Copper pipes buried in concrete

[gasgas]

My daughters house has all the copper CH pipes buried in the concrete floor, so of course they are corroded and leaking. I have replaced the copper with plastic, but where the copper pipes disappear into the brick room dividing walls I can't do that without removing bricks, which I don't want to do.
How do I isolate the remaining few inches of copper pipes where they go into the brickwork before I refill the trenches with mortar? Does builders foam react with copper over the long term, or do you have any other suggestions?

 

[AlanE]

Plastic tube slit lengthwise and fed onto pipe?

 

[Nozzle]

http://www.toolstation.com/shop/p72819

Nozzle

 

[gasgas]

Thanks Alan and nozzle. I call that stuff gunge tape. I did think of it, but on the first job I did at this house I didn't think it was feasible for some reason. Anyway on the second occasion, because of the expense of the electrical insulation gel I used the first time, I have used gunge tape. I couldn't wrap it round of course as the pipes are buried in concrete so I dug out as much as I could and cut strips of gunge tape and laid it lengthways. Two strips overlapping easily cover a 15mm pipe. I am satisfied with the result, I am sure it won't deteriorate any more. I think the cement had got through some weak points in the rubbish horse hair / polythene wrapping the installer used.