ESP are currently involved with earthworks on a residential site in Wiltshire using Gault Clay – a heavy (high plasticity) clay – where a noise attenuation bund is being constructed between a residential development and major highway. The moisture content has a significant influence on the compaction characteristics and shear strength of the clay, and hence the stability of the constructed bund. To improve these characteristics the moisture content is being reduced by rotavating lime into the clay.
The clay is laid down using a blade (bulldozer) as in normal earthworks, and the specialist subcontractor then passes over it with a rotavator, churning the clay up, but also adding lime as they go. In this process, the clay changes from large clods to a crumb type texture, with lime incorporated. The lime triggers a chemical reaction which reduces moisture content of the clay. The crumbed limed clay is then compacted in the usual way.
Check out the video below to watch this in action!