How to Repair Cracks on Concrete Floor & Causes

As tough as it tends to be, concrete floors may develop tiny to reasonable cracks and chips. However, the cracks don’t mean there are serious structural inadequacies. Also, the cracks do not disqualify the fact that the concrete floor is resistant to wear and tear, pounding, scouring, and scraping. How can I repair my concrete basement floor? You might be wondering; we got you covered.

Because of the resilience of the concrete floor, it is one of the versatile flooring options used virtually everywhere within the room space. Moreover, they are cheap to install and require little maintenance. One of the maintenance practices is to repair cracks on the concrete floor.

Therefore, you should fix the cracks as they appear to counter any further damage that may occur along the cracks. Sealing the cracks as soon as they appear may save you the time and the extra resource that you may use to work on the enlarged crevices. 

When Should I Repair My Concrete Floor?

The following problems may prompt you to repair your concrete floor.

  1. When cracks appear on the surface of the floor.
  2. When you realize that there are dents left on the surface of the floor. The cuts can either be due to heavy and sharp objects dropping onto the surface of the floor.
  3. Concrete floor crumbling leading to the formation of a hole.
  4. Presence of ridges or humps left by the floor finishers.

The above problems can be present due to other factors such as rapid drying of the concrete, mechanical damage by heavy pounding, pour cement to sand ratio, use of excess water in the concrete mix during concrete laying, and poor craftsmanship.

Causes of Cracks on Concrete Floor

There may be multiple causes of cracks on your concrete floor other than the common reasons, such as shoddy work. 

1. Rapid drying of the concrete

Drying fast may significantly cause cracking of the concrete floor since the process requires adequate moisture. The hydration process continues for weeks after pouring your concrete flooring. Fortunately, you can solve the problem through proper curing.

2. Excess water in the concrete mix

Many concrete flooring installers use excess water to concrete ratio to make the work easier on the site. However, the excess moisture weakens the strength of the concrete. Moreover, as the concrete dries, it shrinks, thus causing wide cracks evident on some concrete floors. To fix the problem, you should use the minimum allowable water to concrete ratio.

3. Pouring of improper strength concrete on the floor

Concrete is available in different qualities and strengths. Thus, you should ensure you are pouring concrete of standard quality to avoid cracking.

4. Inadequate control joints

The control joints help the concrete to crack through a plane.

5. Pouring concrete on the frozen ground

Ensure the land on which you are laying the floor is suitable according to the soil grade in your area.

Tools & Materials Required in Repair of Concrete Floor

  • Clean masonry sand
  • Portland cement
  • A bonding agent
  • A tape measure or a ruler
  • Smooth trowel
  • Carpenter’s level
  • A shovel
  • Clean water
  • Chipping hammer
  • Wire brush
  • Hard broom
  • Bullnose pointing trowel
  • Steal finishing trowel

Preparation of the Floor Surface

  1. Using a ruler or a tape measure, determine the length and width of the place you want to repair. The area may include depression, ridges, or bumps.
  2. If the problem is on a small floor section, you can get it fixed using floor leveling compounds instead of chipping and removing the concrete out of the spot.
  3. After establishing the size of the surface, you should start the chipping process to remove any high material to create a rough surface. The rough surface is necessary to enable the fresh repair concrete to attach firmly. You can use a chipping hammer for the task.
  4. For convenience, when working on more substantial portions of the floor, you should use a jack chipping hammer or an electric chipping hammer. However, other professionals prefer using surface grinding machines to make work easier.
  5. Using a wire brush, brush the spot and sweep off the chippings. A clean surface will allow the new material to adhere to a sturdy surface. You can also use other methods of cleaning should there be a need.

How to Repair Concrete Floor

The next important step is to mix the materials and fill in the areas chipped out using the following procedure when you are through with surface preparation.

  1. Add 1 part of cement to 2½ parts of masonry sand. Ensure you use clean sand and either grade I or II of cement for a better result.
  2. Mix the dry batch properly before adding water.
  3. Add liquid polymerized or latex bonding agent to the dry mixture. However, some bonding materials may require direct application on the chipped surface. Thus, ensure you have correctly read the manufacturer’s instructions keenly.
  4. Dampen the chipped area with clean freshwater, and be careful not to flood the area. Wetting the surface helps in adhering the new mixture to seal the place.
  5. Moistening the surface will help to solve the problem of rapid concrete drying and ultimately cracking. If you do not wet the area, the dry surface will draw water from your fresh concrete mix.

Filling of Chipped Concrete Surface

When the patches are clean and damp, it’s now time to fill them using a new concrete mix.

  1. Mix the cement and sand well before use on the patches.
  2. Using a bullnose trowel, scoop some of the mortar from your mixing container and place it in the patch.
  3. Work on the mixture on the patch forcefully to ensure no air remaining in the spot.
  4. Smoothen the surface of the patch and leave it relatively higher than the rest of the floor.
  5. Give the patch some time to dry before working on it with a steel finishing trowel.
  6. After some time, when the spot begins to dry, smoothen the surface and allow it to dry for about 2 hours to finish troweling the surface.
  7. Use the carpenter’s level to ensure that your patch is in level.
  8. Splash some water on the source to enhance even drying.
  9. Clean the adjacent surfaces off the concrete by scraping using the edge of your trowel.
  10. If you want to do the work faster, you can use hydraulic cement, which dries and sets within 30 minutes.

How to Fix Cracks in Concrete Floors

If your concrete floor has some cracks that need repair, here is a step-by-step guide.

  1. Using a wire brush, scrub the cracks and sweep off loose debris.
  2. Vacuum the crack and ensure there is no oil or grease stain near the break. In the case of oil or grease, you should clean it thoroughly.
  3. Use a large hammer to undercut the sides of the cracks. Ensure you wear the goggles while performing the task. Undercutting gives the sealant a base to sit firm.
  4. Using a small paintbrush, apply a coat of concrete bonding adhesive on the crack and let it dry.
  5. Mix an appropriate amount of the sand mix according to the manufacturer’s instruction.
  6. Using a smooth trowel, full-fill the crack and smoothen and level the surface.
  7. Allow your patch filler to cure overnight or at least for the period specified by the manufacturer.
  8. Inspect the patch after it dries to find out if there is any additional filling required.

Sealing the Patches

When through with the process above, you should seal the patches to keep the concrete water and stain-resistant. You can use heavy-duty polyurethane to seal the floor. Apply the polyurethane using a brush or a roller to work the coat deep into the rough patch. The main advantage of water-based sealants is that they dry quickly. Moreover, water-based sealants do not have an irritating smell.  Remember to apply a second coat after the first one dries. For the case of high traffic areas, you can coat the crack with at least three layers.

Even though the procedure may seem lengthy, it should take about two to three hours of your time. But you will have saved the floor from future degradation that may widen the gaps. Also, be keen on the procedures not to mess up your work.