Concrete is made up of various elements of different hardness and densities that vary from region to region. Knowing the hardness of concrete will help you figure out what bond to use for your job.

The two most common tests are:

1. Rebound Hammer Test

2. Mohs Scratch Test

The rebound hammer method, also commonly referred to the Schmidt Hammer is a test to check the impact strength of a concrete substrate. This hammer has a piston that is engaged easily by the user, then when pushed on to the concrete. The scale on the hammer then produces a reading in PSI (pounds per square inch) of the tested area. Low readings could signify faulty strength concrete or hollow spots. These need to be addressed prior to doing any surface prep.

The Mohs scratch test is more common today, especially with the large amount of concrete polishing that is being done. A standard test kit contains 9 different tipped “pencil” looking picks. These are typically numbered #2 through #9. Diamonds are rated 10 on the Moh scale and are the hardest mineral known to man. Conversely talc being soft  has a Moh rating of 1.

The test is performed by starting at a low pick, such as #3 and making a two inch line coming toward you with downward pressure. The higher numbered pick you use that leaves a noticeable “scratch” is determined to be that concretes Moh rating. It is recommended to test multiple areas of your project.

It is of vital importance to conduct a concrete hardness test. It will help you to select the correct diamonds for your surface prep, saving you time and money.