Decorative Jim Cuviello, Contributing Writer
Knowledge of diamond abrasives widely used are superabrasives made from cubic boron
nitride and synthetic diamond.
used for concrete grinding and
polishing will help you choose Grit particulate is bonded together by various bonding
the best product for your job. material to form an abrasive. Abrasives may be made
through an injection process, hot and cold pressing, elec-
brasives are the most important tool for mechani- troplated and vacuum brazed. The two primary bonding
cally processing concrete to a polished ﬁnish. materials used are metal and resin.
They come in many forms, shapes and sizes and Metal abrasives are made from a blend of micro-graded
are made out of various materials whose bonding varies granulated metal oxides and/or powders. Harder metal
in hardness. Many people think a densiﬁer is required to bond abrasives are made from cobalt, brass and titanium.
create a polished ﬁnish — a densiﬁer will increase the Softer bonded metal abrasives may be made from copper.
durability of a polished ﬁnish and aesthetically improve it, Metal bond abrasives are used in coating removal and
but it is not required to achieve a polish. medium to heavy grinding. Use high grit metal bonded
There are multiple variables and conditions that need tools on softer concrete.
to be considered when choosing your abrasives, includ- Resin abrasives are made from poly-phenolic and ester-
ing physical make up and the conditions they will be used phenolic for wet and dry use and thermoplastic-phenolic
under (see Sidebar on page 26). The manufacturer of the resins for dry use only. They are ideal for light grinding,
abrasive should be able to give you guidelines on how their honing and polishing. Also on the market are hybrids
abrasives best work under certain conditions. Always keep that are made from a combination of bonding materials
in mind the material you are abrading (concrete and aggre- and ceramics. These are used for light to medium grind-
gate, glues, mastics, coatings) has to work together with ing, removal of heavy metal bond scratch patterns and
your abrasive. Not using abrasives properly will affect both offer heavier grinding ability with the ﬁnesse of a resin
their performance and life. bond abrasive.
Abrasive particulate can be coated or uncoated. Since the Abrasives come in several hardnesses of bonding
concrete polishing industry primarily uses uncoated abra- ensuring that diamonds are exposed most efﬁciently for
sives, coated abrasives will not be discussed. maximum cutting. The concrete and the aggregate in the
concrete will determine the hardness of the abrasive bond-
Grit ing for the most efﬁcient cutting. Hard concrete will require
Abrasives are made of a bonding material and particles a softer bonding so that new abrasive grit is exposed for
called grit. Grit is measured in micrometers (also called maximum cutting. Soft concrete will require a harder bond-
microns) and assigned a numeric value based on its size. ing. Soft concrete produces very abrasive particulate that
The smaller the grit designation, the larger the grit particle rapidly wears the bonding. The harder bond slows down the