patching a slab on grade

huangyhg

patching a slab on grade
a plumbing leak caused the contractor to cut out a 5'x5' section in the newly poured 4" slab on grade.  non pt.  just wwf. light loading.  they had to dig down and refill the subgrade after the patch.   
i just want to see if anyone has any recommendations for a repair product or procedure other than just drilling and epoxying rebar into the remaining concrete and patching the 5'x5' area w/ concrete.
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i think you are on the right track.  bout the only thing i know what to do.
if they left a bit of wwf around the perimeter of the hole, new wwf can be lapped with this... else, it's likely of no concern if the 'plug' is reinforced. also, the edge of the opening can have a slight taper from the top to the bottom.
just a matter of making sure that the granular fill is well consolidated and pouring the concrete 'plug'.
dik
this may be a bit much for your purposes:
you could also consider undermining the existing edge of slab and pouring concrete in the space when you pour your patch.  good sub-grade and a concrete mix that doesn't shrink and proper curing.