You should be aware that the vast majority of the construction companies, and in fact any major company, is owned by Thai Chinese or Chinese from the mainland. Would be difficult to avoid them.
Chinese are infamous to use sub-standard materials to maximize their profits.
Recent examples, the baby formula containing only chemicals with no nutrition whatsoever (many babies died), melamine laced milk, etc. There are hundreds of examples, too many to mention.
The same goes for construction, lowest quality steel rebars, lowest quality concrete.... you name it...
Just lucky China is not on a major fault line.
I just wonder how many skyscrapers in BKK have cracks, that get silenced with fat brown envelopes.