Estudo entre escalas de ligantes e misturas: investigação do comportamento viscoelástico linear e parâmetros de dano dos materiais asfálticos

Abstract

The most common distress in the asphalt coating layer of the country's highways are permanent deformation in the wheel tracks and fatigue cracking. The phenomena of cracking and permanent deformation that occur at the sidewalk scale are closely related to phenomena inherent to the smaller scales. Much has been discussed about the importance of performing both rheological and damage tests to obtain definitions of the behavior of asphalt mixtures from the binders. For when it comes to the repetition of the flows of loads and deformations in the field, in the laboratory this action is limited to the state in which the sidewalks are. Furthermore, the elasticity and viscosity principle on which the modeling is based is limited to field situations and does not take into account factors such as temperature, load variation, and strain recovery in the asphalt mixture. Thus, it becomes necessary to use mathematical models that resemble reality conditions Based on this context, this study investigates the linear viscoelastic behavior and damage parameters of asphalt binders extracted and recovered from the 20 dense asphalt mixtures applied in both restoration and highway implementation works in the state of Rio Grande do Sul between March 2016 and August 2017. This research is based on the data obtained from the viscoelastic properties and the Flow Number parameter presented by Faccin et al., (2021), in addition to the uniaxial cyclic tensile-compression fatigue test with application of the simplified continuous damage viscoelastic model (S-VECD), produced by Schuster et al., (2021), for the same mixtures, which served as a basis for the correlations between binder scales and asphalt mixtures. Based on this information, it was concluded that the samples used in the State of Rio Grande do Sul indicate varied rheological behavior in the linear viscoelasticity domain. This occurs due to the design of asphalt mixtures that have great influence on the stiffness (binder content, type of granular NMAS, presence or absence of active filler, fines content, particle size distribution and angularity of aggregates), i.e., all these factors influence and may be greater than simply the stiffness of the binder. From this were, both PGH and |G*| 65°C 1Hz and |G*|/sinφ 65°C 1Hz are good indicators, especially when checking field data. Furthermore, in terms of permanent deformation, although the FN parameter does not result in a satisfactory indicator between the scales of binders and mixtures, it is found that perhaps the problem is not the binder and, rather, the FN. For when stiffness is analyzed in PGH and when field relations are inserted, it is noted that they are better indicators than FN, thus realizing that perhaps FN is not a test with a level of perfection imposed in this research. Finally, the parameters of Jnr3.2, |G*| 65°C 1Hz and |G*|/sinφ 65°C 1Hz appear to be good indicators/markers for the field, since when the indicators of both Jnr3.2 and stiffness and field are analyzed, the correlations between the scales are satisfactory, so perhaps FN is the problem for this particular case. It should be pointed out that regardless of the failure criterion, in general it is observed that the samples with polymer addition when correlated are higher on the scales and to the right indicating mixtures with better qualities provided they are dosed properly, in other words, the mixtures with the polymermodified binder will perform better and apparently all the slopes are favorable, fitting the premise that the higher the FFL, the higher the FFM. And while no criterion is excellent, Max PSEs is the best criterion for some cases and others are not, as indicated in this research. Therefore, it is concluded that the growth rate that the higher the FFL, the better the FFM for comparing two materials/products works adequately and that the blends produced with the polymeric materials provided they are well metered, overall, produce blends with higher FFM.