MiamiCuse wrote:

Snipped

Robert:

Just one more question regarding using concrete mix under the overhanging
portions of the existing slab - since there are copper supply lines and PVC
drain lines tucked under the slab (the plumber deliberately excavated there
to route the pipes through...by packing concrete there wouldn't I be
embedding the drains and supply in concrete? Something about this makes me
uneasy. I can wrap the copper with sleeves (I plan to anyways) to avoid
contact with concrete, but seems there should be a way to provide support
without encasing the lines into hard concrete.

What is I take the big rocky chunks from the demolition of the original
slab, and wedge as many pieces as I can underneath, and pound them in with
rubber mallet? Will this work at all?

Thanks,

MC

No, don't do that. Sleave the copper and then fill with sand up
to the top of the pipes, so that they are just visible. Wet this
down to compact it and then add more sand if needed to almost
cover the pipes and repeat. As you wet it down, it should fill
all the voids in and around the pipes. After doing this, do the
slurry mix. (You should wet down the sand under all of the patch
just before you place your concrete anyway.)

If you think it is too tight, its not. Just make your slurry wet
enough to flow easily into all the gaps and crevices. As long as
you do this, your pipes may be touching the concrete, but it
won't be embedded in it. And even if it was, that is not a bad
thing in and of itself. It is bad if this causes your slab to be
less than 3 inches thick, because it would cause the concrete
over that pipe to crack along that pipe. Kind of like a control
joint in reverse.

Don't worry, be happy!

--
Robert Allison
Rimshot, Inc.
Georgetown, TX