Need self-levelling screed?

[Bozza]

7 hours ago, jpadie said:

two days later and the moisture content of the screed is 30%.  fan on all the time.

question is whether i can still prime some patches before laying some more SLC or if it has to be dry.
the primer is mapei primer g - the info says it can be used between levels of SLC but the layer must be "perfectly dry".  does that mean down to 3% RH or just not puddling with water?  seems really odd since the primer needs diluting with water too!

also seems odd that a quick setting SLC poured at 5-9mm is still at 30% RH after two days when it's supposed to be ready for wood flooring after 2 days (which requires 4% moisture or lower).

I think you mentioned in an earlier post about using extra liquid, so if that means you watered down the mixture more than needed that may be why.  Soz if I’ve misunderstood.  

[jpadie]

there's no puddle.  the colour of the screed is patchy though.  the gauge is for wood and relies on probes that will only really measure surface humidity on a solid substrate like concrete.  it's the wrong approach so I'm going to trust the manufacturer and have spread the primer this evening for a pour tomorrow morning.  fingers crossed.  

[saveasteading]

9 minutes ago, jpadie said:

the gauge is for wood

I think the difference is that the gauge measures conductivity. through wet wood is very different to through wet concrete. I'm sure its fine from what you've said and done.

If the repair is still damp you've sealed it so tats good too.

[jpadie]

The new screed is down. I didn't have enough bags sadly (despite buying two more than the calcs said were needed).  Poured slow and left to pool before increasing the pour, stopping three inches before the perimeter of the low spots.  Then feathered the edges with a "flamand".  Not sure what these are in English but they are a type of concrete trowel that's about 2ft long and have a pointed snout for corner and more detailed work.  

I think I'll still be a wee bit off in some areas due to the missing bag.  But probably only a mm which is within measurement tolerance and will be absorbed by the 3mm foam and foil that goes down.  I forgot to leave a gangplank so it's down tools for a few hours before going back to measure the door frame height and decide whether to thin down the door header.  It's in a partition wall so not load bearing.