best way to clean an old concrete slab patio?

My patio is about twenty years old and is looking really dirty
i have used a pressure washer on it several times and it cleans it slightly but the black stains are still is made from 2ftx2ft slabs there anything i can try to clean it? or can it be painted ?

6 Comments on “best way to clean an old concrete slab patio?

  1. get a bigger power washer and a wire brush to scrub the concrete

  2. Try a bio soap powder, then an algae remover; don’t paint over dirt, it will prevail.

  3. I use an attachment which Karcher call a T-racer, like on here:

    It’s a fearsome bit of kit, consisting of a set of water jets which rotate at high speed driven by the pressure alone, and certainly cleans aged and blackened patio slabs. I’d suggest caution with delicate paving, newish concrete or tarmac, it’s that efficient.

  4. Stiff bristle broom, soapy water or a recommended product for the job and plenty of elbow grease !

  5. some of those old slabs just don’t power wash a builder .got a good katcher ..cant get my clean ..and you cant paint them ..grin and bear it

  6. You could try Wicks brick and mortar cleaner five ltr tub 12.99, it’s acid based so brush it on and scrub with stiff broom, then try your jet-wash.