Avaliação dos efeitos da temperatura, radiação UV e umidade nas propriedades de ligantes e misturas asfálticas.

Abstract

The aging of asphalt binders is a complex phenomenon that involves physical, chemical, and rheological changes in these materials, directly associated with pavement deterioration mechanisms and a reduction in the performance of asphalt mixtures over time. Thermaloxidative aging of binders is extensively studied following current standards, while photooxidative aging is not standardized, and moisture is rarely considered. Furthermore, the behavior of asphalt mixtures aged by ultraviolet (UV) radiation remains unknown, particularly when combined with moisture, which is a highly relevant factor, as the detrimental effect of water can lead to premature degradation. In this context, this research evaluated the chemical and rheological behavior of the binders and the mechanical behavior of the corresponding asphalt mixtures, subjected to different aging protocols, aiming to infer their compatibility with real field conditions. The binders were initially aged in the short term through the Rolling Thin Film Oven Test (RTFO) and then subjected to long-term aging using different aging inducers, such as heat, oxygen, UV radiation, and moisture. The asphalt mixtures were aged using ShortTerm Oven Ageing (STOA) followed by Long-Term Oven Aging (LTOA), adapted based on the same variables adopted for the binders. The results demonstrated that different combinations of aging processes led to distinct chemical changes, with thermal and photochemical aging following different reaction mechanisms. The dynamic shear modulus (G*) of the binder significantly increased after aging, with the RTFO+OVEN aging being the most influential, which was consistent with the findings for the mixture. Aging also resulted in a reduction in fatigue life at high levels of deformation. As anticipated, permanent deformations decreased after aging. The effects of UV radiation were not as pronounced as expected and may have been influenced by the temperature used in the chamber. The applied stimuli accelerated the aging process of binders, highlighting that UV radiation and moisture should not be overlooked in laboratory aging simulations. Furthermore, good correlations in behavior were observed between the binders and asphalt mixtures, particularly with the OVEN protocol, as it showed compatibility with the FIELD6MONTHS protocol.