As most of you know, I have a very crappy front room floor, half of which
is "screeded" with a very weak mix.

A few weeks ago I soaked 10l of SBR mixed with 30l of water into the floor
until it could take no more (20m2).

Yesterday, I was patch-screeding to fill in the deeper holes where I'd
removed loose screed. I had to chisel a little bit more out to clean up the
edge of a hole, so I took the chance to see what the SBR had done.

Result - on a 1/2" thick lump 3" back from the edge, there was a strong SBR
film on the top and the rest of the lump was consistently tough all the way
through. I don't think much SBR had made it to the concrete below, but the
previously friable screed is now pretty solid. Took a reasonable amount of
SDS effort to shift it. Not as much as a strong screed but a lot more than
would have previously been required.

I'm more than happy pouring scunge on to of that lot. I shall do a test pour
of a small amount to check Stopgap 900 adhesion to the SBR film (it's not
something F Ball have tested) but as 900 is an acrylic mix, I don't expect
any problems.

I also mentioned previously that the humidity had dropped sharply in the
room after the SBR set (we know there is no DPM). I did a very crude
measurement the other day. Room humidity was 45% (Oregon weather meter). I
put the Oregon on the floor and covered with an upturned metal bowl
overnight. In the morning, max humidity under the bowl had registered 65%.

That would seem to indicate that the SBR had not blocked the vapour flow but
has probably slowed it considerably. I only have one Oregon, so for all I
know the room humidity might have gone up overnight too, I would have
expected a seriously damp floor to register 80% at least.

Cheers

Tim

Tim S wrote:
As most of you know, I have a very crappy front room floor, half of which
is "screeded" with a very weak mix.

A few weeks ago I soaked 10l of SBR mixed with 30l of water into the floor
until it could take no more (20m2).

Yesterday, I was patch-screeding to fill in the deeper holes where I'd
removed loose screed. I had to chisel a little bit more out to clean up the
edge of a hole, so I took the chance to see what the SBR had done.

Result - on a 1/2" thick lump 3" back from the edge, there was a strong SBR
film on the top and the rest of the lump was consistently tough all the way
through. I don't think much SBR had made it to the concrete below, but the
previously friable screed is now pretty solid. Took a reasonable amount of
SDS effort to shift it. Not as much as a strong screed but a lot more than
would have previously been required.

I'm more than happy pouring scunge on to of that lot. I shall do a test pour
of a small amount to check Stopgap 900 adhesion to the SBR film (it's not
something F Ball have tested) but as 900 is an acrylic mix, I don't expect
any problems.

I also mentioned previously that the humidity had dropped sharply in the
room after the SBR set (we know there is no DPM). I did a very crude
measurement the other day. Room humidity was 45% (Oregon weather meter). I
put the Oregon on the floor and covered with an upturned metal bowl
overnight. In the morning, max humidity under the bowl had registered 65%.

That would seem to indicate that the SBR had not blocked the vapour flow but
has probably slowed it considerably. I only have one Oregon, so for all I
know the room humidity might have gone up overnight too, I would have
expected a seriously damp floor to register 80% at least.

Cheers

Tim

The main feature of SBR is its small molecule size compared to pva, so
it mimics the behaviour of a solvent based product. The slight downside
is that in a mortar mix the bulk of it tends to take off on its own into
the substrate, but that's beneficial in a screed .
Difficult to get off your hands too, as I'm sure you've discovered by
now :-)

Stuart Noble wrote:
Tim S wrote:
As most of you know, I have a very crappy front room floor, half of
which is "screeded" with a very weak mix.

A few weeks ago I soaked 10l of SBR mixed with 30l of water into the
floor until it could take no more (20m2).

Yesterday, I was patch-screeding to fill in the deeper holes where I'd
removed loose screed. I had to chisel a little bit more out to clean up
the edge of a hole, so I took the chance to see what the SBR had done.

Result - on a 1/2" thick lump 3" back from the edge, there was a strong
SBR film on the top and the rest of the lump was consistently tough

The main feature of SBR is its small molecule size compared to pva, so
it mimics the behaviour of a solvent based product. The slight downside
is that in a mortar mix the bulk of it tends to take off on its own into
the substrate, but that's beneficial in a screed .

