For the above operation only two men are required, although more can
be used to advantage. If three men are available, let two of them mix
as described above and the third man supply the water, help mix the
concrete by raking over the dry or unmixed spots as the two mixers turn
the concrete, help load the wheelbarrows with sand and stone or gravel,
etc. Fig. 5 shows a third man on the board. In this illustration, he is
helping mix the sand and cement by raking it—a most effective practice.
If four men are available, it is best to increase the size of the batch
mixed to a four-bag batch, doubling the quantities of all materials
used. The cement board should also be increased to 10 by 12 feet as
shown under “Tools.” In this case start the mixing in the middle of the
board, and each pair of men mixing exactly as if for a two-bag batch,
except that the concrete is shoveled into one big mass each time it
is turned back on to the center of the board. When more than four men
are available, the rest may place the concrete, make new runs, load
wheelbarrows, etc., taking the concrete away from the board as fast as
it is mixed. In this case another small concrete board should be placed
next to the big “board,” so that in the last turning the batch can be
shoveled over on to the small board for placing, making room on the big
board to mix the next batch. The small platform need be only just big
enough to hold the pile of mixed concrete.