1st.—_Very Wet Mixture._—Concrete wet enough to be
mushy and run off the shovel when handling, used for
thin walls or for thin sections, etc.
2d.—_Medium Mixture._—Concrete just wet enough
to make it jelly-like, used for foundations, floors,
etc. To better describe this mixture it may be said
that a man should sink ankle deep if he were to step
on top of the pile.
3d.—_Dry Mixture._—Concrete like damp earth, used
for foundations, etc., where it is important to have
the concrete “set” up as quickly as possible.
The difference between the mixtures is, that the dryer the mixture the
quicker will the concrete “set up”—but in the long run, when carefully
mixed and “placed,” the results from any of the above mixtures will be
identical. It may be said, however, that a dry mixture is the harder to
handle, must be protected with greater care from the sun or from drying
too quickly; and lastly, is likely—unless used by most experienced
hands—to show voids or stone pockets in the face of the work when the
“Forms” are removed. The less the voids in the stone or gravel, the
greater will be the volume of the concrete. In general, the amount
of concrete will be greater in each instance than is shown in the
table—especially when gravel is used.
[Illustration: Fig. 2.—Concrete Mixing Plant, showing Concrete Board,
Tools, etc., Necessary for Mixing Concrete by Hand.]