How does a pothole get fixed?

The pothole affects every road in every country in the world – a paving imperfection or damage that causes the road to become uneven and potentially creates craters that can damage suspension or even engine components.

It’s a blight that you’ll primarily find in heavily traversed thoroughfares in the most congested cities in the world, and there’s no real solution other than simply taking the time to fill them in. 

Potholes and other types of road damage are typically caused by overloading, age, or adverse weather conditions. Sometimes, the damage looks like a small dip or bump, and other times, they're piles of asphalt on the sides of the road. These are typically caused by the hundreds of thousands of vehicles plying a street and generally pushing the material in a certain direction. What you know to be asphalt is still technically concrete - unbelievably tiny pebbles held together by asphalt or bitumen - a form of low-grade, oil-based petroleum.

To simplify why asphalt roads get damaged, think of caramel. You make caramel by heating sugar until the crystals in the sugar melt and reform. When you take the caramel off the heat, it solidifies and becomes really hard. But if you reheat a caramel, it melts again. The same thing happens with asphalt, in that it starts as semi-liquid, but when it's poured out and formed, it hardens. But it doesn't stay that way because if the temperatures start spiking, the asphalt starts melting and becomes easy to move around, hence the damage.

How are potholes repaired?

The fix for an asphalt road depends on the kind of damage that's been caused. If the damage isn't structural, meaning it didn't go far down into the ground, the asphalt can be repaired by simply filling in the damage with more bitumen. More severe damage will need that section of asphalt cut out and replaced. 

With the advent of the prefabricated concrete slab, most highways are not as susceptible to potholes as they once were. Concrete, as we know it, is made of sand, water, and a hardening substance known as cement. It gained popularity over asphalt because concrete absorbs water and dissipates it to the ground - that's why you notice that in some places, the ground gets extra muddy around roads but less muddy the further away you get. 

Potholes in concrete typically happen when they're subjected to extreme forces. Concrete is very strong in compression but weak in tension, so typically, they're fitted with metal bars that go inside the concrete to take up said tension. 

What causes damage in concrete is typically overloading, a material imperfection, or a combination of both. Concrete is very strong, but because it's poured in, it is prone to air bubbles which can cause the material to suddenly become brittle, regardless of how it's loaded. Aside from that, concrete has a maximum load capacity, beyond which the aggregate will start to come away. 

Thankfully, it's much cheaper to fix a concrete slab than to repair asphalt, and because of the advent of prefabricated concrete slabs, all they need to do is replace one section with a new one. Sometimes, it's not that easy because of how the concrete is poured and paved, but generally, it's easier than dealing with asphalt. Think concrete reblocking along EDSA.

There’s some new technology, however, that melts down old tires and uses the rubber to create roads – particular use of this technology has been seen at level crossings for trains. Its application is easy, it goes down very smoothly, and it cures quickly, all hallmarks of a pothole repair technique that could prove very effective. Unfortunately, the method is quite expensive, and melting rubber is bad for the environment.

Despite the changes in technology and technique, age-old problems like damage and wear still exist, and while we can’t solve them, we can surely try to solve them. Potholes are no different – we will never be rid of them as long as we drive around on wheels, but coming up with new ways to prevent them in the first place, or fix them as soon as they happen, will minimize the damage they can cause.