Self-level concrete not stuck

Discussion in 'Other Trades Talk' started by Ad_Stewart, Oct 2, 2019.

  1. Ad_Stewart

    Ad_Stewart New Member

    I suppose this should be under ‘flooring talk’ but there isn’t one so here goes!

    I put an epoxy DPC on top of an old concrete slab in the kitchen where the existing DPC had failed.
    I rolled 2 coats and the 2nd coat was ‘blinded’ with dry sand before it was set.
    This was as per instructions which said it was suitable for screeds if prepared like this.

    I used 6 bags of self level compound for 10 m2 in the recommended mix and this brought the concrete floor up to the level of the floorboards in the dining room in a single layer (I’d estimate 3-4mm since it flowed itself with minimal trowelling in the edges/corners).

    No problems for 10 days but today there are hairline cracks everywhere and when tapped it sounds like it has not adhered in some (not all) patches.

    options:

    1) leave it and put laminate and underlay as planned

    2) chisel it all up and glue 4mm ply onto the epoxy layer (likely not to give me such an even join between floorboards and slab)

    3) Any other ideas?


    My new kitchen is supposed to be getting fitted in 6 days so I need a solution over the weekend!
    [​IMG][​IMG][​IMG][​IMG]
     

    Attached Files:

    Last edited: Oct 2, 2019
  2. DIYDave.

    DIYDave. Screwfix Select

    I’ve only got 30 seconds but unfortunately, after the liquid DPM, a coat of SBR should have been painted/rolled over the DPM

    This would have aided the bond between DPM and self leveller, without the added sand

    What brand SL did you use and too late now unfortunately but check with their tech department

    If it’s cracked now and sounding hollow, seems a bad move to proceed with finished floor as gonna come back and bite you I fear

    Sorry but situation don’t sound good

    Others will add, I’ve gotta fly
     
  3. KIAB

    KIAB Super Member

    I would have used a acyrlic primer or SBR slurry on dpc blinded before using leveling compound,stops cracking from drying too quickly either from room heat or dpc, sucking out moisture.
     
  4. DIYDave.

    DIYDave. Screwfix Select

    The blinding of sand has stopped the SL from adhering to the sub floor

    Same as you dust your worktop with flour before rolling out pastry ...... stops it sticking (good in this case)

    Where did you get ‘instructions’ from ?

    Now really gotta dash !
     
  5. Ad_Stewart

    Ad_Stewart New Member

    Argh. I’ve got SBR. I didn’t use it as the epoxy was dust free and thought SBR was just to seal dust! There was no loose sand when I poured.

    Epoxy was from Permagard. From the instructions:
    “If you wish to lay tiles or adhere any further coatings including self leveling compounds on top of this coating we advise that you blind the final coat of Epoxy DPM with fine quartz aggregate 30 minutes after laying the coat to provide a key for the tile adhesive or grout to bond to.”

    Self level was mapei from screwfix:
    https://www.screwfix.com/p/mapei-ultimate-leveller-1210-self-levelling-floor-compound-20kg/4377v

    If I hacked it up and re-poured the concrete could I be sure it wouldn’t happen again or is ply a better option?
     
  6. KIAB

    KIAB Super Member


    You can add clean sharp sand to many liquid dpm's like synthaprufe,etc for blinding.
     
    Astramax likes this.
  7. Ad_Stewart

    Ad_Stewart New Member

    I used a very fine paving sand which I actually dried in the oven to make it scatter evenly! The quartz aggregate was too pricey from Permagard.
     
  8. DIYDave.

    DIYDave. Screwfix Select


    Yes yes I’m diy I know, don’t pretend to know it all but just trying to be helpful and, have levelled a ‘few’ floors (certainly not a world expert on the subject, don’t mind admitting)

    But ........

    When you say ‘add sharp sand to liquid dpm’s’ Do you mean like actually stirring the sand into the dpm before using ?

    Same as you can do with self leveller to help bulk it out, ie add extra sand as sand is cheaper than SL

    But in this case, yes the OP has followed instructions but the sand has been added some time after laying the liquid dpm, as a blinding coat

    Something has stopped the two materials from bonding ?

