Joints between old and new concrete

Discussion in 'Subfloor Preparation' started by Mwfloor, Aug 9, 2019.

  1. Mwfloor

    Mwfloor Well-Known Member

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    Hi

    What’s everyone’s system for preventing movement between an existing slab of concrete to a new one? [​IMG]

    (See pic)

    The left side of pucture was the original concrete, the right side was an Agilia Screed, which I Grinded down, and left to dry until 75% RH then screeded.

    For future reference is there a jointing compound I can use to minimise movement like this? F77 with sand etc, or mesh. Any advice would be appreciated as I’m always looking to learn and improve.

    Also in terms of making this good how long should I leave it before I attempt to fix it. As I don’t want a repeat


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  2. tarkett85

    tarkett85 Well-Known Member

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    The concrete needed an expansion joint between the old and new.


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  3. merit

    merit Well-Known Member

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    Uzin and shonox do a mesh system. I’ve also seen a system with metal pins chased into the concrete and filled with epoxy. Or you could use a decoupling matt. Most these systems are for cracks and not 2 separate slabs that can move differently. You probably won’t get a manufacturer guarantee any of it. They will advise you put a movement joint where the crack is on the floor. No customer will accept that unless it’s a retail or commercial building. I always try to use a floated system over separate slabs like jumpax


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  4. Spacey

    Spacey Super Moderator Staff Member

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    Needs metal stitches and resin then uzin RR203 laid over embedded in 888s Then another coat to smooth then refit planks
     
  5. Mwfloor

    Mwfloor Well-Known Member

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    Thanks for the feedback, can you advise what metal stitches and who makes them? I mainly use balls products so will f77 suffice as a resin with on its own without sand?


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  6. Mwfloor

    Mwfloor Well-Known Member

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    Thanks for the info, real bitch this has moved like it has I blame the extreme weather we are having. Do you always use jumpax with a joint between old and new slabs then? I’m doing them all the time so need to implement options, what jumpax would you use usually..


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  7. Spacey

    Spacey Super Moderator Staff Member

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  8. Spacey

    Spacey Super Moderator Staff Member

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    That would have happened no matter what the weathers doing You can't screed over cracks and joints with out using some kind of crack repair or crack bridge or expansion joint
     
  9. merit

    merit Well-Known Member

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    Yeah try to always float over separate slabs. Jumpax original. It’s a bit more time consuming to install but the finish is perfect and no feathering.


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  10. Rugmunching

    Rugmunching Well-Known Member

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    Ardex rep gave me some of their stitch system to try out, used one before but cant remember who's it was
     
  11. Distinctive Adam

    Distinctive Adam Well-Known Member

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    Floorfixx or a resin crack repair, Uzin, Murexin, schonox, Ardex
     
  12. dazlight

    dazlight Super Moderator

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    Where was this job mate? Just speaking to a lad on holiday who was telling me happened to his. Said it’s been sorted out now.
     

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