How to Repair a Concrete Crack with Epoxy InjectionHow to Repair a Concrete Crack with Epoxy Injection How to Repair a Concrete Crack with Epoxy Injection
How to Repair a Concrete Crack with Epoxy
Injection
Homeowners love how a concrete basement provides a safe, clean and dry
area to store possessions or expand a home's living space. What they don't love
is how concrete cracks. Cracks in a basement wall can let in water or signify
that there is a structural problem with the foundation. Injecting a basement
wall crack with epoxy will stop any water leaks and structurally repair the
wall.
Epoxy Crack Injection Advantages
- Seals the crack from
water
- Epoxies are stronger than
concrete
- Structurally repair the
concrete
All Concrete Cracks
First, the basics. All concrete basement walls crack. These cracks are
due to the concrete shrinking as it cures and the water in the mix is removed.
This shrinkage places stress on the concrete and to relieve that stress, the
concrete cracks. The cracks will develop soon after the foundation is cast in
place. The vast majority of cracks are not a sign of a structural defect with
the foundation.
Structural Cracks in Concrete Basement Walls
While it is difficult to determine by looking at a basement wall crack
if it is in fact a structural problem, there are a few rules to help guide you.
If the crack is over ½" wide there is a chance that it is a structural
crack. Horizontal cracks are almost always a structural problem. Cracks that
run on a severe diagonal, especially those that start at an inside corner are
usually a structural issue. It should be noted that diagonal cracks that start
at the corner of a window or where the foundation "steps down" and
are under ½" most likely are not a structural issue.
If you are not sure if a crack is structural in nature, an engineer can
be hired for a few hundred dollars to determine it for you. The engineer may
use a crack stress gauge to help in determining if it is.
Signs of a structural crack
- > 1/2" in
width
- The crack is
horizontal
- The crack runs on a severe
diagonal
How the Concrete Basement Wall Crack is Repaired
The repairs made to a basement wall crack are performed from the inside
of the basement. Epoxies are injected into the crack in a liquid form. The
epoxies are a two component material that is mixed as they are injected into
the crack. After mixing they will cure to form a hard and strong material to
reinforce the wall. In fact, the epoxies have a higher compression and tensile
strength than the concrete itself. Once the epoxy has cured the crack will not
leak water.
How the Epoxy Injection is Performed
Step 1.Attach Surface Ports - Plastic
injection ports are attached with a special surface paste directly over the
crack. These ports are spaced every six to twelve inches.
Step 2.Seal the Crack Surface - Once the ports
are attached, the rest of the crack is covered with the same special surface
paste. This is not what makes the crack water proof. It merely keeps the epoxy
in the crack as it reacts and hardens.
Step 3.Injecting Epoxy into the Crack - The
injection process starts at the lowest surface port. A mixer that attaches to
the epoxy cartridge is inserted into the port. The epoxy is in a liquid form
and flows into the crack. It will flow all the way to the outside surface of
the crack. Once you see the epoxy start to come out of the next port above you
stop injecting into the current port and move to the one above. A plug is
inserted into the first port to keep the liquid epoxy from leaking out. Proceed
until all of the ports have been injected.
Epoxy Cure Time
Epoxies start to cure as soon as the two parts are mixed. They start to
reach a semi-rigid gel after about 20-30 minutes. After several hours they will
start to become hard. Final cure strengths are usually achieved after seven
days.
Limitations
- Not for concrete block
walls
- Not for use on floor cracks
