Spalling Concrete: Prevention and Repair Tips
Though concrete flooring is extremely durable, it’s not invincible. This porous material is still prone to wear and tear that can cause cracking and spalling — especially if the concrete was not installed properly or maintained well.
When spalling does happen, it’s important to take care of it right away by using the proper repair techniques. Failing to do so can cause more significant damage to the concrete floor and more expensive repairs later on.
In this tech tip guide, we’re talking all about concrete spalling, what it means, how it happens, and how to fix it professionally.
What Is Spalling Concrete and What Causes It?
Concrete floors are rarely, if ever, perfect. Over time, exposure to heavy vehicle traffic, industrial equipment, tracked-in road salts, or extreme temperatures can cause concrete to crack and spall (break off into small pieces).
Unprotected joints and imperfections in concrete often lead to the breakdown of floors. Not only is this kind of concrete damage unsightly, but it also presents a number of liability concerns for property owners, including:
- Trip hazards for workers and visitors
- Physical injury to forklift operators driving over unprotected joints/severe spalling
- Damage to forklifts and equipment
- Product damage from transport over damaged floors
Properly maintained substrate is critical to reduce the costs of product damage, workplace injury, workers' compensation claims, and damage to forklifts and other equipment.
Typical causes of concrete spalling include:
- Freeze-thaw cycles: Because concrete is porous, water can penetrate its surface. When it freezes, it expands and exerts pressure on the concrete. When the ice thaws, it contracts, leading to cracking and spalling.
- Corrosion of reinforcement steel: Exposure to moisture and oxygen can cause the steel rebar within the concrete to corrode. This type of damage can cause internal pressure and create spalling.
- Chemical exposure: Aggressive chemicals can weaken the structure of the concrete over time, breaking down its components and making it susceptible to spalling.
- Poor construction: Inadequate mix proportions, improper curing, or insufficient compaction during construction can result in weak and porous concrete that’s more prone to spalling.
- Abrasion and general wear and tear: High levels of traffic, abrasive materials, or heavy loads can wear down the concrete surface, causing it to spall.
- Moisture: Fluid infiltration through cracks or porous concrete, even if it doesn’t freeze, can weaken its internal structure and ultimately result in spalling.
Without the proper materials and procedures, repairing spalled concrete can fail and lead to even more extensive and costly repairs. Not only is that bad for budgets, but it can also create unnecessary downtime for the business, leading to lost revenue.
Jon-Don highly recommends that all concrete repair work be performed by a properly trained concrete professional.
Spalling Concrete: Joint, Spall, and Crack Repair Tips
Before polishing or installing epoxy coatings, all cracks and spalls must be properly repaired. Failure to do so can lead to the failure of the flooring system.
Before getting started with the repair process, it’s important to properly prep the area. Ahead of laying any kind of filler or repair material, concrete repair professionals should do the following:
- Thoroughly blow out dust and debris from cracks.
- Clean and dry spall areas utilizing a shot blaster or abrasive Nyalox wheel.
- Use a grinder, saw, hammer, or chisel on larger cracks and spalls to widen the area for better filling. As a general best practice, the repair depth should be at least half an inch.
- Create a key way or shelf to allow patching material to adhere properly. A straight edge along the side of the deteriorated area will prevent delamination with future traffic.
Strategies to Prevent Concrete Spalling
It’s always better to take proactive steps to prevent spalling than it is to repair or replace concrete altogether. Of course, even with these preventive measures, concrete may still spall — but these steps should ultimately help to extend the service life of the flooring.
To help mitigate the spalling of concrete, be sure to:
- Apply a concrete densifier to help harden the wear surface: Densifiers react with the free lime in the concrete and create a hardened crystal. This can help reduce deterioration as well as prevent the concrete from dusting.
- Use a penetrating, waterproofing sealer: A waterproofing sealer will help reinforce the concrete flooring, making it more difficult for water to soak through, increasing its resilience.
- Adequately cover rebar during pouring (embedment): Proper construction practices, such as adequately covering rebar, are one of the most effective ways to prevent spalling. High-quality concrete that is poured using construction best practices and is well-maintained can stand the test of time.
- Proper joint placement: The location and distance between joints should be accurate and carefully calculated to help reduce the chance of spalling.
- Use polyurea joint filler: Install a polyurea joint filler with the proper shore hardness to protect the edges of the joint from deterioration. Caulk is only an aesthetic treatment; joint fillers are designed for protection and longevity.
- Proper concrete mixture and mixing techniques: Use a well-balanced mix with the right proportions of cement, aggregates, and water to ensure a strong and durable concrete structure.
- Avoid deicing chemicals and salts: Limit the use of deicing salts on concrete surfaces as these can contribute to corrosion and spalling over time. If deicing salts are required for safety purposes, apply a penetrating chloride blocker to resist potential issues.
Concrete Spalling FAQ, Answered
What Will Happen if My Concrete Is Spalling?
Spalling concrete will chip, crack, and flake, creating erosions on the surface that are not only aesthetically unappealing but a safety hazard, too.
For example, spalling concrete on a floor can cause a tripping hazard, while spalled concrete ceilings can create falling debris that can cause serious injury.
How Serious Is Spalling?
Spalling can be quite serious. If the foundation of a building starts to spall and it is not promptly dealt with, it can compromise the structural integrity of the building. Furthermore, spalling may expose the reinforcing steel within the concrete to environmental elements, leading to corrosion. Corroded reinforcement can weaken the structure and cause additional spalling.
If left too long, the most serious cases of spalling concrete can even contribute to a building collapse.
How Much Does Concrete Resurfacing Cost?
After spalling has been repaired, the concrete will most likely need to be resurfaced to restore its look. Costs vary between repair professionals and contractors but are generally charged per square foot.
On average, concrete resurfacing costs about $3.00-$5.00 per square foot, but can reach as high as $9.00. For decorative overlays, costs range anywhere between $7.00-$20.00 per square foot. A full joint rebuild can range anywhere from $35.00-$45.00 per linear foot.
Concrete Repair Products and Tools
Jon-Don carries a full selection of concrete repair products and equipment that are suitable for a wide range of environments, including indoor, outdoor, deep freeze, or extreme heat. Our concrete fillers can be blended to match the existing concrete surface and give the appearance of a single, neat, and clean finish.
Interested in brushing up on your concrete repair skills? We offer a variety of classes designed to help professionals learn how to polish concrete, repair cracks, spalling, and joints, as well as apply resinous coatings. Contractors, architects, engineers, property owners, and more are all welcome to join.
Looking for one-on-one training and assistance? Our experienced team is ready to help! We can provide in-depth guidance on the following topics and more:
- How to properly fill joints in industrial and stained/polished concrete floors
- Methods for repairing different types of cracks
- How to identify potential problems in new concrete floors
- Which equipment is best to use for repair operations
For more information and upcoming seminars, visit our course page.