Alternative interpretation of the adequate traffic levels of modified bitumens on Superpave (R): a case study with crumb rubber and polyphosphoric acid (PPA)

Author(s)

Inocente Domingos, Matheus David ; Faxina, Adalberto Leandro

• Document type: Journal article
• Source: Road Materials and Pavement Design; v. 20, p. 15-pg., 2019-06-20.

Abstract

This study proposes an alternative interpretation for the choice of modified bitumens on Superpave (R), according to which heavier traffic levels described in the standardised bitumen classifications must comply with one additional requirement for the material to be graded as H, V or E. In order to show the application of this proposed interpretation, modified bitumens were subjected to MSCR tests at five temperatures (52 degrees C, 58 degrees C, 64 degrees C, 70 degrees C and 76 degrees C) and four creep-recovery times (1/9, 2/9, 4/9 and 8/9 s). Crumb rubber and polyphosphoric acid (PPA) were used as modifiers to prepare three formulations: bitumen + PPA, bitumen + rubber and bitumen + rubber + PPA. The proposed criterion identified decreases in the traffic levels from E to V for the bitumen + rubber + PPA at 58 degrees C and the bitumen + PPA at 64 degrees C. This suggests that such bitumens may not be appropriate for heavier traffic levels, and a deeper investigation of their permanent deformation performance at the asphalt scale should be carried out. (AU)

• FAPESP's process: 13/20483-6 - Effects of Different Creep and Recovery Times on the Rheological Properties of Modified Asphalt Binders
• Grantee: Matheus David Inocente Domingos
• Support Opportunities: Scholarships in Brazil - Doctorate