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The concrete is poured in on top of the drainage layer and lightly
rammed with a wooden block when the form is half full; then reinforcements are set, and the rest of the hole is filled and lightly
tamped to release air bubbles. The screed board or the trowel and the
float alone may be used to level off the concrete with the surface of the
soil. You may prefer to use freeform or simulated "crazy-paving" forms
rather than squared forms for your stepping stone or paving. They will
look more natural if you striate or lightly brush and roughen the surface
of the concrete, and will be less dangerous underfoot in wet weather
than if they had smooth surfaces.
If you want your stones colored, you can mix two batches of concrete.
With the natural batch fill the forms half way and then, on top of the
reinforcements, pour the colored concrete layer and finish it as described.
. . . what size for the stones?
If blocks are to be used for stepping stones, the size is largely a matter
of individual preference, but will also be governed by the distance
from center to center of the stones. As they are finally laid they should
be comfortable for the average adult to use. 12 to 18 inches center to
center is a good average for the casual garden stroller. If, on the other
hand, the blocks are to be used in a pattern (see paving section Chapter
XVI) on a terrace or a walk, then they must be worked out carefully
to an exact modular size so that they can be easily fitted together when
they are laid. In this case the usual ratio is 2 to 1-that is, the length
equals twice the width. Make the length about 1/4 to 1/2 inch longer than
the exact double measurement of the width to allow for joint spaces between blocks when they are finally laid.
Blocks larger than 16X32 inches are practically impossible to transport, and are unwieldy and heavy even if they must be moved into place
nearby. The maximum size we recommend is 12X24 for a 3-inch thickness. These may be placed on rollers and guided into the place where
they are to be permanently set; then shifted a little with a crowbar for
final placing. Blocks smaller than the above sizes can be increasingly
easily handled.
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