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< prev - next > Energy Hydro power Layout_and_construction_of_canals (Printable PDF)
d) Removing the wooden frames
These are usually removed after 24 hours (in cold climates). So that they
are easier to remove, a layer of petroleum or burnt oil should be spread
on them before lining the canal; this will also help to keep them clean and
in good condition. When removing the wooden frames, care should be
taken to prevent the outside borders from deteriorating.
e) Curing the lined canal
Fresh concrete should lose its dampness slowly so that it hardens to the
desired resilience, to which end it must be cured by filling the lined boxes
to the brim with water for at least 10 days.
This is easy to do, placing turf at the ends so that the water fills the lined
boxes. Excess water can be eliminated through a provisional overflow
pipe upstream.
In this way, the water route can be followed and the slope verified.
The curing must be done carefully as it is very important.
f) Filling in the expansion joints
The expansion joints will be determined by the spaces left by the wooden
frames when they are removed, every 2.50m in straight sections and
variable on a curved section. This will allow the concrete to expand or
contract depending on the temperature, thus preventing the boxes from