ASSERT - Kontroll av markstabilisering med resistivitetstomografi (ERT)

Soil stabilisation is becoming increasingly common for the development of areas with
poor bearing capacity. However, there is a need for better and volume-wide control
methods for quality assurance. The control methods can be divided into two steps,
where the first takes place in immediate connection to the mixing of binders to check
whether the entire intended volume has been successfully treated, or whether there
are zones that need completion. The second step focuses on the strength of the
stabilised volume and assumes that the binder has cured.

The R&D project ASSERT focuses on quality control using electrical resistivity
tomography (ERT). The idea is to use the method in immediate connection with the
mixing of binders to delineate the soil volume that has been treated with binders from
untreated parts. ERT could then be used to quickly check the results of the
stabilisation, so that supplementary measures can be taken in zones of insufficient
treatment while personnel and equipment are in place. Furthermore, there is potential
for volume-wide quantification of strength growth via correlation between change in
resistivity and change in strength during the curing process, but this would probably
need to be done on a site specific basis.

Testing and verification of the method takes place in different geomaterials in the
laboratory and in the field, including full-scale tests for different types of
stabilisations. Furthermore, method development and adaptation for the application
are included, so that the method becomes sufficiently robust and fast to be used
routinely in a sustainable manner. Field trials have been carried out by installing
electrodes in lime-cement columns and jet columns in direct connection to the
stabilisation. Laboratory tests have so far been carried out for lime-cement
stabilisation of clay and for stabilisation of dredged masses.