Avaliação reológica de ligantes asfálticos modificados com nanopartículas de dióxido de titânio.

Abstract

Researches have been carried out on improving the performance of asphalt binders so they can be durable, present less permanent deformation and longer fatigue life. For this, asphalt binder modification techniques have been used, e.g. polymers, fillers, fibers and, more recently, nanomaterials, which have presented technical and economic feasibility. This research aims to study the incorporation of titanium dioxide nanoparticles in the modification of asphalt binders CAP 50/70 and 55/75-E. The nanoparticles were added to the base asphalt binder at concentrations of 3, 4 and 5% of weight, in both pure and surface modified states. Three different agents were used for the surface modification: oleic acid, benzyl alcohol and oleylamine. The research was divided into four stages: the first one consisted in the analysis of the Fourier transform infrared spectroscopy (FTIR) of these binders, in the second one the binders were evaluated by means of physical (penetration and softening point) and rheological [rotational viscosity, performance grade (PG), multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS)] tests, in the third stage the binders were exposed to natural UV radiation and thermal variations during a period of 3 months and analyzed by means of FTIR and rheological tests, and the last stage consisted in the surface modification of the nanoparticles. The results indicated the technical feasibility of the incorporation of TiO2 nanoparticles to the binder CAP 50/70, since it increased fatigue life, resistance to deformations and delayed the aging process. In addition, the surface modification of the nanoparticles with oleylamine improved the interaction of the particles with the binder, contributing to the improvement of the parameters mentioned above. The incorporation of nanoTiO2 to the 55/75-E binder did not provide as significant results as the observed for CAP 50/70, although it presented better results than the base binder. The incorporation of surface modified nanoparticles with oleylamine to the 55/75-E binder provided higher resistance to aging and less susceptibility to permanent deformations and cracks, although less expressive than the verified for CAP 50/70.