Acid etching with Muriatic acid

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Texas Concrete Design's picture
Texas Concrete ...

Earlier this week we started an epoxy flooring project (half existing concrete half new concrete). Just as we always do, working in 10x 10 ares, we mixed a 1:20 acid/ water solution, applied acid solution, scrubbed with a black pad, neutralized with ammonia (1:3 solution), scrubbed, and vacuumed (mechanical profiling was not an option because of being a laboratory environment). We completed the existing slab with no issues. Upon starting on the new slab, when we vacuumed, the slab began delaminating. We thought that it was only one area so we continued. The slab continued delaminating so we stopped and contacted the owner (working directly for owner and not GC). The entire slab is delaminated.

The next day we had a meeting with the Engineer, GC, owner's rep, concrete guy, and concrete supplier. They all preceded to say that the acid caused the delamination. At first I thought they were joking, but they were very much serious and asked how I was going to fix it (my expense).

After doing extensive research, I can not find another instance of this happening or a manufacturer warning of this possibility.

Does anyone have any experience with this happening or ever heard of muriatic acid causing delamination?

dcs inc
Just for clarification. Was

Just for clarification. Was that 20 parts acid, 1 part water or the other way around.

I always show it as the base material that you are diluting as the 2'nd number.

Never heard of this happening.... (Now I'm assuming the 20 parts was water)

At that dilution, you are not going to destroy a concrete surface causing delamination. Something smells a bit fishy here. You can find information to support your side of this, don't let them snow ball you. gene

Texas Concrete Design's picture
Texas Concrete ...
1 part acid 20 parts water

1 part acid 20 parts water (5% solution). I hate messing with the stuff so I keep as diluted as possible.

we use 1:8 of home depot's

we use 1:8 of home depot's stuff & a proportion of that ratio to lowe's,,, imagine your original acid dilution determin'd the 1:20 ratio.

what was the depth of delamination ??? is anything left of the original surface ???

best [the original] suspecting-crusting-or-crazing yic-yac

jeff is right, that's the

jeff is right, that's the other concrete problem it could be - finishing. they may have started troweling before all the bleed water came to the surface and evaporated.

poor curing, too much mix water, or premature finishing. those are your most likely culprits.

Texas Concrete Design's picture
Texas Concrete ...
1/16"-1/8". It is amazing

1/16"-1/8". It is amazing that someone would would think that in a matter of 5 minutes you could have a acid penetrate 1/16"- 1/8" and uniformly delaminate an entire 1000sf.

delamination of the surface

delamination of the surface of the concrete does not happen with muratic acid. Especially at a 20:1 dilution. Thats not much more powerfull than soda water if at all.

Delamination almost 100 percent of the time is due to the concrete mix and/or how the concrete was finished.

These guys are trying to make you responsible for their problem.
You may be able to find some info from ACI
Check out
There has to be some kind of info from them about this so you can have some proof of where delamination comes from.

For them to say its your fault from cleaning is rediculous

no, the other guys are right,

no, the other guys are right, concrete will not delaminate from acid etching. it's practically impossible. especially at a 20:1 ratio . normal acid etching is done at about 8:1.

EPOXY can and will delaminate from concrete after acid etching if the surface is not thoroughly rinsed of the residue or the residue dries before it is rinsed. this happens through osmotic blistering. the remaining salts attract moisture from below the concrete surface and pressure builds up on the underside of the coating often leading to delamination.

but never the concrete itself. usually that is from poor or no curing, where the surface of the concrete dries out before it fully hydrates, or from too much mix water, making the surface extremely weak. these guys are crazy if they think acid etching is what caused it. no true construction professional, be it architect, engineer, or gc, would come up with something like this. the concrete guy(s) is obviously just trying to deflect blame from himself.

if they insist you are the problem, then tell them to have a testing company come out and do some core tests of the concrete. or some adhesion pull testing. i bet you anything the concrete tensile strength readings would come up low. you can get the pull testers from elcometer. wouldn't be a bad investment right now for you, they're not that much money.

the other thing you could do is use a pressure washer. on good concrete, you should be able to use up to 4,000 psi without damaging the concrete. if stuff starts coming up at or below that, then you know the concrete is the problem.

