Evaluation of binder recovery methods and the influence on the properties of polymer modified bitumen

In hot mix asphalt, binder extraction in combination with a recovery method is commonly used to evaluate the properties of a binder embedded in an existing pavement structure. In some countries, like Germany, specifications on the softening point and elastic recovery are legally required on polymer modified binders (PmBs), after recovery from a pavement.

In hot mix asphalt, binder extraction in combination with a recovery method is commonly used to evaluate the properties of a binder embedded in an existing pavement structure. In some countries, like Germany, specifications on the softening point and elastic recovery are legally required on polymer modified binders (PmBs), after recovery from a pavement.

In hot mix asphalt, binder extraction in combination with a recovery method is commonly used to evaluate the properties of a binder embedded in an existing pavement structure. In some countries, like Germany, specifications on the softening point and elastic recovery are legally required on polymer modified binders (PmBs), after recovery from a pavement. But there are legitimate doubts whether PmBs can be completely recovered.

Especially, for highly modified binders (PmB-Hs) there are more and more indications that part of the polymer fraction is lost in the recovery procedure. As expected this can lead to legal problems when specifications are required on the recovered binders. The purpose of this paper is to evaluate the effect of the recovery method on the properties of PmB-Hs. Three different highly modified binders, prepared with linear and radial SBS polymers, are recovered using three different solvents. Two extraction methods are used: centrifuge and soxhlet extraction.

In addition to a recovery from hot mix asphalt, the PmB-H binder as such, and the non-modified base binder were submitted to the same extraction / recovery process. Several tests including penetration, softening point, elastic recovery, force ductility, gel permeation chromatography and fluorescence microscopy were performed on the fresh, short term aged and recovered binders. The overall purpose of the paper is to determine if, why and to what extend, the properties of highly polymer modified bitumen change in the recovery process.

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Authors

I. Nösler, T. Tanghe, H. Soenen

E&E conference May 2008, Copenhagen