Why Does Asphalt Crack?

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This month on the Sunrise Asphalt blog we are focusing on road repairs! The who, what, when, where and why of asphalt degradation and repair. First the problem, the question. ‘Why does asphalt crack?’ It is a common query, after all it seems like such a durable surface, but potholes are an all too common agitating road hazard and so people wonder what causes that literal dip in the road. So, first let us answer just why asphalt cracks.

Why Does Asphalt Crack?

Asphalt cracking is one of the most common kinds of damage in asphalt surfaces. While asphalt is incredibly durable it can take damage. Extreme cases are called fatigue cracking or crocodile/alligator cracking. These cracks form from the base up to the surface, spider-webbing across the surface and looking like the hides of those previously mentioned reptilian beasts. The most common cause of fatigue cracking in asphalt is traffic loading, but that is only partially the problem. What allows the overload to damage the asphalt is often environmental influences that create a situation ripe for disaster.

We have discussed the process of building roads, the way aggregate bases and layers are levelled and applied to ensure a road is paved correctly. Any miscalculations or errors in this process will create an environment for failure. For instance, the base or subgrade can be degraded from inadequate drainage for instance. A particularly heavy thaw in the spring can also weaken a base. When the base (and subsequent layers) are weakened then the asphalt sitting on the top loses its support and heavy traffic loads will break those weakened foundations.

Similarly, another way asphalt may be weakened is through raveling. Raveling, or stripping, is what happens when asphalt and aggregate are not properly adhered together. The adhesion breaks and the aggregate begins to shift. This shifting decreases the thickness of the pavement which leads to… you guessed it, cracked asphalt! Raveling can lead to fatigue cracks occurring much faster.

These are the main causes of cracking in asphalts. Sure, much more catastrophic events can lead to them, such as earthquakes or significantly explosive accidents, but when it comes to road repair we see much more crocodile cracking then landslides or sinkholes. The easiest way to deal with cracking is to prevent it from ever occurring, as you may have picked out from our descriptions of how it happens, it is often because of improper construction making the surface weaker in the long run.

Unfortunately, damage can’t always be avoided even with the best construction available. When that happens, you will be wondering how to fix the cracks. Well, come back next time where we will go over the various means of asphalt crack repair. And if you have repairs that need to happen now, contact us today and we can make your path clear.