How do you tell which type of new slab is down?

Discussion in 'Subfloor Preparation' started by Jason Sheehan, Apr 12, 2021.

  1. Jason Sheehan

    Jason Sheehan Well-Known Member

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    Just curious how you lot ascertain which type of slab is down ie gypsum or cement based slab? I'm going on the basis you cannot get a datasheet. For example I hear some use a pint of full fat milk poured on top helps but in end whichever the slab isn't the slab preparation the same bar possible dpm? Again very curious the extent folk here goto on prep and why.
     
  2. Neilydun

    Neilydun Well-Known Member

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    For the most part I can tell by looking. If there is any doubt, then if its new build, you should be able to ask the MC what exactly has been laid.
    Often ifs its new build, they may still be pouring on site.
    The top of gypsum is often powdery and can be scraped/ground off.
    Its important its identified, so it can be treated correctly.
    Never used milk...
     
  3. dazlight

    dazlight Super Moderator

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    The milk thing was a wind up I did. :D
     
  4. Neilydun

    Neilydun Well-Known Member

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    U gotta lota bottle Daz
     
  5. Jason Sheehan

    Jason Sheehan Well-Known Member

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    Haha I was like.. really? Thankfully I never tried but still :D
     
  6. merit

    merit Well-Known Member

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    Not many builders can get a dry mix screed flat so if it’s flat it’s probably a liquid. Also you can tell round the edges of a screed if it’s been poured or troweled. Gypsum is mostly light and soft.


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  7. Neilydun

    Neilydun Well-Known Member

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    And if you tap it in the corner, the corner breaks off ;)
     
  8. dazlight

    dazlight Super Moderator

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    If you get a tea bag and :D
     
  9. merit

    merit Well-Known Member

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    If you lick it it’s salty


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  10. Neilydun

    Neilydun Well-Known Member

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    I thought this was a flooring forum
     
  11. merit

    merit Well-Known Member

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    Oops


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