For the heck of it I poured a mixture of some water & vinegar (as you had suggested) on the white powder and most of it dissolved, however, some of it just turned a light tan color and became a mushy consistency. Do you know why some of it turned tan and mushy?
I've seen efflorescence on brick and concrete in the form of a light dusting or a light to heavy film of efflorescence, but nothing like the HEAVY concentrations of the white powder on my basement floor...like I had said, some of it is built up 1/16" to 1/4" deep under some of the vinyl tiles. This is 45 years of build-up that the previous owners never took care of, plus, the tiles were trapping the powder between them and the concrete.
I didn't know that efflorescence can get so bad that there is so much of the powder that you could actually scoop it up with a spoon. Does this large concentration of salts normally happen if it is left to build up over a 45 year period?
I'm planning to take up the vinyl tiles in the near future, and it's going to be a mess with the black mastic all over the floor! I'll also have to find out how to resolve the moisture issue.
Do people typically install new floors (vinyl, ceramic) directly on top of concrete? Is it best to install a wood subfloor and then attach the vinyl or ceramic on top of the wood subfloor?
Sorry for all the questions. Thank you again for helping me with this issue! I appreciate your input.