On Oct 10, 9:32 pm, "MiamiCuse" wrote:
Hi I used a jack hammer to open the 4" concrete slab and made a trench for
the plumber to come to redo the underground pipe fittings.

Once they are done I need to pour the concrete slab back.

Question I have is...

(1) As I broke off the old concrete slab, there were a lot of the large
chunks of concrete I have as debris. Should I use those to fill in the
trench up to the 4" mark below grade, or should I use sand and pack them
tight?

As long as they're not pressing on the pipe, sure use them as fill.
Just make sure that whatever you put down is well compacted. Lift and
drop a sledgehammer over the entire trench fill then smooth out the
surface.

(2) There were wire mesh inside the concrete slab that I broke up. The
trench is about 8" to 12" wide about 10 feet long. Is there anything I need
to do as far as the wire mesh? Should I cut another wire mesh of that size
and put it in? The way many of them broke off I am not sure I can tie back
to the old ones.

It really doesn't do all of that much. If your slab wasn't cracked to
the point that the sides were uneven, it's not going to prevent
anything. The subgrade preparation was adequate and the mesh was used
as insurance. If it makes you feel better, put it in - it can't
hurt. Just won't help if you prepare the trench subgrade properly and
place the concrete correctly.

(3) Underneath the concrete slab is a sheet of plastic, is that a moisture
barrier or some insect barrier? Now that it's broken what can I do to have
the same effect?

Put some more plastic back. Again, it's not going to do much as
there's no real way of sealing poly to poly easily. It's cheap and
easy enough to do, but any little gap will allow moisture to migrate.

R