Unbelievable an *on topic* thread:-)

Is there a time limit between laying oversite concrete and fitting the
insulation, dpc and screed?

Concrete drying time must be similar to screed and there are lots of
warnings about that. Does it matter if the insulation foil is in contact
with moist concrete?
--
Tim Lamb

Logic would suggest that if you have a DPM below the concrete then the only way out for the moisture is through the top surface. I believe curing time for concrete is 28 days.

I have not consulted this site in a while but checking it out may definitively answer your question;

http://pavingexpert.com/

Richard

On 29/09/2019 10:23, Tricky Dicky wrote:
Logic would suggest that if you have a DPM below the concrete then the only way out for the moisture is through the top surface. I believe curing time for concrete is 28 days.

I have not consulted this site in a while but checking it out may definitively answer your question;

http://pavingexpert.com/

Is the OP talking about 'drying' or 'curing'? If it dries out too
quickly it won't be able to cure properly; on the other hand nearly all
concrete is made with more than enough water to make it workable, and
the excess water will need to dry out eventually, depending on where it is.

With ordinary cement 28 days is the 'official' curing time, i.e. nearly
all strength is achieved by then.

--
Max Demian

In message , Max
Demian writes
On 29/09/2019 10:23, Tricky Dicky wrote:
Logic would suggest that if you have a DPM below the concrete then
the only way out for the moisture is through the top surface. I
believe curing time for concrete is 28 days.
I have not consulted this site in a while but checking it out may
definitively answer your question;
http://pavingexpert.com/

Is the OP talking about 'drying' or 'curing'? If it dries out too
quickly it won't be able to cure properly; on the other hand nearly all
concrete is made with more than enough water to make it workable, and
the excess water will need to dry out eventually, depending on where it is.

With ordinary cement 28 days is the 'official' curing time, i.e. nearly
all strength is achieved by then.

It is a *sequencing* issue.

I am constructing a corridor linking an extension to a now cut off
garage. Planning and Building Control kindly allowed the garage to be
used domestically subject to the usual insulation requirements.
For future proofing, the link also needs to meet the regs. hence
underfloor insulation.

It would be convenient to finish the floor before the structure is
weatherproof and before serious frosts arrive.


--
Tim Lamb

On 29/09/2019 10:23, Tricky Dicky wrote:
Logic would suggest that if you have a DPM below the concrete then the only way out for the moisture is through the top surface. I believe curing time for concrete is 28 days.

I have not consulted this site in a while but checking it out may definitively answer your question;

http://pavingexpert.com/

Richard


I always thought proper drying time was a month per inch of concrete,
i.e. longer than you expect.

You can put a secondary dpc on top of the slab.

On 29/09/2019 13:17, Andrew wrote:
On 29/09/2019 10:23, Tricky Dicky wrote:
Logic would suggest that if you have a DPM below the concrete then the
only way out for the moisture is through the top surface. I believe
curing time for concrete is 28 days.

I have not consulted this site in a while but checking it out may
definitively answer your question;

http://pavingexpert.com/

Richard


I always thought proper drying time was a month per inch of concrete,
i.e. longer than you expect.

You can put a secondary dpc on top of the slab.

where then would the moisture go? (I thought that was why DPM above the
slab was an /alternative/ to DPM below it.)

--
Robin
reply-to address is (intended to be) valid

On 29/09/2019 14:07, Robin wrote:
On 29/09/2019 13:17, Andrew wrote:
On 29/09/2019 10:23, Tricky Dicky wrote:
Logic would suggest that if you have a DPM below the concrete then
the only way out for the moisture is through the top surface. I
believe curing time for concrete is 28 days.

I have not consulted this site in a while but checking it out may
definitively answer your question;

http://pavingexpert.com/

Richard


I always thought proper drying time was a month per inch of concrete,
i.e. longer than you expect.

You can put a secondary dpc on top of the slab.

where then would the moisture go?
Doesnt need to go anywhere.
Concrete sort of meeds CO2 to set tho, so its not great hermetically sealed

(I thought that was why DPM above the
slab was an /alternative/ to DPM below it.)



