Home
My Wrekin
William Davis Homes, Oak Grange Development

Value Engineered Road for Oak Grange housing development

  • William Davis Homes

  • Oak Grange, Derby

  • 40m adoptable road

  • Geotextile & biaxial Geogrid

The Wrekin Products geosynthetics team value-engineered a fit-for-purpose adoptable road for a new Derby housing development, working with the city council, William Davis Homes and S&L Groundworks.

The team created an adoptable road solution for new housing development Oak Grange. Derby City Council’s overseeing engineer had previously highlighted various issues surrounding the creation of a permanent adoptable road that needed to be resolved before the adoption could progress.

The Wrekin team visited the site and identified that, before using a geogrid solution to significantly reduce the road foundation thickness, a performance trial was needed to prove efficacy for implementation. This was due to the very weak subgrade and the potential for differential movement.

First, Wrekin cleared a 20-metre long on-line area down to the sub-formation, with an additional ten metres at either end to allow for access and egress. An initial layer of MultiTrack MT1000 geotextile provided separation of fines and filtration of water flow, which could have otherwise weakened the foundation over time.

The geotextile layer offers efficient separation and filtration, and when partnered with subsequent geogrid layers, it ensures strong reinforcement by enhancing the stability of the 6F5 aggregate used for capping materials.

MultiTrack with sub-base and E'Grid

A further granular sub-base layer was installed and tested, producing results between 70% and 100%, far exceeding the requirement of the pavement foundation. This confirmed that the geogrid solution and application was suitable for adoption to overcome the identified problems.

Shahid Raza

Wrekin Products Ltd.

Oak Grange housing development by William Davis homes

The first layer of Wrekin’s E’GRID™ rigid biaxial geogrid was rolled out over the top of the MT1000. 250mm of 6F5 aggregate was placed and then compacted by a roller, followed by another layer of geogrid and a further 250mm of 6F5.

The substantial half-metre reduction in foundation thickness over a conventional founding section reduced the total excavation and export of earthworks, therefore reducing the overall import and compaction of aggregates required.

After the construction of the founding layers, plate bearing tests confirmed the in-situ performance at the formation level, on top of geogrid reinforced capping layers. Five plate bearing tests were taken on the inner 20 metres of the performance trial area, with the highest result being 47% and the lowest result being 18.7%. The performance trial area therefore exceeded the preliminary requirement of 15% at the formation level.

A further granular sub-base layer was installed and tested, producing results between 70% and 100%, far exceeding the requirement of the pavement foundation. This confirmed that the geogrid solution and application were suitable for adoption to overcome the identified problems.

Altogether, this project demonstrates how value engineering solutions such as geogrids can be used to solve general and site-specific issues for the housing sector, while simultaneously saving contractors time and money.

Gallery

Related case studies

Related case study

Providing the answer to access issues at Scottish Wind Farm

Wrekin were selected over two other civils manufacturers to provide materials to support the creation of an economical access road to aid the construction of a new wind farm.

Greencat Contracting
Greencat Contracting
Read more
Related case study

Longhill burn Wind Farm

A new multi-million-pound wind farm is currently being constructed in West Lothian and, upon completion in 2022, it will be one of the largest onshore farms in the UK. Work at Longhill Burn wind farm in West Calder started in April 2021, with operations and management delivered by leading wind farm business, Energiekontor UK.  

A E Yates
A E Yates
Read more