Overcoming Structural Concrete Waterproofing Challenges With Cutting-Edge Approaches

Parking structures are built to last but without regular inspections and maintenance, changing environmental conditions will eventually take their toll. Discover how StructureCare identified waterproofing failures and developed a plan to extend the service life of an open-air parking garage.

Problem: Addressing the root cause of deterioration in a parking structure

Concrete is a strong and robust material, but like everything it doesn’t last forever. Water and soluble chemicals are often the main culprits in a concrete structure’s downfall. The root causes of deterioration can be a result of many factors including:

• Moisture and water penetration
• Chemical attacks (such as water-soluble deicing salts and carbonation)
• Freeze and thaw cycles 
• Impact damage (such as snow plow damage) 

When viewed at a distance, concrete appears to be an impenetrable material, but when viewed under magnification you can see that concrete is simply a large, hard sponge that absorbs moisture. This is why the list of problems associated with moisture intrusion in concrete is long and the problems can be catastrophic. 

When our team was called in to inspect and restore an open-air parking garage that was deteriorating, our primary focus was to first address the ill effects of poor water management and then provide the client with innovative, long-lasting solutions. 

Solution: Implementing long-term structural concrete waterproofing and corrosion mitigation solutions  

The two most common types of waterproofing systems are penetrating sealers and film coatings. You can think of penetrating sealers as Gortex, which is both breathable and water resistant, and film coatings as a raincoat, which are vapor barriers. 

Sealers mitigate the condensation process and allow water to evaporate, essentially allowing the concrete to breathe, naturally. When applied they penetrate concrete cracks and voids, to a certain restrictive crack width. They can be hydrophobic silane/siloxane sealers (penetrating water repellent sealers) or hydrophilic and hygroscopic (crystalline technology sealers). 

Whereas coatings are a film layer, applied like paint to cover concrete. Urethanes are typically used in this application and are applied seamlessly to create a continuous impermeable topical membrane, to ensure there is no water intrusion. 

Many people in the industry believe that they need to choose coatings over sealers, however, this choice is not always the right answer. For this particular client, we were able to identify the root issue and determine what materials should be used to maximize durability and the lifespan of the structure. 

Our overall goal was to bring the garage back to “baseline” where repairs and maintenance are much more predictable and more accurately budgeted. To do this, we had to look at the benefits of using a penetrating sealer over a topical coating. These benefits included:

• Allowing the concrete to breathe
• Eliminating condensation
• Promoting evaporation
• Becoming an integral part of the concrete matrix
• Simplifying the inspection process

We also needed to compare the use of crystalline technologies over penetrating sealers. In doing this we found that, in addition to the benefits listed above, crystalline technologies don’t degrade over time, can bridge cracks up to 1/16”, and sustain chloride penetration resistance.

As a result, we recommended the use of crystalline technologies with the additional application of a migrating corrosion inhibitor. The migrating corrosion inhibitor is an amino alcohol that penetrates concrete to adhere to the embedded steel, forming a protective coating. The use of a corrosion inhibitor can significantly reduce the rate of corrosion. 

Migrating corrosion inhibitors offer embedded steel reinforcements protection from corrosion, which is crucial for maintaining the structural integrity of concrete structures. Since it migrates through the concrete, it doesn’t require any kind of treatment to the concrete substrate, making it easy to apply. 

Result: Providing preventive plans to build year-round weather resiliency 

Issues resulting from concrete deterioration don’t often become evident until corrosion of the embedded steel begins to take place. This is contingent on the concrete cover and the penetration rate of the deterioration to reach the reinforcing steel. Typically, we don’t start seeing the deleterious effects until the 20-year mark (give or take 5 years).  

Our experts in structural waterproofing know that most waterproofing systems have a shorter service life than the parking structure itself. So when we were faced with weather-related failures we knew the first thing to do was return the structure to its original baseline condition before offering long-term solutions. 

In the end, we successfully restored the condition of our client’s parking garage and helped them implement preventative maintenance plans that would ensure its structural integrity year-round.