As so much concrete
is required in a concrete dam, it is mixed together in a special
building called a concrete batching plant, which is built
on the construction site. For very large dams, there may be
a number of batching plants. The concrete can be placed in
the dam by two different methods.
A concrete batching plant on the
construction site for a gravity
dam
Pouring Concrete
The traditional method is to pour a
wet mixture of concrete into a mould made in the required shape
of the dam. The mould, called formwork, is usually made from
sheets of timber. The mould is not made to the full height of
the dam, as the dam is built upwards in stages of about 1 to
2 metres at a time. The concrete is left to dry before the next
section is formed on top.
The concrete can be transferred from the
batching plant to the dam by a number of methods. Sometimes,
a system of conveyor belts is used and sometimes the concrete
is taken by trucks to the bottom of the dam where it is poured
into skips which are lifted to the top of the dam by cranes.
Compacting
Concrete with Rollers
Roller
Compacted Concrete (RCC) dams are formed by spreading
a drier of mix of concrete and compacting it down using rollers.
The dam is raised in steps of about 600 mm. The edges are formed
first, by making low concrete walls on the upstream
and downstream
faces of the dam. Concrete is then transported to the area between
the walls and spread in a thin layer using bulldozers. Rollers
are then driven over the concrete to compact
it down.
Concrete being placed and compacted
on Stillwater gravity dam in the
United States
