Just got back from breakfast, my favorite spot, on a small Soi between Huay Kaew road and Nimmanhaemin road, CNX

Building a fair-sized building across the soi, form work and mesh/rebar being placed.

The Foreman of the job was going around measuring the height of the mesh for the slab, and ensuring that the rebar was centered in the form for the posts.

Made them do one post a total of 3 times while I was there watching. Some mesh needed to be raised to center of the slab.

Now about the quality of the concrete which they will use for this ...

Good workers are out there.

Depends on the volume of cement you are looking at.

If the Mods allow I would suggest you go with CPAC, unless it's local hand mixed (and nothing too wrong with that).

Best guide is to look at work they have done before.