The success of your concrete floor grinding comes down to selecting the right tools for the job including the right grinders and blades. Concrete grinders use diamond pads to grind down the concrete with hard synthetic diamonds, they come in a variety of grit sizes and types so it can be slightly confusing knowing which to pick.

Here’s our guide to choosing the correct diamond blades for your concrete grinding job.

Diamond grit sizes

Grit is measured in micrometres and given a numerical value based on its size. The smaller the grit number the bigger its size so, a 30 grit pad will have bigger diamond particles than a 100 grit pad. In a lot of concrete grinding jobs such as floor grinding, 30 to 40 grit pads work well to start. You can then move up to finer grit sizes. If you’re working on a polishing job, use 60 to 80 grit next and continue increasing up to 3000 grit until you achieve your desired look.

As a general rule, use 30 to 40 grit as a prep grit, 18 to 20 as an aggressive removal and 80 to 100 for polishing. Choose a finer grit after this if you still want a more polished concrete floor.

Bonds

The bonds of your grinding tool are what hold the diamonds in place and to get the right finish on your concrete floor, the bonds need to break down at the correct rate to release new diamonds at the right time. Grinding is a mutually abrasive process of both the tool and the concrete, so the wear rate of the tool should be equal to the wear rate of the slab. The bond should match the size of the diamond to allow the bonds to wear and expose new sharp edges of the diamond.

Hard vs. soft concrete

You need to take into account whether the concrete you’re grinding is hard or soft as this will affect the type of diamond abrasives you need to get. By choosing the right grit for the concrete, you’ll ensure the pad lasts longer. For example, using hard diamonds to grind hard concrete will not produce the desired result because grinding hard concrete doesn’t produce much sand. So, when the diamonds break and blunt, the metal bonding around them is not worn away as easily meaning the diamonds do not become as exposed as they would with soft concrete, which produces more sand during grinding. 

If you are grinding hard concrete, it’s better to use a lower grit size, around 20 and a soft bond, so that the bond and the diamond wear down at the same rate. 

Concept Flooring Technology offers a wide range of grinder consumables including diamond blades for concrete grinding in a variety of grit sizes. We also offer flooring machine hire to help you get the job done. Contact our friendly team today to find out more.