Yeah.. that kind of dilution

Yeah.. that kind of dilution is not going to damage a normal concrete slab.. at all... is it delaminating anywhere else or just where you acid etched... walk around with a screw driver and scrape the surface you haven't treated.. see if you dig in... sounds like a concrete finishing problem to me...

can imagine everyone pointing

can imagine everyone pointing their fingers EXCEPT the engineer,,, you'll need some core samples &, probably, petrographic analysis,,, but FIRST, you'll need a good attorney who specializes in const claims & specs,,, this is going to get messy so it might as well be you who throws the 1st rock,,, you outta know their rocks're headed your way already.

another partner in this action should be your insurance carrier so give your agent a ' head's-up ',,, they'll also have technical resources avail,,, sometimes its nec to write 'em a letter stating they aren't to settle,,, however, if you're sued & lose, its out of your hands,,, bear in mind your ins co doesn't care - its just biz & #'s,,, this isn't the 1st time this has happened & you're not unique - just unfortunately in the wrong job at the wrong time.

this is why our contracts have the ' hold harmless ' clause,,, we're, as a trade, considered conc enhancement specialists/experts/artisans w/no control over other work much as the roofer has no control over the framers yet must rely the former's work was acceptable as the latter places his life/limb at risk subsequently,,, e me if you'd like a copy.

pressure washer psi works w/fan nozzles held back from the surface,,, use a 0 nozzle on 3,500psi conc from 6" & the resultant tracks'll be described as damage 'cause fines start popping out,,, btw, you never mention what psi was used, type of project, placing conditions, admixtures, etc.

best [the original] not-1st-time-at-this-rodeo yic-yac

Texas Concrete Design's picture
Texas Concrete ...
Thanks suntacsys, but with

Thanks suntacsys, but with this being a project for Texas A&M, they do not sign my contract. With my degree being in Construction Science, from A&M, my first is going to be visiting with some of my old professors.

I still can not believe that I have to spend money defending myself on something that is so obviously out of my control nor my fault.

const science shouldda

const science shouldda included some courses on const law, contracts, liability, time/method of notice, undiscovered site conditions, req paperwork, etc - all the stuff that makes it so much fun ;-) that's the main reason bid packages incl many pages on contract rqmts regarding legal stuff/matters & usually fewer on specifications,,, doing the actual work's nuttin' - guys do it everyday w/o knowing how to read/write/speak english.

its all part of the const arena,,, IF your prof's have the initials ' P E ' after their name, you might get lucky IF they don't hide behind conflict of interest,,, i'd certainly expect their loyalty's being directed to the name on the btm of their paycheck,,, most pe's can't/won't take the paycut to work for institutions as there's no bonus $$$ or profit sharing,,, 'fraid you're liable to find out the best & brightest aren't teaching,,, welcome to the real world which's never been confused w/ivy-wall'd academia.

your expectation of existing work ( the floor ) being sound & installed according to accepted const standards will be your 1st line of defense,,, notifying the owner of anything less is also a concurrent obligation,,, not going to expand on more publicly but if you want, send me an e,,, hopefully, you've got all your proprietary paperwork in order - if not, GET 'ER DONE immediately,,, the written piece of paper is MUCH stronger than anything else when it comes to claims.

' something that is so obviously out of my control nor my fault ' may be your view but it'll be up to an arbitrator or judge to determine if your view's the prevailing decision,,, hopefully, there's a clause somewhere in the paperwork entitled ' termination for convenience '.

btw, this is not about the quality of work,,, its ALL about who's got the best paper trail,,, if a party can transfer liability to another party, guess who pays ??? your contract's probably NOT w/A&M but either w/GC, 2nd tier, or 3rd tier,,, hopefully its w/GC as ' rights ' & obligations vary w/other tiers,,, while you probably have the same obligations as the prime to the owner, your rights will be markedly different,,, better brush up on tx lien law while you're at it - in for a penny, in for a pound ! ! !

best [the original] i-swear-to-tell-the-truth yic-yac

if you want to talk to

if you want to talk to professors, i would try middle tennessee state. they have a special concrete program for students.

the ascc also has some knowledgeable and helpful members and good resources.

ims polished co...
You should be able to get out

You should be able to get out of this without a big fight Texas. The worst possible thing to happen is the slab has a preexisting problem only to be reveled by your process. In other words the bolts were already out of the door but you happen to open it and the door fell off, therefore its your fault in there eyes. I have a feeling there is a preexisting moisture issue. Acids may cause little surface integrity (it is an acid lets remember it depletes) but not enough to make or break it. Hey another thought Texas was there a topical on this concrete before hand? Any signs of hydrostatic pressure?

Texas Concrete Design's picture
Texas Concrete ...
I use to work for several

I use to work for several large GC firms as a PM/ Supt. I had always been the one "bullying" the subs, but this is my first experience as being "bullied".

