Firstly thanks to Mike Taylor for the suggestion of slate across the
cavity,and thanks to Michael Mcneil for replying to my question about
making a dry mix for screeding.

Yesterday, we made the mix, placed it, but I am now wondering if we
made it too dry!
It compacted in the hand when squeezed, but absolutely no excees
moisture was present.

I wet the slab four times during the day before laying, and PVA'd 5:1
as we screeded.

Even after covering the screed with polythene, the top surface just
became dust, so today I went over the screed with a mist sprayer and
trowelled the surface.
However, it is still suspiciously loose on top.

Should the mix have been wetter, or is it normal for the top to become
a bit loose as it cures?

Is it irredeemable? - am I going to end up needing to seal it or put a
self leveler on to hold it together. Or dig the whole lot out :-(

Thanks in advance

Bill M

It shouldnt be dry and dusty/friarable on the surface. When you laid it
"reasonably"dry did the normal way is to level it of to guides by whatever
method you like, compressing it at the same time, rub it up with a wooden
float then go over the surface with a steel trowel. Yes keeping it moist
should help, my screeder frequently asks me to spray it with a fine mist
spary for 2 -3 days after it has been laid in very hot/dry weather
The mix should be 3-1 washed river sharp sand to cement
Keep it moist/spary with a fine hose spray for a couple of days and see what
happens

(Bill M) wrote in message . com...
Firstly thanks to Mike Taylor for the suggestion of slate across the
cavity,and thanks to Michael Mcneil for replying to my question about
making a dry mix for screeding.

Yesterday, we made the mix, placed it, but I am now wondering if we
made it too dry!
It compacted in the hand when squeezed, but absolutely no excees
moisture was present.

I wet the slab four times during the day before laying, and PVA'd 5:1
as we screeded.

Even after covering the screed with polythene, the top surface just
became dust, so today I went over the screed with a mist sprayer and
trowelled the surface.
However, it is still suspiciously loose on top.

Should the mix have been wetter, or is it normal for the top to become
a bit loose as it cures?

Is it irredeemable? - am I going to end up needing to seal it or put a
self leveler on to hold it together. Or dig the whole lot out :-(

Thanks in advance

Bill M


too many unknowns Bill, need more info. Mix, depth, just how dry it
was, how well it was tamped, etc

Even at the worst, if its just for domestic use you'd only need to dig
it out if it was loose, otherwise it could just be glued - but
hopefully its nothing like that bad!


Regards, NT

(N. Thornton) wrote in message . com...
(Bill M) wrote in message . com...
Firstly thanks to Mike Taylor for the suggestion of slate across the
cavity,and thanks to Michael Mcneil for replying to my question about
making a dry mix for screeding.

Yesterday, we made the mix, placed it, but I am now wondering if we
made it too dry!
It compacted in the hand when squeezed, but absolutely no excees
moisture was present.

I wet the slab four times during the day before laying, and PVA'd 5:1
as we screeded.

Even after covering the screed with polythene, the top surface just
became dust, so today I went over the screed with a mist sprayer and
trowelled the surface.
However, it is still suspiciously loose on top.

Should the mix have been wetter, or is it normal for the top to become
a bit loose as it cures?

Is it irredeemable? - am I going to end up needing to seal it or put a
self leveler on to hold it together. Or dig the whole lot out :-(

Thanks in advance

Bill M


too many unknowns Bill, need more info. Mix, depth, just how dry it
was, how well it was tamped, etc

Even at the worst, if its just for domestic use you'd only need to dig
it out if it was loose, otherwise it could just be glued - but
hopefully its nothing like that bad!


Regards, NT

Thanks for the quick replies.

We aimed for 3:1 (agg:cement) mix. The aggregate is washed grit (sharp
sand). I specifically mentioned screeding when ordering, it's the
right stuff.

Depth 65 mm.

When laying it on the slab I compacted it underfoot before bringing up
the level with a straight edge across the screeding rails. I used a
plastic float then finished with a steel float.

To my mind it wasn't wet enough to bring the fines up - at all. This
rang alarm bells, but the stuff kept coming in the wheelbarrow - mix
after mix!

I'll give it a slow but more through wetting followed by another steel
trowelling today. It's 36 hours since it was laid, the bulk of it is
solid so if there is any unhydrated cement and small particles I might
just be able to bring them to the surface where they will do some
good. Otherwise I guess I will just have to seal it when cured.

When I screeded the cloakroom I made it too wet. This made it
impossible to level, even in such a small area. Now too dry for the
utility we have just done. Hopefully, should get it right in time for
the kitchen...

Cheers

Bill

(Bill M) wrote in message . com...

I'll give it a slow but more through wetting followed by another steel
trowelling today. It's 36 hours since it was laid, the bulk of it is
solid so if there is any unhydrated cement and small particles I might
just be able to bring them to the surface where they will do some
good. Otherwise I guess I will just have to seal it when cured.

I dont think I'd disturb it after 36 hours myself. Keeping it wet
should maximise its cure strength. I think working it after 36 hrs
would break all the bonds its made.

When I screeded the cloakroom I made it too wet. This made it
impossible to level, even in such a small area. Now too dry for the
utility we have just done. Hopefully, should get it right in time for
the kitchen...

lol, that sounds about normal!

Regards, NT