Envelhecimento asfáltico: estudo comparativo de ensaios mecânicos, reológicos e de adesividade de diferentes porções do revestimento

Abstract

Asphalt aging is one of the main mechanisms responsible for the degradation of asphalt pavement performance, being associated with physicochemical processes that promote the hardening of the binder, loss of flexibility in the mix, and reduction of the interaction between binder and aggregate, especially under wet conditions. In this context, the objective of this study was to understand the mechanisms of asphalt coating aging through the evaluation of the mechanical, rheological, and adhesion properties of the upper, lower, and total portions of the asphalt coating layer. To achieve this, specimens were extracted from the coating of the CE-060 highway and subjected to mechanical tests such as tensile strength, resilience modulus, and fatigue. Additionally, an intact specimen (about 65 mm) was sectioned into upper (about 32.5 mm) and lower (about 32.5 mm) portions, which were also tested in the same mechanical tests. From these samples, asphalt binders were extracted and recovered from these portions, enabling the performance of rheological tests on complex modulus using a dynamic shear rheometer (DSR) and chemical analysis via Fourier-transform infrared spectroscopy (FTIR). Furthermore, the binder-aggregate interaction was assessed through Binder Bond Strength (BBS) adhesion tests, considering different aggregates and moisture conditions. The results allowed the identification of significant variations in mechanical and rheological properties among the different portions of the coating, highlighting a higher degree of aging in the upper region of the asphalt layer. The FTIR analyses support this finding, as they indicated higher oxidation levels for the binder in the upper portion. Regarding the adhesion tests, the results revealed negative impacts of aging on the binder-aggregate interface strength, especially under wet conditions. Thus, the study contributes to understanding the aging of asphalt pavements, providing technical insights for improving design, materials, and more durable maintenance strategies.