Possibly

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Note added at 17 mins (2011-06-08 19:33:11 GMT)
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Lots of info (re slabs and general info) in this PDF which may be useful to you :

Slabs
Reinforcement is generally not required in concrete
slabs-on-ground used for single family residential construction.
Reinforcement, however, can help limit
cracking caused by drying shrinkage or large temperature
changes. When it is desirable to extend the distance
recommended between joints in outdoor slabs
(Section 7.1.3.2), welded wire fabric can be used to reduce
sizes of cracks and minimize infiltration of water,
deterioration of concrete, or other effects that could be
costly to repair. For such slabs and slabs in areas where
there are expansive or compressible soils that change in
volume in response to weather and affect the concrete,
reinforcement is used as discussed in Section 6.2.3.1.2.

surface of the slab is depressed more than 1½ in. (38
mm). Welded wire fabric should be placed in the middle
of the slab and should extend 24 in. (610 mm) from
edges of the depression, as shown in Fig. 6.2.3.1.1(a).
Openings in slabs should be kept to a minimum.
Large openings can cause non-uniform stresses that will
crack the concrete. Where 12-in. (300-mm) or larger
openings are required, the slab should be reinforced as
shown in Fig. 6.2.3.1.1(b).

http://www.bpesol.com/bachphuong/media/images/book/332r_84.p...


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Note added at 44 mins (2011-06-08 19:59:58 GMT)
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Another ref which may be useful:

http://www.concrete.net.au/publications/pdf/concretebasics.p...