Epoxy Repair of Concrete Floors
Industrial Floor Maintenance with Epoxy
Preventing and Fixing Deteriorating Floor Joints and Potholes
It is said that there are two types of concrete floors, those with cracks and those that are going to crack.
Cracks and potholes in plant and shop floors are a major problem to safety and
aesthetics. Here we will discuss what causes them. We will also discuss how to repair them
quickly and economically. For those floors that have not cracked we will discuss
how to minimize or prevent the cracking and potholes.
It is a common misconception that heavy loads on the floors cause most
flooring problems, and so it cannot be prevented. If you are building a new
plant or shop floor there are steps that will help to prevent most flooring
problems. For existing flooring problems we will discuss how to fix the problems and prevent the problems from
Causes of Cracking and Potholes in Shop Floors
Most concrete flooring problems are caused by one of the following:
- Improper installation of the concrete, or poor concrete
- Improperly cut expansion joints
- Steel and hard rubber tires eroding unfilled expansion joints, random cracks and potholes
- Chemical attack
Proper installation of Concrete in New Plant
and Shop Floors
For new construction make sure you specify and get high quality high strength concrete. Create a box-out form around beams, pipes and other
penetrations that go through your floor. Be sure that the corner of your
box-outs line up with the saw-cut joints that you will be putting in the
floor. Penetrations through the concrete cause a "weakened plain". A
weakened plane is typically created at the
shortest distance between the box-outs. That is typically from the corner
of one boxed out area to the next closest boxed out area.
Do not allow your concrete finisher to over finish your concrete.
Concrete finishers tend to over-finish concrete because they are concerned
that if they don't the owner will not like it.
Over-finished concrete does look better than
properly finished concrete until the over finished starts to deteriorate.
The deterioration cause by over finished concrete typically does not take very long
The best finishing of concrete leaves it flat, but does not bring up the
"cream" in the concrete. It will not look as shinny and smooth but concrete that is not over finished will look more
attractive and be more functional over time. Bringing up the "cream" in the concrete is
done by over working the mix or adding too much water or adding water to the
batch. The "cream" consists of dust from the aggregate and Portland cement.
This "cream" creates a great looking finish at first, because it is so
weak, it chips easily. This "cream" has too high a water content,
so you tend
to get micro-cracking in the surface. When your concrete finisher is power
troweling your concrete and starts splashing water into the surface as he is
finishing it he is about to over trowel the concrete and bring up the cream.
It is time to get the concrete finisher to stop troweling.
Water curing of the concrete is what most state highway departments
require to cure concrete bridge decks. Wet curing is
favored over other methods by the US Army Corps of Engineers. Wet curing will help to stop the top of your
concrete from drying out too fast. If you cure with a curing compound
instead of water, you will need to remove the curing compound to install
high quality coatings and sealers.
Proper curing will help to prevent "curling"
of the concrete slab, and help to prevent micro-cracking (crazing) of the
surface. Curling is caused when the top dries and shrinks before the concrete
underneath dries and shrink. This works much like a bimetallic strip
used in a thermostat, the concrete will twist upwards or curl. Proper curing
helps to prevent concrete curling and the cracking that will result from it. Another major advantage of wet cured concrete that is not
over finished is that there is much less surface preparation required when
you go to coat or seal it.
Cut expansion joints often enough, wide enough, and deep enough.
Typically the best way to cut concrete down to 16 foot by 16 foot
squares or even smaller. The larger the
spacing between saw cut joints the more likely you are to get a random crack
where you do not want it. The concrete should be cut-up as square as possible. Care should be taken that all the saw cut joints line up with each other in
a checkerboard pattern. Be sure the cut is at least 1/3 of the way
through the slab, and that the cracks are 1/4 inch or wider. That way
all the plastic shrinkage (drying) cracking should occur under the saw-cut relief joint.
Using Epoxy to Protect New Plant Shop Floors
Seal or coat the concrete to protect it against wear and chemicals.
Epoxy.com Product #223 Water Based Curing Compound, Sealer and
Bonding Agent is a two component water based epoxy curing that is used
to both cure and seal concrete.
Epoxy Primer and Sealer Product #12 -
is a two component, seamless 100% solids epoxy primer system with High
Chemical Resistance Epoxy and High Bond Strength. Epoxy Primer
and Sealer Product #12 is an excellent choice for installers that want a
high quality long lasting stand alone floor sealer. Epoxy
Primer and Sealer Product #12 may also be applied as a primer for
most High End Industrial coatings, like Epoxies, MMA, Polyurethane's, etc.
