During routine inspection work Highways England identified that 39 concrete bays required stabilising and releveling treatment using a Geobear geopolymer injection solution. The M54 J3-J2 eastbound scheme was completed in July 2020 and involved pavement maintenance works to address historical concrete carriageway defects. The concrete bay stabilisation work was completed with minimal pre-scheduled closures.
Highways England employed Area 9 maintenance contractor, as Principal Contractor, who subcontracted with a traffic management specialist, who in turn subcontracted the slab stabilising activities to geopolymer injection specialist, Geobear.
Geobear’s positive approach to collaborative working involved a number of specialist contractors working together meant that an efficient and cost-effective project for all participants.
We were able to minimise the impact of traffic disruption to road users by completing our works in the allocated programme duration of 72 hours. Our complete process was delivered under full highway closes over two weekends of nighttime working.
Using Geobear’s geopolymer injection process, all 39 bays were stabilised and relevelled in 5 shifts by 2 injection teams working consecutive shifts. This system of work ensured maximum use of the road closure. Effective handovers by our supervisors ensured key project information such as completed bays and marked bays to be treated next along with lessons learned such as mark post locations were quickly passed to the incoming team.
Geobear’s geopolymer has fast curing times and this means that programme surety and confidence was generated for the highway asset owner and gave reassurance that the highway was re-opened to users at 10:00 am on Sunday morning. Our approach meant that affected communities and road users experienced minimum disruption during the works.
Geobear also carried out in-situ testing on pre-treated and post-treated bays to provide measurements on the improved load spreading capabilities of the subbase and sub-grade. This approach demonstrated that the in situ load-carrying capacity of the subbase layer was improved from a Class 1 to a Class 2 equivalent foundation. A long term solution has been provided giving Highways England confidence that the asset life has been extended.
Safety & Collaboration
On the M54 project, Geobear treated 5 times more bays per shift, when compared to alternative techniques such as dig out and replace. The Geobear approach significantly reduced construction plant movements such as ‘muck away’ and incoming concrete wagons as these resources are not required for the geopolymer process and therefore minimises the hazards associated with plant movements when working at night.
During the ECI stage, we developed a strong working relationship with our fellow specialist sub-contractors who provided us with task lighting and injection drill holes reinstatements. This approach enabled the geopolymer injection teams to efficiently complete their bay stabilising activities moving on to the next slab in the knowledge that colleagues would complete the reinstatement using a client-approved compound.
Geobear brought programme efficiencies using 52 of the 72 hours allocated to slab stabilisation on this project and generated cost savings created by utilising reduced labour and plant resource and the associated reduced number of mobilisation activities. This method of working also ensured that we were able to proactively mitigate time-consuming bottlenecks with other contractors who used much bigger and heavier plant.