Safety
and great care must be taken when working with concrete. It is
important to exercise caution when drilling holes in concrete, using the
necessary tools for installation as well as during the actual
installation of these fasteners. Below are some important safety tips to
keep in mind during your next concrete drilling and/or fastening
applications.
Concrete Drilling
Drilling holes in concrete must be done using a hammer drill and a carbide bit.
The concrete is broken up into small pieces by the hammering motion of
the drill and the rotation pulls the material out of the hole. Small
pieces of concrete can fly out of the hole and may enter the eye. It is
always important to wear safety googles when drilling holes in concrete.
Airborne concrete dust may be also be created depending on the dryness
of the concrete- mouth and dust protection should also be considered
when holes are being drilled in the concrete.
Hammer Drills
Hammer
drills are used for drilling holes into concrete and are manufactured
by many large tool manufacturers around the world. It is very important
to follow all of the manufacturer's safety measures for the hammer drill
being used. Most of these hammer drills come with a grounded electrical
cord with instructions on what type and lengths of extension cords
should be used. Many times when drilling holes, the bit may get bound up
in the hole. The larger the hole and hammer drill, the more critical
this is since these drills are very powerfrul with lots of torque. Most
brands of hammer drills have clutches built into them that aloow for the
drill to clutch out if the drill bit gets bound up in the hole. This is
a very important safety feature- make sure that the hammer drill has a
clutch. Most drills are sold with a detachable handgrip that fits on the
drill and swivels 360°. Use the handgrip because it will allow for two
handed operation of the hammer drill. This is critical in the safe use
of this tool.
Concrete Anchor Installation
The
installation of concrete anchors requires numerous tools other than
hammer drills. Once the hole is drilled, there is concrete dust that
must be removed from the hole and the area around the hole. This dust
can become airborne, therefore it is important to wear some type of
mouth and nose protection so that you do not breath the dust into your
lungs. A wire brush, vacuum or compressed air can be used for this
procedure. The wire brush and compressed air can make a large concrete
dust cloud. With the proper safety protection and equipment, you will be
protected from these hazards.
Other Tools
Depending
on the particular type of concrete fastener being used, there are a
number of different tools that are required to set the anchor in place.
Most concrete fasteners require the use of a hammer. It is important to
make sure that the hammer is heavy enough for the job. Large wedge
anchors require a large hammer to anchor into the hole in the concrete.
Some anchors, such as the drop in and machine screw anchor, require the
use of a setting tool. This setting tool is a piece of steel that is
inserted into the anchor and then struck by a hammer setting the anchor
in the concrete. Anytime a hammer is used, eye protection should always
be utilized. Concrete anchors
either have a nut that needs to be turned or a bolt that requires the
use of a wrench. The manufacturer safety recommendations should be also
be followed. The correct size of wrench is also important to consider.
Holding Values of Concrete Fasteners
The
friction created between the anchors and the walls of the hole in the
concrete create the holding values of the concrete. The holding values
of concrete fasteners are broken up into 2 categories- pullout/tension
and shear. The shear values are directly related to the diameter of the
anchor or bolt being used and the depth of embedment into the concrete
as well as the strength of the concrete the anchor is in. The pullout or
tension values of an anchor derive its value from the depth of
embedment of the anchor, strength of the concrete
and the diameter of anchor being used. Each anchor has a minimum
embedment depth that must be achieved for the anchor to have much or
any holding value. Each type of concrete anchor has been tested for
holding values at different embedment depths and strengths of concrete.
Each manufacturer has its own tables outlining these values. Each should
be read carefully in insure the proper choice of anchor for the
particular application. Some of the tables refer to "Ultimate Loads" and
others show "Safe Working Loads". The difference for comparing two
tables from two manufacturers is that safe working loads are 25% of the
ultimate loads. When setting an anchor, it is important not to
overtorque the anchor because is may spin in the hole and not achieve
the holding powers required. Below are links to holding value tables for
wedge anchors, sleeve anchors, Tapcon® concrete screws and drop-in anchors.
Location of Concrete Fasteners
One
of the most critical places to use a concrete anchor is in overhead
applications. If the anchor or concrete should fail, the consequences
could be deadly. If the application calls for overhead installation, it
is imperative that an engineer is consulted. Most cities have certain
codes and these can differ from city to city. These codes should be
checked before installing concrete anchors or beginning a project
Please remember with all fastening jobs to keep safety in mind. Always follow safety instructions on all tools, and refer to manufacturer's installation instructions when available and always remember to wear safety goggles!
Article written by: Michael Pistorino, Concrete Fastener Specialist