Patio slabs discolouring

Discussion in 'Builders' Talk' started by Tracie G, May 28, 2010.

  1. Tracie G

    Tracie G New Member

    I laid a patio with yellow riven comcrete slabs 12 months ago, the slabs have gone decidely grey and patchy and I think it is the salts leacing out of the concrete. Anyone got any ideas for cleaning this off, the only thing I could think of was brick acid but concerned this will disolve or bleach the slabs!!! I do have a karcher bur again concerned it will either just give them a good wash or drill interesting patterns in the slab surface. The only cleaners I have found seem to concentrate on algae or oil. It is quite a big patio so any advice that avoids spending the next 6 months on my kneees with a stiff brush welcomed.
     
  2. ecm²

    ecm² New Member

    Don't use brick acid it's too harsh and don't use a pressure washer you will wash the joints out over time. The best way is mild detergent (baby shampoo is ideal) and a stiff scrubbing brush - I know you said you wanted to avoid this but it is the best way. If you get on your hands and knees you can target the slabs and avoid the softer mortar pointing.

    I've just done mine after 3 years after laying them (natural sandstone) and they have come up lovely.
     
  3. Mr GrimNasty

    Mr GrimNasty Active Member

    With some of these coloured slabs, made with cheap dye, it's just as likely they are fading/changing colour.

    You could just let them weather down naturally.

    Or if you can clean it off, or they look better wet, you could apply a sealer which might help preserve a newer look.
     
  4. cwb

    cwb New Member

    hi, if your getting a salt like mineral coming from your flags, dab the affected area with a damp cloth and neat household beach, regarding the colour, direct sunlight will be bleaching the colourdye out of them. you could try painting them with masonary paint.
     
  5. ecm²

    ecm² New Member

    With some of these coloured slabs, made with cheap dye, it's just as likely they are fading/changing colour.

    Yes you're quite right Mr Grim - that's probably what's happened. For some reason I thought the OP said they were sandstone, but as you point out they are concrete. The cheaper dyed concrete flags (red and buff in particular) fade very quickly and look naff after a couple of summers.
     
  6. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    If the fading disappears when they are just made wet, then most probably a sealer will have the same effect, but won't dry back to fade. Thompsons Patio Sealer gives a buff looking slab a slghtly wet look(eg from matt to say satin effect). More coats, more shiny(and darker).


    Mr. HandyAndy - Really
     

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