Challenge
Weak underlying soils beneath a major A road caused settlement and reduced pavement performance, requiring stabilisation without extended lane closures or disruptive reconstruction.
Solution
Geobear delivered precision geopolymer injection to strengthen sub‑soils, restore support and improve load distribution while maintaining traffic flow.
High traffic volumes maintained
No bulk excavation required
Trafficable shortly after treatment
A section of a major A road was experiencing settlement due to weakened or voided sub‑soils beneath the pavement structure. Reduced support was impacting ride quality and posed a long‑term durability risk.
Given the strategic importance of the route, maintaining traffic flow during remediation was critical.
Traditional dig‑out and reconstruction would have required significant traffic management, prolonged lane closures and increased carbon impact.
The client required a fast, low‑impact solution capable of restoring structural support while minimising disruption to road users.
Alternative Methods Considered
Traditionally, highway repair methods would involve full-depth reconstruction or deep excavation, both of which are time-consuming, costly, and disruptive. Alternative approaches include:
Full-depth reconstruction: Involves completely removing and replacing the road foundation, leading to prolonged road closures and significant material waste.
Pavement structure placement: Would require breaking out sections of the rigid road and pouring new slabs, causing extended downtime and higher carbon emissions.
Cementitious grouting: A potential solution, but it lacks the precision of geopolymer injection and can result in excessive material use with slower curing times.
Why Geobear?
Geobear’s geopolymer injection technology was selected due to its ability to:
Target and fill voids with minimal disruption.
Provide rapid curing, allowing traffic to resume quickly.
Offer a non-invasive alternative to traditional excavation methods.
Extend the lifespan of the existing rigid road structure without the need for full reconstruction.
Offer a low-carbon method to deal with subgrade degradation
The project was divided into two phases, covering approximately 3km of the southbound carriageway. A high-quality Ground-Penetrating Radar (GPR) survey was subcontracted to identify areas of voiding and instability. Based on these findings, Geobear designed and delivered a bespoke treatment. throughout the affected areas. For the affected areas, Geobear drilled through the rigid road into the sub-base at varying levels depending on the depth of the issue. A geopolymer material was then injected as a liquid and expands to fill the voids and strengthen the underlying soils. The expansion fills voids, consolidates the soils and reinstates the contact between the underlying soils and the pavement structure. The works on this site entailed and achieved the following:
Injections were done at 1m grid and reached depths up to 1.5m beneath the rigid road, tailored to the severity of voiding in each section.
Multiple levels of injection were used in some areas to address both surface and deeper instability.
The total length of Geobear injection work for the scheme was 1,470 metres of dual carriageway.
Traffic management was carefully coordinated with the local council to minimise disruption, allowing sections of phase two to be completed within the traffic management setup for phase one, significantly reducing project time.
The road remained open during the day, with overnight closures implemented for efficiency.
The injection purpose was carefully monitored using lasers with high precision to ensure the road surface was not affected.
Testing from pre and post injection revealed that the ground was improved up to 180%.
Testing from pre and post injection revealed that the ground was improved up to 180%.
Performance and load transfer were restored without large‑scale excavation.
The works were delivered efficiently within operational constraints, improving long‑term pavement resilience while minimising disruption and environmental impact.
| Method | Carbon Emissions per Bay (kgCO₂e) | Total Emissions for 150 Bays (kgCO₂e) | Total Emissions for 150 Bays (tonnes CO₂e) |
| Traditional Replacement | 3,490 | 523,500 | 523.5 |
| Geobear Geopolymer Injection | 1,312 | 196,800 | 196.8 |
| Carbon Savings | – | 326,700 | 326.7 |
Total Carbon Reduction: 326.7 tonnes CO₂e (62.43% reduction)
Time Savings Compared to Traditional Replacement
Together with the carbon savings, Geobear’s method brings significant time savings to schemes of this nature. A full-depth replacement would result in a project duration of 5 to 10 months. By contrast, Geobear completed the entire project in under 6 weeks, making the solution at least 4 to 7 times faster than traditional methods. This drastically reduced disruption, allowing the road to remain operational during the day and significantly improving project efficiency.
Get in touch with our expert team today and discover how Geobear can extend the life of your critical infrastructure assets.
