A method of forming an asphalt mixture can include mixing a bio-source material and a bitumen source to form a bitumen mixture. The bitumen mixture can be mixed with a catalyst to form the asphalt mixture. Particles can be added to the asphalt mixture to form a roofing-grade asphalt mixture. In an embodiment, the bitumen source material can have a softening point of at least approximately 93° C. and a penetration distance no greater than approximately 25 dmm. In another embodiment, the roofing-grade asphalt mixture can have a softening point of at least approximately 104° C., a penetration distance no greater than approximately 12 dmm, a viscosity of at least approximately 3000 cps at a temperature of 204° C., or any combination thereof. The asphalt mixture can be applied to a base material to form a roofing product. The asphalt mixture can be applied as a pavement product.