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Make at least two forms; half a dozen or
more will be none too many if you plan to use many blocks for paving.
Fewer than that will make it hardly worth while to mix up a batch of
concrete for the casting. Perhaps you will want a dozen forms when you
get the hang of how they can be used and get your project running well.
Before casting the blocks, brush the forms with old crankcase oil
saved from an oil change in your car. Any sort of oil or grease can be
used, so long as the forms are thoroughly brushed with it before each
casting to prevent the cement's adhering to the wood. Or, if you prefer,
you can wrap the forms with waxed lunch paper held in place by a strip
of masking tape. To remove it, cut the paper with a razor blade and lift
off the form.
. . . preliminary operations
On a level surface place a piece of building paper or felt somewhat
larger than the form. On bare soil this will prevent the moisture from the
concrete's being lost in the soil, or the block's picking up grass and stray
bits of twigs and soil which may have to be removed if they are to be
mortared onto a concrete base later. If you are using a garage floor, a
walk, or a driveway for the casting, this will keep the blocks from
adhering to the floor surface. On these surfaces use at least 18 inches
extra paper all the way around the forms, so that the splashes, blobs or
screed scrapings will fall on the building paper and not on the cement
or concrete floor.
Either a trowel or a large-sized vegetable- or fruit-juice can may be
used to scoop up the mixed concrete from the wheelbarrow so that it
can be poured into the forms. Be sure to fill each corner well. Use a block
of wood to ram the concrete gently down into each corner and to joggle
the rest of it gently to release any air bubbles and pockets. Do this when
the form is half full and again when it is completely filled. When it is
half full, too, is the time to insert any reinforcements of wire, etc., you
may wish to use. Then fill the form to the top, pack it down well, and
add a bit extra so that it bulges a little on top.
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