Lime modification of soils has been discovered to also have significant capabilities to treat contaminated soils and deliver environmental benefits. Lhoist has developed Neutralac® products for this market.

Lime reacts with water and clays in the soils to effect physical and chemical changes that improve the characteristics of the soils for handling and engineering purposes. The chemical changes can also combine a wide range of contaminants in with the modified soil reducing mobility of the contaminants. The benefits that the drying action of lime on soils can deliver on contaminated sites include the improvement of handling characteristics for the soils as well as increasing site efficiency and benefiting working conditions.

The increasingly unacceptable practice of ‘dig and dump’ for contaminated soils can be largely avoided altogether or significantly reduced for many, including some of the most extreme of, contamination situations. Lime treatment of contaminated soils can deliver significant environmental and cost advantages by avoiding thousands of lorry movements and the difficulties of high cost and legislation compliance in disposal of contaminated soils.

Treated contamination sites are capable of being put to economic re-use for industrial, commercial and residential development. Laboratory analysis, experienced assessment and binder design, as well as field trials and compliance testing are always required for dealing with contaminated soils. Where soils conditions and contaminants require, lime is used in combination with other binders and additives to deliver even more significant modification actions, both physical and chemical.

Lime modification of contaminated soils usually requires to be carried out at significant depths and this is achieved through what is known as deep mixing. Where contaminated soils characteristics and depths are suitable, deep mixing of soils with lime in combination with other binders can provide cost effective solutions for major contamination locations including lagoons and spoil heaps.