Spalling vs. Cracking: What’s the Difference?

Spalling vs. Cracking: What’s the Difference?

Spalling and cracking may seem the same at a glance, but there are significant differences that require unique approaches to repair.

Key Takeaways:

• Spalling is a common concrete problem where part of the surface peels, breaks, or chips away
• It is caused by chemical reactions inside the concrete, leading to the formation of corrosion products that increase the internal pressure, leading to cracks
• Concrete can also develop cracks due to exposure to extreme temperatures or poor design, placement, or finishing
• Several preventive measures and repair options are available to help reduce the risk of concrete spalling and cracking
• High-quality materials and properly proportioned concrete mixes are essential for strong, durable concrete surfaces

Concrete is a great way to add strength and stability to any construction project. It’s energy-efficient, highly cost-effective, and provides superior fire resistance compared to other building materials. However, like all materials, concrete is subject to wear and tear over time. Two of the most common problems concrete surfaces encounter are spalling and cracking. 

These two types of damage can make concrete polishing and coating challenging and cause significant damage to the overall structure. Let’s take a closer look at spalling and cracking so you can better understand how to protect your investment.

What is spalling?

Spalling concrete, also known as scaling, is the peeling, breaking, or chipping away of the surface layer. It’s the result of a weak surface caused by several chemical reactions inside the concrete that lead to the formation of high-volume foreign corrosion products. 

These products take up space and increase the internal pressure, causing breaks to form and release the pressure outside. These breaks pave the way for the atmosphere to further react with the concrete, exacerbating the spalling.

Spalling is often the result of exposure to freeze-thaw cycles or deicing salts. When water seeps into the concrete it expands as it freezes, putting immense pressure on the surrounding material. This can cause the surface to flake away or pop off in chunks. Other causes of spalling include:

• Improper concrete curing: Concrete curing helps improve the durability and strength of the material. Inadequate curing can cause weak concrete that is more vulnerable to weathering, chemicals, and other environmental factors.
• Poor quality concrete: The strength and stability of concrete depend on the quality of the ingredients used. Using subpar materials can lead to a lower-quality final product that is more susceptible to weathering and damage.
• Poor finishing techniques: Once the concrete is poured, it needs to be correctly finished. If these steps aren’t carried out correctly, it can lead to a weak surface that is more prone to spalling.

Repairing spalling concrete

Immediate repair is essential to prevent further damage and deterioration. There are three main methods for repairing spalling concrete depending on the severity of the damage:

• Patch spalling: A concrete patch can be used for small areas of spalling. This method involves chipping away the damaged concrete and replacing it with new material. The patch should be made from a high-quality concrete mix that matches the original material. Clean the area thoroughly before applying the patch to ensure good adhesion. Apply anticorrosive primer to the reinforcements to protect them from further damage. Cure the patch according to the manufacturer’s instructions.
• Overlay repair: An overlay is a thin layer of material applied over the existing concrete. It’s ideal for repairing more extensive areas of spalling, cracks, and surface defects. The new layer should be made from a high-quality concrete mix that matches the original material. Once it’s applied, trowel the surface to create a smooth, even finish. Cure the overlay properly to ensure long-lasting results.
• Replacement: In cases of severe spalling, replacement may be the only option. This involves removing the entire damaged section and pouring new concrete in its place. Partnering with a qualified contractor is essential to ensure that the replacement concrete is properly mixed, poured, and cured.

How to prevent concrete spalling

Prevention is always the best cure. There are several steps you can take to prevent spalling concrete:

• Use high-quality materials: This includes using quality concrete, reinforcement, and aggregates. Choosing the right materials is essential to ensuring a long-lasting, durable product.
• Cure concrete properly: Proper curing is essential to the strength and durability of concrete. Be sure to cure concrete according to the manufacturer’s instructions.
• Apply a sealer: A sealer helps protect concrete from weathering, chemicals, and other environmental factors. Be sure to choose a sealer that is compatible with the concrete mix.
• Use proper finishing techniques: Follow the appropriate finishing techniques once the concrete is poured to help ensure a strong, durable surface.

What is cracking?

Concrete cracking is the development of fissures or hairline cracks on the surface of the concrete. These cracks can result from drying shrinkage, thermal expansion and contraction, or external forces such as traffic or vibration. Concrete cracks can lead to a loss of strength and stability and can allow water and other materials to enter, leading to further deterioration. Proper design, placement, and finishing of concrete can help minimize cracking.

Types of cracks

There are several types of cracks that can occur in concrete, depending on the cause:

• Expansion of concrete cracks: Concrete expands when exposed to heat or moisture. Any variation in temperature or humidity can cause expansion cracks.
• Shrinkage concrete cracks: As concrete dries, it shrinks. This can cause cracks to form as the concrete tries to pull away from the edges.
• Plastic concrete cracks: Plastic concrete is still in the early stages of drying and hardening. These cracks usually occur within 24 hours after the concrete is poured. As the water evaporates, it leaves huge gaps between the aggregates.
• Heaving concrete cracks: Exposure to freezing temperatures can cause concrete to heave or rise up. This can put stress on the concrete, leading to cracks. As the temperature warms, the concrete will return to its original position.

How to repair cracks

Cracks can compromise the strength and stability of concrete. Therefore, it’s important to repair them as soon as they’re discovered. There are several methods for fixing cracks, depending on the size and severity of the damage:

• Caulking: Caulking is a common method for repairing small cracks. This involves filling the crack with a sealant, such as silicone or epoxy.
• Sawing and sealing: Best suited for medium to large cracks, this method involves cutting a V-shaped groove into the crack and then filling it with an epoxy or urethane sealant.
• Stitching: Stitching is a method of repairing cracks with steel cables or rebar. This involves drilling holes on either side of the crack and inserting the cables or rebar, which are then tied together to pull the crack closed.

How to prevent concrete cracks

There are several ways to help prevent concrete cracks:

• Use proper concrete mix: A properly proportioned concrete mix is essential to a strong, durable surface. A low-water-to-cement ratio is the key to a strong mixture. Prepare the surface properly before applying the concrete.
• Install control joints: Control joints are intentional cracks that help control unintentional cracking. By providing a weak point, control joints help prevent random cracking. Place them at regular intervals and seal them with a flexible sealant.
• Cure properly: Curing helps prevent cracking by keeping the concrete moist and allowing it to cure slowly. Follow the manufacturer’s instructions for curing time and methods.

Protect your concrete design project with Concreate

Concrete spalling and cracking can significantly compromise the strength, stability, and durability of your concrete design project. But with proper design, placement, and finishing, you can help minimize these risks. 

At Concreate, we love what we do, and we do it well. We are committed to providing our customers with the best quality products and services to help them create beautiful, long-lasting concrete designs. Our team of experts can help repair your concrete economically and quickly. 

Our finished concrete products are aesthetically pleasing, stain-resistant, easy to maintain, and slip-resistant due to our unrivaled expertise in concrete polishing, surfacing, and finishing. If you’re looking for a durable, low-maintenance concrete solution, look no further than Concreate. Contact us today for quality and affordable concrete repair and polishing services.