Following a routine condition survey, Highways England identified a section of the A14 at Haughley that had uneven concrete slabs, which presented a potentially unsafe road surface and as such was subject to a larger pavement renewal scheme. The cause of the movement encountered was natural wear and tear but attributable to a combination of poor road surface, increased volume of traffic, water ingress and settlement, which together over time resulted in the slabs dropping.
With the uneven road surface deemed to be unsafe Highways England needed to re-level the surface as fast and as safely as possible, whilst limiting interruption to traffic on what is an extremely busy commuter route.
Infrastructure contractor Osborne was awarded the contract to undertake repairs to this section of road by Highways England, and quickly identified the need for a geo-polymer injection solution to stabilise the soils and lift the slabs prior to the above ground work being undertaken.
The primary alternatives would involve dig out and re-cast meaning a much longer, more disruptive programme of works on the road, which in this instance would not have been either cost effective or necessary for this type of pavement issue. The use of a geopolymer injection scheme was therefore specified from the outset as being the best solution for the task.
Geobear’s geo-polymer solutions were already known to Osborne, who subsequently appointed Geobear as the company to treat the concrete road slabs impacted by the movement.
Many within Osborne had worked with Geobear previously on similar road maintenance issues and were therefore aware of the company’s capability and numerous geo-polymer solutions. The speed, efficiency and non-disruptiveness being particularly valued on this project, as it was important that any disruption to traffic through road closures was kept to an absolute minimum.
The pavement renewal scheme was located on the A14 eastbound and westbound carriageways with the project running from Junction 47A through to Junction 49. The specific areas of treatment were marked on the pavement by the client and highlighted within the road pavement sheets used by Highways England and Jacobs, the tier one contractor.
A total pavement area amounting to 871m2 required Geobear stabilisation and re-levelling treatment on the carriageways. The process in this instance sees 14mm holes drilled through the slabs at 1m centres throughout the affected areas. Geobear’s geo-polymer material is then injected directly beneath the slab. The material upon injection expands within a matter of seconds filling voids and stabilising the ground. Water is displaced from the site as the expansion takes place, ensuring the slabs are completely stabilised upon a firm foundation. Laser monitoring is used to record lift as small as 0.5mm, which provides verification to our technicians that the ground has been stabilised.
Geobear utilised its geo-polymer 1735 to undertake all aspects of the stabilisation and lifting process, which was all completed to the clients required specification
The project was completed during a two-week night shift programme under full road closure to minimise disruption to traffic. Critically, the road remained operational for rush hour and normal daytime use as Geobear’s material has an extremely quick curing period allowing road use within 30 minutes of injection.