Concrete is pretty tough material all by itself. That's why it's one of the most ubiquitous construction materials and synonymous with strength in everyday vernacular* .
But despite its many great features, concrete and other types of masonry have one weakness: water. So how can we protect structures that use A LOT of concrete (like a parking garage) from this scourge? With a traffic coating of course!
Properly selected and applied traffic membrane systems can protect concrete from deterioration caused by moisture, environmental and other service conditions. But the word "system" conjures up headaches for most architects and engineers. "Systems" almost always mean more than one component and usually complicated sequencing of installation. So let's peel back the layers of a quality waterproofing system to make it a little more simple.
Most traffic coatings are comprised of three to four layers, each serving a different function. Once vapor testing and surface prep is compete, the first layer is a primer. The key to the longevity of a traffic coating system is its bond to a sound concrete substrate. A primer not only ensures that you have a good bond, but can also help mitigate moisture drive issues if they are present.
Some companies try to sell their systems by skipping this primer step and saying that a primer isn't needed. To paraphrase Chris Rock:
"You can do it if you want to but that doesn't mean it's to be done! You can drive a car with your feet if you want to. That doesn't make it a good (expletive)-ing idea!"
The second layer is the urethane membrane that is essentially the workhorse of the entire system. This material is the layer that really keeps the water out. Urethane membranes have the ability to move with your concrete and span certain types of cracks as well. However, urethanes are soft and aren't tough enough to withstand the wear of car tires or heavy pedestrian foot traffic.
The third layer is an "intermediate coat" that is broadcasted with some kind of fine aggregate. This coat is sometimes called a "lock coat" because it is the material that "locks" the fine aggregate in place, which provides the durability and skid resistance.
The final layer is an topcoat. This last step protects the aggregate layer and provides a tenacious, UV stable color that can last years with proper maintenance.
Too Long...Didn't Read...
Typical Traffic Coating Layers:
1) Primer - Bonds the system to the concrete
2) Membrane - Provides the true waterproofing performance
3) Intermediate - Protects membrane and locks in the aggregate
4) Topcoat - Increases durability and provides aesthetic appearance.
If you want to learn even more there's a great tech guideline from the International Concrete Repair Institute that goes into further detail on the many types of traffic coating systems.
*That's right...I used "ubiquitous", "synonymous" and "vernacular" in the same sentence. Thank you word of the day calendar!)