Spalling Concrete: What It Is and How to Fix It

If you have ever walked across a driveway, sidewalk, or concrete floor and noticed parts of the surface chipping or flaking away, you have seen spalling concrete. It is a common problem that affects everything from small patios to large reinforced concrete structures like bridges and parking garages. While spalling might look like a simple cosmetic issue, it can quickly grow into a serious concern that affects safety and structural integrity. The good news is that you can understand the common causes of spalling, explore different repair options, and take preventive measures to protect your investment.

What Is Spalling Concrete?

Spalling occurs when a layer of concrete begins to break away from the concrete surface. This process usually starts small, with light flaking or shallow chips, but it can lead to larger patches of damaged concrete or even expose reinforcement bars (also called rebar or steel bars). When left untreated, a spalled area often spreads, making it harder and more expensive to fix.

You’ll often notice spalling on a concrete slab, a concrete floor, or on concrete structures exposed to harsh climates. Driveways, sidewalks, patios, and parking decks are all vulnerable.

Common Causes of Concrete Spalling

So, what leads to this problem in the first place? Here are some of the causes of concrete spalling:

1. Freeze-thaw cycles: In colder climates, water works its way into small cracks or voids in the concrete mix. When temperatures drop, the water freezes and expands, pushing the surrounding concrete apart. Repeated freeze-thaw cycles are one of the most common culprits.

2. De-icing salts and chloride: Spreading de-icing salts in winter may seem harmless, but these chemicals penetrate the substrate and weaken the concrete. Chloride ions also attack steel reinforcement, causing rust and expansion that spalls the concrete cover.

3. Improper curing or poor-quality concrete mix: If new concrete is not cured correctly or the aggregate is poorly chosen, the surface becomes more vulnerable to delaminated or spalled sections. Improper curing leaves the slab weak and prone to damage.

4. Carbonation and chemical reaction: A chemical reaction between carbon dioxide and concrete lowers the alkalinity that protects reinforcement bars, making them more likely to corrode. Similarly, alkali-silica reaction between the aggregate and cement paste can create internal pressure, leading to cracks and spalling.

5. Environmental conditions: Exposure to moisture, heat, and harsh chemicals accelerates deterioration. Even air pollution can speed up carbonation and corrosion.

Why Spalling Concrete Matters

At first, spalling might look like just an eyesore, but it’s more than that. A spalled area can expose steel reinforcement, which expands as it corrodes, damaging the surrounding concrete further. This weakens the entire structure and compromises structural integrity. On flatwork like sidewalks or patios, spalling creates trip hazards. On larger concrete structures, spalling can shorten the life of the building if not addressed quickly.

How to Repair Spalling Concrete

The right repair methods depend on how much damage has occurred. In every case, the goal is to remove the affected area and replace it with durable repair material that bonds with the substrate and protects against future damage.

1. Surface-level Repairs

If spalling is shallow, you can often use resurfacing products or concrete overlays to restore a smooth finish. A thin overlay or patching compound fills in chips and strengthens the top layer of concrete. These products often include polymer additives for better adhesion.

2. Medium Repairs

For deeper spalling that does not expose rebar, the spalled area should be cleaned and prepared, then filled with a strong repair material like a polymer-modified cement or epoxy. Once applied, the repair concrete is smoothed to match the existing surface.

3. Repairs with Exposed Rebar

If reinforcement bars or steel reinforcement are exposed, the repair becomes more involved. The corroded steel bars must be cleaned or replaced, and the surrounding concrete must be cut back to solid material. Then, high-strength patching compounds or specialized mortars are applied. This type of spalling repair is best left to professionals because it often involves structural concerns.

4. Large-Scale Structural Repairs

In parking garages, bridges, or buildings with widespread spalling, larger repair options such as foundation repair, concrete overlays, or full replacement may be necessary. These projects demand professional expertise to ensure long-term performance and safety.

Preventive Measures Against Spalling

Like many issues, prevention is easier and less costly than fixing the damage later. Here are some preventive measures you can take to protect your concrete:

• Apply a high-quality sealer or sealant to reduce water absorption. This helps stop freeze-thaw damage and protects against chloride penetration.

• Consider waterproofing treatments for concrete floors and slabs in high-moisture areas.

• Use sand instead of de-icing salts in winter to prevent chemical deterioration.

• Ensure new concrete is mixed with the right aggregate and cured properly. A well-designed concrete mix creates quality concrete that resists spalling.

• Regularly inspect concrete structures for early signs of spalling. Promptly repair concrete before small issues spread.

• Maintain good drainage around slabs so water does not pool on the concrete surface.

DIY vs. Professional Repairs

Some property owners wonder if they can repair spalling concrete themselves. Small, shallow spalls can sometimes be managed with a DIY patching or resurfacing kit. However, when it comes to exposed rebar, widespread damaged concrete, or structural elements like beams and foundations, calling in experts is essential. Professional crews use industrial-grade repair material, advanced tools, and proven repair methods that ensure the work blends with the surrounding concrete and lasts.

Final Thoughts

Spalling concrete is a warning sign that your concrete structures are under stress. By understanding the common causes like freeze-thaw cycles, de-icing salts, and improper curing, you can act early to repair concrete before it becomes unsafe. With options ranging from simple resurfacing to structural foundation repair, there is always a way to restore both the look and strength of your surfaces.

A-Core Concrete has the tools, knowledge, and experience to handle it. From selecting the right repair material to applying protective sealant and waterproofing, we make sure every job delivers quality concrete results that last.

With 15 locations across 10 states, A-Core provides expert concrete services nationwide with the strength of a local team. If you are seeing signs of spalling on your property, do not wait. Contact A-Core today and let our experts show you the best spalling repair solutions to keep your concrete structures safe, strong, and looking their best.