Groundwork specialist pioneers new technique to cut costs and reduce waste sent to landfill

Groundwork specialist Stent is pioneering a technique to make “concrete” from excavated soil and clay. The technique is designed to cut costs and reduce the amount of waste sent to landfill.

The firm is planning to turn the material into a liquid that can be used for backfilling in foundation trenches.

According to Viv Troughton, Stent’s technical director, many clays and silts are sent to landfill because they are considered unusable. However, with the rising cost of disposal and the greater focus on sustainability, there is a growing need to find a way of using them.

The technique, which is called AggReFlo, pre-treats excavated material with lime to reduce its plasticity before it is mixed with cement to give it strength. The key step is the addition of a compound that enables the mix to retain water, which allows it to flow. This means large volumes can be installed rapidly without the need for compaction.

Site waste
The technique aims to reduce the amount of waste going to landfill

Troughton said. “As well as the benefit of re-use, there are health and safety advantages as you don’t need workers in the excavation to compact the fill.”

Stent is working in a joint venture with German company RSS.

The AggReFlo system is currently undergoing UK compliance tests.