Hardness test for concrete surfaces
To determine the hardness of a concrete surface, in relation to the Mohs hardness scale, a scratch test can be performed, see the Scanmaskin The concrete test kit. Start with the lowest numbered pick, and work your way up until you can create a scratch in the concrete. Once you determine the corresponding number, this gives you the value in relation to the Mohs scale.
The Mohs hardness scale indicates the scratch resistance of different materials in that a harder material is able to scratch a softer material. The method was created in 1812 by the German chemist and mineralogist Friedrich Mohs (1773 –1839).
The Mohs hardness scale is divided into a scale that goes from the softest material to the hardest material on earth, diamond, which has number 10 on the scale. For example, corundum (9) is twice as hard as topaz (8), while diamond is four times as hard as corundum.
- Talc
- Gypsum
- Calcite
- Fluorite
- Apatite
- Feldspar
- Quartz
- Topaz
- Corundum
- Diamond
Make your tool selection easier with The concrete test kit
Make your tooling choice easier with the Mohs hardness test kit for concrete. The concrete test kit, from Scanmaskin, helps you to determine the hardness of the concrete surface in relation to the Mohs scale and thereby makes your tooling choice easier. This helps to increase productivity and reduce tool wear.
Make a simple scratch on the concrete surface and you will get the hardness of the concrete according to the Mohs scale. Start the test with the lowest number pick, then work your way up until the surface starts to scratch. See what number the pick has made the scratch and choose the bond of your tool accordingly. Note that this is just a guideline for your tooling choice.
Mohs scale Bauta Double
2-3 SCXXX Extremely hard diamond tool for freshly poured concrete
4-5 SCL Hard diamond tool for normal concrete, longer lifespan
6-7 SCS Soft diamond tool for hard concrete
8-9 SCSSS Extremely soft diamond tool for glossy hard surface
WORLD SERIES DIAMOND TOOLS
2-3 BLACK Extremely hard diamond tools for soft floor.
3-5 BLUE Medium hard diamond tools for normal floor.
5-7 GOLD Soft diamond tools for hard floor.
7-9 YELLOW Extremely soft diamond tools for extremely hard floor.
Grit describes the grain size
Grit is used when describing the grain size of the diamonds in the tool, often shorten with # in descriptions. The grit number indicates the size of the diamond grains. The lower the number, the bigger the diamonds, and vice versa. If you grind a concrete surface in several steps, it is important that the diamonds are able to remove the scratches from the previous step. This may vary depending on the hardness of the concrete floor. Feel free to compare it with sandpaper that everyone knows.
Polishing concrete means processing a concrete surface
Concrete polishing is the process of refining a concrete surface until the desired refinement is achieved. The term ”concrete polishing” is used loosely and can include everything from a two-step grind and seal to an eight-step mirror finish. It’s all about refinement – polishing a surface means that one starts with a rough diamond tool (low grit number) or abrasive profile and refines this into a smoother profile (high grit number) until maximum refinement is achieved. A very common mistake is to skip refinement levels and rush the process. That only causes excessive wear on the diamond tool and usually takes much longer overall. It’s easy to break up the process of concrete polishing into three main components:
- Grinding
- Honing
- Polishing
What does glazing mean in connection with concrete grinding?
Check and measure the diamond tools before you start grinding the concrete floor. Is it open and sharp? If the diamond tools wear more than 1 mm in 30 minutes, you should choose another diamond tool.
Is there a risk of glazing?
Glazing in connection with concrete grinding means that the surface of the concrete becomes shiny and hard instead of being dull and porous. It can be caused by improper grinding with the wrong diamond tool or too high a speed.
Cross-hatching – a way to operate the grinder
Cross-hatching (ea, operating the grinder in a North to South then East to West grid pattern) is always recommended, both when changing grits and also when performing more than one pass per grit. Cross-hatching provides more consistent refinement across the surface and helps avoid visible lines in the floor, sometimes referred to as “cornrows”. In addition to cross-hatching, using a diagonal pattern to create a third cutting angle can also improve the refinement process.