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I see many tutorials regarding stucco and concrete talking about bonding agent that is applied like a primer, but there is no such thing in Brazil (I guess).

What we do have is something describe as "synthetic resin, high performance cement additive", composed of "vinyl copolymer" that is milky white and smells like PVA glue. The instructions tells me to mix 2 parts water 1 part additive and use this solution as the water for the cement/sand mix to make a slurry to use between concrete and mortar on top. Or to make "chapisco" (it is cement and coarse sand very runny that is rolled or thrown on a surface to work like a scratch coat). But nowhere it says to use it as primer like the bonding agent.

Now I'm not sure if they are the same product and Brazil just uses for "chapisco" because this is the only thing that every brickworker does here or if they are completely different products.

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I believe it is the same product and can be used in either job as a primer or as an additive to give the concrete more resiliency and plasticity. Your description makes it sound like the same product here in N.A. To be sure it can function as a primer try this test: using a paint brush apply it full strength to a clean out of sight concrete surface. If after several minutes it dries to a clear to opaque finish it's most likely a concrete primer (the brush that was used should now have a plastic film from the dried polymer). To use as one I recall that the newly applied primer should not be allowed to dry before the cement is placed. If it does I think you just recoat with another application. To use it as an admixture for better workability (in mortar mostly): pour the recommended amount into a clean bucket and than add the required amount of water for the batch to the same bucket and mix. Now add polymered water to the batch.

  • So this type of "primmer" should be used wet, right? Weldcrete and some others that I see in YouTube videos are painted on, left to dry and then new cement is applied. – Luiz Borges Oct 30 '15 at 2:15
  • If the videos' are using the product from your question and are following the products instructions than you should.... (well, you already know the answer). – ojait Oct 30 '15 at 2:58

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