Parge recipe Tools, Tips and Techniques Discuss Parge recipe in the Pizza Oven Design and Installation forums; In your case, the parging is to fill the voids in the concrete. Just about anything will do. I'd use ...

[Neil2]

In your case, the parging is to fill the voids in the concrete.

Just about anything will do. I'd use a 1:1 mix mortar sand to portland cement. Mix it up fairly sloppy and force as much of it into the voids as you can.

[Tscarborough]

One to one is not a good ratio for rubbing or parging. The purpose of the portland cement is to coat the aggregate, not provide body. At a 1:1 ratio, shrinkage cracking and dusting will happen and the mix will not achieve sufficient strength to resist freeze/thaw. You are making a slurry at 1:1 which is used as a bonding agent (while uncured) between layers of old and fresh properly mixed mortar, stucco, or concrete.

[david s]

The addition of lime in the mix gives it more elasticity when dry and also creates a stickier mix which helps application. Be careful lime is hard on your skin, wear rubber gloves. If applying a number of coats it is recommended to increase the lime content for each subsequent coat. I use a 4:1:1 sand, cement, lime mix with two kinds of fibers added for strength.

[kebwi]

Thanks everyone. I'll weigh my options carefully.

[Neil2]

"One to one is not a good ratio for rubbing or parging. ."

I agree, but in kebwi's case, he wants to fill voids left from the original concrete pour. Here is a photo of his slab.

[Tscarborough]

It doesn't matter. At a 1:1 ratio, there is not enough aggregate. The paste will remain soft and chalky and act as a bond breaker for any subsequent application of material.