When flooring failures occur, the
initial reaction is to point the finger of blame at the
installer or flooring material manufacturer. Well, look deeper
as the stage often has been set for failure before the installer
The flaws often begin to occur at
the base with your concrete slab. Many finishers overwork the
concrete surface, usually by keeping powered trowel equipment on
the concrete surface too long. We call this over-finishing. It
densifies the concrete surface to the point that adhesion
between the concrete slab and installed floor isnít adequate.
You can see the evidence prior to installing the flooring as the
concrete appears slick, smooth and darkly colored. Thatís the
sign that costs are about to run up as resurfacing the newly
finished slab delays the project and results in paying for the
job a second time.
This is a common mistake as many finishers (with the best of
intentions) try to make the concrete as smooth as possible in
prepping for floor installation. Hereís how to insure the job is
done right the first time. Simply add some form of the following
language to your concrete specification:
Smooth, hard, hand
steel-troweled finishing is preferred. Machine-troweled
finishing free of trowel ridges is accepted.
Produce a tight float finish,
the machine equivalent of hand wiping the surface with a
Avoid burnished and polished
concrete surfaces that may impede mechanical bonding of
subsequent coatings, toppings, underlayments, absorption of
flooring adhesives and floor finishes.
Finish to specified
tolerances. Do not burn or overwork concrete.
Do not blacken or burn
concrete surface with power trowel.
Of course, the best recourse
for the facility manager is to have a qualified person
monitor the slab finishing process.
One way to ensure the individual
is qualified is to use a technician who is certified by the
International Concrete Repair Institute. These trained techs can
help prevent over-finishing, and other common concrete errors ó
such as conducting moisture testing before the building is
climate controlled. ICRI technicians are trained for, among
other things, moisture testing per ASTM-F2170, The Standard Test
Method for Determining Relative Humidity in Concrete Floor Slabs
Using In-situ Probes.
Aside from reducing rework, thereís another way to save on
concrete costs. Using a rapid drying concrete can reduce your
overall project duration up to 30 percent. This in turn reduces
the overhead costs to the general contractor and offers
speed-to-market benefits to the project owner.
About the Author:
James Tyrone is Aridus
program director for U.S. Concrete.
This post is part of an ongoing
series from the IFMA Health Care Institute. To download the full edition of
Tips, Tricks & Traps to Avoid,