Roofing product including roofing-grade asphalt mixture and methods of making the roofing product and the roofing-grade asphalt mixture

A method of forming a roofing product consisting of:

• mixing (i) a bio-asphalt consisting of a bio-source material with:
• (ii) a bitumen source material, (iii) particles, and (iv) an optional additive chemical selected from the group consisting of a process oil, a plasticizer, a polymer modifier, or combination thereof to form a roof-grade asphalt mixture,
• wherein the bio-source material consists of a partially oxidized bio-source material,
• wherein the bitumen source material has a penetration distance of no greater than approximately 14 dmm, wherein the bitumen source material is different from the bio-source material and the bitumen source material consists of petroleum-based asphalt,
• wherein the bio-source material is at least approximately 5 wt % of a total bitumen content;
• and
• applying the roofing-grade asphalt mixture to a base material, wherein the roofing-grade asphalt mixture has a softening point of at least approximately 104° C., a viscosity of at least approximately 3000 centipoise at a temperature of 177° C., and a penetration distance of not greater than about 30 dmm.