Disclaimer: No, I can't buy ready made surface leveler, because in Brazil this doesn't exist.
I need to use a resurface a dry pack levelling that my previous contractor made a lousy job (porous surface here and there and a few cracks, but it seem well adhered). He is not answering my calls and I'm not calling anyone else to fix something this small.
Everytime I mixed sand and cement I always got a headache on getting the right mix or the right type of sand (in Brazil there are at least 4 different types of sand: coarse, medium, fine, and washed, most from river beds).
What would be a good recipe for a resurfacer, also, I should use bonding agent, right?