Soft and sensitive soils, such as quick clay, present challenging conditions for infrastructure development in many parts of the world. For instance, it is estimated that more than 80 percent of all cultivated land, settlements, and infrastructure in Trøndelag and Østlandet are located below the marine limit and potentially exposed to quick clay. This means, large infrastructure development projects in these areas require substantial ground stabilization. Due to its cost-effectiveness, ground improvement by deep-mixing using lime-cement is widely employed. However, considering the vast amounts of lime and cement used in these projects and the carbon intensity of their production, the contribution from these geotechnical works to the carbon footprint of large infrastructure projects in Norway (and globally) is extremely high, often being the largest single contributor.
This project aims to develop an alternative, effective, and sustainable ground improvement technology. It adopts an interdisciplinary approach spanning multiple scales: from fundamental chemistry at the nanoscale to engineering and industrial-scale assessments of life-cycle impacts. Through extensive numerical and experimental studies, we have significantly advanced the understanding of quick clay behavior at its fundamental scale. This improved understanding has been essential for developing the new ground stabilization technologies we are now pursuing.
At the meso-scale, we have developed and tested alternative binder systems using zeolite and lime, effectively eliminating cement from the stabilization process. Norway has abundant natural zeolite resources, making this approach particularly attractive and locally sustainable. Extensive laboratory scale testing has demonstrated that these new binders perform very well, confirming their applicability for soft clay stabilization. Additionally, we are working toward making the entire ground stabilization activity carbon-neutral or even carbon-negative by injecting and storing CO2 in the ground through stabilization process, which could further mitigate the environmental impact of these projects. Together, these advancements represent a major step toward achieving a sustainable and effective ground improvement technology, with the potential to significantly reduce, or even reverse, the carbon footprint of ground stabilization projects.
Soft soil, such as marine clay, gives challenging conditions for infrastructure development in many places in the world, which requires enormous amounts of ground stabilization. In Norway the major challenge is quick-clay (non-swelling illite). Due to the cost effectiveness, ground improvement with lime-cement stabilization using deep-mixing technology is widely used. However, considering the huge amount of lime and cement used in ground improvement projects and the carbon intensity of lime and cement production, the contribution from these geotechnical works, to the carbon inventory of large infrastructure projects in Norway (and in the world in general), is very high. Many times, it is the largest single contributor.
At the same time waste from concrete and bricks, and ashes are the largest contributors to the masses being deposited in Norway. These materials have a great potential as additives in the stabilizing technology.
We aim to radically change the deep-mixing technology by introducing sustainable alternative stabilizers based on solid wastes and creating a circular economy around this technology.
To achieve this goal, we need interdisciplinary research with a bottom-up combined experimental and modelling approach, across the scales and disciplines. At nano and sub-nano scale, we will employ a combination of numerical and experimental work starting with the water and ions interactions at illite-clay particle surfaces. At micro scale, we will combine thermodynamic modelling with experiments to investigate how the interactions between illite-clay and cementitious materials contribute to the microstructure and strength development. At macro scale, representative elements of stabilized clay will be tested and full-scale geotechnical problems simulated. Finally, we will calculate and compare the total environmental impacts of the alternative technologies.
