Ranking of EVA Modified Bitumens Based on AASHTO M320 Performance Related Parameters

摘要

The AASHTO M320-10 bitumen specifications, and the measurements upon which they are based, are designed to provide performance-related properties that can be related in a rational manner to pavement performance. Some reports suggest that the AASHTO M320 specifications are well-suited for dealing with unmodified bitumens. However, a number of studies question the validity of the AASHTO M320 specifications for modified systems. This paper investigates the use and suitability of AASHTO M320 bitumen parameters for ranking of plastomeric polymer modified bitumens. Two methods were used for the ranking of a series of ethylene vinyl acetate (EVA) polymer modified bitumens (PMBs) in terms of the three main distress modes associated with flexible pavements of low temperature cracking, permanent deformation (rutting), and fatigue damage. AASHTO M320 bitumen parameters, practical mechanical asphalt mixture properties were used for ranking of EVA PMBs then the rankings were compared. Results show that AASHTO M320 bitumen parameters are valid for EVA PMBs only at low polymer contents. It is an important conclusion because the high cost of polymers makes the commercial use of modified bitumens only attractive for road construction if the amount of polymer is relatively small.