The hardness of your concrete is an important thing to know for choosing the proper tooling segment and bond. Matching your tooling to the hardness of your concrete will extend the life of your tooling. Metal bond diamonds on a planetary grinder come in super soft, medium, and hard bonds. A soft bond means the glue holding the diamonds is soft and will wear away quickly, which exposes the diamonds. This type of super soft segment is ideally suited for hard concrete. Exposing the diamonds more quickly gets the diamonds into the work more quickly.
While soft bond diamonds may also wear more quickly, they are much more efficient on the right type of concrete. The reverse of this concept is also true, with a hard bond diamond used on soft concrete. Keep in mind that concrete floors vary significantly. Different parts of the country use different mixes of concrete depending on climate challenges, additionally the life of the floor and any additives or sealers could really impact the hardness.
The shape of the segment on the bottom of your metal bond diamond is also affected by the hardness of your concrete. Pairing an aggressive shape, like the 2-up Micro PCDs with a soft concrete floor will leave deep gouges in the floor. Conversely, a metal bond prep diamond with beveled edges isn’t likely to break the surface tension of a hard concrete floor.
Before you can effectively prep a concrete floor you need to know how hard the concrete is. Take the guesswork out of testing the hardness of your concrete surface by using a pocketknife, or a flathead screwdriver. Using either of these tools, press into the concrete floor and run it back and forth in a straight line pressing lightly into the concrete.
The amount of concrete dust accumulated by this method will indicate the hardness of your concrete surface. If you can’t dig into the surface at all you know it is hard concrete. Just the opposite of this is true with the same test on soft concrete. Soft concrete under this test will immediately dig a trench with very little effort. Additionally, if you make just a small amount of dust with this method, you likely have medium concrete hardness.
To get the most out of your tooling, and to take the most effective approach to grinding your concrete floor, test your hardness before you begin.