take a picture of it once its been cleaned and post it here.
If you have a black car I would HIGHLY recommend getting an electric orbital polisher. Lowes sells the Porter Cable orbital polisher for under $130.
a two step swirl remover liquid paste like Poorboys SSR or Menzerma Intensive Polish will make your paint look brand new, even in the direct sunlight.
If the scratch didn't penetrate through the clear coat and damage the base layer you should be able to fix this with the polisher. If the cement did damage the base layer then you've got to have it repainted. Matching faded black paint can be a real pain in the arse, proceed with caution.
this guy has a useful site for maintaining his black car
www.paintcare-n-detailing.com