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Everything You Need to Know About Pothole Repair: FAQs

Are you struggling to find the right pothole repair system for your road maintenance needs? Making the wrong choice can be very costly indeed – in terms of cash, carbon and reputation. The potholes will reform, the budget to fix them must be found again and the original good-news story about splashing out on pothole repair turns into a PR nightmare.

It’s difficult to make the right decision without the right information, so we’ve answered some of the most common questions we get about our pothole solutions and pothole repair more generally.

Why do potholes form?

The source of a pothole is usually a crack or some other small defect. Cracks can form due to repeated loading of the road. It may be that the road is taking more traffic and heavier traffic than it was designed for. In some cases, the bitumen in the road may be old and oxidised, which means it is more brittle and hence more likely to crack.

Utility trench reinstatements are another common source of potholes. The joint between the existing road and the asphalt used to top off the reinstatement widens over time to become a pothole.

Some cracks form in the lower layers of a road and travel up. It could be that the ground beneath a road becomes unstable. This sometimes happens to country roads where intense rainfall causes movement or even causes the ground to wash away.

Cracks widen due to the action of vehicles driving over them. When there is wet weather, tyres can force water into the cracks at pressure, widening them. Freezing spells further increase damage as water seeps into cracks and down into lower layers, expands as it turns into ice and causes more havoc.

Why do potholes come back so quickly?

Often potholes reform quickly because the joint between the pothole repair material and the existing road is a weak point, effectively a tiny crack. Although a pothole solution such as a tack coat may have been applied around the edges of the existing road, there may still be some small areas where the bond between old and new is not 100% repaired. Put simply, some little cracks remain and the whole process starts again.

Sometimes pothole repairs are only supposed to be effective in the short term. For example, on a busy road, the authority responsible for its repair may choose to use a fast-fix method such as cold repair material, so that the danger of vehicle damage or even an accident is minimised until a more permanent pothole repair solution can take place. Cold repair techniques don’t generally last because of weak joints between old and new, even when a cold-spray sealant is used.

What is the traditional way to repair potholes?

A traditional pothole repair would involve cutting out the asphalt around a pothole, using a saw and breaker to cut away damaged material at the edge of the hole, and creating a vertical face for the tack coat to be applied to so that the bond is secure.

Waste material, together with any other loose material, is transported to a processing plant. Hot asphalt, perhaps held in a hot box, is then placed in the hole and compacted.

What about quicker methods?

On country roads, where road closures or restrictions are difficult, spray injection techniques may be a good solution. A high-pressure blower blasts out loose material, a bitumen emulsion is applied to seal cracks, and then the asphalt is sprayed into the hole at pressure, compacting itself in the process.

Mastic asphalts can be used as a quick pothole fix. These consist of bitumen, often modified with a polymer to make them more flexible. They can also be modified with fillers and fine aggregate. Versions which use waste tyre rubber as a form of modifier are also under trial.  

Although there will be some bonding between the existing material around a pothole and the new flowable or sprayable asphalt, there is still the risk of weak points at joints. If the material around the edge of the pothole is not cut out and removed, there could be weak material which again will fail and form new potholes over time.

What about all-in-one machines?

This method applies the same principle as traditional pothole repair methods but uses a Swiss-army-knife approach which puts all the tools required in one piece of plant. This is usually an excavator which has been specially adapted for the task. It has many of the same downsides as the traditional method, for instance, needing waste material to be cut out and removed and running the risk of weaknesses at joints. 

There are health benefits since using attachments on a mechanical arm, rather than being held by a human, removes the risk of hand-arm vibration syndrome (HAVS). They can also be very quick at preparing the pothole for filling. 

However, the carbon benefits are questionable, given this process doesn’t actually fill the holes. A whole new vehicle is required to transport the asphalt and potentially additional pothole repair contractors will be needed to fill the prepared holes. If the excavator has to travel some distance to the site, it may also need an additional vehicle such as a low loader to transport it. On top of that, there are still the same risks of failure and waste material to be accounted for.

What is different about thermal techniques?

The main principle behind thermal techniques is heating up the road in order to make the existing bitumen sticky and flowable so that when new, hot road repair material is added, everything blends together and there is no joint or weak point. 

Some systems simply use a flame, while others use heaters that are positioned over a pothole or defect. The team of road repair specialists here at Thermal Road Repairs went a step further to develop a patented system that monitors the temperature to which the road is heated and then automatically switches off. This equipment is designed to avoid overheating, which can lead to oxidisation of the bitumen and increase the risk of cracking.

Because there is no need to cut a straight edge for the pothole repair, there is no waste material to be taken away and less new material is needed, lowering the use of resources and the carbon footprint of the road repair process. At Thermal Road Repair, we use solar energy and biofuel to top up our heaters, further reducing the carbon footprint of any pothole repair. Again, this method carried no HAVS risk and no noise pollution either.

What about carbon?

When considering the carbon footprint of a pothole repair, it is important to look at the bigger picture – especially as it will be audited further down the line. It isn’t enough to compare the carbon emissions per kg of different repair materials. The relative volumes of new material needed for different repair types, carbon emissions due to vehicle movements for both new material and waste, and the longevity of the repair should all be taken into consideration. 

There is nothing low carbon about a pothole repair that fails and needs to be done again in a few months. The longer the repair lasts, and the fewer return visits that are required, the lower the lifetime carbon footprint.


Thermal Road Repairs is a green technology company which supplies systems to improve the quality, cost and time efficiency of road repairs and paving – at a far lower environmental cost than traditional methods. It invests significantly in R&D, to create new technologies and to continuously improve existing ones.

Thermal Road Repairs: Decarbonising the asphalt repair industry.

High output. Low emission. Zero waste. Permanent solution.

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