Sounds very handy, must buy some - is this the stuff?
www.wallsandfloors.co.uk/acc-details.php?aid=318

Stuart Noble coughed up some electrons that declared:


The main feature of SBR is its small molecule size compared to pva, so
it mimics the behaviour of a solvent based product.

That explains a lot.

The slight downside
is that in a mortar mix the bulk of it tends to take off on its own into
the substrate, but that's beneficial in a screed .

Yes - I of course patched with an SBR 4:1 screed as it's only 15mm thick.

Difficult to get off your hands too, as I'm sure you've discovered by
now :-)

SS wire scourers work!

In fact scouring the float and trowels is the only way to clean the sodding
stuff off. I have a stainless metal bowl that I use for the cement/SBR
slurry and that has a layer of SBR+cement that won't come off with any
amount of scrubbing and banging - so it has provably excellent adhesion.

It *is* the new PVA for me

BTW - What is it like regarding adhesion to it by other things, say a few
weeks after it's dried?

It was slightly tacky for a week, but not any more. I was wondering to brush
on another thing layer the day before pouring the Stopgap...

Cheers

Tim

Steve Walker coughed up some electrons that declared:

Stuart Noble wrote:
Tim S wrote:
As most of you know, I have a very crappy front room floor, half of
which is "screeded" with a very weak mix.

A few weeks ago I soaked 10l of SBR mixed with 30l of water into the
floor until it could take no more (20m2).

Yesterday, I was patch-screeding to fill in the deeper holes where I'd
removed loose screed. I had to chisel a little bit more out to clean up
the edge of a hole, so I took the chance to see what the SBR had done.

Result - on a 1/2" thick lump 3" back from the edge, there was a strong
SBR film on the top and the rest of the lump was consistently tough

The main feature of SBR is its small molecule size compared to pva, so
it mimics the behaviour of a solvent based product. The slight downside
is that in a mortar mix the bulk of it tends to take off on its own into
the substrate, but that's beneficial in a screed .

Sounds very handy, must buy some - is this the stuff?
www.wallsandfloors.co.uk/acc-details.php?aid=318

Yes, but that's an expensive way of buying it (but no worse than walking
into Travis Perkins - they *will* ass rape you.

If I can plan forward enough and need more than 5l, I buy from

http://www.permagaurd.com/

Otherwise:

http://www.google.co.uk/products?hl=...=hp&q=sbr&q=5l

Indicates the average price is 12-15 quid - but delivery varies.

Tim S wrote:
Stuart Noble coughed up some electrons that declared:


The main feature of SBR is its small molecule size compared to pva, so
it mimics the behaviour of a solvent based product.

That explains a lot.

The slight downside
is that in a mortar mix the bulk of it tends to take off on its own into
the substrate, but that's beneficial in a screed .

Yes - I of course patched with an SBR 4:1 screed as it's only 15mm thick.

Difficult to get off your hands too, as I'm sure you've discovered by
now :-)

SS wire scourers work!


In fact scouring the float and trowels is the only way to clean the sodding
stuff off. I have a stainless metal bowl that I use for the cement/SBR
slurry and that has a layer of SBR+cement that won't come off with any
amount of scrubbing and banging - so it has provably excellent adhesion.

It's actually classed as a synthetic rubber I think, although it would
be at the non-flexible end of the spectrum.

It *is* the new PVA for me

BTW - What is it like regarding adhesion to it by other things, say a few
weeks after it's dried?

Dunno. It certainly sticks to itself and takes paint well.
I use it for shallow repairs to mortar where thin coats wouldn't
normally take.
I keep meaning to cast a garden trough with it to see how flexible it
really is.

It was slightly tacky for a week, but not any more. I was wondering to brush
on another thing layer the day before pouring the Stopgap...

Cheers

Tim

The message
from Tim S contains these words:


Yes, but that's an expensive way of buying it (but no worse than walking
into Travis Perkins - they *will* ass rape you.

I seem to have escaped that fate over the last 30 years.

Often the cheapest place around here to get sheet goods on site. And
they'll deliver free -- even 100 miles away from the depot, provided
you're an account holder. Used discerningly, I've found them OK.