The Hand Mixing Method
There are many ways of “hand mixing,” all having the same good results. The way described here we believe to be the one best calculated to obtain good results with a minimum of labor. In this description, and the accompanying illustrations, we have taken as a basis a “Two-Bag Batch” of 1: 2: 4 concrete.
First load your sand in wheelbarrows from the sand pile, wheel on to the “Board,” and fill the sand measuring box, which is placed about two feet from one of the 10-foot sides of the board, as shown by the diagram in [Fig. 3]. When the sand box is filled, lift it off and spread the sand over the board in a layer 3 or 4 inches thick, as shown in [Fig. 4]. Take the two bags of cement and place the contents as evenly as possible over the sand ([see Fig. 4]). With the two men at points marked “x” and “xx” on the sketch below [Fig. 4], start mixing the sand and cement, each man turning over the half on his side of the line AA. Starting at his feet and shoveling away from him, each man takes a full shovel load, turning the shovel over at the points marked 1 and 2 respectively in [Fig. 4]. In turning the shovel, do not simply dump the sand and cement at the points marked 1 and 2 in the diagram under the cut, but shake the materials off the end and sides of the shovel, so that the sand and cement are mixed as they fall. This is a great assistance in mixing these materials. In this way the material is shoveled from one side of the board to the other, as shown in Figs. 5 and 6. [Fig. 5] shows the first turning, and [Fig. 6] the second turning.
The sand and cement should now be well mixed and ready for the stone and water. After the last turning, spread the sand and cement out carefully, place the gravel or stone measuring box beside it as shown in [Fig. 7], and fill from the gravel pile. Lift off the box and shovel the gravel on top of the sand and cement, spreading it as evenly as possible. With some experience, equally good results can be obtained by placing the gravel measuring box on top of the carefully leveled sand and cement mixture, and filling it, thus placing the gravel on top without an extra shoveling. This method is shown in [Fig. 8]. Add about three-fourths the required amount of water, using a bucket and dashing the water over the gravel on top of the pile as evenly as possible. ([See Fig. 9]). Be careful not to let too much water get near the edges of the pile, as it will run off, taking some cement with it. This caution, however, does not apply to a properly constructed mixing board, as the cement and water cannot get away. Starting the same as with the sand and cement, turn the materials over in much the same way, except that instead of shaking the materials off the end of the shovel, the whole shovel load is dumped as at points 1 or 2 in the diagram under [Fig. 4] and dragged back toward the mixer with the square point of the shovel. This mixes the gravel with the sand and cement, the wet gravel picking up the sand and cement as it rolls over when dragged back by the shovel. ([See Fig. 10]). Add water to the dry spots as the mixing goes on until all the required water has been used. Turn the mass bade again, as was done with the sand and cement. With experienced laborers, the concrete should be well mixed after three such turnings; but if it shows streaky or dry spots, it must be turned again. After the final turning, shovel into a compact pile. The concrete is now ready for placing.
Fig. 5.—First Turning, Sand and Cement.
Fig. 6.—Second Turning, Sand and Cement.
Fig. 7.—Filling the Stone (or Gravel) Measuring Box—First Method.
Fig. 8.—Filling the Stone (or Gravel) Measuring Box When
on Top of Mixed Sand and Cement—Second Method.
Fig. 9—Placing the Water on the Stone (or Gravel)
which is on Top of the Mixed Sand and Cement.