Concrete Mix Water Chemistry 1

[Backfill]

I have water sources which run moderately high in sulfate (30-220 ppm) and high in nitrate (50 ppm as N). I've been searching for references which may indicate whether these may present problems as concrete mix water. The ASTM STP 169C (Concrete and Concrete-Making Materials has no specific reference to nitrates. Since calcium nitrate functions as an accelerator and/or corrosion inhibitor, is it reasonable to expect that a high level of nitrates will not be deleterious to concrete in the mix water? Incidentally, I have no information on whether ammonia(um)which may be present.

Any advice would be appreciated. Have a safe shift.

 

[Ron]

Nitrates can present a setting problem. Sulphates present a long term deterioration problem. You can use either a Type II portland cement or Type V portland cement to help overcome the sulphate problem.

I would suggest a few trial batches with some reactivity testing and durability testing before you do a lot of concrete under these conditions.

 

[concreteguru]

In addition to Ron's advice, I would suggest that Type V Portland is in very short supply throughout the U.S. An alternative would be to use a Type II plus enough slag cement to give you the chemical composition of a Type V cement. Typically a mix design with Type II Cement and 50% slag cement will give you the sulfate resistance you are looking for in a Type V Portland. Check with you cement company technical rep or with the Portland Cement Association.

Good Luck with your project.


Fred J. Croen, RSM
Engius, LLC
Boston, MA
www: engius.com