They must have a nest. Here's a link that tells you how to get rid of them:
Powdered boric acid.
find their home too.
Find the nest and apply ortho liquid insect control on a wind free day. It smells, so take precautions. Repeat application may be needed, but the product is effective.
Look for any evidence of sand, which attracts ants. You can try applying soapy water with lemon oil to these spots.
Note that vinegar can damage concrete products, used over time.