Acid Exposed Concrete

[AAEC]

Have this concrete that is already exposed to acid. You can tell that matrix holding the aggregates is partially gone and you can see the aggregate. I don't want to demo this concrete and I wanted to save it and overlay it with good sound concrete that is resistant to acid and base with PH level from 0 to 14. Is there anyway that I can neutralize the acid that was already in the concrete? We are planning to wash the concrete with caustic (soda ash before we place the new concrete. Is this enough?

 

[Ron]

Acid reactions on concrete are generally consumptive reactions, meaning when the fizzing stops, the damage is done. There is generally not a latent issue, except that the pH of the remaining surface has been lowered and if not covered, will allow a greater permeability of the concrete.

I would removed the upper 1/4 ot 1/2 inch of remaining concrete surface using a scabbling device or a grit blasting device (Blastrac or similar). Once this is done, you can then place a topping on the floor.

If you want to neutralize with caustic soda you may do so, but do that before you removed the additional surfacing.

 

[dik]

and susceptability to corrosion... love that line, "when the fizzing stops, the damage is done."

Just need an opportunity to use it (with attribution, of course).


Dik

 

[Zambo]

dik's point is important. I recommend cores and the use of phenolphthalein to check the depth of the carbonation. Is the full depth of concrete cover to any rebar affected?

If rebar is present it should be encased in concrete that will protect it from corrosion. I would neutralise the prepared surface as you plan.

 

[AAEC]

Thanks for the input especially to Ron.