Establishing Correlations Between Force Ductility and DSR Parameters of Asphalt Emulsion Residues

Abstract

DSR based rheological tests of 5 non-polymer modified and 5 polymer modified asphalt emulsion residues were performed and its relationships with force ductility parameters (AASHTO T300) were investigated. Some results are presented in this paper. One of the observations from temperature sweep test is that as temperature increases, phase angle of an emulsion residue increases, reaches a maximum and then decreases. Polymer modified asphalt emulsions have comparatively lower phase angle than non-polymer modified asphalt emulsions and the maximum phase angle of all the polymer modified asphalt emulsion residues falls below 81° whereas the maximum phase angle of all the non-polymer modified emulsion falls above 87°. MSCR at 58 °C, 70 °C and equal stiffness (2.2 kPa) temperature clearly demonstrates that percent recovery of polymer modified residues are significantly higher than non-polymer modified emulsion residues. In case of 58 °C and 0.1 kPa creep stress, maximum average percent recovery is 7.7 for non-polymer modified asphalt emulsions while the minimum average percent recovery is 29.7 for polymer modified emulsions. Three force ductility parameters namely, f₂ (force at 30 cm), f₂/f₁ and force at 35 cm were correlated with two DSR-based parameters, phase angle and percent recovery at different temperatures. Based on the analyses of linear coefficient of determination values, it is recommended that phase angle and percent recovery of MSCR be used for polymer identification and to replace force ductility requirements (AASHTO T300) for asphalt emulsions. At 58°C, a maximum phase angle of 81° and a minimum MSCR percent recovery of 30 (at 0.1 kPa creep stress) are recommended.