Stiffening Effect of Fillers Based on Rheology and Micromechanics Models

Abstract

The aggregate in an asphalt mixture is coated with mastic consisting of bitumen (dilute phase) and filler (particulates phase). The interaction of bitumen and filler and packing of filler plays an important role in the properties of mastics. The micromechanics models from composite rheology can be used to predict the stiffening effect of a suspension. In this research, the stiffening effect of fillers was investigated based on the rheology of mastic. The frequency sweep tests in a dynamic shear rheometer at different temperatures were performed within a linear viscoelastic range to construct the master curves. The volume fractions were expressed as compositional volumes of filler in mastic. The particle shape and surface texture are determined through microscopy. We used six micromechanics-based models to predict the stiffening potential of fillers in mastics. The models include Maron–Pierce, Lewis Nielsen, Mooney, Krieger–Dougherty, Chong, Robinson, and Hashin Models. The results show that the same volume content of filler has a different effective volume. The fillers increase the stiffening effect of the composite, especially at high temperatures. The behaviour of fillers with similar effective volume and packing is identical. The filler type affects the stiffening of mastics. Micromechanics modelling results show that most models show an accurate stiffening effect at lower concentrations with the exception of the Chong Model. The Maron–Pierce Model under-estimates the stiffening potential for granite mastic at higher concentrations beyond the 30% filler content fraction. The value of maximum packing fraction (ϕm) and Einstien coefficient (KE) in the Mooney model are significantly different from other models for limestone and granite, respectively. The line of equality graph shows good agreement of measured and predicted stiffness. It is difficult to precisely model the mastic data with any single model due to the presence of complex stiffening effects beyond volume filling.

Recent progress in oil-in-water-in-oil (O/W/O) double emulsions

“…Viscosity is usually determined by rheometers and is directly related to the proportion of dispersed phase and the droplet size distribution of the emulsions (Malkin et al 2004). In Krieger-Dougherty model, the viscosity of a liquid emulsion can be described as a function of the fraction of dispersing phase (Rahim et al 2021). The theory is also suitable for O/W/O double emulsions (Lutz et al 2009).…”

Characterization Techniques Coupled with Mathematical Tools for Deepening Asphaltene Structure

“…When separated, asphaltenes come in the physical form of dark-brown-to-black friable solids, without a definite melting point, which foam, swell, and leave a carbonaceous residue upon heating [2]. The carbonization and degradation tendency as well as the enhancing effect of asphaltenes on rheological properties such as the viscosity of liquid fuels [3][4][5] have a negative impact on fuel processing technology and utilization, reducing the fuel economic value and causing undesirable effects to the industry using them. Their hindrance on the production and processing in the petroleum industry has required focusing fundamental and applicative research on physical and chemical characterization asphaltenes to understand how to separate asphaltenes from the petroleum before the refining processes or to obtain their "upgrading" to a less refractory (lighter) fraction (e.g., via catalytic cracking).…”