How long does friction burns to the knee take to heal ? also they did bleed. and i'm using savalon healing gel

Depends: If the wound base is pink and reddish, then probably 1-2 weeks. If the wound base is white, then the abrasion might be deeper, 2-3 weeks. You can wash the area with soap and water and apply an antibiotic ointment to the area, and cover with a dressing. It'll heal faster. If it doesn't heal after 2 weeks, you should go see your doctor.