Solidification/stabilisation

Also known as immobilisation, this is chiefly used to change soil characteristics ex-situ (for handling or for a change of hazardous properties, to allow landfilling as stabilised waste), but also used by in-situ injection methods, akin to civil engineering methods like ground treatment or piling.

It describes the mixing of chemical or physical agents into the soil or water matrix, to solidify or ‘fix' the contaminants into an unreactive state. Chief additives include lime and cement, which reduce the permeability of the matrix, but there are also techniques using other minerals, such as zeolites or apatites, which change the chemistry significantly.