Efflorescence (leached white, "frosty" crystalline salt bloom deposit) 2

[ContemporaryCurber]

I am looking for a concrete addmixture to eliminate efflorescence from appearing with out jeopardizing strength & durability in plastic concrete and morters. I have seen some products that claim to controll it but, do they totaly eliminate it from appearing? If anyone knows of such a product that really works please let me know your help is much apprciated thank you.

 

[mkashi]

The white stuff is calcium hydoxide and can be eliminated with a reduced permeability in concrete. You can use pozzolans such as silica fume or fly ash to reduce the permeability of concrete. A reduced water to cement ratio will help as well. Super plasticizers can help to acheive the workability you need with a reduced water to cement ratio concrete.

 

[ContemporaryCurber]

Thanks mkashi for the tip. Do you know of a particular product I could use that has these quality's that you spoke of?

 

[mkashi]

Well, I don't know if fly ash is available in your area. This is the least expensive alternative. You should use clean type F fly ash with a free Carbon content of less than 4%. Fly ash with Carbon content of more than 4% will work as long as you are not using plasticizers or air entraining agent. The free carbon in fly ash will prevent the action of these admixturs.

Good Luck
Mohsen

 

[hornet2]

Metakaolins are another pozzolan that can be used. Lime is the culprit as mkashi mentioned. Pozzolans react with the lime which takes it out of the equation. As a result of the pozzolan and lime react yielding a stronger mortar. Pozzolans are very fine particle sizes compared to cement and as a rule of thumb their use lowers permeability.

 

[ContemporaryCurber]

Thanks for the tip hornet2 your tip was well recieved.