--
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(or environmental activism) is becoming a general ideology about humans,
about their freedom, about the relationship between the individual and
the state, and about the manipulation of people under the guise of a
'noble' idea. It is not an honest pursuit of 'sustainable development,'
a matter of elementary environmental protection, or a search for
rational mechanisms designed to achieve a healthy environment. Yet
things do occur that make you shake your head and remind yourself that
you live neither in Joseph Stalins Communist era, nor in the Orwellian
utopia of 1984.€�

Vaclav Klaus

In message , The Natural Philosopher
writes
On 29/09/2019 14:07, Robin wrote:
On 29/09/2019 13:17, Andrew wrote:
On 29/09/2019 10:23, Tricky Dicky wrote:
Logic would suggest that if you have a DPM below the concrete then
the only way out for the moisture is through the top surface. I
believe curing time for concrete is 28 days.

I have not consulted this site in a while but checking it out may
definitively answer your question;

http://pavingexpert.com/

Richard


I always thought proper drying time was a month per inch of concrete,
i.e. longer than you expect.

You can put a secondary dpc on top of the slab.
where then would the moisture go?
Doesnt need to go anywhere.
Concrete sort of meeds CO2 to set tho, so its not great hermetically sealed

(I thought that was why DPM above the
slab was an /alternative/ to DPM below it.)

Umm. I thought CO2 absorbtion by concrete was an issue for steel
reinforcement rather than a necessary part of the cure.

I put plastic sheet below the concrete to save properly blinding the
hardcore and will put dpm over the insulation.

I can re-plan the work and tarpaulin over the roof to create a tent.

--
Tim Lamb

On 29/09/2019 14:24, The Natural Philosopher wrote:
On 29/09/2019 14:07, Robin wrote:
On 29/09/2019 13:17, Andrew wrote:
On 29/09/2019 10:23, Tricky Dicky wrote:
Logic would suggest that if you have a DPM below the concrete then
the only way out for the moisture is through the top surface. I
believe curing time for concrete is 28 days.

I have not consulted this site in a while but checking it out may
definitively answer your question;

http://pavingexpert.com/

Richard


I always thought proper drying time was a month per inch of concrete,
i.e. longer than you expect.

You can put a secondary dpc on top of the slab.

where then would the moisture go?
Doesnt need to go anywhere.
Concrete sort of meeds CO2 to set tho, so its not great hermetically sealed

No it doesn't. That's lime mortar. Portland cement sets if sealed or
underwater. There's just the issue of whether the excess water in the
mix could cause a problem.

--
Max Demian

On Sunday, 29 September 2019 10:03:42 UTC+1, Tim Lamb wrote:
Unbelievable an *on topic* thread:-)

Is there a time limit between laying oversite concrete and fitting the
insulation, dpc and screed?

Concrete drying time must be similar to screed and there are lots of
warnings about that. Does it matter if the insulation foil is in contact
with moist concrete?
--
Tim Lamb

Concrete doesn't set by "drying" (it will set underwater.)
A non-linear chemical reaction takes place.
You need to wet concrete down as is sets.

Chemicals in wet concrete will attack aluminium foil (strongly alkaline). You can buy a plastic film to put down to separate the two.

https://www.concreteconstruction.net...ect-concrete_o

Would not a dpm just under the slab tend to wear out rather fast letting all
those problems reoccur?
Brian

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"Robin" wrote in message
...
On 29/09/2019 13:17, Andrew wrote:
On 29/09/2019 10:23, Tricky Dicky wrote:
Logic would suggest that if you have a DPM below the concrete then the
only way out for the moisture is through the top surface. I believe
curing time for concrete is 28 days.

I have not consulted this site in a while but checking it out may
definitively answer your question;

http://pavingexpert.com/

Richard


I always thought proper drying time was a month per inch of concrete,
i.e. longer than you expect.

You can put a secondary dpc on top of the slab.

where then would the moisture go? (I thought that was why DPM above the
slab was an /alternative/ to DPM below it.)

--
Robin
reply-to address is (intended to be) valid

If done properly the oversite is stable, is topped with compacted
crushed stone or the like, and blinded with fines. So there's nothing
to move which could "wear out" the DPM.

From the little I see of ground work around here I can see why some
prefer block and beam

On 30/09/2019 09:00, Brian Gaff wrote:
Would not a dpm just under the slab tend to wear out rather fast letting all
those problems reoccur?
Brian



--
Robin
reply-to address is (intended to be) valid