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**MICK the Tiler** · 01-04-2008

What You Should Know About Masonry - The Manufacturing Process

Brick manufacturing today follows fundamental procedures pioneered centuries ago. However, better knowledge of raw materials and their properties, better control of firing and improved kiln designs have resulted in a superior product. The production of bricks centers around the type of clay that is used. Clays occur in three forms (Surface Clays, Fire Clays & Shales). Although they share similar chemical compositions, they will differ in their physical characteristics. All properties of brick are affected by the composition of the raw materials and the manufacturing processes. Essentially brick are produced by: (1) mixing ground clay with water, (2) forming them into desired shapes, (3) then drying and firing them. Establishing a homogeneous blend is necessary before subjecting the mixture to one of three forming processes (Stiff-Mud, Soft-Mud or Dry-Press). Next, the process continues with drying, firing and cooling. Kiln firing temperatures during manufacturing graduate from 400°F to 2400°F.

Hardness of Bricks

•There are many different types of brick (Building, Facing, Hollow, Paving, Ceramic Glazed and Thin Brick), and different scales of hardness. The strength of a unit is used to determine its durability and cutability. Both compressive strength and absorption are affected by properties of the clay, method of manufacturing and degree of firing. Most bricks have a strengths ranging from 3,000 PSI to over 20,000 PSI; averaging around 10,000 PSI.

•Brick may also include different size, type and volume of aggregates to further strengthen the mix.

What You Should Know About Stone

Natural and Pre-cast Stones vary significantly in their geographic origin, mineralogical composition, and physical and mechanical properties. There are numerous types of stone to select; with each one exhibiting specific qualities of compressive strength and abrasive resistance. Additionally, these qualities would dictate appropriate diamond blade selection to effectively handle cutting requirements.

Your Choice of Stone Requires a Specific Type of Diamond Blade

•Marble
•Sandstone
•Granite
•Limestone
•Slate/Flagstone
•Precast Stones General

Characteristics of Stone

The complex nature and variables of Natural and Pre-Cast stone make it difficult to generalize their overall physical and mechanical properties. Unless the operator has had experience in cutting a particular stone, there are methods that can help predict the stone's sawability, and so determine the "best" diamond blade. The American Society of Testing and Materials (ASTM) recognizes several physical property measurements that can identify a stone's hardness:
•Uniaxial Compressive Strength (UCS) - Measuring basic rock strength parameters. Commonly measured in Pounds Per Square Inch (PSI)

•Cerchar Abrasivity Index (CAI) - Measuring a rocks abrasivity for determining cutting wear rates. Defined by a graduated numerical scale: lower numbers indicating less abrasive qualities, and therefore greater hardness.

•Mohs Hardness Scale - A scale of hardness applied to minerals that ranges from 1 to 10 indicating one from the other's scratch potential. The higher the number the harder the mineral.

•Shore Scleroscope Hardness Test - A dynamic indentation hardness test using a number to indicate the height of a rebounding hammer off the surface of the material. The higher the number the harder the material.
It is recommended to review all data relating to a stone's hardness and abrasive qualities to effectively choose the proper diamond blade. No singular Property Measurement Test can define the characteristics a stone would exhibit during the cutting process. As a general reminder for stone diamond blades: tests and industry experience has documented that stone exhibiting a greater degree of hardness and abrasive resistance require softer bond matrixes.

Conclusion

The preceding information has illustrated the unique physical properties of common building materials that often require sawing or drilling. Over the years, diamond blades and tools have consistently demonstrated their reliability, economy, performance and safety. The singular most important factor an operator of diamond blades and tools can recognize is matching the proper blade with the material to be cut.