Abstract: A process for preparing compatible, selectively hydrogenated block copolymer-modified bituminous compositions comprising blowing a mixture of the block copolymer and bitumen with an oxidizing gas at temperatures of at least 375° C. for at least 75 minutes. The modifying polymer is a selectively hydrogenated styrenic block copolymer and no blowing catalyst is required. Stable bituminous compositions comprising 6 to 25 parts by weight of block copolymer per 100 parts of asphalt are also provided as well as their application as roofing shingles.

Abstract: Bituminous compositions are provided comprising a mixture of linear or radial block copolymers and diblock copolymers. The mass ratio of linear or radial block copolymer to diblock copolymer is in the range of about 5/1 to about 1/5 such that the resulting thermoplastic block copolymer composition mixes readily with bitumen but does not block before mixing. The non-blocking block copolymer composition has a bulk density in the range from about 20 lb/ft3 to about 30 lb/ft3 and includes from about 0.25% to about 10% by weight of a dusting agent. A process for producing the bituminous composition comprising high temperature, low shear mixing is also provided. The bituminous compositions herein provided are useful as road paving and asphaltic adhesive materials.