Tag Archives: Ground Engineering

Awards, Construction, Construction News, News

Use of geopolymer injection treatment earns shortlist

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/

Case Studies and Partnerships, Construction, Property

Oxford home raised and strengthened with minimal disruption

Mainmark explain how a major property refurbishment was able to take place with the minimum disruption thanks to their resin injection solution

A 1930s end-of-terrace traditional double brick house in Oxford was being converted into apartments. An extended kitchen area was subsiding and had several visible cracks where it joined the main house. The property developer wanted to avoid a removal of the extension and was also seeking peace of mind that the building wouldn’t suffer any further structural damage.

The refurbishment first required ground improvement of the soils beneath the foundations to support the additional load that was to be placed on the structure. The remediation needed to raise, re-level, and re-support the strip foundation within the tolerance of the extension.

There were a number of considerations that needed to be factored in, including the confined space the team had to operate in and limited access to the site due to a neighbouring fence.

A unique approach

A resin injection solution was chosen and applied to the foundation soil, which consisted of sand and gravel. The resin injection application aimed to raise the back portion of the property and maximise ground bearing capacity, which would reduce the risk of further subsidence. The resin solution eliminated the need for demolition or invasive excavation, and minimised disruption, noise and mess for the neighbouring properties.

The process in action

Mainmark’s engineered resin injection solution, Teretek, was applied through a total of seven injection locations at depths ranging from directly below to two metres below the foundations. Teretek is a two-in-one engineered resin injection solution that can increase ground bearing capacity while also re-levelling structures, in a process that is likened to keyhole surgery. On entering the ground, the polymer resin solution mixes together and quickly expands, strengthening the soil and re-levelling buildings quickly and efficiently.

The Mainmark team achieved a maximum lift of 12mm at the lowest corner and work was completed in a single day – the fast completion time allowed the property developer to expedite the refurbishment. The solution also gave the developer peace of mind and allowed the property to be let more quickly, therefore realising a return on investment sooner than anticipated.