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Taxiway and Apron Slab Stabilisation

Challenge

Void formation beneath 58 slabs in a busy airport apron risked future settlement and operational disruption — traditional repairs would have required excavation, downtime, and significant cost.

Solution

Geobear proactively injected geopolymers beneath each slab to fill voids, prevent settlement, and maintain full operations — completing the 12-day programme ahead of schedule in just 11.

11 days

completion — 1 day ahead of schedule

Zero downtime

slabs reopened immediately after treatment

58

Slabs stabilised using 1.5 m injection grid

Background

At a major UK airport, condition surveys using Ground Penetrating Radar (GPR) and core sampling revealed the presence of voids and inconsistent soils beneath slabs in the East Apron and taxiway area.
Although the slabs had not yet experienced significant movement, the airport operator recognised that untreated voids could lead to uneven settlement, steps between slabs, and operational hazards for aircraft taxiing and parking. A decision was taken to act proactively, preventing future disruption by stabilising the slabs in advance.

Challenge

The main challenge was future-proofing the apron area. If left untreated, voids beneath slabs would have allowed differential settlement to develop under aircraft wheel loading, causing lips between slabs and uneven surfaces. This would have created safety hazards, operational delays, and potentially forced slab reconstruction.
The client faced a clear choice:
Do nothing — avoiding upfront costs, but risking future disruption, higher remediation costs, and even penalties from airlines due to operational delays.

Take proactive action — addressing the voids before they led to failures, ensuring operational continuity.

The proactive approach was chosen, requiring a method that could be installed quickly, without excavation or downtime, and with long-term assurance of slab stability.

Proactive, precise, and disruption-free — Geobear safeguarded airport operations by stabilising 58 slabs before problems could arise.

Solutions

Geobear designed and delivered a comprehensive void-filling programme using expansive geopolymer injection:

  • Design approach: A 1.5 m injection grid was used beneath each of the 58 slabs, ensuring uniform coverage and effective void closure.

  • Non-invasive treatment: Injections were designed to fill voids without lifting slabs, maintaining existing geometry and avoiding risks to adjacent joints or drainage.

  • Rapid execution: The works were scheduled over 12 days but completed in just 11, demonstrating efficient planning and delivery.

  • Operational continuity: The resin’s rapid cure allowed slabs to be reopened immediately after treatment, ensuring there was no impact on airfield operations.

The geopolymer resin provided immediate stabilisation, displacing any water present and expanding to occupy voids fully. Its inert, closed-cell structure ensured no risk of leachate or contamination in a sensitive airport environment.

Treatment plan

Airport treatment plan

 

Results

The project delivered measurable benefits:

  • Void closure achieved beneath all 58 slabs, preventing future settlement.
  • Operational risks avoided, ensuring taxiways and apron surfaces remained safe and serviceable.
  • Programme completed early — 11 days vs the planned 12.
  • Cost avoidance — proactive maintenance prevented future costs of slab lifting, reconstruction, and potential airline penalties for delays.
  • Carbon savings — geopolymer injection avoided excavation and concrete replacement, cutting CO₂ emissions compared with conventional repair.

Ready to discuss your project?

Get in touch with our expert team today and discover how Geobear can extend the life of your critical infrastructure assets.

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