Anyone know of any reason why copper cannot be embedded in concrete due to an interaction? I did a google search and found the article below, and they say No problems whatsoever, just allow for thermal expansion at the point of contact. What say you?
Seems to me that they would be an authority on the product. Works for me, unless restricted by another pertinant authority (AHJ).
I assume that you read the entire page as there is a restriction towards the bottom.
As an inspector, how would we know what the concrete was mixed at? I think if cooper is not sleeved, I will keep on calling it out
We wouldn’t, but based upon this statement…
…unless it was a fresh pour, we should be able to see some indication of an issue developing.
FYI… whenever I see copper water supplies, which is becoming very common in new construction around here (last 5-10 years), I almost always see it wrapped/protected, but not sleeved. I have yet to see any interaction from the concrete. Corrosion at the main valve… 12-18 inches above floor… almost always.
Not saying we shouldn’t be cautious, but I have not seen any problems… yet!
I have heard that ancient heating systems (Ancient meaning 40’s and 50’s) In floor heating with copper and concrete have largely been abandoned due to leaks. Having read this article, I would lean toward the side that they leaked due to shifting concrete, rather than concrete/copper interaction. Unless there is something different in the alloys of the day vs now. Copper is Copper.
No actual case study here, just expanding my head knowledge. My wife would call it expanding my head.
I always thought the reason why they corroded was a mixture of the chemicals in the concrete and the air exposure, similar to what rust does. Rust seems to show the most signs of deterioration at the water line.
I did not go to the web site but from your post it sounds right on for copper piping. With that said it is not neccesary to isolate copper grunds or bonds as copper does not react with concrete. here in florida 99.99% of the homes are built utilizing a monolthic slab and the electric services are bonded to the reinforcment steel without isolation, also the expotential bonding of pool decks is done in the surronding concrete decks with bare copper wire. food for thought
The statement “However, copper should be protected when it comes in contact with concrete mixtures that contain components high in sulfur, such as cinders and fly-ash, which can create an acid that is highly corrosive to most metals including copper” is the answer.
Every concrete mixture I have seen has fly ash unless you specify “no admixtures”. Even then they will sometime add it. BTW that applies to Texas, Ohio and Florida that I am familiar with.
I have copper embedded in concrete for plumbing at my place that has been there for decades with no issues.
How about all those main lines everywhere?
Should not be an issue.
This may help.
Is There A Problem With Embedding Copper Tube In Concrete?
It is completely acceptable to bury/embed both hard drawn and annealed copper water tube in concrete. Decades of satisfactory service experience with the use of copper tube for in-floor radiant heating systems, water distribution systems and snow melting systems attest to the compatibility of copper tube embedded, encased or in contact with concrete
The copper tube must be completely embedded in the concrete and adequate provision for thermal expansion should be provided where the tube enters/exits the concrete.
It is also acceptable to run a copper water tube through a concrete floor or wall, provided that allowance is made for the lateral thermal expansion and movement of the tube and protection of the tube from abrasion. This can be done by insulating the tube where it passes through the wall or by wrapping the tube with an approved tape (to avoid abrasion) and installing it through a sleeve. Please refer to your local plumbing code for specific requirements regarding the protection of pipes and tubes passing through concrete and masonry floors and walls.
Both of the protection methods outlined above and the requirements listed in most plumbing codes are simply to protect the copper tube from the fatigue and wear caused by thermal expansion and movement. These protective measures are in no way dictated by the interaction of the concrete and the copper tube.
According to the Portland Cement Association the interaction of copper with both dry and wet concrete should not cause a corrosion concern. However, copper should be protected when it comes in contact with concrete mixtures that contain components high in sulfur, such as cinders and fly-ash, which can create an acid that is highly corrosive to most metals including copper.
A screened soil/pulverized limestone mixture is recommended as a selective backfill for copper tube to help eliminate corrosion concerns.
For more information on this topic, please review the following articles:
Corrosion of Embedded Materials Other Than Reinforcing Steel
Corrosion of Non-ferrous Metals in Contact with Concrete
Burying Copper Tube in Concrete or Mortar and Thermal Expansion Allowance
Corrosion of Copper and/or Iron Embedded in Concrete or Plaster
The problem that I’ve had first hand experience with is…the copper piping (that was embedded in concrete floor) was leaking exactly where the reinforcing rebar was pushed up against the embedded copper pipe during the original pour.
I performed an IR scan at a local hotel who was having problems with leaking embedded pipes. They hired me to pinpoint the leak in the hot water supply line that was embedded in their concrete floor.
Here’s my IR images…
The plumbers showed up (after I pinpointed the area of the leak) and they opened up the floor and found this…
The blueish areas are the areas where water was seeping out of the pipes. As they were jackhammering these areas and pulling out chunks of concrete, we found sections of rebar sitting right on top of the copper pipe itself. The galvanic reaction of the rebar caused this mess.
If embedded copper pipes are protected from rebar being weighted down on top of the copper pipes, there shouldn’t be issues.
Nice tool indeed Dave.
I have a stupid question on the pictures.
Why is there scored lines in the floor with the hoses and puddle of water and the cut-out picture dosen’t and looks like a monolithic terrazo?
Just curious. :)
This is the kitchen of the hotel. The scoring you see is a thin non-skid coating (like an epoxy) that the original installers applied to the floor. I believe they simply scored it to make it look like floor tiles.
The cut-out picture does contain the same scoring if you look real good, you’ll see the lines.
Thanks Dave, that’s what I thought, but sometimes a picture dose no justice on details.
By the way, how many other areas is this problem bound to happen again?
Wire mesh or re-bar is bound to be touching the pipe in other areas.
That camera is something else.
Wish I had one, but wish I had a job too! :mrgreen:;)
This pic is a top view. Note the scored lines at this guys foot…
Good point. The hotel management had me thermally scan the entire first floor and I did find additional anomalies.
They had these areas breached and repaired the pipes just as they did in the kitchen.
Here’s another one in front of the hotel rooms…
This is an IR image of the hallway (in front of the rooms) with no anomalies…
Note the individual supplies going right across the hallway.
They do plan on abandoning the embedded hot water supply system in the near future, but until then…they have me contracted to evaluate/monitor this system four times a year.
Yep, see it.
What a mess that made huh!
Probably will happen somewhere else.
That’s why I’m contracted to thermally scan this floor every four months, until they abandon this hot water supply system.