A mixture made from or containing T1) from 99 wt % to 75 wt % of bitumen, and T2) from 1 wt % to 25 wt % of a polymer composition made from or containing A) 5-35% by weight of a propylene ethylene copolymer; B) 20-50% by weight of an ethylene homopolymer; and C) 30-60% by weight of a terpolymer of ethylene, propylene and 1-butene derived units.