FRIPRO-Fri prosjektstøtte

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 (south of Mjøsa) are located below the marine limit. Consequently, 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. This interdisciplinary project goes through different scales, from fundamental chemistry at the nano-scale, to engineering and industrial scales assessing life cycle impacts. We have made significant improvements in understanding the behavior of quick clay at its fundamental scale through extensive numerical and experimental studies. This enhanced understanding is crucial for developing new ground stabilization technologies. At the meso-scale, we are currently testing various alternative materials and solutions. These tests are essential for identifying viable additives and methods to replace lime and cement in ground stabilization. Preliminary results from these tests are promising, indicating a strong potential to achieve a sustainable ground improvement technology by the end of the project. This development could significantly reduce the carbon footprint of infrastructure projects in quick clay regions in Norway. Additionally, we are working on making the entire ground stabilization activity carbon-neutral or even carbon-negative. This involves injecting and burying CO2 in the ground during stabilization, which could further mitigate the environmental impact of these projects. These advancements bring us closer to our goal of creating a sustainable and effective ground improvement technology, potentially revolutionizing infrastructure development in areas with soft soil.

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.