Airport ground improvement solutions

Key Airfield Failure Mechanisms

1. Subgrade weakening and settlement

The performance of all pavements is fundamentally governed by the strength and stability of the underlying subgrade and its interaction with groundwater. If the subgrade is poorly compacted, weak, or becomes saturated, it can consolidate or erode over time. This leads to localised depressions, poor load distribution, and cracking in the layers above

Common causes include:

• Inadequate compaction during construction
  
  
• Seasonal groundwater fluctuations and poor drainage
  
  
• Leaching of fines through soakaways or leaking utilities
  
  
• Cyclic loading that gradually densifies loose subgrade soils
  
  

These issues are particularly pronounced around manholes, utilities, and service trenches, where compaction is difficult and soil washout can occur.

2. Water ingress and drainage deficiencies

Water is one of the most damaging agents in pavement performance. Trapped water reduces the bearing capacity of soils, promotes pumping, and leads to freeze–thaw heave in colder climates. Poor surface grading or localised depressions allow water to pond, accelerating deterioration of both flexible and rigid pavement types. Over time, moisture infiltration through cracks or poorly sealed joints causes loss of fines, void formation, and eventual surface deformation.

3. Repetitive and concentrated dynamic loading

Pavements are subjected to millions of load cycles over their life. Heavy vehicles and aircraft impart high dynamic loads that cause fatigue failure in asphalt layers and differential settlement in the underlying structure. Concentrated wheel paths, such as runway touchdown zones, taxiway turns, or motorway slow lanes, are particularly susceptible to rutting and depressions as the material compresses under repeated stress.

4. Material aging and surface degradation

Bituminous binders harden over time due to oxidation, making the surface brittle and prone to raveling, cracking, and aggregate loss. Bleeding, blistering, or oil spillage can also degrade surface texture and skid resistance. In rigid pavements, joint deterioration and pumping lead to slab faulting and loss of support. These mechanisms progressively reduce ride quality, friction, and structural performance.

5. Construction defects and geometric errors

Even small deviations in laying geometry or joint treatment can create long-term weak spots. Poor longitudinal joint construction in asphalt, insufficient saw cuts in concrete slabs, or misaligned layers can initiate cracks and separations. Depressions caused by laying errors or localised settlement can accumulate water, increasing hydroplaning risk and accelerating further damage.

6. Environmental and operational factors

Environmental conditions such as temperature cycling, freeze–thaw action, and thermal expansion in concrete contribute to distress mechanisms like block cracking, heave, and blowups. Operational factors—such as jet blast erosion, fuel spills, and heavy braking or turning loads—can further accelerate deterioration, particularly on airfield aprons and taxiways.

Airfield pavements are subject to unique stresses:

• Runways must resist dynamic landing loads, tyre bursts, braking forces, and fuel/oil damage.
  
  
• Taxiways carry heavy turning aircraft at slow speeds, where rutting and slab settlement can compromise safety.
  
  
• Aprons and stands endure high static loads, fuel spills, and constant vehicle traffic, demanding durable, non-disruptive repairs.