Epoxy Concrete Repair
Summary: If you are looking to repair concrete, then epoxy concrete repair by injection might be your best bet. Even though concrete epoxy repair will fill a hole or repair a crack, it might not alleviate what caused the crack in the first place.
If the layer underneath is unstable, then you'll just get more cracks later near or along the epoxy repair patch.
It is also important to know that you should never fill or seal expansion joints because epoxy won't stop normal contraction and expansion and will pop off as soon as contraction or expansion occurs.
If you have concrete that needs to be repaired, you can usually do it yourself and save money.
It's important to read the steps thoroughly so you can be prepared with the proper tools and materials. That way you'll end up with a neat repair job and less waste.
Epoxy concrete repair can be used on hairline cracks, sidewalk or driveway cracks, cracks and holes in concrete walls, holes in sidewalks or driveways, and to repair broken concrete corners.
This guide discusses repairing cracks in a concrete wall.
You will need the following tools and materials for your concrete repairs:
- garden hose
- wire brush
- work gloves
- cold chisel
- binary caulking gun or epoxy injection gun
There are some concrete repairs that are better repaired with epoxy and some that are better repaired with polyurethane foam.
In some cases either of these materials can do the jobs, and the person doing the repair may simply choose the material he or she has more experience with.
Here are some guidelines for when epoxy concrete repair is appropriate:
If fixing a crack is actually accomplishing a structural repair because the area must be as strong as possible, then you should choose epoxy.
Rather, if it's simply a matter of preventing water leakage or sealing a leaking crack, then polyurethane might be best.
Epoxies for epoxy concrete repair are available in many levels of viscosity. Some are very thin, and some have the consistency of paste.
Different ones are used for different sizes of cracks.
The general rule of thumb is to use the viscosity necessary to inject a given crack at a pressure less than 40 psi. In other words, the larger the crack, the thicker the epoxy needs to be.
The advantage of epoxy concrete repair is that epoxies have exceptional compressive strength: 12,000 psi or greater, which is more than the compressive strength of most concrete. That's why epoxies are the best choice that need structural repair.
The main drawback is that epoxies do not cure quickly. They can take several hours to harden. Of course, this can be good because it allows the epoxy to work its way into very small crevices.
Then again, it's also possible for epoxy to flow out of the back of a crack before it has hardened if the backfill has separated from a house foundation, for example.
Epoxy injection is usually the basis for the repair of a structurally significant piece of concrete. Often the epoxy is stronger than the concrete and can restore the concrete's strength.
However, if there is an underlying problem, such as foundation movement or an overloaded structure, then the concrete will crack somewhere else until the problem has been repaired.
The first step in epoxy concrete repair is to clean the crack out using a vacuum or flushing it with water. This gets rid of dirt and contamination.
Next, surface cracks are sealed with epoxy gel to keep the epoxy you'll inject from running out. Next, create injection and venting ports before injecting the epoxy.
Vacuum out all dust in and around the vent hole near the crack. Dust can mix with the injection epoxy and form a paste that can block resin flow.
Likewise, drilling a narrow crack with a drill will drive dust into the crack, which keeps the epoxy resin from flowing into it.
In general spacing of the vent holes should be between four and eight inches apart.
The injection should not be a high pressure injection because it can actually widen cracks.
When you've injected the crack with the proper viscosity epoxy, remove the ports and surface seals by grinding the surfaces so they are flush with the concrete.
The key to effective epoxy concrete repair using injection is the gradual introduction of the epoxy into the crack at low pressures of 20 to 40 psi.
It requires patience, but it lets the applicator keep an eye on the injection process and ensure that the crack is filled thoroughly.
This is crucial, because incomplete injection of a crack is the most common reason for epoxy concrete repair failure.
This is especially true when fixing cracks in foundation walls.
That's because injecting at pressures greater than 40 psi can be ineffective.
When epoxy is injected at a higher pressure, the liquid force can overcome gravity and rise up the crack before the back side of the crack has been reached.
Epoxy Concrete Repair Related Reading
Epoxy Concrete Sealer
Epoxy Concrete Floor Coating
Return to Concrete Repair
Return to MMC Home Page