    Just wondering if the layer of ultra dry sand is acting like the flour on my pastry slab

    Again yes, the OP has followed instructions provided by the liquid dpm supplier - Permagard

    I wonder if you speak to Mapei what would they recommend when pouring their SL over the Permagard

    To late now I realise but need to know best way forward
     
    KIAB likes this.
  9. Ad_Stewart

    Ad_Stewart New Member

    The sand actually sunk into the epoxy (think a sandpaper like finish) but admittedly not uniformly. Some patches were rougher than others.

    likely not enough time to get an answer from mapei for the best option but I’ll try!

    Unless anyone can give me any assurances, I can’t risk the same thing happening again if I just did the same as before with SBR. Might be forced down the 4mm ply option.....
     
  10. KIAB

    KIAB Super Member

    If you used SBR as a slurry,then your leveling compound should have stuck,but I have never used Mapei, usually Setcrete, but some jobs Ardex.
    As to primer, it's normally Setcrete acrylic primer,which can be used on various surfaces,including sound asphalt, well bonded epoxy and polyurethane coatings and minimal existing adhesive residue.

    http://www.setcrete.co.uk/product/acrylic-primer/
     
  11. Ad_Stewart

    Ad_Stewart New Member

    What do you mean by SBR slurry? Is it adding it to the levelling compound when mixing?
     
  12. Astramax

    Astramax Super Member

    Done that many times KIAB without any problems ever.
     
    Ad_Stewart and KIAB like this.
  13. DIYDave.

    DIYDave. Screwfix Select


    SBR Slurry is simply cement powder mixed into neat SBR to give a thick, brushable coating. Exact ratios will be available for brand of SBR, but if your doing this regularly, I would imagine most will just eyeball it

    I realise uv followed instructions from Permagard and it’s not worked - damm annoying and costly

    Call Mapei tech line and discuss with them, they may not wish to give advice when mixing their products with another brand but just mention using their SL over a epoxy dpm, what prep is needed

    Also call Permagard and see what they say - you’ve followed their method to the letter

    Good luck and please report back
     
    Ad_Stewart likes this.
  14. KIAB

    KIAB Super Member

    Don't want it too thick, I usually aim for a not too thin creamy consistency,lay leveling compound when SBR is tacky, if SBR dries then give it another coat.
     
    Ad_Stewart likes this.
  15. DIYDave.

    DIYDave. Screwfix Select

    Let’s consider though the OP has laid an ‘epoxy’ liquid dpm

    Often on here liquid dpm mentioned and the bitumen type frequently discussed. I’ve used Everbuild Black Jack a few times with self leveler over the top, coat of SBR 1-4 with water in-between, been great

    Would be wise for the OP to discuss issues with both Mapei and Permagard

    Permagard instructions do say to blind with ‘quartz granules’ 30 minutes after coating with epoxy

    OP used fine paving sand, I’ve no ideas what the difference is but unfortunately something has gone wrong between the materials
     
    Ad_Stewart and KIAB like this.
  16. Ad_Stewart

    Ad_Stewart New Member

    I’ve reached out to mapei but no reply yet, I also posed as a customer to other epoxy DPM suppliers to see what they would recommend. Weberfloor recommended exactly what I did (but with coarse sand) and with the addition of the primer (which I didn’t do *facepalm*)

    Do I need to buy a specific acrylic primer like KIAB recommended or is 2:1 diluted SBR the same? Is a slurry coat better before the self leveller or 2 coats of primer?
     
  17. Ad_Stewart

    Ad_Stewart New Member

    Turns out BAL SBR isn’t suitable for non-porous surfaces, setcrete looks like the winner and it’s available at Wickes. 61295212-0AD0-4543-8D3A-522A8162A27D.jpeg
     
  18. Ad_Stewart

    Ad_Stewart New Member

    Update:
    At least it lifts easily. It’s clearly not bonded to the epoxy in the slightest.

    I’ve watched a YouTube video where someone rolls ‘Stopgap p131’ straight onto a glossy epoxy finish. Does anyone know whether the setcrete acrylic primer has superseded this? I’ve noticed ‘ball’ products have the same logo as ‘setcrete’ and wonder if they’re the updated range with a new name.

    74110D6E-1C73-4B6E-BDFB-821405B96633.jpeg C3A49D1B-ADDE-4FE0-9733-2BE00EFD677F.jpeg
     
  19. KIAB

    KIAB Super Member

    Setcrete products have been made by F Ball Ltd for years.
     
  20. Ad_Stewart

    Ad_Stewart New Member

    Do you know if the p131 is equivalent to the acrylic primer you recommended? P131 is described as a ‘neoprene primer’



    (voiceover guy is the same!)
     

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