Influence of Mineral Fillers and Their Fractional Voids on Mastic Rheological and Mechanical Properties

Abstract

Mineral fillers are added into asphalt mixtures to stiffen asphalt binder and improve mixture density and strength. The stiffness of the mastic affects the ability of the mixture to resist permanent deformation at higher temperatures, influences stress development and fatigue resistance at intermediate temperatures, and influences stress development and fracture resistance at low temperatures. In this study, the effect of mineral fillers and their fractional voids on mastic rheological and mechanical properties is evaluated. Four types of filler with different physical properties were investigated. The fillers were associated to four asphalt binders, including unmodified and polymer modified binders, to obtain 16 asphalt mastics. The rheological properties of the mastics were evaluated conducting Superpave testing procedures, including the dynamic shear rheometer (DSR) and the bending beam rheometer (BBR). Their mechanical response was investigated using a Modified Direct Tension Test (MDTT), also employing a completely redesigned in-house developed Digital Image Correlation System (DIC) capable of accurately capturing localized or non-uniform stress distributions. The results showed that the Rigden fractional void is an effective indicator of filler stiffening effect, but it cannot be employed to evaluate the interaction between asphalt binder and filler. The effect of filler volume fraction on mastic performance depends on the binder employed.

Laboratory Evaluation of the Relationship of Asphalt Binder and Asphalt Mastic via a Modified MSCR Test

“…For the modified asphalt mastic, viscosity significantly increases with increasing filler content, but the increase is not significant for neat asphalt mastic [19]. The filler volume fraction is also determined for the mastic depending on the asphalt binder used [20]. In addition, the mastic exhibits both linear and nonlinear viscoelastic behavior like that of the asphalt binder.…”

Investigating the Influence of Rigden Void of Fillers on the Moisture Damage of Asphalt Mixtures

“…Notably, this approach emerged as the sole independent parameter capable of effectively distinguishing suitable fillers from unsuitable ones. Furthermore, Romeo et al (2016) validated the utility of Rigden Void as an indicator of asphalt hardening filler [4]. Their study highlighted those fillers with larger Rigden Void values exhibited an enhanced capacity for absorbing and dispersing independent asphalt, consequently improving the frictional characteristics of the filler particles, as documented by Zhang et al (2019) [5].…”

“…Contemporary asphalt research increasingly incorporates waste natural materials, such as coconut peat and bagasse. Notably, some researchers have found that substituting asphalt with bagasse ash can enhance the stability of Hot Mix Asphalt (HMA) in Marshall specimens [4,5,42]. Recently, bagasse and coconut peat fillers were employed to assess workability and measure pull-off tensile strength [43].…”