During the masonry work , lots of things like this got spoiled due to careless workmanship.

How should I remove the concrete without really damaging the steel behind it ?

I tried scratching it with water , it didn't help.

If I use metal scrubber , I'm afraid the nice coating behind the roof sheet will be gone.

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  • 1
    If the careless workmanship was done by hired contractors, talk to the company about cleaning up their mess.
    – FreeMan
    Oct 3, 2023 at 16:39
  • @FreeMan - It's hard to get them to clear their mess. It'd save lots of time , if I do this by myself.
    – Amogam
    Oct 3, 2023 at 16:45
  • They leave the mess behind because nobody holds them accountable for their careless work...
    – FreeMan
    Oct 3, 2023 at 16:46
  • I understand , I will try to get in touch with them and see what happens
    – Amogam
    Oct 3, 2023 at 16:51

1 Answer 1


An acid will attack Portland cement. CLR cleaner for bathroom mineral deposits is acidic (pH of around 2.5), where the stuff has a thickening agent that will help it stick to the underside of a surface like that. Find an inconspicuous spot on the same painted surface to verify that the CLR doesn't damage your paint. If the test is successful, then apply it to the concrete stain.

  • Great,Thanks for pointing out CLR(Calcium Lime Rust) Cleraner. I will try this and see how it works.
    – Amogam
    Oct 3, 2023 at 0:13

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