Posted by Eric Boullenois - 11 November, 2019
A coating that provides effective protection and waterproofing plays a crucial role in the long-term structural integrity and cost efficiency of any car park. How can a car park be durably and reliably protected? In this article I am going to introduce you to the general approach and the specific properties that must be considered.
Why protecting deck surfaces in parking garages is so important?
Let’s start with the basics. Although a solid concrete slab may appear extremely robust and even indestructible, this impression is not entirely correct. In car parks especially, the concrete is subjected to considerable stress. Mechanical impact as the first point to consider: most modern cars weigh about one ton, and most SUVs are considerably heavier; at any given time, car parks have to deal with dozens or even hundreds of those heavyweights, some of them stationary and others in motion. Parking decks are also subject to the impact of exhaust fumes, lubricants, brake fluids and de-icing salt. In addition, the top-level parking deck is constantly exposed to changing weather conditions – wind, rain, temperature fluctuations, UV radiation, ice and snow.
How do all these factors impact on the concrete?
As a result of these factors, the concrete erodes. Weather-related impacts attack the concrete surface, making the material increasingly porous and leading to cracks. In time, water and de-icing salt will penetrate down to the reinforcement and initiate and accelerate the corrosion process. Combined with the mechanical loads I have already mentioned, all these factors together can significantly compromise the integrity, safety and durability of the structure in the absence of a proper protective, waterproof coating. If an effective protective coating is used, the durability of the structure is improved, making it more sustainable.
What are the main characteristics that such a protective coating must have?
Superior general resilience and crack-bridging properties are keys. The protective coating must be sufficiently robust to withstand the typical stress of a car park. Also, the top deck – usually exposed to the environment – is particularly likely to be subject to cracking over time; in such cases, the protective coating must be capable of bridging those cracks to prevent harmful substances from entering the concrete and causing substantial damage. Other technical requirements, like slip resistance and the need for a certain flexibility in visual design, to outline parking spaces or indicate directions on the floor are also important. While all this sounds very simple, it is often quite demanding in practice.
What are the different layers of the protective coating?
To be effective, coatings used in car parks are composed of two to four individual layers, each of which has different properties for the different tasks they have to perform. The way these different layers are combined ultimately determines the efficiency and the durability of the coating as well as the time required for installation. Details often vary significantly across different projects, and there is no one solution that fits all cases. This is why it is important to ensure that all the requirements are clarified at a very early stage.
|Although it is the thinnest layer in the system, the top coat has a key role and must ensure full protection against: temperature variations, sunlight, attack by deicing salts, and wheel abrasion, while being easy to clean, and ideally allowing a fast return to service. We offer various solutions with different performance features.|
|The role of the wear coat is to protect the membrane from damage due to traffic and also to provide the roughness of the final surface. In combination with the top coat, it ensures slip resistance. For non-crack bridging systems, often applied on the intermediate decks, the wear coat and the primer are combined in one coat. In the case of crack bridging systems, the wear coat ensures the link between the waterproofing membrane and the top coat.|
|The membrane is the watertight, flexible layer that gives its properties to the final system. The other layers must ensure good adhesion of the membrane to the substrate and protect the membrane form mechanical and chemical attack.|
|A primer is the foundation of all systems and ensures adhesion between the protective system and the substrate. We offer various technologies from standard to highly innovative.|
What are the functions of each layer and what challenges do they face?
Depending on the specific application and project requirements, the type and number of layers are selected from a variety of waterproofing membranes, wear coats and top coats which form a complete system together. The layers of a system have different properties. In the case of multi-storey car parks for example, requirements usually vary from level to level. The most important requirements are listed below.
- On the top level, the coating has to be extremely resistant to all kinds of environmental impact and have very good crack-bridging properties. As a result, the typical system for a top deck is made up of 4 layers.
- Intermediate decks are usually enclosed spaces, not directly exposed to weather conditions such as sunlight or rain but need to have good crack-bridging properties to increase the safety and durability of the overall structure. In this case, the system usually consists of 2 or 3 layers.
- On the bottom level, a very important factor to consider is the condition of the substrate under the concrete. The bottom level may require additional waterproofing for protection against groundwater or earth moisture. In this case too, the complete system often consists of 2 or 3 layers.
- Ramps are also highly demanding areas where it is necessary to apply the most resistant systems, usually consisting of 4 layers.
In addition, general requirements to be considered and which apply to the entire structure are abrasion, wear, and skid resistance.