Britpave: The British In-Situ Concrete Paving Association

Aggregate shortages eased by soil stabilisation

Increased use of soil stabilisation and solidification would help ease the problems of declining aggregate reserves believes Al McDermid, Chair of the Britpave Soil Stabilisation Task Group.

The Mineral Products Association in its latest Annual Mineral Planning Survey, has raised the issue of declining aggregate reserves and called upon the Government and planning authorities to speed up the planning system for aggregate reserves. Failure to do so means maintaining a steady and adequate supply will become increasingly difficult. Sand and gravel is being severely under-replenished as reserves are being used twice as fast as new capacity is being permitted. Despite a few large planning permissions, crushed rock is also suffering from general under-replenishment.

Commenting on the survey, McDermid said: “When it comes to soil improvement for transport infrastructure projects or remediation of brownfield land for building, soil stabilisation and solidification is a sustainable solution. Dealing with the soil issues on site greatly reduces the need to import virgin aggregates. Further environmental benefits include reducing the lorry movements and landfill taxes associated with the outmoded dig-and-dump approach.”

Soil stabilisation involves using cementitious binding materials such as lime, cement, fly ash or ground granulated blast furnace slag (GGBS) to improve the physical properties of the soil to provide a strong engineered construction material. With brownfield and contaminated land, the stabilisation/solidification of the soils either treats the contaminants on site to produce a soil that is either less or non-toxic, or has no ability to leach them. The strengthened and improved engineering properties of the soil means it can then be used for road, pavement and foundation construction.

“The slow planning process for quarrying permissions plus the fact that aggregates are a finite resource underline the environmental benefits of on-site treatment of problem soils”, said McDermid.