409 is an excellent degreaser... The US Navy uses it to clean their jet engine parts. Saved millions of dollars compared to the commercial degreasers. And Purple Degreaser By Gunk is also a good product that you can use on concrete and asphalt. Also, if you are pressure washing, you need to get a concrete scrubber. Basically its a brush/jet contraption that you can attach to your power washer. They run around $150 at the pressure washing equipment co's. BUT they are well worth your money when it cuts your time doing driveways and sidewalks by half (or more). When I owed my parking lot sweeping business we did a lot of asphalt/concrete repair and cleaning. If you have any specific questions just shoot me a pm.

later.
Pappy