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Concrete Cutting Diamond Tools

How Diamond Tools Work

Diamond blades don't cut they grind! The exposed diamond crystals do the grinding work. The metal matrix or bond holds the diamonds in place. Trailing behind each exposed diamond is a "bond tail" which helps to support the diamond. As the blade rotates through the material the exposed surface diamonds grind.

After several thousand passes through the material being cut the exposed diamonds begin to crack and fracture. The matrix holding the diamond also begins to wear away.


Eventually the diamond completely breaks up and it's fragments are swept away with the material that it is grinding.

As the old diamonds are worn down they are replaced by new ones and the process continues until the blade is worn out.

Factors that effect performance

Compressive Strength:
Concrete Hardness PSI Application
Critically Hard 8,000+ Nuclear Power Plants
Hard 6-8,000 Bridge Piers
Medium 4-6,000 Highways
Soft 3,000 or less Residential & Commercial Building
Concrete may vary greatly in compressive strength which is measured in POUNDS per SQUARE INCH (PSI). Most concrete roads are approximately 4-6,000 PSI, while typical patios and sidewalks are about 3,000 PSI.
Type of Sand:
Sand is the component of the mix which determines the abrasiveness of the concrete. Sand can either be "sharp" (abrasive) or "round" (non-abrasive). Crushed sand or bank sand are usually sharp; river sand is usually round.
Size of Aggregate:
Larger aggregates tend to make a blade cut slower while smaller aggregates tend to allow a blade cut faster. The most common aggregate sizes are:
Size  
Pea Gravel Usually less than 3/8" in diameter
3/4" Sieved size
1-1/2" Sieved size
Hardness of Aggregate:
There are many different types of rock used as aggregate. Generally hard aggregate breaks down the cutting diamonds faster which means the bond must be softer to expose new diamonds. Softer aggregate generally does not break down the cutting diamonds as quickly and therefore requires a harder bond to hold the diamonds in place to use their full potential. The Mohs' scale is used to estimate hardness:
Moh's Range Description Aggregates
8-9 Critically Hard Flint, Chert, Trap Rock
Basalt
6-7
Hard River Rock, Granites, Quartz, Trap Rock
4-5 Medium Hard Granites, River Rock
3-4 Medium Limestone, Sandstone
Reinforcing Steel:
Steel reinforcing tends to make a blade cut slower. Less reinforcing allows a blade to cut faster. Heavy rebar can also result from different grades of steel. Typical rebar is grade 40 but grade 60 is also common. Rebar gauges are in eights of an inch. #4 is 1/2" diameter, #5 is 5/8" diameter etc.
Size Examples
Light Wire mesh, single mat
Medium #4 rebar every 12" on center each way (OCEW) single mat.
Wiremesh multi-mat.
Heavy #5 rebar 12" OCEW single mat
#4 rebar 12" OCEW double mat
Green or Cured Concrete:
The drying or curing of concrete greatly affects how the concrete will interact with a diamond blade. Green concrete is freshly poured concrete that has not yet cured. It is softer and more abrasive than cured concrete. A harder bond with undercut protection should be used in this application until it is cured at which point a softer bond would be appropriate.The definition of green concrete can vary widley. Water, temperature, moisture in the aggreagate, time of the year and the amount of water in the mix all influence the curing time.
Variables:
Variables
Change
Results
Cutting Speed
Blade Life
The Blade
Segment Bond Hardness Harder
Slower
Longer
Softer
Faster
Shorter
Diamond Quality Lower
Slower
Longer
Higher
Faster
Shorter
Diamond Concentration Lower
Slower
Longer
Higher
Faster
Shorter
Segment Width Thicker
Slower
Longer
Thinner
Faster
Shorter
The Saw
HorsePower Lower
Slower
Longer
Higher
Faster
Shorter
Blade Speed Higher
Slower
Longer
Lower
Faster
Shorter
The Job
Water Volume Higher
Slower
Longer
Lower
Faster
Shorter
Cutting Depth Deep
Slower
Longer
Shallow
Faster
Shorter
Cutting Pressure Lower
Slower
Longer
Higher
Faster
Shorter
The Material
Material Hardness Harder
Slower
Longer
Softer
Faster
Shorter
Material Abrasiveness Less
Slower
Longer
More
Faster
Shorter
Aggregate Size Larger
Slower
Longer
Smaller
Faster
Shorter
Aggregate Amount More
Slower
Longer
Less
Faster
Shorter