Geobear’s first use of technology on clay soil under a road asset wins nomination

The Chartered Institute of Highways and Transportation (CIHT) has shortlisted global ground engineering contractor Geobear for the CIHT Technology and Innovation award. Geobear’s entry presented its work with Ringway Jacob for Surrey County Council to stabilise deep, shrinkable clay soil beneath the A323 road in the South East of England, using its tried and tested geopolymer injection treatment. The awards will be presented at 8 Northumberland Avenue, Trafalgar Square, London on June 13, 2024.

Surrey County Council faced regular costly and disruptive road resurfacing due to the frequent shrink-swell cycle of clay soils. The apparent alternative was excavation and removal of hundreds of tonnes of clay, and replacement with a gravel sub-base. This too would have been expensive, carbon-intensive and would have caused closure of a main road for several weeks, disrupting the local community and likely forcing a school to shut.

The council approached Geobear to find a third way that would allow it to avoid these high costs and inconvenience. Shrinkable clay soil has a high plasticity index, expanding with water then compacting when dry. This expansion and contraction cycle underground sees the ground’s surface shift and damages overlying infrastructure or buildings.

Geobear, a ground settlement expert, uses an array of injectable geopolymers that expand underground to fill gaps and compress soil, in this case clay. This stabilises the asset long-term, significantly reducing the clay’s shrink-swell capacity and protecting the road surface.

“We developed this solution specifically for Surrey County Council,” explained Richard Holmes, infrastructure director at Geobear UK. “Our engineers assessed the site, specified the key points at which injection holes should be drilled and calculated the quantity of geopolymer needed. We stabilised the clay in situ by injecting our geopolymer at three metres depth. No excavation was needed and the daily lives of people in the area were virtually unaffected: the road reopened 30 minutes after treatment.

“The environmental impact of our projects is a big planning consideration for Geobear too. Not only do we avoid the physical disruption to the local ecosystem of digging up three metres of pavement for miles, our solution produces 62 per cent lower emissions than traditional excavation methods, as verified by Carbon Footprint Ltd.”

Our priority is delivering cost-effective solutions for the travelling public in Surrey that cause as little disruption as possible, which the Geobear solution provides,” said Amanda Richards, assistant director of highways at Surrey County Council and chair of the UK Roads Boards’ Road Condition Management Group.

“We approached Geobear because it ticked many boxes for us: its solution is swift, economical, low carbon, enhances workplace safety and preserves access to surrounding utilities.”

Other local authorities are now considering this innovative approach for similar applications across the UK. To find out how Geobear could solve your road stabilisation issues, read its technical report on lifecycle extension of concrete roads here: https://www.geobear.co.uk/technical-report-lifecycle-extension-of-concrete-roads-using-geopolymer/