Even a small spill of kerosene on concrete can leave a lasting impression. Concrete is so porous that contact with a strong-smelling liquid like kerosene can leave an odor that clings for weeks -- an odor that washing alone may not eliminate. It's not that it's difficult to remove the kerosene smell. You just need to use the right products.
Sprinkle the area with baking soda to deodorize the concrete surface. Allow the powder to sit for a couple of hours or overnight.
Scrub the baking soda on the concrete with a nylon-bristled scrub brush. Rinse the concrete well. Allow the concrete to air dry, or, if it's indoors, dry it with an old towel.
Place 2 pounds of volcanic ash minerals in a mesh bag; you may purchase the minerals already packaged in a breathable bag, in which case you should use it as-is. Place the bag on the concrete and leave it overnight to remove any remaining kerosene odor.