How Do You Fix Garage Floor Spalling and Pitting?

Concrete floor spalling is a garage floor problem where the thin top layers of concrete separate from the rest of the surface. The layers come off in small sheets or flat little chunks. Concrete floor pitting is where the concrete has lots of small holes. How do you fix concrete garage floor spalling and pitting?

To fix spalling and pitting, remove weak concrete adjacent to the damage; clean and prepare the surface to be repaired; finally, patch the area with an epoxy-based topping. However, if there is a serious moisture or structural issue, bring in a professional repair company.

How Spalling and Pitting Form on the Garage Floor

Spalling is a de-layering of the concrete surface that happens over time.

Moisture works its way into the concrete. Concrete expands and contracts with the freeze-thaw cycle. Extreme temperatures and exposure to de-icing salts work their magic to damage the concrete. Microscopic damage from water particles causes fractures in the concrete. The fractures break into fine dust at the surface.

Sometimes spalling can be an indication of deeper issues such as a moisture barrier problem. If you suspect that the issue is deeper than extreme freeze-thaw cycles and/or exposure to road salts then you should check for moisture (see below for instructions).

Pitting is a set of random small holes in the concrete surface that has many causes. Pitting can be caused by temperature changes, frost, concrete additives, and application mistakes.

Pitting is not usually a sign of a deeper moisture issue. But if such a problem exists, pitting repairs will fail.

Clues to Deeper Water Problems

Before fixing spalling or pitting, check for water issues that might require professional help to fix. There's no point in fixing a concrete problem that will just come back.

Here are some signs of potential water problems:

• A chalky white stain called “efflorescence.” This happens when water and salt seep through the floor. The evaporating water leaves the calcium chloride (salt) behind. The stains themselves are not a problem and can be easily cleaned, but they could be an indication of moisture issues.
• A constantly damp area on your garage floor
• Use a moisture meter to check for leaky pipes
• Look for water spots after heavy rains

These are indications that there is an ongoing water problem affecting your garage floor. No repair can withstand the constant onslaught of more water. You'll need to address the water problem before repairing the floor.

Address Garage Floor Moisture Problems Before Repairing the Spalling and Pitting

WARNING! It is important to address any moisture problems before you do any kind of epoxy surface treatment.

Water will come up through the porous concrete and will accumulate under the non-porous floor coatings. That is, if the coating on your floor does not breathe, the water coming up through the floor will not evaporate. It will cause pressure build-up in the concrete that will end in spalling and pitting.

Under extreme circumstances, when the floor is covered with an ultra-heavy-duty epoxy coating, the pressure can build up to the point where chunks of floor can come popping out. Rather than letting the moisture breathe, heavy sealers cause the water pressure to build.

Rather than take that risk, apply the relatively simple moisture tests before applying spalling repairs.

Test for Garage Floor Moisture Using Plastic and Tape

If you suspect a moisture problem you can do this simple test.

Get a piece of Saran Wrap about 16 x 16 in. square. Place it on the garage floor, and seal the edges with duct tape or Gorilla tape. Wait 24 hours.

If there is a dark spot where moisture has accumulated, or if there is water on the underside of the plastic, then there is probably a moisture problem that requires professional attention.

If it’s dry then it's OK to repair the spalling.

Test Garage Floor Moisture With a Calcium Chloride Moisture Kit

If the plastic sheet test came back positive for moisture, you will then want to get a calcium chloride moisture kit.

To use a calcium chloride moisture kit:

1. cut a new piece of plastic wrap
2. place the calcium chloride kit on the floor, and cover it with the plastic
3. tape the plastic edges
4. wait 24 hours
5. weigh the dish on the scale that comes with the kit
6. use the chart on the box to determine if the floor has more moisture than it should
7. if it does, the kit will point you in the right direction for your next steps

How to Use an Epoxy-Based Garage Floor Repair Kit

Epoxy repairs tend to fade into the concrete so they're not noticeable once cured. However, epoxy is a pain to use, so you should know before you start what you need to do. Epoxy can become unusable in as little as 15 minutes.

All epoxy products (even the ones that come in a single tube with a mixing nozzle) come as separate ingredients that you mix together.

• With two-part epoxy, you mix together resin and a hardener.
• With three-part epoxy, you mix resin, hardener, and an aggregate or sand.

You must measure the parts carefully to get the right bond. Plus, you must use the mixture quickly, because epoxy has a limited “pot life.” It will harden up before you know it, and you'll have to throw away that batch and start over.

Plan ahead. Mix only what you will need for the next part of the project. Give yourself less time than the instructions indicate. It is better to mix smaller batches more often than to throw away an expensive product that became too hard to use.

The Best Parts of Epoxy Floor Patching

• Epoxy-based materials are durable. They provide long-lasting repairs that can withstand heavy traffic and mechanical stress.
• Epoxy materials have excellent bonding properties. They adhere well to the existing concrete surface.
  Epoxy is resistant to various chemicals, including oil, gasoline, and other automotive fluids commonly found in garages.
• Epoxy can be pigmented and applied in a variety of colors, allowing you to achieve a visually appealing and uniform surface.
• Epoxy-based patching materials are attractive and easy to clean.

