The 1.5km A50 Growth Corridor road development project to the West of Uttoxeter provides improved access to new housing and employment sites and is part of a multi-million pound investment by the Government under the control of Staffordshire County Council. It also improves access to the existing and new JCB factories to the north of the A50. The scheme delivered a grade separated junction where embankments have been raised to an overbridge on the A50.
Site investigation in the area where the embankments were raised showed patches of soft made ground susceptible to differential settlement. The specification gave the option for the contractor to use a locally supplied, lightweight Pulverised Fly Ash (PFA) to reduce overall settlement. The challenge was to reduce the differential settlement and to give stability to the 1 in 2 rising side slopes which curved around a SuDS balancing pond. The nature of PFA is that it is fine grained and often of a high acidity. Any material used should be able to withstand any corrosive effects of the PFA, bond with the PFA and be easy to cut to shape around the relatively tight curve of the embankment. A low-creep, high-stiffness material would be preferred as any movement in the PFA is detrimental to the compaction process. Since Highways England manages the A50 trunk road, BBA certification was required.
ABG Enkagrid Pro geogrid was selected as a highly stable, BBA certified low-creep geogrid. The stiffer geogrid lays flat and presents a high friction surface to the finely graded PFA, enabling good load spreading. The geogrid is cut to shape easily using a disc cutter on site to suit the curved embankment. The rolls of Enkagrid Pro geogrid are placed using a spreader beam and then overfilled allowing compaction equipment to pass over the edge of the grid to:
(1) Ensure a fully compacted surface
(2) Trim the face back to line
(3) Finally seal with a clay fill and add a layer of topsoil
The ABG Service
ABG supplied Tarmac with all the relevant certificates and technical data sheets to satisfy the requirements of the consultant to ‘BS8006 – Code of Practice for Strengthened/Reinforced Soils and Other Fills’, as well as certification required by Highways England via BBA.
Contact ABG today to discuss your embankment reinforcement project specific requirements and discover how ABG’s past experience and innovative products can help.
This scheme is an example of implementing an idea from the Highways England “Managing Down Costs” Toolkit.