Aggregate Map
This U.S. map highlights the general hardness of aggregate types by geographic region.
- Red areas (e.g., California, Arizona) feature granite, slate, traprock, basalt, and quartzite.
- Brown areas (e.g., Louisiana, Mississippi) contain hard chert, quartz, flint rock, and hard river rock.
- Dark blue areas (e.g., Wisconsin, Indiana) showcase pit gravel, limestone, and dolomite.
- Light blue areas (e.g., Kansas, Missouri) include soft limestone, sandstone, dolomite limestone, siliceous rock, and soft shell.
- Yellow areas (e.g., New Mexico, Colorado) consist of medium-hard river gravel, medium traprock, decomposed granite, and medium crushed gravel.
The type of aggregate in concrete or asphalt significantly impacts the performance and choice of diamond blades and drill bits. Aggregate comprising stone, gravel, and sand—varies by geographic region and can even differ within the same location.
Mineral hardness refers to its resistance to abrasion and is measured using the Mohs hardness scale. This scale assigns values from 1 to 10, with increments of 0.5, where 1 represents the softest mineral and 10 the hardest. The standard minerals for this scale are as follows:
- Talc
- Gypsum
- Calcite (soft limestone)
- Fluorite
- Apatite
- Feldspar (found in some river rock and granite)
- Quartz (present in certain river rocks, granite, basalt, and trap rock)
- Topaz
- Corundum (includes flint, chert, trap rock, and basalt)
- Diamond
A mineral can scratch those with a lower hardness rating but cannot scratch any mineral with a higher rating.
This map provides a general overview of the types of aggregate found in each geographic region, ranging from soft, abrasive materials like talc to hard, non-abrasive materials like flint or chert, as well as various medium to medium-hard aggregates in between. It illustrates the typical aggregate hardness likely to be found in each state but should only be used as a general reference when selecting blades for sawing and drilling. While aggregate size and type can vary widely within a specific area, certain types tend to dominate in particular regions due to local material availability. However, with the increasing transport of aggregate between states, variations are becoming more common. This map serves as a guide to the most commonly found aggregates in each area.
Once the aggregate type is identified, other factors to consider when selecting a diamond blade for sawing and drilling concrete include the aggregate size and the age of the concrete. Concrete typically contains sand, either natural or quarried, and is often reinforced with steel rebar. These factors are crucial, as even minor variations in any of these elements can affect both the cutting speed and the durability of the diamond blade.
Finally, it is essential to consider both the equipment being used and the operator’s technique. The equipment’s age, condition, power rating, and recommended RPM should align with the selected blade, just as the blade must be compatible with the aggregate being cut. Additionally, cutting techniques evolve with experience, and adapting cutting methods to suit different types of aggregate is a key factor in achieving optimal performance.
