What is Pothole?
Pothole refers to the holes in the roadway that can widely vary in shape and sizes. They are usually a circular hole (although could be of any form) signifying water-filled depression over the surface. It immensely depends upon the quality and thickness of the road. The wider the thickness, the lesser will be the possibility of seeing depression on a road surface.
They extensively occur by the expansion and contraction of groundwater. When rainwater or snowmelt is collected and entered into the ground under the pavement, it makes the sub-surface vulnerable.
Why is it called a pothole?
According to Middle English; Pot means ‘a deep hole.’ Hence, the name ‘pothole’ was discovered by American geologists and civil engineers and started referring to these holes as cylindrical holes in river rock, which are formed due to the erosion of the rock over aeons of time.
What causes a pothole?
Potholes are formed when the upper layer of pavement and the sub-base (material lying underneath) cannot support the weight of the traffic. They are widely caused by massive traffic and heavy rainfalls.
What does the Gestation period for a pothole includes?
- The underneath layer is the sub-base of the pavement becomes saturated and soft when the rain droplets or snow moisture enters the cracks in the pavement, and the moisture cannot adequately drain away from the sub-base.
- The moisture trapped inside the sub-base retains, causing the cracks to expand. On top of it, the traffic makes this situation worse by cracking it further.
- A void is left under the pavement, even with a slight rise in the temperature. The void allows the water to retain, which overall makes the void massive.
- Traffic passing over the road surface when the void is enlarged induce the surface to break and collapse into the void below, leading to a pothole.
How are potholes repaired?
1. Cold-Patch (Throw and Roll)
It is one of the repairing methods used by many road contractors. However, the failure rate of this method is high. The contractors place asphaltic patch material inside the pothole and drive over a heavy vehicle, a truck, roller, tractor, JVC, or bulldozer. The repair is quick but temporary. You might feel it is a simple method. However, it is quite an expensive methods as compared to the other ones.
2. Hot-Patch Semi-permanent
This method is better than the throw and roll but not fully permanent. The foremost thing to do is remove the water and the debris from the pothole, and then the corners of the pothole are trimmed, making them uniform. This allows the asphaltic patch material to pack inside the pothole evenly. Once it has taken its place, a vibratory roller or vibratory plate is used to compress the patch.
3. Spray-Injection pothole repair
This method is quite similar to the hot patch semi-permanent one. However, spray injection is only possible with the help of specialized equipment. The water and the debris are blown out from the hole, and asphalt material and aggregate are placed into it. Before you put the material into the hole, a tack coat of binder is sprayed on all sides of the hole. Then, the layer of aggregate is used to cover the patched area. The best thing about this method is that it does not require you to compact the hole.
4. Edge-seal pothole repair
The edge-seal repair method can only be practised only if the throw and roll method is used to fill up holes. Once you are done with that method, a ribbon of asphalt tack material is placed along the edge of the patch. The only thing you need to ensure is that it should overlap the pavement.
Can you prevent the formation of potholes?
The best way to prevent potholes is pavement preservation as soon as the cracks start to appear on the pavement surface; sealing those cracks and using specific preservation treatments before severe distress appears the effective way of preventing potholes.
The preservation treatments include providing firm support, patching, crack sealing procedures (fog seal, chip seal, slurry seal, or sand seal) and removing superfluous material.