Reinforcement protection when repairing concrete or plaster

[FGLIN]

I have learned that if you are going to make repairs where rusty reinforcement has been exposed, the reinforcement should be wire brushed and then coated with mönja. Now, only professional painters are allowed to purchase mönja and perhaps only for building conservation measures. The previous substitute, zinc chromate, which had a similar protective mechanism, is also probably banned, I believe. Does anyone know of any other suitable paint or protective procedure? The paint needs to function in the highly alkaline lime environment.

 

[Staffans2000]

Brush on Sika on the reinforcement and mix it in the mortar. A tip I got from an old retired mason.

Staffans

 

[Lerstenstegel]

Anyone can buy "mönja"?

Here is a good product from Caparol for rust protection. https://www.caparolfarg.se/produkter/utomhusfarger/metall/industriprimer-1233

But if you are going to fix it up anyway, as mentioned above, some Sika products already have rust protection, e.g. Quick 506. But it doesn't hurt to brush it before anyway, probably with loose Sika or with the paint.

 

[FGLIN]

Anyone can buy mönja?

Here is a good product from Caparol for rust protection. [link]

But if you are going to repair it anyway, as mentioned above, some Sika products already include rust protection, like Quick 506. However, it doesn't hurt to brush it before anyway, probably with loose Sika or with the paint.

There is probably a paint they call mönja and is red-yellow that is sold to the general public but does not contain the genuine mönja pigment (a lead oxide believed to provide very good rust protection even on parts that are already rusty). I will check out Quick 506, as there are so many Sika products that if you only have the name Sika, it can be hard to find.

 

[FGLIN]

Checked the safety data sheet, the corrosion-inhibiting additive seems to be 0.25-1% (more precise than that they probably don't need to specify) sodium nitrite. I'm surprised it's not potassium nitrite; I seem to recall reading that silicate paint should be made with potassium waterglass because sodium salts are allegedly not good for concrete, but on the other hand, antifreeze for mixing during winter casting is usually a sodium nitrate solution. It might be good in combination with some rust protection paint.

 

[Lerstenstegel]

Keep in mind that 506 Quick is indeed quick. Never mix a full bucket as you won't have time to use it all before it sets, but otherwise, it is a very good product with good build height and an easy-to-sand surface.