Allow the concrete to dry for 28 days so that most of the shrinkage at
the expansion joint has taken place. Clean the crack thoroughly, then
install a bond breaker "rope" in the bottom of the joint. Then fill the joints with
Epoxy.com Product #11 Saw-Cut Control Joint Filler- www.epoxy.com/11.htm. Epoxy.com Product #11 Saw-Cut Control Joint Filler
is a 100% solids zero (0) VOC, flexible epoxy joint filler for saw-cut
joints of concrete slabs on grade, or to repair existing slabs.
Random cracks and improperly filled expansion joints are where the
potholes in plant/shop floors are born. As steel and hard rubber
wheels pass over these unfilled cracks and joints it hammers the edge of the
crack in the direction of the travel. This action cause small chips.
As the process continues small chips become larger chips. Soon you
have a small pot hole and the damage continues to accelerate.
Product #11 Epoxy Saw-Cut Control Joint Filler absorbs the impact and shock of
heavy loads and steel wheeled traffic, preventing erosion of control joint
edges. Epoxy.com Product #11 prevents the "jack-hammer" effect on the joint that you
are traveling towards. This will help prevent most if not all of the
"pot-hole" effect that most plant floors see developing at their expansion
joint over time.
In addition to the Epoxy Primer and Sealer Product #12,
you need a moisture tolerant primer to seal your floor using a 100% solids epoxy use
Epoxy.com Product #899 -
www.epoxy.com/899.aspx for sealing the concrete. Epoxy.com also has a
wide variety of shop floor coatings and trowel down systems. Contact
Epoxy.com Technical Support Department with your specific needs for a
Repairing Random Cracks in Floors with Methyl Methacrylate
Random cracking in plant / shop floors can easily and economically be
repaired with Liquid MMA Polymer Crack
Repair Resin Product #684LV a penetrating gravity feed crack healer for concrete.
It is a two component Methyl Methacrylate resin system that polymerizes in
place. The extremely low viscosity will penetrate into concrete cracks as
fine as 0.003 inches. Epoxy.com Product #684LV welds the crack back together
making the concrete as strong as it was before it cracked.
Repairing a Shop / Plant Floor with Epoxy
After it is Damaged
For those who have already built their buildings you can still fill all
the joints especially in the traffic areas with Epoxy.com Product #11 -
www.epoxy.com/11.htm. Filling the
joints with Epoxy.com Product #11
will prevent additional potholes from forming in areas where there are none
To fill the "potholes" in level areas you will typically want
Product #10 Lo-Mod Epoxy
Adhesive and Mortar Epoxy Binder is a 100% solids epoxy has a
low modulus of elasticity (flexibility) and is Low Viscosity. An adhesive
used as a binder for epoxy mortar systems in patching and grouting
applications, as a seal coat for non-skid surfaces outside, and as a primer
to insure high bond strength for coatings and patches.
Product #10 Lo-Mod Epoxy Adhesive and Mortar Epoxy Binder is
also excellent for larger projects or
surfaces that have a slope so you cannot use a self leveling material should
use Epoxy.com Product #10 -
www.epoxy.com/10.aspx and Epoxy.com Product #82 Mortar Blend Aggregate.
With the right mixing equipment you can put up to 100 pounds of #82 into 1
mixed gallon of Epoxy.com Product #11. That gives you a nice stiff
mix, and excellent economy. Epoxy.com Product #10 is a low-mod material,
with high strength. That makes it perfectly suited for outdoor
patching. Epoxy.com Product #10 is the best material for most large jobs.
If the concrete has a lot of pitting in it, you can apply a
"scratch-coat". A "scratch-coat" is done as
1. Carefully measure epoxy resin and hardener. Mix
for 3 minutes.
2. Add aggregate to the mixed resin and hardener
above, and mix completely.
3. Pour out the epoxy resin hardener and aggregate
blend onto the concrete.
4. Then pull a very tight troweled coat over the entire
surface, filling the low spots while scraping as much epoxy resin and
aggregate material as possible away from the high spots.
The material for a "scratch-coat" is with Epoxy.com Product #10 -
www.epoxy.com/10.htm and Epoxy.com
Product #78 Self-Leveling filler. Epoxy.com Product #10 and Product #82
mortar blend aggregate is the best blend for building ramps and smoothing uneven
transitions between slabs.
Just because your floor is already damaged by chemicals, doesn't mean it
is too late. Most floors can be saved with proper patching (as
discussed above) and a chemical resistant
flooring system installed over the patching system. Contact Epoxy.com Technical Support for assistance.
Additional Related Reading
The installation of these materials above are beyond the
scope of this page. Here are some areas to explore this in more detail:
Do with Epoxies
Chip Flooring Installation Guide
Coating Installation Guide
Calculator - for roller applications
Links to popular systems used in residential and commercial
construction resin work
Air Plane Hangers and Garages
Outside Decks and Drive Ways