Chemicals to eat through concrete?

[lock]

Hey,

Just wondering what chemicals are capable of eating through concrete, specifically hardened concrete.

From what I know about concrete, it's formed by hydration, has a high compression strength and low tensile strength. Rebar is used to raise the tensile strength.

From this, I think you could have two possible attacks. One would be a rapid expansion contraction, which would take advantage of the weak tensile strength. This would probably be done easily with a hot/cold attack.

Alternatively, you could dissolve it with chemicals. Any ideas as to what would do the job??

[festergrump]

This (http://www.roguesci.org/theforum/showthread.php?t=1013) thread might have been of some use to you had you UTFSE, but you mustn't have, else you'd have posted your question there instead of starting a new topic...

Or try searching for "Dex-o-pan" posts from NBK2000 to crack the concrete in more or less of a controlled manner.

How about some more detail on what you're looking to do or not searching correctly or thoroughly enough for?

[ChippedHammer]

What about concentrated hydrofluoric acid?

Just make sure you bring some good gloves and a respirator with you.

[lock]

Lock> "Just wondering what chemicals are capable of eating through concrete, specifically hardened concrete."

Festergrump> "How about some more detail on what you're looking to do or not searching correctly or thoroughly enough for?"

Sorry, I was interested in what chemicals are used to eat through hardened concrete, not standard concrete. The hardened concrete used in bank vaults is of specific interest.

When I searched for "hardened concrete" I only found 7 matches, none of which I found helpful..

That other thread has some good info, thanks.

[teshilo]

Hardened? Hmm...I know what in component of liquid rocket fuel eat concrete Compounds as hydrazine and his derivates as tetrafluoride...And small tip :any high-reactive compound very toxic and his use in closed space very danger..

[Bugger]

To vary the subject slightly, what would be the best (and safest) chemical with which to corrode steel rebar, and also galvanized steel pipework which is used to form a barrier against personnel? The chemical could conveniently be introduced into and contained by the inside of the pipework, though a hole or an end of the piping, especially where it is vertical and stuck into the ground or a block of concrete. I would think that concentrated HCl would be best, because of FeCl2, FeCl3, ZnCl2, and the FeCl4- anion being very soluble in the water of solution left behind, being more soluble than the FeSO4, Fe2(SO4)3, and ZnSO4 which would be formed if H2SO4 were to be used.

Besides, concentrated HCl is less hazardous to handle than concentrated H2SO4; and can more readily be bought cheaply as an impure "technical" grade from hardware stores (or in some places supermarkets) as a soldering flux. In some places, concentrated H2SO4 can also be bought in hardware stores, because of its use to "pickle" (remove rust from) mild steel and cast iron prior to plating with Zn or painting with a rust-proofing primer.

Because the oxides of both Fe and Zn are amphoteric, a strong alkali, e.g. concentrated NaOH, which is sold in hardware stores and some supermarkets as drain cleaners like "Drano", may possibly also be used; but Na zincate or ferrite(II) or (III) are not as soluble as Zn and Fe chlorides.

[megalomania]

I am sure there are many chemicals or combinations of chemicals that could do the job, but I would think it would take months, if not years to "eat through" a substantial thickness. Even if you do have chemicals that can dissolve or loosen the concrete, you may require substantial volumes of them.

Trade books on concrete chemistry would be a good place to start. Also books on geology and geological experiments. Geologists sometimes chemically dissolve rock samples and may have a slew of appropriate formulas to use.

[Unsunghero]

Bugger it is extremely difficult to keep high concentrations of HCl liquid, as a matter of fact the boiling point of 38% is 48 degrees C..the highest chemically possible concentration of HCl is a little over 40% when it's not gaseous. Containing gaseous high-conc HCl, while I'm sure it's possible would take quiet a bit of effort and specialized equipment.

Acid-wise I would try H2SO4 because unlike nitric it doesn't nitrate your flesh if you screw up and it's not a pain in the ass to concentrate.

Once when I was doing a little "experimenting" in my garage I spilled ~97% H2SO4 on the concrete floor (standard home depot mix). I was a little bit busy doing something else to notice for about 3-4 minutes. Once this little spill was rinsed with sodium bicarb I noticed that the concrete the H2SO4 had come in contact with was almost a powdery substance (very very coarse) about half an inch down.

You could probably get some type of liquid dispersal unit you could use with the H2SO4 and a compressor or long piece of metal. Let the sulfuric sink in scrape/blow it, move on. If you don't care about noise you could possibly throw a pretty good amount, wait a couple min, slam it with a hammer.

Of course iron rebar reinforcements might be a *little* harder /sarcasm, I honestly haven't seen what sulfuric does to it, you might try nitric acid seeing as how it tends to corrode metals..containing and dispersing might be complicated though.

Just my 2 cents.

[nbk2000]

Chemicals take time...a LOT of time.

If you need stealth, that's about the only time I can think of chemicals being better than explosives for the job.

Regarding the rebar, you can cut that with tools very quickly and quietly.

If you need to cut rebar very quickly, and noise isn't a concern, than a rebar cutting attachment that goes on a rifle will do the job. Simply line up the rebar in the cutter and pull the trigger. The bullet cuts the rebar. :)

[Unsunghero]

Though it takes lots of time to completely destroy it, it seems like it would weaken it almost instantly. 2-3 minutes and I could dig the concrete out of the floor with my hands if I wanted to.

That rebar rifle attachment is possibly one of the coolest things I've ever heard of..I just can't see how it would work without ricochet etc.

[Nighthawkinlight]

A rebar cutting round is used (at least used to be used) quite often. I knew a man that worked with concrete his whole life. He and my father both worked long days doing nothing but blasting rebar.
My process would probably be to just find a time when dexpan would have time to work without anyone noticing.

[nbk2000]

The rebar cutter uses standard FMJ ammo, which just blows apart upon impact with the rebar, severing it in the process.

http://blog5.fc2.com/g/gaga/file/sherrif_troy_2.jpg

The attachment acts as a guide and shield, to contain the bullet fragments.

http://www.lewismachine.net/product.php?p=129&cid=11&session=bbff2da418ee87a2b154c82b8edf95f9