Wire brush the bitumen, clean and prime with SBR.
I would use any s2 type adhesive.
The elastic polymer in it acts as an adhesion enhancer enabling it to stick better to the bitumen.
I'm sure that the other guys here will have different solutions.
Sounds Ok to me. Never used SBR before but just read Perma Gard's spec sheet for it, seems straightforward enough to apply.
Thanks a lot bighen:hurray: