Asphalt is known for its durability, flexibility, and cost-effectiveness, but even the best-laid surfaces can experience issues over time. Two of the most common and problematic failures are subsidence and deformation. If left unaddressed, these can pose safety risks and lead to more expensive repairs down the line.
At Redbank Plains Surfacing Solutions, we provide professional asphalt and bitumen repairs across Redbank Plains, QLD, and this guide outlines how to correctly identify and repair these issues before they escalate.
Understanding Asphalt Subsidence and Deformation
Before undertaking repairs, it’s essential to understand what’s causing the failure.
What Is Subsidence?
Subsidence refers to a drop in the asphalt surface, often forming a depression or sinkhole. This is typically caused by:
- Poorly compacted sub-base during installation
- Erosion due to water infiltration
- Organic material or debris in the foundation breaking down
- Utility trench failure beneath the surface
What Is Deformation?
Deformation occurs when the surface loses its original shape, often appearing as ruts, bulges or waves. Causes may include:
- High traffic loads, particularly from heavy vehicles
- Soft or unstable sub-grade
- Excessive heat causing asphalt to soften
- Insufficient compaction during installation
Identifying whether you’re dealing with structural subsidence or surface-level deformation is crucial for determining the correct repair method.
Site Inspection and Damage Assessment
Every repair starts with a thorough inspection. The aim is to determine the cause and extent of the damage so the most effective solution can be applied.
Key steps include:
- Measuring surface dips or ridges
- Testing sub-base strength with core samples or ground penetration tools
- Identifying drainage issues or visible cracks
- Checking traffic load history, especially for commercial or industrial areas
Repair Methods for Asphalt Subsidence
Once the cause is identified, repairs for subsidence typically involve restoring the strength and integrity of the base layers.
Full-Depth Removal and Rebuild
- The affected section is cut and removed, down to the sub-base
- The sub-base is compacted or rebuilt with new gravel
- A fresh layer of asphalt is laid and compacted
This method is often necessary for serious subsidence, especially where underlying soil movement or water damage has occurred.
Sub-Base Reinforcement
- In some cases, geo-fabric or stabilising mesh is installed to strengthen the sub-base
- This is followed by asphalt reinstatement to the original grade
Repair Methods for Asphalt Deformation
Surface-level deformation can sometimes be resolved without full-depth excavation, depending on the severity.
Milling and Overlay
- The top layer of deformed asphalt is milled (removed)
- A new layer of hot mix asphalt is laid on top and compacted
- This restores a smooth, even finish and improves load distribution
Infrared Heat Repairs
- For minor distortions, infrared heating softens the surface
- The area is then re-graded and compacted
- A cost-effective option for early intervention
Recompaction and Drainage Fixes
- In cases where poor drainage or heat softening is to blame, grading and compacting the surface again can offer a temporary fix
- Drainage may also be improved to prevent future deformation
Preventative Maintenance
Preventing subsidence and deformation is often more cost-effective than repairing it.
Key maintenance tips include:
- Regular inspections of high-traffic areas
- Prompt sealing of cracks to avoid water ingress
- Ensuring proper drainage design and flow
- Scheduling surface treatments like spray & seal to protect ageing asphalt
Conclusion
Subsidence and deformation in asphalt are signs that deeper issues may be present—whether it’s structural failure below the surface or damage from heavy traffic or poor drainage. Addressing these issues early helps maintain a safer, longer-lasting surface while reducing long-term repair costs.
If you’ve noticed dips, waves or cracks forming in your asphalt surface, Redbank Plains Surfacing Solutions in Redbank Plains, QLD is ready to assess the damage and recommend the most suitable solution. Our team delivers reliable repairs that restore performance and extend the lifespan of your surface.
Call us on: 07 4517 4097
Click here to find out more about Redbank Plains Surfacing Solutions
Click here to complete our contact form and see how we can help with your driveways.
