On 16 Jul, 13:38, (Anna) wrote:
On Mon, 16 Jul 2007 05:06:42 -0700, Fash
wrote:



On 16 Jul, 12:42, wrote:
On 16 Jul, 10:20, "TMC" wrote:

wrote in message

ups.com...

Hi

I'm considering laying a limecrete patio slab. I'm considering it for
2 reasons:

1. I have neither a damp proof course nor damp proof membrane in my
house, and I'm concerned that a concrete slab next to it might cause
some damp.

2. Sometime in the future, I may be able to afford a little
conservatory on it, so I might as wall do the slab now while I'm
working on the patio anyway.

I'd rather not risk causing damp, but I'd also rather not risk the
slab not setting. I may end up putting a very small amount of cement
in the otherwise 6 ballast to 1 hydrated lime mix.

Any thoughts?

T

Never even looked at limecrete before so Googled out of interest

I was not even considering replying to your post

However Google turned this uphttp://www.oldhousestore.co.uk/tech_ohs/limecrete.html

which I thought may be of interest

Tony

Thanks for the link. Unfortunately they did not test the cheap stuff,
ie. bagged hydrated lime. I have experimented a bit with it in mortar
form, and it seems to go off eventually. I'm also not bothered how
hard the limecrete sets - so long as it doesn't break up.

I suppose an alternative would be to leave a reasonable gap between a
concrete slab and the house, and fill it with pea shingle or
something.

T

That's because the cheap stuff is rubbish. Bagged hydrated lime
generally contains a significant amount of already calcified material
which will affect the final quality.

I have not laid limecrete so talking off the top of my head ...

I dont think damp need be a problem in this situation. Angle the slab
to drain away from the house

Either make the slab with cement or for a lower carbon footprint make
it with hydraulic lime. If your old floor is hydraulic then its good
to have the same so they move in unison ... hm, not that floors tend
to move much ...

Hydrated lime is not suitable for this situation, which is exposed,
damp and will get hard wear

Anna

I'm not so much concerned with drainage as condensation. If I leave a
plastic mat on the floor of my house, it gets slightly damp
underneath. If I cover the floor with plastic (done by previous owner)
then enough condensation builds up over the years to drive damp up the
walls. Not a lot of damp, but I prefer none at all. I'm just a bit
concerned that concrete might do the same but from the outside. The
limecrete slab does not have to be hard wearing, as I will pave it
with a natural stone.

I'm not sure what the problem would be with using bagged hydrated lime
so long as it's fresh. From what I've tried so far, it sets in a
couple of weeks, and you can speed that up by adding a little cement.

T