Asphalt binder with a polymer, most often styrene-butadiene-styrene (SBS) at roughly 2 to 5 percent, dispersed or crosslinked into it. The polymer forms a rubbery network that gives the binder elastic recovery, so it springs back under heavy wheel loads instead of flowing, and it widens the temperature range the binder can serve. It is the usual route to high grades like PG 76-22 and needs hotter mixing and compaction temperatures than neat, unmodified binder.
It's PMA, so keep the breakdown roller right on the screed, this stuff stiffens up fast once it drops under 270.
Modified binder grabs everything it touches, so rakers keep lutes wet with release agent and roller operators keep tires hot.
Also heard as
- PMA
- modified binder
- SBS-modified asphalt
- modified
Related terms
Asphalt binder
The black, sticky petroleum cement that glues the aggregate together in an asphalt mix.
PG
Performance Grade: the binder rating that names the hottest and coldest pavement temperatures a binder can handle.
MSCR
Multiple stress creep recovery: a high-temperature binder test measuring how much of a deformation the binder recovers.
SMA
Stone matrix asphalt: a gap-graded, binder-rich surface mix built on a stone-on-stone skeleton.