Contribuições ao estudo das propriedades de misturas asfálticas produzidas com ligante modificado por adição de lignina.

Abstract

The use of modifiers in asphaltic binders and, consequently, in asphaltic mixtures, has considerably increased aiming at the improvement of the mechanical behavior and functional performance of pavements, increasing the resistance to permanent deformations and to cracks by fatigue and thermal contraction, and also retarding premature aging. Due to the antioxidant properties, the lignin has been used as a modifier to the asphaltic binder, providing promising results regarding the improvement of resistance to plastic deformations of asphaltic mixtures. Thus, this study aimed at evaluating the performance of asphaltic mixtures produced with binder modified with lignin from the sawdust of pine and eucalyptus in the contents of 3% ,6%, and 9%. Physical (penetration, softening point, and thermal susceptibility) and rheological characterization tests (rotational viscosity, performance grade – PG, fluency and multiple stress creep recovery – MSCR, linear amplitude sweep – LAS) were performed on the pure binder, polymer modified asphalt (PMA) 55/75-E, and binder modified by lignin from pine and eucalyptus; mechanical characterization of the mixtures produced with the modified binder (tensile strength – TS, resilient modulus – RM, moisture-induced damage – Lottman, and dynamic modulus – DM) was also performed. The results indicated that the modified binder provided improvements to physical and chemical properties, increase in the fatigue life and resistance to permanent deformation, and delayed aging process. Regarding the properties of asphalt mixtures, the binder modification positively affected the mechanical properties, contributing to higher resistance to permanent deformation under high temperatures, high abrasion resistance, and lower susceptibility to humidity; the 3% content of pine lignin provided promising results regarding the properties of the binder and asphaltic mixtures analyzed. Therefore, the use of lignin is technically viable, environmentally friendly, as it enables reduction of the inappropriate discharge of material in the environment, and economically viable, as it adds commercial value to an industrial residue. Thus, the mixtures produced with natural polymer can be an alternative to conventional asphaltic mixtures, mainly in regions of tropical climate.