Like any other material, concrete has a pH level which can range from acidic to alkaline. Freshly mixed concrete tends to be extremely alkaline, but the pH changes as it cures and comes in contact with new natural elements. Complications may occur if pH levels are too high, most notably difficulty with floor installations. A pH test can help you determine whether changes must be made to the concrete before a new floor installation occurs.
Sand a 12-inch section of the concrete floor with an electric sander and 200-grit sandpaper. A very thin layer of concrete, no more than 1/16-inch thick, should be removed from the concrete surface to get rid of any impurities that may affect the test results. You can manually sand the concrete if you do not have access to an electric sander.
Sweep up the concrete dust with a broom or vacuum cleaner.
Hold one end of a pH testing strip against the surface of the sanded concrete.
Drop one drop of distilled water -- which should be included in the test kit -- on the pH test strip. The test strip must be pressed against the concrete to get results.
Compare the color of the test strip to the pH color guide included in your test kit.