Methodology and Rejuvenating Effect of a Plant-Based Biobinder in Aged Asphalt Binders

“…Then, three successive PAV tests were carried out, that is, the test time was increased from 20 (24) to 60 h: this procedure was named PAV60H in this study. This severe condition was chosen to better simulate the typical field conditions found in Brazil (25). PAV60H simulated in a laboratory the aging period for between 8 and 10 years of service in the field.…”