Figure 7-46.-Hand tamp (Jitterbug).
freshly placed concrete surface. Do not use cement or
water as an aid in finishing the surface.
Floating has three purposes: (1) to embed
aggregate particles just beneath the surface; (2) to
remove slight imperfections (high and low spots);
and, (3) to compact the concrete at the surface in
preparation for other finishing operations.
Hand tamping, or jitterbugging (figure 7-46), is
done after the concrete has been screeded. Hand
tamping is used to compact the concrete into a dense
mass and to force the larger particles of coarse
aggregate slightly below the surface. This enables
you to put the desired finish on the surface. The
tamping tool should be used only with a low-slump
concrete, and bring only just enough mortar to the
surface for proper finish. After using the jitterbug,
you can go directly to using the bull float.
If a smoother surface is required than the one
obtained by screeding, the surface should be worked
sparingly with a wood or aluminum magnesium float
(figure 7-47, view A) or with a finishing machine. In
view B, the wood float is shown in use. A
long-handled wood float is used for slab construction
(view C). The aluminum float, which is used the
same way as the wood float, gives the finished
concrete a much smoother surface. To avoid cracking
and dusting of the finished concrete, begin aluminum
floating when the water sheen disappears from the
Figure 7-47.-Wood floats and floating operations.