Copper waterstops on late 1960's water retaining structures

[VeVan93]

Hi, I am currently looking into the condition assessment of a Surge tank build in 1968. We found one particular location that has some sort of copper colour efflorescence around a set of stairs. These stairs were cast above a header pipe. I believe that the pipe might be "sweating" and this condensation could be coming through the construction joints around the stair pour. The As-built drawings show that the waterstops on this facility are made of steel.
-Is there a chance that a building of this age has copper waterstops instead of steel and this might be the cause of the odd copper colour efflorescence?
-Those anyone has an idea of the timeframe in which copper waterstops were common as a construction material for water retaining structures?

 

[HTURKAK]

Copper colour efflorescence does not mean there , waterstops are copper instead of steel. This implies , the reinforcement corroded and the migration of iron oxide to the surface of the concrete surface. The use of copper waterstops was before 80's.. Nowadays, PVC or LDPE waterstops are in use.

Pls provide some pictures and and as built details ( if available ) for the mentioned concrete stairs to get more useful responds..

 

[VeVan93]

Hi HTUKAK,

Thanks for the reply here is a picture of the are discussed and a snap of the area per record drawings. As you can see the there is some efflorescence around the stairs I am not worried about the dark blue spots(those are just soaked racks left there by a previous contractor) but more of the lighter blue area (looks like copper oxide). I apologize for the lack of clarity on my previous thread as I did not clarify the specific colour and might lead to think a brown/red colour, more typical of corrosion of carbon steel material.

 

[LittleInch]

Well first I think you need to jet wash the concrete to get rid of all the surface gunk before you even know if there is any water or discharge form the pipe itself. Looks too blue to me and more like some sort of chemical or spillage from a tin stored there.

"sweating" is only possible if it's open to atmosphere and able to get condensation or the pipe is porous.

Doesn't look possible to me and if anything was leaking out surely it would end up in the void under the floor?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[VeVan93]

Thank you LittleInch, I scrapped the efflorescence on the side opposite to the gunk. The area looked fairly damped under the efflorescence. That's what leads me to believe that there is some sort of moisture transfer from under the stairs; might be the pipe, might be the soil. These stairs were not monolithically poor as cracked construction joints are typical all around them.

 

[r13]

I think more than moisture, the water mark indicates there was seepage under the stair pad.

 

[HTURKAK]

The pipe installed more than 50 years ago... and apparently leaking..The diameter seems to be 72 in. IMO, a corrosion survey shall be conducted and remaining life of the pipe should be investigated. The remaining life and fitness for service assessment could be conducted as per ASME B31G Manual for Determining the Remaining Strength of Corroded Pipelines and The recommended practice API RP 579.

IMO, The blue efflorescence around the stairs is not related with pipe or any waterstop..

The steel pipe exterior coatings for that years was coal tar or bitumen and the interior coating could be cement lining... My suggestion will be, before repairing the pipe , abandonment of existing system and renewal should be considered .

 

[r13]

Check the dryness of the wall behind the ladder, there may have a leak somewhere above.