Calcium chloride absorbs moisture from the air at a known, fixed rate. Each vinyl flooring manufacturer has a maximum acceptable level for this figure. The concrete alkaline test kit is similar to its a swimming pool test kit. The concrete surface should be clean and stripped of any coatings. If necessary, you can use adhesive removers or a rotary floor sander to clean the surface.
Concrete tends to be alkaline, but the surface has the lowest alkalinity due to aging.
Therefore the concrete surface should not be ground down more than a very small amount. The color of the strip determines the pH, which is compared to the vinyl floor manufacturer's specifications. If you have high levels of either moisture or pH, there are some actions you can take. So be sure to purchase a sealer that is compatible with the flooring adhesive. You can, of course, lower the pH the old fashioned, dangerous and sloppy way.