Sodium Acetate

Sodium acetate is deliquescent. The reaction will occur (vinegar on baking soda "volcano") but water will not be driven by evaporation.

Also, sodium acitate isn't very expensive. 10lbs of anhydrous for $40 shipping included.

https://www.ebay.com/itm/Sodium-Acetate-Anhydrous-99-5-PURE-10lb-FREE-USPS-PRIORITY-makes-hot-ice-/232986891514?nav=SEARCH

The recipe for making sodium acetate is to boil down the vinegar/baking soda to remove the moisture.I have a concrete deck that gets VERY Hot (over 110F) in the summer,and water will dry almost instantly on it.My idea was to let the heat from the deck evaporate the moisture form the mixture instead of boiling it,thereby creating the sodium acetate in-situ on the concrete.

I intend to spray the baking soda solution on first, let it dry,then the vinegar afterwards until no reaction occurs.

I am not intending to make a super-saturated mixture as in the recipe,like is used in heat/cool packs, but rather to protect the concrete.

I expect the lime in the concrete will react with the vinegar as well,so what kind of an admixture will I have as a result?

My question really is,"Is heat necessary for the reaction to occur?" and "Should it be mixed before applying to the concrete?"

Will this work?Any chemists on the forum?

Thanks for any and all help on this.

Heat is not necessary for the reaction.

I would definitely complete the reaction prior to applying. Vinegar on concrete is going to react. Acetic acid reacts with calcium hydroxide yielding calcium acetate. This is unlikely to have any of the sealing benefits of sodium acetate and I would guess it is detririmental to th structural integrity of concrete.

My response is that your proposal is NOT equivalent to separate mix and dehydrate as there is no reaction end point that you can control.

The vinegar will react with the baking soda, but will then react with the concrete itself until that is neutralised. The neutralised concrete at pH 7 (or even 7.8) will not protect the rebar and corrosion of that will then cause spalling and delamination and premature failure of the concrete.

Your surface treatment will have different concentrations across the surface.

If you are going to try it at all, follow the recipe. If you are going to experiment, then conduct using samples you are prepared to loose through destructive testing to verify the results.

Thanks for the feedback everyone.

I will reconsider my options.

A quick search turned up the original study on which the "beneficial effect" of sodium acetate on concrete is reported.

https://pubs.acs.org/doi/pdf/10.1021/ie070527l

Take a look at the six cylinders which were put through freeze-thaw cycle to test the effect of different concentrations. It appears that 10% was too weak to protect, but 30% and higher had some corrosive effect detrimental to the concrete. So on this basis alone I would be very wary of reacting the soda and vinegar in situ upon your hot property.

However, the real take-away from this study is that the sample size is completely inadequate to base any firm conclusion as to the benefits or harms to the concrete. One small cylinder for each sodium acetate concentration and one control... composition of the concrete also not varied to assess. To say these results are preliminary is an understatement. I don't need to be an expert in chemistry to tell you that with complete certainty.

If I were you, I would do a thorough search for any further studies that validated - or clarified - the results reported in this one. You could start with the ones listed here:

https://www.researchgate.net/publication/279027283_Crystallization_Technology_for_Reducing_Water_Permeability_into_Concrete

If there is no better evidence of the safety and/or appropriate concentration and method of application, then it's up to you, whether you really want to just wing it and potentially destroy the decks you were hoping to protect. If you decide to experiment, please make a video for us, because there's always time for a good laugh.

You seemed to be happy with this solution (no pun intended) last time you asked.

DUH! You are correct.I forgot about that.

Must be getting that "oldtimer's disease."

That was one of those "When I get around to it" type projects.

Finally getting around to it.

Previous post gives everything I need to make it,but still picked up some valuable cautionary info here.

I will do further research before proceeding.

Thanks to everyone for their valuable time and expert advice.

If you are trying to waterproof the concrete, may I suggest you look into sodium or potassium silicates instead?

Potassium silicates is the best choice in this situation.