"Robert Allison" wrote in message
news:ZOsuj.610$kI4.291@trnddc05...
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

Thanks Robert. I will try it.