BUILDING FOUNTAINS AND PONDS - Garden
Pools and Fountain 9
Large pools of this kind are somewhat
easier to make. Sides about 10 in.
thick and extending 12 to 15 in. into
the soil are made first by
pouring concrete in a form. If the soil
stands firm, it can serve as
the outer wall of the form. Otherwise
a two-walled form
is required. A 1:3:5 concrete mix is
adequate, and reinforcing in
the sides is usually not required. Preferably
the forms should not
be removed for a week, but, if it is
necessary in order to speed con-
struction, they can be taken off in 48
hours. The walls can be built of stone
laid up in mortar without the use of
forms. The thickness may be increased
to suit the dimensions of the available
stone.
If the soil of the site is porous, particularly if
it is gravelly, the
base for the bottom can be prepared simply by raking
it to the shape
desired and then tamping it well. However, if the soil
is a tight one,
it should be excavated down to the bottom of the footings.
The ex-
cavation is then filled in with gravel or coarse cinders.
These are
raked into the desired shape and are compacted by wetting
and
tamping.
After the base has been prepared, the concrete reinforcing
mesh
is cut to fit the excavation and is laid on it. Holding
it away from
the base is not essential because it can be pulled
away as the concrete
is placed. Enough workmen should be on hand so that
the concrete
can be placed rapidly and without halting operations.
For a pool 10
ft. in diameter, at least two workmen are used. A 1:
21/4: 3 concrete
mix which contains no aggregate coarser than 3/4 in.
in diameter
should be satisfactory. Placing of the concrete should
begin at the
center. The mesh is lifted at a few points and several
small trowel-
fuls of concrete are worked under it to give it support.
The concrete
is then placed all over the raised area and is smoothed
with a large
trowel or small float. The workmen then back up, raise
more of the
mesh, and repeat the process while taking care to keep
the concrete
well-joined at all points. When the outer edges are
reached, the
workmen retreat to the ground around the pool and lean
over the
edge to finish. The joint between the bottom and the
sides should
be made as well as possible, but water-tightness cannot
be achieved.
The concrete lining should be covered with damp straw
or other
material that will hold water and the lining damp-cured
for seven
days.
The asphalt coating should be applied according to
the manufac-
turer's directions. Two types of asphalt preparations
are suitable:
those designed for mopping on while hot, and those
designed for
cold application. A preparation intended for hot application
can
usually be applied only by a contractor who owns the
necessary
heating equipment. Preparations for cold application
are usually
applied in the following way: the concrete is swept
thoroughly, and
then washed clean. The asphalt is then applied by brushing
or
spraying. The pool should be ready for use after application
of the
asphalt has been completed.
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