Análise do comportamento reológico e de envelhecimento de ligantes asfálticos contendo nanofibrilas de celulose.

Abstract

The addition of nanoparticles has become a growing topic in scientific research due to their extremely small size, which can serve as an alternative to improve the characteristics of asphalt mixtures, such as stiffness, emission reduction, fatigue resistance, and aging retardation. Among the materials used for modification, cellulose is presented as an alternative, being a natural polymer material derived from abundant sources, as it can be obtained from vegetation waste and bacteria. This study incorporated two types of cellulose nanofibrils (CNF) into the asphalt binder CAP 50/70, at mass ratios of 0.5, 1, 2, and 5%. The developed binder-nanoparticle mixtures were chemically and rheologically evaluated and subjected to different aging procedures including short-term aging simulation (RTFOT), freeze-thaw cycles using a USAT plate (Freeze-Thaw), and exposure to UV radiation, and prolonged period in an oven with forced air circulation. Chemical analysis using infrared spectroscopy was employed as a tool to better understand the changes in functional groups of the asphalt binder CAP 50/70 and aging effects that can be correlated with rheological performance. Rheological analysis identified a trend of increased stiffness with the incorporation of nanoparticles, as reflected in the parameters of dynamic shear modulus (|G*|) and non-recoverable compliance (Jnr), indicating improved resistance to material deformability at a temperature of 64°C. Results suggest that higher percentages than 5% of cellulose nanoparticles should be used to achieve satisfactory outcomes. The aging procedures demonstrated significant changes in the rheological characteristics of the material. In all cases, fatigue behavior evaluated by Linear Amplitude Sweep (LAS) testing indicated that the incorporation of CNFs does not reduce fatigue resistance despite the increased stiffness. Surface modifications were performed on the nanoparticles to enhance the interaction between CNFs and the asphalt binder, incorporating previously evaluated mass ratios of 2 and 5% and further increasing the incorporation levels to 7 and 10%. However, the obtained results did not indicate significant changes in the rheological outcomes due to the modification itself, but rather due to the high incorporation levels.