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.