I was called to give a quote on this building. Apparently this new owner took over, and the previous owner had ammonium sulfate sitting against this wall, it got wet, and caused the indicated damage.
Client wants the wall pressure washed to get any remaining ammonium sulfate off.
The client understands that it will need pressure applied, but he doesn’t want too much pressure applied that it chips away any further at the wall (understandably).
I’ve never encountered a situation like this - I’m reaching out to you for any tips, methods, or ideas for the project.
In my OPINION, and it’s really just an educated guess. When the water hit the ammonium sulfate it released the ammonia that was bound and reverted to sulfuric acid. So your best bet is a baking soda rinse. Before I do all that though I would see if the acid is still active on the wall.
You can pick up pH paper at a few places, or you can order it online. Take normal water and dampen the scared area, then apply the pH paper. If it goes towards the acid side then use the baking soda and water rinse until the pH is normal in every area you test. If it’s neutral, which is what I think it will be, then there is no point. The acid was already neutralized by the alkaline concrete.
As for the customer saying he doesn’t want anymore chipped off…well, that’s not going to do him any favors. He needs to buff the concrete back to a smooth surface, or they will continue to have it cracking a peeling and there is a possibility that there is still active acid under some of the chips. This is basically a burn. How deep it goes is the question. It’s very similar to a human skin burn. Fine at first, but the damaged layers will start to flake and peel off. Getting down to the undamaged surface is the only way to stop this process of cracking and peeling over time.
This is my preferred pH paper, but any litmus test paper will work, it’s just pH paper is more accurate for those smaller pH shifts.
Do you all also think it would be a good idea to brush the wall dry and sweep really good before any water was added? You saw what happened last time the ammonium sulfate got wet and from the pictures it looks like there is still piles of the stuff
@CaCO3Girl First and foremost, truly appreciate your experience and knowledge. I took your suggestion, and as you guessed, the A. S. was neutralized (apparently it had been sitting there for years).
The pressure washer did a nice job of taking off the excess A. S. and left the concrete to where the client wanted and requested. How he chooses to move forward is beyond me. It was really an easy job, about 1.5 hrs total. Before my arrival, the client had his team scrape off the heavy chunks of A. S., which really made things breezy for me.
Again, thanks for the knowledge and recommendation. It helped me go into the job with a clear mind.
Glad it worked out. I used the pH paper trick when we had an overflow accident. Had to make sure everything was neutralized on the ground. It’s the easiest way to check pH
