Aplicação de nanopartículas bimetálicas de zinco prata (ZnAg) como modificador de propriedades de ligantes asfálticos.

Abstract

The use of high-performance asphalt binders can be used to minimize premature degradation of asphalt coatings. These binders are obtained by incorporating an additive agent into the virgin binder. Nanomaterials stand out for providing binders with adequate resistance to high traffic loads under adverse external conditions. Bimetallic nanoparticles (BNPs) have emerged as an alternative to metallic nanoparticles (NPs) since they present increased electronic interaction between the individual metals. The properties provided by silver related to those of another material, such as zinc oxide, make it possible to obtain a more efficient nanocomposite for certain applications. Therefore, this research evaluated the interaction of the modification of the asphalt binder CAP 50/70 with contents of 3, 5 and 7% by mass of unmodified ZnAg bimetallic nanoparticles and surface-modified by oleylamine. These binders were evaluated through empirical, chemical and rheological tests. The chemical results demonstrated that the modification of asphalt binders by nanoparticles leads to only physical associations, not promoting chemical changes in the asphalt matrices. The use of bimetallic zinc-silver nanoparticles provided better performance of the curing index to the asphalt binders, which went from 5.66% of the reference binder to 7.74%, 10.87% and 16.07% for the non-surface modified binders with 3, 5 and 7% respectively and 7.60%, 9.43% and 9.60% for the surface modified nanoparticles with 3, 5 and 7% respectively. Therefore, an indication of better fatigue performance of these binders, that is, a probable longer service life of the pavements. The results presented by the master curves allowed us to confirm that the addition of surface-unmodified ZnAg BNPs made the asphalt binder more rigid by approximately 40% at high temperatures, making the binder more resistant to permanent deformations at these temperatures, and approximately 24% less rigid for the binder with 7% at low temperatures, which can provide greater elasticity to the mixture, making the binder more resistant to fatigue cracking. In general, the results indicated that the addition of ZnAg BNPs promoted benefits to the asphalt binder in terms of increasing consistency, yield strength, permanent deformation and resistance to fatigue cracking, with better results presented at the 7% ZnAg BNPs content. The addition of modified ZnAg BNPs caused subtle changes in the properties of the binders.