All you need to know about ex-situ stabilisation

Ex-situ refers to the treatment of soil when the soil is above the ground. The various technologies used in soil stabilization are applied to the soil when the soil is above the ground as opposed to underground (in which case it is referred to as in situ). One of the ways in which the soil is treated ex-situ is through stabilisation. This entails adding stabilisers to the contaminated soil, after which chemical reactions will be prompted between the stabilising agent and the contaminants. 

The chemical reactions aim to reduce the mobility of the contaminants (they make the contaminants stable). Some of the stabilising agents include; molten bitumen, emulsified asphalt, polyethylene and modified sulphur cement. Notably, ex-situ stabilization has its strengths and weaknesses. If you have a contaminated construction site and would like to have the contaminants dealt with, this article gives you all the information you need about the ex-situ stabilisation option.


  1. It is very cost-effective. Ex-situ stabilisation saves you a lot of money in transport costs, as well as expenses that you would have incurred when buying base material or aggregate. Before the stabilisation technology came into use, most contractors used to carry the contaminated soil or base material away from the site to a disposal area, after which the contractor would buy new base material for the construction site. This is unnecessary with ex-situ stabilisation. The costs of stabilisation are relatively cheap, with most experts charging about AU$8 per cubic foot for large areas and slightly more per cubic foot for small areas. Moreover, the reagents and equipment used in ex-situ stabilization are inexpensive and widely available.
  2. The stabilisation method can be applied to different types of soil, as well as on a variety of contaminants. This ensures that your options are hardly limited when you encounter new contaminants.
  3. It is time effective compared to other conventional methods such as extract and replace.


  1. The method does not remove the contaminants but merely puts a protective sheath over them. This means that your building structure will be seated on a mass of contaminants.
  2. The success of the procedure relies on the thorough mixing of the stabilising agents and the contaminants, which may be difficult to achieve.
  3. It is difficult to predict the long-term efficiency of the ex-situ stabilisation methods. Therefore, you will be required to invest in regular maintenance of the site to ensure the contaminants do not escape.