On 31 May, 15:56, Tim Watts wrote:
On 31/05/10 13:21, sm_jamieson wrote:



On 31 May, 13:06, Tim *wrote:
On 31/05/10 12:16, sm_jamieson wrote:

On 31 May, 11:38, * *wrote:
On 30 May, 09:32, Tim * *wrote:

On 29/05/10 23:00, sm_jamieson wrote:

Whats the process and quantities to mix SBR screed then? I have a
belle mixer that needs a good clean out !
Simon.

Copy of data sheet sent to your hotmail address - if that's not valid,
please email me one that is

--
Tim Watts

Hung parliament? Rather have a hanged parliament.

Thanks, got it.
Simon.

So it looks like half water, half SBR.

IIRC, that's the one...

How did you mix it ?
Looking at their website it seems like you need a special
forced action mixer.

Nah - normal mixer is fine. However, they do mention that air
inorporation may be a problem. So I mixed the ingredients dry, then
added the liquid (premixed SBR/water) and mixed for the minimum time to
get it right.

Fill the mixer with water as soon as you dump the load though, and leave
it turning, or you'll never get the SBR off.

Slurry I mixed with a spoon in a bowl and applied with a large
paintbrush as I went.

--
What consistency should you aim for - dry as possible as for plain
sand/cement screed, or a little bit wetter ?

I had a labourer helping who'd done dry screeding before. We mixed
according to the data sheet, which to me seemed very dry and to him
seemed normal (so he said). However, it acted like it was wetter. Now,
I'd gone with a plan of screwing level battens to the wall and using a
2x4" taper bar with "ears" screwed on the ends at the top so that when
the ears rested on the wall battens, then the tamper would tamp to the
correct level. This turned out to be a good idea (though a bit alien to
my employee) as the screed acted wetter than it was (there are warnings
to this effect, if not in your data sheet, then one of the other
manufacturer's).

So if you are planning to screed the old fashioned way by running screed
round the edges of the room, then infilling, you might want to make it a
notch dryer than you think. OTOH, if you are going to splat it on and
screpe it level, then float it off (the sort of thing I'd do 'cos I
can't do screeding the proper way) then I think you'll find the mix OK
if done by the sheet. It trowells well with a steel float, and it
behaves quite well with tamping and scraping off (rather like a *very*
viscous plastic mass).

The other thing they mention is cleaning the concrete base first (they
say shot-blasting etc !!!). One area of base was poured last week, the
other is 2 years old. Did you prepare the base first ?
I could wash the lot with brick acid first I guess.

I didn't bother. Onto old concrete, I hoovered with a VAX to remove
excess dust and crap, then poured SBR/water in a 1:4 (that's on the
sheet) and brushed it in to saturation. That will bind up anything loose
in the surface. This can be left to dry as long as you like, or done the
day before. The cement/SBR slurry will need to be applied as you go so
it maintains a wet interface to the screed and that will bond the screed
to the concrete in a highly reliable way.

The only thing I would to is ensure you don't have large areas of
bitumen on the surface, should you have just peels tiles or wood parquet
off - even SBR doesn't like bitumen.

Also (sigh) I need to clean out my cement mixer. Its a bit encrusted
at the moment, and I'm sure you want it smooth and clean so the stuff
slides out happily !

Mine's not that clean. It was second hand, and I did take an SDS to it
to take of the thicker crap - but it is most certainly not gleaming
steel. Don't worry about that - the SBR screed will plop out OK. It's
leaving SBR screed in it that's the problem - you will not shift that
half as easily.

Beware of the ground you dump the mixer cleaning water on too - I
managed to make my lawn go like plastic afterwards. Raking out a small
ditch next to the mixer to contain the washings might be an idea if you
have a fine garden. Don't dump the washings on your block drive or it's
liable to go shiney. SBR is amazing stuff at not coming off.

Sounds like you'll need a fair quantity. You can get it in 25l cans for
about 70-80 quid all in. I got mine from here by internet:

http://www.permagard.co.uk/index.php...info&products_....

They were fast when I last ordered (3 days IIRC).

Cheers,
Simon.

Have white spirit and wire wool handy to clean anything metal like the
float - if it sets on your tools, white spirit works.

Can't remember who put me onto SBR, but it was here. I've been using it
for all manner of floor work since and in particular patching loose screed.

http://photos.dionic.net/v/public/bu..._0018.jpg.html

In that, the light grey areas are SBR screed patching to infill deep
damage. The brown is the original very weak screed - wasn't weak by the
time I'l poured some 4-5 gallons of SBR/water over it - twice!. The
patching screed was to save on the rather expensive StopGap 900 that was
going on top, and also to keep the Stopgap 900 within its limitation of
depth. The SBR screed was typically 10-20mm thick and feathered at the
edges, but testing with a chisle showed that it had bonded perfectly to
the crap underneath. Even teh concrete wasn't that strong. The floor is
now tiled with slate and is showing no signs of being unhappy.

I did the daughter's bedroom and the bathroom as a full rescreeding job
down to concrete - using SBR as the thickness was about 30mm and also as
an aid to holding back damp (we have a patchy DPM in this house - it's
old). In that respect it seems to work.

Good luck

Thanks, excellent information.
I think the SBR screed might be good at doing the floor in stages /
since it will all stick so well. Perfect for my needs.
I'll let you know how it goes - probably not doing it for a few weeks.
Simon.