I have not officially, in writing, refuted the claim. I am one to have all my ducks in a row and play out all possible scenarios prior to proceeding. I have talked to acid manufacturers and engineers from throughout the country and I get the same response that it is not even chemically possible.

Thanks for all of your responses.

I would say you have to get

I would say you have to get the specs on the mix design and all the other data. I'd vote troweling before bleed water evaporated off. Especially if this was inside and they had a deadline. Could be air entrainment also, but not likely. Sounds like the acid was the final straw on a week slab. Ask them why wouldn't the old slab delam also, then? They f'd up, obviously, you just have to prove it.

Steve V
I agree on the finishing

I agree on the finishing issue. I'd bet that the slab was watered to aid in trowelling, creating a high water:cement ratio on the surface. Texas is hot, I bet it happens a lot there. Only trouble is proving it. Or maybe it rained when they were finishing and someone got the idea to sprinkle powdered portland cement on it and trowel it in to get a slick surface. Perhaps you could talk to someone on the finishing crew to find out what went on.
Someone else mentioned air entrainment. I've seen this as well. An architect spec's air-entrained for whatever reason and the hard trowelling causes delamination. Whatever happened, the acid is probably not to blame. Good luck on your dilemna.

Steve V

Texas Concrete Design's picture
Texas Concrete ...
I have already obtained the

I have already obtained the concrete test reports and the mud was good. It did not rain on that day. They could of jitterbugged it too much, got on it too early, etc. I have spent hours researching delamination and there are many different causes, but have yet to find muriatic acid as one of them.

can't imagine why anyone'd

can't imagine why anyone'd spec air on a tx slab,,, up nawth, sure, but tx has heat so i'm guessin' the finishers ' bless'd ' it too much & it was plac'd by hand rather'n powerscreed,,, thinking petrographic analysis'll be the only test.

best [the original] these-ain't-fun yic-yac

SweetCreteFloors's picture
we just pored a slab it was

we just pored a slab it was 100 degrees when it was pored and several places were real dark and I reached down to look at it and when I scrached the surface the whole top flaked off all the way to the gravels it has to be the finishers fault...


doesn't anyone use ice wtr in

doesn't anyone use ice wtr in transit mix conc ? ? ?,,, finishers don't usually order up conc nor spec it.

best [the original] not-nec-finisher's-fault yic-yac

Texas Concrete Design's picture
Texas Concrete ...
FYI, the owner notified me

FYI, the owner notified me that they are going to pay me for the work I completed to date, terminate my PO, and are going to re-bid the project (to include repair of the delaminated floor).

congrats, chris,,, sounds as

congrats, chris,,, sounds as if someone else did their homework & needs to get out of a jam,,, there are some other things you could invoice but probably best to get outta dodge,,, be interesting to find out who gets backcharged for the repair work.

curious what the prof's said when you talk'd w/'em ???

best [the original] pack-up-the-truck-boys yic-yac

sounds like they realized

sounds like they realized their mistake but won't acknowledge it. otherwise, they'd keep you on the job. they must know they poisoned the relationship and would rather not deal with you than say they're sorry.

this is probably the best case scenario for you, though. you don't want to work for people like that. this is an easy out for you AND you're getting paid. that is cool. couldn't have asked for anything better imo.

I love happy endings!

I love happy endings!

Lindy A.'s picture
Lindy A.
Wow, congradulations ... you

Wow, congradulations ... you must have a pocket full of 4-leaf lucky clovers. What a great outcome :>) They obviously knew they were only standing on only 1 leg, and that if they didn't pay you for the work you had done that you had the ability (industry support and knowledge) to make your case and kick that 1 leg out from under them (leaving you as the best man standing).

Unfortunately your successful outcome (without attorneys and a mudslinging match) is rare ... typically the last person/contractor on the job (substrate) becomes the fall guy (you stood up for yourself, didn't waiver, and won).

Lindy A.

Just a FYI on Muratic. It's

Just a FYI on Muratic. It's Hydrochloric acid cut with water.

Anyway, i worked in a plant where we used thousands of gallons of it. It had a pit around the tank. It NEVER delamed the concrete. EVER. And, that's un cut.

Now, Sulphuric that we had in the other tank and used thousands a day. It's pit was all ate up.

Congrats!! They must have

Congrats!! They must have known or realized there was a problem there!! But I have to say.. normally if the owner digs in for a fight.. it will be a steel cage death match... I"m glad it didn't come to that for you!!! Hollar!