The3rd Earl Of Derby wrote:
Brian G wrote:
Grumps wrote:
Hi All

I read an article saying that copper will resist corrosion if laid
in a portland based concrete or mortar. Could someone explain why,
and what is the alternative to portland that WOULD corrode copper?
(Sorry, my knowledge of chemistry never was a strong point).
Ta.

Grumps,

Don't lay copper pipes in concrete full-stop. They will eventually
corrode even if plastic sleeved. Where the pipes are joined (and
there will be joins), you will find it difficult to seal and the
'fat' of the concrete will find its way onto the pipe causing the
said corrosion.

There is a small council housing estate near to where I live with the
CH pipes buried in the concrete and after about 10 years, these
started to leak causing me to have a few grey hairs in trying to sort
it out - the only cure was to re-pipe all the systems above floor
level. BTW, most cements used in these conditions are OPC (Ordinary
Portland Cement)

If you MUST lay pipes in concrete, consider using plastic - if want
my opinion - don't even do that!


Brian G

This has been asked sometime ago, however I used to live on a housing
estate 35 years ago and to this day the pipes are still buried in the
concrete...Gas copper pipe I might add. (Mothers House)



All I can say is what I experienced on this particular site. The houses
were built in the 70 - 80's and are of a No-Fine concrete construction with
a standard concrete base with a 2" screed/tiled finish with the plastic
sleeved copper pipes buried between the both.

The problems first arose around the end of the 80's with damp patches
showing on the floor in just one house. When the pipes were exposed,
corrosion was found around the area of the pipes that were joined using
end-feed soldered fittings which had NOT been very well protected after this
was done.

When we investigated further, pipe corrosion was found upto a foot a way
from the fitting and UNDER the protective sleeve (the ends of this having
been softened when heat was applied to the joints) - which indicated that
some of the 'fat' from the screed/concrete had somehow founds its way under
the sleeve.

After this problem raised its ugly head in about 10 or 12 properties (with
the resulting insurance claims by the tenants), it was decided to fit new
heating systems and bring all of the pipework above floor level.

With regards to the "Gas copper pipe" you were talking about. If I remember
this came in very long rolls of copper with a yellow plastic sleeve, I would
presume that this was laid 'joint free' thus leaving the sleeve intact over
its entire buried length - in our case, the heating pipes were of standard
lengths and then jointed as needed. And that WOULD make a difference.



Brian G