Fig. 9—Placing the Water on the Stone (or Gravel)
which is on Top of the Mixed Sand and Cement.
Mixing Natural Mixture of Bank Sand and Gravel
Spread out the mixture of sand and gravel as much as the board will readily permit, add enough water to wet the gravel and sand thoroughly, spread the cement evenly in a thin layer over the sand and gravel, and turn over, as described previously, at least three times, adding the rest of the water necessary to get the required consistency while the materials are being turned. It requires some experience to work up a natural mixture of bank sand and gravel, and if at all doubtful about the concrete made from it, first screen the sand from the gravel, and then mix in the regular way.
Fig. 10.—Mixing the Stone (or Gravel) with the Sand and Cement.
Number of Men
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.