Evaluation of the fatigue performance of fine aggregate matrices prepared with reclaimed asphalt pavements and shale oil residue

• Ano de defesa: 2017
• Autor(a) principal: Klug, Andrise Buchweitz
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Dano contínuo em meio viscoelástico (VECD); Fine aggregate matrices; Matrizes de agregado fino; Misturas asfálticas fresadas; Reclaimed asphalt pavements; Resíduo de óleo de xisto; Shale oil residue; Viscoelastic continuum damage theory (VECD)
• Link de acesso: http://www.teses.usp.br/teses/disponiveis/18/18143/tde-19022018-112755/

The incorporation of recycled asphalt pavements (RAP) in the production of new asphalt mixtures is a useful alternative to the use of virgin materials, leading to economic and environmental savings. Pavement recycling created a sustainable cycle of reuse of nonrenewable natural resources, reducing the demand for new mineral aggregate and binder. However, the addition of RAP, especially at higher percentages, increases the stiffness of the asphalt mixture, because of the high stiffness of the aged binder. High stiffness makes the asphalt mixtures more prone to fatigue cracking. In order to overcome such limitation and allow the incorporation of higher percentages of RAP, soften binders or rejuvenating agents are added to the mixture. The former act to reduce the high stiffness of the aged binder and the latter act to restore the aged binder properties to those required by the binder specifications. The shale oil residue is one of the most used rejuvenating agents in Brazil, and, according to the literature, its performance is comparable to other commercial rejuvenating agents, with the advantage of presenting higher rejuvenating potential, what is due to its higher aromaticity. The fatigue cracking process starts as micro cracks in the fine aggregate matrix (FAM) of the full asphalt mixture. One approach to investigate the fatigue process of the asphalt mixtures is based on the viscoelastic continuum damage theory (VECD), in which the process of micro cracking of a material can be represented by internal state variables associated with the reduction of the material integrity. In this study, tests on FAM samples were performed in order to evaluate the fatigue performance, and the results were analyzed by means of the VECD theory. The objective of this research was to evaluate the fatigue performance of FAMs produced with three RAP contents (20, 40 and 100%), two binders of different performance grades (PG 64-22 and PG 58-16), and the combination of new binder (PG 64-22) and rejuvenating agent (shale oil residue) at different binder/agent rates (100/0, 50/50 and 0/100). Out of the FAMs prepared with RAP, two presented fatigue performance superior to the control mixture (compounded with only new materials): the FAM prepared with 40% of RAP and PG 64-22 and the FAM prepared with 20% of RAP and PG 58-16. The shale oil residue did not play its role of rejuvenating the aged binder for most cases, probably because of the low diffusion rate of the material into the aged binder.