I am in the concrete leveling business where I install 1/4" to 3/4" of
self leveling polymerred cement on top of concrete to smooth and level
it.  I have recently done a large job where this Polymerred cement
when being installed leaked into the drain and hardened to a
consistency of approximately 5,000 psi.  The drain has a cast iron pea
trap that the material has leaked into.  My question is I need a way
to dissove the cement chemically without damaging the cast iron pipe. 
I am willing to pay $200 plus a $100 tip for and answer that works and
nothing if it does not.  I have tried muriatic acid with an auger but
we did not get
very far.

---

Clarification of Question by srockrae-ga on 13 Jul 2005 14:12 PDT

Answer to rplacing for $300 is no.  More like $10,000 as there are 4
drains in a highly finish building with P traps embedded in a 12"
concrete slab.

Hello srockrae,

I was unable to find much searching for an answer for this question.
The following might be helpful for you, however.



Question: 
Help! I desperatly need to know how to dissolve concrete from inside a
1" PVC conduit. Can you help me PLEASE?

Answer: 
Depending on where you are, battery acid is probably the most readily
available thing. The problem is getting it to the concrete in the
pipe. Once it is through cooking, he would need to rinse out the sand
and gravel that remained and do it again until he got through the
concrete. The problem with that method is AAA, always add acid first.
Straight hydrochloric acid would be the best thing. The stronger the
acid, the faster it will work, but the more difficult it will be to
work with safely. Also, a long piece of heavy rebar would be handy in
between soaks to bust up the semi-disolved concrete. As far as I know,
most PVC is impervious to acids. Concrete is only a small percentage
cement so it will be a slow process unless the concrete was made with
limestone. Hope this helps.

http://www.gamineral.org/FAQ.htm

I could not find how much of a problem this would be on cast iron. It
will etch it, but likely will not dissolve through, but I can not be
sure of this.

Good luck with this problem.

-=clouseau=-

Tough spot to be in. I have had problems similiar to this and have not
found a good chemical solution. Muriatic acid is pretty strong stuff
and if it doesn't work you may need a mechanical solution. Just be
sure you do NOT try a strong base  becuase there may still be some
acid in the pipe and you don't want the 2 mixing.

I am not a GA researcher.

You may be able to use hydrofluoric acid to disolve the silica in the
cement.  Another posibility is to use a salt solution.  The one thing
I will say is DO NOT get any of the hydrofluoric acid on you, IT WILL
KILL YOU!!!!!!!!!!  I strongly recommend before using it you read up
on it.

For $300 (your answer offer) couldn't you just replace the P-Trap.

I most probably will be able to solve your problem (as a Chemist), but
I will need a small sample of the solidified mix.

(not a GA researcher)

If the polymerized cement is of an organic origin, you might make some
progress with any number of organic solvents.  Furthermore, if the
cement is an organic polymer, it will likely have a signficantly lower
melting point than the cast iron of the pipe.  If this is the case,
and if there is a way to heat the pipe significantly so as to melt the
internally hardened cement, then you might get the material liquified
in order to make it flow through the pipe or at least spread itself
out possibly creating a small conduit for solvents to act more
effectively.