Table 5.3—Reduction in strain due to reinforcing

360R-28 ACI COMMITTEE REPORT
concern in doweled joints, where the dowels may restrain the
movement of the slab. For this situation, square or rectangular
dowels cushioned on the vertical sides by a compressible
material are available in dowel basket assemblies and can
reduce this restraint (
Fig. 5.10
 and 
5.12
).
For slabs that contain steel fibers, the sawcut using the
conventional saw should be 1/3 of the slab depth. Typically,
experience has shown that, when timely cutting is done with an
early-entry saw, the depth can be the same as for unreinforced
(plain) concrete for lower fiber concentrations and preferably
1-1/2 ± 1/4 in. (38 ± 6 mm) for higher fiber concentrations up
to a 9 in. (230 mm) thick slab. Regardless of the process
chosen, sawcutting should be performed before concrete starts
to cool, as soon as the concrete surface is firm enough not to
permit dislodging or spalling of steel fibers close to the floor
surface to be torn or damaged by the blade, and before random
drying-shrinkage cracks can form in the concrete slab.
Shrinkage stresses start building up in the concrete as it sets
and cools. If sawing is unduly delayed, the concrete can crack
randomly before it is sawed. Additionally, delays can generate
cracks that run off from the saw blade toward the edge of the
slab at an obtuse or skewed angle to the sawcut.

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