International Journal of Pavement Engineering · 2014 · 42 citations · 25 references
EngineeringMaterials EngineeringMaterials ScienceMechanical Behavior Of MaterialsPolymer EngineeringRheologyAsphalt MaterialsBituminous MaterialsCreep BehaviorPolymer RheologyViscoelastic BehaviorViscoelastic PropertiesAsphalt RheologyBitumenBitumen ModificationDeformationPolymer-modified BitumenRheological MeasurementsRheology Of Bituminous MaterialsViscoelastic Effects
The main objective of the present study was to determine the effects of longer loading–unloading times on the per cent recoveries (R) and the non-recoverable compliances (Jnr) of bitumens modified with polyethylene (PE), polyphosphoric acid (PPA) and both additives (PE+PPA). These effects were quantified by means of ratios of R values and Jnr values at one test condition to another test condition, and the best formulations were reported. The base bitumen is graded as PG 64-xx and the modified bitumens have the same high PG grade (PG 76-xx). All the materials showed lower R values and higher Jnr values with increasing creep and recovery times from 1/9 s to 2/18 s, which indicates that they are more susceptible to permanent deformation when both times are longer. These higher Jnr values at 2/18 s and the high PG grade can be mainly attributed to the increase in the viscous portion of the viscoelastic response of the bitumen.
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