A12 Marshland Road Scheme | Great Yarmouth Norfolk

Leca® Lightweight Expanded Clay Aggregate has been used to construct an extension to a coastal road scheme where its lightweight properties reduced the time required for settlement by at least 75%.



A12 Marshland Road Scheme | Great Yarmouth Norfolk Motorway England

Leca® Lightweight Expanded Clay Aggregate has been used to construct an extension to a coastal road scheme where its lightweight properties reduced the time required for settlement by at least 75%.

A roundabout was extended from one lane to two to accommodate traffic using a new Tesco supermarket on the outskirts of Great Yarmouth, Norfolk. The challenge for engineers was that the coastal location is low lying, its condition is naturally marshy and the water table rises and falls with the tides. The roundabout sub-base and pavement were extended onto the existing verge and a new embankment was built using Leca® Lightweight Expanded Clay Aggregate. The contractor was J.Breheny Civil Engineering, working on the adopted roads, on behalf of R G Carters (Builders) Limited and Tesco Stores Limited.

Civil engineering designer, Boreham Consulting Engineers Limited, had specified the use of Leca® Lightweight Expanded Clay Aggregate to minimise differential settlement.

Breheny cutaway the existing embankment at a right angle to the line of the new outside edge of the carriageway. Services were then installed including 14’ deep wick drains and a drainage blanket. The Leca® Lightweight Expanded Clay Aggregate, in conjunction with the wick drains, accelerated settlement to completion within six months, compared to an expected two to three years using conventional fill and piling.

The Leca® Lightweight Expanded Clay Aggregate was tipped over a geotextile membrane and tracked into place using a mini excavator to minimise any surface movement. The geotextile was then rolled over the Leca® Lightweight Expanded Clay Aggregate, creating a ‘sausage’, preventing migration of the material. This was then soiled and seeded. A total of 753m3 of Leca® Lightweight Expanded Clay Aggregate was used on the Gapton Hall roundabout.