You could also slide the copper pipe through a length of PVC waste pipe thus making a sleeve to protect the copper from the acid in the concrete. If you need to bend the copper pipe then use glued PVC bends to allow the PVC to bend with the copper pipe.
This method will allow access to the easier removal of the copper pipe should a leak occur in the future.
We bring the PVC pipe up through the concrete to about 100mm (4 inches) above the concrete level and wrap the gap with tape to stop anything falling down the duct.
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians