Magnasium Oxide based Material Efflorensent problem

[shammypenny2]

My company is making products from Magnasium based cement for out door ornament, but there is a efflorensent problem when we placed out out door after heavy rain. We tried apply water proof sealer for conrete on our products but it still doesn't do much good. it could be because the sealer are made for calcium based material which is why it doesn't work on our product. Anyone have a solution to our efflorensent problem? Any water proof sealer out there are particularly for Mabnasium Oxide based product?
thank you

 

[oldestguy]

I see that there is no forum under the subject heading "masonry".

However, the engineers that practice in geotechnical subjects also generally are associated with construction materials testing. One of the common construction problems is efflorescence on concrete block and brick walls, etc. It is quite likely that you will get some help there.

I suggest re-posting in the forum "Geotechnical Engineering other topics"

 

[Ron]

Shammypenny2...I'm surprised that you are using a periclase base for a cementitious product. Have you had issues with expansion? Generally magnesium oxide, in the presence of moisture, will convert to magnesium hydroxide with a resulting high expansion...enough to damage concrete. Are you sure it is clearly a magnesium oxide or is it perhaps a gypsum based material?

As for the efflorescence, I am not surprised, since you have an unstable compound that will easily convert to carbonate and hydroxide forms. As for a solution to the issue, you might try a sodium or potassium silicate sealer, or if you don't want a reactive sealer such as the silicates, you can use a methacrylate penetrating sealer.

 

[shammypenny2]

Dear Ron,

Thank you every much for your answer.
As for your question, We never had any problem with expansion, as our products have done ASTM tests for thermal, and moist resistance.
Effloresce is really the only problem left for us.
thank you.