The Less Attractive Aspects of Epoxy Floor Patching

• Epoxy-based materials are usually more expensive than other concrete patching options.
• Epoxy typically requires multiple steps for proper installation, including surface preparation, mixing, and curing time. This process can be time-consuming, especially for larger areas. But to be fair, this is roughly true for all concrete repair solutions.
• Epoxy materials are temperature-limited. You should wait for weather between 45 and 90 deg. F. before using an epoxy patch. Extreme cold or hot weather conditions affect curing and adhesion.
• Epoxy is sensitive to ultraviolet (UV) light, which can cause it to yellow or deteriorate when exposed to sunlight. This is a concern if the garage floor receives direct sunlight.

Step-by-Step Guide for Repairing Concrete Garage Floor Spalling and Pitting

Spalling and pitting require slightly different preparation tasks. Read each step to see which applies to your specific garage floor.

Step 1: Remove Weak Adjacent Areas

This step applies to spalling but not pitting. For pitting, go to the next step.

Spalling damage starts below the concrete surface. Not all damaged areas may be visible. If you want to properly fix a floor damaged by spalling, you want to look for areas around the visible damage that may be weak enough to break free on their own.

For this step, you need a hammer and a pair of safety goggles.

1. Wear safety glasses
2. Use a hammer to tap around areas that are adjacent to the visibly damaged area.
3. Listen for a hollow sound. This will indicate that there is damage just below the surface.
4. Hit those areas hard so that they break free. You want to expose the damaged areas so you can repair them.

If you don’t break off the weak concrete, they will be the spots for next year's repairs. Finding and repairing them now will save you time and money. Especially if you intend on painting or treating your floor in the future.

Step 2: Clean the Prepared Area

If you have spalling, come here after finishing Step 1. If you have pitting, welcome to your repair instructions.

Clean the area you are about to repair. To clean the damaged areas, remove the loose material as follows:

1. use a wire brush to loosen weak areas
2. build up the edges inside the damaged area to get the best possible repair
3. sweep and vacuum the damaged area until all of the loose pieces are gone

You want to give your repair something stable and solid to adhere to, so don’t skimp. Proper prep work is the heart of this kind of repair.

Step 3: Use the Appropriate Size Kit

• For small repairs, use Rust-Oleum Concrete Patch and Repair (view on Amazon.com).
• For large repairs, use Rust-Oleum TurboKrete (view on Amazon.com).

Step by Step Instructions to Patch a Small Area with Concrete Patch

Here's how to patch the damage using epoxy for smaller areas of pitting or spalling.

You will need:

1. safety goggles
2. rubber gloves
3. an epoxy patch for concrete such as Rust-Oleum's EpoxyShield Concrete Patch and Repair (view on Amazon.com)
4. a piece of cardboard (or wood)
5. a trowel
6. optionally an orbital sander along with 60-grit, 120-grit, and 200-grit sandpaper

To repair the small area of spalling or pitting using Rust-Oleum Epoxyshield:

1. be prepared. You have no more than 30 minutes, often less, before the epoxy hardens
2. wear gloves and goggles
3. use the trowel to mix the hardener and resin on the cardboard or wood
4. trowel the epoxy onto the damaged area
5. level the epoxy
6. wait 2 hours to apply a second coat
7. allow 8 hours to cure
8. optionally sand the epoxy with 60, 120, and 200 grit sandpaper in succession

Step by Step Instructions to Patch a Large Area with TurboKrete

Here's how to patch the damage using epoxy for larger areas of pitting or spalling.

You will need:

1. safety goggles with side shields
2. rubber gloves
3. an epoxy patch for concrete such as Rust-Oleum's TurboKrete (view on Amazon.com)
4. the TurboKrete bucket for mixing the parts
5. a 1/2 in. drill
6. a birdcage mixing attachment (like this mortar attachment on Amazon.com)
7. paint brush
8. handheld streel finishing trowel
9. Rust-Oleum 160 thinner
10. optionally an orbital sander along with 60-grit, 120-grit, and 200-grit sandpaper

To repair the larger spalling or pitting area with TurboKrete:

1. ensure the temperature is between 45-90 deg. F.
2. be prepared. You have no more than 30 minutes, often less before the epoxy hardens
3. wear gloves and goggles
4. combine part A base epoxy resin with part B activator in the TurboKrete bucket
5. mix the resin and activator using the 1/2 in. drill and mortar or birdcage attachment
6. if the area is less than 1/2 in. deep, use this A+B mixture and the paintbrush to prime the repair area
7. at a uniform rate, add the aggregate to the resin + activator, and mix with the drill and attachment
8. apply the mixture to the patch using the steel trowel
9. spread and flatten the repair
10. add the 160 thinner to the trowel
11. using the trowel, feather the material to a thin layer at the repair area edges
12. let dry for 4 hours
13. clean tools with the 160 thinner